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Just for fun, I want to play with some numbers here, because this seems like the right place to do it.
Theoretical 373ci (3.9" x 3.9") square stroker motor as the base. MMS205 heads, for this example.
The heads flow 300cfm, which will take the 3.9" bore and stroke out to 7,200rpms according to the Wallace Racing Calculators.
According to the same calculators, the MCSA has to be 2.47in^2 in order to reach 7,200rpms with the 3.9" bore and stroke.
I don't have the actual measurements of the MMS205 ports, but I found somewhere mentioning the AFR205's having a ~2.5 CSA at/near the port opening. If this number is at all accurate, it would appear to be adequate EXCEPT that the calculations are based on MCSA, not average CSA.
And conventional wisdom suggests that the MCSA is ~85-90% of the intake valve. The MMS205 has a 1.975" intake valve, which equates to a 1.69-1.78in^2 MCSA. On the 3.9" bore and stroke, a 1.78in^2 MCSA chokes out at 5,200rpms.
But to achieve the 2.47in^2 MCSA to get to 7,200rpms, I would need a 2.72" intake valve, following the same logic... which is obviously ludacris and not at all possible.
A co worker of mine just went 7.15 in the 1/8 mile. 416ci stroker
86 Monte carlo SS
Victor Jr with carb
4L80E with stall
TFS LS3 255 heads
Custom cam
Its s gull interior G body
Car will be faster once the suspension is dialed in
Our '80 malibu wagon with FED Stage 1 ls3 heads on an LS3 based 415 ran 10.06 at 132 in 4100 ft DA this last weekend. We'll be in the 9's with it soon as the weather cools off again, but aren't chassis certed so it'll be a one and done kind of thing. Going 6.3x at ~107-108 in the 1/8th.
Only made 645 horsepower on the engine dyno how we run it on track. Bitch hauls the mail.
Oh, and shift at 7000 and go through the lights at ~7300 rpm. Don’t need to spin the **** out of it. Needs a bigger intake to turn 7500+ the victor jr is tapped out.
i'll throw my .02 in...My decision was around not doing something twice or wishing i did it differently so i saved until i could pull the strings. I went with Brodix BR7's from WCCH..because i knew others had success with a LSX 454.
Bullet cam 246/258 .639" 113
Mast Intake (very challenging to fit but got it)
pump gas 91 octane 28 degrees at WOT
11.5:1 CR
744hp @ 6900rpm / 644Tq max at the flywheel
only issue on the test stand - we only had 1-3/4" headers so i left some on the table.
very streetable and never looked back - does cause a traction issue on the track.
spend the money on the heads and do your homework
That is why I focus on heads so much. I would rather be able to slightly undercam and have the heads carry than have to overcam to compensate for the heads. Imo you have a mild cam for a 454 and it looks like it runs great.
Just for fun, I want to play with some numbers here, because this seems like the right place to do it.
Theoretical 373ci (3.9" x 3.9") square stroker motor as the base. MMS205 heads, for this example.
The heads flow 300cfm, which will take the 3.9" bore and stroke out to 7,200rpms according to the Wallace Racing Calculators.
According to the same calculators, the MCSA has to be 2.47in^2 in order to reach 7,200rpms with the 3.9" bore and stroke.
I don't have the actual measurements of the MMS205 ports, but I found somewhere mentioning the AFR205's having a ~2.5 CSA at/near the port opening. If this number is at all accurate, it would appear to be adequate EXCEPT that the calculations are based on MCSA, not average CSA.
And conventional wisdom suggests that the MCSA is ~85-90% of the intake valve. The MMS205 has a 1.975" intake valve, which equates to a 1.69-1.78in^2 MCSA. On the 3.9" bore and stroke, a 1.78in^2 MCSA chokes out at 5,200rpms.
But to achieve the 2.47in^2 MCSA to get to 7,200rpms, I would need a 2.72" intake valve, following the same logic... which is obviously ludacris and not at all possible.
Am I doing this correctly?
Nope - simple mistake. You took 85% of the intake valve, but didn't solve for the area.
I remember when we built my last street car, 700rwhp ford lightning. I heard all the same stuff. In the end, it still wasnt fast enough. Barely was even scary anymore after a summer of beating on it. lol. Ran low 10s in full street trim, heat, ac, stereo, etc. Meh, wasnt scared for my life like i was led to believe. Fun as hell rolling burnouts everywhere tho.
I was talked outta the gt500 4v swap i really wanted to do in my lightning. Because this build was gunna be so nasty on the street, " i was gunna poop my lil pants!" Lol, what a joke that was.
Some of that could have been vehicle weight. I got a 10.1 shakedown and got tossed but the car weighs 3460 with me in it and fuel. I use a full gas tank for ballast. Friend of mine had to put an anvil in his trunk to get traction on a 3200 of TA making similar power.
