I am thinking about destroking a 350 to like a 327 and running like 6500-7 with it. I am not entirely crazy and going to try this on a TPI but i do want to try it on a stealth ram. Do you thinkn the Stealth ram with good high flowing heads could accomadate 7000??? Also has anybody heard of a 320 small block. I had a guy offer to sell me one, said i could turn 8 grand with it all day, but thats a bit much for me, however i am very curious to what bore and stroke a 320 is? Also would 7000 be an accaptable range in RPM for a destroked 350 (4.000 bore x 3.250) provided componants are high quality. I was also thinking a destroked 400, but i wasn't sure just how high i could turn one without sending the piston out the side of the block.

any ideas or comments would be great.

 

I am running a small main 1967 327 with a Holley Stealth Ram. I shift at 6500. Engine easily sustains 7000. I had an Isky 280HL cam with the HSR. The isky was .485/.485 lift single pattern, 232@0.05 duration. Its rated power band was 2500-6800 with peak hp at 7000 rpms. I am running a Comp 275 that is only a tiny bit smaller than the Isky currently, still with the HSR. A 327 is a very small engine and the stealth ram easily accomodates it. This will definitely do what you want it to. A 400 cube motor with a stealth ram would still rev to 7000 with the right heads and cam.

On the "320" it must have been a "302" small block. It was even shorter stroke than the 327, same bore. Yes it will rev very high, but the displacement is tiny. RPM's aren't everything if you don't have enough displacement to back it up.

 

a destroked 400 would run 7000 without popping? Very interesting... Im thinking my 350 sitting in the garage with a 307 would be good and i would feel safe revving it 7. its good to hear that the stealth ram still makes power that high

Thanks for the info

as far as the 320 i have never heard of it, i know the 302 is a shorter stroke of 3.000 and i dont want something that small, but he def said 320.. i ask cus i have never heard of it before. He might be mistaken in what it is and it might just be a 327, who knows.

 

Why in the world do people hold to the fallacious belief that destroking a motor is performance enhancing?!? It's performance hindering!!! The parts you employ will determine what you can push the motor to and where you will shift. A 383 and 327 can be made to run at the same rpms and if the part's selection was done properly, the 383 will make more power!!!

 

Exactly. No matter what cubic inch the motor is you can rev it as high as your heads/cam/intake will feed it to. My dad's blown BBC turns around 9600 every pass. My cast-cranked 355 turns 7200 regularily, 7600 sometimes. For the bottom end, you simply have to use good enough components to with stand the added stress of the reciprocating weight. As the old saying goes, you build the bottom end to stay together, the top end makes your power.
- However, I don't agree on the de-stroking is a waste. It all depends on your combination. I've seen to many dyno numbers showing that bore and heads make hp, more stroke just makes more tq and a more broad power band. On many cars, that just puts you past the point of available traction.

 

I didn't mean that a destroked 400 would rev to 7000 rpms. A regular stroke 400 will rev to 7000 rpms if it is built properly. You seem to be under the mistaken impression that large displacement, stock length stroke engines will not rev without "popping". What you are thinking of is valve float which has everything to do with stock weak valve springs and stock cams, and nothing to do with stroke length. Like was said, any size engine can rev as high as you want if it is built with quality components. And making your engine smaller is not necessarily a good idea. I certainly would take a 350 over my 327.

 

I have a poked and stroked 400 tha sees 7800 all the time... lightened cast aftermarket crank too

 

Not pretending to be an expert ,,,,But I thought destroking lessened the angles on the rods. Thus they are less stressed at high RPM. Maybe it's not an issue with high quality big buck parts, but maybe it can be beneficial to those on a budget. I don't know You can tell me to STFU and quit polluting the thread.

 

THERES NO REPLACEMENT FOR DISPLACEMENT

 

- and "The only thing that beats cubic inches is cubic dollars"

- but it doesn't always hold true...ever tried getting 540ci KB block, Big Chief heads, 1671 Kobelco Superman, etc to hook on a 10.5 tire? Mild tune-up = 2500hp, now try to get it down the track......

