Any DeStrokers or Short Strokers out there with 4.125 bore
09-22-2007, 02:24 AM
#21
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an ideal engine for me is a 4.5" bore and 3.5" stroke with 6, 8 or 12 cylinders 
Id say thats a good size bore and a hemispherical combustion chamber, not wedge. to allow larger valves area. and 3.5" stroke should safely rev to 8000 - 8500rpm.
I know a 4" stroke shouldnt probably go past 7grand due to mean piston speed.
Id say thats a good size bore and a hemispherical combustion chamber, not wedge. to allow larger valves area. and 3.5" stroke should safely rev to 8000 - 8500rpm.
I know a 4" stroke shouldnt probably go past 7grand due to mean piston speed.
09-22-2007, 08:12 AM
#22
TECH Fanatic
Originally Posted by racecar
A short stroke may make good peak power but not have low end torque. I think what LT is trying to say is this may work in a road race car when you apex the corner at 3500rpm, do you want max toque then, no I don't have my foot to the floor until I'm around the corner and hit 4200. So a short stroker may work, it will hit the power band when you need it. It worked in the TransAM series. 4.06 bore x 3.0 stroke.
Short strokers work if you are looking for big peak power and don't need the low end torque. This is a good combination in a light car.
Short strokers work if you are looking for big peak power and don't need the low end torque. This is a good combination in a light car.
You could very well do a big-bore short stroke engine with long intake runners, proper heads and valve timing and make great torque per cubic inch in the low-medium rpm range. You also configure a long stroke engine to make the same torque per cubic inch in the same rpm range. The way the air is gotten into and out of the engine sdetermines the shape of the torque curve and also the amount of torque and power the engine makes. The larger displacement engine could make more of everything.
Longer strokes do directly relate to piston speed and friction losses, so short strokes may actually get more to the flywheel.
Older Trans Am and current Daytona Prototype (GM) 5L engines both used the largest bores and shortest strokes they legally (or mechanically) could. Today they have rpm limits imposed by the rules, not the mechanical bits.
The production LS7 has a 4 inch stroke and a 7000 rpm factory rev limit. There are a number of them running well over that, but iit's difficult to get enough air to push the NA power peak much past the mid 7s.
Personally I'd rather see/hear a 7+L sheetmetal intake LS-based engine spinning in the mid 7s and making over 2 hp/cube than a 5 or 5.7 makin' the same hp/cube @ 8. The extra couple hundred lb-ft and horses of the big one wouldn't be all bad either.
"A good big guy can beat up a good little guy 'most every time."...Maverick's Pappy
09-22-2007, 08:53 AM
#23
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Is it generally true that for the same displacement that undersquare is less susceptible to detonation than oversquare? or is this question too far off topic?
Originally Posted by Old SStroker
FWIW: I guess most folks consider 'destroking" as decreasing the stock stroke (or whatever you are running), not comparing it to the bore as in "bore/stroke ratio". B/S >1 (Bore larger than stroke) is considered "oversquare", B/S = 1 (same Bore and stroke) is considered "square" and B/S < 1 (Bore smaller than stroke) is considered "undersquare".
Current wisdom for endurance engines and some "gernades" like Pro Stock (with displacement limits) is as much oversquare as you can get. F1 engines have B/S > 2, Cup B/S > 1.28, and PS B/S >1.3 or thereabouts. Original LS7-based 5.7L CTSV-R B/S>1.25. I think they pushed them back to LS6 architecture a couple of years ago so they may now be B/S ~1.07. The Daytona Prototypes with 5L LS6-base engines are B/S~1.2 because they are limited in bore size by the rules.
Current wisdom for endurance engines and some "gernades" like Pro Stock (with displacement limits) is as much oversquare as you can get. F1 engines have B/S > 2, Cup B/S > 1.28, and PS B/S >1.3 or thereabouts. Original LS7-based 5.7L CTSV-R B/S>1.25. I think they pushed them back to LS6 architecture a couple of years ago so they may now be B/S ~1.07. The Daytona Prototypes with 5L LS6-base engines are B/S~1.2 because they are limited in bore size by the rules.
09-22-2007, 09:13 AM
#24
TECH Fanatic
Originally Posted by billc5
Is it generally true that for the same displacement that undersquare is less susceptible to detonation than oversquare? or is this question too far off topic?
Modern OEM engines may be less oversquare for a number of reasons. Resistance to detonation may be one of them, but not necessarily the driving reason.
