Escy

I use Tesco 99ron, wondering what's generally accepted as the highest compression to safely run on an n/a engine. Thinking of upping mine.

lead_foot

iTrader: (1)

Depends on alot of things like the design of the combustion chamber, design of the tops of the pistons, ect

xr2wishy

iTrader: (2)

it does depend on alot, but 11:1 shouldn't be too bad, 12:1 would need a lot of timing taking out of the map though.

OldDan

I ran 12.5:1 on Tesco 99. The option was there to run 13.5:1 but would need to swap to carless.

Escy

Engine is a Toyota 4age 20v. It's 11:1 as standard. I've got some updated cams to go in and was thinking of raising the compression to about 11.5:1, maybe more.

Minirotty

12:1 isn't to high but as said would need mapping to suit

I have one built for 13:1 but dont think it's gona like pump fuel.

timrud

I know of XE's running 13:1

Chip

iTrader: (3)

Very dependant on the cams you are using, 13:1 or even 14:1 or more on lairy cams isnt a problem as your dynamic compression ratio will be so low anyway.

Ask your cam manufacturer what they recomend, its pointless asking anyone else!