970cc K-Head Turbo Racer
Turbo Mini Forums

At the rpm you plan I'd be using press fit I think

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

Beaten to it! Teflon buttons it is then!

Just need a super lightweight flywheel and it should rev like fuck!

I'll do some more digging on my bike piston... Will std ones be ok you rekon? Or should I go aftermarket forged bike?

Chris

id look to see what they use in hayabusa turbo engines..

Yes i moved to the darkside

Instagram @jdm_brett

get one of Carl's flywheels

http://www.force-racing.co.uk/engine/

There is absolutely no reason to use press fit gudgeon pins. Fit proper circlips. You'll probably need custom pistons anyway, get some good circlips.

I am not sure it is just the cir-clips at fault. I think it is a combination of piston and clip. I doubt that putting a 'better' clip in would stop the problem. However if a hyabusa piston is designed with a circlip and for high revs then I would be fine using that.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

yup , both my bikes run circlips ..one to 13 k rpm ,never lost a clip yet , oh ,both turbo .

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

I wouldnt use Teflon (although I have previously), I'd use aluminium for pin buttons :)

Something worth noting, with the circlips its piston G that maks them come loose,

On an 1275 stroke A series at full revs you can see massive G, like 3500-4000, longer rods alone will drop this, as obviously will a shorter stroke.

anyway... PTFE (teflon) buttons are the way to go in my opinion,

I need to do the sums - as Joe mentions an 81.3 stroke, stock rod length 1275 at 8800rpm gives a piston speed of 25 m/s - my safe limit and most of the rest of the worlds limit for "acceptable" piston speed for an IC engine, F1 is lower than this level even though they are pulling 18k rpm the S2000 Honda engine runs at this level. Things like Nascar are reportedly running higher but not sure how they do it for the length of race they run. A 970 stroke with over 6 inch rod length will reach the 25m/s level well north of 10k rpm., but will need a good sized turbo and cam spec to lift the torque up at the bottom end.

piston speed is one of my reasons for not advising high spec K heads on re-stroked cranks, 1430/1460etc - without putting custom pistons in with long rods in there with the pin up under the botom ring to keep everything together - most people see sense and plump for the tried and tested 81.3 stroke stock rod length with a 9k hard limit.

JK

If Carling made Mini engines
it would probably be like this one!

Ok

Ive got my 970 crank!!!!!! :)

Ive also decided on the pistons - some nice forged bike ones

Just need to sort some rods with john when pistons arrive!

Next question

What do I do to the crank?

Just wedge it? Or more?

Chris

I'm no expert on the 970 crank but I belive they are better in terms of counterbalance that the long stroke cranks,

I would think a wedge and polish the forging marks out should be plenty.

you may be in luck - I'm just about to commision some 6 inch rods (ooerrh) in S big end size - also contemplating A+ big end rods at 6" as well with pistons to match std deck height on 81.3 stroke.

JK

If Carling made Mini engines
it would probably be like this one!

for a 970 with bike pistons in a non S block your probably looking for rods around 6.5"+ unless you wan to skim a load off the block.

What sort of turbo A/R should I be looking for?

http://www.7ent.com/detail.cfm?pageid=2964

Easy!

Lots to think about here. The safe option is the GT17 as we know this works on the Clan, which is a similar spec, but you want more power.

By my calculations, for 200 bhp, you'll need 22lb/min at a pressure ratio between 2.5 to 2.8.

Stick this in to some comp maps and see what looks good.

As not all maps are in lb/min here's some conversions for 22 lbb/min - 514m^3/hour or 9m^3/min or 318 CFM

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

Not to into comp maps to be honest... pressure ratio of 2.5 seems alot? How much boost is that?

Chris

Wil... would you mind showing your calculations so I can understand a bit better :)

Chris

Read this

Garrett Turbo Tech

18 to 22 psi.

Edited by wil_h on 17th Oct, 2010.

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

i seem to be posting alot of these recently :) its ford specific but good to read to get a feel for it

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Yes i moved to the darkside

Instagram @jdm_brett

Ok, I read through the garret stuff

Sorted out a spreadsheet and messed around with numbers.

How does this graph look?

About the right turbo?

Chris

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Or does this look better?

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I think the 2056,

it leaves more scope for adding boost, and also it has a higher efficiency aboyt where you peak power is going to be