how much will a sbf take

[AMXstocker1]

anyone have an idea of how much NA horsepower you can get out of a production block cast main cap no hardblock windsor with lets say arp studs and a girdle whats the actual block limit. i'd be curious about the same thing when referring to sbm, and sbc too. i know LS and gen 3 hemis can take alot with good internals. i'm not building any of these just trying to find the competitions limit.

[user-23911]

People ask similar questions all the time.

Generic answer........if it's tuned perfectly, you'll get a lot out of it.
If it's tuned badly it'll blow up.

What sort of SBF?
My own experience with Clevelands..........it's hard to keep the heads sealed, that's the weak point. 10 bolts per bank and heads that need modifying.
But then again, it's knock that unseals them and that was with a bad tune.


Can't really give a number?
RPM limit?
Or torque limit?

[mag2555]

550 or so seams to be the beginning of the tipping point dependant on the stroke and of course rpm!

With the G force loads trying to rip the mains out of the motor at a rate of a added 150% per every added 1000 rpm its easy to see how a Turbo or blown motor making 600 hp at 5000 rpm will live a bunch longer than a NA motor at 8000 rpm!

[oldhead]

Don't forget he asked about other engines too....

[Casper393W]

I don't know about NA but I do know that I have a close friend that has a poured D4 block in a 3000lb Foxbody with N20 has ran a best of 5.15 in the 1/8th. The car has won many "stock block" races that run here in the southeast. The engine has ran in this configuration for 2 seasons.
doing the math on weight vs et. it puts this combo near 1200.

Now the question remains, How much power is he giving away by using this stock block? I have seen cases of where a person switched there combo to include a aftermarket block and change nothing else and see nearly 40hp additional on the dyno with a high hp NA build!


Engines are like houses, You cant build a house that will stand without a good foundation to build on.

Andy

[Frankshaft]

550 or so seams to be the beginning of the tipping point dependant on the stroke and of course rpm!

With the G force loads trying to rip the mains out of the motor at a rate of a added 150% per every added 1000 rpm its easy to see how a Turbo or blown motor making 600 hp at 5000 rpm will live a bunch longer than a NA motor at 8000 rpm!

Casper, your buddies block will split at some point. 1/8 mile is probably helping. I have a stock 4 bolt Cleveland block deal out there that made 710hp with Factory 4v heads, ported and stuffed. Its been 5 seasons now. Above, I suppose, all that weight winging, at 8000 is putting more stress on it, but its making WAY more cylinder pressure on it at 5000 to make 600hp, which will also put stress on it. They just don't hold up. Sooner or later, they split either way at that power level.

[Walter R. Malik]

Most older blocks before 1986 will withstand more torque than newer blocks produced after 1986. Roller cam type blocks produced after 1993 are even weaker.

[turbo2256b]

I ran a 351C aussy NASCAR block back in the early 70s a daily driver only car I owned. all internals were aftermarket. Ported intake , ported heads, circle track cam, 2.25 intake valves, 12.5 compression, other tweaks. Pulled 650 + HP on chassis dyno. I say plus as close to 8000 rpm couldnt keep the car on the rollers at that point. Shift point ended best 9000 rpm. Had it up over 10K rpm a few times. Big hold back was the exhaust. There wast any street set up but 2.5" that would fit under the car. It would blow up aftermarket mufflers in a second. Hemi mufflers would last about 3 to 4 months before ripping the seams apart. Had about 30 K miles on it before selling the car.
Only physical issue was on the first initial run keeping it under 3000 RPM broke 2 valve springs. Fix was Crane had just come out with OTEVA valve springs.

[AMXstocker1]

we run an amc and i'm asking because there is alot of 351 windsor based competition in the class we run and the class doesn't allow billet mains or hardblock so no poured blocks and its NA only and atleast a couple of these cars are capable of upper 9s in the 1/4 and 6.30s in the 1/8th at 3000-3100lbs so there already making 650ish i'd assume. i'm trying to gauge how much faster this platform can be pushed before the webbing starts going away i know there are several 408s and a 358 so that with the et i'd guess they would be spinning more that 7000 pretty easily.

[Steve.k]

Very good friend of mine runs a factory cleveland block just dynoed at 752hp NA 408 Cleveland with a3 nascar heads. So yes take a fair bit of power.My own all iron 358 non filled block with stock crank is making 585 with fairly timid flat tappet. If you want Trackboss blocks will have cast blocks that are stock class approved and offer the factory casting numbers. Those blocks will withstand over 1000hp.

[AMXstocker1]

this isn't ran by nhra and ford performance blocks and aftermarket blocks are not allowed regardless if there nhra accepted replacement or not they had to come in a passenger vehicle. and clevelands are impressive anyway, thank god no ones showed up with one of those yet.

[Casper393W]

we run an amc and i'm asking because there is alot of 351 windsor based competition in the class we run and the class doesn't allow billet mains or hardblock so no poured blocks and its NA only and atleast a couple of these cars are capable of upper 9s in the 1/4 and 6.30s in the 1/8th at 3000-3100lbs so there already making 650ish i'd assume. i'm trying to gauge how much faster this platform can be pushed before the webbing starts going away i know there are several 408s and a 358 so that with the et i'd guess they would be spinning more that 7000 pretty easily.

The early Windsor blocks have thicker main webs and higher nickel content. At the level you are at I wouldn't worry too much. Good machine work is you friend here
It's my belief that if you have a good balance job, main stud girdle, and don't forget to have the block Sonic checked out for core shift...you should be fine.

We used to run a class here in NC like what you are describing. It was called Performance Street. Rules were 3150lbs 420ci max NA we had 5 cars running Stock Windsor blocks and our ET's ended up around 5.90's

[Steve.k]

Not sure how they would ever know its not factory? There identical to factory block and have casting number. Nmca approved and nhra for all stock classes.That maybe your smallest hiccup. The Cleveland head usually carried a weight handicap in a lot of classes. I know here in dirt track basically banned.

[turbo2256b]

The new "boss" 302 block has screw in frieze plugs. Wounder is an old Boss 302 block ok but not a FMS boss block.

[pdq67]

I've asked before about buying a 400 SBC block poured out of Ductile/Nodular Iron.

I think I was told that a foundry in England cast them, I forget.

But I figure such a block cast in, "Ductile/Nodular Iron", will hold alotta hp!

I read where stock blocks generally come unglued up around 750 hp for starters! 5.0's and SBC's here... This is what make's a BBC attractive!

pdq67