 

I agree with most of the tread, but stroking a motor does place more stress on cylinder walls and i do agree that with the right componants anything can be revved out, but im thinking with a nice short stroke and high quality components i can reach the higher RPM faster and with less stress on things like cylinder walls. As far as valve float, that wasnt what i was referring to at all, more so the ability to have a daily driver that winds out the R's and will last. I think 327 CI will be just as effecient as a 350 at higher RPMS, i realize i am giving up torque for this combination, but in my third gen traction was a problem from the factory and i thought it would be cool to run a small block at 7000 everyday. (even though gas is 3.00 dollars a gallon here. )

These are all just thoughts for now, while i drive around in my average build up 350 with a cam, pistons, and heads, but im looking to do something a little more unique with the next build up.

 

My cast-cranked 355 turns 7200 regularily, 7600 sometimes.

Is this cast crank stock or aftermarket? A cast cranked 350 turning 7200 regularily is a lucky sight in my opinion. My buddy had an LT1 that he turned 7000 max with and that was pushing it. Im not saying i dont beleive it turns that much, but its a chance everytime it does. I want to build something that i can rely on at 7 grand for more then a quarter mile.

 

most of the race motors i seen like circle track cars and high horsepower twin turbo cars ment to go for top speed runs and such use destroked motors.

its something about big bore and short stroke that those guys love. from what i seen, usually the same cylinder head will flow abit more with larger bores so that usually means more power can be produced. these motors are 352's 360's, and 377's based on destroking the 400 and such. they run very high rpms and make good power.

i know any motor can be spun high if the right components are used.

i think its less stress on the motor and more efficient to have short stroke since the piston travels less distance during the compression and expansion strokes. longer stroke with longer rods makes piston travel longer and the inertia of the mass of the piston traveling that far and that fast and suddenly stopped and forced back in the other direction has to be alot less than if a shorter distance was used in the bigger bore/shorter stroke motor. it seems like the motor would have to "work harder" to move the piston in a longer stroke application. this might make it less efficient and produce abit less power. just my opinion on what i think is going on.

i would be very interested in seeing a comparsion between a destroked 400 377inch small block vs a stroked 350 small block mking 377 cubes. with same cam/heads etc.

 

The ultimate power-making capacity of an engine is determined by the bore. It is the surface area of the piston that is key. The stroke more or less determines the torque and the torque band. This is why race cars use short stroke high-revving engines. When you are limited on the displacement you may have, you want to "spend" your displacement on bore. A short-stroke, large bore 350 can make more power than a small bore long-stroke 350.

That being said, though, destroking a motor without overboring it reduces the displacement and doesn't necessarily make any more power. It certainly reduces the torque.

 

yes, its a GM cast crank. Chamffered oil holes, de-bured, and polished. - Naturally aspirated I've had no problems with a cast crank up to 8k.
- Yes, larger bore takes better advantage of better cylinder heads, therefore making more hp. You run the shorter stroke for one of(or both) of two reasons:
- cubic in limit - many classes have it
- gearing - 3 or 4 shifts equals less drop in rpm, maintaining peak powerband

Think of Pro Stock. 5" bore spacing, short stroke, high rpm. They are cubic in limited, so they run as much bore as possible(takes advantage of the heads) and stroke it to be at/under the ci limit. Then gearing + 5-speed keeps the motor in peak power.
- Lower gearing(numerically higher) in the rear with a high winding motor is easier on parts in drag racing, plus allows you to stay in your peak better.
...well, easier on everything except valve springs......

 

YES MY 383 TPI WILL HIT 7200 RIGHT FAST AND YOU CANT MAKE UP FOR CID. BUT MY 383 MAKES ITS POWER AND TORK AT 5500.

 

But how much power is it makeing there ? Mine can spin high too but it makes no sense to when my power peaks at 4900 rpm