bits to get me started??
Turbo Mini Forums

hi all

iv been thinking about doing a 998 turbo in the near fututre.
the thing is...i dont realy know exactly what i need to get to get me started.
iv got a 998 with a stage 1 kit (1.75" maniflow exahst system) ans a modified cylinder head (stage 3) with a 3.44.1 final drive, SO FAR!
it goes very well for a 998.
i was thinking about puting in a sw5 cam.
then i was thinking, after iv done that what should i do?
TURBO came to mind!!!
so what are the things i would need to change/get to make my 998 a turbo? it would need to be reliable/drivable/POWERFULL!
i need to know all the small details as well like whether i need to get differnt pistons, crank, feul tank, etc etc.
and what i need to replace them with etc etc.

any suggestion would be great!

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

read all the posts on turbo engines and have a open cheque book it`s not going to be cheap

1293 Turbo mini

Hi Josh, welcome to the site!

12G295 cooper 998 head - better than any stage 3 small bore non cooper head and 28cc chambers - just right for lowering the compression on a 998.

Are you based in the US? If so then this could be a tricky head to get hold of, but remember that the midget 1098 and sprite MAY have used them as well, but also consider the 12G202 as fitted to all 1098 engines and the cooper 997, they have larger chambers and slightly better ports than the 998 but are inferior to the 295.

Alternatively you could have your current heads chambers increased in volume, this would be the way I would go if you are in the US, I know parts are difficult to come by.

You can also use a 12G940 1275 casting. Others on the site have had considerable success with a 998 in competition with this head so it certainly does work - 140 bannanas out of a 998 is not bad!

The SW5 cam is my personal favourite for 998's, but another good budget cam is the MG metro nat asp one as it has extended timing on the exhaust which should really help.

A metro turbo set up - inlet, carb, ex manifold and oil drain, oil feed will make life easier as well. Converting from the T3 to a T2 would be a good idea as it will boost that much earlier and give more torque but is by no means essential.

A distributor less ignition like megajolt, (see nic's first rate article on this in the FAQ), will provide control over ignition and allow a great deal of advance off boost transforming fuel economy and allowing retard under boost.

This can be done very cheaply!

This would also help out giving room for a front mounted intercooler of a fair size.

Turbo ex downpipe and system available off the shelf. Sounds nice :)

Also budget for a gearbox rebuild, 4 pin diff and an upgraded clutch. Are you verto or non verto? For verto use the turbo set up, cheap and simple.

Fuel pump, pressure regulator, all available of Avonbar worldwide, a good oil pump with increased volume all good ideas.

For setting up, install a Lambda sensor and digital gauge, (digital read outs with numbers are much easier to see than those pretty LED things). This will tell you if you are running lean and prevent melt down.

Finally, get it set up on a rolling road. It amazes me how many people don't bother with this but my 998 st3 picked up 17 bhp with a proper rr tune. Yes it was way out on timing and fueling but you couldn't tell this by driving it, it seemed fine!

Just make sure the bottom end is in good condition and I don't see why you shouldn't be able to run 12 psi on a T3 with a mapped ignition and intercooler.

Shameless plug for Seven Magazine at the end - we have a 998 project car that I am doing the above on - in 24 hours - and dyno testing before and after.

We also have a MJ install, again with before and after dyno plots on a ST3 998 like yours.

One word on gearing, I prefer longer gearing - the ST3 998 pulled 2.95:1 no problems and 7000 rpm meant 60 in second and faster hill times due to less gearchanges, turbo's love high gearing, as Dave said, let the torque do the work :).

I would suggest searching on the subjects touched upon above then come back with what you dont' understand. Must have forgot some parts, but there are the basics.

Good luck with your project!

Peter

Editor

Edited by MAGA7INE on 18th Jan, 2006.

Peter

Editor

MAGA7INE
Seven Magazine
The brand new quality Classic Mini Tech and Journal
Issue 1 out late 2027.

hi
cheers for the reply mate
im in ENGLAND by the way ill put it in my profile!
can you still get hold of 998 cooper heads and are they the best to use?
when i come to tune it i will take it to peter baldwin as im not that far from his rr!
what size exahst would you recomend, at the moment i have a nice maniflow system (1.75" stright through single box system, wiv a freeflow minifold and alloy inlet minifold)
also im thinking of getting a lightend road flywheel from minispares, would this be ok to use as it says that the the clutch plate that comes with it has more pressure than the turbo type....hers a link

http://www.minispares.com/Product.aspx?pid=37371

would it work?

