max hp on a stock block

The rule of thumb is about 500 horsepower. Sometimes they live for years on more, sometimes less. A girdle does nothing to add to that figure. The best they'll do is hopefully hold the halves together, should it break. The problem is that the blocks aren't thick enough along the main webbing and split right up the middle because of it.

I'll tell you how much boost I make this weekend when it fires up for the first time.

For reference, I'm going to be running the 6.88" crank and 3.33" supercharger pulleys that came as a package deal, since I pieced the kit together myself. I believe the stock crank pulley is 5.75" or somewhere near that. Stock bottom end, complete with hypereutectic pistons.

Depending on how well your E7's are ported, you might be able awfully close to 500 on the stock pulleys. What type of fuel system mods do you have?

Like mentioned, the rule of thumb is ~500 - 550.

Be careful not to confuse "boost" on a gauge with actual airflow the charger is moving. Meaning if you take a charger off of a car that is producing 14 psi and move it to another set-up it may not make as much "boost" on a gauge because the air is moving through instead of sitting in the intake making pressure. The D1 Procharger on the black car in my sig was making 12-13 psi, then the heads were changed to cnc'd AFR's and a Spyder intake was added. The boost went down to 10 psi but the hp & tq went up.

There are a few good aftermarket blocks out there. Why 700 hp? A 500+ rwhp Fox is nasty.
You mentioned 30lb injectors, they won't come close to running a 347 w/ a charger.

Im a 351 fanboy....Thicker crank, thicker block, more displacement, and most 302 goodies bolt up. 351 can get you safely to the 600-700hp mark. Tons of torque as well.

Main Girdles are designed to help eliminate main cap "walk" in the bottom end by tieing all the main caps together with a steel plate (main girdle). 6-700hp will need something around a 60-75lb injector. I personally like the Man-O-War blocks because they're very very thick. I mean hell for the price of building a 700hp 302 based block with boost that prob. wont like pumped gas....you could have a 514-557 big block stroker that will make the power you want with ease. Then later you could always toss a turbo on that and make over 1000 hp easily.

Bottom line is that making 600-700 on a 302/331/347 is going to cost more to make reliable than on a bigger engine that is naturally stronger.

For instance a 302 crank will have to be stronger than a 351 crank...why??? because the 351 crank is THICKER. Same with the blocks. And when installed a 302 block looks just like a 351....just a lil wider. If you want a price??? to reliably make 700hp out of a 302 that will give you OEM reliability plan on spending $15000 and thats a modest figure. The little stuff adds up. I know you wont be using stock bolts on that 700hp motor. Or stock anything. Youll never get your stock fuel system to support 700hp either. Im on my way to 700hp world you WILL spend $2000+ on a fuel setup for efi.....less on a carb. Unless you make your own AN fittings and braided fuel lines. Machining work on my 383 came out to around $2000 You do want it balanced, blueprinted, and a torque plate used.

Remember you get what you pay for.
But if money is no object....then State that and i can tell you how to build a Reliable 700hp car for $20,000.

one other thing . . . the strain by the belt is also going to cause issues with the #1 cap.

I have seen 2 blocks break that both were stroker (331/347) and had a s-trim. Broke the #1 off and took out half the pistons/rods.

302 heads will fit....make sure if you're using heads that are at least 200cc. More power wants more air. Only difference between heads specified for 302 or 351 are the bolt hole sizes. Any machine shop can dirll out 302 holes to take the 351 sized bolts for cheap. 302 bell housing will bolt right up to a 351...if youre using the 302 fly wheel it needs to be rebalanced to 28 oz. or you need to find a 28 oz. flywheel. for the 351. Im not sure about the rpm 2, You need a intake for a 351 because the lower intake piece is wider.

Is this going to be EFI or Carb? Efi i would go with a trickflow R intake 90mm opening. Carb i would use a Victor intake. Cheaper would be a Victor with Spyder intake made to accept injectors. If you're planning 700hp dont look at standard 302 parts even if you are building a 700hp 302. That means no 75mm intake. You need a 90mm intake and a 4" pipe. Hell maybe even a 105.. TB if youre going crazy enough. Accufab makes great stuff. Gotta build it like a big block. So when you do add boost the charger or turbo wont have to work hard pushing air down tiny intake pipes.

I'm wondering the same thing..

I'm currently in the process of getting boost on top of my factory blocked stroker and was wondering what a safe boost level would be knowing my block is the weak link even though I have a main girdle. DSS swears by them, saying their girdle allows stock blocks to handle up to 650 HP reliably and that even extreme(1000HP) 4 bolt blocks will see benefit using their girdle. Knowing that steel and aluminum expand at different rates, to me, this in itself would cause main caps to become misaligned.. But that's just my opinion as I have no testing to back it up.

