Readers will be familiar with the work of Shane Tecklenburg through our past investigation of his involvement in Rod Tschiggfrie’s street-legal Sorceress drag car and of the turbo compound system he developed for Ralphie Navarro’s Nissan I4. Both of those projects are updated in the Grid section of this issue. Talking of turbo compound systems, we asked Tecklenburg: what scope do you see for those elsewhere in racing? “There’s a couple of different approaches to running a compound turbo,” he replied. “One is what we developed for Ralphie’s engine, which is not trying to widen the power band but is just trying to increase the height of the ceiling of peak power.
George Poteet’s Speed Demon holds the outright land speed record for wheel-driven, piston-engined cars at 470.733 mph (Courtesy of Marc Gewertz Photography)
“The other way you can use a compound system is to widen the operating range. Say you’ve got an operating range that needs to be between 4000 rpm and 10,000 rpm, and your existing turbocharger is really good up from 7000 but doesn’t perform well below that. So you add another turbo to the system, not to increase the power ceiling but to widen the operating range.” So that would be relevant to the challenge of Pikes Peak, where you were involved this year? “Potentially. I was at Pikes Peak to assist Pastor Don Wickstrum, who has his Redi/Axel Racing Riley LM P3 car fitted with a 5.0 litre Nissan VK50VE V8 twin turbo run by a MoTeC M150. Conditions were terrible: fog so thick you could hardly see 20 ft in front of you. Rain and cold. Nevertheless, Don made it to the top, which in itself was an achievement this year!
“For next year his team will have two cars, both the same. Then if we have a problem in testing or practice with one car, we can literally switch to the other. “As for turbo compounding, that can work in both directions at Pikes Peak – for increasing power and for widening the power band. That is because Pikes Peak is a special case, since as you go up the mountain the barometric pressure is dropping. “So you could compound for Pikes Peak to widen the operating range, which would give you more power at lower rpm – useful on the slower section. Or for more power. You could even put an extra turbo on your existing turbo engine so that the existing turbo thinks it’s at sea level all the time. That way you would have the exact same horsepower from the bottom to the top of the mountain. “If you wanted to normalise your power like that, you’d find a turbocharger that didn’t have to make a lot of pressure, that was just big enough to supply enough air to the existing turbocharger at sea level pressure and hold it there all the way up the mountain. “You would basically take the exhaust out of the existing turbo and feed it to the exhaust inlet of the additional one. Then you would fit a heat exchanger through which to feed its charge into the turbo that’s already on the car. Obviously there is that extra charge cooler and so on, but it’s literally like adding a turbo kit to an already turbocharged car. “You might actually find that you’d be better off if you made a bit more pressure with the first stage and a little less with the second to get the end result you want. But the general concept of it is, you’ve just added a turbo kit.”
We also asked: presumably you could provide the control needed for a compound system? “Of course. Surprisingly, the control system I did for Ralphie wasn’t really that difficult at all. Once I’d got the source pressure reading correct for the low-pressure wastegates it worked beautifully.” We also wondered if a compound set-up be would relevant to the Speed Demon at Bonneville? We last looked at the Speed Demon in RET 134 (September/October 2021). It is the single-seat streamliner of owner/driver George Poteet, which holds the current outright land speed record for wheel-driven, piston-engined cars at 470.733 mph over the flying mile. That record was set at Bonneville in 2020 using a Big Block Chevrolet prepared by Ken Duttweiler. California-based Duttweiler Performance prepares a range of engines for the Speed Demon, the others are Small Blocks so that the car can also shoot for records for classes limited to smaller displacements. All these engines are methanol-fuelled twin turbos with the charging system and many of the ancillaries shared for ease of switching the car between classes.