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

Hi Josh, for some reason I thought you were from the states, doh!

OK much simpler then. I would use the 12G295 cooper 998 head, also used on the 1098 MG midget engines. This is as far as I am concerned the head of choice for a street driven turbo 998. Also means you don't have to machine the block as you would on a 12G940 1275 head.

Ebay - there are always 12G's for sale on ebay. The 12G flows more stock than any 998 head ever will, though if you have a lot invested in the head and it's unleaded then get the chambers opened out.

Morspeed, avonbar and the exellent VMAX scart as well also do them.

Sell your current exhaust, inlet etc on ebay or similar, it's no good for the turbo conversion. Minispares and others sell a 2" downpipe and single box 2" system. You need to use the turbo inlet and carb.

Turbo's like minimal back pressure so stick with the parts that fit easily.

You will need to modify the ex clamp for the 2" pipe by grinding a bit of it. Not hard, but if you don't do this it won't seal properly and you will have leaks etc all the time without knowing why, now you do!

Of course there is the bulkhead box to weld in as well for clearance.

If you are going to invest that sort of money on a flywheel, then just convert to a pre verto set up. Verto's it's said, (about to find out!), are limited to 115 ft lbs of torque before they slip, which may be OK for a 998 or it may not. I would just use the verto turbo set up for now and save a bit. Do a search on this subject, far more has been written.

Super cool 2 core should be on your list as well :)

Hope this helps

Peter

Peter

Editor

MAGA7INE
Seven Magazine
The brand new quality Classic Mini Tech and Journal
Issue 1 out late 2027.

ok ill look into it all mate
i just needed a starting point if u know what i mean
the thing that will get me at this piont is insurance (as im only eighten) but im going to research it all and get my mini as good as posible (make it look good in and out, handle good etc) then ill find out what the insurence will be wiv a midly tuned 998 turbo.
just another question....does any1 have a 998 turbo that they drive everyday? if so how reliable is it and how much power is it producing?

cheers
josh

Edited by JT on 19th Jan, 2006.

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

Peter

Editor

MAGA7INE
Seven Magazine
The brand new quality Classic Mini Tech and Journal
Issue 1 out late 2027.

ok maga7ine cheers for all your help mate
im looking into the turbo conversion now so i have as much 'know how' for when i come to do my conversion!!
for know im going to leave the engine as it as it is as it is quick enough for me for now wiv the cylinder head and stage 1 kit.
like i say im going to do the suspension etc as it should not do much to my insurance (hopfully)
when do u think i should be insurable on a 998 turbo and other mods like suspension roll cage etc? 21 years old?
i carnt fucking wait!!!!!!!!!

good luck with your project. ill definatly want to know how it goes once uv done it. are you using the spec u lited above?
also just a few things i want to figure out....
what oil cooler to use?
will i need to get a differnt feul tank? if so what type MPI?

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

You don't need an oil cooler.

Yes, the MPi tank is ideal, minisport still sell them for £100, but check it is an MPi not SPi tank, MPi has a higher pressure pump apparently.

At least you are doing it the right way around, with a sound car with sorted suspension. Also try using EBC greenstuff pads, they make a huge difference to the brakes, far more than converting to metty 4 pots.

Have a chat with HIC, they should be able to tell you about insurance.

My motor is going to be a test of the structural properties (!) of a stock 998 bottom end and a pile of boost pressure so apart from the head and Megajolt, it will be stock internally. More to come later though :)

Peter

Editor

MAGA7INE
Seven Magazine
The brand new quality Classic Mini Tech and Journal
Issue 1 out late 2027.

yer iv got green stuff pads for my minispares 4 pot calipers (7.5" discs).
are you sure i wont need a oil cooler? wont it get a bit hot? or is a oil cooler only needed on big bore turbos?
also will i need to get a differnt crank pistons etc? or r the standed 1s ok as long as there in tip top condition?

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

No one who has logged oil temps has reached temperatures that justify one, not even on the track. The A series has a large reserve of oil.

This obsession came from the days where old technology mineral oils would break down badly if they went over a certain temp.

Maybe on a road car a new MG metro type oil cooler that is plumbed into the water cooling system is a good idea, getting the temps up from cold very quickly and limiting higher temps.

