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So I'm just kicking around the idea of doing a twin turbo setup, and I'm in the research phase. I've got most of my parts sorted and matched. I'd like to do 2 Borg Warner S300SX3 66mm turbos. I need to figure out intercoolers now. I'd like to not spend a sh*t ton on intercooler piping and whatnot, I'm on a budget of about 2k for the entire turbo setup. I'm wondering if it would be better to run a single intercooler or dual intercoolers? I looked at some dual 3" inlet to single 4" outlet intercoolers but they're like 600$. Maybe I could buy a 3" in and out intercooler and cut and fab a top exit for a single out and use the 3" piping for the inlets? Thanks!
Edit: forgot to mention the setup for the motor. I'm building it right now. It's an '11 L96 iron block with a stock crank, TSP H-Beam Rods, and Wiseco PTS523AS pistons. I have the 823 casting ls3 style heads and plan on doing a BTR trunion upgrade. I'm waiting to hear back on a cam from TSP or BTR, but I think any of their turbo cams will be good. Planned on doing a TSP stage 3 turbo cam. Some miscellaneous BS that I have to spew in no particular order: 7.400 pushrods, melling oil pump, arp headstuds, ls9 headgaskets, keep my stock lifters and trays (they look pretty good), I plan on keeping a stock intake I don't really see going up from the 87mm intake being a benefit, and some other various things that I can't think of right now but they're somewhere floating around up there. Woohoo!
Last edited by happycaptain; Apr 15, 2020 at 01:43 AM.
I had seen another rev9 intercooler that would have been nearly perfect, but I didn't know if it would be enough surface to cool down what those turbos would be spitting out. The other issue that I had was that I would like to do all 3" piping and not have to step down to a 2.5" intake on an intercooler and cause a restriction. This was promising, because it would make my life easy but again, 2.5" intakes on that sucker.
Last edited by happycaptain; Apr 15, 2020 at 07:02 AM.
Reason: grammar
On my twins (GT35 clones) I have this intercooler
When logging with my HPTuners, the IAT's at 23 psi were 59 degrees. Admittedly, this was evaluated in the yesterday here in upstate NY where the temps are still in the 40's and 50's and I don't stay in boost very long because I'm having trouble keeping the rear of the car from passing the front of it. This intercooler has dual 2.5" in and dual 2.5" out. It fits in the same confines as my prior 3.0" in/out intercooler I had with the PT7675.
I'm trying to remember what I paid for it but it was inexpensive for sure.
I have twin gt35s and i run 2 side mounts. No real data for IATs cause haven’t been driving hard due to no tune and no exhaust yet. However they work great of the car and are HUGE. Car comes factory TT designed for the SMICs too though.
these are the biggest aftermarket ones for the 300zx. There are 3 name brands that all use same core and 2.5” ends so I just got the cheapest of the 3. $450 for the pair. They are used on 700hp + nissans. However I don’t think posts ever come up about IATs for the v6 motors. Seems v8 guys pay way more attention to the details lol. The average 600hp setup used gt28s though. Gt3071s are the biggest can fit on the motors.
Back when I first put a turbo (Turbonetics TC76, later upgraded to a billet wheel PT7675) on my then LT1 equipped Z28, I'd read that an intercooler was 'beneficial' but the implication was that it wasn't absolutely necessary. I put on a $200 OBX single 3.0" in/out intercooler on the car and didn't think about it anymore. That was 2008. Fast forward to 2014 and, while the LT1 engine was still running great, I followed the herd and bought/built a 5.3. Once again, reading up and talking with a few import guys, it seemed that E85 was a good thing to fuel the new setup. I pulled and sold the LT1 and installed the 5.3, utilizing the prior Turbo PT76 and intercooler. It ran great and I was happy, but then read "If you run E85, you don't need an intercooler due to the properties of E85". I had several scans of past runs with the E85 fueled 5.3 so I noted the peak IAT during a pass was 125 degrees. I removed the intercooler tubing and routed the compressor outlet directly to the Throttle Body, then hooked up my HPTuners scanner and went and made a full pass. When I got back to the pits, I read the scan. Good God... 230 degrees. So, I went back to the shop and hooked up the intercooler again. The OBX is a cheap intercooler but it did the job for my application.
When the weather gets to be warmer and I can make a full pass (Still trying to attenuate the wastegate spring pressure. Shoots up past 20 psi in heartbeat with 67% throttle), I'll remeasure the IAT's. This intercooler I'm using cost $99 or so. I didn't expect it to perform a stellar job but so far, it's keeping the temps below 80 degrees no matter what PSI I run.
