4a-c Compression Ratio

[Emerson]

Is it true that the 4A-C has a compression ratio of 8.8:1 and if it is what is the easiest and cheapest way to bump up compression, without going down the forced induction route. I realise that this will be illegal on my car as I am on my P's but will the boys in blue be able to tell?

[Des]

Shave the head.

[Trev]

I have got it listed as being 9:1, I would either get a bigger duration cam or shave the head, What fuel you running.

[Emerson]

Shell V-Power

[Des]

Bump the compression upto 9.8 to be safe.

 

Its in the FAQ somewhere, 91 octane 9.1 compression aproxx, 98 octane 9.8 compression ratio.

Edited May 7, 2007 by AE70

[tas_ae71]

i thought the standard compression was 8.6:1 either way it is very low, yes shaved head and a thinner head gasket will raise compression. 4ac's are surposed to run on 97 octane fuel acording to my owners manual.

[camerondownunder88]

Do a compression test this will give you an exact figure on your motor.

 

Also shave the head easiest way abotu free to $50 if you remove the head and take it to a shop so pretty cheap.

 

BUT if thee motor is worn and the rings are well used shall we say a shaved head will kiss the motor good buy after a short time seen it happen so just play safe don't try to pass 10:1 you will only do more damage.

 

Cameron

[tas_ae71]

how much would shaving the head/thinner head gasket change compression..?

[love ke70]

as much as you want it too ;)

[tas_ae71]

i mean will 3mm raise it to around 9:1 etc?