How much boost will a 13c push?

[doingitsideways]

So, I'm having one of my moments of madness, or maybe it'll turn out to be genius, but probably not!

Some of you will know I run a d24tic in my 960. When it comes on boost it pulls reasonably well, but as anyone who's ever driven a d24 will know, the lag is pretty bad!

The standard turbo is a Garrett T3, but seeing a pair of 13c's for sale got me thinking of maybe rigging up a twin turbo manifold.

The thinking is that the two smaller turbos would spool a bit quicker than the one big T3, much like the two tiny turbos on my S80 T6 spool almost instantly, compared to say a T5 running a 15g having a little lag.

So, what's the sort of realistic boost limit of a 13c before they're just a hairdryer?

Also, what's the effect of running two in tandem? I.e am I right in thinking the boost isn't multiplied with a tandem system?

Cheers,

Steve :thumbs_up:

[rogerthechorister]

I have a young fiend who was running up to 12 PSI with an MBC on the standard intercooler on a B200FT. Only problem was clutch slip and I know the clutch was good because I had it done before I gave him the car.

[Steve940estate]

How much do you need ?

Most people suggest that 13-14psi is about as far as you can go but even at standard boost the housings crack.
There are lots of differences between the petrol engines and diesel ones. A diesel won't use such high revs but you do have 6 cylinders worth of exhaust gas to spin the turbo up.
Are diesel exhausts as hot as petrol ones ?

[doingitsideways]

I don't think diesel EGTs get as high as petrols.

To elaborate my thinking; on the standard T3, it starts to come on boost at around 2.5k revs, with a bit of a bang at 3k, but being a diesel it will only rev to 5k absolute limit.

My thinking that the 13s would maybe spool quicker, but then again maybe not as they'll be being driven by 3 cylinders each.

Not sure on boost levels at the minute, but it would be quite high, probably around 14psi, but need to check.

Steve :thumbs_up:

[munday]

Running 15psi through ours at the moment and its a lot of fun.

Stock clutch (probably original) started slipping at around 12psi with the welded diff, so we swapped to a diesel clutch and its fine at 15psi.

Probably going to turn it up a bit more when we have water injection hooked up, the compressor maps look like we can get away with 18psi

[Palmer]

Turn the T3 upto 20 be alreet! ;)

[Steve940estate]

You might need to go smaller or get something designed to spin up quicker. With just 3 cylinders to operate each you effectively have 2 1.2 engines.
A turbo off of a Metro turbo for example might be more suitable.

What about having 2 sizes of turbo, small one for low revs big one for high. I expect this is why car makers fit the variable vane turbos so they can get more bost at low revs.

If you raise the boost on the current turbo you will get more boost sooner so perhaps that worth trying first.

[doingitsideways]

Aye, I had thought about using one of the tiny turbos (12c's?) from my T6 if I upgraded and using that to feed the T3 or maybe something like a 15/16g, but sequential systems get very complicated and without the proper control WILL cause an explosion!!

Perhaps I could take a leaf out of the RS turbo boy's book, a T2/T3 hybrid could work well, the smaller exhaust wheel spinning up quicker??

Oh, I did also contemplate binning the turbo altogether and supercharging it, but then I realised this was lunacy!! :D


Think I'll dig out my MBC and get playing first. ;)

Steve :thumbs_up:

[Palmer]

Adjust the pump as well for low boost fuelling :)

[doingitsideways]

Already done that Chris, I'm just used to the difference it made when I first did it!

Gonna be changing my diff to a taller one soon hopefully, my god it'll feel slow then!! :(

Steve :thumbs_up:

[barkster1971]

make a tubular exhuast manifold for the T3. Then increase the pipework diameter from turbo to throttle body. That will get it spooling a lot easier.
Or port the turbo and manifold you have now.

[averill]

If you wanted to be really clever with a twin turbo set-up, I'd get a little turbo and a big turbo. It would be really easy to set-up the electronics to control it if they were needed.

Try and find the Area/Radius and flow rate of your current turbo, then you'll have a better idea of what turbo's you'll want to put on.

[Palmer]

Already done that Chris, I'm just used to the difference it made when I first did it!

Gonna be changing my diff to a taller one soon hopefully, my god it'll feel slow then!! :(

Steve :thumbs_up:

Ahh bummer!

Tbf sooty used to chip when i nailed the loud pedal but then there was a little delay. But i did increase low fuelling ALOT.

Have you rotated the fuel pin to the steeper ramp? Got rid of that ****ty little white plastic washer at the bottom of the LDA housing assembly below the fuel pin?

:-D

MPG tho brudda! ;)

[TonyS9]

A 13c will boost to 20psi if you want, and any turbo will get generate hot air the more your increase the pressure. Thats what the intercooler is for.

The question is how efficient it is being at your given max airflow and if the inefficiency added temperature is significant.

Noone has taken any comparative temperature measurements that I know of, but going by the stories on here, it would seem above about 200 or 250bhp you will get more power from a bigger turbo, but usually at the expense of lag.

The 13c can run any pressure you want and it does not crack immediately, it takes a few minutes at around 12psi to get too hot from the exhaust. Brief cooling periods are necessary, but this nomally means top speed tests will damage it (but not usually terminally). Drag racing or general fun doesn't seem to cause a problem.

High pressure is normally limited by detonation or pinking, which can be extended by high octane fuel, bigger intercooler or fuel and ignition modifications. For minimal modification with 12psi I would recommend high octane, to avoid the knock sensor backing off the ignition.

[barkster1971]

True but he's wondering how they would get on with a diesel.

[Steve940estate]

You probably wouldn't need the bypass valve if you ran one on a diesel would you ?

[TonyS9]

True but he's wondering how they would get on with a diesel.

Ah missed that bit lol, but I think most of what I said is valid, I was referring mainly to inlet physics. Since the thermal efficiency is higher diesel should give the turbo an easier life from exhaust temp.

[doingitsideways]

Aye, easier on the turbo, presumably how my T3 has managed to survive to 200,000 miles whereas Sierra Cosworths seem to lunch them in less than half that!

But surely lower EGTs would mean slower spooling??

Hmm...

Oh, had a look for my MBC earlier, couldn't find it. Not where I left it. Mrs not moved it. Of course you've not dear!!

Not happy!! :(

Steve :thumbs_up:

[Ade B]

Aye, easier on the turbo, presumably how my T3 has managed to survive to 200,000 miles whereas Sierra Cosworths seem to lunch them in less than half that!

:

Most Cossies are running 300+bhp though!

Just get a T34 .63 on it and deal with the lag :P