2H turbo - how much boost?

[chunks]

Hey fellas,

I just bought an 89 GXL cruiser powered by a 2H running an old ARB turbo kit which has been on the car most of its life (it has 278 000 km), it also runs a 3" exhaust with a straight through muffler. I'm getting a front mount intercooler fitted soon and just wanted to know what boost i can run safely without sacrficing long term reliability? I was think 10 psi should be ok, i'm not sure what its running right now as i dont have a boost gauge installed yet. The car has been properly maintained all its life and runs like a dream, but a tiny bit more power would be nice for big hills.

Cheers,
Bill.

[sixdeetoo]

you could happily run 10psi no long term.

with FMIC could even run 12-14psi

Referals like this directed to Dumbdunce of this board - Yoda of Toyota

[dibbz]

My ARB kit peaks around 8psi in the factory configuration. Does me fine.

EGT's get over 400 with a bit of load up inclines the highway doing 110, I guess it'd point more towards 500 if the hill was kinda big and I was towing more, which would be enough EGT for me :)

Do a search for Carts' 60 it's all in there..

[dumbdunce]

Dumbdunce - Yoda of Toyota

it's the pointy ears isn't it.

EGT's are the main key. 14 is pretty much the absolute upper limit before you need internal modifications, and keeping EGT's under about 550C peak and 350C cruise will keep it alive. with indirect injection the upper limit is set by pumping inefficiencies through the precombustion chamber (almost all of the air your engine ingests has to be pumped through holes the size of your little finger nail) and the pressure differential limits of the injector design - if boost is too high you start pumping combustion product back into the injector, which is obviously bad. With the 2H there is an added danger of melting the piston crowns because the engine has no piston skirt oil cooling, but this can be added if you open the motor and start fiddling inside.

[chunks]

Thanks fellas, i did search but i just wanted to clarify 100%.

I don't want to go overboard, just a little bit more power would be nice. I'd rather not get involved in engine rebuilds etc at this stage.

In regards to the intercooler, would an intercooler off a s4/5 rx7 be too small as i have an over-supply of these. Also what size piping should i go i was thinking 2.5" ? Lastly with hooking up a blow off valve on a diesel, where do you run the vacuum line off the top of the bov to?

Thanks again guys,
Bill.

[dumbdunce]

Thanks fellas, i did search but i just wanted to clarify 100%.

I don't want to go overboard, just a little bit more power would be nice. I'd rather not get involved in engine rebuilds etc at this stage.

In regards to the intercooler, would an intercooler off a s4/5 rx7 be too small as i have an over-supply of these. Also what size piping should i go i was thinking 2.5" ? Lastly with hooking up a blow off valve on a diesel, where do you run the vacuum line off the top of the bov to?

Thanks again guys,
Bill.

any intercooler is better than none. 2.5" is good, 3" is better, use whatever matches the ports on your intercooler. build it without the BOV first and see how it goes, you might find no need if your intercooler volume is small and/or you don't go overboard with boost. there are two roads you can go down for vacuum - you can use an electric switch and an air solenoid and draw the vacuum off the vac canister for the brake booster (complicated but effective) or you can drill the manifold below the throttle butterfly, and work on balancing the BOV spring (you will need a much softer spring than for a petrol engine). this method is probably simpler and cheaper if you have a supply of springs to fiddle with.

[DIRTY ROCK STAR]

Thanks fellas, i did search but i just wanted to clarify 100%.

I don't want to go overboard, just a little bit more power would be nice. I'd rather not get involved in engine rebuilds etc at this stage.

In regards to the intercooler, would an intercooler off a s4/5 rx7 be too small as i have an over-supply of these. Also what size piping should i go i was thinking 2.5" ? Lastly with hooking up a blow off valve on a diesel, where do you run the vacuum line off the top of the bov to?

Thanks again guys,
Bill.

any intercooler is better than none. 2.5" is good, 3" is better, use whatever matches the ports on your intercooler. build it without the BOV first and see how it goes, you might find no need if your intercooler volume is small and/or you don't go overboard with boost. there are two roads you can go down for vacuum - you can use an electric switch and an air solenoid and draw the vacuum off the vac canister for the brake booster (complicated but effective) or you can drill the manifold below the throttle butterfly, and work on balancing the BOV spring (you will need a much softer spring than for a petrol engine). this method is probably simpler and cheaper if you have a supply of springs to fiddle with.

Having driven an 80 that DumbDunce Turbo'd (pre intercooler) I would have to say the difference is amazing.
the bloke is a wizard!!!!

[chunks]

Awesome thanks dumbdunce!!

A mate builds performance turbo cars from home and has all the gear required so i'm sure we can fit a decent intercooler and 3" piping and sort out a bov. I will also be getting it dynoed and the EGT's checked.

Thanks for all your help!

Bill.

[dumbdunce]

DumbDunce... is a wizard!!!!

see my pointy hat?