'96 940 CD HPT estate - MBC questions

[Steve940estate]

I've only got the standard turbo so thats why I don't know what boost cut is. Blowing hot air into the engine isnt the only problem. More boost means a lot hotter turbo. The standard housings are quite often cracked and so are the exhaust manifolds and the extra heat will make them worse quicker.

Thinking about it the most noticable thing when driving normally is the fact you don't have to change down so often.

[mikkey850]

Thanks for the info guys.

I wouldn't mind possibly fitting a bigger turbo in the long run but that depends on price. And how hard it is to "clock" a FWD one to fit RWD.

regards.

Michael.

[munday]

You WILL hit fuel cut. There are differences in how it works as you get to the later years. A 96 will not have the seperate unit you can unplug, so requires a chip, ostrich, or zener diode.

All this talk of a 13c pushing hot air etc etc. I am measuring pre TB temperatures at all times as well as AFRs and boost levels, so I have data to back up any conclusions I come to. 15psi and the 13c is loving it, will be bumping it up to 18-20psi with water injection soon

The stock intercooler holds up fine to 15psi, I wouldn't worry

Steve: Yeah pretty standard, got an ostrich but only using it to trim cold start fuelling and remove fuel cut really for now. Also decat and custom 2.5" system with stock backbox.

[Steve940estate]

Sounds like I have quite a bit in reserve then. I'm not too worried as I can't afford it going bang.

[mikkey850]

Thanks for the info guys I dont want any more than 14psi, what psi does fuel cut hit? Or will I have to learn the hard way come my birthday!

[munday]

Originally Posted by mikkey850

Thanks for the info guys I dont want any more than 14psi, what psi does fuel cut hit? Or will I have to learn the hard way come my birthday!

Will be slightly different car to car, 14psi may reach it. You'll have to suck it and see. You'll soon know when you hit it!

[barkster1971]

Go from a 13c to a conical flanged 15g and you'll love it even more. The temps may be ok at 14psi but the turbo hotside will crack eventually, might be tomorrow might be in a few months. That would be a good time to then stick a slightly bigger turbo on and a better cam.

[TonyS9]

Munday, what does TB mean? And what are the Max temps, I'd love to see a comparison between 13c and 15g for same pressure.

The 13c is prone to cracking but only if you sustain high boost for too long. You should keep it wot less than 30s, then have the same cooling period at say 50%. Its not good for racing other than drag. A 15g seems stronger, or the heat is just less concentrated. I am yet to be convinced of the higher efficiency.

High octane also helps reduce temps.

[munday]

Originally Posted by barkster1971

Go from a 13c to a conical flanged 15g and you'll love it even more. The temps may be ok at 14psi but the turbo hotside will crack eventually, might be tomorrow might be in a few months. That would be a good time to then stick a slightly bigger turbo on and a better cam.

Yeah we arent worried about turbo life, will upgrade when the time is right

Originally Posted by TonyS9

Munday, what does TB mean? And what are the Max temps, I'd love to see a comparison between 13c and 15g for same pressure.

The 13c is prone to cracking but only if you sustain high boost for too long. You should keep it wot less than 30s, then have the same cooling period at say 50%. Its not good for racing other than drag. A 15g seems stronger, or the heat is just less concentrated. I am yet to be convinced of the higher efficiency.

High octane also helps reduce temps.

TB = Throttle body

This one has been built for drifting and general lugging of 3 peoples crap when it needs it. Its a pool car basically, just with lots of boost, a welded diff and cut springs.

Higher octane will not necessarily reduce exh gas temps. The calorific value is not significantly different, therefore at the same lambda you have very similar mass flow of fuel which is where any temperature reduction would come from. The only potential mechanism for reduced temps is if the lower RON fuel is severely spark retarded due to knock, however the ~3 degree spark timing difference you'll get from 95 to 98RON fuel will have negligible impact.

Now if you get hold of some E100 and chuck that in there, no more worried about detonation OR temperatures....but be prepared to run 7.5-8:1 AFRs

[rogerthechorister]

Should we mention water injection at this point?