De TOMASO PANTERA GT-5. 9,4 Litre HEMI engine.

My sportscar.

I bought the car in 1990, hardley damage and rusty. I fabricated a new rear end, floor and doors.
From the start the car had BMW grafit grey colour. Later I painted it Golf pearl white.
........ Pictures of all the different engines that has been in the car over the years.
1990 feb. Original a 351 Cleveland motor. The car was legaly inspected for public traffic in 1991
1993 The car was on the big Stockholmsmässan in Älvsjö. Beside the car I showed my first build of the Hemi engine in its first version. A top fuel aluminium block and two dominator carbs. The set up was no success in the car, the block was smoking oil and the carbs didnt work very well. However, it looked impressive.
1995 A brand new 426 iron block. Half the money of a new aluminium block, but heavy, 116 kg. A strooker crank and aluminium rods made for 500 cui. An aluminium Mopar intake and a Holley 900 pro carb. This made a very nice driving set up.

1999 Time to install an EFI system. I machined the intake for 8 injectors and keept the throttle plate from the carb using an own fabricated throttle body on top of it. Haltech ECU, E6S. Good ECU but quite simple by todays standard. Best gasoline number was 1,35 L milen in 110 km/hr.

2000 The car had passed the inspection with the hemi last year, but not this year with the injection. So, an registration inspection was needed. It turned out great, and also the HEMI was added in the papers. The car is totaly legal.

2003 I refabricated the tunnel ram for the throttle body. Also, a new ECU, Haltech E6K. Good ECU, but wasted spark technology. Can handle low impedance injectors. 2004 New ECU, a Nira i3+. Better softwear than the Haltech.
2006. New ECU from Nira, model i7, fully sequential for both injectors and ignition. And the new Ev 14 Bosch motorsport injectors. 2007 This year I fabricated the 8 trottle system to be used on top of the old tunnel ram bottom. 2012 Time to uppgrade the engine, bought a brand new aluminiumblock from Indy and a stroker crank yielding 572 cui. Eagle rods 7,1" long and special fabricated piston for 14:1 cr ratio. For E 85 fuel.
2013 The head got 16 coil on plugs, from WV. Engine is solid mounted in the car by an aluminium plate that also braces the chassis. 2014 New ECU, from Maxx and a new trigger system using hall sensosrs and 30 earth magnet trigger wheel. Also, a new Crane mek roller cam. "245 dgr @0,50 makes for a little softer street motor. Top RPM 7000, which is enough considering a 4,5" stroke,

2016 The car needed a new paint after 26 years. White, not so hot inside during summer. Hemipanter ride video, you tube, click the pic.

Fabrikating new air filter intake system.

This scoop worked great, alltrought appear small it takes advantage of the airstream over the roof and keept the intake air temp almost the same as ambient while driving at speed.

On the 2019 pic the engine does not get cooled air, a little bad. But on the other hand it is a great packing and the power of the plenum makes up for that.

2019. Time for a new intake system. Still based on the tunnel ram but now using a big plenum chamber for a single trottle house.This is about the best set up by far, used on the engine. It got the top end of the two Dominators and the driveability of a modern car in city driving. Cold start handled by a separate air body seen under the air filter. And, it consumes 0.7 liter per Sv mile at 70 km/hr. 30% better torque than tha separate throttle set up in the mid range (2000-3000 rpm).

2020. I built another exhaust system. Here is the collector with its cone.

Headers and collector. The end pipes are in stainless steel.

................ .. ............... ............. . . My guitars.

.................I have been building guitars for 60 years. I have had customers from very early time, like Bill Healy.

My own bass model. The same shape and body size as the guitar combined with the Gibson length scale. The bridge is of solid brass. The picups is hidden and mounted from the back side. Each pikcup has its own channel and two amplifiers is to be used, preferably using an exponential horn for bass and some kind of midrange-tweeter speakers for the treble pikcup. The top is Rio Jakaranda.

The guitar is curly maple top. I use the same bridge of solid brass. The idea is to have good sustain.Fine tuning is made by filing the bridge for the type of strings to be used. Original cream PAF humbucker. These are very special sounding picups that hardley will be duplicated. One black and one cream. Picups that has to be listened to before speaking "copy" PAF sounds". It is specially the dynamic properties of the picup that is amazing.

The Abba guitar.There have been rumors about who made this guitar, as well as the exact design. Since ABBA museum and some coverband was interested in having the guitar in their show, I decided to produce two new specimens. However, I would thereby put an end to rumors about who made the guitar. Goran Malmberg.
ABBA with the star shaped guitar at the Eurovision song contest. Brighton.
Pick guard. Reconstruction of the guitar.
Some of my guitars are now showing at the Guitar Museum in Umeå. In addition, a mandolin in Les Paul design. At the top of an Explorer design but with corvetd top. Likewise, the Stratocaster at right has curved top in mausury birch. Me, Björn Ulveaus and Björn Clern, as well as the Abba Museum jubilee guitar.
................................Led Zepelin 1969 using my speaker cabinets.
    Photo from an early Cream video, Eric Clapton playing on my guitar. Special design head, in an attempt to put my own personality on the guitar. The body is hollow semi-acoustic.

......................................My music.

Here are some songs I recorded. Ghost rider and Apache are covers, the other songs are own compossitions. I use the bass as a melody instrument and have laid the backgrounds with a Kurzweil keyboard. Click the picture to listen and see the video.

