I would like to know what size t3 turbo back is equivalent to the size of a T4 .68 SC61 ? Also is a SC61 with a T4 .68 back end too laggy or is it just the right size for a SR20DET Silver top with stock internals except for a Cormetic HG to net app 400+ whp safe ? I plan on placing the SC61 turbo on a modded GTiR manifold with a T4 flange along with a Tial 44mm wastegate.

What Car? , Whats Specs/Parts? and What Goals you plan on acheiving? Street or Full Drag? ETC

I would like to try for 400whp and will be going with an Aftermarket GTiR ECU, Apexi SAFCII, 300ZX Twin Turbo MAF, GTiR manifold with a T4 flange,3.5 inch exaust( according to funds will keep my current 3" setup) , Tial 44mm wastegate , 750cc injectors and a Greedy electronic boost controller. With concerns to fuel to feed the engine I already have an intank Walbro 255 and I will be beef up things with a BOSH inline pump with a surge tank.Everything in the engine is stock except for the Cormetic Headgasket. If I get into the 400whp range within a month after I will work up the GTiR 4 throttle intake setup. "Head work" and so forth will follow once I go over 400whp. The weak part of my setup so far is the gearbox which would be upgraded to the Big Spline SR20 hydraulic box with an lsd upgrade. I know it's not easy as it sounds but hell or high water I'm gonna get there.

Why do you want a T4 Back, SC61 T3T4 is a good go as it is for that amount of HP.

Why do you want a T4 Back, SC61 T3T4 is a good go as it is for that amount of HP.


It was what I want and won't be changine it period. All this is in preperation for the 600whp project later down the road. So back to the original question. A T4 .68 backend is equivalent to what size T3 backend ? I was told it is almost the same size as a .86 T3 backend. Is this true ?

Come on guys no one can give me some answers ?

It was what I want and won't be changine it period. All this is in preperation for the 600whp project later down the road. So back to the original question. A T4 .68 backend is equivalent to what size T3 backend ? I was told it is almost the same size as a .86 T3 backend. Is this true ?

So, it won't matter what size the t4 for is compared to a T3. If you'r plans are to hit 600WHP, keep the T4, use low boost for your current setup, you can upper the boost for the new engine setup.

So, it won't matter what size the t4 for is compared to a T3. If you'r plans are to hit 600WHP, keep the T4, use low boost for your current setup, you can upper the boost for the new engine setup.


The T4 backend I got is a .68 but I just want to have an idea as to where my boost might come in at... also I would like to know what size T3 backend is equivalent to the T4 .68 backend. My Whp goals are around 500 with some room to go. I will be going with a GT42R T3/T4 with a T3 .86 backend on a twin scroll manifold along with dual 38mmwastegate setup to reach the 600whp marker after.

I got another question.. If I choose to use the GTiR manifold and change the flange for the SC61 to bolt with a Tial 44mm wastegate what rpm should I start seeing boost on a stock engine with a Cormetic HG ?

ok if your using a modded gtir mani your killing your flow number one which is going to hurt your spool, the gtir mani is good for a t2 setup but the runners are small when ur going to be using a t4, not to mention the clearance issues when it comes to that t4 exh housing, number 2 the 255 walbro is fine for the power your going to be making for now.

ok if your using a modded gtir mani your killing your flow number one which is going to hurt your spool, the gtir mani is good for a t2 setup but the runners are small when ur going to be using a t4, not to mention the clearance issues when it comes to that t4 exh housing, number 2 the 255 walbro is fine for the power your going to be making for now.

All that you said is understood. I know the flow will be hampered because of the GTiR manfiold. I will be changing the manifold later on but I just want to have an idea of a few things ** I bolt the turbo up. I was told that I won't make 400whp with stock internals by some local guys down here. My mission is to prove them wrong. later to come will be will be a fully built engine with all the bells whistles with a few parts that I won't post as yet.

So back to the original questoin. Which T3 backend is equivalent to a t4 .68 SC61 backend ?

bump

Approximately 1yr later and I got pics for you guys.. I'm almost complete. The car has been down for quite a while, I got access to vehicles so I got too comfortable for almost a year lol. So far I have 99% of the parts I need just waiting on a manifold and wastegate. I changed things up a bit and did some work on my gearbox. I'm running an Autech pulsar fwd gearbox with the P11 fin cooled gearbox housing. The gearbox originally was a cable type and I had it changed to hydraulic. Currently the vehicle is totally scrapped out but in a few days humpty dumpty will be back together again. lol

Pics of the stuff I have purchased will be posted between now and weekend.

Here is a list of things so far..

Mines GTiR Ecu
300zx twin turbo maf
1000cc Precision injectors
New fmic ( large 3.5" thick )
Blitz blow off valve
HKS 40mm wastegate ( may change for a tial 44mm )
HKS mushroom filter
3" HKS Dragger exhaust(new model from japan)
HKS EVC III Boost controller ( EVC 6 will be in hand by January )
Bee R Power builder
SAFC Neo
Manifold ( not in hand as yet but it being custom made right now)