Thread: 6-71 supercharged 302 help needed

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Originally Posted by V8juggernaut

I wasn't planning on running any more than 8-10 lbs of boost. More than that would be dangerous. I like the Roots blowers better than the whipple or screw types. I'm sorta old school in regards to the way I want it to look. I already have a cruiser with my big block T-bird, I just want a hot rod that will boil the hides when I get the urge. It won't be a drag race car, although I might take it to the track just to see what it does. I appreciate all of your advice. Keep it coming, guys.

8-10 lbs. of boost I.M.O. would be to much for a stock 302 block plus I don't think at 10 psi. it will run on pump gas.

Originally Posted by erik erikson

8-10 lbs. of boost I.M.O. would be to much for a stock 302 block plus I don't think at 10 psi. it will run on pump gas.

7.5:1 compression max 12psi and run 91 octane. it will run fine. if you run 87 octane it'll ping at higher rpms do to the boost pressure. its alot of work tuning it in to the way you want it with adjusting carbs and timing and your boost but can it be done.

Originally Posted by speedy55779

7.5:1 compression max 12psi and run 91 octane. it will run fine. if you run 87 octane it'll ping at higher rpms do to the boost pressure. its alot of work tuning it in to the way you want it with adjusting carbs and timing and your boost but can it be done.

12 psi on a stock 302/5.0 block???
Your kidding right??
I have built many a 5.0/302 block and we where breaking them at the 475 to 500 hp level.

Originally Posted by erik erikson

12 psi on a stock 302/5.0 block???
Your kidding right??
I have built many a 5.0/302 block and we where breaking them at the 475 to 500 hp level.

he'll be lucky if he even see's 400hp out of it if its a stock motor plus lowering the compression to 7.5:1, but i can see where your coming from if he builds it up for the strip she'll pop. plus i said a max of 12 psi.

Originally Posted by speedy55779

he'll be lucky if he even see's 400hp out of it if its a stock motor plus lowering the compression to 7.5:1, but i can see where your coming from if he builds it up for the strip she'll pop. plus i said a max of 12 psi.

Friend of mine split two 302 blocks right down the middle of the lifter valley running a 471 blower @ 9 psi..... After that debacle, he bought one of the SVT blocks, used the same internals and no more problems. Some say the Mexican built blocks are a bit stronger, don't know, never have tried one of them....

You "might " get away with 500 hp in a 351 block .....for awhile......maybe........
The 302 block will split ,there is no might to it.......
It is when you apply that power to the ground or hook up that its too much for the block to handle,a track run is extremely hard on them ,especially on the street where it may hook unhook very hard and irregularly.

Unfortunatly its a proven fact the 302 block will split at that power level.

They make a vally girdle and a main girdle to try and help the block along ,but by the time you purchase those parts ,machine the block,usually requires a line bore due to studs for the main girdle,you are getting real close to the price of a good block,but at the end of the day you only have a girdled up stock block for almost the same price as a good block.........
Plus its only a matter of time ,before you get tired of only 50 percent power from the blower ,knowing you have alot more under there ,but cant crank the boost up is frustrating and usually leads to another engine build or you blow it up ,leading to another engine build ,either way its cheaper to get the good block first ,it will hold its value for along time.

Originally Posted by shawnlee28

You "might " get away with 500 hp in a 351 block .....for awhile......maybe........
The 302 block will split ,there is no might to it.......
It is when you apply that power to the ground or hook up that its too much for the block to handle,a track run is extremely hard on them ,especially on the street where it may hook unhook very hard and irregularly.

Unfortunatly its a proven fact the 302 block will split at that power level.

They make a vally girdle and a main girdle to try and help the block along ,but by the time you purchase those parts ,machine the block,usually requires a line bore due to studs for the main girdle,you are getting real close to the price of a good block,but at the end of the day you only have a girdled up stock block for almost the same price as a good block.........
Plus its only a matter of time ,before you get tired of only 50 percent power from the blower ,knowing you have alot more under there ,but cant crank the boost up is frustrating and usually leads to another engine build or you blow it up ,leading to another engine build ,either way its cheaper to get the good block first ,it will hold its value for along time.

Read what Shawnlee say's here.
He is 100% right.
We have done 575+ hp out of a 420 Windsor in a 1/8 mile bracket car but after about 60 pass's the car slowed way done and we had anti-freeze in the oil.
This block was prepped just like Shawn talks about above.
It put a crack about 3 inches long right down the drivers side of the lifter valley.