Hello all,

Small question, I moved overseas and pump gas here is 95 and 97. A few months ago my engine seized and on rebuild I put 10.5:1 JE and Eagle rods. With this gas, can I safely put a Hahn turbo?

Its sad seeing these turbo diesel VW golf and other euro cars with little weight taking off with less HP.

Originally posted by manolo38
Hello all, Small question, I moved overseas and pump gas here is 95 and 97. A few months ago my engine seized and on rebuild I put 10.5:1 JE and Eagle rods. With this gas, can I safely put a Hahn turbo? Its sad seeing these turbo diesel VW golf and other euro cars with little weight taking off with less HP.

There are a few board members here running turbo with 10.5:1 compression. A little searching should be able to bring you some more info on the topic. Personally I would look into using the hahn portfueler or MSnS b/c of the lower room for error when tuning a higher compression motor for boost.

Originally posted by manolo38
I moved overseas and pump gas here is 95 and 97

octane rating I assume? The higher octane fuel will help a little with the knock issues sometimes associated with higher compression, but your method of tuning will be extremely important at that compression ratio. It s definately possible by all means. Megasquirt would definately help with that set-up.

Originally posted by dsmtuner1

Originally posted by manolo38 I moved overseas and pump gas here is 95 and 97

but your method of tuning will be extremely important at that compression ratio. It s definately possible by all means. Megasquirt would definately help with that set-up.

you would have to retard timing and tune and run race gas. hor many psi do you plan on running? i can tell you what octane will be safe.

dj420a ran 20psi with his 10:5:1 comp. No timing retard was needed.
Then his headgasket blew.

He tuned with megasquirt.

I'm running 10:5:1 comp as well. I ran 8 psi on 94 or 91 octane on a sfmu with no knock or other issues.

I did however pick up and currently installing a megasquirt as I hope to surpass the 20psi mark.

Originally posted by Resol

Originally posted by dsmtuner1

Originally posted by manolo38 I moved overseas and pump gas here is 95 and 97

but your method of tuning will be extremely important at that compression ratio. It s definately possible by all means. Megasquirt would definately help with that set-up.

you would have to retard timing and tune and run race gas. hor many psi do you plan on running? i can tell you what octane will be safe.

Why would he have to do any of that except for the tuning part? I never did. I ran 97 all the time and sometimes 94 when the gas prices went up.

....and just for the record^^^^^^ I only ran 20psi for about a week and only that long cuz I was trying to tweak the fuel to make 20psi work, however it didnt, so I went back to 17-18psi.


.........goddamn NAPA headgaskets, lol.

I ran 15-16psi for awhile with a super 16G turbo and 10.5:1 compression. No timing retard and i only used the SFMU. Ran great and felt a difference when i changed to low compression. The only reason i changed was b/c i upgraded turbo and wanted more boost. But for the 10.5:1 compression, i loved it and you can do it and be fine as long as everythings done right.

Originally posted by freddy_00_69
I ran 15-16psi for awhile with a super 16G turbo and 10.5:1 compression. No timing retard and i only used the SFMU. Ran great and felt a difference when i changed to low compression. The only reason i changed was b/c i upgraded turbo and wanted more boost. But for the 10.5:1 compression, i loved it and you can do it and be fine as long as everythings done right.

I second that. I ran like 8 psi with the basic Star setup and that car was responsive and boosted quick, this was 10.5:1 pistons. Got some decent gas mileage also. I have a locomp 10psi setup now and its laggy :( It made some pretty bad smog numbers though, and I didn't install them properly so I had to get rid of them :( Running higher boost will be harder to tune but if you can get higher octane gas and don't need to do any emissions testing I'd say go for it.

okay guys there's a key word here: Overseas

domestic fuel in north america uses an average of the ROZ and RON octane testing methods. most countries outside the US only go by the ROZ number which is higher. the octane numbers of 95 and 97 ROZ are comparable to 90 and 92 octane stateside.

I learned this from my old Porsche, by the fuel filler there is a sticker that says it needs 91 octane ROZ which really works out to about 86 octane ROZ/RON

the lesson, it's all the same, don't think that they're really getting that much better fuel over there and don't do anything stupid that might blow up your engine

Originally posted by HadesOmega
I ran like 8 psi with the basic Star setup and that car was responsive and boosted quick, this was 10.5:1 pistons ... It made some pretty bad smog numbers though... if you can get higher octane gas and don't need to do any emissions testing I'd say go for it.

Really curious about this myself - what specific parameters went out of the smog limits with hi-comp pistons? Some of the local guys had trouble smogging their lo-comp setups in SoCal. I've never been able to get a definitive answer as to what is failing. Is it NOx, CO, or hydrocarbons? TIA!

well its a 420A thing but it failed HC by a little bit but could never get it to pass. Then it just started failing everything and gross polluter everything. I'm thinking that the oil burning fouled up my sensors and stuff and those total seal rings suck balls, since you have to take out your PCV. If maybe I had another car and time and money I'd see if could get a NT hicomp engine to pass smog with normal rings. I don't see why it wouldn't my car just can't pass smog, even now I haven't even tried with the locomp pistons O_o

Originally posted by HadesOmega
........get a NT hicomp engine to pass smog with normal rings. O_o

FWIW, I passed CT emish at 10.9 comp (JE pistons and rings) with AFX ECU and crower 2's. Dunno if that helps.