Apache, med Speedlab Corvetten.

Klick the pic to see the movie and listen.

Skuggor, own composition.

Ghost Riders In The Sky. An old song.

Rain, own song song about rain..

Preikelåten, own song played on a cliff called Preikestolen, in Norway.

............................. ..... Weightlifting.

Powerlifting has interested me since the 70's. Sadly, I have to undergo surgey just over ten years ago that stopped me from lifting for 6 years. After that, I practiced a bit more quietly. At one point I read how the record in the bench press looked like and I thought that I might be able to beat. I started training more purposefully and the results began to come. I moved the training to my old club STK in Sundbyberg which is an established competition club with world names among lifters. There were some club competitions to start with and after a few years SM competitions. I beat the Swedish record in the bench and in a short period I also got a European record. To date, I have benchpress Swidisch Championship Gold, EM Silver in Tampere Finlandand, a World Chamion Gold titel in 2019 in Tokyo Japan.

Click the picture and yo see a video from my heaviest bench press at 180 kg. Not a perfect lift, but not a total failure. My first lift at the World Championship in Tokyo World champion in Tokyo 2019.

..................... How the hemipanter was built up.
The engine
Wheels and tires.
Building the engine.
Rollbars springs schocks
Weight savings.
Engine management.
A-arm geometry
Fuel injectors
Fuel injectors


The engine

Why a Hemi? It is a legendary engine. In fact, it is the world's most powerful and fastest engine there is. It holds the top fuel 1/4 mile record. The Hemi is like having some racing history in the car.

Heads. The heads is what separates a Hemi from other engines. It has been a lot discussion about Hemi vs the wedge design combustion chamber. As with everything, there are no optimum chamber design. It all depends on what we want the engine to do. Hemis have a 170 cc combustion chamber, great for top fuelers but not for a gasoline 426 engine, as we end up with 6,5:1 cr ratio with a flat top piston. Or, one must use a big dome that creates an orange-shell-shape combustion chamber with deep valve notches, shrouding the valves . But with the additional 100, or better still 200 inches, we can make the Hemi head shine. With a small circular quench-dome we have a street able 13,5:1 cr ratio, and a nice burning chamber.

Engine spec.

Engine is configured for alcohol use, E 85. Block is Indy aluminium Hemi . Crank 4,5 stroke billet . Rods 7,1 inch steel, ratio1,58:1. Piston 4,5 bore and 13,0:1 Cr. Heads aluminium, ported by KB. Aluminium rocker stands. Valve spring 200 pound seat pressure. Retainers titanium. Camshaft 264 degree@ ,050 roller. Intake, Rebuilt Weiand tunnel-ram manifold. Oil pump KB. Damper ATI . Oil pan, 11 quart wet sump. Exhaust headers 4 to1. Crank trigger hall sender and 30 tooth lost 2, wheel.

Building the engine

By 2013 I build an all new aluminium engine. This saves weight while at the same time offering the oportunity of having more cui for almost no extra money. 4,5 stroke and 4,5 diameter makes for 572 cui.

The engine plate also braces the rear of the car and put engine-gearbox weightover the coilovers.

A diagonal bracing was installed under the gearbox.


The shape of the pistons is important so I made a mold from plaster and send it to the piston manufacturer. The marking on the piston is wherw the sparkplugs are located This show what the HEMI combustion chamber should looks like.This chamber use dual plug and ofer short flame travel.
.The heads has steel rockers and aluminium stands. Eagle rods 7,1 inches long. Indy aluminium block converted to SBC water pump.

Gear shifter rod is supported by the engine mounting plate


The gear shifter handle is mounted in a straight line with the gear rod to promote easy gear shifting.

Front enginre stand. Tight fit for the gear rod.


Beside the drivers seat. Observe the distributor which now is only used for crank possition signal and oilpump drive.

New composite firewall door. Very light 4,4p flat with insulation and bolts.  
Hemi camwalk fix. On the inside of the cam cower there is a bearing thrust plate mounted. I am using zero end play.The layer consists of 3 parts, two outer steel shims and roller tray in the middle. I used a standard roller timing drive from Comp Cam:s, and machined all surfaces. An aluminium bearing centre was fabricated.
Injection system.



Weiand tunnelram bottom but without the plenum and I use two trottle body in its place.Stacks that is shaped to make a good air entry in to the runners and also making the runner a little longer, now 13,38". This is an aluminium tool for turning the butterfly to oval shape. Butterfly is sandwiched between the two aluminium clamping tool parts with two screws, using the two holes to be mounted to the trottle shaft.The diameter is 2,41". Injectors. 8 high impedance, enough for 1000 hp.

Engine management.

I use a Swedish system MAXX Ecu. I did all the injection programming on the road. I used a lambda sond for analysis. Equally important with ECU management is ignition timing, which could be set to any chosen degree over the engines entire rpm band. It even allows the engine to run cooler as the timing could be optimised to give crank energy instead of heat. The engine consume 15% less fuel compared to the carb. The lowest consumption at steady 60 mph, was 16 mpg. The season average is 14 mpg, compared to 12 on carbs. No city driving is represented in those numbers. The engine runs better in traffic, start ups and idles more reliably in coold weather. As for power output, the engine shows better performance over the entire prm spectrum .
The sensor for speedometer sits on the output shaft of the transmission. Then I will not have the 3-meter hastighetsmätarwiren that only malfunctioning and also do not show the correct speed. Electronic meters can be calibrated precisely. I use a simple hall sensors which only costs $ 4.


