turbo 850?
Turbo Mini Forums

Easy issues to overcome. I'm working on getting my 850 turbo'd. Should be done by the middle of this year I think, maybe a little after. As for pistons, Crower, in California, will do up some custom's for $160(U.S.) a piston. I think if you're going for low boost, and just a basic commuter, then the gt15 would be perfect, personally I'm going to use a gt17. Crower will also do the crank and rods. And the cam, if you've got the motor out, take it to tha machine shop, and have them machine the block for 998 cam bearings, problem solved.

850 cranks, fully prepared can go to 9000rpm according to Viz.

This is mine, lightened and nitro-carburised:


Not exactly coat hanger, but not as chunky as the 998/1275 varieties.

Other potential issues with cutting 4mm off the block are pushrod length and the water pump pulley will hit the head :(

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."

Miniswordsman keep me posted on the build it will be interesting to se the results, i cant see mine being done before summer but we shall see.

What sort of power are you looking for?

I was going to get the block machine for the cam bearing, get the crank hardened etc, but i think i may have to conced and bore out the 850 to fit slightly biger piston as i cant afford to spend too much on this build. Hell i need to get the car MOT'ed and on the road first!!
mike.


Paul - how much did it cost to get that done too your crank??
and why did you shave 4mm of the block - are you going for a shortened stroke 998?

Edited by richardsoniscool on 19th Jan, 2010.

1978 - 850 - 1275cc MG Spec engine - Turbo build soon....

The other problem is that boost is addictive and once you start dring the car you want more power. Then you question if you have done the right thing.

I built my 998 Turbo as an mpg project. But I just cannot keep it off boost because it brings a smile to my face. Mpg just goes out the window.

I'm building a 1293 Turbo for another car to feed my addiction

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."

Lol Paul, I hear you. Boost is addictive. I'm shooting for around 65-85 bhp to start with, as I'm not doing a full up rebuild, just a freshen, with more chamber capacity. Once I have the money together I'm going to pull the motor apart and give a full crower treatment for turbo use, and I'm hoping for 150 bananas, but anytHing over a hundred I'll take. I also want to work on siamesed injection at the same time, after I get the turbo running on it. I'll keep you posted.

oh, and beautiful crank by the way.

Reading out this site and thinking for myself, I ended to the following conclusion :

998 are easier to turbo than 1275.

You just drop a 12G295 on them and anything head related is done.

998 engines are cheaper to buy.

Also, being a smaller engine they are easier on the drivetrain

So in the end they work out cheaper and not that much slower.
I don't know what a 1275 - 10 psi just machinde for lower CR (not the holly molly Benross therapy) is putting out but I guess 120 to 130 ish
when a 998 does 100 without the head work and possibly without gearbox evolution.

Going this way, a 850 with a 12G295 head can use a skimmed one, would be even easier on drivetrain so maybe more cheap ?

Edited by Advantage on 20th Jan, 2010.

Rusty by nature

I wouldn't even bother skimming the 12G295 head, would give really low compression, but would make it so you can run higher boost without messing with the block, if you're going for just a quick turbo jobbie. I think it would be safe to run 10 psi with a freshened motor if you had a 12G295 head on it, or a similar combustion chamber at any rate, without worrying too much. As far as cheaper, I would say probably not, as you would need to get the cam machined to take bearings, and I would recommend getting new pistons, crank and rods built for turbo use, if you plan on turning up the boost at all. And that can get spendy.... When I get mine done, I'll post total cost so people have some idea what an 850 costs, compared to the others.

-James

ok, say for instance i didnt skim the head and it gave me a low C/R, but i would have to run realy high boost in order not too loose power? is that correct?

p.s what cam are you going for? sorry forall the questions.

Edited by richardsoniscool on 20th Jan, 2010.

1978 - 850 - 1275cc MG Spec engine - Turbo build soon....

Edited by robert on 20th Jan, 2010.

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

The biggest problem on an 850 are the crank thrusts with the size of a peanut. Might be a problem with an orange or grey clutch.

RTS clutch?

If something is worth doing, it's worth doing half of.

A standard clutch of my 998 was fine at 9psi (I guess between 80 and 90 bhp), so will be fine for this build I guess.

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

www.twin-turbo.co.uk

You should also use some 998 conrods.

The 850 conrods have pinch bolt on the little end and are no good for high performance.

If you use skirted 998 pistons with fully floating gudgeon pins, then you will need the early A+ 998 conrods with a bushed little end.

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."

How about throwing the 850 crank in a 998 block and anciliaries ?

Saves some machining (appart from deck height)

Robert, the 1275 power I guessed was on an otherwise standart 1275 without machining at all as a 998 + 12G295 head would be.

What about gearbox strenght up to 100 bananas, is it true or just my imagination ?


What I said about the skimmed 12G295 was to conclude that there are more skimmed 12G295 heads on the market than untouched ones. You just have to see how members on here are pulling out guns when you just mention skimming one

Rusty by nature

Putting the 850 crank in the 998 block is far from straightforward.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=255672

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."

Apparently it is not, yes.

And appart from the side thrust washers, anything else ?

I mean, you already did half the job for anybody after you, didn' you ?

Rusty by nature

Sorry for the thread hijack but.

Paul, is that crank really as black as it looks in the photos in real life, from the heat treatment process?

James

Yup, its pretty black

Yeah, lower compression is going to mean higher boost to keep the power, generally, somebody will be beating down my door here soon to correct me I'm sure. As for cam, I'm thinking about going SW-5 or maybe a phase cam. Since I think I'm one of the first to do this on this forum, I'll definitely be doing up a build thread once I get started in earnest, right now I'm sorting the shell. As for clutch, I think wil-h will be right, a standard clutch to start with, but I doubt I'll ever need more than an orange. I'll start the build thread this weekend, with pics, so people can see where I'm at.

-James

Cheers james, im sure i will learn alot from you over the next 6months /year. Will be fun when we are done though

On the CR front my point was that i would need to run high boost and as this is gonna be my daily - can i afford to run too high boost? It might just drink fuel.

Would i lose alot of power by running a lower CR and lower boost, then having the option to up the boost when i need it, i.e to smoke some chav or at the strip?

Edited by richardsoniscool on 20th Jan, 2010.

1978 - 850 - 1275cc MG Spec engine - Turbo build soon....

Edited by Paul S on 21st Jan, 2010.

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."

Told you someone would step in. Lol. Thank for the clear up Paul, I couldn't figure out how to word it. Been working my arse off lately and words seem to escape me to figure out how to word things like that.