Shane Tecklenburg tunes the Duttweiler Performance-prepared V8 turbos that power the Speed Demon (Courtesy of Marc Gewertz Photography)
“No question a compound system would be beneficial for the Speed Demon, particularly when we run the smaller engines,” notes Tecklenburg, “We have been running a pair of 88 mm compressors on all our engines. So we are asking those turbochargers to supply enough air for not only a 555 cu in Big Block but for a 443 cu in, a 368 cu in and a 256 cu in Small Block. “The 443 and the 368 engines are just about perfectly matched to that 88 mm turbo in consideration of boost pressure versus backpressure. If you look at the mass flow into the engine compared to the compressor map, it climbs right up the middle of that map. And when you have a really good match like that, that’s when the magic happens. You get crazy horsepower numbers. “The problem with the 555 engine is that it’s way off to the right of the map; it uses way more airflow than an 88 mm turbo can supply efficiently. So what we have is hotter air that takes more drive pressure on the exhaust side to get to the same place. We’ve got more back-pressure and hotter charge air.
“Then we have the 180º opposite of that on the 256. There, we’re off to the left of the surge line in the first part of the run. So it’ll surge whenever there is gear change until it gets to the rpm where the engine can swallow everything the turbos are delivering. “The ‘bush fix’ for that we came up with last year was to take the wastegate source fittings out of the compressor housing; those lines would normally supply pressure to the bottom of the wastegate. We connected them to the intake plenum so the wastegates could operate normally, but we literally left the fittings out of the compressor housings so that the compressor had a leak to atmosphere.
The Speed Demon swaps engines and hence class between record attempts at Bonneville (Courtesy of Marc Gewertz Photography)
“With that leak we were able to move the airflow range to the right on the compressor map, away from the surge line enough that we could run the boost where we needed to have it and not have surge on gear changes. “So we know that the 88 mm turbos are too big for the 256 engine. But the record for that class isn’t as important to us as going 500 mph. So we spent our money on turbos for the 555, and next year we’ll have 98 mm turbos. And again we’ll just run the little engine with leaks coming out of the compressor housings to abate the surging on gear changes with that engine. “We have a new set of 98 mm turbos coming from Precision Turbo. I took all the data and worked back and forth with Dan Barlog [the engineering director] of Precision Turbo to come up with the right compressor and turbine, matching housing sizes and the A/R ratio and everything else for the 555. Hopefully with those turbos that motor will run the way it should, and we will make 500 mph.”
Horsepower and charge cooling
What sort of horsepower are we talking? “When we ran a 481 mph exit speed 2 years ago we had 38 psi boost from the 88 mm turbos, and that calculated to about 3800 bhp. But our struggle is that we run out of capacity in the charge cooling system before the fifth mile. “When we are running the 555 the charge temperature rise means that after the fourth mile we’re having to put in place countermeasures to try to keep it from blowing itself up, like taking timing out and richening it. To that end, although we have 3800 bhp worth of air we are not able to sustain a power output of 3800 bhp. That means we’ve run out of power after the fourth mile. “Our hope is that the 555 will be more centred in the compressor map of the 98 mm turbo. So that will mean we shouldn’t have the charge temperature go crazy before the fifth mile. That will automatically give us some more horsepower. “Our other hope is less back-pressure with a larger exhaust wheel. That will mean we make more horsepower with no increase in boost. And then beyond that, because the 98 mm turbo is so much bigger, we will also have the capability to turn the boost up more.
Tecklenburg tunes Don Wickstrum’s Riley-Nissan twin turbo Pikes Peak car (Courtesy of Damon Steinke/E3xtreme)
“We know it’s going to take at least 10% more horsepower to go 500 mph. Given that there is no longer a need for countermeasures after the fourth mile, plus lower back-pressure and a lower charge temperature, we hope we can attain that speed. If not, our back-up is to raise the boost until we get to the same point operationally. “So long as we can make it last 5 miles and get our 500 mph we will be happy!” So you don’t necessarily think a compound is called for here? “It would be difficult, given the Big Block, to find the space to put a compound system into the Speed Demon. It would also be difficult to come up with big enough turbos to supply the demand of that engine as a compound. It could be done though, but at this point we’re so close to 500 mph that we are reluctant to try something new.
