Hi all,

I'm curious as to if I'll need to get my car re-tuned or not. I have a 2000 M6 coupe that I had dyno tuned awhile back at 21st Century Muscle Cars in Addison (352rwhp/346rwtq on a dynojet). I was actually somewhat disappointed with the results because I see a lot of bolt on cars making 335-350 rwhp and my car has all the bolt ons (TPiS headers, Granatelli MAF, x-pipe, blackwing, ls6 intake, PP throttle body, Corsa Indy Pace Car exhaust, NGK TR-55's, SPEC stg II clutch) but also has a cam as well (comp cams 54-412-11) which is 212/218 .522/.529 114LSA. Granted... this is a baby cam (I would've went bigger and will be doing so soon, but I bought it this way) BUT I feel like it should still be good for more than only about 10 rwhp over stock.

Well, after the dyno tune I decided to change the spark plugs because I wasn't sure what kind of shape the current ones were in (I put the NGK TR55's on there, it had platinums on it before). While doing the job, I noticed that the air bridge was disconnected from the blackwing filter where the MAF is. I swapped my ls1 intake to a ls6 intake a week or two before the dyno tune and I guess I didn't tighten the rubber couplers from the MAF to the blackwing and MAF to the air bridge well enough. I must have hit a bump or something and caused the blackwing and MAF to disconnect from the air bridge... the blackwing was sitting at maybe a 30 degree angle from horizontal (viewed from the front) which is why I even noticed it, and then as I inspected it further I noticed the gap between the pieces.

This got me thinking and now I have a couple of questions...
What if this had become disconnected before the dyno tune and I had been driving the car with it like this since I did the intake swap? The tuner at the shop said the car was detonating when I brought it in and that it had way too much timing in the current tune. I guess I'm damn lucky I didn't suck up anything into the motor since the air wasn't exactly flowing through the filter while I was driving... If this indeed was the case and the MAF and filter were disconnected (plugged into the computer but uncoupled) during the dyno tune, could this account for my low dyno numbers? And, if so, should I go get the car re-tuned now that I have everything solidly tightened up? Or, if this were the case during the tune is it something that the shop would have been able to see while tuning the car (which would mean it probably wasn't uncoupled at the time of the tune)? The other thing I find odd is that my fuel injectors are running at around 88-90% duty cycle at WOT (they're the stock injectors for 2000's which I think are like 26lb). I would figure that these injectors should be good for up to 380-390 rwhp if the 28lb injectors are good for 400+ rwhp, but maybe I'm wrong... if this is the case though could it be related to the uncoupled MAF/air filter?

Looking for some input from the tech guys or anyone experienced with HP tuners (software that they use at the shop)... maybe I'm just expecting too much but I'd figure that 370-375 rwhp is a reasonable expectation for my setup at this point which is why I'm trying to think of explanations... not to mention the whole MAF/filter issue.

Thanks for the advice guys.

 

Lots of views but no responses. Any opinions?

 

How much would they charge for a re-tune? That would be the deciding factor for me. But if your planning on doing a cam install soon i would wait until then to have it re-tuned to save some money.

 

I'm just as lost as you are. My 2000 coupe has vararam, LS6 intake, LG pro headers, 227/230 640/604 111+3 cam, Corsa pace and only did 360 on the dyno when I was thinking it would at least do 385ish. I was told that the fact that it is an A4 killed it on the dyno.

 

Well crap... Now THAT is strange. I know an A4 will be low on the dyno but that's really low and that's a pretty stout cam. If I had to guess I'd say that the 853 heads are just suffocating the motor. Still, the A4 came with 2.73's or 3.15's in the performance diff either of which would produce higher dyno numbers than an A4 with 3.42's like the m6 or 3.90's...
That must be one stingy dyno unless it was a mustang dyno or the numbers weren't SAE corrected?

 

It would run me $100/hour on the dyno but I think it'd only take a half hour or so. I'm just curious if that could've affected the dyno numbers and/or tune that much.

I'm doing a head cam swap relatively soon but by that I mean hopefully by next year. If I had friends that knew what they were doing and space to do a swap myself I could do it much sooner but the labor cost is the killer.

 

I went on an above ground dyno jet. The guys at the shop had told me that it recorded lower numbers. I have the 315 gears and I agree that the 853's are choking me. A month after the cam, I had a 3000 stall put in and didn't even bother with the full dyno and just went with a street tune. I am extremely pleased with the outcome but am still perplexed by the recorded numbers.

 

Those dyno numbers are not bad for the bolt-ons you listed for an A4 car. If you had an air leak, the tuner should have found that. If they didn't I would probably question the entire tune.

Want more power? Swap out heads. You could probably find some used Z06 heads to get reworked and ported for another 20-30 HP with the correct matched cam of course.

The A4 tranny is robbing you of HP to the wheels. A good stall torque converter could help quite a bit.

Here is a good article on the difference the right torque converter can make.

http://www.corvetteonline.com/tech-s...que-converter/

 

My car is a M6 and it has bolt ons plus the cam... That's why I'm confused at my numbers. It was an above ground dynojet... I didn't realize that being above ground would affect anything.

 

After the higher stall was added, my tuner told me not to worry about dyno numbers but see what it did on the street. My uncle has a 2004 Z06 with headers, exhaust and a tune and my coupe stayed on the same level all the way. My goal was to get stock LS6 and Ls2 power and I feel that I accomplished my it.

 

Ah, OK. Then yes, those numbers seem a little low.

 

Does anyone have more info on this? Or info on why an above ground dyno would read lower than an in ground dyno?