Anyone have proof that a long stroke makes torque?
These guys claim they could run 11:1 on this sort of combination with 87 octane (can't trust my wife to put in premium):
http://www.purplesagetradingpost.com...%20engine.html
Did they lie? Was it some sort of fluke?
http://www.purplesagetradingpost.com...%20engine.html
Did they lie? Was it some sort of fluke?
I gave you names and where to look. I lead you to water. It's up to you to drink.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
Reggogled to make sure I used pre-VVT numbers which I am finding for 2005 330tq for the 5.3 and 285 for the 4.8l making the torque number fall by a greater percentage than displacement.
...
The thing I still see you not paying attention to though is rpm, looks like a 4-500rpm difference in peak point, how much of that is stroke or displacement I couldn't say but it is part of the total package to be considered. The peak torque rpm is up on the L92 as well
...
The thing I still see you not paying attention to though is rpm, looks like a 4-500rpm difference in peak point, how much of that is stroke or displacement I couldn't say but it is part of the total package to be considered. The peak torque rpm is up on the L92 as well
In the article, I noticed that they talked about the differences in displacement making a difference in the numbers but they didn't blame it on the shorter stroke. I wonder why?
Short stroke engines don't HAVE to make torque at higher RPMs. The old '66 283 (3.875 x 3.00) with 2bbl made max torque (285 ft/lbs) at 2400 RPM. The Chevy big block 348 in 1961 with a bore/stroke of 4.125 x 3.25 (sound familiar?) made max torque (355 ft/lbs) at 2800 RPM. The 1969 truck 327 (4.00 x 3.25) made max torque (320 ft/lbs) at 2400 RPM
The DZ302 makes it's numbers in the clouds because that's how it was designed, with a hot cam and dual 4bbl carbs. BTW, it maxed out at 290@4200 kinda like an LS 5.3L truck motor.
BTW, I know the old torque numbers were "optimistic." The point is the where these engines hit the peak of their torque curve. The definition of RPM hasn't changed over the years.
Was I using pre-VVT numbers (no)? I go through the effort to make an apples to apples comparison and then you start talking about peaches.
In the article, I noticed that they talked about the differences in displacement making a difference in the numbers but they didn't blame it on the shorter stroke. I wonder why?
Short stroke engines don't HAVE to make torque at higher RPMs. The old '66 283 (3.875 x 3.00) with 2bbl made max torque (285 ft/lbs) at 2400 RPM. The Chevy big block 348 in 1961 with a bore/stroke of 4.125 x 3.25 (sound familiar?) made max torque (355 ft/lbs) at 2800 RPM. The 1969 truck 327 (4.00 x 3.25) made max torque (320 ft/lbs) at 2400 RPM
The DZ302 makes it's numbers in the clouds because that's how it was designed, with a hot cam and dual 4bbl carbs. BTW, it maxed out at 290@4200 kinda like an LS 5.3L truck motor.
BTW, I know the old torque numbers were "optimistic." The point is the where these engines hit the peak of their torque curve. The definition of RPM hasn't changed over the years.
In the article, I noticed that they talked about the differences in displacement making a difference in the numbers but they didn't blame it on the shorter stroke. I wonder why?
Short stroke engines don't HAVE to make torque at higher RPMs. The old '66 283 (3.875 x 3.00) with 2bbl made max torque (285 ft/lbs) at 2400 RPM. The Chevy big block 348 in 1961 with a bore/stroke of 4.125 x 3.25 (sound familiar?) made max torque (355 ft/lbs) at 2800 RPM. The 1969 truck 327 (4.00 x 3.25) made max torque (320 ft/lbs) at 2400 RPM
The DZ302 makes it's numbers in the clouds because that's how it was designed, with a hot cam and dual 4bbl carbs. BTW, it maxed out at 290@4200 kinda like an LS 5.3L truck motor.
BTW, I know the old torque numbers were "optimistic." The point is the where these engines hit the peak of their torque curve. The definition of RPM hasn't changed over the years.
1960's cars were saddled with 3/4speed transmissions and had to be powered/geared/etc to work with that technology. You could argue torque production needed to be lower in order to work with a gearset to achieve reasonable all around performance. A DZ 302 backed up by a 6 speed manual or auto would behave a lot differently.
Any engine you built with a 4.00 ish bore and 3.62 ish stroke based on an SBC platform will not behave like a similar LS based approach just becasue they have a similar bore and stroke. Way too many variable involved.
I do know who has run the tests you seek. I am sure the OEM's have played around with all of these variables, but it is proprietary information. I doubt that any off the shops or individuals have deep enough pockets to run this level of R&D. Especially when changes are probably only in the low single digits on a percentage basis.
