kinda a hotly debated subject, ive seen arguments both ways but ive kept mine on due to the crappy New England weather and at my power level i doubt it would be a noticable difference. at the 600rwhp level, i heard 10-15 hp can be picked up but an extra PSI out of the turbo would easily do that too

 

can we get some more details on your setup... please...

 

Mods in sig, plus a ball bearing t67/t4 and log manifolds, like the kits from realquick. I kept the A/C and didnt move the radiator. Only running my stock fan on the passenger side right now, im going to have to do a pusher fan on the driverside.

44mm tial wastegate and a 50mm tial bov, 5lbs of boost.

 

stock motor? what are you doing for tuning? i might end up mimicking your setup...where did you get the log manis?

 

Stock bottom and and 5psi for now. Ive got a block in my garage i am working on.

Best bet for the manifolds is to get them from realquick. www.lt1boost.net my logs look really similar to his I would have gotten them from him, but im impatient and didnt want to wait. I ended up getting all my bends from summit. And had my head flanges water jetted at a local machine shop.

Im using LT1 edit and I have a base tune with 25* timing and drove it around a good bit today logging with the datamaster. Good news. I was not getting much knock retart at all. just a couple instances in a 15 minute drive.


The most I got on it was 66% throttle to 4000, rpm. My injectors were at 70% duty cycle so i deffinatly need something bigger than the 30#s I have (i knew this, just trying to find a deal on some). I dont have my boost sensitive fuel pressure regulator in yet either. Reading OK on the wideband for everything so far



What gears do you think I should run, I think the 4.10s I have now are a bit much. Im not sure If I should go all the way down to a 3.42 or do a 3.73

 

3.42's, the lower the gear the longer you have to build boost and stay in boost. you have an A4 right?

 

M6.

 

durr, sorry im in the middle of like 4 cars... with both trannys being either a A4 or M6
3.42's would still be the better bet imo

 

I have heard a few people with issues, but most people find a large gain in HP and responsiveness. I can only imagine that with a boosted car that extra power and responsiveness is even bigger.

It also is what one of the largest LT1 tuner's reccomends, but just my .02 cents

 

I'd recommend the 3.42's as well.

 

id say 3.42s(im bias because thats what i have stock )

 

Im having an issue with the car being lean at idle 16-17:1 and full lean when engine breaking. Im not sure whats up. The wideband is new, for all I know its always been like this.

This sound like it could be an exhaust leak or vacume leak? Car seems to idle ok, fluctuates a little bit, dont think I can hear any exhaust leaks.

I IAC counts arent going down to zero which would indicate a vacume leak.

The instant I touch the gas it goes down to 13:1. Cruising its fine.

 

When you decel the injectors basicly like shut off. My wideband reads full lean on decel too. But my idle is right on 14.7-15:1. Cruises at about the same. 11:1 WOT.

 

well that explains the decel thing.

 

Yep it'll go lean on decel, I'm not familiar with lt1 edit, but on tuner cat their is a table to adjust that setting.

As far as lean at idle, how much fuel did you add at idle? I added 25% on the initial startup tune and it put me right at 13.5:1 AFR. I'd add in some more fuel, your lowest settings on your maf are probably just too low.

25 degrees timing is fine at part throttle, wot tho I wouldn't run that much on a stock motor. I ran 16 degrees max(most say it's too low and to run 24-25 on pump) but honestly why chance it, especially with your stock pistons.

Lastly, be careful not to peg that maf, you can adjust the last cells in the table up to 512, but that is as high as you can go. 5lbs I'd think you would peg it though, 6lbs pegged mine and that was with stock heads/cam, but I am running a T76 vs your T67. Just watch it and make sure it doesn't max out.

Lastly, check out the tuning section on here, you might want to convert to a 2 bar map tune.