Need to settle this and answer for everyone...

[drifts14x]

Hey there, my friend and I have been arguing about the highest compression ratios attainable on pump gas. I have always been under the impression that a 240 can't run higher than 10.5:1 on 93 octane gas, while my friend and his integra run 11:1. I want to know what the highest possible compression is that a 240SX can run on pump gas w/ no additives. Hopefully this will answer further questions about compression ratios in the 240SX. P.S. I searched.

[nab911]

You mean like totaly safe? Because you can even knock on normal compression. Just the higher the compression, the higher the chances of it happening are. We are building a 11.7:1 ka and i wont run it on less than 100.

[TrunkMonkey]

11.1:1 has been done on 93 octane.

-demetrius

[glacier985]

11.1:1 has been done on 93 octane.

-demetrius

I did it on 87 octane, and 3 injectors, dont know how, but it ran and it still does.

[drifts14x]

so Glacier, you just swapped a DOHC Head on a 1990 SOHC motor and got 11.1:1 working with 87 Octane, amazing! I hold you in high esteem. So I guess that unless anyone else can say differently, 11.1:1 is the highest.

[TrunkMonkey]

i wouldn't try to duplicate what glacier985 did. use the highest octane pump gas you can get.

-demetrius

[glacier985]

so Glacier, you just swapped a DOHC Head on a 1990 SOHC motor and got 11.1:1 working with 87 Octane, amazing! I hold you in high esteem. So I guess that unless anyone else can say differently, 11.1:1 is the highest.

Thats exactly what I did, it doesnt idle very well, but it runs. And from now on Im going to be running 93 octane instead of 87

[JonnyB4Real]

I remember readin a article back in the day about a guy and his 12:1 compression integra (I used to have an integra) and he ran 93 octane all day everyday just fine, but on a road trip in iowa he needed gas bad and all they had was 91 octane which he ended up having to use and within a half hour it killed it iirc.

[_/_/_/M aurice]

A buddy of mine has made himself a high comp KA24DE motor. The thing is incredibly strong, my guess is probably around 170whp. He's basically made a new motor.

Compression is probably around 11:1 and he uses 94 octane.

[Checkered-Member]

A BMW M3 has a well engineered I6 engine that runs 11.5:1 and after some normal wear on the motor, when put threw a road course those engine tend to explode – food for thought

[sil8tdrifter]

From everything I've ever read 11/?/? is the highest I've seen on a daily driven app. 12/?/? I've seen on N/A Drag cars, Crx's.I think it was SCC or Superstreet that interviewed that particular class (N/A) of drivers.