I was readin an issue of Hot Rod and they had their reader's write in and the one with the best engine combo (most hp per cubic inch) would win there dream engine. The guy who won for chevy motors came up with a 306, from what i grasped from the mag they took a 327 block and then dropped a 283 crank in it. from the dyno data i saw the motor was making around 400 hp @ 6800 rpm. does anyone on here have this combo? or have you seen it work? I would love to have a high rev motor thats not a 350 or a 383 and this sounds like a prime candidate.

 

A 327 (or 350) block and a 283 crank is a boring old 302.

It's a prime candidate for what? It won a pointless "horsepower per cubic inch" contest. I'd rather have more horsepower per car.

 

It would be a prime candidate 4 and engine swap. I want a combo that will rev to the high heavens. just cuz u think a chevy 302 is boring does not mean everyone else does. I am looking for a platform that's different with potential, and this motor combo sounded like just that.

 

Truly high RPM engines are different enough, you don't have to sacrifice displacement just to be different.

 

If your hellbent on destroking,go with a 400 block,drop in a 350 crank with some bearing spacers.Will rev just like a 302,or 350,or whatever,but you can sleep at night knowing that you both have a destroked engine,and still are making power.If your worried about image,just say you have a 302,I'll never tell anyone it's a 377

 

LOL that sounds like a good idea. its not like i'm hell bent on this combo i was just wondering if anyone had tried it on the boards.

 

The 283 crank in the 4" block has been around since the early-mid 60s. It's nothing new. And yes, it's been "tried", by lots of us that have been around long enough to remember the days before the 350 was widely available; I had such a motor myself. Mine was a 283 block (3-7/8") bored out .060", which took it to about 3-15/16"; a 292, instead of a 302. Same basic deal, just needed another sheet of paper's thickness shaved off the bores to be the same thing.

The factory even "tried" it. That was the original motor that was part of RPO Z28. The factory downgraded the stroke from the 327 stroke to meet class rules. They wanted to race it in SCCA's Trans Am series, and the limit then was 5 liters, so that was GM's combo to make the limit.

Note incidentally, the Trans Am did NOT race in the Trans Am series, until MUCH later. As has been typical of Pontiac, they merely licensed the name. Posers.

The 302 was not as powerful as the 327 was, let alone the 350.

The reason it has good HP per cu in, is because HP is determined ABOVE ALL by the heads, along with the rest of the induction system. In other words, if you take a given set of heads, and put it on (say) a 327, and measure the HP; and then take the same heads and cam and exhaust and all and put it on a 350, you will NOT get 350/327 times as much HP. You'll get more than you did from the 327, but not quite that much more. Then if you put it all on a 400, you'll get quite a bit less than 400/327 times as much. And so on. On the other hand, if you put that same induction on a 283, you'll get a little more than 283/327 HP.

The point being, the smaller the motor is, the "bigger" the induction system "looks" to the motor, and consequently, the higher the HP/cu in will be.

However, you'll still get less power out of the smaller motor than you will out of a larger one, no matter what. In other words, spend more, get less; do more work, lose races. {insert obnoxious buzzer sound here}

Just because it was some other numb-nuts's "dream" engine and got printed in a magazine as such, doesn't make it win races, or otherwise be a good idea.

The same principle applies to the 377. It will make more power than a 350, but less than a 400. Again, not a good idea, unless you're racing in a class that limits displacement. You spend extra money to downgrade your power from 400 output. Somehow I have trouble understanding how this is desirable.

 

Actually the "dream" engine was the prize... which kind of says it all. The winning engine couldn't be any good, or it would be the dream engine?

 

Or you could go with a 283 crank in a 400 block giving you a 348- a buddy of mine races with this combination. For the street though I would recomend shooting for high low end torque- that's what wins stop light races. I would say go 383 or if you want a higher revving engine go witha 335.

 

That's not a 348, it's more like a 321. In any case, pistons would not be cheap for something like that.

 

my mistake a 348 is a 327 crank in a 400 block.

 

Which is fine if you're running in a 350 CID limit class.

Stupid if you're not.

A 400 of otherwise identical specs (same heads, same cam, etc.) will produce at least 10% more power than that 348.