Oil pan. Is a story for itself in a wet design and this very low installation. This is my 4;Th pan. And now it seems to function properly. Of course, I could have used a dry system, as in my earlier Panteras, but the KB pump made a clean installation without to much hoses belts etc. And a stimulating challenges to make a wet pan to carry over 1g in any direction. A good design oil pan is important since it allows the use of smaller quantities of oil, without the risk of oil starvation. I want the engine to warm up quickly, which is not possible if too much oil is used. This pan is designed to hold 6 quart of oil, which is enough to prevent from any possibility to suck air. However, if I happen to be in a situation of a long distance driving, where there is a risk of the engine consuming oil, but it can handle an extra 2-quarter. The pan is safe in "normal" driving using 4 quart.

The oil pan sealing surface to the engine would most likely get uneven when welding. One way to get it straight is to tin putty and sand it . I am very pleased with this oiling system. A wet system allways has its limitations but with this in mind I could not expect it to be better. In any case, it is very much compact design.

The oilpan is a tight fit between the frame legs. It is flush with the underside of the car


Headers are 31 x 2,11 inches, giving the engine a peak at 5500 rpm. I have my own (guitar tuning) trick of tuning the exhaust primary pipes. By listening to the note of the pipe, it is possible to tune all primary (and secondary pipes respectively) to the same frequency even though this might result , due to bends and such , in some discrepancy in actual physical length. Think of it as an organ pipe. Sing a note in the pipe listening for the resonance to tune in. The frequency is a function of air volume and pipe length. Staggered pipes they may be , but we´ve got the resonance length spot on!. And frequencies is what the engine senses. A fraction of an inch is easily detected in the variance of note. End pipes are 3 inches x 25. To quiet the car I use a large silencer, pictured later in this site.

Another interesting side effect of "guitartuning" the exhaust is that it provides great music! Especially with the very short system of the Pantera which responds to almost any change in pipe design. And as no surprise, good note and performance are more often than not very , closely related.

180 degree headers, 90-degree headers, tri-Y headers. Well, I use regular headers. In my earlier car I have been using all type of headers. The 180 and even more so the 90 headers give a V-8 the same sound as a 180-degree crankshaft or V-12. They also look impressive. They do have some tuning advantage and a few more horsepower. But, this design almost allways comes out with too long primarys. Making them suitable for lower rpm engines. On the other hand, regular headers will be to short in the aviable Pantera header-space. With the wide Hemi motor 180;s are an almost impossible fit in the Pantera. The Hemi has a special sound to begin with, that are greatley backed up by regular design headers. After a lot pipe tuning I am proud to say that the car has received a lot attention for having a great heavy sound.

My 302 Boss Trans Am engines built by Falconer Dunn. Fords highest reving engine ever. 9000 rpm in the Ford catalog. Here equipped with 180 degree headers. The end pipes is close together, important for a great sound. This particular engine produced 427 hp. Four IDA Webers and dry sump oiling. 90 degree headers on a 500 Ford big block. I used this motor in the late1980;s. This system was very quite, and nice sounding. The silencer had a 4 inch core diameter My first big block Ford motor for the Pantera, 1985. This is a 385 series 460 stroked to 500 cui. Using Ford motorsport aluminium headds and intake for dominator carb. Dry sump system and electrical water pump. Also, 90 degree header system.

Fuel injectors

Top, "bosch 040" 940 cc injector has good atomization. If we want soething really nice! This is the Volvo Bosch 214cc injector. Here at 66 psi fuel pressure. Lower, compared to RC injector of compareable zice 880 cc, sort of shower style beam, not to great. RC inj266 cc injector of similar small size, Not to bad but still not as good as the much larger Bosch 040.
Injector test bench. To b e sure the injectors are up to spec I made my own test bench Bosch Ev 14 injector i delar. 2000cc.


It is important to have a both quite and efficent exhaust sytem.The main silencer is a perforated tube. Inside baffle is showing inside. The outside of the silencer is cowerd with fibre glass. And finally the aluminium cower is in place.Tightened in place by two large hose clammers 2 end pipes each side as the original look.The end pipes are slided over the final muffler tubing.


Theories. The Pantera is a neither a ground-nor wing-effect car. Well, the GT-5 does sport a big cosmetic rear wing. Over the rear hood.... probably creating "wing to hood" down force instead of "wing to ground" down force. What is important is how the dynamic weight distribution affects the car. This depends on the whole car as a concept. Extra friction is created by the use of a large and soft rubber area. And it is desirable to under all driving conditions keeping the weight distribution as even as possible over this rubber area, (except during acceleration). Under braking and while cornering all four wheels are used. This calls for a low centre of gravity, in order to to minimize weight transfer. Under acceleration only two wheels are used to move the car. Now the entire weight needs to be at the rear wheels. What is good in one situation is easily disastrous in another. So, I work with what I percieve to be a reasonable static centre of gravity . Which in the case of the Pantera (when over 500 hp) is 60-65% rear bias, backed up by the same proportion tire area. This gives me 55% front load under 1g of braking and thereby a good help from the rear tires. At 1g of acceleration I got 70% rear tire load, to secure a good grip. Then using sway bars, springs, shocks and suspension geometry to handle the weight transfer in the best possible way under different driving condition.

