Budget 998 Turbo Build
Turbo Mini Forums

We have just started putting our latest 998 turbo engine together. This is a low cost build for Axel's Mini 30 undergoing restoration.

This will have the T2, manifolds and injection from my current 998 Turbo. Target hp is 100.

A lot of parts are from other projects or out of the bin of parts, bought because they may be useful oneday.

Anyway, a set of 20773 +0.020" pistons bought of eBay for peanuts and a set of fully floating rods from Sprox:


A little used 1275 steel backed oil pump modified for use on a 998:


Homemade CMS and the proper bolts from Minispares:


Standard crank, reground and balanced by MED:


Standard block, bored and honed +0.020", decked, new cam bearings and tanked by MED:


Axels heavily skimmed 12G295 with 33/26.5mm valves, ported etc. This will give around 9:1 compression with the dished pistons:


Top secret cam :) :


MED lghtweight verto and heavy duty cover from MED:


Next job is to modify the caps to accept non-turbo bearings, drill the block for the revised oil pump mounting, make the piston buttons, clean and paint and then we can start the build.

Edited by Paul S on 5th Nov, 2011.

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."

Looking good I'll be following this for some ideas for mine!
Do the pistons have slotted skirts - if so how do you think these will perform?
Will you be taking orders for the secret cam

The 20773s would not be my first choice as they do have oil drain slots. However, the twins TT2 ran these on quite high boost without a major problem. This is going to be lowish boost - 10psi.

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 recon the cam is a 270+ reasonable cr its going for 100hp lowish boost with fi why not? Jap boys and r5 boys seem to do it but we dont

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

It is 270+, at least on the exhaust :)

You can see an improvement from higher duration and overlap if you run a high turbine A/R. The standard T2 has a largish A/R for a 998.

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."

Seeing as it is very difficult, if not impossible, to get 998 centre tang main bearings in lead-indium VP2 material, I've modified the caps to take the earlier A Series offset tang bearings:

I used a Woodruf key cutter no. 610 in the mill:



All done:



Thanks to Steve at MED for the tips.

Edited by Paul S on 9th Nov, 2011.

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."

For some reason I would really like to build a small bore turbo. 1098 pref though.

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

It a good cheap turbo engine. All the fun but without the cost of straight cuts.

Although we are targetting 100hp, this engine will probably make around 130-140hp with a bit more boost. The limit is the verto at possibly 110-120 lbft.

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."

Yep the budget side is what appeals to me.

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

oil squirters ?

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."

Do you think it is better to run the VP2 grooved bearings rather than the non VP2 solid lower type then? I have the early type main bearing caps and was originally going to modify them for centre tang bearings, but seeing what you have done maybe better to just go for the VP2's.

Just wondering where you got the rod bolts from as well, are they arp?

I would use the centre tang solid lower bearings if I could get them in VP2. All I can find are the Glacier AEM3427 in the standard material. I would choose VP2 in preference to solid.

The rod bolts on this build are standard A+. However, I do have a set of ARPs for the next build, part no. 200-6207.

If you google the part number, a few places in the UK stock them. I got mine from the US.

Edited by Paul S on 10th Nov, 2011.

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 tend to put both sets of grooves in the caps in case I cant get the bearings I want at rebuild time.

an hour or so with a file well spent IMO.

As it goes I've not had any problems using the Glacier mains, BUT I do currently have an issue with big end bearings. They needed replacing in the sprint after 10k, the old TT2 engine (that I'm checking and re-building for Ben) has a spun bigend and one with lots of wear. And the TT2-7P went through a set quite quickly (though I think there were other reasons for that.

Great idea though Paul.

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

www.twin-turbo.co.uk

Well, there has always been the arguement that the solid bottom half bearings starve the big ends of oil at high revs.

Out of interest, here is a selection of 998 bearings:



From left to right:
1. Glacier mains in standard material, solid half
2. VP2 mains, grooved
3. VP2 big end
4. Mahle VP2 equivalent big end.

You can definately tell the material differences.

Edited by Paul S on 10th Nov, 2011.

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."

Mmmm Buttons:



Soon start the final clean up and assembly.

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."

they ain't cadburys!

Still got to hide them from the kids, they eat anything :)

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."

After reading up on the subject, I would be inclind to say that the plain main bottom bearing does not reduce the lubrication significantly enough in the big ends, to ever justify considering using the grooved bottom main bearing, which will only reduce the main bearing load carrying capacity.

I say this, as I built my 16 valver with groove groove bearings (still sat on the garage floor) on word from my machinist, then read the attached document by Mahle. I think that, while not the same configuration crankshaft, the similarities are such, you could make a good assumption based on the information presented.

I read alot in the last couple of years after my center main failure, trying to understand the mechanics of dynamic plain bearings.

The point at which oil is introduced into the bearing is also critical, as if it is at the same point where the highest bearing load takes place, the load capacity of the bearing can be reduced. Cross drilling if carried out without this consideration could actually be worse than a standard drilled crank.

Attachments:

789.9kb

Checked the clearance between the exhaust valve and the block. Although the valve will only go 0.6mm down the bore and should just clear the bore by a tenth of a nats cock, I decided better make a bit of a chamfer on the top of the bore instead of a full pocket:



Painted the block matt black for better heat transfer :)

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."

that'll never get up to temerature painted black.... as its heat tranfer is 30000000000% more,

plus you want th paint the back siver so the bloch dosent absorb heat from the turbo....

Lol

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

The back of the block is going to be chromed

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 wonder how much lighter a block can be made ...

After all there are some pillars that are involved in block strenght but surely a golf ball treatement in the flat places can not really do harm (as long as it stays wather tight that is ...)
Oups, found one more occupation to add to the queue, 556th OTD idea ...

Rusty by nature