Disadvantages of a long stroke
Originally Posted by black_knight
Yes, that would be a problem. What is the usual solution?
Originally Posted by LOnSLO
Either a taller deck (not yet available), or shorter rods, which makes piston speed even higher, and the piston skirt even shorter.
Originally Posted by black_knight
When you say rods in this context do you mean pushrods or other rods? And what is the piston skirt? Anyone have some links/pictures to help?
Originally Posted by black_knight
Yes, that would be a problem. What is the usual solution?
Mike
Last edited by SidewaysTA; Nov 30, 2004 at 03:34 PM.
On The Tree
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Originally Posted by black_knight
I am no expert, but I have heard enough to know that the LS1 is (hydraulic) valvetrain limited more than limited by piston velocity, even with a long stroke.
I was more talking about oil consumption and friction wear on the engine. And whatever else the problem is with > 4" strokes.
I was more talking about oil consumption and friction wear on the engine. And whatever else the problem is with > 4" strokes.
Originally Posted by LOnSLO
Either a taller deck (not yet available), or shorter rods, which makes piston speed even higher, and the piston skirt even shorter.
Reduced dwell at the top and bottom of stroke means faster piston speed in that area. It has no effect on actual speed up and down the bore.
On the deck spacer deal. It is VERY feasible. You can get .500 longer sleeves, or whatever you want to space them up, and just drop them in, iron or aluminum block. The tough part is making a billet deck spacer. It's been done before.
On the deck spacer deal. It is VERY feasible. You can get .500 longer sleeves, or whatever you want to space them up, and just drop them in, iron or aluminum block. The tough part is making a billet deck spacer. It's been done before.
Last edited by LOnSLO; Nov 30, 2004 at 08:24 PM.
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There's no need to rev an engine to 7k unless its a road race car. For 1/4 mile keeping the hp & tq in a shorter rpm band will make the car ET better. Remember a car making 450hp at 7,000rpm will lose in a 1/4 mile race against a car making only 400hp at 6,000rpm. With all things being equal. Rpm is time, and the longer it takes to rev the motor out the slower it will ET. Now on a road course, sure high revving motors are the way to go. All depends what you're aiming for.
Originally Posted by LOnSLO
Reduced dwell at the top and bottom of stroke means faster piston speed in that area. It has no effect on actual speed up and down the bore.
On the deck spacer deal. It is VERY feasible. You can get .500 longer sleeves, or whatever you want to space them up, and just drop them in, iron or aluminum block. The tough part is making a billet deck spacer. It's been done before.
On the deck spacer deal. It is VERY feasible. You can get .500 longer sleeves, or whatever you want to space them up, and just drop them in, iron or aluminum block. The tough part is making a billet deck spacer. It's been done before.
Piston Speed, very critical. Low rpm engines with large stroke can use Piston speed to cause the ram effect earlier which will make more power, but one has to understand this to take advantage of this.
Chris
Chris
Originally Posted by Cstraub
Piston Speed, very critical. Low rpm engines with large stroke can use Piston speed to cause the ram effect earlier which will make more power, but one has to understand this to take advantage of this.
Chris
Chris
Teching In
Joined: Aug 2003
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A change in rod length will cause the inverse affect on dwell at TDC than at BDC. In other words, longer dwell at TDC is shorter dwell at BDC and vice versa. Average piston speed in feet per minute is always (stroke x rpm)/6.
I'd love it a lot if someone can supply actual test data--not engineering theory--that shows that any of this matters. I won't claim to know anything at all, but I've done a lot of testing in this area and have found that, given identical engines of the same displacement, the bore, stroke, and rod length do not change the power curve at all regardless of the camshafts used.
DF
I'd love it a lot if someone can supply actual test data--not engineering theory--that shows that any of this matters. I won't claim to know anything at all, but I've done a lot of testing in this area and have found that, given identical engines of the same displacement, the bore, stroke, and rod length do not change the power curve at all regardless of the camshafts used.
DF
Last edited by Freiburger; Dec 2, 2004 at 11:30 AM.
Originally Posted by Freiburger
A change in rod length will cause the inverse affect on dwell at TDC than at BDC. In other words, longer dwell at TDC is shorter dwell at BDC and vice versa. Average piston speed in feet per minute is always (stroke x rpm)/6.
I'd love it a lot if someone can supply actual test data--not engineering theory--that shows that any of this matters. I won't claim to know anything at all, but I've done a lot of testing in this area and have found that, given identical engines of the same displacement, the bore, stroke, and rod length do not change the power curve at all regardless of the camshafts used.
DF
I'd love it a lot if someone can supply actual test data--not engineering theory--that shows that any of this matters. I won't claim to know anything at all, but I've done a lot of testing in this area and have found that, given identical engines of the same displacement, the bore, stroke, and rod length do not change the power curve at all regardless of the camshafts used.
DF
Hey David, doing a good job keep it up..
Saw that issue where you went for the top speed record...pretty cool. I wish I had the resource & time for something like that....
So how about an issue dedicated to LS1s? I'd buy it 'fo sho.
Saw that issue where you went for the top speed record...pretty cool. I wish I had the resource & time for something like that....
So how about an issue dedicated to LS1s? I'd buy it 'fo sho.
TECH Apprentice
Joined: Oct 2004
Posts: 329
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Greath idea, Darton sleeved with 1/2" "deck spacer". Make 500CI out
of a small block possible. Now you guys are pushing it...
If this happened intake spacer or different intake mani's will need to be made.
of a small block possible. Now you guys are pushing it...
If this happened intake spacer or different intake mani's will need to be made.
Originally Posted by grinder11
This is an interesting statement. I don't see how connecting rod length has anything whatsoever to do with piston speed, except in relation to how quickly it accelerates away from BDC & TDC, as well as the "dwell time' at both. Piston speed in SFPM is determined by R.P.M.'s and the length of the stroke, not rods, unless I am a victim of Alzheimers here. But don't ask, cuz I forgot already!! Anyhow, on a serious note, I have been a tool and diemaker for many years. What you just said was very interesting from the "taller deck" standpoint. Seeing as how I have not torn my motor down yet, and have only reading material, pictures, expert opinions such as those offered here, etc. to go by, I am not able to really know at this point, but I wonder if a "tall deck spacer" would be a feasible idea? I know this is off topic somewhat, but seeing as how our motors have sleeves, why couldn't it be a reasonable assumption that a 1/2" thick precision aluminum spacer be manufactured and have Darton make a 1/2" longer sleeve/ Just food for thought, but probably not edible!
Adkoonerstrator
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From: Deep in the seedy underworld of Koonerville
Originally Posted by Big-DEN
Greath idea, Darton sleeved with 1/2" "deck spacer". Make 500CI out
of a small block possible. Now you guys are pushing it...
If this happened intake spacer or different intake mani's will need to be made.
of a small block possible. Now you guys are pushing it...
If this happened intake spacer or different intake mani's will need to be made.
Originally Posted by XLR8NSS
I believe Steve @ Race-Eng talked about the possibility of making a deck spacer and sleeves to accomodate the extra height in another thread. He seems to think it is definately possible. Darton/Steve are also coming out with a 4.2" bore capable sleeve. 4.25" stroke and 4.2" bore would be 471ci.
But what about clearance? I never really paid attention, but can you comfortably take off the valve covers if they were 1/2" higher?