Madabout Kitcars Forum - 400+BHP Chevy engines that live on pump gas & why &

:biggrin: Ello mates from across the pond... Been asked over & over again "can i run 400+BHP with 10:1 & 11:1 comp on regular pump gas"
The answer to that in the quick is yes BUT! there is certian combonation that will allow you to run on pump gas.
1- There is no replacement for displacement in Chevy SBC we use 350 block with 3.750 stroke cranks = 383cid this produces very high torque & BHP @ low RPM's in the RPM range you will be using on the street ,the power band or torque curve is very wide indeed 1400 to 6000 RPM
2- Camshaft selection is critical , 1,000 of engines built & 100,000's miles driven we've learned with this combonation cams with 108 centre lines
280 duration with .480 to .505 lift work best . why? tight centre lines produce more torque @ lower RPM & bonus us with lots of valve overlap
(intake & exhaust staying open together eg: see Isky Cams the 5th cycle
articale. This extra valve overlap bleeds off cyln pressures @ idle & low RPM reducing detonation ,eg; ping.
And with the engines rod length and stroke eg rod to stroke ratio works best 1,000 of dyno hrs prove that & real world testing also.
3- Next trick we use Rhoads vari duration & lift hyd lifters , with anti pump up check valve why? Were trying have or cake & eat it too , these lifters
bleed off @ low RPM reducing duration 20 to 30 degrees & lift approx .030
ths with larger cams used we do not need long duratiion & high lift @ low RPM's taking away some duration & lift produces more low RPM & torque
when it's needed up to 25% more then stock lifters ,this bleed stops as engine reaches approx 3000 RPM ,and cam specs go back to full lift & duration were we need it in the higher RPM range ,we've created a variable duration & lift cam as we drive having a milder torquey cam @ idle t0 3000 RPM and then a race type cam RPM's above that were we need the lift & duration producing more top end power , very trick indeed
Camshaft that works best with these lifters is a fast action hyd such as Isky's Mega hyd , sorry wizz bang cams simply do not work as when ,go to Isky cam web site a wealth of cam knowlage there.
4- Heads to use are very important use alum heads , alum disapates heat much faster then iron reducing cyln temps & engine ping & run on.
We like Canfields 200cc & 220 cc full CNC machined heads , why that another day .... CHEERS! mates hope we shined some light on your next engine build or purchase . Regards Daryl / Dr,Dee / Fastco Auto USA
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