Had a fairly interesting conversation with a gentlemen today about putting my car on the rolling road. It turns out he won't go near anything with a compression ratio higher than 10:1 on the grounds that any engine [Datsun A-Series in this context] running above that is excessive and certain to fail.

My motor is pressing a 12.5:1 ratio and going by this blokes commentary earlier on today, I won't be able to find a tuner......

Can anyone shed any light on this? Particularly someone who actually runs a high comp ratio successfully on HO Pump Fuel.

Hi Chris, nice to see you back, :)

12.5 is pretty hight for pump fuel..

I would have thought 10.5 would be about max on Ultimate 98...

Hey Mike,

Yeah I thought I'd get away with the 12.5, as it seemed a little low for methanol.

Where are jmac's massive essay-responses when you need them - no offence John! ;)

I really don't want the inconveniences of methanol....nor do I want to double the fuel consumption.

I recon its posible maybe with a good octane booster, but ya want to be precise with the mix. I think good stuff will boost 98 to about 104

Edit: yeah Im keen for Jmac's insight

Okay, is there such a thing as good octane booster?

I'll most probably run a spacer shim/gasket to keep things fairly tame. I might as well calm the whole engine down, it's a bit too much at the moment with the cam etc.

If anyone knows of anyone running high comp ratio successfully on pump fuel [in a street application] please let me know, this'd be mighty helpful.

104 octane--- gee lpg has that lol

wat bout e85 or is that meth??
a mate was tellin me u can get 100oct from somewhere just cant remember.
in my sc setup i was runnin 98 plus a full bottle of pro strength oct booster and it was better then just 98 by it self a little less ping

Correct me if I'm wrong buy dat141 runs 12.5. On pump.

That's what I want to hear 2QK4U!

Yeah Nick, E85 sounds okay but there is some confusion [on my behalf] of the RON and AKI rating, I don't know what the RON [Research Octane Number]actually is.

Can anyone clarify on E85?

At the moment I'm basically looking for Compression Ratio VS Octane figures. However it's looking more like decreasing the comp ratio slightly and putting some decent advance[?] on the spark.

I MAY be able to get away with some timing advance and some bottled stuff but I really don't like bottled stuff.....just don't trust it.

Chris

meth inj it meth aint that much and from memmory jmac can tell u where u can get it from and the other names for it!!

ill be doing the same thing once i finish my sc motor build!!

thanks nick