When I first put my current motor together it did scare the **** out of me. Now i got used to it so it is less scary. I want to take some more rotational weight out to restore that fear factor.
Just for fun, I want to play with some numbers here, because this seems like the right place to do it.
Theoretical 373ci (3.9" x 3.9") square stroker motor as the base. MMS205 heads, for this example.
The heads flow 300cfm, which will take the 3.9" bore and stroke out to 7,200rpms according to the Wallace Racing Calculators.
According to the same calculators, the MCSA has to be 2.47in^2 in order to reach 7,200rpms with the 3.9" bore and stroke.
I don't have the actual measurements of the MMS205 ports, but I found somewhere mentioning the AFR205's having a ~2.5 CSA at/near the port opening. If this number is at all accurate, it would appear to be adequate EXCEPT that the calculations are based on MCSA, not average CSA.
And conventional wisdom suggests that the MCSA is ~85-90% of the intake valve. The MMS205 has a 1.975" intake valve, which equates to a 1.69-1.78in^2 MCSA. On the 3.9" bore and stroke, a 1.78in^2 MCSA chokes out at 5,200rpms.
But to achieve the 2.47in^2 MCSA to get to 7,200rpms, I would need a 2.72" intake valve, following the same logic... which is obviously ludacris and not at all possible.
Am I doing this correctly?
MCSA diameter is usually 90% of the valve diameter, so you would be looking at about 2.49sq inches for a 1.975” valve.
LSX67RS...nice set up, id be thrilled with that kinda power. Thats an iron block 454 you went with? More details about your ride please
Thx for the comments... 454 iron block...set it up for track events DSE suspension/Dailey Dry Sump. tracked it while it was primer so i can work the bugs out. Getting paint this year...
Awesome. Thank you, Spanks & KCS! I will have to remember that.
Wallace Racing Calculators puts the port velocity of this theoretical combination (2.47in^2 @ 7,200rpms with 3.9" bore and stroke) at ~610fps... that seems really high.
Awesome. Thank you, Spanks & KCS! I will have to remember that.
Wallace Racing Calculators puts the port velocity of this theoretical combination (2.47in^2 @ 7,200rpms with 3.9" bore and stroke) at ~610fps... that seems really high.
Is there such a thing as too much port velocity?
Very much so. Mach 1 is the practical limit of flow through an orifice for compressible flow. Flow is choked when you reach mach, and nasty things can start to happen that actually disrupt flow.
There are research papers that show "mean inlet mach" speed to be optimally ~50%. 50-60% is a period of choking, and above 60% is significant falloff. .5-.6 MIM speed is a good target for a very high performance engine.
With a 60% average MIM, it is very likely that the airspeed around the valve is extremely close if not at Mach 1.
Awesome. Thank you, Spanks & KCS! I will have to remember that.
Wallace Racing Calculators puts the port velocity of this theoretical combination (2.47in^2 @ 7,200rpms with 3.9" bore and stroke) at ~610fps... that seems really high.
Is there such a thing as too much port velocity?
Absolutely. General concensus is that .55mach is the max average airspeed a port can maintain before losing power, and only the best port designs can do that. A shitty Ford 302 windsor head for example would die well before that. Thats because the localized velocities in the port, like over the short turn or in the corner radii, will spike and disrupt the airflow at low average velocties.
Our '80 malibu wagon with FED Stage 1 ls3 heads on an LS3 based 415 ran 10.06 at 132 in 4100 ft DA this last weekend. We'll be in the 9's with it soon as the weather cools off again, but aren't chassis certed so it'll be a one and done kind of thing. Going 6.3x at ~107-108 in the 1/8th.
Only made 645 horsepower on the engine dyno how we run it on track. Bitch hauls the mail.
Oh, and shift at 7000 and go through the lights at ~7300 rpm. Don’t need to spin the **** out of it. Needs a bigger intake to turn 7500+ the victor jr is tapped out.
Badass!! Just as i said earlier.... the factory LS3 heads are just as good as the aftermarket LS3 heads. What intake? Hydraulic roller? Raceweight? And is it on pump gas ?
The car is ~3200 w/ driver. It is a powerglide and has 4.56 gears.
Engine made best power at 29* on 91 octane. Actually turned out a bit more mild than we expected. To make it more racey it needs ~8-10 degrees more duration on each, but the victor jr is restricting the top end. Someday I'll do a hi-ram and fuel injection and turn the thing 7800 and it'll fly, but again...can't best 10.0 or 135mph without tearing the car up so it is pretty much in the sweet spot now.
It made 644 with a throttle stop under the carb (used for 10.90 index racing). With a 2" plenum spacer in it's place it made 20hp and an extra 12 ft lb everywhere in the powerband. A switch from a Holley 750 to an 850 only showed 1-2 horsepower more. Best number was 663hp, and how it is in the car made 644. Has a fantastic powerband that's very broad and really accelerates the car through the middle of the track.
