998 turbo build
Turbo Mini Forums

Hi,
Im planning on going down the route of forced induction for my 998 A+ engine and im in the process of collecting the bits i need and i just want to make sure that my planned spec would be ok and if im forgetting any parts i need.

So
The parts i have
-12G295 head - unskimmed with standard valves.
-MG Metro cam
-metro turbo carb and manifold
-Metro Turbo exhaust manifold - not sure will i stick with this or go with a custom one, dont fancy cutting the bulkhead.

The parts i need
-megajolt setup
-T2 turbo
-Intercooler
-diff - ive head the diff is a weak link, any ideas what kind

I actually have a metro turbo dizzy so if that would work well, imight use it.
I might stick with the standard pistons if the cyclinders and pistons are ok but wouldnt mind boaring it out a bit a fitting new pistons that might handle the power a bit better, depends on costs.
Im probally missing loads thats most of the bits, i hope.

Im a complete novice when it comes to engines and ive never actually rebuilt an engine so its going to be a big challenge. Ive spent many late nights reading up on this but i still have loads to learn.

I want this as reliable as possible so any advice on any bits that would help reliability.
Any ideas what sort of power i could get out of this spec and what an ideal boost would be. Dont exactly know what cr i would get but it should be about 9.1:1 but will do proper calculations when i do a trial build of the engine.

Will the standard valves be ok in the 12g295 or would it be better to go bigger.

Any advice or links on suitable parts would be great.

A job worth doing is a job worth over doing

Oh ya, i have a metro turbo fuel regulator and fuel pump too.

A job worth doing is a job worth over doing

Why not go 1275cc?

Why megajolt?

Why intercooler?

If you run high boost to need an intercooler, your'l need to upgrade lots of other parts.

Edited by Brett on 16th Jul, 2011.

Yes i moved to the darkside

Instagram @jdm_brett

mj yes, it helps and runs better from what ive seen, e.g. start up and no run on plus you can map it to your build.

intercooler will help any turbo build. (very easy to do)

good head will get you a long way, ben or phil are the wizards.

if your looking to push it past the limits of a standard mg turbo eg gearbox drops, then you may need to upgrade tthat lot.

diff, not sure, but thats what puts the power out of the engine, with driving skills of mine, ive smashed two in the mondeo lol

Not sure what you are saying here. are you suggesting that there is no need for an IC or MJ?

Couldn't be More wrong, even at 5psi, an IC will be of benefit, and MJ is an absolute MUST on any 998 turbo build because there is no suitable dizzy. In fact there is not a dizzy in the world that is any good for any application!

And what is this high boost you talk about? I run 180bhp on stock bottom end.

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

www.twin-turbo.co.uk

Now to answer the original question. You seem to have a good handle on the requirements.

Pistons are the sticking point. I have found that the MiniSpared Mega pistons are very good. But these are NLA, I have not tried the replacement they are now stocking.

You could try the Minisport Aus pistons as these are the same as the Megas as I understand it. But they don't make the flat tops ones MS stocked as far as i can tell.

http://www.minisport.com.au/category5_1.htm

These might be the MS new piston, but it's not clear http://www.minispares.com/Product.aspx?ty=...id=38687&title=

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

www.twin-turbo.co.uk

that one you linked to is most probably a graham russel piston. They where called Evo before at least. Also they are described as having a high silicone content, as are these.

If so I would feel quite confident with using those.

Any ideas what sort of bhp i could get at say 10psi with the bits i have and as for the T2, what make/madel car could i get one of these from, or is there a different turbo that might suit better.
What about the valves, is there need to go bigger, and is there any possibility that i could cut into a waterway or oil way if i was to fit bigger valves and unleaded valve seats.

i gave a look at the link for the pistons (http://www.minisport.com.au/category5_1.htm) but from what i can make out they only sell 998 flat tops at +80 bore. Is boaring the engine out a good idea or is there need.

Will probally go with a megajolt, where would be a good place to buy it cheap.

I dont really know why i want to go with a 998 over a 1275. I just like the idea of a small bore turbo, something different i supose, and plus i already have a 998 engine, and i could always go with a 1275 down the line if im not impressed with the 998 as most of the bits should be the same as the 998.
Insurance is another thing, dont know exactly how much it would cost but its surely cheaper than a 1275 turbo. Im living in ireland so insuring a car with a modified engine could be tricky. im only 21 so cant get classic insurance, any ideas hom much insurance would cost in one of these.

Sorry for all the questions, just want to make sure i know what im doing an what bits i need to get.

A job worth doing is a job worth over doing

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."

would these pistons be ok so,
http://www.minispares.com/Product.aspx?ty=...id=38687&title=

And as for valves, 214 valves mean nothing to me, ha. you will have to break it down to lay mans terms, are they stainless steel. and what size are they, did you fit unleaded valve seats.

The thing about using a turbo from a renault 5 is that they arent that popular in the scrapyards around me, is there any other more common car that would have one of a simular spec.

A job worth doing is a job worth over doing

Yes the 20950, but these are no longer made by the same firm as the ones I have, but they may be the same spec. I did ask but wasn't 100% on the answer.

10psi will get you between 90 and 100 bananas with a 295 head.

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

www.twin-turbo.co.uk

Those are the correct pistons, part no P20950-20.

