Gt42 On Rb25det?

[Young GT-R]

This turbo is a monster with a 1.15 A/R exhaust, but has anyone done it and what lag can be expected? Boost to kick in at 5k or a bit better than that?

Advice appreciated.

FMIC

Haltech

Stock internals

3" full exhaust etc.

would only be running 1 bar.

[Morgs]

Bit too big...

I wouldn't expect boost until 5500rpm or more...

[paulr33]

boost at 5500rpm

stock internals = time bomb

lag city

pick something more suitable, ie: anything under gt30 would be suitable

[paulr33]

btw 1 bar on a gt42 is a MASSIVE amount of airflow

it will go bang. injectors lean out, boom.

you would want a 4" exhaust on it also

[R31Nismoid]

forget 1st and 2nd gear

wont make squat... no power, no boost.

motor is just too small to get it going soon enough. 3rd/4th you might get into the 5500rpm range... if your lucky

[CruiseLiner]

try a hks t51r i reckon, will make more power, for about 2 min

[DoughBoy]

I bolted on a HKS T51R Kai BB for shits and giggles to a stock RB25 longblock. Had a Greddy plenum/115mm intercooler/PowerFC.... was a rocketship i tell ya! Had to flatchange gears to get some boost into the system, made next to no boost in 1st gear. Only ran 9psi, was a bit timid with boost at the time. Had to bump up the rev limit on the dyno to 8500, when it hit boost at 7k it fried the tyres.

Oh, made power for alot more than 2 minutes. Took it off out of frustration (and had another turbo to try out). Even tried out circuit racing at Eastern Creek with it, Roy and I couldn't stop laughing at it (well, until it fouled the plugs and nearly had to be towed off).

Visual appeal was at a maximum though.

[paulr33]

haha

what a lag monster

boost comes on at 5357rpm

[DoughBoy]

It wasn't a lag monster, it was a Skyline built for cruising. You could call it a Skying.... or a Cruiseliner? heheh

[paulr33]

[Tex Willer]

http://i69.photobucket.com/albums/i70/tjomi/DSC01157.jpg

Was going for the 42, but I chickened out because it scared me unpacking it.

Went for littlebrother GT40, and that one even looks too big.

The little one is a 600hp Precision turbo!

I`ll give the GT40 a try.750hp rating. Wiseco/Crower internals.

[Young GT-R]

It was only by chance that I found one so I figured I would ask.

I really want a GT30/40, GT35/40 or a HKS 3037S something equivalent which is proven on the RB25's.

But thanks for the input, like I said appreciated.

[fire_bringer_]

Im goin with gt3540 with nos + forged internals .. It should give 300+kw but If u dont wanna go as far then stick with gt30 range. from I have seen u get good power 250 to 300kw with no need to change anything else

[Roy]

It wasn't a lag monster, it was a Skyline built for cruising. You could call it a Skying.... or a Cruiseliner? heheh

Those guys that were with me the night you gave me a lift to the Swans game still pull their d1cks over how it went, and more imprtantly how it sdounded when it spooled and hit boost.

It was so cool, the sound alone was worth every second you had to wait to boost.

[discopotato03]

This turbo is a monster with a 1.15 A/R exhaust, but has anyone done it and what lag can be expected? Boost to kick in at 5k or a bit better than that?

Advice appreciated.

FMIC

Haltech

Stock internals

3" full exhaust etc.

would only be running 1 bar.

I think its sufficient to say that an 800Hp turbo is a long way out of place on an RB25 , it would be extreme on an RB26 and laggy on a street driven RB30DET .

If you go this way and I strongly advise you don't , use the HKS version which is called T51R as it uses a smaller trim turbine than the Garrett marketed GT42R ie 76T vs 84T .

Very very laggy , very expensive and very likely to destroy your RB25 . Why bother .

Cheers A .

[discopotato03]

If it were me on a std RB25DET I would do the HKS GT3037 in 52 comp trim or ask GCG if they can make a similar combination up for you . A lot of people find the GT30R (the real one which is same cartridge as GT3037 56T) is laggy and you have to push it to get good squirt which is a pain in a road car . Small AR turbine housings only make them surge so that 52T compressor is a must and makes 40lbs airflow in .50AR TO4E cover so 400 should be no prob .

A bit OT but we need Garrett Japan to make GT30 and GT35 turbines in smaller trims than 84 , the current GT40R uses a 78T and the High Kost Spec GT42R (T51R) a 76T turbine .

Cheers A .

[StockyMcStock]

if it's any use as a comparison, i have a GT40 with a 1.34 A/R rear housing on my RB30 DET. standard cams, custom plenum and exhaust manifold.

1st gear: lucky to see 4psi of boost at 6000rpm. full traction.

2nd gear: 10psi around 4800rpm (hard to tell) lots of tyre frying. goes from 70km/h to 130km/h in the space of about 1 second. this gear feels roughly three times as fast as first did.

3rd gear: 10psi at 4000rpm. traction is borderline. very fast gear up top past 150km/h.

4th gear: load it up and you'll have 10psi at 3500. by then you're doing close to the sound barrier anyway so you better stop quick.

on a 25 even the GT40 with smallest rear would be stupid, let alone the one i have.

p.s. makes great noises though, this turbo!

[Tex Willer]

Precision makes smaller exhausthousings for the GT40. This one is A/R 0.81 with 69mm outlet.

They call this turbo GT4067R. Rollerbearing core. 750hp rating. 1.5bar/22psi at 4800-5000 rpm with some good cams. I`ll post my dynopaper when done building/ mapping.

[paulr33]

a 750hp turbocharger is hardly suitable for a stock internals R33

[Tex Willer]

100% agree