Solving problems
“Last year we had technical problems. We’ve addressed all those issues but this year we missed our chance because of the weather and salt conditions. When this year’s attempt was cancelled, instead of switching to other projects I took the data back home and combed through it. I don’t want to go back next year with any known problem. “I knew we had some data channels off by a decimal point. But because we always have other bigger problems going on at Bonneville, such things don’t get addressed. So I spent time combing through the software and I fixed a number of things.
Tecklenburg tunes Derrol Hubbard’s D Bar D Racing Camaro. Unfortunately, shortly after our conversation it had an unscheduled meeting with the wall that left it badly damaged (Courtesy of Damon Steinke/E3xtreme)
“Then there was the question of the fuelling. The Speed Demon has a combination of mechanical fuel injection and EFI. That is because the first MoTeC system they introduced was only capable of driving eight injectors. So Kenny [Duttweiler] came up with a hybrid set-up whereby he just turns on what is effectively a wet nozzle – like a nitrous enrichment nozzle – that sends fuel to the mechanical injectors. “Then, in order to get the engine to run right, you trim the EFI side by a percentage of the amount of fuel you’re adding with the mechanical system. In other words, if we have 2000 horsepower worth of fuel going into the engine, and 500 horsepower worth of it is coming from the mechanical nozzles, you trim 25% away from the EFI side and the mixture ends up at the right place. “The problem with this percentage method comes when you change the operating parameters. For example, when you turn the boost up the EFI system tries to linearly deliver more fuel volume to the engine based on that change in boost. But because there’s a mechanical system that can’t change you end up short. The EFI system doesn’t know anything about how much fuel the mechanical system is delivering.
“So I have now changed the code in the ECU so you can enter the fuel volume that the mechanical system delivers. The EFI system will henceforth subtract that fuel volume away from what its calculation is. So now, if we indicate that we have turned the boost up, the EFI system knows it needs to add more than just what it thinks it should add in its own right. “I am currently testing the mechanical side to measure exactly what that supplies. So in future, when we make changes, this will help us ensure that the engine will have the correct air-to-fuel ratio under all operating conditions, regardless of whether closed loop feedback is active or not.” But now that you have the contemporary MoTeC M150 system, why retain the mechanical side? “We could run all-EFI now, no question, but when we put the M150 system in we were trying not to completely upset the applecart in as far as what we had already been running. If we had replaced the mechanical side we would have had a learning curve to figure out.
“And we wouldn’t have had the opportunity to test that change on the dyno. It didn’t make sense to convert it if we weren’t going to get a chance to test it, so we kept the set-up we knew. And now that I can calculate the correct air-to-fuel ratio adjustment I’m not sure it would be any better with all EFI nozzles from the fuel delivery standpoint. “Also, when I started with the Speed Demon in 2016, I felt it was probably not in my best interest to show up with relatively little Bonneville experience compared to the many years of experience they had and tell them what they had to do. Instead, I said, ‘Let’s keep running what you were already running in the old car, let’s just refresh it, update and modernise it a bit.’ “I’ve always kept that attitude, because now I understand how it goes every year. George has lots of resources and we’re all capable, but we’re not a team that is on his payroll all year round with our only focus being that car for Bonneville.”
Knock control
When we last investigated the Speed Demon, there was talk of introducing active knock control. Did anything come from that? “Not yet. The problem is you have to characterise it. To do that you have to put the engine into knock to be able to decide what frequency gives the best signal-to-noise ratio from the sensor. And we just don’t seem to ever find the time to be able to do all the things we want to do. “We had a struggle last year with oiling control for all our engines. Time was spent addressing that problem, which I think we have fixed now. So we didn’t get chance to look at the knock stuff. We always have great ideas of what to do for next time, but implementing all of them isn’t feasible.” Turning back to the world of quarter-mile racing, Tecklenburg reported, “In NHRA this season I’ve been working for Lee Hartman’s Factory Stock Showdown team. He runs a Dodge Drag Pak which has a 354 cu in Hemi, and we have one of my MoTeC M150s running it. This class races on a radial tyre, which brings its own challenges. “Ultimately it is all about power management. You are trying to read the track correctly, to not overload the tyres and then to have enough horsepower to make a good run.
