CHESTNUTXE 7,642 Posted June 19, 2016 The weiand website say's a safe level of boost on pumpgas is around 12.1 total,in other terms a 350 c.i engine running 8.5.1 with 4 psi,but that is with 92 octane,what about our 98 octane gas ,anyone one have a formula ? Share this post Link to post Share on other sites
Thom 6,708 Posted June 19, 2016 There's no set rules on what you can get away with on pump fuel, each engine is different, combustion chamber and piston designs vary so much from different engines ( and sometimes on variations of the same engine, clevo's nuff said ) cam sizes can effect how much boost your can run, engine materials ( eg iron vs alloy heads) running an intercooler vs not running an intercooler, how you achieve boost turbos vs supercharging, fuel and spark delivery efi vs carb coil packs vs dizzy and don't forget some engines just don't have strong enough components to handle boost so there is a lot to think about you can't just say 10psi works with pump fuel because for some engines it will and some it won't 1 XPT reacted to this Share this post Link to post Share on other sites
CHESTNUTXE 7,642 Posted June 19, 2016 ok sure ,4 psi on pumpgas doesnt sound like a lot,and i suppose its more for show than go,so with 98 octane 6-8psi shouldnt be a problem with say a 351c with open chamber heads at around 9.1 ,or slot in a set of dished pistons for 8.1 and your boost will be able to be turned up even more. Share this post Link to post Share on other sites
XPT 673 Posted June 19, 2016 US octane ratings are different because they use AKI for fuel rating and we use RON. Their 93 octane is the equivalent of our 98 2 Thom and Mixalis reacted to this Share this post Link to post Share on other sites
Thom 6,708 Posted June 19, 2016 For a cleveland a closed chamber head with a dish piston has far better control of the combustion process especially with unleaded fuel Share this post Link to post Share on other sites
CHESTNUTXE 7,642 Posted June 19, 2016 I always wonderd why they were getting such high boost and hp figures on their (93 pump gas) Share this post Link to post Share on other sites