Chassis stiffening. My idea has been to reinforce the chassis in a monocoqueish manner . As said, the whole chassis support torsional stability. Certain areas support more load than others. These areas are "profiled" by the same 0,036" sheet metal. Often with a diagonal middle wall, in a three wall "tube" like profile. To make a supporting profile made from 0,036" steel strong, one must see to that the metal recieve straight loads. In other words, there should be no waves in the sheet metal when welded in place. Something which takes an experienced chassis tecnichan to do . The Gt-5 skirt. (rocker panel) was originally made in fibreglass, thus only creating a good looks. I made them in steel, integrated in the chassis with a large cross sectional area. These type of actions stiffen the chassis with neglible addition in weight , which is the very idea with a monocoque. I do have a roll cage, but this is strictly for driver protection. However, I have been driving this car for 16 years with racing rubber. And 8 years with the Hemi. And , to date , without any type of flex related problems.

Chassis frame structure.

This is a wooden chassis model of the Pantera "frame" structure. I made this to sort out what happens to the chassis under stress. The model is then dressed up with an outer shell, simulating the outer body panels. The model is twisted, and stressed in all kinds of ways. As a structure only and with outer panels, roof and floor in place. Different types of bracing are applied to see where it does some good. There are two areas of concern, 1. The rear section, 2. The coupe. Needless to say, the structure alone is no stronger than a playing card

I have been driving th Pantera with different torsional stifness numbers and with stock setup coilovers there is hard to separate 5000 to 15000 fp/dgr from each other.

But with racing tires and 3 Hz springs and matching dampers, tuning becomes more exact. What really loads the the chassis is the dampers, so schock settings is what is the moost noticeable.

Chassis bracing

Two electrical plastic tubes is used for measuring tool. Inside the two sliding pipes is a spring that keeps the expanding tool in place.All measurments is performed at a torsional load of 3000 foot pound.It is importanr to understand that in order to stiffen the car we MUST recognice areas of movement. If there is no movements, there is no gain by placing a bar in..

Diagonal engine bay lower part.+0,04 ", 1mm. Diagonal engine bay. -0,125", 3,2mm. -0,14", 3,7mm. +0,011", 0,3mm +0,0197", 0,5mm. To frame. Engine bay horisontal. 0,00 " Rocker panel to roof-window pillar. -0,01" 0,25mm Coupe diagonal. 0,018", 0,46mm. Right door+0,02" 0,5mm Left door -0,02", 0,5mm

Hemipanter has a torsional stiffness of 15500 fp/degree.

As for references. Lamborghini Countach 1900 fp/degree. Ferrari 360 spider 6250 fp/degree. Viper gts has a "tube space frame" and 9000 fp/degree. Viper gts-R (Le Mans 24 hr) is reinforced to 13600 fp/degree. Lamborghini Murcielago also uses a high strength tube frame supported with honeycomb carbon fibre to 15000 fp/degree. It clearly shows that the Ferrari has no roof. Here we have cars with cromolly tube frames, carbon fibre, etc. Exotic material, loudly advertised as great stuff that makes those sport scars outstanding. Let me mention that the new SAAB 9-3 Sport Sedan, steel monocoque has a torsional stability of 16000 fp/degree. Showing that good engineering is more important than the use of fancy materials. Embarrassing for the SUPER cars? The Panoz racing car tub carbonfibre monocoque has a stiffness of 45000 fp /degree.



A car wing works in the same manner as an aircraft wing, but upside down. The lifting "vacuum side" of the wing is now the underside. The wing works the best when close to the road and in an undisturbed air stream. Like the front wing of a formula 1 car, that create a high vacuum against the road. The Pantera rear wing is mounted over the rear hood. Creating vacuum between wing and the rear hood is of no use. It is like lifting oneself in the hair.

For a rear wing the only free air stream is quite high . It should also be mounted way back. Wing-(s) should also be positioned so that the centre of down force is located aft of the centre of weight gravity. This self stablices the car at high speed in the same manner as an arrow with feathers in the rear..

The original location of the rear wing. If one want it for looks only, this is OK. It stays within the size of the car itself. Check the wing location of a Trans am car! New test location of the rear wing. In fact, now it begins to make some good. The angle of attack is a shot in the dark, and gives 150 pounds of downforce at 94 mph. Adding 8,5% tracktion at the rear wheels. From here I will go on testing. This is the cooling air outlet director. A single powerful fan from Audi fabricated by Siemens, is used. .Fabricating a new front hood in fibreglass.Sandwished with bonocell layer.

Coupe, seats, dashboard, bumpers.

. Balsa wood bumpers! Since lighting is needed, I produced a "LED lamp" panel that provides 50 lumens.All external surfaces are covered with gauze from care, glued with wood glue. A thin layer of light trowel smooths the fabric pattern, but only on the outside. It weighs 215 grams, complete with bolts and everything.


More horsepower in the car it is often said that one must follow up with more brakes. I agree, but with a few corrections. Street speed depend more on the driver (if he like to keep the licence or not), than on engine output. If a 3000-pound car is to be stopped from 100 mph, we need brakes for that purpose. Not for how fast the car can reach 100 mph. On the racetrack more HP always result in a rise of the average speed, as the car always is used to its limit. Race car drivers knows exactly where to go off the throttle and start braking. This is not the case on the street. Road, sports car drivers must use a safety margin. This margin makes for more cooling time. So, I will not use bigger discs than just what is needed to prevent from overheating. Unnecessary disc weight reduces cornering power on rough surface road.

