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destroke 454?
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the13thround
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PostPosted: Thu Mar 08, 2007 4:08 pm    Post subject: Reply with quote

dont stop this thread though, if you guys have anything to say ion regards to this kind of setup or comparisions between 427 and 454 stuff im sure its good to have it down somewhere.
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af2
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1933 Willys Coupe

PostPosted: Thu Mar 08, 2007 10:01 pm    Post subject: Reply with quote

the13thround wrote:
i don't know i was just wondering if anyone had numbers or dyno graphs? i guess im just curious like a cat. my friends call me whiskers. anyways im planning on just doing a stroker 496.
it seems like a good all around engine and its been done before so i shouldn't have trouble getting info on the setup, being that this is the first big block i've ever built.


This site doesnt run Dyno runs on every engine built! I wish you the best going there! Very Happy Very Happy It would be nice!
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the13thround
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PostPosted: Fri Mar 09, 2007 12:32 am    Post subject: Reply with quote

"This site doesnt run Dyno runs on every engine built!"
if it did my question would be irrevelant.
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Harold Sutton
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PostPosted: Mon Jun 04, 2007 10:07 am    Post subject: Reply with quote

I had a '68 Camaro with 4.10 gears and a 454 in it. I once ran a guys '70 that had a 427 engine with similar compression, 5.13 gears and both had four speed transmissions and similar weights. It was pretty close until the top of first gear where my bigger motor suddenly just shot out a fender on the '70, at which point he missed the second gear shift. From his best time slips it would have been a no contest from there on as mine was five MPH faster downtrack. I didn't hear any more about "how bad" he was going to beat me.
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Big Dave
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PostPosted: Mon Jun 04, 2007 11:22 pm    Post subject: Reply with quote

Lets see big bore or long stroke Hmmmmm?

First we will look at the 427 displacement also known in racing circles (USAC, SCCA circles and turns, hair pin bends, and straight aways anyway) as the seven liter. GM used to campaign the production 427 and lost. They got tired of loosing so they built a 430 to replace it. The difference; 4.400" bore 3.470" stroke stuffed into an all aluminum block with steel cross drilled caps. That was Grifo 7 CanAm racing they were involved with affiliated with teams like McLaren, Chapparal, Donohue, and the pesky guy Penske.

Back when GM actually made motors to put in GM cars that were not all painted black small block Chevys; the Poncho engineers were eating the Chevy engineers shorts with a 421 cid long stroke motor in a heavy full size NASCAR stock car. But by the end of 1962 they were the dominate force with their production engine 409 cid with a slightly longer than stock stroke displacing 427 cid. (bore was 4.312"and the stroke was 3.650"). In 1963 they pulled the plug on factory backed racing and the Mark III BBC died a horrible death.

Final argument; I give you todayís gutless wonder the 5 liter 305. It has a 3.48" stroke thanks to the stock cast iron 350 crank in the bottom of the block. However it has a hard time breathing through some really sorry heads, that and a bore of only 3.736". Now Chevy also took some production pieces and cobbled together a 5 liter engine for TransAm rules. They chose a 327 block and a 283 crank with stock 5.7" rods we get a 302 (bore 4.000" stroke 3.000"). Now which 5 liter would you want between your frame rails? (Now think about that Z/28 motor in a Suburban towing your 6,300 boat to the lake for some skiing. The 305 can do it; slowly, ever so slowly, but it will drag it there).

Any time the RPMs are in the racing range (above 4,500 RPMs) then the big bore short stroke will win that race every time because it has a free breathing bore (no valve shrouding issues), better rod angle (even with stock length rods), and the ring pack will have a fraction of the parasitic loss due to friction that you get with a long stroke engine. In unlimited (by money anyway) classes like Pro Stock or Quick 16 the guys all run 4.700" bore blocks (5" bore spacing instead of the stock 4.80" with a 3.6" stroke in the case of Pro Stock were they are limited to 500 cid). They shift their hot rods at 10,000 RPM which is boggying for a BBC.

Now if you are going to be pulling a trailer or expect the motor to idle below 2,000 RPM then I would opt for the longer stroke. Most of the cops around my neck of the woods frown on 8,700 RPM leaves at stop lights. But for racing and only racing short stroke rules. (just ask that guy af2 who destroked his SBC 400 down to 377; he isnít towing anything with his Willys so it will probably get the job done.)