In other words, this guy spent extra money on bearing spacers and custom pistons, just to SLOW HIMSELF DOWN, if he's not required to get under a 350 limit. A stock dimension 400, built identically, would slaughter him.

That's why people stroke 350s to 383s, and why they go faster afterwards. By extension, de-stroking a 383 to a 350, would make it go slower. So if you make a 4" bore motor go slower by reducing the stroke from the stock 400 stroke to the stock 350 stroke, then what would you expect to happen if you take a 4.125" bore motor and reduce its stroke from the stock 400 stroke the stock 350 stroke, let alone TWICE as far, like to the stock 327 stroke? Why this is so tough for people to understand, just completely escapes me. I guess it's because I'm sofakingdom I just don't get it.

 

midnite, the whole "if I decrease the stroke of my motor it will rev higher" myth has been covered and debated before.

See the sticky in the engine swap forum "327 vs 350 fact from fiction". I think there's a lot of info in that.

 

how would destroking a motor make it rev faster anyway if your valve train is floating?

 

A destroked motor can wind up to higher rpms, and in certian racing classes this is very advantageous. Most of the time, and almost always for street applications the reduced displacement will provide less low end torque, but with a well matched valve train will produce the same power. The biggest factor concerning the maximum power potential is the head flow. a destroked engine can produce more hp but only if the heads are oversized to begin with.

 

You just go right on believing that, son.

I just hope next time I'm in a heads-up race, you're in the other lane.

 

so a few things here what is the extra power going to do for you? how would just horsepower make you go faster?

how is a shorter rod going to wind higher? to be honest most the time your limiting factor is going to be valve train. not the bottom end. if your valves float you aren't making power.

if a larger engine flows more air through the same heads why can't it make more power?

if a larger engine has the ability to have greater airflow regardless of heads and we all know airflow makes power why can't the larger engine make more power?

 

Not a shorter rod, a shorter stroke.

The shorter stroke means the piston/rod don't have to go as fast in order to cover the stroke distance at a given RPM. If the piston/rod linear speed is the limiting factor, then the shorter stroke engine will acheive that piston/rod speed at a higher RPM. Since inertia (1/2MV^2) is the issue when piston/rod speed is the limiting factor, you can do one of two things to increase the RPM capability - reduce the piston/rod speed, or reduce the mass of the piston/rod. Since reducing the velocity also reduces the amount of air/fuel that is gulped in with each stroke, the best way to increase power while approaching the piston/rod speed limit is to reduce the mass of the piston/rod.

NASCAR notwithstanding. . .

 

who cares about hp/litre as long as it fits under the hood

hp/lb is what matters

 

sorry you know I meant stroke.

honestly though how often would stroke be a limiting factor? even more so if you are using an aftermarket crank of any decent quality.

how much more weight are those 302-327 pistons going to be?

 

I agree on the cubic inch factor,I was only offering a combination that will make decent power at an acceptable RPM.

I will argue,however that there is a place for destroked engines on the racetrack even when cid is not the limiting factor.When we droped from a 406 to a 377 on my BIL's stockcar,we gained about.50-.65 per lap.The torque of the 406 was just too much to overcome on the short 3/8-1/2 mile dirttracks in this area.With the 377 it was a much better situation to hook and get down the short straightways of a dirttrack.That is the ONLY real benefit I've seen from destroking.It all comes down to killing torque,which is not something that 99.9 percent of us want to do.

 

If you don't believe destroked enignes can produce more hp then look at destroked 2.0L ECOTEC's and the chrysler 2.2L guys who prefer the 2.2L to the 2.5L.

More often than not a shorter stroke will not produce more hp, but in some race applications it can.

 

Riiiight. Please put that in context as the uninitiated and ignorant ones might believe you.

Hey! Don't try and pull a Lonestar on us you Wankel lover!!! I hear the 'corrective logic' excuse and I'm gonna laugh my *** off... er blow a gasket!


That was a good damn thread come to think of it. It was the origin of the McDonald's parking lot monkey-spank and 'typi' iirc.

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It generally has NOTHING to do with the motor being destroked, it has EVERYTHING to do with the rest of the combination!

