td4.2 turbo size question - rb25 turbo, big enough?

[sidewayz]

hey

looking at doing a turbo conversion to my gq td4.2. was originally goin to just use a stock gu turbo to keep things nice and simple but i had this thought today.

im about to upgrade the turbo on my r33 skyline (rb25det). how would a std rb25 turbo perform on a td4.2? i have a feeling it may be a bit small and run out of puff? but a visual size comparision and its fairly similar to stock gu turbo.

im not looking to build a monster, just would like a healthy power increase from the stock n/a turtle.

cheers

matty

[dave_str]

Mate use a S15 Silvia or a HN14 GTIR Pulsar turbo, ball bearing T28. Not really cheap but great turbo's.

Dave.

[sidewayz]

anyone?

[NutterGQ]

too small, exhaust wheel and housing all no good for it, will be on boost non stop.

[sidewayz]

yeah i had a feeling that was the case

[sudso]

A mate is putting a turbo from an RB20 on his TD42. I dont know if its smaller than the RB25 turbo but the bloke who makes the exhaust manifolds for them to fit the TD42 has the same set up on his own Patrol.
My mate reckons this things "boots up" from 1000rpm but its set up so its not on boost all the time being such a small turbo.
Will post on the progress of this. He's still got a few more bits and pieces to get before installing it all.
It'll be interesting to see how it performs on a 600K old engine lol.
cheers

[sidewayz]

yeah an rb20 turbo is smaller then a rb25.

will be interested to see his results.

[NutterGQ]

results will be boost at idle and all throttle no matter how small, with nothing up high...you may find it chokes as early as 4000rpm, dont bother doing something if you wont do it right.

[madrolla68]

results will be boost at idle and all throttle no matter how small, with nothing up high...you may find it chokes as early as 4000rpm, dont bother doing something if you wont do it right.

Chokes up as early as 4000, how far do you want to rev the thing????

I agree it may be a tad small.

Matt

[adriand82]

results will be boost at idle and all throttle no matter how small, with nothing up high...you may find it chokes as early as 4000rpm, dont bother doing something if you wont do it right.

Chokes up as early as 4000, how far do you want to rev the thing????

I agree it may be a tad small.

Matt

x2
mine never goes past 2500 lol

[NutterGQ]

it doesn't because it wont, why turbo the car if your happy making max power all 50hp of it at 2500 rpm.

[GQ4.2]

the garret "disco potato" which was sold in the group buy a few months ago, anyone installed one of these and how were the results???

[twodiffs]

the garret "disco potato" which was sold in the group buy a few months ago, anyone installed one of these and how were the results???

Mate..thats an excellent question and I hanging out to get some feedback too Coxy..anyone??

[Patroler]

Dunno but i would have thought an rb25 being a fairly efficient motor and all - twin cam etc, and the fact that it revs pretty high (compared to a td42) would have the potential to flow (and therfore require) more air than a td42, i know the td42 is a larger capacity but it just won't have the same pumping efficiency as the rb25, and a td42 is probably most happy making its power between 2-4k.

Also considering i asked a turbo diesel expert about putting a disco potato on a td42 and he said better results would be obtained trom the next size down - plenty of people use disco potatoes on sr20's (thats what they were developed for)

Anyone know how much power a stock rb25det puts out? im guessing it'd be about 180kw, once again i'm only guessing but if the turbo can flow enough air to make 180 odd kw i would have thought it should be good enough to get a td42 to 100-120 at the wheels?

happy to be corrected...

the thing to do would be to find out what turbo youve got, get compressor map and work out what airflow you require and plot it - seing where it comes out at when overlaid on the map - there are programs on the net which can help you.

Also, depending on what flanges it has it may be a simple case of setting it all up and if it does infact boost too early (if you researched what other turbos you can get with that flange) you may be able to just bolt on a bigger turbo, that way youve lost nothing. T28/T3 come to mind, no doubt the info is out there, just seems like a waste to do nothing with it.

[sidewayz]

std turbo rb25 wil make between 180-190kwatw. (with supporting mods)

rb25 is t3 flange

the std gu turbo manifold i have is also t3 flange.

