gains from stroking
11-03-2010, 10:31 PM
#21
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hmm confused to whom is him ha dont matter here is one of my threads from the other day thats how i got my block just waiting for the money to allow for stroker kit and the un enending list of parts to support it. hope the build goes good.
https://ls1tech.com/forums/generatio...cast-iron.html
https://ls1tech.com/forums/generatio...cast-iron.html
11-04-2010, 11:41 AM
#22
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If you're already getting a peak hp lower than your rev limit, you won't make more peak hp USING THE SAME PARTS. You will make the same power, but shift the power curve to a lower rpm range. If you up the head/cam intake package to suit the extra cubes, you can keep the same basic power curve, but stronger overall.
The extra compression that can come from stroking it would help power, however.
Torque numbers follow the same stuff as the hp, depends if you're matching parts for the extra cubes.
If you like where your power is, but want more overall, cam it with the extra stroke. Heads too if $$ lets you.
The extra compression that can come from stroking it would help power, however.
Torque numbers follow the same stuff as the hp, depends if you're matching parts for the extra cubes.
If you like where your power is, but want more overall, cam it with the extra stroke. Heads too if $$ lets you.
Last edited by treyZ28; 11-04-2010 at 02:00 PM. Reason: for some reason, the split infinitive there was bothering me.
11-04-2010, 04:51 PM
#23
If you're already getting a peak hp lower than your rev limit, you won't make more peak hp USING THE SAME PARTS. You will make the same power, but shift the power curve to a lower rpm range. If you up the head/cam intake package to suit the extra cubes, you can keep the same basic power curve, but stronger overall.
The extra compression that can come from stroking it would help power, however.
Torque numbers follow the same stuff as the hp, depends if you're matching parts for the extra cubes.
If you like where your power is, but want more overall, cam it with the extra stroke. Heads too if $$ lets you.
The extra compression that can come from stroking it would help power, however.
Torque numbers follow the same stuff as the hp, depends if you're matching parts for the extra cubes.
If you like where your power is, but want more overall, cam it with the extra stroke. Heads too if $$ lets you.
This is way over simplified but stroke makes TQ and bore makes HP...
11-07-2010, 04:38 PM
#25
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Guys this is absolutely true. Think of it this way..... If the only thing you change is the crank, rods, and pistons (but maintain same SCR) why will HP go up??? It won't but as rizzle said it will just shift the same curve to lower RPM's because of the extra stroke....
This is way over simplified but stroke makes TQ and bore makes HP...
This is way over simplified but stroke makes TQ and bore makes HP...
No it's not. Because you have ~35-40 more cubic inches of displacement, even if the heads are the same.
11-07-2010, 07:06 PM
#26
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Ok so think of it this way you are spinning the crank around with a 1 foot rod and try and spin it 600 revolutions a minute ok now try to do it with a 3 foot rod which takes less work to spin it around you can get it going faster with that longer stroke without exerting more force this is probably a horrible example ha but just look it up on google its physics
11-11-2010, 08:07 PM
#29
your exhaust is restrictive for that big of motor.with a better flowing exhaust and a EPS cam,and a good converter you can make 500 hp/tq.you will break a stock rear end.you could run 9.90 with every thing right and tuned.
11-12-2010, 03:44 AM
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You have a bigger pressure drop (more force) sucking in air. Unless you have something like an 86 TBI, it's going to make more power. Not worth the bang for the buck, but you're crazy if you think a 383 LSx won't make more power than a 346 (?) LSx
11-12-2010, 09:39 AM
#32
You are restricted on air, otherwise power would never peak.
383 Engine Dyno Results (graphs included)
It's not crazy, it's just counterintuitive. A given cross section of area will only be able to flow a given volume of air per minute. After this point, it doesn't matter how much negative pressure you put to it, it simply will not flow any more air. A bigger engine will just reach this point sooner with the same induction package as a smaller engine.
383 Engine Dyno Results (graphs included)
...the motor that was previously in my car (the stock short AFR 224/228 combination you guys have read tons of info on) on the very same dyno I recently completed testing the 383 on, put down 550 HP / 482 Ft/lbs.
FIRST ROUND OF TESTING
Essentially the exact same combination as the 346 in my car and whose flywheel dyno results I shared with you above (550 HP/ 482 TQ), the ONLY difference being the larger 383 displacement shortblock.