Back when I first put a turbo (Turbonetics TC76, later upgraded to a billet wheel PT7675) on my then LT1 equipped Z28, I'd read that an intercooler was 'beneficial' but the implication was that it wasn't absolutely necessary. I put on a $200 OBX single 3.0" in/out intercooler on the car and didn't think about it anymore. That was 2008. Fast forward to 2014 and, while the LT1 engine was still running great, I followed the herd and bought/built a 5.3. Once again, reading up and talking with a few import guys, it seemed that E85 was a good thing to fuel the new setup. I pulled and sold the LT1 and installed the 5.3, utilizing the prior Turbo PT76 and intercooler. It ran great and I was happy, but then read "If you run E85, you don't need an intercooler due to the properties of E85". I had several scans of past runs with the E85 fueled 5.3 so I noted the peak IAT during a pass was 125 degrees. I removed the intercooler tubing and routed the compressor outlet directly to the Throttle Body, then hooked up my HPTuners scanner and went and made a full pass. When I got back to the pits, I read the scan. Good God... 230 degrees. So, I went back to the shop and hooked up the intercooler again. The OBX is a cheap intercooler but it did the job for my application.
When the weather gets to be warmer and I can make a full pass (Still trying to attenuate the wastegate spring pressure. Shoots up past 20 psi in heartbeat with 67% throttle), I'll remeasure the IAT's. This intercooler I'm using cost $99 or so. I didn't expect it to perform a stellar job but so far, it's keeping the temps below 80 degrees no matter what PSI I run.
so that intercooler you have with dual outlets and inlets, while better than none looks identical to the ones we run on Nissans from eBay over the SMICs stock size. However the best tuner from our z community wrote back and forth with me in emails awhile ago and made it clear the stock intercooler actually was more effective than those eBay ones.
“””The whole system has to work together to move air efficiently, your correct that your front mount is a significant restriction, it actually flows less than stock intercoolers due to the long core and small charge face. Between the intercooler and 2 inch intercooler pipes, you have about a 4 PSI pressure drop from turbo outlet to throttle body.””””
so the 2” intercooler piping is because stock turbos outlets are 2”. Here are some pics he sent me of he side mounts being more efficient.
My side mounts are alittle bigger than those ashpec ones in pic.
Also this as pertains to turbos breathing
”””On stock turbos, with full 2.5" turbo back exhaust, larger intercoolers, single pop, we use to get about 330 Rear wheel HP at 14 to 15 PSI on 91 octane pump fuel.....
Now with stock turbos, 3 inch exhaust, 2.5" intercooler pipes, 2.5" massive intercoolers, dual pops and MSP manifolds at the same 14 to 15 PSI boost, we get about 415 Rear wheel HP on 91 octane pump fuel. And over 500 at the tires on E85”””
Quite the change in output! On mine, since it's primarily a street car (no cage. I've already been scolded at the track after the first 10.5 it ran. They only let me run 1/8th miles now, and that was with the single PT76) I'm just looking to keep the IAT's down. Right now on the streets , in the limited driving(only been driving the last 2 weeks) I've had with the new twin GT35's, It already feels quicker than before. I should get it dyno'd. Usually, I just go to the track and let the MPH tell me what she's putting down, but with this Corona Virus insanity going on, the local track is closed till further notice.
So I'm just kicking around the idea of doing a twin turbo setup, and I'm in the research phase. I've got most of my parts sorted and matched. I'd like to do 2 Borg Warner S300SX3 66mm turbos. I need to figure out intercoolers now. I'd like to not spend a sh*t ton on intercooler piping and whatnot, I'm on a budget of about 2k for the entire turbo setup. I'm wondering if it would be better to run a single intercooler or dual intercoolers? I looked at some dual 3" inlet to single 4" outlet intercoolers but they're like 600$. Maybe I could buy a 3" in and out intercooler and cut and fab a top exit for a single out and use the 3" piping for the inlets? Thanks!
Edit: forgot to mention the setup for the motor. I'm building it right now. It's an '11 L96 iron block with a stock crank, TSP H-Beam Rods, and Wiseco PTS523AS pistons. I have the 823 casting ls3 style heads and plan on doing a BTR trunion upgrade. I'm waiting to hear back on a cam from TSP or BTR, but I think any of their turbo cams will be good. Planned on doing a TSP stage 3 turbo cam. Some miscellaneous BS that I have to spew in no particular order: 7.400 pushrods, melling oil pump, arp headstuds, ls9 headgaskets, keep my stock lifters and trays (they look pretty good), I plan on keeping a stock intake I don't really see going up from the 87mm intake being a benefit, and some other various things that I can't think of right now but they're somewhere floating around up there. Woohoo!
You can get these cheap on ebay… 3.5 inlet/outlet, rated at 1200hp each, even without water IAT's aren't bad at all.
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Single Versus Dual Intercoolers for Twin Setup? 
