ashtons300zx

I searched and couldnt really find anything in relation so figured id throw this out there. On my car I plan to run a T4 open .81 turbine housing 6766 billet turbo. I had originally planned to just use the journal bearing turbo. My goal is around 800whp and will probably take about 35-38 lbs of boost to get there. Seeing the thread with all the bent shaft journal bearing turbos when running them in the 30-40psi range has me a bit worried more than anything else. The car is primarily a drag car that may see very very little street use for meets and stuff but thats about it.

Question though besides the issues with the journal bearing turbos bending the shafts and breaking off compressor wheels, what is the spool characteristics like ball bearing vs the journal bearing, More so in a situation that say you spin 2nd gear really hard and shift too early bogging 3rd, how quick is the ball bearing to spool back up vs the journal bearing. I know the ball bearing itself on a dyno will spool around 200-300 rpm quicker but what about plain out response during a bog situation or say an slow shift situation where you would have lost more air volume out the bov during that shift vs a quicker one.

In short is the bb turbo worth the extra 800 bucks vs the journal bearing or do you think the journal bearing will still perform just fine.

Gunmetal_B20_Hatch

iTrader: (9)

I seem to hear LOTS of stories about the journal bearing variants not working out, but the ball bearing ones seem to be nearly bulletproof. Thats what swayed me into getting a ball-bearing Precision unit.

I cannot compare journal vs. BB spool times for you, but I can tell you this... When I purchased my billet 6262BB I was constantly worried about it being a bit too large for my setup(see sig) and causing a good bit of lag mainly due to being non-VTEC and not turning as many RPM. I was extremely surprised at how quickly the turbo came into boost and am now looking into a billet 6765BB. With the 6262, I can start all my pulls from 3500rpm and by 4300-4500rpm have 20psi boost up to 8000rpm redline. Building boost after shifts is effortless and nearly instant.

ashtons300zx

im using the SR20VE motor so it should still spool up the turbo pretty quick with the sr16ve cams im going to be using. Awesome for big turbos. Cam switchover point will be around 5100 and should hold a powerband out to somewhere in the 9500-10000 rpm range, im hoping to see full boost by about 6000 or so to give me a very wide powerband. But we will see when the time comes. Motor is a 2.0L as well and running 9:1 compression.

Thanks for the input, Im really debating just bitting the bullet and getting the bb unit if it means it will last longer, spool back up quicker during slower shifts or bogged gears due to spinning and take the abuse of the higher pressures without worries.

Here is a vid of my t67 h.o t3 .82 housing of my last setup with the sr20de highport head w/ c2 cams, S&R's, and reving to 8700. I had the slick pressure too high in these vids and my two step too low. I pulled some better launches in later runs pulling a 1.61 still bogging a bit but ran into some issues and had to pack it up due to rain. You can see what i mean by spin/bog, spin/bog, spin/bog. I had a high trap speed of 137 doing the same thing in previous runs.

http://www.youtube.com/watch?v=2zlI1O1gkDE

I never got a good full run after that but that was with about 650whp on that t67. Basicly you can see how much time i lost from the slow bogged shifts and the time it took to respool back up. I want to cut that time down if that happens in say 2nd gear and hit 3rd too early. Again its all seat time to fully dial the car in but id still like to get the best times possible even with small errors.

welfarepc

ive been using my 6262 journal for 2 years, no issues

92redhatch

I'm at 30psi and I have no issues on my jb 6765. I'll be tuning for 35+ psi soon.

Cimburke23

why would you go to a bigger turbo? the 6262 is capable of 700+whp. i just made 647whp on a stock sleeve, stock bore gsr. hoping to up the injector size and see if itll hold 700 on stock sleeves. to the OP, my journal 6262 with a .68 t4 housing spools 25psi at 6000

ashtons300zx

Thanks for the replies, keep em coming.

Its not necessarily the spool time im worried about, I figure if i have a powerband from 6k-9500+ then spool time isnt really necessary since in drag racing im not gonna be out of that powerband unless i really bog a gear. More so im worried about response of the bb vs journal during slow shifts getting off and back on the gas or even during decent shifts where there might be slight lift but still quick. How quick is the bb to respond back with full power vs the journal. Things like that can make a huge difference in time and trap speed.

Then of course the reliability of them at 35+psi one vs the other.

AllShowNoGo727

iTrader: (1)

29 psi here 6262 billet BB no issues so far... knock on wood

0xenocron

It's probably a 300-400 rpm difference which in drag if you bog...I don't think you are going to feel any difference. It's more for the street and the on/off transient response.

SLIM NOTHING

x2. you shouldn't be falling out of boost anyways

k420

bb ftw

swapit

I run 40lbs without issue on my 6765 bushing.I had it for 2yrs now but dont dd the car

ashtons300zx

Yeah so far I dont think I can justify the extra 800 bucks. If it was a 3-400 difference id say yeah without a doubt but 800's a pretty good chunk for just some extra spool time. And your right once the car is all dialed in and feel comfortable putting the extra abuse on the trans with some quick shifts I wont have to worry about lag time or falling out of boost.

In the vid I was taking it easy on the 2-3 and 3-4 shifts but either way would have bogged the next gear pretty bad just simply from the spinning. Ill have a much fatter powerband to work with too so it shouldnt be an issue.

Im thinking Journal bearing it is.

twkdCD595

6265 journal here for a couple years so far as well, 29ish psi peak boost I have run.

shawty22

Lets bring this thread back up. But I'm more looking to see if anyone has the spool time differences between the JB and the BB turbos. Boost graphs between the two? Any intel would be nice.