Final Results 552 HP / 522 TQ
Summary:
The results were inline with what I expected...I was questioning whether the larger engine with the same induction/small cam might make less peak power and was glad to see it came in exactly the same. Big increase in TQ was a no-brainer.
FIRST ROUND OF TESTING
Essentially the exact same combination as the 346 in my car and whose flywheel dyno results I shared with you above (550 HP/ 482 TQ), the ONLY difference being the larger 383 displacement shortblock.
Final Results 552 HP / 522 TQ
Summary:
The results were inline with what I expected...I was questioning whether the larger engine with the same induction/small cam might make less peak power and was glad to see it came in exactly the same. Big increase in TQ was a no-brainer.
It's not crazy, it's just counterintuitive. A given cross section of area will only be able to flow a given volume of air per minute. After this point, it doesn't matter how much negative pressure you put to it, it simply will not flow any more air. A bigger engine will just reach this point sooner with the same induction package as a smaller engine.
11-12-2010, 10:32 AM
#33
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Thanks for the link, but I don't think it's really a fair assessment when it's a 550hp engine using those heads (and there is ~5-10hp difference if the compression ratios were equal). I don't doubt that for a minute.
Like I said "Unless you have something like an 86 TBI, it's going to make more power. " 550hp through that setup is probably just as restricted as an 86 TBI (relatively speaking, obviously the TBI is more restrictive in absolute terms).
For a stock LSX engine or bolt on, stroking it will increase power. Again, not worth the bang for the buck compared to top end upgrades, but there will be more peak power.
Like I said "Unless you have something like an 86 TBI, it's going to make more power. " 550hp through that setup is probably just as restricted as an 86 TBI (relatively speaking, obviously the TBI is more restrictive in absolute terms).
For a stock LSX engine or bolt on, stroking it will increase power. Again, not worth the bang for the buck compared to top end upgrades, but there will be more peak power.
11-12-2010, 12:07 PM
#35
Thanks for the link, but I don't think it's really a fair assessment when it's a 550hp engine using those heads (and there is ~5-10hp difference if the compression ratios were equal). I don't doubt that for a minute.
Like I said "Unless you have something like an 86 TBI, it's going to make more power. " 550hp through that setup is probably just as restricted as an 86 TBI (relatively speaking, obviously the TBI is more restrictive in absolute terms).
For a stock LSX engine or bolt on, stroking it will increase power. Again, not worth the bang for the buck compared to top end upgrades, but there will be more peak power.
Like I said "Unless you have something like an 86 TBI, it's going to make more power. " 550hp through that setup is probably just as restricted as an 86 TBI (relatively speaking, obviously the TBI is more restrictive in absolute terms).
For a stock LSX engine or bolt on, stroking it will increase power. Again, not worth the bang for the buck compared to top end upgrades, but there will be more peak power.
Your 5-10hp estimate is pretty generous if you're still referring to peak numbers. 5-10ft-lbs sure, but not 5-10hp. I'd say 5hp would be pushing it. Peak Hp numbers are dictated by the limits of the induction system, to include camshaft timing. The displacement that the induction system feeds dictate where that peak happens.
Now I think it's your turn to provide evidence. Where has it been shown that you can increase the displacement of the engine with the same parts, and the peak RPM stays the same?
11-12-2010, 04:45 PM
#36
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How is that not a fair assessment? That's what we're talking about here right? That's a 347ci engine stroked to 383ci with the same induction parts and it makes roughly the same HP but at a lower RPM. Even if it were stock parts, you would still see the same trend occur. You're the one that said that was not true and should be disregarded, yet here is empirical evidence to say otherwise.
Your 5-10hp estimate is pretty generous if you're still referring to peak numbers. 5-10ft-lbs sure, but not 5-10hp. I'd say 5hp would be pushing it. Peak Hp numbers are dictated by the limits of the induction system, to include camshaft timing. The displacement that the induction system feeds dictate where that peak happens.
Now I think it's your turn to provide evidence. Where has it been shown that you can increase the displacement of the engine with the same parts, and the peak RPM stays the same?
