Twins or big single? Exhaust constraints
Twins or big single? Exhaust constraints I'm debating on a big single or twins. Unfortunately my lsx swap is very tight. The only way to run my exhaust outback is through a 3" pipe. Besides the obvious power loss is there anything I should consider while running twins and such tight exhuast parameters? Would it be THAT much better to run a single vs. Twins under these conditions? I'm working very hard to be able to run dual 3" pipes outback but worst case senario is looking like both 66's dumping into a single 3" pipe.
Turbos will be BW s366 .91 or s475 1.0
Turbos will be BW s366 .91 or s475 1.0
I'd go single s475 over twin s366 turbos if its through a single 3". Even if you run dual 2.5" downpipes it'll still make a ton of power. I ran a twin kit with dual 2.5" downpipes and in a truck weighing 4800lbs, 6.0 on 16psi and it ran a train on a 129mph cobra on the highway. Just don't get crazy with the cam and it'll move out.
Launching!
Joined: Jan 2012
Posts: 216
Likes: 1
From: Davisburg, MI
Have you looked at ovaling the pipes as a means to get a 3.5" out?
Twin turbos are cool. A big single is getting twice as much exhaust with less inertia and friction to overcome. I'd love to see a comparison where both were optomized for the same engine. Plenty of people setting records with big singles.
Twin turbos are cool. A big single is getting twice as much exhaust with less inertia and friction to overcome. I'd love to see a comparison where both were optomized for the same engine. Plenty of people setting records with big singles.
The goal is 800 for now but like everything else I own it doesn't last long. If it's possible to run dual 3" or 2.5 out back ill probably go with twins just for the cool factor (I've always wanted to own a twin turbo car) I like the simplicity of a single but the future need to bump up power is always lingering.
Any big single can keep up with a set of twins...that's why a bigger single is used anyway. Of course if you run twin 114mm turbos then you'd be hard pressed to find a single to run with those, but that's outside the scope. With twins the big difference is power under the curve. If you just want to hit a peak number though, single is enough. That said...if its one 3" downpipe vs dual 2.5s or 3s...I'd go twin turbo. lol
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TECH Apprentice
Joined: Apr 2012
Posts: 333
Likes: 4
From: New Zealand
As above, hp is about cfm and the engine don't care if it comes from 1 or 4 turbos. Twins will spool quicker and have more down lower, but having said that my old single LS1 could boost from a dig by braking and loading the converter, so don't sweat it.
Here's a thought for tight space: do a single rear mount, then you can run a conventional exhaust manifold 2 into 1 big bore exhaust out. Course you then need to figure how to plumb the intake back up front (but it could be oval and only 2-2.5"high) as it could run all the way to the front and not have to weave through the engine bay (if you have clearance).
Here's a thought for tight space: do a single rear mount, then you can run a conventional exhaust manifold 2 into 1 big bore exhaust out. Course you then need to figure how to plumb the intake back up front (but it could be oval and only 2-2.5"high) as it could run all the way to the front and not have to weave through the engine bay (if you have clearance).
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I agree, twin tial 44 or jgs would work well, but it will depend a lot on the size of the motor. A 5.3 could probably get away with 38mm where a 427 would need 44 or larger depending on the amount of boost you plan to run. The smaller the turbo and the larger the engine with lower boost, the larger the wastegate needs to be if that makes sense.
Makes perfect sense. I've been chatting with a few guys about what turbo to run if I go twin and I'm getting a lot of small turbo feedback. S262 etc. to reiterate my goals are 800 on pump gas with the ability to jump up to 1000k. I'm being told that twin s366 is a little overkill for my lq4. The goal is street ability but I want this thing to pull like a fighter jet on the freeway. This car will be mainly a freeway queen, I'm going after those high HP GTR's
Twin s256 would spool lightning quick and make around 800. Probably close in on 1000 as there are 4 bangers making over 500. Are you doing a 5.3 or 6.0? I know you said lq4, but just making sure.
I have the 6.0. One major issue I have with my build is extreme space constraints. Whatever turbo I go with it will have to be smallish but be able to produce big numbers in a twin configuration. Also once I pick a turbo and build a kit around it, that it's. There will be no room for larger turbos. I'm not even 100% sure I will have room to route the exhaust for one of the turbos. I'm pretty crafty though!
If you can fit a single T6 or T4, you could do the s480 with the 92 or 96mm turbine and have 1000 whp capability or more if you went billet. Of you are set on twins, see if you can fit twin s360 or s362 turbos.
