Re: Safety of 7 cyl wide open throttle, several times ?
[Re: Mr.Yuck]
#458988
09/04/09 12:22 PM
09/04/09 12:22 PM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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my guess is he wants to run the motor baseline w/all 8 cyls on a dyno, and then run it 8 times, each time with a different cyl disconnected to find out how much each cyl contributes to the overall power production, and to see if some make more power than others due to different factors, mainly intake and exhaust runner length variation would be my guess.
don't know the answer to your questions, though.
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Safety of 7 cyl wide open throttle, several times ?
[Re: patrick]
#458989
09/04/09 02:58 PM
09/04/09 02:58 PM
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Joined: Oct 2003
Posts: 21,345 Marysville, O-H-I-O
70Cuda383
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Marysville, O-H-I-O
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I think you might be ok.
don't know about the heat differences in the chambers possibly causing stresses on the head, or hurting the head gasket, but as far as only seeing impusles from 7 cylinders instead of 8...it shouldn't hurt anything...only 1 cylinder fires at a time anyway,
**Photobucket sucks**
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Re: Safety of 7 cyl wide open throttle, several times ?
[Re: Mr.Yuck]
#458990
09/04/09 03:01 PM
09/04/09 03:01 PM
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Joined: Jan 2003
Posts: 75,043 U.S.S.A.
JohnRR
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Quote:
What? are you that bored? I can tell you on a 440 one burned plug wire is worth about 4 tenths and a bunch of MPH. Not even sure if it was burned up at the start or not.
switch a holley on to it to pick up the 4 tenths ?
otherwise he MUST be an engineer ??
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Re: Safety of 7 cyl wide open throttle, several times ?
[Re: JohnRR]
#458991
09/04/09 04:06 PM
09/04/09 04:06 PM
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Joined: Jun 2004
Posts: 3,384 St. Charles, MO
wingman
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Or you could just run it and divide by 8. Some folks have a lot of time on their hands!
1969 Dodge Coronet Super Bee 383 A4 1970 Plymouth Road Runner 440 FC7 (sold)
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Re: Safety of 7 cyl wide open throttle, several times ?
[Re: wingman]
#458992
09/04/09 04:38 PM
09/04/09 04:38 PM
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Joined: Sep 2005
Posts: 12,481 Chino Valley
RodStRace
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Why do the full throttle? I'm sure as heck aren't going to tell someone that asks such a question it's okay. You will blame me for any issues now and for as long as you own the car.....
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Re: Safety of 7 cyl wide open throttle, several times ?
[Re: RodStRace]
#458996
09/07/09 09:06 AM
09/07/09 09:06 AM
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Joined: Jan 2006
Posts: 8,162 USA
360view
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OP
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maybe I got this Bass-Akwards and should instead be cutting out 7 cylinders with Noid lights, and running only one cylinder at a time? quote from retired Chrysler engineer Bob Scott: ------- I worked for a year on the fuel injection program and during that time I was involved with the single cylinder testing I was telling you about. The single cylinder test stand was a 354 ci Chrysler hemi that had all but one piston, rod and valve set removed. The thinking at the time was it would be easier to work on one cylinder, make changes and get answers before making parts to test on a complete engine. The single cylinder engine had a means of advancing and retarding the camshaft while the engine was running and we could remove the cam lobes individually (exhaust and intake) and try different combinations and indexing on an almost infinite basis. The intake was one perfectly straight tube that slid over another with close tolerance (like a trombone slide) so it could be lengthened and shortened to find the best possible length for the speed the engine was running. Intake runner tuning is the result of finding the point where the sonic resonance is maximized. When you put your hand in front of your bass stereo speaker you notice there is an air push. The same thing occurs in an engine. You can hear the induction resonance when you step on the gas with the air cleaner removed. This intake resonance is very pronounced on a single cylinder engine, particularly when recorded and played back at a slower speed, which we used to do. It sounds like Bop, Bop, Bop. By the way, we also took high-speed films of the valve train and watched them in slower motion. All sorts of weird things that would never have been normally visible were discovered and fixed in this manner. Someone, I think a brilliant engineer by the name of Bob Graham, deduced that if we tuned our intake runner to the point where the resonance was greatest, it would give the maximum push to the air and fuel when the intake valve opened at any given speed. The theory proved correct in the tests on the single cylinder and the results were reduced to a formula that was used from that day forward for ram manifolds on Chrysler engines. The runner as measured from the valve seat to the plenum (the open area where they normally meet under the carburetor,) can be determined by dividing 84,000 by the length of the runner = the speed the runner will work the best. An example is: 84000 (constant) = 5250 rpm -------------- 16 (runner length) The formula worked with all camshaft designs tested, engine displacements, compression ratios, and bore and stroke combinations of the time. An exhaust tuning formula was also developed on the single cylinder test stand. An example is: 205000 (constant) = 5256 rpm 39 (length of exhaust runner to collector) On the exhaust tuning we found that we could flatten out the torque curve by adding length to the collector (the point where all the runners meet.) The collector on an engine with all cylinders operating was usually a tube measuring about 20% smaller than the total of all the exhaust runners. ------ end quote from http://www.allpar.com/history/memories/bob-scott.html
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Re: Safety of 7 cyl wide open throttle, several times ?
[Re: 360view]
#458997
09/07/09 09:16 AM
09/07/09 09:16 AM
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Joined: Jan 2003
Posts: 75,043 U.S.S.A.
JohnRR
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Quote:
Is it wrong to think of a V8 as eight individual engines worthy of being checked one by one?
in a PERFECT world yes , in a V8 engine , especially if it's as built from the factory , NOT a chance .
I'm doing a build right now , have done a ton of cyl. head machining, have close to 50 hrs invested , of the open chambers for a quench dome piston. I cc'd every chamber, twice to myself, and found that no 2 chambers were the same CC and one head is bigger than the other by a cc or so. Unless one were to spend untold hours making every cylinder identical in every way , equal length intake runners and exh piping , and multiport fuel injection I doubt that each cylinder would produce the EXACT SAME hp figure.
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