modify this turbo or get a different one?

[madmike]

heres the story in short...

got a free grand national turbo (tbo34 that i was going to rebuild for my 3400 swap in my 96 grand prix, i got a rebuild kit for it with the 360 thrust bearing and then... the snow ball effect happened and i think the turbo would be too small and ive already fabbed the system up. should i upgrade the turbo i have (new housings, wheels &/or turbine), get a lager grand national model, or go with an entirely diff set up? if so what should i be looking for?

this is my engine and set up thus far

im looking for about 300-350 hp at the wheels and this wil probly never see the track

3400 .20 over wiesco forged pistions
arp main studs and rod studs, arp head bolts
mls head gaskets
9 to 1 compression
mild porting of the heads (gen lll) ls1 springs
reground cam 214 int 220 exh .480 lift with 1.6 rockers 114 LSA.
log manifolds 1.5"
3" down pipe, no cat, dual split at the rear and no mufflers
255 fuel pump and aeromotive regulator
2.5" intercooler tubing
2.5" same side inlet/outlet 22"x6"x3"
evo turbonetics waste gate
hks blow off



this was to be an extremly mild set-up with a bone stock junk yard motor but not anymore lol

funny how a build can get out of hand in a hurry lol

[1988GTU]

I don't see how that stock GN turbo will be too small... ???
They support the 3.8's into the 12's with some alky/meth and a stock IC. I say rebuild it.

[mrsleeve91]

I personally got a Holset HX35 for my mild 2.8 fiero build. (they come on 2500 and 3500 dodges w/ the cummins) Now dont say its too big cause it comes on a 5.9L, diesels run about half the rpms so a 6L diesel is good on a 3L gas engine. I chose holset cause they are good for about half a million miles!! Ask any diesel shop.. And they have great efficency! Also can run 35+ psi all day long. On my 2.hate it saw full boost by 3000-3200 and was limited to 15 psi.

But I digress, the one from a GN would problely be fine, if you have that much invested already. The only problem is it does not have very good efficency, so the longer it runs the worse it will preform. Short runs you'll never know. I drove mine across the country so...

[1988GTU]

I personally got a Holset HX35 for my mild 2.8 fiero build. (they come on 2500 and 3500 dodges w/ the cummins) Now dont say its too big cause it comes on a 5.9L, diesels run about half the rpms so a 6L diesel is good on a 3L gas engine. I chose holset cause they are good for about half a million miles!! Ask any diesel shop..

The diesel engines run at a low RPM correct, the holset will last a long life on a diesel, also true. Put that same turbo on a regular old gas car and watch it's life go down by half since gas engines operate at a higher RPM than diesels. Put a turbo from a gas engine on a diesel engine and that turbocharger will last 2x as long as it would normally. This is all depending on maintenance and many other factors. IIRC the diesels huff out a lot different exhaust pressures.

[nocutt]

The turbo is fine, especially if you are properly intercooled ( it actually can take a grand national into the 11s even lower but this is more complicated). The point here is it can provide the airflow...the issue is how much airflow do you want? For 300-350WHp, you have to flow at least ~35lb/min of air. For pressures up to 2bar it will be perfect since it will be mostly street driven, the turbine allows for very quick spool...
hths

...But I digress, the one from a GN would problely be fine, if you have that much invested already. The only problem is it does not have very good efficency, so the longer it runs the worse it will preform. Short runs you'll never know. I drove mine across the country so...

Efficiency is relative here, distance has nothing to do with it...some of those engines are still on stock turbos!! + except you know what the comp map looks like then that is really far-fetch point to make on efficiency

BTW diesels run at a much cooler EGT, less corrosive fuel and as already mentioned less operating speed this helps longevity in comparison to gasoline
hths

[madmike]

cool, i wasnt sure because i originally intened on a stock build but then upgraded the engine far past what i wanted in the begining....this always seems to happen to me lol

thanks for the help!! any other suggestions are welcome

[mrsleeve91]

The diesel engines run at a low RPM correct, the holset will last a long life on a diesel, also true. Put that same turbo on a regular old gas car and watch it's life go down by half since gas engines operate at a higher RPM than diesels. Put a turbo from a gas engine on a diesel engine and that turbocharger will last 2x as long as it would normally. This is all depending on maintenance and many other factors. IIRC the diesels huff out a lot different exhaust pressures.

OK a gas engine that has the displacement has to run at twice the rpms to put out the same volume. A 6L at 3K will put out the same cfm's as a 3L at 6K rpm's. Make sense?


Im just saying there are alot of factors, while all turbos make boost just different times and potential of boost with different engines and displacments. I have a pefference and thats all I was stating.