Larry Holt On The Panoz Esperante GTLM

On the eve of Petit Le Mans at Road Atlanta – the scene of the Esperante’s first ALMS win in April – Alan Lis forwards this Q & A with Multimatic’s Engineering Services Group vice president Larry Holt, on the subject of how the two companies worked together to produce a racecar capable of taking the fight to the Porsches in the ACO’s GT2 class.

The works Panoz Motor Sport team was back at Le Mans in 2005 after a one year gap and arrived on the crest of a wave, having inflicted that rare defeat on the factory supported Porsche GT2 teams. The Panoz Esperante GTLM is based on a road car design that first went into production in 2000. The production car and the 2005 racing GTLM are the result of a close technical partnership between Elan Motorsport Technology, the Road Atlanta based competition arm of Panoz Auto Development, and the Toronto, Canada, based engineering company Multimatic Inc.

How are the responsibilities on the Esperante ALMS programme divided between Multimatic and EMT?

“Multimatic builds the chassis. Elan Motor Sport Technology’s chief engineer on the job is Christian Rushforth and they sub contracted the chassis development to us. There is also a tie-in with Esperante road cars because we design and build everything from the rear bulkhead back for the production car.

“That’s part of the racing background of Multimatic: we are good at working in steel and other metals. EMT is very much a composites material oriented company making Panoz IRL cars and stuff like that. We have got a lot of experience with touring cars and showroom stock type cars, they so they gave us the development job for the chassis. Pretty much everything in terms of chassis structure comes from Multimatic.

“For the build of the racecars, road car chassis are shipped from Atlanta up to our factory in Toronto. We build up the chassis and ship them back to EMT, and they build the rest. We split the bodywork up, the bodywork design is 100 percent EMT, but we tooled and built most of the big bits like the hood, the deck, the quarter panels and the fenders, and they are made in Toronto.”

How is the Esperante chassis assembled?

“The cars are built around a peripheral frame made of aluminium extrusions bonded and riveted to a central steel structure, and it’s connected using a patented jointing technique.

“It makes for a chassis that is extremely stiff and easy to manufacture. It means that we have really strong corner joints in what is around the outside of this car, and carries the front and rear sub-frames. In the middle of the frame is a stamped metal part we call the FBA firewall floor assembly, that is actually based around production Ford Mustang pieces. When the crash testing work was done for the road car, PAD was able to extrapolate a fair bit of the original Ford work.”

“Multimatic’s expertise in aluminium structures includes producing the aluminium chassis for the Lola B2K/40 SR2 sportscar and working on the first prototype of the new generation Ford GT and the stillborn Aston Martin GT1 supercar project, but the Esperante chassis design is entirely Danny Panoz’s deal, he is an excellent all round engineer and he engineered the original car.

“The current racecar is kind of a hybrid structure, but saying that, we have now gone to a second generation road car chassis, which eliminates all the steel bits in the middle because those parts have gone out of production with old style Mustang.

“In the Gen 2 version, the centre section of the chassis is a single, large, carbon fibre piece. With extruded aluminium construction around it, it is lighter and stiffer. The new version of road car is being built like that and in the future the racecars will go over to that design. In 2005 the centre of the racecar is the production car, with a safety cage built into it significantly stiffening the car, and the front sub-frame is tied in a little tighter.

“Chassis stiffness on the racecar is up about 15-18x compared to the road car, but when we put the carbon floor into the road car that increased the stiffness by 3x. Stiffness has also improved on the road and racecars as the rear end design has evolved over the years from the original road car. Four or five years ago it had a Cobra Mustang rear sub-frame, coupled into a bespoke chassis with pushrod inboard suspension. Ultimately that got done away with now it’s a single chassis and no Cobra sub-frame, which makes it much stiffer.

“Jay O’Connell, who is ex-Jaguar F1 and Ford Racing Technology, sorted out the geometry on the road car. Jay worked at Multimatic for two years, until Christmas 2004, when he went back to Ford to work as the chief engineer at Special Vehicle Engineering. The rear suspension on the car now is a Jay O’Connell design that he came up with when he did the FR500 at FRT and we use that, with Dan Davis’s, the head of Ford Motorsport, blessing on the Esperante GTLM. It’s a very good design.”