The D Bar D Camaro has a methanol-fuelled 521 cu in Brad Anderson Hemi twin turbo (Courtesy of Damon Steinke/E3xtreme)
“We have the horsepower part thanks to our involvement with Darren Mayer Performance Engineering. Darren and I have been tag teaming it all year on the tuning side. Recently we had some additional consulting help from 2022 NHRA Pro Mod Championship winning crew chief, my good friend Jamie Miller on the suspension side which paid off with a new personal best of 7.776 elapsed time at the final race in Dallas which qualified us sixth. “So I’ve been doing that this year and also working with Derrol Hubbard’s Mid-West Drag Racing Series Pro Mod team D Bar D Racing. He was running the West Coast but decided he wanted to run against some of the best, so he moved his facility to Oklahoma, from where since last year we have been running the entire Mid-West series. “Currently driven by Ed Thornton, this car was the world’s fastest 88 mm turbo Pro Mod. It is a 1970 Camaro with a methanol-fuelled 521 cu in Brad Anderson Hemi twin turbo, now with 98 mm turbos and run by an MoTeC M150 system. I have implemented custom software that runs four injectors per cylinder. “In this series, turbo cars present a problem in that they can’t make the same downforce at the front compared to supercharger and ProCharger cars. So you can’t put as much initial bite into the rear tyres, which means you are not as quick when you leave the starting line.
“But our twin-turbo Hemi makes a ton of horsepower, and you can hopefully put enough of it down after it leaves the starting line to make up for that. At most meetings, we run the top speed and we ran the best ever speed of 222 mph in a race in Tulsa in October. “We have a billet intake manifold of my design, which distributes air very evenly to each cylinder to the point that, along with our Injector Dynamics injectors, we require zero trim in order to run at the same air: fuel ratio in each cylinder. “But our car was not designed for what we are using it for. It was built in 2005 as a ‘68 nitrous Camaro for Rickie Smith, so Derrol is planning over the winter to replace it. That will be for a modern turbo car with a purpose-designed chassis with the engine in the right place for the turbo combination and a much more rigid chassis. Right now, over the eighth-mile we are about five to seven hundredths [of a second] off being able to win consistently. So we are hoping we will make that up with the new car.”
SHANE TECKLENBURG
Shane Tecklenburg is the son of an autoshop teacher and drag racer. As such, early on he gained an aptitude for mechanical things, and when he was old enough he followed in his father’s footsteps, working for Pro Mod drag racing teams including Woppado Racing and Kuhns Racing. In 2001, he became lead engine management system calibrator for MoTeC in the USA. In that capacity he worked in a wide variety of American motorsport disciplines, including drag racing, land speed racing, high-level road racing, off-road racing and even offshore powerboat racing. Since 2006, he has been an independent consultant specialising in all aspects of set-up and calibration of MoTeC electronics, as well as offering wider advice on the running of race vehicles. This is done both in person at the racetrack and remotely over the internet. When NHRA Pro Stock switched to EFI he helped Elite Performance and Gray Motorsports to make the switch. He was subsequently part of the team when Elite ran Pro Mod in 2019 with his custom MoTeC M150 firmware in both Erica Enders’ and Steve Matusek’s Mustangs.
In fact his list of successful collaborations with strip, circuit and off-road outfits is far too long to list in full here. He highlights though, “I currently consult with Modern Racing occasionally on Lyle Barnett’s Twin Turbo Pro Mod – still running my firmware – and client Rick Hord, who also uses my firmware in his Pro Mod. I have consulted exclusively with Vance & Hines Motorsports since 2003 in NHRA Pro Stock Motorcycle, a relationship that has been in place for near 20 years and one which I cherish dearly.”