cg10de pistons in cg13de

micra.jas

micra.jas

I used the cg13de pistons to lower my compression becuase they are dished!

so for n/a engines u want high compression to go faster...therefore wont putting cg10de pistons on the cg13de crank give u a higher compression therefore giving u more bhp/torgue????????/

anyone give me reasons why this shuldnt work?
 
probably need high octane fuel, also if it increases the compession by alot wont you need a stronger headgasket? i dont know tho.
 
its the lift of the cams that beggar it up though. you would need to make pockets in the pistons to accomodate the valves, and if your swapping pistons you would be doing cams too with even higher lift and duration. so piston smacking would be imminent..

i am right in thinking though that the mini (classic) has the same sized pistons (1275 is the same sized crank thow too) so if you speak to omega or morspeed about mini dished pistons im sure they would make you a set...
 
I am lead to believe this does work, and if I vaguely remember right there is no piston vs valve battles. Also if you were to do such a mod optimax would most likely do the job fine.
 
no i havent got another k11 as yet...but mr zoidberg is right..i will be using it as my run around so im not using the turbo all day every day.
 
Has been done before in Japan, but I did see a pic of a piston with a valve-shaped mark on it - I believe it raised the comp. ratio to roughly 10.5:1 - please try this as it has been bandied about for a good few years now.
 
yeah, and i wanna know, as if im going with gsxr throttle bodies and cams etc i wanna know if when i change piston rings i can change pistons too...
 
Just gotta do some maths really to find out id there gonna touch.....safely. As for testing you gotta either turn it over by hand then bite the bullet and hope all is ok, all get very springy springs all double springs (sorry really bad on technical terms today, grammars a lil better and sopped rambling nonsense in between brackets)
 
If you can afford another gasket, then you can put it all together with some plassticine/dye on top of the piston and then turn it over, take it apart and see what you get then cross your fingers when you take it up to the redline for the first time.

All this talk is tempting me into doing it...
 
ok 1 quickie, if the con rods are the same length wouldnt it quicker and easier to get a 1L block and swap cranks with the 1.3? that'll work great on my face lift 1L, high comp (ish) with light(er) weight fly wheel.
think ill miss jae to get it done.
 
I can't remember exactly and have just got up so a bit slow, but I hink that the 1l rods are longer as both engines have the same static compression ratio so you might not be able to do it that way safely.
 
does make some sense, although you would think there the same and the ratio in the 1.3 is lowered enough with the dish in the pistons.
ill check haynes later.
 
Possibly, yes, although I can't see that the dish could contain 70cc - I am pretty sure that they have the same number on the Nissan EPC, although so do the pistons though.
 
your probaly right, if i can get a 1.3 engine next week ill try just the crank and see. not bad idea using longer conrods if you can have grooves (wrong word i know) machined out for the valves, providing pistons dont want to go through the head. lol.

as with epc number the 1.3 pistons are the same just with the dish machined out.
 
Nah ill be coming, cant let ollie down. Also the need to get drunk and finally meet you lot is pretty much why im going. Plus with the week off before usc, changing a crankshaft and rebuilding gearbox should be more than easily possible.

Anyone got a spare 1.3 crank/engine hanging around either going up to jae or live with reasonable distance of the m25??
 
If you do take it apart, could you please measure the rod length, I will do the same with my 1l rods, would be interesting to know what type of rod length ratios we could get by playing about with the different rods+bore of the CGa.
 
You sure about that Ed, I have a feeling that someone told me that they were different and (without working anything out) surely they'd have to be different to give the same comp. ratio?
 
think we were doing the wrong calculation for compression ratio.
so its gonna be easier to fit a 1.3 crank to a 1.0. no need to remove head or hone (home?) the cylinders.
 
micra.jas said:
the conrods are diffent as we compared them when my tuner did the conversion,lol
Click to expand...
Which way, up or down?? Any measurements? Still going to just swap cranks, its worth seeing whether i get valve to piston interference.
Just have to wait till i get my 1.3, should be collecting next week!
 
the conrods will be longer on the cg10 to give a smaller CC. so if the cg13 conrods are shoter.... then the flat top pistons wont make any difference to valve clearance...
 
This thread is all messed up lol. Ignoring conrods, and looking at pistons only, the extra CC in the CG13 requies extra bowl volume on the pistons to drop the compression ratio to equal that of the 1.0.

Engine capacity is only the bore x stroke and has nothing to do with the area above the piston.

Craig you may be right as I have not got a 1.0 conrod to compare with, but I was under the impression it was the same. obviously thinking about it logically would suggest otherwise. I work out that the 1.0 conrods may be 17.5mm longer, all else being equal (which it may not be)
 
Ed, I have a CG10 rod, if you could do the same with a CG13 piston, I can take pics and get some measurements up and we can maybe finally sort this out.


Out of interest, do you know how much a new set
of shells and rings ome in at?
 
dont know about shells, ask matt, but rings are around £100/set and the bores will need glaze busting to make sure the rings set correctly.

I have all the dimentions of the rods, just let me know what yours are.

Ed
 
i turned my cg10 into a 1.3 about a year ago. it turned out to be more expensive that just getting a cg13. but i learned a great deal from doing it, so it was well worth it.
the rods are longer on the cg10. and to remover the crank, the head needs to come off anyway because of the chain cover.
here's a link to my thread.
http://www.micra.org.uk/showthread.php?t=11552&highlight=cg10

we never got round to trying the cg10 pistons in cg13 as we just stuck a cg13 into rich's car instead of converting his cg10. but they should work.
 
Yeah i remember that thread, well should be getting hold of wellys super s soon, ill have a play around with the cranks and see what will give me the highest compression without interference.
 
Now I'm even more confused...
so to up the compression, should we be changing to 1.0 pistons or conrods? :D

Ashame Australia never got 1.0 micras :(
 
In the new engine you can use the same block, head, bottom end, you'll need the 1.3 crank, 1l pistons and (I think) 1l rods for highest comp ratio, although you need (possibly) to be wary of valves hitting the piston.
 
you would have to use 1.3 crank and rods with 1.0 pistons,
if you put 1.0 rods on a 1.3 crank, valve to piston clearance wouldn't be a problem because you would posibly snap the rods or crank when the pistons come into contact with the heado_O
 
Swiper said:
you would have to use 1.3 crank and rods with 1.0 pistons,
if you put 1.0 rods on a 1.3 crank, valve to piston clearance wouldn't be a problem because you would posibly snap the rods or crank when the pistons come into contact with the heado_O
Click to expand...

Well youve blown the fun i was going have then..........thanks. So we thinks 1.0 pistons not crank to increase the compression slightly with side effects, and skim the head to increase some more. Funky monkey!!!!!
 
Wrenchable said:
Well youve blown the fun i was going have then..........thanks. So we thinks 1.0 pistons not crank to increase the compression slightly with side effects, and skim the head to increase some more. Funky monkey!!!!!
Click to expand...

wooo decking the head as well?
Would there be enough clearance left after the 1.0 pistons to deck the head more? :O
 

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