After organising our latest development car it was a long an impatient wait for the week it was 'coming'. She fits in nicely with the strong American GM theme that we currently have going on in the shop.
For those that want to know the specs, the car (truck?) is a 2002 Silverado 1500 series of the short wheelbase kind. With a full fibreglass back section its not as heavy as you might think either which will mean lots of tyre smoking twin turbocharged fun.
The engine is a 5.3 litre version of the LS1 with that familiar looking big truck manifold and a fly by wire throttle body. There is some extreme torque management in there to protect the driveline, but still she pushed out 185rwkw on the obligatory 'before' run....now its time to get SERIOUS.
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Spending more development time on the Gen-TT GMC Truck systems, we have designed the fitment around the 2500 series and 3500 series HD AWD cars, so one product fits all. Props to the guys for spending the hours and getting the hard yards done.
We have managed to lay the intercooler on a 15 degree angle which means we can still mount it above the level of the transmission crossmember, and front lip while still giving it sufficient airflow, all without modifying the body structure in any way.
We have mounted the twin GTDW2833 turbochargers alongside the sump but with excellent rail clearance for the torsion bars and driveshaft of the 4WD variant. They are nice and stealth here, and have excellent ground clearance (above the level of the transmission crossmember yet again). Note there will be a complete Y pipe for the kit with the exhaust, the twin outlets are just a test piece.
The engine bay looks as stock as it did before save for the intercooler discharge pipe which runs back up to the Drive By Wire throttle body, and still gives enough room to retain the stock fan assemblies.
If you look at the Silverado from the front there is excellent ground clearance, and the promise of 100% torque and power gains on offer from the Gen-TT GMC Truck Intercooled Twin Turbo System.
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Having broken into the low 10s with a 10.28 second pass in less than ideal conditions at Heathcote during the LS1 Drag Nationals, Gareth has spent some time planning the next stage of his track assault. Follow this story to see Gareths progression.
The aims are simple -
- High to mids 9s on the 4L60E auto to make it the fastest 4speed in Aus
- Remove the 4L60E if there is anything left of it
- Install Turbo 400/Brake
- Spray 200hp of gas
- Try and run an 8 / 155 - 160mph with the factory IRS
Preparation for running these kinds of times has come with a fresh 346 cube alloy block engine from Rhemac Motors (who are sponsoring Gareth on his track quest). Des from Rhemac selected some nice forged pistons, a matching rod, a cam grind we designed 'in house', and then carefully blueprinted and machined the engine to take a big does of boost.
** This engine runs 10.1:1 compression (stock) and uses stock GM metal head gaskets
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Turbocharger selection will be our standard off the shelf Gen-TTR offering, showcasing the performance of the product we offer for sale rather than making a one-off for the application. Obviously to achieve the power levels required to run the times the turbos will be pushing around 20psi of boost .
This car will be light, still running the three plastic side windows that it had at Heathcote, and with a fully stripped interior. It will however not be insanely so as the turbocharger system adds 50kg, the new nitrous system around 20kg, and the line locker/other engine ancillaries say another 10 - 20kg. When the T400 goes in thats also a huge lump of metal to lug around.
Lets make it clear though. This car wont be run under the guise of being a daily driven streeter. It will be a stripped out rat chopped out of an ordinary and average condition VX. We will not tell you it runs on pump fuel, instead it will gulp down huge amounts of expensive exotic race fuels. Nitrous will not be added under the conventional guise to 'just to spool it up off the line' instead Gareth is going to spray this bullet as hard and as long as he can, and if the engine comes apart at the seams we build another. No smoke or mirrors. Thats the truth of it, and we love the idea.
Thanks to Rhemac Motors, and MV Automatics for getting behind this one with us, and being part of the LS1 Turbo development team.
** Update - 6/10/07 **
Today was an extremely fruitful day or research and development for us down at the LS1 TURBO R&D centre. We achieved something special, running a 346 cube LS1 with pistons (JE) and rods (Eagle) on Methanol using low impedence 160lb/hour 'Bosch Indy' injectors through the standard LS1 computer, and doing so in perfect fashion. We believe this is the first time such a thing has been successfully achieved anywhere in the world.
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This is a very soft tune, very low on the spark, very low on the boost, and, well perfect on the mixtures. In race trim we will expect to see another 70 - 90rwkw from it (12psi run shown, 20psi potential....), however the driveline and the 4L60E A4 transmission will be the deciding factor in that.
The original 390rwkw graph (black line) is on BP Ultimate, and here is what the correct application of Methanol can do (red line) for a boosted engine (over 100rwkw at some low rpm areas). Never will you see driveline shredding torque like this without twin turbochargers and methanol. Sure you use over twice as much as gasoline, but Methanol is only around $1 per litre....where a good race fuel approaches $10 a litre. The good news is swapping over to a 'petrol' program is only a flash tune and 20 seconds away.
The massive power and torque differences even at 3000rpm are staggering. Keeping the car on the dyno was almost impossible even with an automatic transmission. Our calculations mean that swapping to this fuel and tune should net us another 10 - 15mph at half track and Gareths car into the serious 125mph 1/8th territory.
