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Smallest twin for 5.7 ls1 swap

 
Old 07-26-2017, 11:06 AM
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Default Smallest twin for 5.7 ls1 swap

Hello,
Been reading alot.
Just thought i would ask to get ideas.
Space is tight, Ac cobra ls1.
Asking what is smallest set of budget turbos i could use.
I would have to custom mount hotside mid engine.
Goals are 550rwhp ish but would never exceed 650 to 700, engine currently stock except for 224r cam and mildly ported 241's.
Diff is XJS dana 3.54 and tyres currently 255 40 17, t56 gearbox. Weight roughly 1100kg.
Would want quickish spool time.
I could custom fab and weld all own hot/cold side and got wideband to mostly self tune with my efilive cos3 op system.
No room for single up front due to cross member.
On3 turbos 61mm?
Got side pipes so would be a side exit exhaust.
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Old 07-26-2017, 01:08 PM
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Waste of effort and money to turbo an LS1 with that power goal.
Build a stronger N/A version of LS with aluminum block and heads, it will be faster in all aspects.

If you are dead set on twin turbo, look into the Comp brand oil-less turbos. Only water cooled lets them work at any angle and direction including straight vertical. Still overkill as the decent sized 62mm still capable of 600hp each (1,200hp total with twins).
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Old 07-26-2017, 02:07 PM
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Thanks for reply, forgot to add though i am in uk so heads etc to get here works out quite expensive.
For a non GM clutch was quoted around $600 extra to get it delivered and through customs...
Have looked at heads though, wouldnt get me to 550rwhp with my block though and dont really want to change this. But did look at prc 2.5 5.3l heads to death and Mamo heads. Exchange rate for here is crap since i looked so thats why havnt pursued those routes yet. Even looked at D1sc but might not fit
Mine is 2003 ls6 blick with ls1 heads atm.
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Old 07-26-2017, 02:19 PM
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Originally Posted by imma_stocker View Post
Waste of effort and money to turbo an LS1 with that power goal.
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Old 07-26-2017, 07:10 PM
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GT35 based turbos.
You could even get away with some super small ebay 50-56mm turbos as long as you ran external gates.
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Old 07-26-2017, 09:31 PM
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I'd bet this would do 550ish. About as small and cheap as possible... I'm buying one to put on my desk as work for that price...

http://www.ebay.com/itm/T3-T4-T04E-T...lZCYUM&vxp=mtr

The Gt35 mentioned above is a better match with room to grow. Proven to make more than your goal and they look fancy for a $160 turbo.

http://www.ebay.com/itm/T3-flange-GT...pXB3nf&vxp=mtr

Last edited by Forcefed86; 07-26-2017 at 09:37 PM.
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Old 07-27-2017, 04:34 AM
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Hi,
Thanks alot all.
Is this the same in uk http://www.ebay.co.uk/itm/Turbo-T3-G...kAAOSw241YhFG~ ??
Though says 0.63 0.7.....
Also these are water cooled, so are they more prone to failure at this price? Didnt consider water cooled, will have to look at how to do that.
Lastly anyone got any physical dimensions end to end and max diameter?
Thanks for all this though.
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Old 07-27-2017, 06:38 AM
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Yes, that's basically a standard 6262 GT35 from ebay. If you look hard enough, you can probably find one with a V-band outlet and T4 flange if you want, but its not necessary.

Water cooling is typically just an option. It means that the center section has a port that you can pass your coolant through to keep temperatures reasonable. Its far more common on OEM stuff than aftermarket.
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Old 07-27-2017, 08:35 AM
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Originally Posted by Forcefed86 View Post
I'd bet this would do 550ish. About as small and cheap as possible... I'm buying one to put on my desk as work for that price...

http://www.ebay.com/itm/T3-T4-T04E-T...lZCYUM&vxp=mtr
That's the same 5056 turbo I've used a dozen times now, although I always opt for the v-band outlet versions from DNA since they come with the downpipe v-band and clamp.

