Small Bore Project
Turbo Mini Forums

Ok I have been doing a great deal of reading the last few days. I’m toying with the idea of a turbo engine in my car. So I thought I would start a bit of a project thread so I can firm up a spec to allow for an idea of budget and make sure I’m understanding everything…

My Car
To help out in I thought it would be a good idea to give a bit of background on the car and me, this seemed to help in other posts that I have read.
I have a Mk2 998 low CR with a 12g295 skimmed 80 thou and twin 1.25 SU’s. We have converted the brakes to use Fiesta callipers and 7.9” discs as I want to stay on 10” wheels. The car is very original and I have had it for 15years but it has sat in my mum’s garage most of those years. I got it out about 18 months ago and started doing it back up. I can’t bring myself to sell, and I wouldn’t get enough for it to make a bike engine monster it but would like more fun at the weekends. I have undertaken the above mods to help the car keep up with traffic and stop like a modern car but now I want more fun…..
So I was thinking of a turbo option.

The low CR has been a bit of a bugger with the power on the current engine so I thought I could use it to my advantage. With these things in mind I have started to research the small bore turbo route.

Why Small Bore
I have bought a second low CR engine, with a remote change gearbox as I don’t want to mod the car shell I will keep the old engine so I can drop it back it. I like the idea of a street sleeper and the small bore seems fitting for the car. I have the 295 and my current engine is running 9.0:1 as worked out by Simon at Morespeed who I got the head from.
I also have a set of 1098 rods, pistons, and crank and I do like the idea of a 1098. I have been reading the thread on here.

What I want from an engine
I don’t like screamers so the low end 1098 does appeal to me. I’m not wanting all out power but something that is pacy, so from what I have read about 7-10 psi??


So what to do
Ok I have started some research and split it up into the following:

Engine Block
- Ok I love the idea of the ford crown jets and want to give this a go. Seems a very good idea
- I’m not sure what state the block is in so I will need to strip it down. But I have read most people re-bore is this because you need new pistons as the existing dished ones are not up to it, or because the state of the block?
- Going to run with the metro cam + new bearings.
- Going to use my 295 and looking for about the same CR as I have now.
- New water pump and oil pump
- Main strap seems sensible esp on the 1098 route?
- Duplex timing gear but I'm not sure on what yet.

Carb
- Looks like a hiff44 but I need the turbo one.
- Going to need a good pump and regulator

Mainfold - Turbo
- Going to have to stick with mirage so I don’t body mod
- T2 Turbo

Intercooler
- mmm not sure here I would like a neat install but It looks difficult with a std round nose I would Like to keep it a bit retro, maybe black piping would help?


Ignition
- Know idea here ..I would like to stick with a dizzy as I’m +earth but I understand this is a compromise…..

Gearbox
- Going to get the current one rebuilt new bearing etc, and add a 4 pin diff.
- Leave the std drops
- Clutch not sure… I have a new std one but reading this site it might not be up to the job.


So anyway am I going down the right route?????

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Here is how the engine is now

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Your spec is much the same as mine, so I would have to say that OK. However, a couple of points:

I would question any benefit from the under crown jets at this sort of power level. Good engineering, but is it realy necessary?

Even though you're +ve earth, it should still be possible to run mejajolt which would be much better than a dizzy. Not sure how the coil pack will work with +ve earth though.

The other improvement that we are all struggling with is finding a replacement for the T2, but given the choice of manifolds, best stick with it for now.

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."

Also.

Full marks for doing the research properly.

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."

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

to use dished pistons is a good thing so that does not matter as long as you are able to get the correct dish size.

Edited by gr4h4m on 19th Jun, 2007.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I rebored because of the block and it meant I could used the Minispares flat topped 20950 pistons with my unskimmed 12G295 head.

As you need to stay with dished pistons, I would suggest using 20773 pistons. They are readily available and cheap as well as being well proven at boost by Wil & Ben H.

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."

Paul S what plugs are you using? oh and what thermo stat in your 998?

I have got myself an SC12 charger and a set of manifolds from AUS. going to bolt it to my existing engine whilst a build a new 998 next year

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Hi,
Should be dead easy to swap it to negative earth. Just "flash" the dynamo and you're done
Then you can have a radio too!
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

????

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I was talking about spark plugs... or are you reading my mind about a new ignition system :o)

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Hi,
If you're talking to me, yes.
MJ install, turbo fuel pump or anything else modern you want to fit will be neg earth.
If you re-polarise the dynamo and turn the battery round you'll have a negative earth car. It won't rust as fast either
Cheers,
Gavin :)

Edited by Bat on 17th Nov, 2007.

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

Hi,
That'll work Rob, if you want to retain the "original" look.
However with a coil pack, it won't grind to a halt in heavy rain:)
I've ran mine in storms where the car filled up with water, but it got me home on 4 cylinders
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

hi all what spark plugs do you use in the turbo cars, and what thermostat?

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

In my hilclimber (15psi 150 bananas) I use NGK BPR8ES, in the road car I currently have Champion RN7YCC, the NGK equivalent is BPR7E I think.

For 7 to 10 psi the 7s will be fine

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

www.twin-turbo.co.uk

thanks

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

well I have got my Sc kit from Ausand MR BENROSS worked some magic on my head.... so looking to make some headway over the xmas break..

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

That manifold looks gorgeous, do you have any more info on it?

Yep its made by an AUS mini forum member. to fit the Toyota SC12 supercharger. Its been ceramic coated looks great... With the good exchange rate the kit was good value.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Mocked up the manifolds on the bench..

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

well hadn't done much for months been working on my mums house.. had a couple of days in the garage and a mate popped over to help looks like this now. Just a few jobs to sort.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

looking good, very tidy 8)

thanks it needs a bit of a clean but its getting there.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!