a few unothadox questions
Turbo Mini Forums

hey there, have been a lurker for a while but decided id best find out some information that has not been asked yet (that im aware of).

i drive a normal 998cc stage 1 kit, aldon dizzy, lucas sports coil and thats about it....

i really fancy building a turbo engine for my mini. just so i get to learn the ropes of general engine tinkering with my dad.
im 19 so by now i really should know one thing from another....should!

ive loved the spooling and gush of a turbo since i first heared it. however, i do not see the point in me building a super dupa 0-60 demon because at the end of the day motorways are 70mph and i dont speed (have been driving coming on 2years now) in my mind i know if i made a very nippy engine i would undoubtedly put my foot down more. not too happy about that as i value my liscense.

ive read snowfruits(?) topic asking about 998 vs 1275 vs mety tub tub engines as bases and regardless of what you start off with everyone seems to try and help the best to their abilities and try and get the user the most ponies/boost for their money.

so here comes the really wierd question.

i would like:

a turbo engine, that doesnt freak out when it see's the motorway (doesnt overheat/guzzle fuel).

would like to keep it as low a spec as possible (to avoid moments of sillyness and insurance beatings)

am not overly fussed with boost but dont want to sacrifice lack of boost and make it drive rubish.

i know that metro turbo engines are now as rare as chicken teeth so will probably build off a 1275. however, using a 998 will limit my top speed and power im guessing, will be cheaper to build (seeing as im not trying to squeeze a kazillion psi out of it) AND will have the bonus of the insurance companies giving me a pat on the head for not upsizing...correct?

i would also like to spend as little as possible (duh) as i have a fair bit of welding needing doing. so while that is being done i could get the box put in ready for the engine.

is this do-able? possible? worth it? just want to use it to tootle around to car meets and shows really...
rough total guestimate prices? which block? which turbo? and what is the bare minimum that needs doing to it to enable me to pssst.

thanks everyone,
Pete/Coedy


(and no i wont buy a saber electronic dumpvalve instead :cool:)

Project - 998 turbo

sorry for it being long winded but thought i should try and get all my points across together than all of you having to ask the same old questions...

Project - 998 turbo

if thats the case, why dont you just stick with a std metro turbo spec?

not too crazy and will be reliable.

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

if i could find one id happily jump all over it, unfortunately in the past year ive seen one engine on fleebay, and about 3 cars, but im not willing to tear the guts out of a concours condition metro turbo. plus i couldnt afford the car to begin with...
how much would it cost to make a metro turbo replica engine?

Project - 998 turbo

If I were you I would just bolt a turbo on your standard 998 engine. Get the head chambers enlarged to lower the compression ratio and run 3-4psi boost pressure.

That in my opinion is the cheapest way of achieving what you are after.

Oh! great! so id need a metro turbo unit, manifold, plenulum (sp), carb?

i have a stage 3 head in my garage for my 998 that i removed while i was learning to drive, would that suit the head thing? i think it just has enlarged valves though...
ive got 2 spare 998 heads though so how much does the chamber have to be opened up by?
im guessing it would be best to get the unleaded conversion done the same time. also i read in another topic about competition exhaust valves? would i need these?

finally, t2 or t3? theres a t3 and manifold on ebay at the moment for 115... but ive read in a few other topics that t2s are better for street 998s?

thanks, thats great news!

Edited by Coedy on 11th Aug, 2006.

Project - 998 turbo

Benross is your man for the cylinder head mods, you can send him a PM on here.

A normally aspirated head will not be any use for turbo application, the best thing you can do with that is sell it to fund the turbo parts you need.

For simplicity and the fact it all bolts together, the Metro T3 is a good choice. However is has to be said that a T2 is probably better matched to a 998cc engine. I'd say it all comes down to how prepared you are to do the work of modifying a manifold etc to fit a T2. If this sounds too much for you then just bolt a T3 on to at least get it working.

Apart from the parts you list you will also require a turbo type fuel pressure regulator, and fuel pump.

Finally you will need to sort out the ignition timing, you can either do this by locking the mechanical advance in the dizzy up and running a fixed 25 degrees, or you can convert to MegaJolt. MegaJolt would be a far better solution it has to be said. Alex_F on here can supply the MegaJolt ECU's, I can supply a machined crank pulley and bracket for the crank sensor.

yeah forgot about the regulator and stuff, and ill need a return line yeah? ive heared that a Tpiece between the tank and the fuel pump will be as good as a full return to the actual tank?
or is that a bodge?

ok so once i get a hold of a turbo ill be nagging Benross cheers!
ah, right so i couldnt just get a NA 998 head fiddled to run decently? im sure this Benross fella will be able to point me the right directions anyway.

how much fiddling are we talking about as a 'modification'? big hammer and a hacksaw? or measurements, heat up, bent, weld, etc etc etc.? because if a t2 is more 'favoritable' id rather get that done. do you think any fabrication companies would be willing to do the work for me as long as its explained to me what needs doing of course. that way it wont be bodged (hopefully)

i dont fancy messing about with my dizzy because like i said, its an aldon one. the megajolt junior one i saw on another topic will be ok yeah? something like 130pound? is it? maybe? im really considering that because im hoping it means the rolling road operator will have an easier time. so less time on the rollers. meaning less money outage in the long run!

Project - 998 turbo

What you say is all true Pete, I was just trying to answer his brief in the first post of having a cheap turbo conversion that won't be quick enough to get him into trouble!

The 12G295 head is far superior, but if you are only using very low boost is it worth the outlay?

not sure if its A+ or not, i know its the origional engine so its an '87 and has done a genuine 61k.

my dads spotted a complete metro turbo setup including front brakes in a magazine for £200!!! so will be phoning up about that tomorrow morning, if its still there ill dive on that...

otherwise ill do the lazy t3 and bolt on idea, if it runs dogily ill look at one of those heads. is it a plan people?
(mind you i think id rather keep a 998 just for shiggles and fits)

Project - 998 turbo

ahhhh ok, (yey) and beacuse its an a+ ill have to seriously look into the head then? just realised, would my clutch be ok? annnnd more of a silly question, will a blow off valve still sound nice on such a low boosting engine?

Project - 998 turbo

At such low boost it will probably cope, lets face it you are unlikely to crack more than 80bhp, which is great going for a 998 but won't trouble the clutch or gearbox especially as long as they are in good condition.

Project - 998 turbo

No point just dumping on a head and hoping, you NEED TO GET THE CR DOWN or it WILL NOT WORK.

PM Benross about enlarging head chambers.

Then go and do some reading of old posts to get more understanding of the subject to help you achieve it!

ok, will do, but i thought you said it should be ok on low boost with standard gubbings?

Project - 998 turbo

oh yeah, sorry, my bad. its late.
will pm benross now, thanks again!

if that T3 and manifold are still on fleebay tomorrow morning i will be buying them.
(best off getting the most dificult to source piece first isnt it?)

is there a kit somewhere to rebuild a normal carb into a turbo one? think i saw them on ebay once or twice? or would i be best off purchasing an actual turbo carb?

Project - 998 turbo

carb wise just convert a n/a carb into a turbo carb witht the turbo rebuild kit..... iain on here can get them at a very good price.... imho thats the best way to go, as even a turo carb would probably need a rebuild unless it was nearly new etc.....

And on the 7th day........... God created turbochargers!

awsome, seems like most of the needed bits are available from different people on here! great stuff! just have to find a turbo and manifold now....

Edited by Coedy on 12th Aug, 2006.

Project - 998 turbo