Small turbo limits?
10-05-2009, 06:23 PM
#1
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Small turbo limits? My car is #3200, stock LS1, th400 w/tb, 3.50 gear, 30in. tire, an unknown turbo (maybe an ITS GT66) and its Air to Air intercooled. I ran a 10.78 @ 125mph with a 1.52 60ft. on 7 psi. Only 20deg. of timing and left at 3300rpm. The car only made 25mph from 1/8 to 1/4. I think that it should make more speed on the top end. Could I have reached the limit on the turbo? From 11.80 on down to the tens the car ran 125mph every time. The 60ft times got better and the et's improved but, no mph gain. I'm new to owning a turbo car but, don't these cars run the finish line really good? The turbo is small to begin with, I know. If I changed the .81 a/r housing to a .96 will it run better? Seems like from 3/4 throttle to 100% there is no change in power. The tune is pretty good, 11.5-12.0 afr, about 1450 egt, I'm using bigstuff3 and an exile boost controller. The car was built for a small cube motor "5.3" but, for now it has the LS1 because I had it to use. It runs the first half really good for having a 3.50 gear in my opinion but, its not pulling like I expected. Any ideas?
10-05-2009, 06:57 PM
#6
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4 inch down pipe into a custom sheet metal pipe. Its about a 4ft run of 4 inch and it merges into the sheet metal by the starter. It exits like a NASCAR out the side under the door. No muffler, loud and it is burning my new paint on the rocker. LOL I could plasma a hole in the inner fender and dump it behind the tire if I need to.
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10-05-2009, 08:03 PM
#8
If it is around a 66mm inducer like you think that should easily still support more than 7 psi on stock cubes and longblock
It should be easy to see or read on the turbine housing what AR it is, should check that out aswell
10-05-2009, 08:18 PM
#9
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I measured the cold side: 2.595-just under 66mm and 3.498-just under 88mm. Its a 4in inlet and a 2 1/2 outlet. Couldn't get the hot side off to measure but, its a 3in outlet, .81 A/R, t4 flange and it looks like there is a Q and some other numbers cast on the side. Thanks for the help. This is supposed to be a good turbo, someone purchased it for a ford 302 build and I picked it up three years ago when I started my build.
10-05-2009, 08:31 PM
#10
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I think the cold side will do the job. The hot side seems to be the issue. .81 a/r is tight in my opinion. I just put this setup together as a learning combo and it ran way better than expected. Now my goal is to get as much as I can out of it. It would be nice to come out next season and run low 10's. I'm almost there, not even using the meth kit yet.