In 2004 the Esperante racecar never quite realised its potential. Was there a particular reason for that?

“A major performance-limiting factor in 2004 was that it got incredibly hot inside the car. There’s a big engine at the front, the exhaust pipes run down the sides of the car and the firewall is a steel panel, which readily transmits heat. There’s not a lot of heat extraction from the engine bay, because when you put on the underfloor that you need for the aerodynamics, you seal up that area. Front-engined cars just get stinking hot and there’s not a lot you can do about it with conventional methods. You can’t open the side windows because that will affect the aerodynamics. Our drivers use a helmet air conditioning system with a heat exchanger. That turned things around for us because things got pretty bad in some races in 2004. I actually pulled the car out of the race at Road America about 20 minutes before the end, because Gunnar Jeannette was physically finished and David Saelens had driven to the point of collapse before I replaced him with Gunnar.

“I don’t want to say that Gunnar wouldn’t have been able to go on, in fact he insisted that he could. Even after I’d made the judgment call and had him lifted out of the car and sent to the race medical centre, I got called over to the ambulance because Gunnar was fighting the paramedics and saying he wanted to get back in the car and drive.

“Gunnar is an iron man and probably could have finished the race, but the people at the medical centre said, ‘No way, this guy can hardly stand up let alone drive a racecar’ ”

The Trans-Am version of the Esperante gave the model its first taste of competition success. Has the GT2 car got anything in common with that design?

“The Trans Am car was a purpose-built tube frame structure which was designed by Brian Willis, who is now Multimatic’s technical director, and the GTLM has absolutely nothing to do with that car, because of the rules in Trans Am that require a live axle and so forth. The GTLM is a GT car with the production geometry within the realms of the movement of the FIA/ACO rules.

“The suspension components are all bespoke items, the control arms, links and everything else were built by Multimatic. Some of the main components have been replaced, but they are in the same location. The differential, instead of being a Ford part, is an Xtrac racing diff. and the gearbox, instead of being the Tremec T56 that’s in the road car, has been replaced by a Hewland box. “

“The base engine is still the same modular Ford motor, but punched out to 5 litres and fully race prepared by Elan Power Products. The car has aftermarket halfshafts and prop, but all of those parts are where they are in the road car. From that perspective the road car has a lot of the same traits as the racecar. I liked the car so much I bought an Esperante for myself with a supercharged motor and it is a stonking road car.”

Which company handles the aerodynamic development programme?

“Aero for the ALMS programme has been done by EMT although Brian Willis did some coast down testing on behalf of Panoz a couple of weeks before the Le Mans test weekend.

“We had to try some new bits on the car because there was a difference of opinion with the ACO on our interpretation of the design of the front underfloor.

“The car ran in the original configuration in the early season ALMS races, but beginning at the Le Mans test, we had to block off part of the front diffuser. The straightline testing showed that we had lost around 20% of the downforce at the front end of the car and that was confirmed on the test day itself. The drivers complained about understeer in the high-speed corners like the Porsche curves.”

Obviously the highlight of Panoz Motor Sport’s 2005 season so far was the victory at Road Atlanta in April. What was the secret of that success?

“The Esperante GTLM race engine is a good strong power unit, but in the race at Road Atlanta in April 2005, the Porsches weren’t giving anything away to us on the straights.

"Robin Liddell (left) did a phenomenal job of driving to keep the Porsches at bay but it wasn’t like we were pulling away from them on the straights. A lot of it was in the handling.

"To that end we run to the 1200kg weight limit, at which we can use the GT1 tyre. That means that we run a bigger tyre than the Porsche, which suits our car a lot better. We have to add 25-30kg of ballast to do that but we feel it’s a good compromise.”

Even with the aerodynamic rule adjustment the Esperante GTLMs have continued to offer strong opposition to the Porsches in GT2. Are more class wins on the cards?

“I hope so. I think the Esperante GTLM is a good alternative to running a Porsche in the GT2 class. Porsche has been dominating this class since I was in short pants so it’s about time someone had a go at them.”