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How much horsepower can a stock rotating assembly handle

26K views 38 replies 15 participants last post by  mike lost in cars 
#1 ·
How much horsepower can a stock rotating assembly handle?

Thanks
 
#6 ·
Well that is a very interesting question.Tell ya what.........this is too much!!.



Ouch!!!.


But I have just one more question for you



How big a wallet ya got??. LOL

Just kidding. Same old.How much you want to spend and how fast you want to go??. That hasn't changed over the yrs.
 
#7 ·
How much HP can a stock rotating assembly handle. Chevy 350. I take it someone doesnt know what a rotating assembly consist of. Your making this question more complicated than it is. Everything on the rotating assembly is stock. crank, rods, pistons, ect.... How much power can I put on these stock parts. I know its more than 1 HP per c.i.
 
#8 ·
who would have a clue you were talking about a 350? we all have different engines.Are you asking what will break? when will it break? does your 350 have a cast crank or a forged crank. Is your engine new or was it from a 1967 car? Do you have 2 bolt mains or 4 bolt mains. Is the engine original condition? does your engine have cast pistons? Give us some clues,,,
 
#11 ·
A few years ago, a friend of mine used an autozone short block for drag racing. Lasting him about 2 years of racing every weekend and drove it to work. I would say a 600 to 650 Hp build.

200cc dart heads, compcam 292H, Victor jr, 750 DP, 300hp shot N02, 3500 stall, and 4.56 gears.

Finally developed a rod knock after eating 20lbs of n02 every week for 100 weeks.
 
#12 ·
More torque, lengthen the stroke. More power , increase the revs. So with a stock engine all you could hope for is a longer accelerator pedal to squeeze more hp out. As the piston crown reaches tdc and heads back down at 2000rpm it wants to leave the wrist pin behind. At 6000rpm the wrist pin is still trying to hang onto a cast piston, but the force has increased dramatically between going up, stopping and going back down...........the rest would be history.
It would be a good bet to see what would let go first, valve spring, valve, piston crown, rod, crank, bearing????????
 
#15 ·
I made 806 in a 454 with stock rods and stock CAST crank but with forged pistons - but good cast TRW stock replacement pistons would have held up, as well. It, also, had been turned as high as 8200 in the lights. I used the cast crank because it was 5 lbs less reciprocating weight. Of course, I did magnaflux those parts to find good stock ones.
 
#18 ·
as seen as the question is somewhat open ended.. with way to many being anal about it..
most chevy 350's don't have forged factory piston, nor do they have forged cranks..
so to answer the question in the way I take the o/p asking it..
if you go grab a 350 out of a junkyard and bolt it in, without rebuilding it.. changine the cam.. and adding headers/etc..
most will make 350hp without blinking,, cast crank and pistons,2 bolt mains.. thats going off the millions of engines out there and the most likely one you'll come across..
even if the one you find has forged everything and 4 bolt mains, it don't mean anything.. it might give up way before a cast piston/crank one will. like anything it's the luck of the draw..
I beat the living crap out of a 100k 350 with cast crank/pistons/2bolt mains.. and had no problems,,
I've had low miles truck engines(forged crank/4 bolt mains) spin a bearing..
but figure you're pretty safe with any 350 handle'n 350hp no matter whats in it.. as long as it's healthy..
cast parts don't like shocks, so if you dump a clutch at 5500rpm you might find the crank on the ground..
cast pistons and happy gas isn't a good idea either.. as you have to be dead on.. with the tune..

having said that.. I sprayed the crap out of a pontiac 326 cast crank/rods/pistons.. for a good 2 years..
but thats was more of being lucker than good.. ;)
 
#19 ·
No sure about many being anal.Guys will tell us about their adventures with cast whatever and is that the kind of advise we want to provide?? After all that is saying one guys accepted risk is his O/P's risk as well.

But getting back to too many being anal,a number of members have tried a number of times to advise this O/P the best way they could by asking for details on what he has and in that way give him well founded answers. The O/P wasn't for coming in those details. Now I have been on forums like this for many,many,yrs. It is my experience that when O/P's don't post back with more info,the main question they are asking they know what the answer would be and just don't want to hear it.Or can't be taught anything.

We constantly forget the foundation of Hot Rodding isn't a budget or the cheapest found,but building the best.15 yrs ago when imported parts invaded Hot Rodding it took out one of the cornerstones of Hot Rodding and with much of it junk.

So here here is my blind unfounded answer not knowing what exactly what he has.Yes,Chevy produced a 350 hp 350.:rolleyes:
 
#23 ·
I think building on a budget is something almost everyone has had to do at one time or another. Used, traded-for and rebuilt parts are what makes the hotrodding world turn. At our junkyard, one of the most sought after 'race' parts was my Dad's rebuilt 3-speeds, for example. 4-speeds hadn't been out that long and weren't in junkyards, or in most guy's street cars either.

Heck, even Garlits started out in dragsters w/an old pair of Chev frame rails. Rails that prolly didn't cost a nickle...
 
#24 ·
Yep, back in the late 50s I couldn't afford a Muncie 4 speed and a set of 4.56 or 4.88 gears; so I rebuilt a 3 speed with the 6 cyl gears because of a 2.94 first gear ratio instead of the close ratio 2.2. We used what we could afford and make by ourselves. That's what gave us our ingenuity that even helped us later on when we could afford better parts.
Don't know why these posts always turn into "who shot John" This will be my last or second last post before I "unsubscribe" !!!
 
#27 ·
1Gary,

Good description of the situation.

O/P, you asked a most "generic" question. Please be more specific in the future to avoid all this. As you probably have surmised, such an open question is not valid. Some of us do this stuff for a living. We give our time here to "better" the hobby. We ask nothing in return. A little help would help us help you better.

Chevy made a 370 HP 350... A stock forged bottom end can easily withstand 600-plus HP.

Jim
 
#29 ·
I have a sbc 350 I plan on building for street/strip project. I am taking it to my machine shop to get it re done. (.030) I plan on using STOCK GM PARTS for my rotating assembly. (crank, rods, bearings, pistons, ect). How much HP/TQ can these parts withstand so I know what my options are when i get my top end?? (cam, heads, intake, carb, exhaust). I will use ARP bolts.
 
#30 ·
I think this is a two part question.Playing it conservative with a cast crank 400hp no problem,500hp still limited risk,but that is going to come down to the power curve and if you start hooking the car hard,the car's wt,rpm range,etc.

The second part of the question I think comes down to the SCR/DCR and today's gas if you planning for iron heads or are going to elect for aftermarket aluminum heads and then cam selection.

Apart of the machine work aside from a over bore "could" include decking the block and if you do so that could be 0 deck or .010 down.At the very least you should have the machine shop check the deck to be sure it is flat.

These days compression dictates cam choices,head selection,even exhaust which needs to include consideration for trans gearing or trans choices, rear end gear ratios,and tire size.You want to tailor you power curve so you right at the beginning of it off idle or shortly there after for a street driven car.Those loopy idle's sound kewl,but don't do much for you when the cam starts to come in at like 3,500/4,000 rpm.

The catch 22 is the physics is relativity smaller c.i. engines do produce their power band at a higher rpm band.So that development of a power band would be higher with a 350/355 vs a 383 which would be at a lower rpm range.

So the msg here is for you to plan out your build in the big picture.Don't plan on nitrous big shots with a stock bottom end.

Hope this helps.
 
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