You can probably get 99% of what you want from a 5.3 with a aftermarket cam with a torque bias, and spen less than half of your plan. Won't be nearly as sexy, but a heck of a lot less trouble to figure out.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
I am not trying to be rude, but I think you are clouding the issue by comparing SBC based engine with LS based engines solely based on bore and stroke. There are far to many variables to make any reasonable comparison. 2/4/8 barells of carbueration vs Port injection, intake flow rates, heads (crappy 23 degree heads. vs LS heads), cam differences, and whatever else we can dig up.
1960's cars were saddled with 3/4speed transmissions and had to be powered/geared/etc to work with that technology. You could argue torque production needed to be lower in order to work with a gearset to achieve reasonable all around performance. A DZ 302 backed up by a 6 speed manual or auto would behave a lot differently.
Any engine you built with a 4.00 ish bore and 3.62 ish stroke based on an SBC platform will not behave like a similar LS based approach just becasue they have a similar bore and stroke. Way too many variable involved.
I do know who has run the tests you seek. I am sure the OEM's have played around with all of these variables, but it is proprietary information. I doubt that any off the shops or individuals have deep enough pockets to run this level of R&D. Especially when changes are probably only in the low single digits on a percentage basis.
You can probably get 99% of what you want from a 5.3 with a aftermarket cam with a torque bias, and spen less than half of your plan. Won't be nearly as sexy, but a heck of a lot less trouble to figure out.
1960's cars were saddled with 3/4speed transmissions and had to be powered/geared/etc to work with that technology. You could argue torque production needed to be lower in order to work with a gearset to achieve reasonable all around performance. A DZ 302 backed up by a 6 speed manual or auto would behave a lot differently.
Any engine you built with a 4.00 ish bore and 3.62 ish stroke based on an SBC platform will not behave like a similar LS based approach just becasue they have a similar bore and stroke. Way too many variable involved.
I do know who has run the tests you seek. I am sure the OEM's have played around with all of these variables, but it is proprietary information. I doubt that any off the shops or individuals have deep enough pockets to run this level of R&D. Especially when changes are probably only in the low single digits on a percentage basis.
You can probably get 99% of what you want from a 5.3 with a aftermarket cam with a torque bias, and spen less than half of your plan. Won't be nearly as sexy, but a heck of a lot less trouble to figure out.
Yes, I could get what I want with a 6.0 or 6.2. I have my doubts that I could get what I want from a 5.3. Building an engine is a big investment even when you go cheap. The worst investment is the one that doesn't make you happy when you are done. If it takes 5k instead of 3k and you got what you want, you made a good deal.
Teching In
Joined: Sep 2013
Posts: 43
Likes: 0
From: Straya
The common and intuitive idea that long stroke small bore engines produce more torque due to increased leverage is wrong. For a given displacement and given cylinder pressure, a long stroke does increase leverage; but a smaller bore means a smaller piston on which the combustion pressure is applied, and therefore less force (pressure x area), so it's a wash.
A long stroke does, however, increase piston speed for a given rpm, which promotes better cylinder filling (volumetric efficiency) and mixture swirl. The small bore is also less likely to knock under high load low rpm conditions because the combustion area is more compact. These effects all help increase torque.
A long stroke does, however, increase piston speed for a given rpm, which promotes better cylinder filling (volumetric efficiency) and mixture swirl. The small bore is also less likely to knock under high load low rpm conditions because the combustion area is more compact. These effects all help increase torque.
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
Back in 2003 my friend bought a brand new silverado. We took both the 4.8 and the 5.3 for a ride up a big hill and the 5.3 performed much better.You could really feal the power difference going up the same hill. He bought the one with the 5.3.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
More displacement always wins in NA engines with all other variables being equal.
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On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
The common and intuitive idea that long stroke small bore engines produce more torque due to increased leverage is wrong. For a given displacement and given cylinder pressure, a long stroke does increase leverage; but a smaller bore means a smaller piston on which the combustion pressure is applied, and therefore less force (pressure x area), so it's a wash.
A long stroke does, however, increase piston speed for a given rpm, which promotes better cylinder filling (volumetric efficiency) and mixture swirl. The small bore is also less likely to knock under high load low rpm conditions because the combustion area is more compact. These effects all help increase torque.
A long stroke does, however, increase piston speed for a given rpm, which promotes better cylinder filling (volumetric efficiency) and mixture swirl. The small bore is also less likely to knock under high load low rpm conditions because the combustion area is more compact. These effects all help increase torque.
I'm not clouding the issue at all. The generalization stated was that short strokes CAN'T produce low end torque. This should be true of any engine if it is true at all. I gave a list of short stroke engines that made peak torque below 3k. It is a little ironic that none of the factory LS engines with their long stroke make peak torque at less than 4k.
For example my cammed LS1 maked peak torque at 5000 rpms. it is not like it is making 100 tf/lbs off idle. It is over 300 ft/lbs by 2400. It just carries it across the band.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
Respectfully, it does cloud the issue. Overlay the curves. Peak is immaterial. The LS series head design is superior to just about any head in the 1960's. It is not that they don't make low end torque, its that they don't nosedive as rpms build. Those 60's motors peaked that low becasue they were sucking wind at elevated rpms.
