how much boost can you run on a stock markviii engine

mach1man67337 · 3 Weeks Ago

i have a 1997 cobra car that was just a shell when i got it and I found a mark 4v motor cheap, anyways i am single t-70 turboing it and my turbo has a manual boost adjustment so i was wondering if anyone knows a safe boost to start at. I also read that you need to put 30# injectors and a bigger fuel pump, is this needed under low boost? I know the mark has a cast crank so i would like to keep the horse power around 400. Thanks

mustang_mike · 3 Weeks Ago

Not certain when it comes to the turbo, but I know they say 8# is "safe" with a centrifugal supercharger on the 96-98 Cobra motors which are essentially the same in the Mark VIII. Definitely look into upgrading the fuel system and have it tuned, you don't want to lean it out and cook pistons on that "new" motor.

mell0 · 3 Weeks Ago

yes you will definitely need to up the fuel system. make sure the MAF is calibrated for the new injectors too, otherwise you'll flood your cylinders with fuel.

2oo5GT · 3 Weeks Ago

+1, fuel and a good tune is definitley needed.

bboylobo · 3 Weeks Ago

more fuel bigger injectors a good tune and you should be fine.

BTW your cast crank is good up to 700 hp. at that point you might want to have it balanced.

2Manystangs · 3 Weeks Ago

look into a kenne bell "boost a pump"...a great inexpensive way to upgrade the fuel system...

mach1man67337 · 3 Weeks Ago

thanks for all your input you helped out alot.