 

that's where you learn how to drive if your not getting grip then ease off the throttle a little bit till you do have grip then get on it or learn how to transition the throttle better.
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there might be some other things involved then just stroke though. short stroke doesn't automaticly mean more revs. and longer stroke motors can usually rev just as easy

 

I'm so lost right now?!?!?

 

Sigh....

https://www.thirdgen.org/forums/tech...gth-5-7-a.html

It's good for some cheap entertainment and some good geek review too thanks to RB.

 

Done a lot of shorttrack racing on dirt have you?

 

holy schnike, I can't believe you guys.... You pounded that poor SOB into the ground over a typi !


ok so it was funny, but sheesh, you guys use a lot of big words...

 

GT3/4, and forza count right?

haven't done any real short track racing. have done a few back woods dirt road stints in both my honda and mazda though and even though neither car might be putting down the same amount of power (ok I know they aren't) I still had issues with grip as well though partially due to bald tires on the mazda. have done the same thing in my camaro as well. throttle controll was always something I noticed I had to do.

 

Sonix, I warned you it was worth nothing but some entertainment, and some nerdfo care of RB. But that was the origin of the McDonald's monkey-spank line that's tossed around now and again. Best line ever!

I actually used to use that as my sig, but I kept on getting hate pm's from people thinking it was part of my post.

 

I've mistaken you as one not to care.... :shrug:

 

Where do you guys get this info that shorter strokes don't rev higher? With a properly matched valve train they do, its basic physics and it seems everyone except the people on this forum know that. a shorter stroke means a lower moment of intertia and lower piston speeds which translates to better harmonics and stability at high rpms.

 

What has been said is, if the the larger engine has a "properly matched valve train" It will rev just as high.

Of course if you stick the valve train of the smaller engine is matched for that displacement, sticking that same setup on the on the larger engine wont be the most effecient.

But if you put the valve train that is most effective for each engine, the larger engine has the potential to rev just as high while making more power.

Damn, its simple.

 

Precisely.

"In theory", the shorter stroke motor will ultimately be able to survive higher revs. However, "in the Real World"® (which unfortunately, is where I am stuck living most of the time.....) the thing that has ultimately limited the USEFUL RPM capability of any engine I've ever built, is the valve train. I have NEVER YET built one with such a MAXED-OUT valve train that a 3.75" stroke was too much, or even a 4" stroke.

If the Pro Stock guys can take a 500" big block and rev it to 9000, I don't think that too many of these people here on this forum with their TBI and TPI street cars, have much to worry about in terms of reaching the limitation imposed by their stroke in some weenie little small block. But of course, those guys also run solid roller cams with seat pressures in the 300+ lb range, lifts well over .800", titanium parts and various other lightening techniques everywhere, and nearly 1000 lbs open pressure. That's a little too much for my grocery cart, thank you. But THAT'S what it takes to reach the point at which the "physics" of the longer stroke, become significant. Not.... the cheapest valve springs that will fit ("Can I get by with my 150,000 mile stock ones?"), a $50 Summit "RV" cam, stock 2-lb valves, and so on.

Now, the guy with the 348 has an interesting deal. Arguably, that combo WILL produce more power, and at a higher RPM, than a stock Chevy 350 that is otherwise identical. Its inertial and mechanical losses are lower, and since it has a larger bore, its flow capabilities are marginally better even with the same heads. However, it will produce LESS power than an otherwise identically equipped 400, at any RPM. It only makes sense therefore in an application where there are rules that dictate a 350 CID limit. Since it will get spanked by a 383 or 400 or 434, that guy has basically SPENT EXTRA MONEY to go slower. He has used his own money as the weapon with which to cut himself off at the knees.

Everybody likes to throw around NASCAR motors as their example. Well, the reason they run a 3.31" stroke, is NOT because it makes more power than a longer stroke; it's because their rules put a 5.8 liter limit on them. If that rule wasn't there, there's no telling how many inches you'd see in those motors.

RD, since when did it start bothering you that you offended people?

 

Stek, it wasn't that I really cared that I offended anyone. And Mr. Dom, it wasn't the fact that I was 'bothering' people. If their reading comprehension and common sense are malfunctioning, tis not my problem. Having to clean out my damn PMs every other day was getting a tad annoying. I can't wait till I have to do it now with the added allowance.

 

Well not just the people on this forum. Even the magazines are getting it right: