rossman Posted July 3, 2009 Share Posted July 3, 2009 (edited) I am hoping some of you more seasoned turbo guys can help me decide on a turbine housing. I currently have a GT35R with a .63 A/R ATP "ultimate" internal waste gate setup mounted to a ported stock turbo manifold. This is going on a Rebello built 3.0L L6 with 8.5:1 forged internals, ported head and a custom cam. Details are in my project page. I recently purchased a custom made, divided t4 manifold with an external wastegate. I originally planned on buying a bolt-on t4>t3 ebay adapter, BUT....while I'm at it (been here before?), I might as well look into other options that might have performance advantages. This is where you come in . Here are the "best" options available from ATP I have come up with so far: 1) Keep my current housing and buy a block-off plate with a 3" v-band outlet. 2) Switch to a divided t3, .78 A/R turbine housing and weld or bolt on a divided t4>t3 adapter 3) Switch to a divided 1.06 A/R t4 turbine housing. Here are some considerations: 1) This will be a street and occasional track day car 2) I don't want to keep the boost threshold at a reasonable level, i.e. full boost by 4K 3) I'm not looking for the L6 HP record but I'd like a street worthy 400+ HP machine. I am open to other ideas and vendors. I only looked at ATP because that is who I purchased my turbo from and I know their housings will work with their turbos. Edited July 3, 2009 by rossman clarified text Quote Link to comment Share on other sites More sharing options...
djz Posted July 4, 2009 Share Posted July 4, 2009 I'd probably look for something in a divided T04 flange with an a/r around the 0.8 kind of range, I'd say the 1.06 housing would be a bit laggy. My car is a 3.1L with a 0.70 undivided T04 housing and it makes full boost (1.1 bar) at about 4400rpm. So with a ball bearing turbo and a divided manifold/housing you should easily be making it under 4000. Quote Link to comment Share on other sites More sharing options...
Vindicare Posted July 4, 2009 Share Posted July 4, 2009 is the t3 .8 housing not a good middle ground? that's what I just just purchase for my L24et Quote Link to comment Share on other sites More sharing options...
rossman Posted July 4, 2009 Author Share Posted July 4, 2009 is the t3 .8 housing not a good middle ground? that's what I just just purchase for my L24et It probably is a good choice. It would be nice to find a t4 .8 housing as djz suggested but I can't seem to find one online. Quote Link to comment Share on other sites More sharing options...
jeffp Posted July 5, 2009 Share Posted July 5, 2009 I have run a .7 A/R a .82 A/R and the .63 A/R turbine housing. For the street you are better off running a .63 A/R housing hands down. I was getting spool with the .70 and .82 housings at 3400-3500 rpm's. With the .63 I get spool at 3100-3200 rpm's. Dont worry to much about the smaller A/R as it will support up to 650Hp with a good 3" exhaust system installed. The big problem in most cases is the external wastegate. Now that can be a problem for a stock mnaifold, but there have been a few people who have welded a good wastegate on a stock turbo manifold. So there you have it. The divided housing in my opinion is a waste of time and effort. I would not recommend using a 1.06 A/R housing except in race applications ONLY like out on the salt flats. You go that high and your spool will be for S#it. I never even ran a 1.06 housing, totally out of my engine specifications, so if you want more then 650Hp run the bigger housing, but you will run into many more critical problems like engine cooling I can attest to that. Quote Link to comment Share on other sites More sharing options...
Supra510 Posted July 5, 2009 Share Posted July 5, 2009 Stay .63, better for your goals. I have a .69 housing on my turbo which has the compressor housing and wheel for the GT35R turbo, but is not ball bearing. I hit 398 rwhp on 18 psi with conservative timing on my 3.0 7m-gte. Quote Link to comment Share on other sites More sharing options...
rossman Posted July 5, 2009 Author Share Posted July 5, 2009 I have run a .7 A/R a .82 A/R and the .63 A/R turbine housing.For the street you are better off running a .63 A/R housing hands down. I was getting spool with the .70 and .82 housings at 3400-3500 rpm's. With the .63 I get spool at 3100-3200 rpm's. Dont worry to much about the smaller A/R as it will support up to 650Hp with a good 3" exhaust system installed. The big problem in most cases is the external wastegate. Now that can be a problem for a stock mnaifold, but there have been a few people who have welded a good wastegate on a stock turbo manifold. So there you have it. The divided housing in my opinion is a waste of time and effort. I would not recommend using a 1.06 A/R housing except in race applications ONLY like out on the salt flats. You go that high and your spool will be for S#it. I never even ran a 1.06 housing, totally out of my engine specifications, so if you want more then 650Hp run the bigger housing, but you will run into many more critical problems like engine cooling I can attest to that. Hmmm decisions, decisions. I like your advice because you are making it sound like my current setup is good. That means less money to spend. No stock manifold here, I've got a custom divided turbo header with a big a$$ wastegate. It's funny, I was planning to run an internal Ford style wastegate but I was talking with a fellow who told me how he destroyed his turbo buick due to boost spikes caused by his undersized wastegate. I agree that a 1.06 is probably way too high, but it's offered so I threw it in the mix. Quote Link to comment Share on other sites More sharing options...
zxtman Posted July 6, 2009 Share Posted July 6, 2009 I would only go with a .63 A/R if your wastegate can dump enough exhaust; otherwise, you will not be able to control boost pressure. I think a .70 A/R would be your all around best bet. Quote Link to comment Share on other sites More sharing options...
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