Good question, IMO. I think it's OT, but I've never been invited to be a moderator here.
09-22-2007, 11:28 AM
#25
FormerVendor
Originally Posted by billc5
Is it generally true that for the same displacement that undersquare is less susceptible to detonation than oversquare? or is this question too far off topic?
I will take more power in the form of the bigger bore every time though and I'll also run the bigger stroke as well if there are no rules stopping me. I don't know that it's a huge difference in the detonation department either. Engine just get inefficient and gross when you make the stroke too short in many ways but if all you are after is hp per inch then it's the way to go.
If you want maximum total hp and efficiency out of a given engine and bore size then run all the stroke you can reasonably fit without screwing up the piston etc.
Anotherwords big bore is good while short stroke is bad for power but the bore is more important than stroke in the over all picture towards making the more power. The best is when you run the most you can of them both.
09-24-2007, 09:18 AM
#26
Originally Posted by racecar
A short stroke may make good peak power but not have low end torque. I think what LT is trying to say is this may work in a road race car when you apex the corner at 3500rpm, do you want max toque then, no I don't have my foot to the floor until I'm around the corner and hit 4200. So a short stroker may work, it will hit the power band when you need it. It worked in the TransAM series. 4.06 bore x 3.0 stroke.
Short strokers work if you are looking for big peak power and don't need the low end torque. This is a good combination in a light car.
Short strokers work if you are looking for big peak power and don't need the low end torque. This is a good combination in a light car.
As I sit here and think about it, I honestly cannot think of one single engine that was destroked without a displacement limit on the engine. Everyone that had a unlimited displacement ran as big of a ci as they could. Am I missing a racing series???
09-24-2007, 02:26 PM
#27
destoke enignes means longer rods most the time and there is alot good done buy running longer rods..less force on the piston skirt and bore on the block.which cuts done in friction.
u tend to get better rod ratios also buy useing this and can run good comp height on pistons.
i am a big fan of destoked engines..the oh well u have to rev higher to make just as much hp as what u would make with a stroker engine is B.S.that is all in the cam and if u design a cam ment for a destroke application u can spin it to the same rpm as a stroker engine and make the same power at peak rpm if done right.
i've designed engine in the 447ci range that would spin higher then a 355 engine(4.155 bore and 3.27 stroke) and make about the same power.
also i like the fact that a destroked engine most of the time has a wider power band.
u tend to get better rod ratios also buy useing this and can run good comp height on pistons.
i am a big fan of destoked engines..the oh well u have to rev higher to make just as much hp as what u would make with a stroker engine is B.S.that is all in the cam and if u design a cam ment for a destroke application u can spin it to the same rpm as a stroker engine and make the same power at peak rpm if done right.
i've designed engine in the 447ci range that would spin higher then a 355 engine(4.155 bore and 3.27 stroke) and make about the same power.
also i like the fact that a destroked engine most of the time has a wider power band.
09-24-2007, 04:06 PM
#29
Originally Posted by suicidal racing
destoke enignes means longer rods most the time and there is alot good done buy running longer rods..less force on the piston skirt and bore on the block.which cuts done in friction.
u tend to get better rod ratios also buy useing this and can run good comp height on pistons.
i am a big fan of destoked engines..the oh well u have to rev higher to make just as much hp as what u would make with a stroker engine is B.S.that is all in the cam and if u design a cam ment for a destroke application u can spin it to the same rpm as a stroker engine and make the same power at peak rpm if done right.
i've designed engine in the 447ci range that would spin higher then a 355 engine(4.155 bore and 3.27 stroke) and make about the same power.
also i like the fact that a destroked engine most of the time has a wider power band.
u tend to get better rod ratios also buy useing this and can run good comp height on pistons.
i am a big fan of destoked engines..the oh well u have to rev higher to make just as much hp as what u would make with a stroker engine is B.S.that is all in the cam and if u design a cam ment for a destroke application u can spin it to the same rpm as a stroker engine and make the same power at peak rpm if done right.
i've designed engine in the 447ci range that would spin higher then a 355 engine(4.155 bore and 3.27 stroke) and make about the same power.
also i like the fact that a destroked engine most of the time has a wider power band.
