BoostedLilRe
Well-Known Member
I have twin 76 Chinese GT45’s. I’m thinking of going to twin 67’s with .81ar for quicker spool. Any thoughts or advice on this. 76’s spool slow for me.
Turbo change
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BoostedLilRe
Well-Known Member
I have a build thread on here. Twin turbo Lilred express. 408 stroker SCU 850 blow thru Hughes super heads. M1 intake. 3.73 Ford 9 inch 727auto. 33 inch tall tire.
TT5.9mag
Two atmospheres are better than one
Ok I found your build thread and read through it. Your truck is super bad ***. But there was zero information about the engine build. So I’ll ask a few questions. Fill me in and I can run some numbers on turbo sizing.
1. What fuel?
2. Compression ratio?
3. Power goal?
4. Max RPM?
5. Weight of truck?
6. Cam specs?
7. How much boost?
So far I know 408 cu/in, single plane, blow through, no intercooler.
I use Garrett’s turbo sizing form as a guideline and it been pretty close for general sizing.
1. What fuel?
2. Compression ratio?
3. Power goal?
4. Max RPM?
5. Weight of truck?
6. Cam specs?
7. How much boost?
So far I know 408 cu/in, single plane, blow through, no intercooler.
I use Garrett’s turbo sizing form as a guideline and it been pretty close for general sizing.
BoostedLilRe
Well-Known Member
Pump gas 93. 9/1 comp. 800hp. 6200max rpm. 3150lbs. 544/280 544/290 roller. Have made 9.9lbs. I am ditching the blow thru next week and going with Holley 1250 super sniper efi.
Are you sure they’re 76mm turbos? They look like the standard Chinese GT45’s which are a 69mm. I’d be impressed/confused if you’re spooling twin 76’s at all in your relatively limited rpm range.
What cylinder heads?
A lot of the LS guys in your same displacement range have found twin GT35’s to provide plenty of power and fast spool. They would certainly support your power goals.
BoostedLilRe
Well-Known Member
BoostedLilRe
Well-Known Member
I think my actual issue is the turbine. It measures 1.04. So I’m thinking of switching to 67’s with an .81ar turbine.
I missed the Hughes super heads.
Turbine housings would make some difference, but still way too much turbo in my opinion. Unless you’re shouting for low 8’s.
Gt3582’s are what I’d run. They would likely spool close to 2000rpm sooner and capable of more power than your block can handle.
Turbine housings would make some difference, but still way too much turbo in my opinion. Unless you’re shouting for low 8’s.
Gt3582’s are what I’d run. They would likely spool close to 2000rpm sooner and capable of more power than your block can handle.
BoostedLilRe
Well-Known Member
I’d like to try and stay in the T-4 family so I don’t have to re pipe my hot side.
TT5.9mag
Two atmospheres are better than one
I had assumed that was a driving factor. They do make a t4 version.
The 3076 compressor flows plenty, but the exhaust side is too small for a 400” motor. Would probably fall on its face around 5k rpm.
BoostedLilRe
Well-Known Member
The 3582 looks to offer several setups also. Which combo would you go with.
So if I go with the 3582 which combo. Comp/turbine? Try and stay near a 62/ 81
TT5.9mag
Two atmospheres are better than one
All of these are too small for a 400” motor. But when you run 2 of em they’re about perfect for 200”. The 3071 and 3076 have the same turbine wheel 60-55, the compressor being 5mm larger on the 3076, 53-71 vs 57-76. The 3582 is close but a little larger on both wheels, 68-62 turbine and 61-88 compressor. The decision to stay with a T4 flange will likely push you, (@BoostedLilRe) towards a little larger frame turbo. You can get the turbine for the 3582 in a couple A/Rs I’d lean towards the smaller ones. Like .82 for a street car.
I would agree on the .82 ar t4 turbine housing for that Gt35 configuration…if you can find it. I still think the 30series is too small even if you went t3(I ran a 3076 @ 150ci). They do make t4->t3 adapters.
At what rpm are you seeing full boost now?
Im very curious to see how the super sniper does with your setup. I’ve been tuning my buddies 454/F1 combo and it’s been a real pleasure vs carb tuning. I hope you plan to take advantage of timing control.
BoostedLilRe
Well-Known Member
My timing is run by MSD 6530. Don’t plan on changing that. I have boost maps and two step set up thru it. I’m leaning towards the gt35 but not in a major rush so going to do more research. I do appreciate everyone’s time and energy helping with this.
Have you seen this reverse mirror option from VSRacing? I’d love to do a twin turbo just to use these. I “think” the specs are close to a 3582. VSR Gen2 67/62 CAST Journal Reverse Mirror or Normal Rotation Turbo – VSRacing
BoostedLilRe
Well-Known Member
Yes I have seen that. Just don’t know if 67 is to big with twins.
True. They do have a 62/62 option with reverse which is probably closer to the 3582 but a bit more spendy. VSR Next Gen 62/62 DBB Billet – VSRacing
I would absolutely go this 6262 route if it’s in your budget.
I’m going 6530 for timing on my carbureted build, but no way would I choose it over the super sniper.
BoostedLilRe
Well-Known Member
The vs6262 has a t4 open option with an .81ar. $599. I think I’m gonna go that direction.
TT5.9mag
Two atmospheres are better than one
You’re correct. My bad not sure how I missed it.
You won’t be disappointed. I have two of their nex gen 7875s for my 500” BBC in my boat. I completely disassembled both of them scrutinizing every critical measurement and they were spot on. Super nice turbos for the price.
BoostedLilRe
Well-Known Member
Pretty sure my mind is made up. Should spool much faster than what I have now. And a better power band.
I missed that my first time too, but Subcom’s second post got me where I needed.
Is there a build thread for that boat?? I’d love to learn more about it!
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