kennysta01

i have a 2001 trans am with an 03 6liter. it has been built by a local machine shop, it has stock crank, melling oil pump, new timing set, eagle 6.125 h-beam rods, weisco 12cc dome pistons, bored over .030, faST 102MM INTAKE, godspeed(ebay) 102mm throttle body, longtubes, pacesetter y-pipe, magna flow muffler, heads are gm 317s, 2.125 valve seat, 2.08 in, 1.60ex, mild hand ported and polished, ms4 cam, prc gold springs, pi 3600 stall, comp pushrods, partial tune, gm 85mm maf, fast 46lb injectors, tuner redlined at 6200rpm, the motor is tight and needs to be broken in. with the mild tune it only put down 350rwhp. what could be wrong? it is being tuned at the chevy dealership. can someone please help? i was expecting around 480.

2xLS1

iTrader: (25)

I've never known a dealer to have a dyno. What kind of dyno is it? Can you post a picture of the graph?

89 formula350

iTrader: (8)

what do you mean by mild tune? I second the graph picture. might say alot on whats happening. hows the car feel.. any lag in the power band?

kennysta01

I don't have a graph yet. My tuner has left the country for spring break. He will be back on the 27th. He called me and told me the news before he left out. He hasn't tuned the transmission yet. Could that be the problem? The car seems to run fine. The only problem is you have to press the gas for it to start. After that it idles around 850. He said it was hard to tune so far. That was the first dyno run at 350HP. When he gets back I am going to go up there and see if I could help him so I am hoping I can gather some insight before that.

Old Geezer

iTrader: (3)

If it's been on a dyno and driven, it's as "broken in" as it's going to get.
If the trans doesn't slip, it's likely not the issue. The converter, maybe.

When you get the dyno sheet[s], get the tune file and data logs, too.

redtan

iTrader: (5)

Tuned at a chevy dealership? You mean they're putting the stock tune on your rather modified car?

And idk if I would expect 480rwhp out of a stalled 370ci with GM heads.

SSpdDmon

iTrader: (10)

Are the 317 heads milled down at all? If not, won't that lower compression? That'll cost you some power if so.

It sounds like there's a tech who works at a dealership that might be doing this on the side. If so, how experienced is he in tuning cars? 350rwhp on a 6L with an MS4 would raise significant questions IMO.

If I'm wrong and it's a legitimate tech putting a stock tune in your car, you better start saving for a new motor...

thunderstruck507

iTrader: (18)

Lots of questions worth asking have already been asked, but if you are expecting 480rwhp from that combo you are going to need the happiest dyno you can find to even get within 20rwhp.

Looks like a 430-440rwhp combo to me with all the bugs worked out.

I sure hope the dealership has someone who actually knows aftermarket tuning with EFI Live or HP Tuners or you are going to end up with a big paperweight shortly.

kennysta01

For the first question, the heads aren't milled but I am running 12 cc dome weisco pistons. The compression should be around 11.7:1. The tuner works for a GM dealership for GM. They have a dyno not sure what brand. He does tuning for aftermarket parts for new cars. He is currently on vacation and will return on the 27th, and hopefully I can get more info and I am sure I will have some questions. I was hoping someone would hook me up with s base tune to look at and compare his tune to when he gets back. Thanks so far from everyone who has given there input. Also, what kind of mechanical problems could cause this? The motor sounds perfect.