This is a weird one, but need your feedback (Long)

[Boostage]

Ok here goes.

I am in the middle of doing a 1jz swap in an s14. however Im not going a custom Twin setup. that uses t2 manifolds. This motor belongs to a buddy of mine but my setup is Identical..
http://i188.photobucket.com/albums/z191/drewgoperformance/Twin%20Manifolds/SSPX0092.jpg

http://i188.photobucket.com/albums/z191/drewgoperformance/Twin%20Manifolds/SSPX0090.jpg

Those are stock rb26 Twins with the ceramic exhaust wheels (gt2556r)while they offer the sick response I would like to have, they definitely dont flow well past 350hp, or well enough for high rpm's

I know this based on a similar setup from a supra owner who I have had many conversations with. here is his setup..

http://www.bicperformance.com/pics/1jzengine%28Medium%29.JPG
http://i12.photobucket.com/albums/a249/Afrodziac/IM00024720Medium.jpg

^^^ This is his dyno, not only does power fall fast, As you can see tq starts to fall at 5k and hp starts to fall at 6500.and he got alot of surge when cruising. it was bad enough that he got rid of the whole setup.These were gt28r's that were slightly bigger than my RB twins, so for sure I need to get differnt turbos. Now I figure a 2860rs with .86 rears would probably hold power longer and not surge down low. but I am thinking of something more radical and thats where I need your feedback. I am thinking of getting..
http://i1.ebayimg.com/07/i/000/c9/fa/2854_1.JPG
http://i23.ebayimg.com/02/i/000/c9/fa/28ff_1.JPG

t25 to t3 adaptors I want to get these so I can run a pair of t3 super 60's. problem is I dont know if I would lose all low end response even with .48 exhaust housings, I just dont know how much bigger a t3 is over a t2. I would imagine a t2 .86 is still smaller than a .48 t3, but I could be wrong.

Would I lose the fast spool if I try this?

[pinkarrowsnow]

If your that concerned about lag why not just run a big single and have a little shot of nitrous. Cant normal BPU supras hit like 400 with stock twins. Lag is fun cause everyone things the car is slow and then it just hits like crazy haha.

[Boostage]

The car isnt intended for drag racing or I wouldn't even go for twins. its going in a road race car, I need great exiting response and mid range TQ. Plus I already have my setup. I know 2860rs's would work I just need to know if t3 super 60's would also work, as they are much more readily available, cheaper. and easily rebuildable.

[pinkarrowsnow]

The car isnt intended for drag racing or I wouldn't even go for twins. its going in a road race car, I need great exiting response and mid range TQ. Plus I already have my setup. I know 2860rs's would work I just need to know if t3 super 60's would also work, as they are much more readily available, cheaper. and easily rebuildable.


Ok road racing now it makes complete sense for that route.

[Monooxide]

You wont get very good response from T3 Super 60s...

Why a 1JZ if you're wanting response? A 1JZ will put more weight over the front of the subframe as well as more weight all together. That 1JZ you showed on the dyno is not response oriented in the least bit.

[Boostage]

That 1jz is indeed responsive, that powerband is on par with stock twins. except stock twins would make only 200 ft lbs @ 3k instead of the 250 ft lbs this one does. there is no lag on that setup at all.

[Monooxide]

That 1jz is indeed responsive, that powerband is on par with stock twins. except stock twins would make only 200 ft lbs @ 3k instead of the 250 ft lbs this one does. there is no lag on that setup at all.

That dyno chart is showing full boost/peak torque at like 5000+ RPM that is not responsive.

I guess I should ask the WHP you're looking for as some things arent achievable with certain goals in mind. Also, what are you going to rev to?

[Boostage]

That dyno chart is showing full boost/peak torque at like 5000+ RPM that is not responsive.

I guess I should ask the WHP you're looking for as some things arent achievable with certain goals in mind. Also, what are you going to rev to?
Again that 1jz is more responsive than the stockers Im very curious as to what you consider responsive. for any straight 6 of similar displacement. this is a stock 1jz dyno
http://i5.photobucket.com/albums/y188/phjeerable/1jz/stock-dyno2.jpg

Peak TQ [email protected] 4k, vs 5k on the gt28r's but from every rpm lower than 4k the gt28r's make a bit more power. they make like 190 foot lbs by 2200. vs about 80 ft lbs for the stockers. I dont know if you ever been in a stock 1jz but there is no noticeable lag. but to answer the second question Im going to go as high as 8800-9k rpms.

[Monooxide]

I personally think you should go with a staggered style setup, smaller primary and slightly larger secondary turbo.

Primary - S15 T28 or 2860
Second. - 2871 or 76?

Maybe just run two 2860s and stage the exhaust housings? One .64 and one .86? I haven't put a lot of thought into this kind of setup as I don't have that kind of displacement to play around with.

I know the RB26 and Z32 guys love the HKS GT2530s and Garrett GT2860s and HKS GT-SS's(discont.).

I dont mean to come off as I am bashing what you're doing, just 5000 RPM full boost isnt what I am used too.

[Monooxide]

Peak TQ [email protected] 4k, vs 5k on the gt28r's but from every rpm lower than 4k the gt28r's make a bit more power. I dont know if you ever been in a stock 1jz but there is no noticeable lag. but to answer the second question Im going to go as high as 8800-9k rpms.

Ok, now knowing that you're going that high RPM wise changes the whole ball game as 2000 RPM of useable powerband is not broad.

If I were you I would sit down and find out what compressor map will flow the lb./min that you would need to keep from "over" flowing the turbos. I would go as small as you can and then add 4-5 lb/min. and choose that turbo because at 9000 RPM you're not going to need a lot of boost or a big turbo to make power.

RPM is your friend. RPM is where power is made. RPM is where broad powerbands live.

EDIT: BTW that second graph is way more respectable. Maybe on the first one he started the WOT later?

[Boostage]

I personally think you should go with a staggered style setup, smaller primary and slightly larger secondary turbo.

Primary - S15 T28 or 2860
Second. - 2871 or 76?

Maybe just run two 2860s and stage the exhaust housings? One .64 and one .86? I haven't put a lot of thought into this kind of setup as I don't have that kind of displacement to play around with.

I know the RB26 and Z32 guys love the HKS GT2530s and Garrett GT2860s and HKS GT-SS's(discont.).

I dont mean to come off as I am bashing what you're doing, just 5000 RPM full boost isnt what I am used too.This is impossible. you cant run parallel turbos of different size, not only would boost control be impossible, but the bigger would make the smaller turbo surge. what you are thinking is compound turbocharging, which isnt what I want to do.

I did calculate the flow requirements. I need 45-50 lbs a minute flow, which the super 60 and the 2860rs can provide. I just cant find out the flow differnce of the t2 and t3 turbines which directly impacts boost response.

[Monooxide]

Like I had mentioned, I don't know a lot about the idea of twin turbocharging. I have had no reason to look into it. They were just ideas.

For what it's worth the T2 .64 A/R is usually around 14~15 lb/min. and the .63 T3 is around 21~26 lb./min.

[Boostage]

That helps. so two t3's should make the power I want :)

[Monooxide]

That helps. so two t3's should make the power I want :)

Exhaust flow doesn't really correlate 1:1 with Compressor flow, if you have calculated exhaust flow in lb./min with the 45-50 number you found then sure. But I am pretty sure that two .63 A/R T3s would be on the big side.

42-45 lb/ min corrected for the exhaust side is like a T4 ~1.15 A/R. Just a heads up.