Thanks to some of the guys that loaned their experience in the setup and tuning of the project. Sam from Sams Performance....a vastly experienced tuner at all levels with most anything. Jake from the ACT...what this guy doesnt know about 1000rwhp Methanol burners doesnt matter.
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** Update - 21/10/07 **
Now we are back home its time to reflect and analyse the results of our Heathcote weekend with Gareths car. The positives are that the engine and Gen-TTR Intercooled Twin Turbo System are running superbly, and when the conditions are in our favour, 150mph should be guaranteed without too much fusser to Heathcote.
Trying to make the 4L60E go this fast, and run a 9 second card isnt easy, and takes more setup and practice than us 'twice a year racers' from South Aussie have access to. Knowing that the trans was very finite (from looking at some looking which would show 800rpm - 1000rpm flare on the shifts) I didnt get Gareth to stall the car too hard which resulted in 1.75 odd 60 foot times. Still not to bad to run a 10.1 from a 1.75 60 though.
The quickest run of 10.1 was done just as the 4L60E clutches were starting to suffer in the heat of the day at near on 31 degrees air temperature and 996Mbar of air pressure, which in drag racing speak is 'bad air', so no, we certainly were not weather assisted at any stage.
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The good part is that now we have some data on the car and know exactly how it runs in these kind of conditions, which points us in the right direction for some top results next time out. 9 seconds and 150mph through the A4 is the goal, and with some more track time we will certainly have it.
Still, fastest and quickest 4 speed auto LS1 in the country is something to take away from the meet, considering the car runs stuff like a stock LSD, stock heads, stock inlet manifold, and best of all the stock 5.7 alloy block at stock capacity (a cause I have been championing for years!)....and a stock $7995 Gen-TTR Intercooled Twin Turbo kit. Nothing exotic, nothing different to the product a customer buys. Its quite scary how powerful these engines really can be with the right kind of boost pumping through them.
Work is well underway on GenTT BOSS at the moment, which will give the Ford Modular guys a good option for the small PD blowers and Centrifugals they have at the moment.
There are some real surprises in store on this one. Aims are a nice comfortable 380rwkw at 10 - 11psi with conservative tuning, and the ability to crank these big busses into the 10s without breaking the conrods, or the bank for that matter!
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** Update - 24/09/07 **
There are a number of contributing factors that add up to the Boss engines unusual normally aspirated power delivery. The main issue is the use of a Triton truck bottom end with a super long stroke (that doesnt want to rev) and a set of Mustang 4 valve heads equipped with camshafts that want to scream beyond 6500rpm. In other words just as the things get going they bounce the rev limiter
Where the Boss engine excels is at the upper reaches of the rev range in a forced induction application where the whole inlet and cylinder head package comes on song and makes big numbers. The four valve heads are enough to offset the lack of 600cc versus the Holden in the outright power stakes once boost is added...however that isnt the important part of the Boss story
Filling the torque hole down low and having the engine come on hard at 2500rpm is the key to making anything fun to drive, which is an affect you wont get with a centrifugal blower on a Boss, and only partially with a low boost belt driven type lobe blower that exists for these things. This, the neat packaging and silent integration is where we see the major benefits of our Boss Gen-TT Intercooled Twin Turbo system
Progress is looking good.
** Update - 30/10/07 **
Ok here are some pictures of the Gen-TT Boss Intercooled Twin Turbo system as it stands today.
Most of the pipework is now finished and is very well integrated with the overall packaging in the Falcon engine bay. As you can see its extremely stealth, and when you lift the bonnet there is very little 'in your face' about it other than the inlet pipe which runs up to the factory throttle body.
The twin billet blow off valves along with their silencers are located on the underside of the inlet pipe to keep the Gen-TT system nice and discreet.
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The inlet piping fits neatly behind the front bar and then routes up under the headlight with zero cutting required to the bodywork. Its very simple to route and fit so there should be no complexity there.
Under the car the cold pipes from the turbocharger to the intercooler are tucked neatly out of the way and give a direct shot at the cooler core.
We have mounted a Bosch Motorsport fuel pump in line with the stock fuel supply system to give adequate fuel in the tuning stage...which now isnt that far away.
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One for the motorcycle enthusiasts - After having been in the initial research and planning phase of a Gen-T single turbo system for a European performance bike specialist, we have just been given the green light and had a new BMW K1200S delivered (interestingly enough with Acro exhaust already) so that the project can get underway as soon as possible.
Our plan is to develop an intercooled single turbocharger system using a specially tooled version of the GTDW2828 liquid cooled turbocharger. There are obviously some interesting design constraints and packaging involed, along with the requirement to retain the Bosch Motronic engine management system rather than swapping to a simple, yet less effectvie PC3. Will keep everyone informed.
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** Update - 29/10/07 **
Today we had the BMW K1200S on the dyno for an initial 'pull'. Strapping a bike down correctly on the dyno takes a little bit of thought, particularly when it makes pretty good grunt like the Bimmer, but sure enough the Dynomax 450 was well up to the task.
After researching the kind of power a K1200 with a pipe (in this case the Akro) makes on a Dynojet we came up with between 155 and 162rwhp. We set the dyno using the most suitable ramp and inertia rate (in this case Shoot_6) to allow a good clean acceleration run without any traction problems...all the way to 10,000rpm.
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