I will use the very best low temperature working pads. And no bigger or heavier calliper-pads than needed for even pad wear. The master cylinder system should be balanced for the callipers used. Of course, one can make a few laps at the track. And some very fast laps to, before it is time to stop and cool the discs down.

. With this in mind I designed the brake components to make a light combination. Therefore, although weaker than iron, aluminium callipers is used. Aluminium has a flex module of 10 and steel 30 million. I use one piece and closed back type calipers. I fabricated this one-piece aluminium hub (image) to mount wheels, discs and front wheel bearings. Discs are Lockheed, 20 mm ventilated. Until now I had no experience of overheating (on public roads). It may also be possible to use solid discs (only for the streets) as they offer slightley better stopping performance because of better clamping support, and are less prone to cracking. Great feature for one big high speed stop to zero. An often overlooked factor is to use the right type pads. The right pads makes the original Pantera Girling calipers more than enough for any street Pantera. The only problem is that they are heavy. Two important brake factors is, ALWAYS a yearly change of brake fluid and the right pads.

ISR brakes.


This 4x1,3/4" piston calliper, weights in at 4,84 pound! The calliper uses 4 pads for even disc pressure.These callipers was used by the NASCAR teams until they where out ruled. Only 2 pads are allowed. We will see if they are up to my demands.......

Calliper piston.

Master cylinders for the clutch to the left, and the two balance bar working front and rear brake cylinders. Suits fine on Pantera original aluminium mounting plate.

Powerfull braking, measured in G-force, is a complicated story, greatly depending on how the tires is loaded under during retard. The reason racing cars use huge brakes are to withstand repeated braking. In a way that newer occur on the streets. Big size calipers and fat discs does not produce higher braking G;s. No matter how big, red-painted and racy look the brake system is, it is impossible to create more stopping force than the available tire friction against the road. Pad area does NOT affect braking torque. Big discs and calipers does NOT create tire friction. Heavy braking force is a question of downforce, car balance, tires and a matching brake balance. So, very much attention has been paid to this matter, and, by making use of all four wheels and not only the front wheels, to stop the car. As known, the biggest rubber area is on the rear wheels of the car, and accordingly, in my case, they should carry 1560 and the front tires 1040 pounds during 1 G of braking for optimum braking power. But in reality the car produce a weight distribution that gives 1144 rear and 1456 pounds at the front axle, or 56% of the weight at the front wheels at 1-G. Briefly, this will lower the tire-Cf and thereby reducing braking capacity by 5-10%.

A Porsche GT-1 will brake around 1,05 G over 100-0 km/hr. However, from 200-100 km/hr I am heavely beaten by the GT-1 as this car has better aerodynamics.

Physics of braking

Wheels and tires.

Wheels are original GT-5 Campagnolo 13x15 and 10x15. The Campagnolo and racing tires makes a very light combination, and wheel weight is of vital importance for a sports car. One rear wheel is 39 pound. The wheels is a unsprung weight that must be controlled by the shocks. A rotating mass, that must be accelerated in both rpm and distance. A lot myths is circulating around tire dynamics. But her we are looking at real physical life testings.

As we know, the coefficient of friction is altering with area load. The less the load the better the coefficient, therfore larger tires gives better grip. However, if we try to calculate the balance of the car by using input numbers of the tire size, we are getting a spot of troubble. One misconception is that the tire contact with the road would be met by air pressure in the tire. Simply put, it means that if the air pressure is 2kgcm2 and the burden that rests on the wheel is 400kg so is the contact area 200cm2. As we will see here so this is not the case.


This is the Pirelli footprint. At 880p and 29 psi it gives an area of 147cm2 compared to 340 for the racing tire. Raising the inflation to 42psi did hardly show any difference in area size. This show two things...

1, the tread pattern is geatly reducing the area.

2, the construction of a street tire is much stiffer than that of a racing tire.

The two tires are Avon racing slicks, compared to street Pirelli P-Zero there is a huge different in footprint size for the same size tires.Both those tires has the same diameter and a tire pressure of 25 psi. As can be seen, the wider tire show a shorter but wider print. The 10 inch tire has a print area of 308 cm2 and the wider tire 340 cm2. At a load of 880 pound



The image to the left show tire contact area in kg per square cm. At a tire inflation pressure of 2kg/cm2, or 29psi and 500 kg (227p) of load, we got 1,9 kg per cm2 of area. If we lower the inflation to 1 kg/cm2, (14,5pis), the load per cm2 will be reduced to 1,42 kg/cm2. If we divided 500kg by 1,90kg/cm2 we get 263cm^2 printarea. When lower the pressure from 2 to1kg cm2, we got 500/1,42=352cm^2 print area. So, half the iflation pressure gives 34% larger contact patch, not twice that much. A note, the tire does not carry the same load over the contact area, and the contact area is not in direct proportion to inflation pressure. A big amount of the advantage of wider tires is that they should be used with lower pressure on the same car.

Rollbars springs shocks and A-arms.

Rear suspension.

My (own fabrication) uprights.This is a "BOX" casting. With no open sides. This makes a tremendous difference in twisting stiffness. This one weights 8,8 pounds. Original steel is 13.75 pounds. Construction sketch. The shaded area is the stainless bearing holder. (Pictured above with the outer bearing mounted. The bearing play is set by shims between the axle yok tightened by the axle nut.

