Gt42r Approx Spool Rpm?

[ltd351t]

New combo, not sure what rpm it will make +'ve manifold pressure or acheive full spool.

Stock BA six cylinder engine.

GT42-02R 76.4mm inducer, 1.15 TV(T6) rear, 4" dp.

Short runner possibly smooth log style manifold.

Running on LPG, intercooled.

Just after some opinions from people that have experience with this, would like to have some more info prior to ordering the converter.

The converters behaviour will vary depending upon how much power this makes, but I'm just after a rough guide as to when it might start making pressure, and when it may be fully spooled, Jeff from the converter shop said stuff like that usually wants 3500rpm stall, and I guess flash to 4500rpm or so.

I know this may have been covered before, haven't got time to search atm.

Edited 11/02/08 06:01 AM by ltd351t

[senna_T]

considering Garrett say you can use a 42r on engines from 2.0L to 8.0L I reckon 3500rpm would be enough to spool it on a 4L.

The effective boost range of this turbo will make it interesting when trying to launch on full boost if its still in a falcon!

[Ernie]

it comes on a bit later then that Pat. it will start making boost at 3500 but only about 6 to 8 psi and not much power. these are better at 25 + psi boost to make any type of good HP

ive used these turbos many times but on different applications and at 30 psi boost its not even whistling hard. my 9.9 @ 139 mph 1.41 60' run in my racecar was only with 20 psi boost and lazy as.Ive max out an eboost gen 1 at 40.7 psi boost and the turbo still wanted to go more.

the most ive taken a GT42R to is 45 psi............. GT42RS ( 1000 hp version ) we have gone 51.7 psi boost.

Ern

[ltd351t]

The unit I have is the 74.5mm ind 102mm exd, unsure of the turbine wheel or any other specs, apart from the 1.15 large flange rear, 5" v band outlet, etc.

The garret rating for my unit is 1000hp, it was originally purchased to go on a 5.8lt engine around the 650fwhp range.

I think its too big on this 4.0, but I'm going to try it anyway.

So does 3500rpm sound like a good stall speed?

I am unsure, something like 3500 maybe 9.5" might work well, give it some form of driveability but easy enough to flash it higher, I have no experience with the BA engines so its hard for me to judge.

Bell housing will be ordered tomorow but converter not until I have enough info.

Thanks for the replies

[ETM]

an engine dyno is really the only way to precisely know what converter to order.

the 1.15 housing is better suited to a drag car,I would look at changing to something smaller to give it more streetability.

[ltd351t]

Both options are too expensive for my budget.

[Ernie]

The unit I have is the 74.5mm ind 102mm exd, unsure of the turbine wheel or any other specs, apart from the 1.15 large flange rear, 5" v band outlet, etc.

The garret rating for my unit is 1000hp, it was originally purchased to go on a 5.8lt engine around the 650fwhp range.

I think its too big on this 4.0, but I'm going to try it anyway.

So does 3500rpm sound like a good stall speed?

I am unsure, something like 3500 maybe 9.5" might work well, give it some form of driveability but easy enough to flash it higher, I have no experience with the BA engines so its hard for me to judge.

Bell housing will be ordered tomorow but converter not until I have enough info.

Thanks for the replies

an engine dyno is really the only way to precisely know what converter to order.

the 1.15 housing is better suited to a drag car,I would look at changing to something smaller to give it more streetability.

I agree here too.

a smaller 1.00 or .96 housing will spool it faster then a 1.15. the bigger the rear housing the bigger the lag wil be.

if it has the 74.5 mm front wheel the it has a hp rating of 800hp and more than likely its a GT42R. the GT42RS has a 94 mm front wheel and is rated at 1000 hp. the 102mm outer cover is the exducer and will be on both turbos....... this channels air into the turbo.

they both will have a 82mm rear turbine wheel from memory. if anything get the 5 1/4 inch rear flange cut off and modified to suit a 4 inch v-band flange....... it will make life so much easier to get exhausts made.

it will be a good turbo for the BA motor and will be driveable but you will have to give it some boost to make it work

below is a GT42RS/45 modified with a GT45 cropped rear 88mm exhaust wheel and modified 4 inch v-band........flowed to 1400hp

Ernie

[2MUCHKW]

Both options are too expensive for my budget.

Does'nt sound like your um budget ... is going to give a good outcome! :wacko:

[ETM]

its the same turbo I have on my torana

gt4202r with 1.15 rear,as you can see its a big unit and not ideal for a street car.

I also machined my rear housing back to accept a 4" vband

[senna_T]

thanks Earn, I think what I was thinking about was more a trans-brake style spool up - if I'm not mistaken as to how this works. I completely understand the concept of efficient boost levels on all turbos, apologies if I missed it, but will this car be a full drag set-up, or still be street driven?