[GQ4.2]

I used to own a VL commodore a few years back and put a RB20DET motor in it

all the standard turbo's off the RB20 & RB25's use a ceramic exhaust wheel, any boost over 14PSI will see it snap off the shaft

when my RB20DET was stock it made 146rwkw @ 14PSI

Honestly I think you would be best looking at the Disco Potato size or just ring up JPC etc who build comp rigs and ask them to make you a turbo at least they know what will work best having years of experience turboing TB & TD 42's

[Simo63]

results will be boost at idle and all throttle no matter how small, with nothing up high...you may find it chokes as early as 4000rpm, dont bother doing something if you wont do it right.

X BAZILLIONS. You will be wasting your time as a small turbo will be boosting at idle or just over and have no improvement up top at all.

[figjam_1985]

About to use a t28 off a SR20det on the 4.2, its the same thing that turbo glide used to use in there first kits

[Patroler]

std turbo rb25 wil make between 180-190kwatw. (with supporting mods)

rb25 is t3 flange

the std gu turbo manifold i have is also t3 flange.

There ya go then, if the turbo is in good nick - seals and bearings - (or bushes) what have you got to lose.

I'm not sure why people are so adament that it is such a small turbo when it comes standard hooked up to a motor producing 180kw,
its not as though you're putting a turbo off an 1.5L ET pulsar on it...

Once again i really can't see that you've got anything to lose, if it works (keep us posted) you'll save a grand or so, and if it doesn't work and makes boost at idle (i'd be interested to see) you can buy a bigger one and you'e only lost a couple of hours and gained some priceless experience.

[NutterGQ]

it doesn't work like that, just because the cold side will support it doesnt mean the hot side will.

[coxy321]

the garret "disco potato" which was sold in the group buy a few months ago, anyone installed one of these and how were the results???

Mate..thats an excellent question and I hanging out to get some feedback too Coxy..anyone??

Sorry guys - i cant remember who bought the turbo in the group buy. Whoever it was go the turbo with the smaller exhaust turbine housing.

I think along the lines of what a few of you have said re: alternative turbos. A 2/2.5 L engine coming on boost at 3000RPM and not running out of exhaust housing flow until 6500RPM - i would think that although say a TD42 and RB25DET have completely different flow and efficiencies, i cant see why an RB25DET turbo wouldnt work on the TD42.

Unless you get a turbo with a rediculously small exhaust housing - your not going to have boost on idle.

Different horses for different courses. I'm trying to track down a turbo with a T3 flange for mine, possibly thinking VL turbo unit. I have one on my 180B and i think the rev/power range would suit the TD42 ok.

Coxy

[josh_d20]

hey

looking at doing a turbo conversion to my gq td4.2. was originally goin to just use a stock gu turbo to keep things nice and simple but i had this thought today.

im about to upgrade the turbo on my r33 skyline (rb25det). how would a std rb25 turbo perform on a td4.2? i have a feeling it may be a bit small and run out of puff? but a visual size comparision and its fairly similar to stock gu turbo.

im not looking to build a monster, just would like a healthy power increase from the stock n/a turtle.

cheers

matty

hey mate if u wont a t28bb turbo i can get them brand new for $500

[monkeycritter]

hey

looking at doing a turbo conversion to my gq td4.2. was originally goin to just use a stock gu turbo to keep things nice and simple but i had this thought today.

im about to upgrade the turbo on my r33 skyline (rb25det). how would a std rb25 turbo perform on a td4.2? i have a feeling it may be a bit small and run out of puff? but a visual size comparision and its fairly similar to stock gu turbo.

im not looking to build a monster, just would like a healthy power increase from the stock n/a turtle.

cheers

matty

hey mate if u wont a t28bb turbo i can get them brand new for $500

Is the T28bb a garrett or hybrid?

