10-12 PSI on a stock block 302?

89LX-XB1A · 02-17-2009, 09:40 PM

Does anyone know if a stock block 302 can handle 10-12 psi from a supercharger, with a good tune. I keep hearing about the blocks cracking. The car is a 89 with 115,000 miles on it. I'm going to get a 306 built, but its going to take me a few months to save up the money to get it. Meanwhile i kind of wanted to go ahead and put the supercharger on the car with the fuel system,exhaust, etc....

94CobraPace · 02-17-2009, 09:44 PM

Stock block will handle 10-12 psi with a good safe tune, most of the time. There are always going to be a case where the stock block split. Stock blocks are good to 450 -500 rwhp if the RPMs are kept below 6300 rpms or so.

89LX-XB1A · 02-17-2009, 09:46 PM

Thanks for the info

TimMcc · 02-17-2009, 09:49 PM

No problem at all.

I went over 20,000 miles on a 100k shortblock with afr 185, edelbrock intake and a tweecer with 14psi from an S trim.

Got rid of it to upgrade to a stroker.

blueline · 02-17-2009, 09:55 PM

im running 10-16lbs on my 107k stock motor. no issues at all

keesor · 02-18-2009, 10:34 AM

Nobody can say yes or no. It seems to be a crap shoot, some run well over 500rwhp for years with no problems, but others split the block at far less horsepower. Personally I've been running over 500rwhp for a couple years now with no problems. But there are no guarantees, just be prepared that if you do it, you could do some serious damage to all of the parts on your motor, including heads.

Good luck!

heedz up · 02-18-2009, 05:42 PM

I would stay with the stock 302. Don't go 306 you are just making the walls weaker.

Rich Gill · 02-19-2009, 07:34 AM

Quote:

Originally Posted by heedz up

I would stay with the stock 302. Don't go 306 you are just making the walls weaker.

+50.. its silly to build any kind of bottom end in these cars using the stock block... You can EASILY make over 500rwhp w/ a stock short block and a "built" bottom end will split the same way. The rotating assembly isnt the weak link, the block is.

99Exploder · 02-19-2009, 09:10 AM

I'm running about 12psi with my 100k+ factory shortblock with no issues. I had my car chipped on the dyno on a very conservative tune. I don't spin it over 6k. I actually shift it at just 5600. So basically if you get a tune and don't over rev the motor, it will increase your chances of not splitting your block.

Dule_Pacov · 02-19-2009, 03:12 PM

Quote:

Originally Posted by TimMcc

No problem at all.

I went over 20,000 miles on a 100k shortblock with afr 185, edelbrock intake and a tweecer with 14psi from an S trim.

Got rid of it to upgrade to a stroker.

how much power did you make with this set-up

89LX-XB1A · 02-19-2009, 04:10 PM

when i get the 306 it will be a dart block

bonzer · 02-19-2009, 04:44 PM

i ran 15+ pounds on my 306 with hyper pistons and S-trim. stay out of detonation and keep RPMs under 6000 and it "should" be okay

it's still a time bomb though.

89missle · 02-19-2009, 11:29 PM

Quote:

Originally Posted by 89LX-XB1A

when i get the 306 it will be a dart block

If your going to spend all that money on a Dart block, and the parts to go with it, why would you only go 306 inches?????
Why not go with a 347 or a 331??

smurfmobile8586 · 02-20-2009, 12:14 PM

hell 4.125 bore block would be sweet its the same cost

TimMcc · 02-20-2009, 05:07 PM

Quote:

Originally Posted by Dule_Pacov

how much power did you make with this set-up

Never dynoed it, was tuned on the street with a Tweecer rt. Wish i would have, Im sure it had to be 450 +/- rwhp.

89LX-XB1A · 02-20-2009, 10:26 PM

The reason i'm not going for a 331 or 347 is because i'm see people with 306's putting down 550 to 600 to the wheels and thats all im trying to get. The more you bore a block the weaker(the block) will be etc......... Also i've seen a few people with 302 blocks stoke them out to 347 and put a rod out the side of the block under boost. I've heard that a good set of H-beam rods,nice crank and piston in a 306 makes for a fairly tuff motor. I'm just trying to keep a driver freindly street car that's all.

