WANTED 998 J SERIES CYLINDER HEADS
Turbo Mini Forums

I don't know about the J series heads but I have fitted a couple of 12G295s to otherwise standard engines and the results are very impressive.

The point here is that the standard 998 head is very restrictive and any changes reap huge rewards.

I fitted 12G295s to both Stugeo's Racing Flame and Axel's 30 together with an LCB, Maniflow exhaust and HIF38 an a MG Metro manifold.

The horspeower increase must be in the region of 30-40%. We obviously have not rolling road tested them.

I reckon half the increase in down to the 12G295 head. The inlet ports are much bigger and the open chamber head design aid flow. Whereas they used to run out of breath above 4500rpm, they now rev happily to 6000.

Vizard claimed around a 20% increase in horsepower due to the 12G295 alone.

Hence I accept the possibilty that the J series head will provide the gains claimed.

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."

20% of 39bhp is a little under 8bhp, which is what I'd expect a 295 to give. I can't see a small mod to a 998 head giving the same.

What I accept is that the maginal gains these heads may off is important when only staoc items can be used.

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

I think we need to know more about the engines before we can really coment and we clearly don't.

Everything being equal, cr, cam, exhaust, etc, I am personally very supprised that you see these gains with these heads. However, you are so there you go.

And please don't get angry about sceptics, we have all seen many people on the net claim rediculous things with no backup data, why should we trust a sentence on a thread?

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.

What cars where these j series heads fitted to? any ideas of models and years?

Team Racing

surely in autograss driver skill on the dodgy terrain is worth more than even 8 bhp, surely class 1 allows for a basic stage one setup???? seems a bit of a splash on ya boots in the wind can you not use a 202 head?

its myth despite what they say, we all know theres no proof without pics on the net LOL

i'm just joshing! P

SKYLINES ARE LIKE CLITS, EVERY FLANGE SEEMS TO HAVE ONE: see this sticker on my silvia

the Search-section on this forum is blummin superb & simple to use, unlike some other forums, without the search-section & the help of this bunch of chaps on here i'll never be able to !!!Start the day with a 998cc turbo!!! :) i'm getting closer though!

Tom Fenton says: I have it all, make me an offer

Power is everthing in class 1, if you are not at the front on the 1st corner,you will find it hard to win!!, class 1 engine running j head are 39 to 46bhp on the rolling road and have be tested and proofed by DNG and NGRE

Edited by kal14 on 14th Jan, 2010.

But what were the engines on those rollers with a standard head? you need both figures to prove any gain IMO.

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

All things being equal, a head with shallower guide boss must do better than one with proeminent ones.

8 to 19% (8/42) seems quite a lot to me but hey, the guy wants to buy, not sell ...

Rusty by nature