frictional losses of 4.25 stroke motor vs 4.0 stroke
08-22-2016 | 09:49 PM
#1
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From: frankenmuth michigan
frictional losses of 4.25 stroke motor vs 4.0 stroke
Bought performance trends 3.4 software to do my own theoretical builds of motors. Plugged in 548 at 8.4 compression vs 9.5 502 and my afr heads/good efi intake, current cam thats in my 548 which is in the 250/260 duration w .380 lobe lift, calculated theoretical torque/hp, was really surprised by the calculated frictional losses at 6500 rpms from higher piston speed from extra stroke. Basically the 540 made 45 or so more ft lbs of tq and around 40 more hp at 4500, about 35 to 40 more ft lbs tq and hp at 5000 , matched around 5500 to 6000 in the 680tq/690 to 700/710 hp range then went backwards at 6500 by 30 to 40 hp, even raising the theoretical compression to same still comes up short at 6500 w frictional lose of 4.25 stroke at 319hp vs about 275, really surprised. Ive heard the argument of guys saying a 4.0 stroke motor kicking a 4.25 stroke motors ass on top but never really believed it, any thoughts? If i use the 548 short block i slready own and my spare merlin block and old blower pistons i can have two 548s that make 45 to 5o more hp in the 4500/5000 range, same power as my 502s in the 5500 range than go backwards anything 6000 and up, surprised, thoughts, interjections?
Last edited by articfriends; 08-22-2016 at 09:52 PM.
08-22-2016 | 10:38 PM
#2
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From: On A Dirt Floor
Yes, my thoughts are who cares what a computer program or dyno guesses at frictional power.
Reason for going toless stroke would be if you are going to exceed the piston's critical speed / acceleration or obviouslyh too much rod angle or pulling pistons out of bottom of bore.
The net engine power went down at higher rpms with the bigger cube because of using the same intake, heads, cam and etc with the two motors.
Let's give the larger cids different parts and we'll smoke that 502in that 6000rpm + range too.
Reason for going toless stroke would be if you are going to exceed the piston's critical speed / acceleration or obviouslyh too much rod angle or pulling pistons out of bottom of bore.
The net engine power went down at higher rpms with the bigger cube because of using the same intake, heads, cam and etc with the two motors.
Let's give the larger cids different parts and we'll smoke that 502in that 6000rpm + range too.
08-22-2016 | 10:55 PM
#3
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From: frankenmuth michigan
Im going to play w numbers more in next week or so, the cam in 548 is already on edge for how little compression it has, i would prob use a smaller cam in a 502 since this thing idled weak already in its last go around when running na. Im gearing up for extensive dyno testing of my 548 soon, going to put a ideal efi intake w big throttle body on using mefi3 harness and mefi burn to tune it, try to find every last possible hp (nice thing about having my own personal dyno) THEN bolt on a 500 efi intake and test, mod, test, mod, test until i start to loose more tq than hp gained to see how far i can go,made 650 something w this 540 in past w mpi intake , im wanting to see how clpse to a "good efi intake i can make a 500 intake go
Last edited by articfriends; 08-22-2016 at 11:00 PM.
08-23-2016 | 05:57 AM
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From: On A Dirt Floor
Here is intake manifold sizing specs from Pipemax when I ran the program years ago for a 540cid for someone looking to make max power from 5600-5800rpm in a boat.
Originally Posted by SB
To measure port length, measure top of port(Roof) and measure bottom(Floor) of port. Add together. Then divide by 2.
Pipemax:
{use Scotch 3M 218 Fine Line Tape to measure Roof and Floor Lengths}
- Induction System Tuned Lengths - ( Cylinder Head Port + Manifold Runner )
1st Harmonic= 36.977" (usually this Length is never used)
2nd Harmonic= 20.987" (some Sprint Engines and Factory OEM's w/Injectors)
3rd Harmonic= 14.652" (ProStock or Comp SheetMetal Intake)
4th Harmonic= 11.532" (Single-plane Intakes , less Torque)
5th Harmonic= 9.357" (Torque is reduced, even though Tuned Length)
6th Harmonic= 7.872" (Torque is reduced, even though Tuned Length)
7th Harmonic= 6.794" (Torque is greatly reduced, even though Tuned Length)
8th Harmonic= 5.975" (Torque is greatly reduced, even though Tuned Length)
Note> 2nd and 3rd Harmonics typically create the most Peak Torque
4th Harmonic is used to package Induction System underneath Hood
Plenum Runner Minimum Recommended Entry Area = 3.194 to 3.593 Sq.Inch
Plenum Runner Average Recommended Entry Area = 3.672 Sq.Inch
Plenum Runner Maximum Recommended Entry Area = 3.751 to 4.439 Sq.Inch
Minimum Plenum Volume CC = 1157.9 [typically for Single-Plane Intakes]
Minimum Plenum Volume CID= 70.7 [typically for Single-Plane Intakes]
Maximum Plenum Volume CC = 8861.2 [typically for Tunnel Ram Intakes]
Maximum Plenum Volume CID= 540.7 [typically for Tunnel Ram Intakes]
================================================== ====
