short stroke turbo... lots of noobie questions
Turbo Mini Forums

Hi, i'm Dan, bit of a noob to this turbo lark so please be patient. I've done some searching but not really got any definative answers, so just wanted to ask some questions. I've been lurking about, watching a lot of the projects, you got some awsome stuff on this site.

I recently had a 1071s, which i managed to break the other week, and write off the crank, gutted..

..life goes on tho and i'm now sourcing parts to build a new 1071, this time however i'm building it in a standard non-'S' block, so basically i dont have to worry about the heritage and keeping things period anymore, which is kind of a good thing, as i wanted to do something really different.

The thing i loved about the 1071 was the revs, what was annoying a bit tho was it always felt like there was something missing at the top end, it wanted more torque really.

I wanted to ask whats the potential if turbocharge this new one im building? I like the idea of that T2 turbo, where you dont have to modify the bulkhead. Is this the right one to be using?

I'm aware that turbo motors use very different cams to n/a's in that they tend to be high lift short duration, as opposed to the 300-degreers i'm used to. Willl these sorts of cams with the turbo still be able to produce the revs?

Also will the turbo still be able to keep working properly over such a wide rev-range. I can sacrafice a few rev's i suppose if it gives me that massive gain in torque and ultimatly, power, but my old motor used to go to 9k if i let it, so whats the limmits of the turbo in that sence?

I also noticed that a lot of people running turbos are using megajolt or similar, is this a necessity or just preference.

I'll probly have more questions at some point, but at the moment im just trying to get an idea of if it'll work they way i want it to, and whats involved.

Many thanks, Dan

lol, you aswell now eh?

for the turbo without bulkhead mods ether custom mani' or the mirage kit
theres better turbos than the T2 really, a few people are opting for the garrett GT17-52 but im unsure if that bolts direct to the mirage kit
the mega-jolt, its more of a controle thing i believe, with more pressures you want to make sure every spart is occuring at correct time exactly

David.

Hi,
The GT 1752 fits the Mirage manifold but the compressor housing hits the back of the block, you'd also need a custom downpipe.
There's always the T25...
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

As said the T2 is a bit old hat, but on a small bore motor it will allow somewhere near the rpm that you want but will be getting inefficient. A GT series turbo might be a better option, but fitment is an issue with the mirage. Look at the GT20s on the Garret website.

Whatever the turbo, to get the RPM you want you will have to compromise on lowend power to some extent. Cam choice will be crucial to what RPM you can make too. The MG metro cam will probably struggle a bit, maybe a 276 might be a good starting point as it's not too wild.

The will be no dizzy that will be suitable for this type of engine, and for the cost and additional safety I would fit some form of mapped ignition. It will be a minor cost compared to the rest of the build.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

From what you've said it certainly seems possible then, to keep the characteristics of my short stroker, whilst giving them a boost.

With the GT17 and 20 turbo's, should i be paying much attention to the numbers after that? the GT20 on garretts site has many different variations, do they all work the same tho?

I take it with these two turbos, there are no standard manifolds to fit, what are people using then to fit them? Is is considered safe to mig-weld manifolds, or is it strictly a job for a proffesional and a tig welder?

Re-post... skoolboy error

Edited by JetBLICK on 2nd Apr, 2008.

Yes the numbers after the 20 or 17 are important. You need to come up with some theroretical figures to decide which compressor map is most suitable for your engine.

I and others have used the metro manifold to fit a GT17, this requires bulkhead mods though.

A Stainless manifold is really the only other option.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

ok, this is the technical bit then. Is there a 'how to' on this, i've just had a search, but i dont think i found anything, except the bit on how to read compressor maps. I dont really know what i'm looking for tho?

you could try and find the AG bell book: Forced induction performance tuning.

I just read pretty much all of it (i really should get a life) and for me ,my head more accustomed to NA engines, it contained a lot of good and worthwhile info.

Edited by Sir Yun on 7th Apr, 2008.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

There is no how to unfortunately. Look for 'how to read a compressor map' firstly. This will basically tell you that you need to know what psi you plan on running and what amount of air you engine will require at what RPM (this is the tricky bit).

I have some maps with my numbers plotted on it that might help, but I can't find them at the moment.

Edited by wil_h on 7th Apr, 2008.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

You need to calculate your air flow and boost required to meet your horsepower target.

This Garrett site explains how.

Edited by Paul S on 7th Apr, 2008.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Now that was an interesting read, I knew the theory, but have always avoided it as someone kindly calculated them for me. And having stuck in some numbers they match the ones i already have (pretty much).

There are lots of assumptions to make but this should be basic knowledge for all of us i reckon. and I should have known before now!

Fastest 998 mini in the world? 13.05 1/4 mile 106mph