Big Dave
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journeyman
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PostPosted: Thu Jul 12, 2007 11:18 pm    Post subject: Reply with quote

496.... I assume that is the stock 454's bore with stroker (4.375) crank?
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Big Dave
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PostPosted: Fri Jul 13, 2007 4:51 am    Post subject: Reply with quote

496 is a 454 that has been 0.060" over bored, and fitted with a 1/4" longer than stock stroke of 4.250". The 496 is a street motor not a Pro Stock motor. The 502 is an 1/8" over bored 454 that retains the stock length stroke forged steel crank. The bores are so large that they are Siamesed (touching) just like in the case of a SBC 400. A 540 is a 0.030" over bored 502 block with another 1/4" added to the crank. My 582 is a 5.060" bore with a 3/8" stroker crank (the longest that will fit between the oil pan rails of a standard deck height block without grinding away the sides of the block). Painted orange it looks just like a 396/454 though the decal on the breather claims 402.

As I stated earlier a longer stroke engine builds more torque than a similar bore shorter stroke engine. The only thing that keeps the longer stroke engine from reving as high and as fast as the shorter stroke motor is the reciprocating mass and added parasitic losses due to the pistons rubbing a greater distance and pushing harder upon the cylinder walls. If you are willing to strengthen the bottom end with stronger parts, run smaller piston skirts with lighter pressure on your piston rings, you could build a motor that would rev as fast and as high as the shorter stroke motor; it just would not live very long; and it would burn oil (a bad thing in a pump gas motor because it causes detonation in the combustion chamber beating up your light weight ring pack).

As I told you in my first reply to your question of which is the best BBC engine; the 540 has the best of both worlds (bore and stroke) that fits within a standard deck block. I also said to go large as soon as you decide to use a tall deck block, because every tall beck motor you see is at least a 632, with about half being a 705 cid or larger (you have to assume they are at least or they will eat your shorts).

Big Dave
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journeyman
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PostPosted: Fri Jul 13, 2007 11:25 am    Post subject: Reply with quote

Big Dave wrote:


As I stated earlier a longer stroke engine builds more torque than a similar bore shorter stroke engine. The only thing that keeps the longer stroke engine from reving as high and as fast as the shorter stroke motor is the reciprocating mass and added parasitic losses due to the pistons rubbing a greater distance and pushing harder upon the cylinder walls.
Big Dave


Don't mean to hijack, but wouldn't that mean that larger bore and shorter stroke would most always be desirable?

I do understand the reasoning for the parasitic losses and it makes sense. But what are the advantages of a longer stroke engine if they have higher losses in these areas (I know they produce more low end torque, but how is this explained from a technical point of view)?
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Big Dave
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PostPosted: Fri Jul 13, 2007 12:40 pm    Post subject: Reply with quote

journeyman wrote:
Don't mean to hijack, but wouldn't that mean that larger bore and shorter stroke would most always be desirable?


Only if you are going to rev the snot out of it. Long strokes make for torque, short strokes suffer from a lack of it. Torque is what is measured on the dyno. Horse power is a calculation of torque multiplied over time. The higher you rev a motor the more work it will produce for a given amount of time (think about it as getting a tenth of a horse power for every revolution; the more revolutions it can make in a minute the more horse power it makes).

journeyman wrote:
I do understand the reasoning for the parasitic losses and it makes sense. But what are the advantages of a longer stroke engine if they have higher losses in these areas (I know they produce more low end torque, but how is this explained from a technical point of view)?


It is torque that causes our car to move, to accelerate. It is the force that twists the axle. The more torque you have the harder the axle will twist and push the tire past the stationary ground. If you have gobs of torque and it all occurs at a low RPM, then you can utilize that torque to make your car pull away from a stop sign. Do you really want to launch your car from every stop sign at 8,600 RPM the way a Pro Stock car does. If you did how long would you be able to drive like that before a cop took notice of your driving style. A pro Stock car has gobs of high RPM horsepower that allows it to leave the line in a hurry, and by shifting at 10,000 RPM he keeps his motor in itís power band.

Any given motor will have a power band which was decided by the engine builder when he chooses the parts. A large intake port, with a mechanical roller cam that makes power from 7,500 to 10,000 RPM can make a lot of horse power. Depending upon how long the designer chose to make the stroke it can make lots of torque also, torque and horse power are not mutually exclusive.

