Limiting factor for RPMs?

[Ron Ward]

Someone tell me if I am way off base here, but wouldn't it be most effective to utilize a stroke length that would take the best advantage of the burn rate of the fuel being used? It seems to me, once the fuel has burned and combustion is complete, the resulting expansion of gas would have a limited time to "work" against the piston. After that, the piston is just along for the ride. I'm no expert by any means. I guess I'm just thinking out loud...


Ron

[TC]

I don't know Ron, I'm still wondering how a 12:1 302 can have less piston to valve clearance than a 377.........

[dieselgeek]

I know speedzter loves his ford Mod Motors. But those things are garbage in the "average power" dept. You have to spin the crap out of them to get any power, but on a per cube basis, they come nowhere near the LS in specific output unless you only look at peak power RPM.

[JeffMcKC]

TC how fast does the piston travel away from TDC as the stroke gets bigger?

[JeffMcKC]

Ron its always about BALANCE. I find sometimes taking things to extremes helps.

Would a engine with a 1 inch bore and a 5 inch stroke make much power? NOPE, no chamber or valve size, and as the stroke gets farther away the push effect of cumbustion becomes less, and the valve has to open to exhaust and fill the cylinder (heads and camshaft).

Would a engine with a 5 inch bore and a 1 inch Stroke make power? Nope, not time to push on the crank, can you fill the cylinder in 1 inch of travel (heads and camshaft).

There is a lot of math in it, PipeMax will help a guy understand cylinder filling, but most of the time its about heads and camshafts that will dictate the rest of the engines bore and stroke.

You dont start out thinking, This Bore X This Stroke and then the heads, unless the rules dictate it.

[JeffMcKC]

I know speedzter loves his ford Mod Motors. But those things are garbage in the "average power" dept. You have to spin the crap out of them to get any power, but on a per cube basis, they come nowhere near the LS in specific output unless you only look at peak power RPM.

The power adder is where they are making HP not on Nuts

[OldMachinist]

@Oldmachinst

Not. Taking. The. Bait.

But, Boss 302 redlines at 7,500 r.p.m. with a full warranty. Competition DOHC Fords are turning even harder.

If the Feds are mandating that OEMs develop products for which there is insufficient market demand, why shouldn't they bear some of the costs. I suppose that every Bangshifter with an FHA or VA Mortgage is living in a "government house."

The difference between "Government Motors" and Ford is that a low-interest loan isn't the same thing as: (a) taking an ownership interest and giving one to the unions; (b) trashing the bondholders and stockholders in a quickie, sham bankruptcy that disregarded the law on how such reorganizations are normally done; (c) pouring in billions of tax dollars to cover losses (not loans that must be repaid); (d) having a goverment "czar" say who's in charge.

Now we are seeing TC traits. No answer when you are called out on your perfect engine.

And I agree that GM and Chrysler should have been allowed to fail but the U.S. president had to find a way to reward his union buddies for their support.

[38P]

Everyone can make up their own mind

I know speedzter loves his ford Mod Motors. But those things are garbage in the "average power" dept. You have to spin the crap out of them to get any power, but on a per cube basis, they come nowhere near the LS in specific output unless you only look at peak power RPM.

You, of course,are entitled to your opinion. But how bad is "garbage?"

Baseline: 5.3 Vortec V8: 315 hp, 338 lb/ft

2012 5.0 Ford TiVCT torque curve (F-150 trim)

1500 rpm = 275 lbs/ft
2000 rpm = 302 lbs/ft
2500 rpm = 315 lbs/ft
3000 rpm = 327 lbs/ft
3500 rpm = 350 lbs/ft
4000 rpm = 362 lbs/ft
4500 rpm = 379 lbs/ft
5000 rpm = 356 lbs/ft
5500 rpm = 348 lbs/ft
6000 rpm = 315 lbs/ft

Here's a graph from a chassis dyno pull from an average, untuned 2012 5.0 TiVCT Mustang GT (not a Boss 302)

[38P]

What does any of your posts have to do with the OPs question ?????

With all due respect, I don't see where any of my posts said @JeffMcKC. I thought you were going to put me on "ignore." No thread that rages for 30 pages stays strictly on the "OP" question.

[38P]

Chevy was selling a 454 over the counter 40 years ago that would spin that fast. No warranty.

.

And no fuel economy, and no daily-driver manners, and no clean exhaust. . . . .

No one disputes that 2-valve pushrod engines can be built to rev. See e.g. NHRA pro stock, NASCAR etc.

The problem is that the necessary ports and cam timing necessary seldom, if ever, produce acceptable service life for an OEM installation, fuel economy, or emissions performance for our now-regulated streets. Ergo some of the attractiveness to OEM engineers of multi-valve heads and independently variable valve timing (which, of course, is possible with an OHV using a "cam-in-a-cam" (Dodge) or two separate block-mounted cams (similar to the "twin cam" Harley-Davidson)).

For a "clean sheet" unrestricted racing engine, multivalves and overhead cams provide the designer with much more potential to work with. But then somebody at GM/Ilmor may prove me wrong with a pushrod 2V Indy or Formula One engine someday . . . . .

[JeffMcKC]

With all due respect, I don't see where any of my posts said @JeffMcKC. I thought you were going to put me on "ignore." No thread that rages for 30 pages stays strictly on the "OP" question.

No I have you and TC under "Post Whore", it still shows your post, no matter how off track and Bizzar they tend to be.

[squirrel]

The problem is that the necessary ports and cam timing necessary seldom, if ever, produce acceptable service life for an OEM installation, fuel economy, or emissions performance for our now-regulated streets.

There are an awful lot of crappy GM engines which do all that without needing the extra revving ability....

Like I said, it's a matter of taste.

[dieselgeek]

5.3 LS.

Real similar to the high zoot, expensive to manufacture, doesn't fit in most engine bays Ford Mod. Why spend all that money on all that tech if it doesn't do anything for us?

Meanwhile I can pick up a base 5.3 LS engine out of the junkyard for $400. How much does the 2012 5.0 Ford TiVCT cost from a junkyard?

[TC]

DG you should check out an issue of GM High Tech Performance, the latest issue has a 440ci LS motor making over 1000hp naturally aspirated........

[dieselgeek]

DG you should check out an issue of GM High Tech Performance, the latest issue has a 440ci LS motor making over 1000hp naturally aspirated........

At what point did I start caring what you think I should check out? that's the same hp/cube as the n/a Hemi I tuned 2 years ago, N/A on C25 gas. 1107hp out of 488cid.