Re: 508” KB – B1 build
[Re: WadeMetzinger]
#2804929
08/04/20 10:23 AM
08/04/20 10:23 AM
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Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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The elevation at Checotah is only about 600’...... so if there is a high pressure system in the area, you can def see baro readings over 30”...... like right now.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 508” KB – B1 build
[Re: WadeMetzinger]
#2804960
08/04/20 11:17 AM
08/04/20 11:17 AM
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440Jim
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I asked him last night about those Man_P and Man_V and he said they weren't hooked up, so not sure what they are or what they were measuring..
It was raining on Friday so he did hook up the air plenum to a vent that pulls air from control room where he had a window A/C unit running. It wasn't very cool in there but the air was much dryer, he said pulling air from outside with the rain would be pointless as it would never run in the rain. Wade, Do you know if the air supply to the engine room has a fan forcing air into the room? Without one, the pressure in the room could drop as the exhaust pumps the room pressure down. "Man_P and Man_V not hooked up" Does that mean the sensor(s) were hanging in the engine room? i.e. just not installed on the engine If the engine room pressure was dropping due to duct restriction, that could explain lower power and the flatter torque. Assuming the dyno correction factor assumed the pressure constant (ambient/outside).
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Re: 508” KB – B1 build
[Re: Al_Alguire]
#2804962
08/04/20 11:21 AM
08/04/20 11:21 AM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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You’re right, what you want is the “observed” baro reading on site. But there won’t be much correction difference between 29.5 and 30.0. Certainly not enough to explain the massive CF on that sheet. The elevation correction for 600’ is .64 in/hg....... so if the corrected baro was 30.10”, the observed should be 29.46”.
I’d love to see an uncorrected sheet to see if for some reason there is an anomaly with the bsfc numbers.
The bsfc is supposed to be the result of fuel flow divided by the uncorrected HP. So, on the last line of the sheet the fuel flow is 356.4lbs/hr, and the result is .512. For the result to be .512, the uncorrected power would be 696hp. The corrected HP of 859.1 is just over 23.4% higher than 696.
If you look at Greg’s dyno sheet, which is in a town that’s about 300’ higher than where Wades motor was tested(and the sheet shows the baro as 29.13”), looking at the fuel flow and bsfc numbers you get an uncorrected power number of 830.8. The corrected number is 921.5, which works out to a 10.9% CF.
So, how is it that Wades motor, which was tested at a facility that sits at a 300’ lower elevation, and had a higher observed baro pressure...... ends up with what appears to be a nearly 13% higher CF?
What am I missing there?
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 508” KB – B1 build
[Re: 440Jim]
#2804966
08/04/20 11:26 AM
08/04/20 11:26 AM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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I asked him last night about those Man_P and Man_V and he said they weren't hooked up, so not sure what they are or what they were measuring..
It was raining on Friday so he did hook up the air plenum to a vent that pulls air from control room where he had a window A/C unit running. It wasn't very cool in there but the air was much dryer, he said pulling air from outside with the rain would be pointless as it would never run in the rain. Wade, Do you know if the air supply to the engine room has a fan forcing air into the room? Without one, the pressure in the room could drop as the exhaust pumps the room pressure down. "Man_P and Man_V not hooked up" Does that mean the sensor(s) were hanging in the engine room? i.e. just not installed on the engine If the engine room pressure was dropping due to duct restriction, that could explain lower power and the flatter torque. Assuming the dyno correction factor assumed the pressure constant (ambient/outside). Jim, the SF system is reading the baro pressure in real time. Though, where the sensor is on that particular SF system....... I’m not sure. But it would be reading the pressure of wherever it was.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 508” KB – B1 build
[Re: 440Jim]
#2804981
08/04/20 11:52 AM
08/04/20 11:52 AM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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In my experience, the weather reporting (typically from airports) publishes the barometric pressure corrected to sea level. This is so the aircraft can set their altimeter to show elevation above mean sea level (MSL); it would show 600 ft while on the ground at that airport. 600 ft MSL would correct the actual measurement of 29.46"Hg to 30.10"Hg [reported]
14.78 psi = 30.10"Hg (units conversion) not MSL correction 14.47 psi = 29.46"Hg
Dwayne, we may be putting 2 + 2 together. If the engine room pressure was dropping, the dyno correction factor would change noticeably if the SF system has a real time sensor near the engine/carb. I think something like that is going on. But having the room pressure change that much during a pull sure adds a lot of variables to the corrected result. There is a channel in the software for the baro reading, which can be displayed on one of the sheets if desired. We put it on the uncorrected data page here. It rarely changes much at all throughout a pull.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 508” KB – B1 build
[Re: 440Jim]
#2804989
08/04/20 12:31 PM
08/04/20 12:31 PM
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Joined: Feb 2004
Posts: 2,073 Tulsa, Ok
WadeMetzinger
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I asked him last night about those Man_P and Man_V and he said they weren't hooked up, so not sure what they are or what they were measuring..