09-24-2007, 05:46 PM
#30
TECH Fanatic
Originally Posted by suicidal racing
destoke enignes means longer rods most the time and there is alot good done buy running longer rods..less force on the piston skirt and bore on the block.which cuts done in friction.
u tend to get better rod ratios also buy useing this and can run good comp height on pistons.
i am a big fan of destoked engines..the oh well u have to rev higher to make just as much hp as what u would make with a stroker engine is B.S.that is all in the cam and if u design a cam ment for a destroke application u can spin it to the same rpm as a stroker engine and make the same power at peak rpm if done right.
i've designed engine in the 447ci range that would spin higher then a 355 engine(4.155 bore and 3.27 stroke) and make about the same power.
also i like the fact that a destroked engine most of the time has a wider power band.
u tend to get better rod ratios also buy useing this and can run good comp height on pistons.
i am a big fan of destoked engines..the oh well u have to rev higher to make just as much hp as what u would make with a stroker engine is B.S.that is all in the cam and if u design a cam ment for a destroke application u can spin it to the same rpm as a stroker engine and make the same power at peak rpm if done right.
i've designed engine in the 447ci range that would spin higher then a 355 engine(4.155 bore and 3.27 stroke) and make about the same power.
also i like the fact that a destroked engine most of the time has a wider power band.
You can judge how well any engine processes air and fuel by looking at the torque produced per cubic inch at power peak rpm. That's agood definitionof Brake Mean Effective Pressure or BMEP.
Look @600 fwhp @ 6500 for both a 447 and a 355. The BMEP of the 355 is about 205 psi which is darn good. You could make this a driveable engine with killer heads, the right intake and exhaust lengths and the right cam.
The BMEP for the 447 @6500 is about 164 psi. Almost any swingin' Richard can do 164 BMEP. If you made 550 fwhp from a stock LS7 @ 6200, which takes maybe headers and a tiny cam change , you'd be @ 164 psi BMEP.
So what's your point?
09-24-2007, 11:07 PM
#31
them engines where all out n/a engines the 447 from all the math and what it showed on paper was peaking around 9762 rpms and lil over 1008hp
the 355 shows around 995hp at 8786 rpms.
the 2 cams are completely diff and the tq is just as close in numbers for peak.
its all in the cams and u can make the same power or very close to it and design it for rpm ranges u are looking to run..
also alot of the time a destroke engine will show a better avg number vs a stroker engine..but hey i guess i dont know jack **** about engines though..lol
the 355 shows around 995hp at 8786 rpms.
the 2 cams are completely diff and the tq is just as close in numbers for peak.
its all in the cams and u can make the same power or very close to it and design it for rpm ranges u are looking to run..
also alot of the time a destroke engine will show a better avg number vs a stroker engine..but hey i guess i dont know jack **** about engines though..lol
09-25-2007, 12:18 AM
#32
FormerVendor
Originally Posted by suicidal racing
destoke enignes means longer rods most the time and there is alot good done buy running longer rods..less force on the piston skirt and bore on the block.which cuts done in friction.
u tend to get better rod ratios also buy useing this and can run good comp height on pistons.
i am a big fan of destoked engines..the oh well u have to rev higher to make just as much hp as what u would make with a stroker engine is B.S.that is all in the cam and if u design a cam ment for a destroke application u can spin it to the same rpm as a stroker engine and make the same power at peak rpm if done right.
i've designed engine in the 447ci range that would spin higher then a 355 engine(4.155 bore and 3.27 stroke) and make about the same power.
also i like the fact that a destroked engine most of the time has a wider power band.
u tend to get better rod ratios also buy useing this and can run good comp height on pistons.
i am a big fan of destoked engines..the oh well u have to rev higher to make just as much hp as what u would make with a stroker engine is B.S.that is all in the cam and if u design a cam ment for a destroke application u can spin it to the same rpm as a stroker engine and make the same power at peak rpm if done right.
i've designed engine in the 447ci range that would spin higher then a 355 engine(4.155 bore and 3.27 stroke) and make about the same power.
also i like the fact that a destroked engine most of the time has a wider power band.
I cant even tell what you are saying? Also destroked engines have narrower powerbands not wider and need more gears to go the same distance in the same time. You cant look at powerband width in terms of rpm unless you also figure in the appropriate gearing. You have to run lower tighter gear spacing or you go slower with the "destroked" stuff 99 percent of the time.