For valves I use C-AEG587 and C-AEG588.

TurboPhil on here can fit unleaded seats.

Try ebay for the turbo, but be careful.

http://cgi.ebay.co.uk/Renault-5-gt-turbo-T...=item19c72d2c51

There are other turbos but take some work to adapt.

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."

It's well worth swopping out the standard ex valves for the stainless items, the standard ones are monkey metal & usually well worn out.
You'll also find that if the head's seen any kind of use the exhaust seats will be sunk. Going to an oversize valve will allow you to cut a decent fresh seat.

WWW.TURBO-MINI.COM

Its actually the other way round in the head i have, the inlet valves seem to be sunk lower than the exhaust valves, but i will probally get unleaded valve seats fitted anyway so should sort out all that, the valves in it were changed at some point i think but dont know if the exhausts are stainless or not, where would the best place to get these be. is there any need fitting bigger valves.

A job worth doing is a job worth over doing

It's possible the ex valves may have already been swopped for larger ones then, as I've never ever seen a head where the valves were standard sizes & inlets were sunk more than the ex
Have a measure & see what you've got fitted.
Minispares sell an oversize 26.5mm ex valve for the 295 head. The other option is to use a 29.4mm ex for the 1275 heads, though this is longer so the springs heights need correcting.

Edited by Turbo Phil on 16th Jul, 2011.

WWW.TURBO-MINI.COM

i just took them out and measured them roughly with a ruler, the exhausts are 25.5mm and the inlets are 31mm.
i opened a topic about this on the mini fourm as i was a bit worried that there was something wrong. There a few pictures of how the valves sit on it.

http://www.theminiforum.co.uk/forums/index...t=#entry2128218

A job worth doing is a job worth over doing

They're standard valve sizes then. Looking at your pictures the ex look very pitted so by the time they're recut you may need to up the valve size really, or you could fit an unleaded insert & retain the standard size ex. It's hard to make a proper assesment from a picture though ....

WWW.TURBO-MINI.COM

ya, i know what you mean, ill see how much fitting the unleaded valves seats in are and go from there, but the bottom line is im better off changing them to stainless ones no matter what size i choose, as for the inlets, will the standard size do or would i be better off going a bit bigger too.

A job worth doing is a job worth over doing

[quote=wil_h,16th Jul, 2011]Not sure what you are saying here. are you suggesting that there is no need for an IC or MJ?

I'm not saying there is no need for them, its just from the original post, it appears that this guys on a tight budget.

It is possible to run safely with dizzy and without an intercooler at low boost levels, so I was just asking the question.

As you have said on other posts, decide what your going to use the car for before building it.
I think in this case, i'd get the insurance quote, before purchasing the parts.

Good luck, whatever you do

You can get a series 2 escort turbo IC for £15 and some hoses off ebay/scrapyad for a tenner (well I did).

Having tried using a fixed dizzy, it's not worth it. If you are limited with funds, this is not the place to scrimp. It will improve, safety (of running boost), reliability, and drivabiility.

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

www.twin-turbo.co.uk

and MJ is likly pay for itself in fuel economy fairly quickly.

if your on a tight budget then personally i wouldnt even think of a mjlt .

,what you get from a mjlt is better economy ,better off boost power and generally a better curve of power .

what you get from points , is cheapness , if you get the compression down to around 8.5:1 you can run say fixed 24 degrees timing ,and with the vacuum advance working get some advance above that at part throttle .

this will work ok everywhere ,just not be perfect ,but will cut your costs and get you on the rd .

a mjlt can allways be fitted later ,

remember ,turbo engines have been running with fixed timing for a long time before mjlt came along ,and personally i have run 3 different engines with fixed timing ,making 135 bhp from 498cc in one case .

intercooler wise ,the lower the boost you run ,the less effect it will have on the power .anything les than 7 psi is a bit border line for the gains i feel , and again ,this can always be fitted later .

all just in my opinion of course :)


regards
robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Trust me. If you run 7psi on a 998 you will be a bit dissapointed, and will want more boost soon.

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

www.twin-turbo.co.uk

Wel i have a metro turbo dizzy already but will probally go with a megajolt setup if i can get it cheap enough. the edis bits shouldnt cost a whole pile. And i would rather it run better and more reliable for the extra few euro.

Any ideas where i could get one,

i was actually talking to a fella the last day that has a megajolt v3 for sale but its missing some part of the vacume sensing part of the circuit board, he recon they can be got easily,

can these parts be bought. By the sounds of it he just wants it gone so wouldnt cost too much.

But are they easy enough to work with, like i said earlier, im completely new to messing around with engines and minis too so would it be alot of hassle getting it setup right. Can you get maps already made up or do you have to start from scratch.

The worst thing is i was checking out insurance last night on the net, and i cant get classic insurance, so i thought i could get the father to insure it and i go under him but it turns out the named driver has to be 25 or over, if i was to get open insurance would i be covered to drive the mini if my father was the only one insured on it.
They dont like modified cars in ireland so even getting regular insurance would be a struggle but i should be able to get it,
Their must be some way of getting around it,

Ill have to ring around in the morning and see whats the story, I dont plan on driving it every day but still want to be insured properly.

A job worth doing is a job worth over doing