There are two sealing boxes outside each bearing, running directly against the inner bearing race. Even the inner bearing must have a turned seat in the upright. What cannot be seen on the drawing is that the inner bearing has a 1/4" smaller outside diameter, but is slightly wider.

The rear A-arm with dual coilover mount. Alter the wheelrate from 120 N/mm to 76N/mm.The slightly changed geometry of the rear suspension in order to be able to use the different coilover settings. There where no problem whatsoever to take the entire suspension apart after two years of duty. No problem with the conical bearing in the uppright. When making toe or camber adjustment, just unbolt the front leg of the A-arm. When alignent is fixed, adjust the length to suit the new angle. No bindings then.

Front suspension.

Front A-arm system, longer arms, more parallell and thereby less camber compensative. Spindle parts. Lover balljoint is Saab. 1 dgr spindle angle. Caster is schimmed to spec. The front uppright. Upper spindle joint bearing and bolt.

 Weight transfer

The front sway bar of the Pantera has a spring lever ratio of 0,16. This means that the bar spring rate are to be multiplied by 0,16 A bar with a spring rate of 650 pund/inch, times 0,16 is 104 pound/inch at the wheel. The equation is, bar attaching point length = 135mm A-arm length = 335mm equals 0,40. 0,40x0,40 = 0,16. Rear motion ratio is 0,70. The same is true for the springs. Motion ratio is 0,71 front and 0,75 rear. Just multiple those numbers with spring rate and you got the wheel rate. To calculate motion ratio for the springs, the angle of the coil over must be taken in to consideration. However, this numbers does not apply to my new A-arms.

Spring wheel rate. Are 386 pound/inch front and 585 pound/inch rear. I am talking wheel rate, as this is the rate the car uses against the road. Wheel rate is less than spring rate because the lever of the A-arm. Divided by the car weight we get spring frequencies, a number that show how hard the car is sprung. This numbers are 3hz front and 2,8 hz rear. Together with the roll bar this balances the weight distribution off 62 % rear and 38 % front to almost neutral steering. Equally important are where the masses is located on the car. And they should be located low down and in the centre of the car. Ideal for the Pantera since it has no ground effect. If there is anything I really miss on the car, it should be a better design under body. My first Pantera was even heavier in the rear, 66%, and accordingly show better braking numbers, but more sensitive to tune in corners. Shocks are Öhlins.

A-arm geometry.

Pantera A-arm geometry is not much to be proud of today, creating a miserable change in spring-wheelrate and a few other undesirable effects. F-1 cars use long and very much parallell A-arms. That way we got insensitivity to camber vs ride height variation due to aerodynamic force without affecting camber compensation too much. The F-1 theory does not apply very well to this sort of sportscar, but some of the thinking is usefull. What I am trying to do here is to keep rollcentre height at the same level and GRc lateral movement under control in order to keep weight transfer and its distribution, geometric-elastic front to rear the same during roll.

Top, original Pantera front suspension geometry.

With the low ground setting there is quite a steep upper A-arm angle. Also the lower arm has lower pivot centre in the chassis. Not the very best, allthrougt giving acceptable roll centre height. One other problem is the SAI projection point that hit the ground at 1290 mm distance, creating a big scrub radious.

Top, original Pantera rear geometry.

Very short instant centre gives a "swingam" like wheel travel. Together with a large scrub radious, wheelrate is getting lower. I made up a formula, for use in an excel sheet, showing what happens. =(SIN(C2*3,14/180)*(B2*F2)/(A2*(F2+E2)))^2

The new A-arm geometry, front. Rc at 11,2 mm. New rear geometry. Rc at 30 mm.
This is the FRONT suspension. The geometry used is such that the roll centre height is keept within 0,2 mm during 1,5 degree of roll. Also, the jacking forces are almost neutralized over the left and rear sides, so very little lifting movements are present. This means that the rollarm remains pretty much constant over the roll-movement. 1,5 dgr of roll means 0,8" of deflection, or 20 mm. With that in mind I set the rollstiffness so that I got 20 mm of deflection at 1,3 g of cornering load. As the CGH is 415 mm or 16,3", I got 415-11,3=403,7mm rollarm. Sprung weight is 1000 kg. 1000*1,3g =1300kg. 1300*0,4037= 525kpm of Mot.

This means a rollstiffness of 404 kpm per degree. Total Wt = 415mm* 1,3g *1220Kg/1560mm=422kg. The outside pair of wheel is then carrying 1032 kg which means 85% of the side load.

As seen in the drawing to the right where the car is under roll, the geometric Rc has moved 73% of the Tw to the unloaded wheel side. Idealy it should have been 85% according to the Wt number. However, the forcelines are low so the height difference at the side of GRc is low, which show the advantage of low forcelines. To cure the problem I could lower the Cgh to 300 mm, which is not easy. Another solution is using more parallell A-arms but then the cambercompensation situation is getting vorse. Low forcelines and long A-arms does also gives the benefit of less lateral scrub during heave, good braking nd acceleration grip from less vertical movement-camber change, or if aerodynamic downforce is present. Low Cgh is mandatory from all points of view.

The rear suspension is not showed, but A-arms are shorter and thereby victims for a larger compromice. GRc is only moving 195 mm resulting in a larger jacking force. I tryed to keep the cambersituation as equal to front as possible and the outside front is -1,28 compared to the rears -1,4 degree @ 1,5 dgr roll.

