I understand that a ball bearing turbo will always have better transient response as well as decreased lag compared to its journal bearing counterpart. I guess I was more curious as to whether or not anyone used these in journal bearing form and their opinions of it. I have had a gt35r with a melted exhaust wheel that I was barely able to sell only for the housings. I know this isn't the turbos fault but it sure did suck to try and sell.

I know that transient response is something that can't be seen on dyno charts but as far as lag is concerned, how big is the difference between the two? When can peak boost be seen on a 6262 journal bearing in .63ar and .82ar configurations? I can deal with some lag as I used to run a twinscroll journal bearing T4/T67 .84ar on a b16 (7.8:1 compression) Integra.

Thanks for the response Ted B.

 

The difference in lag is typically at least several hundred rpm, which is more than enough to be off putting and render JB an inferior option. For example, I recall one member with a JB SC61 that didn't hit 20psi until somewhere beyond 5000rpm, which is slower than a 900whp capable HTA3794. Unacceptable.

You have a motor with a practical rev limit ~8000rpm, and it will begin to drop mechanical efficiency and generate appreciable internal friction prior to that point (why 2.0L are the drag kings). You'll want as much area under the curve as you can get. My advice is drop JB like a bad habit. The melted turbine wheel on the GT35R was a tuning issue and not the a fault of the turbo or its CHRA.

As for the turbine housing, anything greater than ~650whp is where the .82 A/R starts looking better. But it comes at a cost, that being losing a little more spool time. It's always a compromise, but a JB turbo is a step backward and a compromise you should not make.

 

Can some one help me out w my question.. I just bought a 6262 t4 w 81 ar... will a t4 81ar to big and laggy for a stock block... was told t4 81 is equivalent to a t3 1.06.

 

Not much about this combination makes good sense.

Basically, this will amount to a late spooling setup with an engine that can't reliably handle the power or rpm needed to salvage much of a powerband. The situation can be improved with a .63 A/R T3 hotside, but when the peripheral hardware needed to fit it is considered, the end result will be pricier and typically inferior to popular alternatives (e.g. FP Red or Black).

It wasn't mentioned if this turbo is a BB or journal unit, but if the latter, I'd forget about fitting it to an EVO altogether, stock block or not. If it is a BB unit, and if you're determined to hang onto it, it's time to start saving for a new engine and supporting hardware.

 

Thanks for the reply...Its a jb 6262. I traded a hx35 that I had laying around and $200 for the 6262. I'm looking to make more power and lowering my tq at the same time at this current time with my stock block... currently @ 465/390 on a old to green on e85. ....thanks for the advice I will be getting a .63 hot side and I have a 2.4lr at home as well.

 

The reason why we don't use JB turbos that size is because those who've done it found the additional ~500rpm worth of lag and slower transient response unacceptable. Factory style turbo cars will easily outperform this setup.

A 'good deal' isn't good when the end result is a disappointment. My recommendation is to drop that turbo like a bad habit and putting the funds required for the supporting hardware toward something that is a virtual direct swap for your present setup, like an FP Black.

Just FYI.