Piston options for high compression

[Antony]

I know I know..... Cg10 on cg13......

But....


I need exacts...

Bore 71mm?
Wrist pin 18mm?

Ok, so
Cbr900rr fireblade pistons,
Zzr1100 +2mm

Any other pistons that will give very very high compression?

I'm talking motorbike high... 14:1 etc.

Also, Frank..Lol....... Valves, buckets and shims for high revs.

What options there?


And I need a cg13 engine to play with.


Love You ...

 

[Antony]

Cb1100f look good.....

 

[infinity]

Think frank used corsa pistons although not sure if was for high comp or for forged for turbo cant remember

 

[F3kka]

Corsa pistons can be used for high or low comp (depending on decking the block or not) but that's for CGA3 engines.

 

[frank]

yes corsa have the same interference fit wrist pin, but have 4mm less compression height
and unlike cg ones they are,nt made from cheese
dual springs ant ?

 

[pork]

yes corsa have the same interference fit wrist pin, but have 4mm less compression height
and unlike cg ones they are,nt made from cheese
dual springs ant ?

You've probably told me this before......

So corsa Pistons will fit, and give less compression, so ideal for a boost setup

Any work done to the block to get them to fit?


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[jamieccc]

Corsa pistons from what engine?


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[frank]

You've probably told me this before......

So corsa Pistons will fit, and give less compression, so ideal for a boost setup

Any work done to the block to get them to fit?


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.5mm overbore on a cga block neil, and they give about 8:1 c/r iirc

Corsa pistons from what engine?


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the earlier (pre twinport) 1.0/1.2 jamie

 

[jamieccc]

Are they forged like some parts off the vxrs? I think the astras have forged conrods as standard if in remember right.



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[frank]

the ringlands are far stronger jamie, here is one that suffered pockmarks from detting when i cooked the engine at mallory park, yet the ringlands were fine

 

[Antony]

Dual springs frank, wild wild cams, bike carbs/itb, stand alone, cnc cylinder head, Titanium exhaust manifold, Balanced knife edged crank,

We're talking long term, race car engine building for a track day toy. I just don't want to buy stuff that's not going to work or that won't fit or do what I want.

If I can get the rotating assembly light enough, and the oil pressure high enough (for the chain tension) and with the right cams, I don't see why 10,000 rpm is out of the question.

Hondas see 10k+ all the time with longer strokes, I mean even my 4g63 hits 8500rpm.

I would like to know what you'd recommend...

Turbo is all well and good, easy to get power, but it's just not as pure a driving experience as a wrung out n/a.

 

[frank]

aye, valvebounce is your limiting factor eh ant, the oval guys add an extra washer under the spring

 

[MaxK11C]

Some really interesting stuff in here

 

[Antony]

If you are reducing the overall size of the valve spring to increase preload, surely the total spring strength isn't changed, but compressible height is, so you could end up coil bound......

 

[frank]

there is some "discussion" on it here ant https://www.micra.org.uk/threads/head-work.54171/#post-557714

 

[h701micra]

Looks more like a lesson on preload..

 

[l_jonez]

I went down the corsa route, 3mm skim off the block to increase the cr.

 

[Antony]

Surely that will reduce the overall cc of the Engine as you're reducing the swept area.... Or are you?

The piston height has lowered but so has the block, so in actuality all you've done is effectively lowered the cylinders in the engine.
Also lowering the centre of gravity.


I need to get myself a used cg13 or cga3 block...

There are more options for pistons with the cga bore size....
Hmm....

 

[l_jonez]

Ummm no, the corsa pistons are 72.5mm bore. Which ups the cc's

 

[Antony]

Ah, Gotcha. So cga3 with a rebore....

 

[h701micra]

Shorter stroke, wider bore should make for a more torque engine I believe

 

[Antony]

More hp.... Higher rpm.

So lower torque.

Longer stroke gives more torque as the conrods pivot point on the crank is further out...... Meaning bigger leverage....

 

[h701micra]

This is why I prefer suspension

 

[Antony]

Lol..

I do suspension too.
Mostly on my bike, but that's with 15x more than the car lol....

 

[Antony]

Anyone know the deck height of a cg13 piston? From the top of the wrist pin to the top of the deck?

If so, I've found pistons!!!!!

 

[frank]

20mm ant

 

[Antony]

Is that from the top of the wrist pin?
Was looking at vfr800 pistons, 17mm pin, 72mm bore....
Available brand new for £16 each....

 

[jamieccc]

Did you find if these pistons fit in the end?


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[Antony]

I need to know if the measurement is from the wrist pin centre or the top.

And your small end will need machining out and a 17mm bronze bushing fitting...

 

[Antony]

Cbr900rr fireblade pistons look viable too.

 

[frank]

Anyone know the deck height of a cg13 piston? From the top of the wrist pin to the top of the deck?

If so, I've found pistons!!!!!

20mm ant

 

[Antony]

Balls, they're only 14mm Grr...

Would need 3mm off both the head and block..lol.