www.zxrworld.co.uk

For increased compression engines ..
I've taken the base gasket off so what do I need to prevent premature detonation?

use higher octane fuel? Or is it lower you need to use?

you want higher to stop nocking, but i dout out the pump stuff is really going to make that much diffrence

as for the advancer i havent a clue dont like playing with timing ect

rene wrote:but i dout out the pump stuff is really going to make that much diffrence

My tuners, Dynotech, said it's a must to use high octane pump fuel (to stop detonation), they recond the best was Shell Optimax, now called V power IIRC, and said it would give an extra bhp over other pump fuels

with higher compresion i can understand why you would but out the pump stuff is 2-3 extra octain. Is it going to make that much diffrence? Isnt race fuel somthing like 170 or somthing silly?

only reason that i know of (so could quite easly be other reasons) to use high octain fuel is to stop Knocking (detonation) what is caused by the fuel ignighting under compresion insted of when the spark goes off

rene wrote: Is it going to make that much diffrence?

Yes, on a tuned ZXR engine, standard fuel has been known to do enough damage in one days track time requiring new pistons etc.

rene wrote:Isnt race fuel somthing like 170 or somthing silly?

No, not that high, have a look here for all the different types of race fuel: http://www.aaoil.co.uk/

Also, don't forget some classes won't allow race fuel, must be pump fuel, so the 400s are tuned for that

Ballsout Racing wrote:

rene wrote: Is it going to make that much diffrence?

Yes, on a tuned ZXR engine, standard fuel has been known to do enough damage in one days track time requiring new pistons etc.

rene wrote:Isnt race fuel somthing like 170 or somthing silly?

No, not that high, have a look here for all the different types of race fuel: http://www.aaoil.co.uk/

Also, don't forget some classes won't allow race fuel, must be pump fuel, so the 400s are tuned for that

So you reckon, removing the base gasket and porting the head will be enough to warrant using higher ocane fuel or not?

gubbs wrote:So you reckon, removing the base gasket and porting the head will be enough to warrant using higher ocane fuel or not?

TBH, I don't tune engines and don't know what tolerances Dynotech use, but it will be as far as they can reliably go. I don't know to what extent your tuning compares to my tuners, sorry, just don't know.

However, if your local petrol station supplies higher octane, then why not use it, it's a little more money but in the end could save an expensive rebuild!

My engine has undercut barrels. It runs like a bag of shite on standard fuel, only Optimax will do.

what "are" undercut barrels ?