For example my cammed LS1 maked peak torque at 5000 rpms. it is not like it is making 100 tf/lbs off idle. It is over 300 ft/lbs by 2400. It just carries it across the band.
For example my cammed LS1 maked peak torque at 5000 rpms. it is not like it is making 100 tf/lbs off idle. It is over 300 ft/lbs by 2400. It just carries it across the band.
http://www.purplesagetradingpost.com...%20engine.html
On The Tree
Joined: Jun 2010
Posts: 192
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Respectfully, it does cloud the issue. Overlay the curves. Peak is immaterial. The LS series head design is superior to just about any head in the 1960's. It is not that they don't make low end torque, its that they don't nosedive as rpms build. Those 60's motors peaked that low becasue they were sucking wind at elevated rpms.
For example my cammed LS1 maked peak torque at 5000 rpms. it is not like it is making 100 tf/lbs off idle. It is over 300 ft/lbs by 2400. It just carries it across the band.
For example my cammed LS1 maked peak torque at 5000 rpms. it is not like it is making 100 tf/lbs off idle. It is over 300 ft/lbs by 2400. It just carries it across the band.
My big block made PEAK torque at 5500...... Is was a mild 468 10:1 compression with a 229I 236E @.050 duration cam it was in a 69 vette and had the tri-power on it peak of 543ft/lbs@5500 but it had 478@3000 and 499@6000 it is about combo
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
Was I using pre-VVT numbers (no)? I go through the effort to make an apples to apples comparison and then you start talking about peaches.
In the article, I noticed that they talked about the differences in displacement making a difference in the numbers but they didn't blame it on the shorter stroke. I wonder why?
Short stroke engines don't HAVE to make torque at higher RPMs. The old '66 283 (3.875 x 3.00) with 2bbl made max torque (285 ft/lbs) at 2400 RPM. The Chevy big block 348 in 1961 with a bore/stroke of 4.125 x 3.25 (sound familiar?) made max torque (355 ft/lbs) at 2800 RPM. The 1969 truck 327 (4.00 x 3.25) made max torque (320 ft/lbs) at 2400 RPM
The DZ302 makes it's numbers in the clouds because that's how it was designed, with a hot cam and dual 4bbl carbs. BTW, it maxed out at 290@4200 kinda like an LS 5.3L truck motor.
BTW, I know the old torque numbers were "optimistic." The point is the where these engines hit the peak of their torque curve. The definition of RPM hasn't changed over the years.
In the article, I noticed that they talked about the differences in displacement making a difference in the numbers but they didn't blame it on the shorter stroke. I wonder why?
Short stroke engines don't HAVE to make torque at higher RPMs. The old '66 283 (3.875 x 3.00) with 2bbl made max torque (285 ft/lbs) at 2400 RPM. The Chevy big block 348 in 1961 with a bore/stroke of 4.125 x 3.25 (sound familiar?) made max torque (355 ft/lbs) at 2800 RPM. The 1969 truck 327 (4.00 x 3.25) made max torque (320 ft/lbs) at 2400 RPM
The DZ302 makes it's numbers in the clouds because that's how it was designed, with a hot cam and dual 4bbl carbs. BTW, it maxed out at 290@4200 kinda like an LS 5.3L truck motor.
BTW, I know the old torque numbers were "optimistic." The point is the where these engines hit the peak of their torque curve. The definition of RPM hasn't changed over the years.
.050 and cylinder heads that flowed nowhere near 200 cfm so while you're right that they did peak low....that was by design/restriction. Also factor that
those were gross ratings not net.
Lastly the 302 DZ engine made way closer to 400 horsepower at 7200....the
General's rating was quite a joke !!!!
I'm not clouding the issue at all. The generalization stated was that short strokes CAN'T produce low end torque. This should be true of any engine if it is true at all. I gave a list of short stroke engines that made peak torque below 3k. It is a little ironic that none of the factory LS engines with their long stroke make peak torque at less than 4k.
We had the opportunity to play with one in high school. It was tired and still made just a hair over 375 on the engine dyno. After a head swap to a set of AFRs, a cam/lifter change, and a set of long tubes with the card re-jetted (short block was untouched minus a polish on the crank, new bearings, and a hone with new rings) it made 502 on that same engine dyno. Badass little engines. If I remember right, the duration was huge, like a 250+. Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
Thanks for the input both pro/con I'll let you know what I've done and how it turns out. Time to upgrade the desktop dyno software and play with valve train combinations to find what I want. Before anyone says anything, I know the numbers in DD aren't realistic but they seem sufficient to make relative comparisons.
Thread Starter
On The Tree
Joined: Jan 2014
Posts: 136
Likes: 1
From: Nebraska
. The biggest down side is I have to buy custom pistons but Wiseco says it's no problem and not that much more than stock pistons. If I drop down to 4.070, I can get off the shelf pistons.