It was raining on Friday so he did hook up the air plenum to a vent that pulls air from control room where he had a window A/C unit running. It wasn't very cool in there but the air was much dryer, he said pulling air from outside with the rain would be pointless as it would never run in the rain. Wade, Do you know if the air supply to the engine room has a fan forcing air into the room? Without one, the pressure in the room could drop as the exhaust pumps the room pressure down. "Man_P and Man_V not hooked up" Does that mean the sensor(s) were hanging in the engine room? i.e. just not installed on the engine If the engine room pressure was dropping due to duct restriction, that could explain lower power and the flatter torque. Assuming the dyno correction factor assumed the pressure constant (ambient/outside). You guys are talking way over my head...lol Here is a picture of the dyno room, there are 2 really high speed fans that he uses when making pulls, one pushes air in and one pulls air out. And then like I said below the plenum pull from a vent from the control room. (this picture is from a few years ago when I built that 572 B1 Drag Week motor with Monte Smith)
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Re: 508” KB – B1 build
[Re: fast68plymouth]
#2804991
08/04/20 12:36 PM
08/04/20 12:36 PM
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Joined: Jan 2003
Posts: 19,304 Las Vegas
Al_Alguire
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Well I can tell you my last visit to an unknown to me dyno was nothing less than a gong show from start to finish. In short we quit quite early as none of the numbers it was spitting out made any sense. So we just called it a day and loaded up and went home. IN retrospect maybe the HP number was closish to reality but nothing else made or makes any sense to this day. Specifically the BSFC numbers. I was ready to pull it after two small pulls based on what I saw. In the end in my case I believe it was more a function of a far out of date dyno that had its fair share of software issues. That engine has been 4.65 148.98 in Vegas in our 4 link dragster on a 112 degree evening a couple weeks back. DA was almost 6000' barometer was 27.74 so maybe it was close on HP but that was about it..Numbers correct to a way better engine than I though we had leaving the dyno. Still needs a converter as its way tight and some further tuning but it runs pretty well for a pretty mild deal. So I guess what I am saying is this would not be the first time I have seen numbers that make no sense on a dyno sheet. Its only a tool and only as good as the guy running it and the software supporting it. Wade will know once he gets it in the car what kind of power it truly makes for HP and Scales never lie Maybe we are just reading way to much into what's there, not without reason mind you but sometimes things just dont work as they should.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: 508” KB – B1 build
[Re: fast68plymouth]
#2804994
08/04/20 12:42 PM
08/04/20 12:42 PM
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Joined: Aug 2003
Posts: 43,007 Bend,OR USA
Cab_Burge
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The elevation at Checotah is only about 600’...... so if there is a high pressure system in the area, you can def see baro readings over 30”...... like right now. All barometer readings at any reporting airport are corrected to sea level readings, not the actual barometer reading, so all airplane altimeters are reading alike when landing at that airport. The FAA decided that long ago All airplane flying above 18,000 Ft are suppose to set their altimeter to 29.92 until they are ready to land and then descend below 18,000 Ft.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 508” KB – B1 build
[Re: Al_Alguire]
#2805001
08/04/20 12:58 PM
08/04/20 12:58 PM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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Al, what you’re describing is exactly why I say it’s never a good idea to compare numbers from different dynos.
Many times it’s not a fault of the dyno at all........ but a room that’s got some strange things going on.
If a motor I test goes into a car that’s really well set up(hooks, has the right gears, good converter, no fuel system woes, etc), and it’s being raced in “decent” air, the numbers will be very close to what the Moroso chart shows.
It happens that way sometimes, but it’s the exception rather than the rule.
What I use as a general rule to see if you’re even in the ball park is 90% of the corrected hp...... in “reasonable” air(not mineshaft air).
As an example....... 800STP power, 2800lb car, DA around 2500’, temps in the 70’s.......,the number on the Moroso chart should be 720hp(800 x .90) or better(800hp would be an 8.65@155....... while 720hp would be a 9.05@149.5) If you can’t get it to come that close(or better), there’s a good chance you might have some happy dyno numbers.
