K11 CG13DE raising compression

[Jeroen330]

Hello Guys,

I've god new CAT Cams Camshafts. Those have a duration from 270 degrees and al valvelift of 7,98mm.
Now i want to raise my compression for a better powerband. What seems to be the best compression?

The stock compression from a CG13DE here is 9,5:1

What is the best way to raise that?

I've sorted out that my stock head gasket is 1,20mm thick. With this thickness i've got a compression from 9,5:1. If i place a steal head gasket from 0,5mm, what will that do to my original compression? how much wil it raise?

 

[frank]

you wont gain much compression with a thinner gasket jeroen, mine,s had a 2mm headskim and it still needs more (260deg cams)
1.0 pistons are the best way to raise it really (and a headskim preferably)

 

[Jeroen330]

Thanks for the reaction..

1.0 pistons will raise.. okay...
How much does the compression raise with only 1.0 pistons?

And what compression is ideale with 270 cams?
I want to use euro 95 petrol (octane 95 and no 98)


I'm very curious about how much horsepower it wil get...:laugh:

 

[frank]

np jeroen :grinning:
it should be covered in my blog http://www.micra.org.uk/threads/22225-frank-s-k11/page13 and 11.5 : 1 C/R would be nice eh (CG,s are very det resistant so i dont think you need to worry, mine runs on gas but i had no pinking problems even on petrol )
edit, sorry previous page (12) :wasntme:

 

[Jeroen330]

Thanks Frank..

Can you tell me what only 1.0 pistons and a 0,5mm head gasket will do with my compression?

 

[frank]

Thanks Frank..

Can you tell me what only 1.0 pistons and a 0,5mm head gasket will do with my compression?

with this calculator http://www.csgnetwork.com/compcalc.html i got the cc of the chamber to 33,42 on a 1.3, and 25.27 on a 1.0 (so the dish must be 8.15cc ? ) see what you get jeroen

 

[Jeroen330]

with this calculator http://www.csgnetwork.com/compcalc.html i got the cc of the chamber to 33,42 on a 1.3, and 25.27 on a 1.0 (so the dish must be 8.15cc ? ) see what you get jeroen

dude.. i don't know all the dimensions..
help me out please

 

[frank]

actually i got on better with this one jeroen
http://www.johnmaherracing.co.uk/enginecalc.htm
bore 71
stroke 80.5
deck height 0 (flush)
chamber + dish + gasket 37cc
C/R 9.6

and 1.0
bore 71
stroke 63
deck height 0
chamber + gasket 29cc
C/R 9.6

so the dish is 8cc
and if you enter the 0 dish (flat-top piston) to the 1.3 figures you get
bore 71
stroke 80.5
deck height 0
chamber + gasket 29cc
C/R 12:1 !!

 

[Jeroen330]

Thanks a lot!

But don't you forget something?
the 1.0 AND the 1.3 have both a bore of 71..

If you place 1.0 pistons in a 1.3 engine, the stroke wil be the same.
Doesn't the 1.0 have a smaller chamber because his piston rods are longer?
I know that there is a difference between the piston rods from a 1.0 with a 1.3..

So maybe the dish isnt 8cc, but less because of the 1.3 piston rods..

 

[frank]

the measurement from the pin to the crown is the same jeroen, so a 1.3 crank and rod with a 1.0 piston comes flush/level with the top of the block also (my 2 spare engines are 1.3,s with 1.0 pistons, pics in my blog)

 

[Jeroen330]

so conclusion? it won't raise the compression?
I don't get your point.. Sorry for my misunderstanding

You say that the distance from pin to crown the same is..
So the difference is in rod that makes a different stroke.. what is the difference between the pistons that will raise comperssion/8cc?

 

[frank]

no jeroen, the heights are the same (1.0 1.3) but the 1.0 (on the left) is flat-top and the others have a dish

 

[Jeroen330]

Tnanks a lot Frank!
Now i know exactly what i'm going to do!

other pistons and 0,5mm gasket

 

[superls]

ideally you would want 1 litre pistons, a 1mm headskim (or 39 thou depending on how 'good' your engineer is) and your thin gasket, that should give you a healthy cr.

 

[frank]

Tnanks a lot Frank!
Now i know exactly what i'm going to do!

other pistons and 0,5mm gasket

bear in mind that the pins are an interferance fit in the rods tho jeroen (very very tight )
and where are you based ? and tell us more about your cams (pics ect)

 

[Jeroen330]

Thanks Frank,

I am based in Holland. State: Overijssel, City: Zwolle..
My cams are made in Belgium of England, by CAT cams.

(Type 1601204)
Duration is 270 degrees, valve lift 7,98mm like i said.
overall, there is nothing more to say..

I only need to build my 2" (52mm) exhaust system, fitting a Janspeed manifold and a cold air intake..
Other tings i am working at are brake discs at the back by fitting a rear axle from a german K11 with ABS, 100nx performance brakediscs at the front on rebuild brakes and a rollcage...

Just being busy
Waiting for a GA16 to change everything