Modding on 98 Octane
Thread Starter
Intermediate
Joined: Aug 2011
Posts: 37
Likes: 0
From: Victoria
Modding on 98 Octane
How much more room to play with compression ratios do I have running on 98 octane fuel? I've been doing my reading, but all the info relates to US 93 pump fuel. In Australia 98 is nearly everywhere so it's what I'll be running the car on always.
I'm most likely going to be running a bolt-on blower in the future, but it'll be mainly for show - not massive boost. I'd like to preserve some of the good ol' NA compression grunt as well. I suppose 400HPish would be a nice goal, 300 at the wheels would do for awhile.
So, what kind of compression should I go for? I'll probably do new heads to get it and leave the pistons stock if I can get away with it. I'm actually not 100% sure what the motor is - it's a crate motor and was new last year, other than that, that's all I know. It's not powerful at all and appears to have the original peripherals attached, and so I don't have a clue what the compression already is. Is there any way to find the compression ratio without pulling it all apart?
I'm most likely going to be running a bolt-on blower in the future, but it'll be mainly for show - not massive boost. I'd like to preserve some of the good ol' NA compression grunt as well. I suppose 400HPish would be a nice goal, 300 at the wheels would do for awhile.
So, what kind of compression should I go for? I'll probably do new heads to get it and leave the pistons stock if I can get away with it. I'm actually not 100% sure what the motor is - it's a crate motor and was new last year, other than that, that's all I know. It's not powerful at all and appears to have the original peripherals attached, and so I don't have a clue what the compression already is. Is there any way to find the compression ratio without pulling it all apart?
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
In Australia your fuel is rated as RON (research octane). In the US our fuel is rated under AKI (Anti Knock Index) which is RON + MON (motor octane) /2. Motor octane is typically 8 to 10 points lower than Research so RON is typically 4 to 5 points higher than AKI. If your fuel was rated under the AKI rating, it would be the same 93 octane the US has.
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
In Australia your fuel is rated as RON (research octane). In the US our fuel is rated under AKI (Anti Knock Index) which is RON + MON (motor octane) /2. Motor octane is typically 8 to 10 points lower than Research so RON is typically 4 to 5 points higher than AKI. If your fuel was rated under the AKI rating, it would be the same 93 octane the US has.
Thread Starter
Intermediate
Joined: Aug 2011
Posts: 37
Likes: 0
From: Victoria
In Australia your fuel is rated as RON (research octane). In the US our fuel is rated under AKI (Anti Knock Index) which is RON + MON (motor octane) /2. Motor octane is typically 8 to 10 points lower than Research so RON is typically 4 to 5 points higher than AKI. If your fuel was rated under the AKI rating, it would be the same 93 octane the US has.
I did not know the differences between the RON and AKI fuel ratings - good that I do now!
So, from what I've read, not much more than 9:1`with a low PSI blower is advisable on pump stuff?