If you run at tracks high enough in elevation to use a correction factor....... then that has to be figured into the result as well.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 508” KB – B1 build
[Re: fast68plymouth]
#2805012
08/04/20 01:42 PM
08/04/20 01:42 PM
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Joined: Jan 2003
Posts: 19,304 Las Vegas
Al_Alguire
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Dwayen, trying figuring it out at altitude tracks like we have all over the west. Vegas is a solid .25 slower than say Sonoma, which is a solid .1-.15 slower than say Cecil, MIR or any number of east coast tracks I have run. When we first started coming to the midwest running the heads up car in the summer we expected to not run very well. But the barometer usually makes up for any shortcomings that the Humidity, Grains and VP might bring. We run generally better than we ever run out west. Partly due to the tracks but mostly the barometer back here. I have yet to run my car since coming to Ohio but the Wheatcratfs tell me to expect .1-.15 better Et in the summer here in the1/8 than "great" Vegas air. Guess what I am getting at is "decent" air on many of the east coast facilities I have been to is better than great air out west. Morale of the story is while the moroso calculator is yet another tool it cannot account for many variables that we all are keenly aware of. DA is not just DA alot goes into figuring that number and certain things, like barometer in particular play a very large role in how well a car will run. I can tell you that typical 4000' DA day in Vegas is going to be at least .3 slower than that same typical 4000'DA in say Norwalk. I have run in both. Just something to consider when we see posted ET slips and such.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: 508” KB – B1 build
[Re: 440Jim]
#2805016
08/04/20 02:07 PM
08/04/20 02:07 PM
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Joined: Aug 2011
Posts: 2,843 Pattison Texas
CSK
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I asked him last night about those Man_P and Man_V and he said they weren't hooked up, so not sure what they are or what they were measuring..
It was raining on Friday so he did hook up the air plenum to a vent that pulls air from control room where he had a window A/C unit running. It wasn't very cool in there but the air was much dryer, he said pulling air from outside with the rain would be pointless as it would never run in the rain. Wade, Do you know if the air supply to the engine room has a fan forcing air into the room? Without one, the pressure in the room could drop as the exhaust pumps the room pressure down. "Man_P and Man_V not hooked up" Does that mean the sensor(s) were hanging in the engine room? i.e. just not installed on the engine If the engine room pressure was dropping due to duct restriction, that could explain lower power and the flatter torque. Assuming the dyno correction factor assumed the pressure constant (ambient/outside). I think 440Jim nailed it, years ago we had a similar thing happen in a very small dyno room.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: 508” KB – B1 build
[Re: CSK]
#2805049
08/04/20 03:05 PM
08/04/20 03:05 PM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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Okay....... so let’s say there is an “air supply” problem in the dyno room, and the air pressure in the room is dropping as the run progresses, and as a result of that, the dyno software is adjusting the CF accordingly.
How does that situation change how the motor responds to the tuning changes?
The dropping air pressure would affect how effectively the motor takes in air, as well as how the carb meters fuel.
It’s hard for me to imagine an in car scenario where the engine would see the pressure at the carb drop significantly during a pass. If you had any kind of effective scoop....... the opposite should be happening.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 508” KB – B1 build
[Re: fast68plymouth]
#2809758
08/17/20 01:30 PM
08/17/20 01:30 PM
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Joined: Feb 2008
Posts: 711 Central TEXAS!!!!
sr4440
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I asked him last night about those Man_P and Man_V and he said they weren't hooked up, so not sure what they are or what they were measuring..
It was raining on Friday so he did hook up the air plenum to a vent that pulls air from control room where he had a window A/C unit running. It wasn't very cool in there but the air was much dryer, he said pulling air from outside with the rain would be pointless as it would never run in the rain. Wade, Do you know if the air supply to the engine room has a fan forcing air into the room? Without one, the pressure in the room could drop as the exhaust pumps the room pressure down. "Man_P and Man_V not hooked up" Does that mean the sensor(s) were hanging in the engine room? i.e. just not installed on the engine If the engine room pressure was dropping due to duct restriction, that could explain lower power and the flatter torque. Assuming the dyno correction factor assumed the pressure constant (ambient/outside). Jim, the SF system is reading the baro pressure in real time. Though, where the sensor is on that particular SF system....... I’m not sure. But it would be reading the pressure of wherever it was. the baro sensor is inside the control box. Joe
Without Data, you’re just another guy with an opinion.
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Re: 508” KB – B1 build
[Re: sr4440]
#2809776
08/17/20 02:17 PM
08/17/20 02:17 PM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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the baro sensor is inside the control box. Good to know...... thanks!! And that box is in the dyno cell, correct? On your 902, what are the ManP and ManV channels used for, and what would they be reading if you didn’t have the hoses attached to anything? Any thoughts on the widely variable CF on that run?