09-25-2007, 12:26 AM
#33
FormerVendor
Originally Posted by suicidal racing
them engines where all out n/a engines the 447 from all the math and what it showed on paper was peaking around 9762 rpms and lil over 1008hp
the 355 shows around 995hp at 8786 rpms.
the 2 cams are completely diff and the tq is just as close in numbers for peak.
its all in the cams and u can make the same power or very close to it and design it for rpm ranges u are looking to run..
also alot of the time a destroke engine will show a better avg number vs a stroker engine..but hey i guess i dont know jack **** about engines though..lol
the 355 shows around 995hp at 8786 rpms.
the 2 cams are completely diff and the tq is just as close in numbers for peak.
its all in the cams and u can make the same power or very close to it and design it for rpm ranges u are looking to run..
also alot of the time a destroke engine will show a better avg number vs a stroker engine..but hey i guess i dont know jack **** about engines though..lol
Also I would look at calibrating those dynos you are using or quoting to say the least!
Right now whoever built these gems could be running Greg Anderson and company out of business!
995hp at 8800 at 355CID! That's the first 660 ft.lb. 355 CID engine I have ever seen!!!
You are making like 1.85 ft.lb. of TQ per inch! You just blew away F1, Pro-Stock and NASCAR all at once!!!
09-25-2007, 12:33 AM
#34
FormerVendor
BTW usually you will see around 10% loss of peak TQ by peak HP or so in general. Sometimes more and sometimes less but around that number in general. Just trying to keep it real.
Oldsstroker, you have just seen a new record in your quest for BMEP at peak power! Isn't the internet awsome! Anything can happen here just like in the Matrix.
Oldsstroker, you have just seen a new record in your quest for BMEP at peak power! Isn't the internet awsome! Anything can happen here just like in the Matrix.
09-25-2007, 03:44 AM
#35
nhra prostock engines make around 800-850 peak tq and avg around 1360hp.
as for the other comment..i had a outlaw 412ciu sb2.2 engine that made 881hp just shy under 8500rpms and 776lbs of tq at 7000 rpm and the engine was built for 2 stages of juice with 14-1 comp and a custom cam..them numbers are what it did on the dyno and was done over 4 years ago now.i sold it right after i built it because of family reasons and it went to tenn in a grudge car.
as for the power band **** and the rpm again start learning cams and the black magic of designing them..
other then that i'm done with this thread
as for the other comment..i had a outlaw 412ciu sb2.2 engine that made 881hp just shy under 8500rpms and 776lbs of tq at 7000 rpm and the engine was built for 2 stages of juice with 14-1 comp and a custom cam..them numbers are what it did on the dyno and was done over 4 years ago now.i sold it right after i built it because of family reasons and it went to tenn in a grudge car.
as for the power band **** and the rpm again start learning cams and the black magic of designing them..
other then that i'm done with this thread
09-25-2007, 05:46 AM
#36
FormerVendor
Originally Posted by suicidal racing
nhra prostock engines make around 800-850 peak tq and avg around 1360hp.
as for the other comment..i had a outlaw 412ciu sb2.2 engine that made 881hp just shy under 8500rpms and 776lbs of tq at 7000 rpm and the engine was built for 2 stages of juice with 14-1 comp and a custom cam..them numbers are what it did on the dyno and was done over 4 years ago now.i sold it right after i built it because of family reasons and it went to tenn in a grudge car.
as for the power band **** and the rpm again start learning cams and the black magic of designing them..
other then that i'm done with this thread
as for the other comment..i had a outlaw 412ciu sb2.2 engine that made 881hp just shy under 8500rpms and 776lbs of tq at 7000 rpm and the engine was built for 2 stages of juice with 14-1 comp and a custom cam..them numbers are what it did on the dyno and was done over 4 years ago now.i sold it right after i built it because of family reasons and it went to tenn in a grudge car.
as for the power band **** and the rpm again start learning cams and the black magic of designing them..
other then that i'm done with this thread
Why don't you post up one of those dyno sheets with 776 TQ from a 412 inch small block as I would love to see that! How did the engine drop 230 ft.lbs. of TQ by peak power at 8500???
While you're at it the 447 peaking at 9800 rpm would be a nice dyno sheet to see too.
Not trying to make you mad at all but rather just keepin it real as they say.
Damn! I have to go to sleep!
09-25-2007, 01:21 PM
#38
Suicidal,
From reading your post's I have learned one thing. You can't spell worth a ****.
Oh and the 447 that you did on paper doesn't have **** on my 327 that I did on paper. That bitch turned 1023 hp at only 6000 rpms. I guess you are the one that don't know **** about cam design.....
From reading your post's I have learned one thing. You can't spell worth a ****.
Oh and the 447 that you did on paper doesn't have **** on my 327 that I did on paper. That bitch turned 1023 hp at only 6000 rpms. I guess you are the one that don't know **** about cam design.....
