I was thinking about Turbos...

[MrFlibbles]

I spotted three boxes in the office the other day, containing some nice shiny new turbos for a some of out trucks.

I had a look at them and they were massive, but not entirely dissimiliar to my own. It got me thinking, its the trubo unit from a truck the same as a turbo unit for a car?

Can they provide and hold higher boost levels and are they laggy as a very laggy thing?

I'm not intending on doing it, just curious

[thong]

They work the same but most big trucks dont have wastgates,dont even think about shoehorning it onto your car it will just windmill and do nothing.

[speedy_thrills]

Hello MrFibbles, as mentioned truck turbochargers are not what you are looking for to increase boost. Even if you could rig up a waste gate mechanism it still wouldn’t necessarily provide more boost, however there are a number of ways your current turbocharger can be modified to increase boost/change boost characteristics. How exactly where you planning on coping with the increased cylinder pressures? That’s really your main problem.

[MrFlibbles]

MrFlibbles said:

I'm not intending on doing it, just curious

Like I said above, I'm merely interested in the theory - I know it wouldnt be workable in a car in practice, Im just intrigued as to the boost levels they run and if there are any internal differences.

[eliot]

Depends what size engine they are from. I have a rule of 50%, i.e. a turbo from a 4L truck will drive a 2L engine.
Exhaust housing is usally disproportiante from the compressor housing (i.e. the compressor is usally too small for a given exhaust AR)
The are others that say you can run Diesel turbos on petrol engines due to the higher exhaust temps, which is true - but there are numerous people doing it without issue.

Turbos on the left are a pair diesel units EACH one from a 6L truck, on the right a pair of T34's


>> Edited by eliot on Sunday 18th December 19:26

[chuntington101]

i think it more depends on the charcteristics of the engine and the turbo! for exanple, a deisel truck turbo that works at it most effecent at say 100psi would be pointless on a car engine, even a big american V8!

but that doesn't mean it wont work, it will just not be as efective as a turbo designed to operate at the levels you requier! also there is little point on putting a huge turbo that can move 155 million cubic feet of air a min on a mini engine! as its stupid to try and put a Smart turbo on a SBC! its all about horses for courses.

i have seen some US guys talking aobut truck turbos for their V8. anyone know how something like a Garrett GT42 (that's a big frame right????) compares to what you would call a truck turbo???

thanks Chris.

[MrFlibbles]

I remember someone said that they'd never buy a turbo from eBay, as people sold truck turbos and said they were for RX7s or whatever, and it got me thinking as to what the problem would be.

It seems to me like the issue is that a small engine doesnt produce enough exhaust gas to run the compressor, is that correct?

[eliot]

chuntington101 said:

i think it more depends on the charcteristics of the engine and the turbo! for exanple, a deisel truck turbo that works at it most effecent at say 100psi would be pointless on a car engine, even a big american V8! but that doesn't mean it wont work, it will just not be as efective as a turbo designed to operate at the levels you requier! also there is little point on putting a huge turbo that can move 155 million cubic feet of air a min on a mini engine! as its stupid to try and put a Smart turbo on a SBC! its all about horses for courses. i have seen some US guys talking aobut truck turbos for their V8. anyone know how something like a Garrett GT42 (that's a big frame right????) compares to what you would call a truck turbo??? thanks Chris.

GT42 is huge, had the option to purchase one of them when I bought the two GT32's shown above. GT32 is from a 6.6L truck (as in a 40 ton truck - uk terminology)

>> Edited by eliot on Monday 19th December 21:58

[stevieturbo]

You need to decide what sort of boost you intend to run, what sort of airflow thats going to achieve, then find a compressor map suitable to decide which turbo to use.

[chuntington101]

eliot, damm, those things are tiny! Evo guys with 2.3ltr strockers have problems with those things above 500bhp! but then i guess thats still quite a lot of bhp for a deisel!

would you say there are comparable to a GT32 for rough size? they looks similer from the pics!

Chris.