This is a model used to check out body-roll depending on Rollaxis angle. I has been a lot written and talked about this phenomenon, but I dont know if things are sorted out. Computer program is great, but to me a physical model is very dependable, and this model is able to handle both right and left tire grip load, which is very important since load affect jacking forces.

As the model is set up here, we are having a very high Rc in one end of the car and an almost ground level Rc at the opposit end. In this case the model show that weight distribution front toreae has an influence on the precentage of geometric antiroll of the car. However, this setup is not really used on any car, but it show the principals we have to deal with. Using longer and more parallell to ground A-arms at all four corners will take the hazzle out of the calculations and make it much easier to deal with.

Even if the term Rc appear a bit dizzy, in reality it is not. With a properley designed A-arm system Rc can be pretty much fixed at the centre of the car even as the GRc is moving sideways. Rc is useful for establishing the rollaxis.

New Pantera design.

Recently there was a new design, or should I say new dressing, for the Pantera made by someone thinking it needs a new look. Ok, from my point of view, the look should remain pretty much the same as before, although 2 meters wide 1 meter height and 4,1 meters long and some modified fenders for larger wheels, as fare as design is concerned. Then the similarity will end, a totally redesigned chassis. Front track 1670 mm, rear track 1645mm, wheelbase 2500mm. Ground setting 70mm. Rch 15mm, Cgh 300-350mm, weight 950kg, zero antidive and squat, Front and rear SAI 1 dgr, scrub front 15mm and rear 20mm, 30% Ackermann. Brakes are 12" discs x 1,25. Hight mounted rack and pinion which takes another A-arm layout. This will do away with roll and bumpsteer troubble, and at the same time get rid of any 3:e A-arm leg influence from a steering rod monted in between tha A-arms. Pushrod suspension. Front and rear frame lower tubes together with the A-arms is using a higher location in order to house an aerodynamically efficent bellypan and diffusors. Totally new design spindles and upprights located in a way that reduces internal loads and also on both steering rods and rear toe leg rod. Pushrod angle and location is such that A-arm load is greatley reduced. Rc is adjustable by horizontally mounted inner A-arm bushings and spherical bearings is used in moost cases as they permit better forceline centre in the A-arm legs. But even a few heimjoint is used for adjustability but mounted in such way that they recieve straight loads. I was figuring the car should be right hand drive as European tracks are mostley running clockwise.

The floor is marked green, and the feets will be higher becouse of the raised front structure. A-arm attachment are blue, rack&P is yellow and wheelcentre red, just so we can compare to the original Pantera locations.

The scale of the drawing is pretty exact, but is only showing the main tubing for simplicity. Triangulation is very much left out.

Photoshop image to visualize what the Pantera may look like modified according to the drawings. I didnt put to much effort using Photoshop, just eough to get an acceptable image. Front air dam is moved forward for better splitter function. Wheel house openings are rounded and moved up. Wheels are 18". Car is 1000mm in height. And the diffuser together with radiator air exit out the side. Rear diffusor added.

The intention is not to create a better looking Pantera but to house a racing chassis in a body still looking as much as an original Pantera as possible.

Corvette C6 and Viper suspension.

As for comparsion I made a scetch of the Corvette and Viper suspension system. One might wonder what the engineer come up with for those cars as they provide a fairly good ride while still maintaining braking, cornering and acceleration performance that good. There is a lot to be said for a comment to these drawings so I want go in to details, but so much can be said that those cars are quite soft in heave and to cope with horizontal forces they have a good deal of anti:s in all directions. The Corvette is on top and Viper below. To the left we have the front and to the right the rear suspension. Middle part is the cars seen from the side where the CGH line is common for both cars for an easy comparsion and the wheels on the sides is seen from the rear or front.

I was figuring of making a Ohlins coilover setup for these cars if time so permit. The idea is to create a sporty set up more suitable for road racing.

A-arm geomerty


Length 167,32 Tire R 13x25x15 Rollbar front non Mr F rollbar 0,27
Width 78,66" Spring stiffness front 3,11Hz Rollbar rear non Mr R rollbar 0,54
Height 41,53" Spring stiffness rear 2,81Hz Roll distribution front 43% F-axle load at 1,0 G braking 1487 p
Frot track 60,60 Wheel rate total   Roll distribution rear 57% R-axle load at 1,0 G braking

1252 p

Rear track 63" Deflection at 1-G cornering 0,57" Roll centre front 0,45" F-axle load at 0,88-G accel 630 p
Wheelbase 98,42" Deflection in degree at 1-G 1,08dgr Roll centre rear


R-axle load at 0,88-G accel 1950p
Weight 2525 p 1148kg Roll stiffness kpm/degree 330 kpm Spring rate F 735p/" Camber gain @ 3/4" bump  

948 p 431kg

Overturning moment (Mot) 357 kpm Spring rate R 1200 p/" Camber gain @ 3/4" rebound  
W-rear 1577 p 717kg Suspension drop front 1,1/2 inch Wheel rate F 386p/"

Camber gain @ +5 dgr turn

Wheel F 10x15 Suspension bump front 1,1/2 inch Wheel rate R 505p/" Camber gain @ - 5 dgr turn  
Wheel R 13x15 Suspension drop rear 1,1/2inch Mr (motion ratio) F coilover 0,525 Unsprung weight inkl wheel F  
Tire F 9,1x23,5x15 Suspension bump rear 1,1/2 inch Mr R coilover 0,423 Unsprung weight inkl wheel R 86,9 p

Wheel loads at different actions. Original Pantera estimates for comparsion.