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 508” KB – B1 build
[Re: fast68plymouth]
#2809788
08/17/20 02:44 PM
08/17/20 02:44 PM
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Joined: Feb 2008
Posts: 711 Central TEXAS!!!!
sr4440
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the baro sensor is inside the control box. Good to know...... thanks!! And that box is in the dyno cell, correct? On your 902, what are the ManP and ManV channels used for, and what would they be reading if you didn’t have the hoses attached to anything? Any thoughts on the widely variable CF on that run? I didn't see it on the sheet he posted, but mine make small adjustments during the run (0.01) because of the temps in the room going up 1/2 degree. ok, seen your numbers, doesn't make sense because the baro sensor is in the control box right on top of the dyno. (FYI I also have a SF powermark) and he is getting outside air. I would really like to have a copy of the data file. edit the ManP and ManV is one pressure channel with a different way to look at the data -14.1 PSI is -28.70 inhg. 1 psi = 2.03602 inhg. But it shouldn't be moving around during a pull. It looks like pressure is building as the run goes on. Joe
Last edited by sr4440; 08/17/20 03:36 PM.
Without Data, you’re just another guy with an opinion.
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Re: 508” KB – B1 build
[Re: sr4440]
#2809790
08/17/20 02:48 PM
08/17/20 02:48 PM
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Joined: Feb 2008
Posts: 711 Central TEXAS!!!!
sr4440
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Wade A few comments just looking at your dyno sheet. 1st did he weight your fuel? Because the default is .750 and renegae 112 is .711 @60 degrees F. So my 1st thought is your BSFC should be better unless the fuel was 40 degrees then it may have had a .750 SG 2nd did he tell you why he was running the Inertia correction factor at a 1.000?
Wade, I would ask him to email you a “customer data pack”. That has ALL of the data taken in by the dyno. Plus it allows you to do some post run corrections.
For those of you that don’t know what STPIPw and STPiTr are. It is corrected to STP J-607 and with inertia correction. Inertia correction is a factor added (or taken away from a decell test) the torque reading. Why is inertia factor added? It has to do with Newtons 1st law of motion “an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force”. When we do a sweep test on a Dyno, we have to accelerate the crankshaft, flywheel, drive plate, driveshaft and dyno brake. All of this takes energy and that energy can’t be measured by the brake because it being stored in all the rotating mass. Each engine has a different factor.
How do you determine the engines “Inertia factor”. You run a special sweep up and down, doesn’t have to be at full throttle. Now if you correction factor is right the HP and Tq lines will lay over each other, because we are correcting (by adding) for the energy being stored during accell and correcting (by removing) during decell. If the number is not right it can be adjusted during post analysis until it is correct.
So what have we done? Well now we can make a sweep at 200 rpm per second and 600 rpm per second and get the same HP reading. You can do a step test and get the same reading. Before a 750 rpm per second read would always have a lower HP reading than a 400 rpm reading per second run.
Joe
Without Data, you’re just another guy with an opinion.
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Re: 508” KB – B1 build
[Re: sr4440]
#2809791
08/17/20 02:59 PM
08/17/20 02:59 PM
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Joined: Aug 2011
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CSK
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Wade A few comments just looking at your dyno sheet. 1st did he weight your fuel? Because the default is .750 and renegae 112 is .711 @60 degrees F. So my 1st thought is your BSFC should be better unless the fuel was 40 degrees then it may have had a .750 SG 2nd did he tell you why he was running the Inertia correction factor at a 1.000?
Wade, I would ask him to email you a “customer data pack”. That has ALL of the data taken in by the dyno. Plus it allows you to do some post run corrections.
For those of you that don’t know what STPIPw and STPiTr are. It is corrected to STP J-607 and with inertia correction. Inertia correction is a factor added (or taken away from a decell test) the torque reading. Why is inertia factor added? It has to do with Newtons 1st law of motion “an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force”. When we do a sweep test on a Dyno, we have to accelerate the crankshaft, flywheel, drive plate, driveshaft and dyno brake. All of this takes energy and that energy can’t be measured by the brake because it being stored in all the rotating mass. Each engine has a different factor.
How do you determine the engines “Inertia factor”. You run a special sweep up and down, doesn’t have to be at full throttle. Now if you correction factor is right the HP and Tq lines will lay over each other, because we are correcting (by adding) for the energy being stored during accell and correcting (by removing) during decell. If the number is not right it can be adjusted during post analysis until it is correct.
So what have we done? Well now we can make a sweep at 200 rpm per second and 600 rpm per second and get the same HP reading. You can do a step test and get the same reading. Before a 750 rpm per second read would always have a lower HP reading than a 400 rpm reading per second run.
Joe Great info, Thank you Joe
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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