Diseasel turbo.

[tigran]

Would I realistically be able to hold low pressure with a diseasel turb unit?

I know the whole heat issue, but I'm talking like 8psi - would that be realistic?

[slammed 66]

Yes you sure can. The turbo I sold to moomin is a garret gt15 from a rover 220sdi/freelander etc and they run at 17.5psi standard

You'll also get a quicker spool up reaction but may find yourself constantly on boost in motorway situations which is the downside to a small turbo

[slater]

Its hit and miss, blownimp ran a diesel turbo for a bit i think and reported no problems.

I don't think the heat problem will go away from running less boost, its the fact that petrol burns hotter that causes the issue.

[CR500Dom]

As Slater says, its down to Exhaust Gas Temperature rather than Boost

If you have to run a TD Turbo, try to get one of a modern car with a "Diesel particulate filter" as these run much much higher EGT`s, getting up towards 900°c which is Gasoline EGT levels ;D

HTH
Dom

[tigran]

The turbo I am looking at is apparently T3 sized from a toyota diesel so size is not a problem. Guess it's a case of having a go and finding out. At worst it'll give me a good excuse to do a V6 conversion

[lebowski]

As well as the heat issue, diesel turbo's also have different characteristics. For example, the compressor map will be a different shape and you may have problems with choke. When the turbo is running at less than optimum efficiency, the compressed air from it will be heated more, which is a bad thing for power and detonation suppression.





The two compressor maps shown above have the details from my Avenger engine (1.6 8v) plotted onto them. The GT15 at the top is a fairly small turbo and you can see that at high revs the red line goes off the map (on the right). This means that it's running at poor efficiency, which would be heating the inlet air a lot and could cause detonation.

The second map is for a cosworth T3, and you can just about see that the purple line ends inside the 65% efficiency island. This means that at max revs the compressor would be at 65% efficiency, and in the middle of the rev range (where most of the driving is done) I would have around 75% efficiency. Therefore the second compressor is more suitable for my engine.

These compressor maps are both for petrol turbo's, but I was just trying to highlight the point that a mis-sized turbo can cause problems, and a diesel turbo may be even worse in this respect.

You could possibly escape this problem to some extent by using a variable nozzle turbine (ala Blownimp), but personally I would go for a petrol unit.

Hope this helps a bit and I haven't bored you too much.
Cheers

[tigran]

Cool bit of info! The unit i'm getting tbh looks way too big to have come off a diesel, so it might not have the problem that the T15 (bless it) seems to have in the graph.

The reason for the diesel turbo is that to get the same size petrol garrett i would be looking at a huge amount more cash than i can get the diesel for. I'll probably regret it but once the pipework is done i can always upgrade to a petrol turbo at a later date.