My previous factory block cracked down the middle, where the cam is. This was at mid range RPMs with ~15psi from a T-trim. I've seen where they now make galley girdles which are supposed to help in this area as well. I have not read anything good nor bad about them. They make sense in theory, but still wouldn't have helped my overboost at mid RPM situation as the crank does not have enough iron around the journals to prevent this..imagine a 400 lb person riding on a kiddie bike, putting all of his/her weight into the crank and the crank bearing cylinder breaking apart from the rest of the frame. You can add metal above the bearing cylinder, and you could add some below, but it still doesn't help the existing bearing cylinder(crank journal webbing) hold any more power.
On the other hand, if the high RPM, bearing cap walking is causing the failure, I would think the main journal girdle would provide some support, similar to how rocker stud girdles help the valve train.

Procharger uses 17psi as the magic number for their superchargers to double the NA power of an engine. So you have 300 HP now and put 12 psi on it you would use the formula (12/17psi)300+300= total FLYWHEEL HP which is just above 500HP. To get 600 FWHP from a 300 HP engine you would need the indicated 17psi. Again, the more you make the supercharger work, the less efficient it will be. IMO you should run a higher compression motor, 9-10:1 and run less boost.

Here is some good reading which may help guide you through your parts buying process.
MotorSports Digest

note the injector chart, your 30# injectors will suppport 450 FWHP at 40 PSI, to get your goal of 600HP your fuel system would need to support 80psi. So an injector/pump upgrade would be in order as well. A 255 with 42# would get your 600 HP, add a BAP to get your 700+.

I'm sticking with 8# or less on my stock block which will make just over 600 FWHP. I'll probably order it with the 8# pulley which would give me around 6# with my extra cubes. My 36# injectors with 255 in tank and BAP will be sufficient(close, but good enough) running around 55PSI and a 1:1 boost referenced regulator.

My personal opinion is that 600 HP is pushing it as long as you keep a SAFE tune..don't fall into the urge to run a bit more timing or a few more pounds. I agree with the posts above...500 on the street is hella fun...Ive been in 650HP vettes and it's really pushing the fun level back on the track...if even then.

-Mat

I would look in to a main griddle, for $350 they may help, I am going to pull my 331 and put on in. I have also heard of a guy running 17psi through a stock block for years and still does to this day, lucky guy in my opinion but he did it with VERY VERY safe tuning.

Anything over 450rwhp on a stock 302 and you're basically living on a prayer. Have they lasted years? Yes. Have they split on stock power? Most definitely. Revs will kill it. Keep the revs down and a safe tune and you could very well go a few years. If you're building something that will be rock solid reliable, you'll have to go aftermarket 302 or step up to a 351, but even the stock 351 will be at it's limit for the HP you're shooting for. The fuel system alone necessary to quench that beast will run you upwards of $1500 (as somebody already noted), maybe a lot more.
Also why would you want to put 302 heads on a 351? Put 302 parts and you'll get 302 perfomance. Get ready to spend some serious coin!!! Somebody mentioned $15000? I'd say that's about right.

Sorry for Reopening Thread, BUT

My personal opinion is that 600 HP is pushing it as long as you keep a SAFE tune..don't fall into the urge to run a bit more timing or a few more pounds. I agree with the posts above...500 on the street is hella fun...Ive been in 650HP vettes and it's really pushing the fun level back on the track...if even then.

-Mat[/QUOTE]
I'm brand new to this site and just want to make a comment:

I have a 93' fox body with a stock block 302 (GT-40 crate engine and bottom end) with Trick Flow Track Heat 190s, TF upper and lower, custom cam, 12psi procharged with helical gearset, 42# injectors. I just got back from dyno tune and it put down 522rwhp and 449rwtq. This equates to roughly 600fwhp, which was the highest I was willing to go.

It is quicker than my buddies dad's Z-06 and I agree with the above comments..450-500rwhp is a blast on the street. I have Nitto 555s and it hooks well, but much more than 500rwhp and I can only see full enjoyment coming from the track. I was at 449 rwhp with GT-40P heads 1.6 RR and cobra upper and lower (all mildly ported) with b-303 cam. It had much better street manners before I changed top end and cam.

I have every intention of going to a 4-bolt main 331 Dart short block later (hopefully next summer when i have time).

Would love to hear peoples thoughts.