Daily Drivers with Hi Compression

Hey John,

My car had around 12ish CR runs fine. Just get a good tuner (Y)

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Originally Posted by aaronng

Rating-wise, our 98 is the same as their 93. A large proportion of their pump fuel has at least 10% of ethanol in it. So in that respect, our 98 octane is better than theirs. Sulfur-wise, they get their fuel from the same souce as we do.

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Yeah ive actually read that somewhere.

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Originally Posted by weezer

Hey John,

My car had around 12ish CR runs fine. Just get a good tuner (Y)

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Man i loved that car. Had so much fun comming down black spur with ya that day. Yeah definitely gonna get it tuned.

if it helps you we have run 13.1 on optimax, but u need a fair bit of work done to the support systems and a full system like autronic, motec and EFitechnologies to make it happen.

My car running in the "high 12" to 1 compression. It run fine dude :). U just need a good tune :).

I recommend dynodave if u can get him to tune it. Though his a busy man these days.

Regards,
David

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Originally Posted by pornstar

if it helps you we have run 13.1 on optimax, but u need a fair bit of work done to the support systems and a full system like autronic, motec and EFitechnologies to make it happen.

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What exactly been done to run 13:1?

Bigger injectors? Fuel pump? Standalone ecu?

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Originally Posted by WhiteAP1

Just wondering how those with a compression ratio around 12.0:1 to 12.5:1 go with daily driving and more so,how you deal with our pump fuel ?

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Great thread but I want to read more from the internet tuners before I comment on this subject and I really would like EFiOZ to join in as his knowledge is worth listening to on this subject.
Regards Dyno Dave

I think my CR would be around 12:1 wouldn't it Dave?

So it seems the fuel quality itself is fine, the key elements are really engine set up and tune.

Too easy

Ok here's my turn to get flamed. (i was bored at work)

From my memory of combustion, the reason for higher octane fuel is to stop pre detonation of fuel on higher compression engines.

Thus a good tuner should be able to tune it to ensure that your timing is adjusted enough to prevent predetonation.

I know on my 20v with the head shaved it increased the compression, but i dunno how much. It was then tuned and it was fine running 98 ron. Just make sure you get the fuel from a reputable place to ensure consistent fuel. I was told that most engines are built with a tolerance and a few mm and upping the compression slightly with a good tune was fine. The engine lasted ABIT, but i wore my piston rings pretty quick, but then i was revving to 9krpm alot without upgraded internals.

Comon Dyno Dave give us the answer now.

Its not just timing that ur worried about limbo, in effect ur limited as u have mentioned by the fuel your using and the system around it in controlling predetonation. Timing is only one element u need to keep in check, predetonation isnt caused solely by timing.

For example, Pat (efiOZ)and myself have used in excess of 16:1 CRs on racing fuels, but the racing fuel alone isnt the sole reason that we can run 16:1, its the combination of the parts that we use that allow us to use 16:1. If we were to put normal street fuel into that thing, it would literally blow the thing up. If we changed another factor for example the restrictor size, but kept the 16:1 Cr and race fuel, the engine would still grenade itself.

to run a high compression what are you planning on running as in what supporting mods are you planning on doing like sleeved block, ur bore size, rod lengths, head work etc....