As above got a question regarding my Comp Ratio.

I built my engine to 7.5:1 comp. We then decided to use a thicker Cometic multi layer head gasket instead of a Grp A, which dropped it lower again. Car was mapped a few weeks ago by Ahmed and at my request mapped Safe as i will give the car lots of abuse.

The problem i have now is the Cometic Gasket has started to pressurise the system[like many others], now i want to just fit a Grp A instead as never had a problem with these. I know its going to raise the comp and bring it back up to 7.5:1. What i want to know is does it need to go for another session of mapping or will it be alright?

Cheers Nash.

 

You could fit two gaskets

 

Changing the c/r is going to require a remap imo

 

Just wanted to know. I did tell Ahmed it was 7.5:1 and not any lower but i will ring him and ask. My mate has a set of Det Cans and an LM1 so might get him to check it first.

 

That would save you a trip back to Ahmed.

It very well might be ok, I'm no mapper but its certainly cheaper to get looked at than replace an engine

 

Fit the gasket and have it DET checked by a proffesional.

CR changes of this magnitude will only affect spark advance requirements
and fuelling will be ok.

You can take 2 degrees out of the map by linking the ignition retard pins
on the ecu which isnt ideal but will get you back on track.

ANy loss on ignition retard will be made up with the CR increase.

I doubt it will have an effect anyway as most tuners allow a safety margin.

 

You say get it DET checked by a professional Simon but tbh you can hear DET well enough on my mates car with the cans on so I cant see why you can't check that yourself.

Obviously Nash can't personally do anything about it but he would know its not right

 

Yeah my mate knows what he si doing. I Have a way i can chage the values on the the chip, so could take sound out of the ignition if it was detting. If its needs doing i will probably just take it back to Ahmed to sort tbh as like Jonny says its cheaper.