Your 5-10hp estimate is pretty generous if you're still referring to peak numbers. 5-10ft-lbs sure, but not 5-10hp. I'd say 5hp would be pushing it. Peak Hp numbers are dictated by the limits of the induction system, to include camshaft timing. The displacement that the induction system feeds dictate where that peak happens.
Now I think it's your turn to provide evidence. Where has it been shown that you can increase the displacement of the engine with the same parts, and the peak RPM stays the same?
11-12-2010, 05:24 PM
#37
If the stroke gains displacement and all other factors remain the same, the horsepower should increase. If you are limiting the setup by the amount of air you can draw in (heads and cam) then you are fouling the test's results.
A 383 will always make more power than a 346 if they are tuned to take advantage of the extra displacement. Saying that more stroke = more torque and the same HP is like saying more bore = same torque and more HP. It doesn't make sense logically or mathematically. Lets say we have 2 engines with the same displacement, one oversquare and one undersquare. More stroke = more mechanical advantage on the crank = more torque = more horsepower (they go hand in hand). More bore = more pressure on the piston from more surface area = more torque = more horsepower. The driving characteristics will be slightly different because of cylinder filling and other factors, but the engines will produce roughly the same power and torque because they have the same displacement.
A 383 will always make more power than a 346 if they are tuned to take advantage of the extra displacement. Saying that more stroke = more torque and the same HP is like saying more bore = same torque and more HP. It doesn't make sense logically or mathematically. Lets say we have 2 engines with the same displacement, one oversquare and one undersquare. More stroke = more mechanical advantage on the crank = more torque = more horsepower (they go hand in hand). More bore = more pressure on the piston from more surface area = more torque = more horsepower. The driving characteristics will be slightly different because of cylinder filling and other factors, but the engines will produce roughly the same power and torque because they have the same displacement.
11-12-2010, 05:42 PM
#38
If the stroke gains displacement and all other factors remain the same, the horsepower should increase. If you are limiting the setup by the amount of air you can draw in (heads and cam) then you are fouling the test's results.
A 383 will always make more power than a 346 if they are tuned to take advantage of the extra displacement. Saying that more stroke = more torque and the same HP is like saying more bore = same torque and more HP. It doesn't make sense logically or mathematically. Lets say we have 2 engines with the same displacement, one oversquare and one undersquare. More stroke = more mechanical advantage on the crank = more torque = more horsepower (they go hand in hand). More bore = more pressure on the piston from more surface area = more torque = more horsepower. The driving characteristics will be slightly different because of cylinder filling and other factors, but the engines will produce roughly the same power and torque because they have the same displacement.
A 383 will always make more power than a 346 if they are tuned to take advantage of the extra displacement. Saying that more stroke = more torque and the same HP is like saying more bore = same torque and more HP. It doesn't make sense logically or mathematically. Lets say we have 2 engines with the same displacement, one oversquare and one undersquare. More stroke = more mechanical advantage on the crank = more torque = more horsepower (they go hand in hand). More bore = more pressure on the piston from more surface area = more torque = more horsepower. The driving characteristics will be slightly different because of cylinder filling and other factors, but the engines will produce roughly the same power and torque because they have the same displacement.
Last edited by Darkman; 11-12-2010 at 06:11 PM. Reason: spelling
11-12-2010, 05:58 PM
#39
A 383 will always make more power than a 346 if they are tuned to take advantage of the extra displacement. Saying that more stroke = more torque and the same HP is like saying more bore = same torque and more HP. It doesn't make sense logically or mathematically. Lets say we have 2 engines with the same displacement, one oversquare and one undersquare. More stroke = more mechanical advantage on the crank = more torque = more horsepower (they go hand in hand). More bore = more pressure on the piston from more surface area = more torque = more horsepower. The driving characteristics will be slightly different because of cylinder filling and other factors, but the engines will produce roughly the same power and torque because they have the same displacement.
To take advantage of the larger displacement, you must increase the airflow capabilities of the induction package to shift the TQ curve back to the right. Without doing that, you still make more overall power and torque, but the peak power stays almost exactly the same.
11-12-2010, 05:58 PM
#40
More torque does not necessarily mean more horsepower. Horsepower is a function of torque and rpm, so when torque increases but the associated rpm declines horsepower can increase, decrease, or stay the same depending on the degree of change in the two vaiables (TQ and rpm).
