Rear Mount Turbo Question
Thread Starter
Racer
Joined: Jul 2011
Posts: 455
Likes: 0
From: Dalton GA
Rear Mount Turbo Question
I have seen this question asked before and still haven't found a real answer or anyone who has tried it. I am build a rear mount single turbo kit for my 98'. I am using a Garrett 71mm turbo with .96 A/R and I wondering with I should using 2.5" hot side or a 3" hot side. For the time being this stock motor will never see more than 8 pounds. I know 2.5" I can spool the turbo faster but I don't want it to be a restiction either. Let me know what you think!
Thanks
Ross
Thanks
Ross
Racer
Joined: Jan 2011
Posts: 371
Likes: 1
From: Windsor Ontario
Run 2.5 off the manifolds to a Y pipe, from the Y-pipe back to the turbo run 3”. I think a single 2.5 would cause too much backpressure.
For the cold side run a single 2.5 to the intercooler then from the intercooler to the TB 3.00”->3.5”. The 2.5 inch will support the power and also help with spool times a tad. My friend runs this setup in is F-body (370/th400) his spools instantly. Much faster than my old 370 T6 front mount setup did.
He has ran so far on his first time out a 10.80@123iirc. His back half isn’t gaining much but I think it is due to his 4000 stall convertor and the 68mm hotside on his turbo.
He runs a Turbonetics F1-68, 76mm .96a/r (basically a small frame turbo with a big wheel)
Be sure to wrap all of the hot side, and look into a turbo blanket.
I hope to start building mine this fall.
Plans so far are the same turbo as my friend but a .81a/r since I have a 6speed. I am also looking into the Borg warner S400 T4 versions. Possibly a S472 with a T4 hotside.
Goodluck and make a build thread!
Jay
For the cold side run a single 2.5 to the intercooler then from the intercooler to the TB 3.00”->3.5”. The 2.5 inch will support the power and also help with spool times a tad. My friend runs this setup in is F-body (370/th400) his spools instantly. Much faster than my old 370 T6 front mount setup did.
He has ran so far on his first time out a 10.80@123iirc. His back half isn’t gaining much but I think it is due to his 4000 stall convertor and the 68mm hotside on his turbo.
He runs a Turbonetics F1-68, 76mm .96a/r (basically a small frame turbo with a big wheel)
Be sure to wrap all of the hot side, and look into a turbo blanket.
I hope to start building mine this fall.
Plans so far are the same turbo as my friend but a .81a/r since I have a 6speed. I am also looking into the Borg warner S400 T4 versions. Possibly a S472 with a T4 hotside.
Goodluck and make a build thread!
Jay
Advanced
Joined: Feb 2012
Posts: 75
Likes: 0
From: Palm Harbor Florida
Run 2.5 off the manifolds to a Y pipe, from the Y-pipe back to the turbo run 3”. I think a single 2.5 would cause too much backpressure.
For the cold side run a single 2.5 to the intercooler then from the intercooler to the TB 3.00”->3.5”. The 2.5 inch will support the power and also help with spool times a tad. My friend runs this setup in is F-body (370/th400) his spools instantly. Much faster than my old 370 T6 front mount setup did.
He has ran so far on his first time out a 10.80@123iirc. His back half isn’t gaining much but I think it is due to his 4000 stall convertor and the 68mm hotside on his turbo.
He runs a Turbonetics F1-68, 76mm .96a/r (basically a small frame turbo with a big wheel)
Be sure to wrap all of the hot side, and look into a turbo blanket.
I hope to start building mine this fall.
Plans so far are the same turbo as my friend but a .81a/r since I have a 6speed. I am also looking into the Borg warner S400 T4 versions. Possibly a S472 with a T4 hotside.
Goodluck and make a build thread!
Jay
For the cold side run a single 2.5 to the intercooler then from the intercooler to the TB 3.00”->3.5”. The 2.5 inch will support the power and also help with spool times a tad. My friend runs this setup in is F-body (370/th400) his spools instantly. Much faster than my old 370 T6 front mount setup did.
He has ran so far on his first time out a 10.80@123iirc. His back half isn’t gaining much but I think it is due to his 4000 stall convertor and the 68mm hotside on his turbo.
He runs a Turbonetics F1-68, 76mm .96a/r (basically a small frame turbo with a big wheel)
Be sure to wrap all of the hot side, and look into a turbo blanket.
I hope to start building mine this fall.
Plans so far are the same turbo as my friend but a .81a/r since I have a 6speed. I am also looking into the Borg warner S400 T4 versions. Possibly a S472 with a T4 hotside.
Goodluck and make a build thread!
Jay
I am assembling my rear mount within the next month. I have all the parts except piping. 2.5" to 3" Y on hotside. 2.5" cold side back to the front. Follow what he has above and you'll be set. I'm also doing a T76 with .81AR since I'm a 6-speed as well.
Burning Brakes
Joined: Sep 2011
Posts: 764
Likes: 19
From: odessa FL
Agree with wrapping the exhaust, but don't think the turbo blanket will help any in terms of power especially in a rear mount and may even be detrimental to durability.
Underhood, it does help with the heat in the engine compartment.
Underhood, it does help with the heat in the engine compartment.
Advanced
Joined: Feb 2012
Posts: 75
Likes: 0
From: Palm Harbor Florida
.81 exhaust side is what I am using and what the others are talking about. The exhaust side will determine spool speed because the smaller the turbine the less pressure it will take to spin it compared to a larger turbine. Since the turbo is in the rear, you want to reduce spool time as much as possible without going too small and running out efficiency in high rpm. A lot of guys have found the .81 to be the perfect solution. I will know soon!!
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Advanced
Joined: Feb 2012
Posts: 75
Likes: 0
From: Palm Harbor Florida
Mild steel will rust. I'm going with aluminized stell bc it won't rust but stainless would be preferred if it was in my budget. Aluminum works on front mounts but is too brittle to be exposed as much as it is on a rear mount IMO. Stainless or aluminized steel is the way to go