A pair of those on a stock 4.8 with the trick flow 216/220 made 600 wheel through a T56 with internal gates. We had to swap to externals to be able to get boost below 17 PSI when we swapped to a 5.3.

4 of those with internal gates and anti-surge housing currently reside on the Chupacabra.
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Old 07-27-2017, 11:50 AM
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Originally Posted by Hank Peabody View Post
Good point!!
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Old 07-27-2017, 12:05 PM
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I think GT35s would be way overkill for 550-600whp. The old C5 twin turbo kits from the 90s/early 2000s used GT28s and were capable of those power levels. The physical size between a GT28 and GT35 is considerable.
Attached Thumbnails Smallest twin for 5.7 ls1 swap-gt28gt352.jpg  
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Old 07-27-2017, 02:42 PM
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Hi,
I could go even smaller then eh?
Anyone for any dimensions for either of these?
The water cooling i guess i just plumb from the both from the heater circuit...?
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Old 07-28-2017, 06:34 AM
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Maybe another option worth looking into is the mitsubishi stuff like the 16G. Those turbos are pretty small and good for around 400hp each. Dunno if the internal gate would work on a biggish V8 tho?
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Old 07-28-2017, 06:57 AM
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The smaller 50mm turbos that ForceFed86 linked work fine, and they're $100-125 depending on where you look. I've used a ton of them. Do NOT get the internal gate versions. The internal gates on them are 21mm and internal gates are typically a bad design compared to externals, which does them even less favors. They would boost spike to 17 lbs on a stock 4.8.

The comparison picture between a GT28 and GT35 isn't quite accurate with the ebay stuff. The ebay GT35s are usually much smaller than the Garrett stuff.
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Old 07-28-2017, 07:57 AM
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Did you ever try hogging out the internal gates? I like the idea of the internal gate for packaging and 17lbs isn’t horrible… Esp if the ports for the WG are tiny and can be hogged out like on the old RX7 stuff.
Attached Thumbnails Smallest twin for 5.7 ls1 swap-internalport1.jpg  
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Old 07-28-2017, 08:11 AM
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17 PSI doesn't sound bad until you put it on a 5.3 and it boosts 20 lbs or a 5.7 and boost won't go below 21 lbs. When the 4.8 let go, a 5.3 was swapped in. It was hitting the ~17.5 PSI boost cut we had on the 4.8 by 5000 RPM.

Opening up the gates is a possibility. It won't be as easy as using a step bit to open it up though, because the opening is way off center behind the gate flap. You could safely open it up to ~28mm as long as it doesn't look like a total hack job so it will still seal.
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Old 07-28-2017, 08:18 AM
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Gotcha, thanks.

Since you’ve laid claim to the quad setup already, I was thinking of a triple setup on a log. Since they will all be on the same log dividing the flow across 3 internal gates, it should help. Dunno though, still planning at this point. Should look cool poking out of a grill if nothing else!
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Old 07-28-2017, 08:56 AM
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I debated a triple setup with a 6.0. Use a large single dead center up front with a bumper hole cut out. 2 smaller twins on the hotside close to the turbo about where wastegates would go. I sat for a while and the math just didn't pan out. as far as making sure that middle turbo gets enough flow. The plus side was an excellent backpressure ratio on the large turbo.
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Old 07-28-2017, 09:18 AM
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I’m assuming with 3 like turbos drive pressure would be split equally between all 3 on the log.

Can’t decide between running a bank to each side of the log with internal gates… Or running both banks to one side of the log with a WG on the other end and no internal gates.
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Old 07-28-2017, 09:35 AM
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Yeah it wasn't that the math just didn't work, I just didn't feel like going through the effort of doing it all haha. With what I wanted with a large single in the middle, I was trying to figure out at what point the exhaust would take the path of least resistance.

Using 3 identical turbos takes all of that out of the equation.
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