89missle · 02-20-2009, 11:00 PM

Quote:

Originally Posted by 89LX-XB1A

The reason i'm not going for a 331 or 347 is because i'm see people with 306's putting down 550 to 600 to the wheels and thats all im trying to get. The more you bore a block the weaker(the block) will be etc......... Also i've seen a few people with 302 blocks stoke them out to 347 and put a rod out the side of the block under boost. I've heard that a good set of H-beam rods,nice crank and piston in a 306 makes for a fairly tuff motor. I'm just trying to keep a driver freindly street car that's all.

Quote:

Also i've seen a few people with 302 blocks stoke them out to 347 and put a rod out the side of the block under boost.

How much boost, and what were the conditions? ANY motor can be trashed for any number of reasons, (even a Dart 306).

A Dart block can easily be bored to 331 or 347 without ANY problem. If you only go 306" youll have to lean on it that much harder to make the power your looking for. A 347 or a 331 can be made to make those power numbers you want in N/A form.
Add a little boost and you EASILY make those numbers without boosting the hell out of it, or revving it to the moon.

89LX-XB1A · 02-21-2009, 09:48 AM

After doing some checking around and calling a few place this morning, I think i will go for a 331. Thanks for the info for

modo · 02-21-2009, 02:37 PM

Quote:

Originally Posted by 89LX-XB1A

The reason i'm not going for a 331 or 347 is because i'm see people with 306's putting down 550 to 600 to the wheels and thats all im trying to get. The more you bore a block the weaker(the block) will be etc......... Also i've seen a few people with 302 blocks stoke them out to 347 and put a rod out the side of the block under boost. I've heard that a good set of H-beam rods,nice crank and piston in a 306 makes for a fairly tuff motor. I'm just trying to keep a driver freindly street car that's all.

306, 331 and a 347 have the same bore diameter. the stroke is a different length

Jeff Smith · 02-21-2009, 05:50 PM

not a preblem. I have made 15psi of boost on my stock bottom end w/over 105k plus miles..

heedz up · 02-21-2009, 11:26 PM

Quote:

Originally Posted by modo

306, 331 and a 347 have the same bore diameter. the stroke is a different length

Thank you

rob10s2 · 02-22-2009, 10:24 PM

sorry for the hijack, but i have a similar question. looking to run much more boost on my 94 with an s trim. right now its got a 3.75 8 rib pulley on it from the last owner making about 6 psi. with stock heads, what pulley size/psi should i look at getting for around 400-450 rwhp? also, will i encounter massive detonation? this is obviously with a tune and btm. thanks!

96-2valve · 02-24-2009, 09:51 PM

Quote:

Originally Posted by TimMcc

No problem at all.

I went over 20,000 miles on a 100k shortblock with afr 185, edelbrock intake and a tweecer with 14psi from an S trim.

Got rid of it to upgrade to a stroker.

What kind of pulley setup did you have? inj, tuning? any times?

Speeds8erM-1 · 02-26-2009, 10:18 PM

http://videos.streetfire.net/video/P...ang_143789.htm

Friend's car, when he bought it, it had already had a turbo on it for years, at 12 psi or so, he got it and upped the boost to 17 on the 12 psi tune, just threw in a couple gallons of 118 and it made 530 rwhp and 615 rwtq. Put a 70mm tb on it, and ran it in some cold weather at 14ish psi and it went 104.93 in the 1/8 at 3650-3700 pounds, so it had to have been making some power. Had over 105k miles on it too, never broke, block was o ringed. He only shifted it at 5000 though. Another friend has the car now, without the turbo kit, took apart the shortblock and said it still looked pretty good as far as cylinder/bearing wear.

His other car at the same time was an LX hatch with 12 PSI from an S Trim, NX 100 Shot, AFR 185's, Cam Motion Cam, Victor 5.0 Intake, it made 2 passes on the bottle at the track, a couple playing on the street, and a few blower passes without the bottle and never broke, but it didnt have alot of street or track passes total. Rebuilt 302 with Probe Pistons and a girdle. It only got run on race gas too.

Another buddy of mine split his girdled stock block 347 after only a few months with his T trim setup years ago.