Hemipanter   Hemipanter   Original Pantera Original Pantera
Left F 255p Right F 790 p
Left R 427 p Right R 1267 p
173 p 710 p
506 p 1346 p
231 p 1034 p
383p 1454p
Original Pantera Hemipanter
F-0,75 G acc 856p = 27% 23 %
R-0,75G acc 2246 p = 73% 77 %

F-1G brake 1810 p = 58%

52 %
R-1G brake1291 p = 42% 48 %

Transfered weight 685p

Wheel load at 1-G of steady state left turn cornering.

  Wheel load at 1-G of left turn cornering. with a combination of 0,37 G acceleration..  

Transfered weight 935p

Wheel load at 1-G of steady state left turn cornering.

These numbers are for the same G numbers to make a fair comparsion. Due to lower CGH the Hemipanter should have showed less than 77% rear weight at acc, but static rear weight is higher.

Wheel alignment.

SAI 1 gdr Scrubb radius 106 mm Toe (out) 0 Ackermann 30%
Caster 3 gdr Camber - 2 gdr Rear toe in 2x1,0mm Bump steer 1" rebound +-0,2 mm

Weight and weight savings.

Weight. 2350 pounds. How is this possible?. Drill holes in every bolts, plastic windows, fibreglass hoods, small battery, no frogeyes, etc, etc. Even so, I is trying to give the car at least some kind of comfort. Like some heating system when chilly and electric wipers.


Me, standing, and the Speedlab guys loking at drawings.

Planned design of the car.

Breif design of the front wheel centre line cut seen from the rear. Engine is offset to the right. 18 inch wheels 13 and 13,5 inches wide, 650 front and 710mm rear diameter tires from Michelin. Total height 40 inches = 1000 mm..
This is the twisting test of the chassis. The front bar is anchored to the floor at the outer end and is resting on a floating stand in the middle, all to elminate bindings. The "starting out" twisting showed a mear 4000 fp/dgr, where the largest nuber was read in the engine section of the chassis, and the roof as a good number two. After crossbracing the roof and mounting of the engine the number went up to 8000Nm/dgr. Bar is 2 meters long for an easy Nm reading. The centre of the rear is also ancored to the floor, hanging in a wire. The chassis is lifted up from its "resting" location during the test.
By using telescopic tubes I detected the largest flex to occure in the front window area, 1/8", so an diagonal tube was welded in place as seen on this image. Now the redaing get 18000 Nm/dgr. We still got a 1/16" flex in the engine section, and the coupe floor that is describing "waves" under loads. I am looking for (hopefully) some 30000 Nm/dgr as a final result.
Observe, I banned the use of any bent tubes in the new part of the chassis. The Old trans-am part (red) is and was full of them, which made it no (better) stronger than a wet dischcloth..
Engine mount plate.   HM damper and oil pump drive. I made a new hub with a longer "neck" to be able to mount the belt-drive on the inside of the damper.Oil evacuation permits very short hoses to the pump. Rear mounted starter motor
2016. It has been a few years since the car was constructed, and it is time to update it in a number of areas. Both in terms of things that have not worked to satisfaction, as well as more modern designs developed. We also decided to run the "Time Attack" racing because the car is difficult to classify into the competitions running in Sweden. So far, time attack is a relatively free class in terms of modifications that are allowed. So we built a new front, new splitter with diffuser and two turbochargers and sequential fuel injection and ignition.
Turbo installation    
.Mantorp. 2010. 2017


A chassis engineering book that show the build up of the Speedlab Corvette race car.

This is a book about how to build a racing car. I describe the process step by step, using the build up of a racing Corvette as a working example. For those who like Corvettes this might be of special interest. I am using a building theory of my own called the "Zerocar" philosophy. The Zerocar is a car that has practically no suspension angle's, ground level roll centre and no anti's. What makes a racing car faster than a production car around the track is that it is optimized to do what it is set to do. A daily transporter must be able to do a number of things and be able to drive in sun, rain and snow. The race car will become a nightmare in snow. This means that the daily driver is having a number of features that has no place on a race car, and will therefore not be very good to use as a platform when explaining the building process. The Zerocar is a "clean" car where we only need to add what is needed to make it suit our application, no less, no more.

The book include...

Aerodynamics, tires and wheels, braking systems, dry sump systems and effective oilpan design, cooling systems, exhaust systems. Calculations, math, tires, wheel alignment, suspension geometry, springs, swaybars, a quite large section about shock absorbers, engine management systems and injectors-sensors. Everything very much down to earth, to make it possible for a small team to build a fast car.

The book is in English. A4 format, 315 sides and 457 images.

Sold by https://speedlabacademy.se/

Väghållningsboken. Behandlar väghållning i allmänhet. A-armssystem o fjädringsberä kningar, däck och stötdämpare. Beräkningar för bromssystem och grundläggande broms-fysik är ingredienser i boken. Även lite aerodynamik och hur under-sidan av bilen med splitter samt en vinge fungerar, men även lite motor-teknik som kylsystem, avgas o insug-ningssystem och torrsusumpsmörjning finns med. Bra bok för den som redan har en färdig bil och vill jobba med instälnningar o service. https://speedlabacademy.se/






Goran Malmberg.