-- Cross-Sectional Areas at various Intake Port Velocities (@ 28 in.) ---
159 FPS at Intake Valve Curtain Area= 4.524 sq.in. at .640 Lift
181 FPS at Intake Valve OD Area and at Convergence Lift = .563
223 FPS 90% PerCent Rule Seat-Throat Velocity CSA= 3.221 sq.in. at 5600 RPM
350 FPS Velocity CSA= 2.051 sq.in. at 5600 RPM Port Sonic-Choke with HP Loss
330 FPS Velocity CSA= 2.178 sq.in. at 5600 RPM Port Sonic-Choke with HP Loss
311 FPS Velocity CSA= 2.311 sq.in. at 5600 RPM Smallest Useable Port CSA
300 FPS Velocity CSA= 2.395 sq.in. at 5600 RPM Recommended Smallest Port CSA
285 FPS Velocity CSA= 2.521 sq.in. at 5600 RPM Recommended Smallest Port CSA
260 FPS Velocity CSA= 2.764 sq.in. at 5600 RPM Recommended Port CSA
250 FPS Velocity CSA= 2.874 sq.in. at 5600 RPM Recommended Port CSA
240 FPS Velocity CSA= 2.994 sq.in. at 5600 RPM Largest Intake Port Entry CSA
220 FPS Velocity CSA= 3.266 sq.in. at 5600 RPM Largest Intake Port Entry CSA
210 FPS Velocity CSA= 3.422 sq.in. at 5600 RPM Torque Loss + Reversion
200 FPS Velocity CSA= 3.593 sq.in. at 5600 RPM Torque Loss + Reversion
Pipemax:
{use Scotch 3M 218 Fine Line Tape to measure Roof and Floor Lengths}
- Induction System Tuned Lengths - ( Cylinder Head Port + Manifold Runner )
1st Harmonic= 36.977" (usually this Length is never used)
2nd Harmonic= 20.987" (some Sprint Engines and Factory OEM's w/Injectors)
3rd Harmonic= 14.652" (ProStock or Comp SheetMetal Intake)
4th Harmonic= 11.532" (Single-plane Intakes , less Torque)
5th Harmonic= 9.357" (Torque is reduced, even though Tuned Length)
6th Harmonic= 7.872" (Torque is reduced, even though Tuned Length)
7th Harmonic= 6.794" (Torque is greatly reduced, even though Tuned Length)
8th Harmonic= 5.975" (Torque is greatly reduced, even though Tuned Length)
Note> 2nd and 3rd Harmonics typically create the most Peak Torque
4th Harmonic is used to package Induction System underneath Hood
Plenum Runner Minimum Recommended Entry Area = 3.194 to 3.593 Sq.Inch
Plenum Runner Average Recommended Entry Area = 3.672 Sq.Inch
Plenum Runner Maximum Recommended Entry Area = 3.751 to 4.439 Sq.Inch
Minimum Plenum Volume CC = 1157.9 [typically for Single-Plane Intakes]
Minimum Plenum Volume CID= 70.7 [typically for Single-Plane Intakes]
Maximum Plenum Volume CC = 8861.2 [typically for Tunnel Ram Intakes]
Maximum Plenum Volume CID= 540.7 [typically for Tunnel Ram Intakes]
================================================== ====
-- Cross-Sectional Areas at various Intake Port Velocities (@ 28 in.) ---
159 FPS at Intake Valve Curtain Area= 4.524 sq.in. at .640 Lift
181 FPS at Intake Valve OD Area and at Convergence Lift = .563
223 FPS 90% PerCent Rule Seat-Throat Velocity CSA= 3.221 sq.in. at 5600 RPM
350 FPS Velocity CSA= 2.051 sq.in. at 5600 RPM Port Sonic-Choke with HP Loss
330 FPS Velocity CSA= 2.178 sq.in. at 5600 RPM Port Sonic-Choke with HP Loss
311 FPS Velocity CSA= 2.311 sq.in. at 5600 RPM Smallest Useable Port CSA
300 FPS Velocity CSA= 2.395 sq.in. at 5600 RPM Recommended Smallest Port CSA
285 FPS Velocity CSA= 2.521 sq.in. at 5600 RPM Recommended Smallest Port CSA
260 FPS Velocity CSA= 2.764 sq.in. at 5600 RPM Recommended Port CSA
250 FPS Velocity CSA= 2.874 sq.in. at 5600 RPM Recommended Port CSA
240 FPS Velocity CSA= 2.994 sq.in. at 5600 RPM Largest Intake Port Entry CSA
220 FPS Velocity CSA= 3.266 sq.in. at 5600 RPM Largest Intake Port Entry CSA
210 FPS Velocity CSA= 3.422 sq.in. at 5600 RPM Torque Loss + Reversion
200 FPS Velocity CSA= 3.593 sq.in. at 5600 RPM Torque Loss + Reversion
Last edited by SB; 08-23-2016 at 06:02 AM.
08-23-2016 | 06:13 AM
#5
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From: frankenmuth michigan
So at 15.5 runner length do we try to get that to 14.5" or do we keep cutting divider to try to shift peak hp up and make intake act like its got more plenum area since its only about 1/3 of your minimum?
08-23-2016 | 07:13 AM
#8
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From: On A Dirt Floor
Per cid.
BAck in my racing days (few hundred years ago) I would always run into some import nit wit bench racer about how his motor makes more power per cid than mine.
A simple answer from me always was "then let's race to find out who's faster. How much you wanna run for ?" LOL.
Example in Chevy V8 sizes:
350cid 600hp = 1.71hp / cid
598 cid 1000hp = 1.67hp/cid
Who's boat or car wins ?
BAck in my racing days (few hundred years ago) I would always run into some import nit wit bench racer about how his motor makes more power per cid than mine.
A simple answer from me always was "then let's race to find out who's faster. How much you wanna run for ?" LOL.
Example in Chevy V8 sizes:
350cid 600hp = 1.71hp / cid
598 cid 1000hp = 1.67hp/cid
Who's boat or car wins ?
Last edited by SB; 08-23-2016 at 07:58 AM.
08-23-2016 | 08:00 AM
#9
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From: Fredericksburg, Va
Smitty, all comes from rod angle/side load on cylinder wall, yes may loose % there but they still over come it in the cu in from what I've seen, a couple of years ago several friends of mine all running 632's, kept breaking cranks, all from same deal but they had even more stroke, cylinder wall load..
