My 998 turbo project
Turbo Mini Forums

Thanks for the info guys, had alot to think about with this project and so ive had a rethink of the spec of my engine. Could you uys have a look and see what you all think please as i now have my engine and wanting to get started once this snow has gone.

Engine spec:
Chemical cleaned block
60+ overbore and hone
(Pocket the block if i get a 1275 head)
Hepeolite dished pistons (Giving 8.3 - 1 on standard head)
Nitrocarbonised + wedged crank
Polished conrods
Lightened flywheel
Lightened back plate
Race / rally clutch plate
Orange diaphragm
Kent 276 cam
Lightened vernier duplex timing gear and chain
Polished and ported 12G295 head (Unless i can get hold of a 1275 head)
HIFF44 Carb
T2 turbo running 7psi boost (min)
Megajolt ignition
High pressure fuel pump
Fuel pressure regulator
Air intake pipework
Oil cooler
Braided oil feed pipe
Dump valve
Intercoole
4-pin dif
Hi-capacity water and oil pump

Is there anything ive forgotten?


With respect of the above cam choice can anyone tell me what would be a better choice of cam as ive heard alot of different info but no one has specified what cam would be best???

Would the swiftune sw-05 be a better choice and has anyone tried minisports own cams???

You could get away with a higher compression ratio, provide you have a decent intercooler. I would not go any lower than 9:1.

Standard crank and rods are plenty good enough for the job.

Kent 276 is a bit too much. 266 or the MG Metro cam may be better. There is no such thing as "best" as no one has done any back to back testing.

You don't need the 12G940 head unless you are looking to run high revs. IMHO.

What is your HP target?

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."

So could i get away with a standard 998 head or would i need to change it for a 295 head. If i can get around 100hp i would be very happy. Is this setup going to give me a reliable engine?

I'm using a 12G295 head at 12 psi and have 112hp.

I would suggest that you look for an unskimmed 12G295 head on ebay and use that with flat topped pistons. If that is not forthcoming use a skimmed one with dished pistons.

Reliability depends on your right foot. Week points are the standard gearbox and drops.

Also standard pistons should be avoided. Flat topped drilled Hypatecs (P20950) or dished P20773s would be the best options. Avoid Hypatecs with slots.

This is based on my own experience but there are other ways of doing it.

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."

Has anyone tried using a standard 998 head and if so was it any good?

Alpa had a modified 998 A+ head, but put a 12G295 at the top of his shopping list.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=222687

Edited by Paul S on 10th Jan, 2010.

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."

A standard cam and 998 head will be very restrictive. And putting a 276 or 266 with a standard head will not work NA so I doubt that it will be good with a turbo. It would be interesting to see what could be got from a standard head, but I would hold out for a 295.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

Picking up a unmodded 295 head next month so that bits sorted now.

Yes forget the std 998, it's a crap. When you look at a 295 head you understand where the difference comes from.
I'm going with std 295, 266cam, RHF4 turbo, 1bar/14psi, std pistons, we'll see.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm