I just saw the post by mullenh. I have heard about the 396 test. In the quarter, the short won but the long had more "staying power" and was pulling hard. It's almost like comparing a suped up rice rocket to a stock ls1. The rice might get out there first, but the ls1 will beat it in the end.

 

So I suppose that 383's make LESS horsepower than 346's? And 402's make LESS horsepower than 364's?

I can't believe the things people say here sometimes...

 

No. Now your talking about DISPLACEMENT. My recent posts were about the same ci, but a different stroke. I was never talking about displacement.

 

It's important to be clear, you know.

...and you also failed to specify why. There are legit reasons why that would be... and there are myths...

 

Hey Blk Knight,

I think after he checks out the data in post 62 he might eat his entire post on
the tail end of page 4?

 

Listen to this man, if you guys are talking about same ci just different bore/stroke combos it depends on piston speed that determins the torque. correct me if im wrong.

 

That post makes no sense in any way that I can tell. Something about heavy parts and inertia causing torque??? You may as well add in the magic hamster at that point.

It's fuel and air, people.

 

Well, according to post #82, I'm not up to speed with the common knowledge.

I guess I'll just lighten up my rotating assembly and dramatically increase my torque output.
All this time, I've been doing it wrong. Shame on me!

 

No, no! You want to increase the weight. Then, it'll have more inertia or something.

You can't make this stuff up.

 

Believe it or not people do install heavier flywheels for more inertia. That way when they dump the clutch the rpms of the motor dont drop as bad for better 60fts. I dont think it is very popular anymore though.

 

You are right this does not tell us anything you might as well have thrown in a ford 351 a dodge 360 and a volkswagen because none of these engine are the same motor, intake and cam. So it told us absolutely nothing. Thats why GM used two motors that were the same bored one asnd stroked the other in the late 60s. That is how the determined it.

 

The reason I ask is this:

Take a turbo Honda motor. Makes 600 hp and about 200-300 lb-ft. of torque. Why is the torque always so much lower in comparison to HP? If you were to boost a car with higher displacement or more cylinders (not too sure if cylinders even matter) the torque would stay about the same number as the horsepower. This is at least from what I have seen.

So is it displacement that makes the torque?

 

Oh, yes, I know and that is a legitimate thing. But to think that inertia somehow causes torque and horsepower curves?

 

Yes and no. HP > TQ is caused by the fact that HP is derived from a mathematical equation dependent on RPMs. The higher the revs go over 5252 RPM, the more you will see a larger HP than torque number.

But yes in the sense that more displacement will generally make more torque and long strokes don't lend as well to revving well over 5252 RPM.

 

displacemant makes everything

 

you are not wrong but there is more involved, crank weight, rotating mass, cam intake, head effieciency, valve size,and more. you CAN NOT COMPARE TWO DIFFERENT MOTORS PERIOD. Anyone who thought about it would know that the engineereing is completely different. People smarter than anyone who has made a post here have already answered this 40 year old question. If you stroke a motor it will favor torque. If you bore it it will favor HP.

 

We do that in trucks and 4 wheel drive vehicles particularly for off road. We actually install lighter flywheels in race cars depending on application.

 

Not quite. Boosting these small motors is a big plus because they need torque and boost by tubo favor torque.

There is no substitution for displacement. It make everything.

 

The amount of air molecules processed makes the torque. Blowers, turbos, etc. increase the air density, or pack more air molecules into the cylinder, which makes the boosted engine act like a larger NA engine.

In order to make 600 hp with only 300 lb-ft of torque, the engine needs to make that 300 lb-ft at 10504 rpm. The turbo Hondas I've seen on the dyno made power in the mid 8000 range. 600 hp @ 8500 is (600 x 5252 / 8500) or about 370 lb-ft at power peak rpm. More than likely the peak torque is even higher. A 600 hp @ 6500 rpm SBC makes about 485 lb-ft @ 6500, but probably 525-550 around a 5000 rpm torque peak.

FWIW, any 600 hp engine puts the same torque to the drive wheels at a given vehicle speed (assuming same tire diameter). The high winding engine just has more overall gear reduction to multiply the lower engne torque.

FWIW-2, a 2.4L NA Formula 1 V8 makes about 740 hp @ 18,500 rpm. That's about 210 lb-ft @ 18,500. Lotsa gear ratio!

 

Wow, a lot of people making things harder than they need to be.

Let's take a 346 and stroke it to a 383.

HP = TQ x RPM / 5252

So keeping all other things equal, what we did was increase the stroke of the engine which will yield more TQ per stroke. Since other things were kept equal, the piston speed has not changed. It will now take that piston a little longer to move up and down the cylinder since the stroke is longer. Therefore, obviously you won't be able to achieve quite as high RPM's as before.

So we are gaining torque and losing a little bit of RPM's. Since everything else was kept the same, you are going to gain enough TQ that it will be worth losing the little bit of RPM's and overall you will gain some HP (which is what matters).