I have a SBC 406 that makes 512 horse power and it has a very flat torque curve that "peaks" at 512 lbs./ft of torque. I could have gone for peak horse power but I knew I was going to be driving this car on the street. I built my BBC the same way, with 750 horse power (more or less as it has been dynoed three times and the power fluctuates by 40 horse), because of a long stroke it makes more torque than I can use; so much so that the car can not be driven any more on the street. Even with a set of 12" slicks I spin them through first and second gear (this is not the motors fault but mine for not setting up the chassis to handle this level of abuse).

A long rod, and with a long arm on the crank holds the piston at the top of the cylinder longer, than does a short stroke crank. Since gasoline burns quickly we want to harvest all of that energy as soon as possible in the combustion cycle. So the long stroke does that by holding the piston to the fire. In doing so it generates a tremendous down force on the crank which is converted into torque (that is the condensed version). Though gasoline burns quickly there is still some combustion forces generated on the power stroke so the longer we can hold that hot expanding gas in the cylinder the more power we can get out. Once again a long stroke means more time to get to the bottom of the power stroke compared to a short stroke. It is therefore more efficient with better BSFC numbers than a short stroke motor.

Big Dave
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journeyman
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PostPosted: Fri Jul 13, 2007 11:01 pm    Post subject: Reply with quote

Big Dave wrote:
journeyman wrote:
Don't mean to hijack, but wouldn't that mean that larger bore and shorter stroke would most always be desirable?


A long rod, and with a long arm on the crank holds the piston at the top of the cylinder longer, than does a short stroke crank. Since gasoline burns quickly we want to harvest all of that energy as soon as possible in the combustion cycle. So the long stroke does that by holding the piston to the fire. In doing so it generates a tremendous down force on the crank which is converted into torque (that is the condensed version). Though gasoline burns quickly there is still some combustion forces generated on the power stroke so the longer we can hold that hot expanding gas in the cylinder the more power we can get out. Once again a long stroke means more time to get to the bottom of the power stroke compared to a short stroke. It is therefore more efficient with better BSFC numbers than a short stroke motor.

Big Dave


Thanks, Dave, this is what I was looking for.

Quote:
So the long stroke does that by holding the piston to the fire. In doing so it generates a tremendous down force on the crank which is converted into torque (that is the condensed version).


Makes me think that this effect would cause more of the combustion heat (% of total combustion heat) to be turned into mechanical energy. Is that a valid assumption?

Interestingly, one of my 454's (1985) may need rebuilding soon. I don't have the money for it now, but I was toying (just toying, mind you) with the thought of using the longest stroke (+3/8"?) I could fit in the stock deck block, keeping the smallest bore.
I'm thinking this way as we rarely get above 3500 RPM and almost never surpass the 4K figure.
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wagon train
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PostPosted: Sat Jul 14, 2007 2:12 pm    Post subject: Reply with quote

For the Ford fan,before aftermarket heads were on every street corner.Building a long rod engine,makes the port seem effectively larger.It would only be a benefit with proper cam timing.In most cases people did not take it to the extreme and force the longest rod possible in there.Now that todays heads have velocity and flow that was impossible to obtain as little as ten years ago,there is no need to do that.
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Big Dave
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PostPosted: Sun Jul 15, 2007 11:25 am    Post subject: Reply with quote

There may not be a "need" to do it but it still makes free horse power (once you pay for the rod). With a longer rod costing the same as a shorter one it truly is free if you planned on changing the rod and piston anyway. Since pistons are a consumable (to me anyway) I never reuse them when building a motor, and since it costs less to replace a rod (thanks to all American jobs being shipped off shore to China) than to rebuild one; I replace rods and pistons in the next size larger bore.


Big Dave
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engine dr
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PostPosted: Tue Aug 07, 2007 9:51 am    Post subject: strocker Reply with quote

I CAN HERE THE EXPLOSION FROM HERE LOL,,,,,CANADA
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Knarley Darley
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PostPosted: Sun Dec 13, 2009 3:26 pm    Post subject: Reply with quote

Dawg. This thread will answer your question.
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hsutton
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PostPosted: Thu Jan 07, 2010 6:29 pm    Post subject: Reply with quote

13th round, I had a 454 and it consistently made more power than similar 427s. I noticed the most difference when we put the cars in high gear. The 454 would pull the 427s a couple mph in high gear. The rods in both engine are the same, stock for stock. The 454 pistons have the pin location raised by .120 of an inch, 1/2 the stroke increase.
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