[josh_d20]

hey

looking at doing a turbo conversion to my gq td4.2. was originally goin to just use a stock gu turbo to keep things nice and simple but i had this thought today.

im about to upgrade the turbo on my r33 skyline (rb25det). how would a std rb25 turbo perform on a td4.2? i have a feeling it may be a bit small and run out of puff? but a visual size comparision and its fairly similar to stock gu turbo.

im not looking to build a monster, just would like a healthy power increase from the stock n/a turtle.

cheers

matty

hey mate if u wont a t28bb turbo i can get them brand new for $500

Is the T28bb a garrett or hybrid?

garrett

[coxy321]

hey mate if u wont a t28bb turbo i can get them brand new for $500

Post up the specs so everyone knows exactly what unit your talking about. You might get a few sales if your lucky!

[sidewayz]

there is a fair few varieties of garret t28bb

post up specs and garret numbers

[A.J.]

I could be interested too
Specs! Please.

[brad-chevlux]

the garret "disco potato" which was sold in the group buy a few months ago, anyone installed one of these and how were the results???

Mate..thats an excellent question and I hanging out to get some feedback too Coxy..anyone??

Sorry guys - i cant remember who bought the turbo in the group buy. Whoever it was go the turbo with the smaller exhaust turbine housing.

I think along the lines of what a few of you have said re: alternative turbos. A 2/2.5 L engine coming on boost at 3000RPM and not running out of exhaust housing flow until 6500RPM - i would think that although say a TD42 and RB25DET have completely different flow and efficiencies, i cant see why an RB25DET turbo wouldnt work on the TD42.

Unless you get a turbo with a rediculously small exhaust housing - your not going to have boost on idle.

Different horses for different courses. I'm trying to track down a turbo with a T3 flange for mine, possibly thinking VL turbo unit. I have one on my 180B and i think the rev/power range would suit the TD42 ok.

Coxy

The stock RB25 turbo we used on an RB30 twincam build, would choke the engine at about 6000rpm, (it showed around 175rwkw on 12psi) .

the TD42 is hardly a high reving engine, and when offroad we aren't really looking for high rpm power, we are looking for low down grunt and smooth power, we don't want to be waiting for the power to come.

i say bolt the thing on and drive it. if it works for you then keep it. If not there are any number of turbos to choose from that will bolt straight in.

[macneil]

the garret "disco potato" which was sold in the group buy a few months ago, anyone installed one of these and how were the results???

Mate..thats an excellent question and I hanging out to get some feedback too Coxy..anyone??

Sorry guys - i cant remember who bought the turbo in the group buy. Whoever it was go the turbo with the smaller exhaust turbine housing.

I think along the lines of what a few of you have said re: alternative turbos. A 2/2.5 L engine coming on boost at 3000RPM and not running out of exhaust housing flow until 6500RPM - i would think that although say a TD42 and RB25DET have completely different flow and efficiencies, i cant see why an RB25DET turbo wouldnt work on the TD42.

Unless you get a turbo with a rediculously small exhaust housing - your not going to have boost on idle.

Different horses for different courses. I'm trying to track down a turbo with a T3 flange for mine, possibly thinking VL turbo unit. I have one on my 180B and i think the rev/power range would suit the TD42 ok.

Coxy

The stock RB25 turbo we used on an RB30 twincam build, would choke the engine at about 6000rpm, (it showed around 175rwkw on 12psi) .

the TD42 is hardly a high reving engine, and when offroad we aren't really looking for high rpm power, we are looking for low down grunt and smooth power, we don't want to be waiting for the power to come.

i say bolt the thing on and drive it. if it works for you then keep it. If not there are any number of turbos to choose from that will bolt straight in.

X2

you gotta remember that the TD42 revs out at 4400 torque on the diesel is at like 1900 rpm thats where you want your boost.. if u waited any longer for it you would be changing gears.. i never rev my td42 above 3000 and it only goes there if there is a big hill..

ive heard that the garret t28 is the best matching turbo from a few diesel mechanics i will be putting one on when the time comes..

[chunderlicious]

hey mate if u wont a t28bb turbo i can get them brand new for $500

Post up the specs so everyone knows exactly what unit your talking about. You might get a few sales if your lucky!

im up for 2 if the specs are right.