Precision 76GTS pictures with stock radiator
07-19-2011, 03:57 PM
#21
I think my next upgrade will be a cut-out like yours.
Do you think the gains would be worth doing a 3.5" or 4" cut-out? I have 3.5" DP and 3" exhaust all the way out. The 3" would be easy to do in the I-pipe, doing the it on the 3.5" section of the DP would be very tricky.
If I just welded in a piece of 3.5" or 4" tube like you did (short piece) in my 2' long section of I-pipe I could do what you did.
What were the gains that you saw on the dyno if you have dyno'd it closed vs. open?
Do you think the gains would be worth doing a 3.5" or 4" cut-out? I have 3.5" DP and 3" exhaust all the way out. The 3" would be easy to do in the I-pipe, doing the it on the 3.5" section of the DP would be very tricky.
If I just welded in a piece of 3.5" or 4" tube like you did (short piece) in my 2' long section of I-pipe I could do what you did.
What were the gains that you saw on the dyno if you have dyno'd it closed vs. open?
07-19-2011, 04:39 PM
#22
When I was on the dyno I was just diagnosing my misfire issue, I wasn't tuning it at all. It was at 10.0-10.2 AFR. Turns out my stock coils were junk, if you look close I have D585 heat sink truck coils now. I honestly forgot to dyno with the cutout closed 
When I was N/A I gained 17hp / 14 ftlbs through out the entire curve with the exhaust open vs being closed. I will redyno my car with this turbo when I get my new wastegate, I can get on it anytime since I tune the local LSX cars in the area and am friends with the dyno guys.
There is a noticeable spool difference with the cutout open, seems to spool much quicker. I doubt there are much if any gains with my 4" cutout vs a 3.5" cutout, I just did it to future proof myself in case I ever end up with a 4" downpipe in there. You should check out NicD's setup, he went 151.7 mph with a 3" down pipe on his 76GTS, his turbo is maxed out from what he told me https://ls1tech.com/forums/forced-in...-new-best.html
When I was N/A I gained 17hp / 14 ftlbs through out the entire curve with the exhaust open vs being closed. I will redyno my car with this turbo when I get my new wastegate, I can get on it anytime since I tune the local LSX cars in the area and am friends with the dyno guys. There is a noticeable spool difference with the cutout open, seems to spool much quicker. I doubt there are much if any gains with my 4" cutout vs a 3.5" cutout, I just did it to future proof myself in case I ever end up with a 4" downpipe in there. You should check out NicD's setup, he went 151.7 mph with a 3" down pipe on his 76GTS, his turbo is maxed out from what he told me https://ls1tech.com/forums/forced-in...-new-best.html