4.065 x 4" FED stage 1 LS3 11.4:1 on 91 octane Comp 243/257 110+2 hydraulic w/ cermaic CTS-VR lifters, .638/.638 EHI/EHX lobes Victor jr port matched to the heads w/ Holley 750 Mahle forged pistons, 1/1/2mm rings (these are a lot higher tension than you'd think...) Vacuum pump Manley 4" crank and 6.125 rods.
i'll throw my .02 in...My decision was around not doing something twice or wishing i did it differently so i saved until i could pull the strings. I went with Brodix BR7's from WCCH..because i knew others had success with a LSX 454.
Bullet cam 246/258 .639" 113
Mast Intake (very challenging to fit but got it)
pump gas 91 octane 28 degrees at WOT
11.5:1 CR
744hp @ 6900rpm / 644Tq max at the flywheel
only issue on the test stand - we only had 1-3/4" headers so i left some on the table.
very streetable and never looked back - does cause a traction issue on the track.
spend the money on the heads and do your homework
Yep, excellent results
My BR7's are the BS 275 versions with Crower shaft rockers....done up by Richard at WCCH, and my static is 13:1 for our pump E54 here in AZ.
I've got some cubic inches on your setup, and a larger cam too...I have ARH 2" on my car with 3" titanium Akrapovic exhaust.
Hoping to have it all back together and ready for some track time in the fall......maybe in time for November and the Mondo layout, if they can still run that config.
We have some private rentals out at Indi too
Yep, excellent results
My BR7's are the BS 275 versions with Crower shaft rockers....done up by Richard at WCCH, and my static is 13:1 for our pump E54 here in AZ.
I've got some cubic inches on your setup, and a larger cam too...I have ARH 2" on my car with 3" titanium Akrapovic exhaust.
Hoping to have it all back together and ready for some track time in the fall......maybe in time for November and the Mondo layout, if they can still run that config.
We have some private rentals out at Indi too
Which puts my original guess of 760hp at the flywheel for your build not far off...damn these pushrod motors are impressive!
The car is ~3200 w/ driver. It is a powerglide and has 4.56 gears.
Engine made best power at 29* on 91 octane. Actually turned out a bit more mild than we expected. To make it more racey it needs ~8-10 degrees more duration on each, but the victor jr is restricting the top end. Someday I'll do a hi-ram and fuel injection and turn the thing 7800 and it'll fly, but again...can't best 10.0 or 135mph without tearing the car up so it is pretty much in the sweet spot now.
It made 644 with a throttle stop under the carb (used for 10.90 index racing). With a 2" plenum spacer in it's place it made 20hp and an extra 12 ft lb everywhere in the powerband. A switch from a Holley 750 to an 850 only showed 1-2 horsepower more. Best number was 663hp, and how it is in the car made 644. Has a fantastic powerband that's very broad and really accelerates the car through the middle of the track.
4.065 x 4" FED stage 1 LS3 11.4:1 on 91 octane Comp 243/257 110+2 hydraulic w/ cermaic CTS-VR lifters, .638/.638 EHI/EHX lobes Victor jr port matched to the heads w/ Holley 750 Mahle forged pistons, 1/1/2mm rings (these are a lot higher tension than you'd think...) Vacuum pump Manley 4" crank and 6.125 rods.
Im impressed!! Thats 1.59 hp per cube on pump gas. Thats right where a strong street motor on pump gas suppose to be. Those vacuum pumps are worth 20 horses alone im thinking.
Which puts my original guess of 760hp at the flywheel for your build not far off...damn these pushrod motors are impressive!
Can't wait
Hint.......a similar setup with less cam and compression with a 1 3/4 header !!!!! ....still testing.
Intake manifold kept it from peaking higher, along with those small headers, as it couldn't breathe past 6400 RPM ;-)
Im impressed!! Thats 1.59 hp per cube on pump gas. Thats right where a strong street motor on pump gas suppose to be. Those vacuum pumps are worth 20 horses alone im thinking.
Thanks!
The vacuum pump was worth only like 8 horsepower from what I remember. We broke it in without the vacuum pump hooked up, and then it picked up a little through the entire powerband pulling 12-14 inches on the crank case.
The 1/1/2mm ring pack is fairly high tension still. More gains could've been had with a lower tension ringpack which requires vacuum against it to seal properly.
The vacuum pump was worth only like 8 horsepower from what I remember. We broke it in without the vacuum pump hooked up, and then it picked up a little through the entire powerband pulling 12-14 inches on the crank case.
The 1/1/2mm ring pack is fairly high tension still. More gains could've been had with a lower tension ringpack which requires vacuum against it to seal properly.
06-12-2019, 10:07 AM