If you use a temp gauge and find that there is a problem, then at least use a thermostatic one. Low oil temps are if anything worse for the A series than high oil temps.

If you go for a T2 later and plumb the water cooled centre bearing in I would think that would also help.

It is more important to make sure the cooling system is in tip top shape using a 2 core supercool rad than to mess about with oil coolers and to fit an efficient intercooler and properly set up the car on the rolling road.

I will be monitoring the oil temps on the 998 and will post them in an old oil cooler thread.

The 998 is a very strong engine though if you start spending that sort of money on full on rebuilds then you will get a lot more power for your money with a 1293 or 1380 TBH. I am doing it so as to stay in the up to 1400cc class in hill climbing and because I just want to do it.

If you build a mild 998 turbo and wait for your insurance to come down then you should be able to reuse all the parts on a larger engine. You are never going to equal GF or Miniwillliams 13 sec 1/4's with a 998. Well you might, but it's going to cost you!

I think a stock 998 bottom end should cope with 12 psi with an intercooler and mapped ignition. But we will see with my engine.

Peter

Editor

MAGA7INE
Seven Magazine
The brand new quality Classic Mini Tech and Journal
Issue 1 out late 2027.

i could get a quote of around £650 from adrian flux when i was 19 on a 1275 turbo, that was with points and a claim too

yer that sounds very good
i mite just go down the bigger bore route with a turbo as it will be more reliable and quicker! i would have it as a middly tuned chav killer but for everyday use aswell.
what ever i do i will start to build the engine/get bits for the engine when im 19 (next year).
but before i will get quotes etc. hopefully i will be able to keep the classic insurance as i have at the moment which keeps it down alot!!
if i was to go down the 1293 or similar route will i use the same as the above list apart from the cylinder heads etc also would it be better to use a t3 instead of the t2 turbo or is the t2 best?

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

a big bore block will prove easier to aquire parts like pistons

its horses for courses as far as t2 or t3, but personally id go t2 as it comes in lower in the revs making it more drivable, thus more fun (in my opinion)

hox much is a t2?
were can i get 1 from? what car are they on or were can i buy 1?
are the metro turbo engines hard to come by? or is there loads of them?

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

renault 5 gt turbos are the ones to have, you can get one from £50 secondhand to £350 ish new, you will also need an adaptor from jimster if you want to use the std turbo manifold. Or you can use a mirage manifold, which will also mean that you dont need to cut the bulkhead

metro turbo engines are getting hard to come buy for sensible money, if you plan to rebuild you can use any 1275 block, but a turbo crank would be a good idea cam 6581 (i think) is the casting number

if you dont get a complete turbo unit you will need to find
turbo carb*
plenum*
inlet manifold*
exhaust manifold*
distributor*
fuel regulator
fuel pump
oil feed
oil cooler


*these can be harder to find/or expensive

this is what i think i need:

1275 engine
feul pump
feul regulator
T2 turbo
turbo oil feed
mpi feul tank
oil cooler (what type/size)
mirage manifold (is that the inlet manifold??)
2" turbo exahst system
crank
phase 2 cam

what about mega jolt or mega squirt?
would i use these instead of the distibuter? or am i compleatly wrong??
is there any good head mods to do or is that the same as a N/A engine?
also any good options for a final drive and gearbox to use etc?
rember, this will be for a everyday fast road car!

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

oh you will also want to change your pistons to some turbo ones to get the compression ratio down

the mirage manifold is an exhaust manifold, read this http://www.turbominis.co.uk/forums/index.php?p=vt&tid=5742

you can use the megajolt instead of a distributor it is well worth doing considering that it doesnt cost much more than a new distribtor

you should also fit straight cut drop gears as a must, consideration to fitting a straight cut box, a minispares 4pin diff is a very wise move

a final drive of 3.2 or 2.9 for road use,3.44 if your planning some track work


oops just read what peter was saying about the oil cooler-it might not be needed then

a 998 turbo would be very interesting though...

yer im in 2 minds realy wheaver to do a road going 998 or just do a 1275 turbo
im just gonna make a list of everything i need to do for both then deside what im goin to do nearer the time.
could i use a 3.44.1 final drive for road use (i am using one at the moment and its ideal for what i use it for!) or will a turbo be a bit differnt?
i think i will try and save up for a stright cut gearbox as i think they sound very nice and help deliver the power to the road!

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985