RD in SD

I have an 06 A6 road racing car with a ERL sleeved LS2 434, L92 West Coast ported heads, Comp Cams 231 Intake 247 exhaust 617 and 624 lift and 113 lobe centers, Vararam, LS7 Throttle Body and injectors, FAST 102MM intake, Melrose 1 7/8 headers, hi flow cats, stock Z06 Mufflers, It also has 3:15 gears and Quaife diff. The cam and other parts were choose with road racing in mind and a wide flat toque curve.

I put it on a Dynojet dyno today and I was surprised that the horsepower was only 466 and the torque is about 477. The torque and horsepower curves looked to be about what I expected but I thought horsepower would be over 500 even with the automatic. I kind of pieced the car together with left over stuff and the headers are 5 years old with some small dents and old cats. I was wondering if the old headers, cats and stock Z06 mufflers are holding me back. Also what about the throttle body? Anyone have comments or ideas?

In addition we can't make it start without cracking the throttle so my dyno guy drilled a small hole in throttle plate but we still need to crack the throttle just a bit to get it to start. Anyone have any ideas on this?

KLLRVET

Find a different dyno guy. Drilling is NOT the way

Mike@DiabloSport

Yeah, the tune needs some work for sure, but I'm not convinced the numbers are that far off with an automatic. What RPM did it peak at, and did power fall off quickly after it peaked?

DSteck

That idiot ruined your throttle body. You need to get the car far away from him. He clearly doesn't know what he is doing.

If you have HP Tuners, I will help you out once you put a new TB on without a hole.

RD in SD

The power peaked at about 6000 and did not drop off sharply it was just a bit lower at 6600 which is high as he went.

dubseven

Drilled the throttle body? Seriously? Was it his first day on the job?

Frans96ss

haha seriously... Tell him to go back to 1998

Zip Corvettes

Not that long ago I had a car in here that had some idle/low speed driveability issues that was from a very known tuner on here, and it had a drilled throttle body. First step in getting the car right was to replace the TB with a new one. I was shocked as they have been in magazines talking about there tuning abilities.

CTD

JB Weld can fix it up nicely & yes their is no point in drilling the blade.

Holy gents full attack...yikes....

Zip Corvettes

I would say to have it tig welded before you use JB weld. What happens if the JB welds comes off? In the end it will cost allot more than what a new TB costs.

FloydSummerOf68

Any update to this tragic tuning incident?

CTD

Very unlikely if you chamfer the hole little. This has been done many times tuning carbs, strictly trail & error to get blade correct with the transfer slots. No software Then we would drill the JB to get it right

Carbs you have fuel added to the mix & JB is very resilient to that, so I'm sure with just air passing across the blade no fear mongering is warranted.

0Cunningham Motorsports

there is no need to drill a hole in the tb.... that is just laziness to do that.....

RD in SD

No update yet tuner is working on it. I did find out that the 09 LS7 throttle body I put on it is not compatible with the car. Putting the LS2 back on it now. I should know more tomorrow. I do appreciate all the input.

Zip Corvettes

too much risk, not fear mongering. If it did fail, JB weld will not burn well in the cylinder and it might not just get pushed out. If it lodged in a valve as it was closing the damage would be catastrophic. In end the replacement engine would be allot more expensive than the replacement throttle body. I call that being smart on a part that is not worth being cheap over. Personally that tuner that drilled it should be putting a new one on, not the owner of the car.

MIGHTYM0USE

probably in the tune. safe bet nothing wrong with the hardware unless you let the same guy install it.

edcmat-l1

I'd put a 102mm throttle body on it. They're proven to make good power on the bigger motors.

Might want to check the cats too. I've seen blocked up cats kill power more than once.

And find someone who knows how to tune these cars. There's absolutely no need to drill a TB. A couple simple adjustments in the tune and it will start up just fine.

SpinMonster

JB is not ethanol or methanol resistent. I tried repaing a meth tank with it. It will become brittle at which time it cant do any damage to an engine but then its not effective in repairing TB blades. I've done it before for those who wont buy a new TB but it comes with a warning that you cant have oil or meth going into your intake tract....IE no meth injection as the meth is sprayed at the TB blade where on carbed cars fuel is after the blade.

If there is no oil or meth getting on it, it will hold up for a long time.

Pics from actually doing it:




For those of us who were tuning C6's in 2005, HPtuners wasnt to market with anything that allowed airflow table alterations so for 9 months it was LS2edit and you had to drill holes. It wasnt a 1998 issue only. Any cam over 232 intake durations was in need of airflow at idle and start-up.

0Cunningham Motorsports

still to this day the 05 e40 cars can be a pain to get started on big motors the startup airflow table isnt quite as effective as the later computers, but 06+ e38 cars are easy..... that has been my consensus however , i have tuned quite a bit of big motored cars...

SpinMonster

All that huge split does is add overlap. A 434 has no issue with raising compression so a 231/238 115-1 or 116+0 would have made the same power with 1/2 the overlap. The reason LS3s have a need for a tight LSA with a big split is that they cant run any real compression with the L92 heads big combustion chamber. The early intake valve closing point of the tight LSA helps low end TQ while the big split extends HP past the HP peak.

A 434 that can run real compression can ditch the big split and widen the LSA to make power higher into the RPM band with more compression to make up for the later intake valve closing point. A 231 on a 115-1 peaks at 6300 coincident with where the intake manifold forces the HP peak. A 231 113 is peaking way too early in a 434 and is why you had the poor result. It would peak at 6300 in a 6.2 liter.

I wont waste time talking about ported L92 heads as I've never seen them make good power on any motor (unless advanced induction carbed motors running race gas counts).

Trick Flow 235's on a 434 will beak over 600rwhp as will LS7 heads but theres the cost factor which is always the next sentence when talking about ported LS3/L92 heads.

Existing cam overlap= 13 degrees
231/238 116+0 overlap= 2.5 degrees
231/238 115-1 overlap = 4.5 degrees

Coupled with 11.8:1 compression resulting in a 8.6 DCR on that big a motor will run, start, and idle like a 6 liter with a Z06 cam. Easy starts and no airflow issues from low vacume. Even at 13 degrees overlap, it should be starting and running smooth at that displacemt. Your start-up issue is fixed by increasing the startup airflow table. Start with a 10% increase.

Was that cam left over from a smaller displacement build?