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OK everybody, heres your chance to get out your clubs and beat me like a baby seal. Awhile back there was a thread on the validity of dynos. At that time I posted these dyno sheets. On the 6000 rpm pull there was a spark plug wire off on the #2 cyl.(see RGT sheet). After hooking upthe wire, the motor picked up 138 HP at 6000 rpm. But it turns out that the #2 cyl was very sick cylinder. Notice the torque drop between 5300 and 5800 on the 6400 pull sheet. Notice also that the fuel flow drops off as well. This tells me that the air flow thru the carbs fell off also. This is a considerable drop and should not be taken lightly. What was the cause? Well I was convinced that it was intake valve bounce but didn't know why. Isky 9945 Super RAD Tool Room Springs, heavy wall Manton pushrods, and a very low intensity cam profile. I was told by more than a couple of people that it would get worse before it got better, specially as the Rs went up. Well, it did. After towing a 1000 mi to Burley Idaho, the thing raised it ugly ass head, right off the trailer. The damn thing unraveled big time. Snapped a link bar on a set of rollers, bent to hell intake pushrod, including having both ends knocked right out of it, scubbed cam lobes, and for some unknown reason, ripped the exhaust rocker right out of its stand. Turns out the #2 cyl was the sole cause of the torque drop, even though it added 138 hp at the same rpm once it was added to the game. What was the cause of all this maylay you wonder? Well here is a chance for all the gurus to figure it out. I will tell you this... the same thing can happen to a BBC oil filter, a fuel pump pushrod, and could just as easily happened to the #7 intake. I'll check back every at the end of the day and see if anybody figured this out. Absolutly the dumbest thing I have ever done, and it will never happen again, and hopefully will save someone else the same grief.



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Just curious, what kind of money does a motor like this take to build? Also, how many do you go through in a year (average)? I'm assuming this is for your race boat, and not built to live for years?
 

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Just curious, what kind of money does a motor like this take to build? Also, how many do you go through in a year (average)? I'm assuming this is for your race boat, and not built to live for years?
I have one motor I refer to as "OLD RELIABLE" due the fact that it has had zero issues in 4 seasons. But it is basically a "mule" and isn't real competetive, although it does have more wins under it's belt than any other motor I have. A motor should last a season, (300 laps on a 1 1/4 -1 3/8 mi course)+ testing and practice, tune etc. To answer your questions, I have 4 complete long blocks, less blower and cooler built at all times. As for money....TONS:D and the motors are only 1/2 of it.



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After hooking upthe wire, the motor picked up 138 HP at 6000 rpm. But it turns out that the #2 cyl was very sick cylinder. Notice the torque drop between 5300 and 5800 on the 6400 pull sheet.
The 138 hp increase with the additional cyl is a 15.5% increase in power. I've seen 12.5-14% the couple times we've left a plug wire off. Once one popped off during a pull because of how close the plug wires were to the header there must have been an air pocket :)sphss

Sorry you lost and engine :(

Sleeper CP :D
 

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Let me make this perfectly clear.

This is a really good example of what a dyno can really do for you. In this case it is very useful. And I made this very clear in the old thread

What I don't believe is 821hp @ 7100 rpm. out of a 467
 

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steelcomp was here
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Let me make this perfectly clear.

This is a really good example of what a dyno can really do for you. In this case it is very useful. And I made this very clear in the old thread

What I don't believe is 821hp @ 7100 rpm. out of a 467
You just couldn't wait for that, could you. Not believing it is your problem...I hope it really sticks in your craw for a long time, too. :)hand
 

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As for money....TONS:D and the motors are only 1/2 of it.
Well, if you are spending "tons" on building these engines, one thing you might want to look into is cylinder pressure data acquisition. The sensor gets drilled into the head, or installed in a spark plug, and you can see actual cylinder pressure during ignition and compression. A lot to be learned there. You can get into a LCS (low cost system) with one sensor for under $5k. Take a look at http://www.tfxengine.com
 

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Well, if you are spending "tons" on building these engines, one thing you might want to look into is cylinder pressure data acquisition. The sensor gets drilled into the head, or installed in a spark plug, and you can see actual cylinder pressure during ignition and compression. A lot to be learned there. You can get into a LCS (low cost system) with one sensor for under $5k. Take a look at http://www.tfxengine.com
Very useful information can be gained from cylinder pressure analysis!
But, properly recording and putting this info to good use is ALLOT easier said than done!!!!!!!

The money these systems cost (especialy top of the line multi-cylinder systems) can be spent more wisely on allot of other things in all but the biggest high end race engine shops.

IMHO! :)sphss
 

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steelcomp was here
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Very useful information can be gained from cylinder pressure analysis!
But, properly recording and putting this info to good use is ALLOT easier said than done!!!!!!!

The money these systems cost (especialy top of the line multi-cylinder systems) can be spent more wisely on allot of other things in all but the biggest high end race engine shops.

IMHO! :)sphss
You can throw in there some boundry layer analysis and FEN on cyl. and head deflection, and some IR on flame front travel, too.:)hand
From what I understand, because of all the variables analyzing cylinder pressure can be difficult unless you're targeting a specific issue. Single cylinder one-by-one testing is very time consuming and expensive. In terms of overall expense (if you have an ongoing testing progrm that can justify it) I imagine a multi cylinder system would probably be more cost effective in terms of dyno time and man hours spent.
 

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You can throw in there some boundry layer analysis and FEN on cyl. and head deflection, and some IR on flame front travel, too.:)hand
From what I understand, because of all the variables analyzing cylinder pressure can be difficult unless you're targeting a specific issue. Single cylinder one-by-one testing is very time consuming and expensive. In terms of overall expense (if you have an ongoing testing progrm that can justify it) I imagine a multi cylinder system would probably be more cost effective in terms of dyno time and man hours spent.
On my outboard, I just plumbed all three cylinders in one head with the holes for the sensors, then had blanks made up for the other two. I originally recorded all the cylinders, one at a time, until I found the "worst case scenario" cylinder, now I just leave the sensor in there. Quite useful for building new stuff, and can show and predict problems you'd never see otherwise. I'm hoping that the system can pay for itself by saving me one blow up...after that, it's free. :)
 

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steelcomp was here
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On my outboard, I just plumbed all three cylinders in one head with the holes for the sensors, then had blanks made up for the other two. I originally recorded all the cylinders, one at a time, until I found the "worst case scenario" cylinder, now I just leave the sensor in there. Quite useful for building new stuff, and can show and predict problems you'd never see otherwise. I'm hoping that the system can pay for itself by saving me one blow up...after that, it's free. :)
I know this is taking the thread in another direction, but what did you find when you started looking at cyl pressures? Were you looking for a specific thing, or just collecting data and seing what you could find? What changes were you able to make and what gains were there?:)bulb
It sounds time consuming doing it that way, but I guess if you're just doing it for your own program it really doesn't matter.
 

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A number of things were seen by the guys at TFX - helping me interpret the data. Mainly, I just wanted a baseline of what the motor does so that as I modify it, I can see how it affects the pressure rise, rate, etc. I haven't made any changes yet, but it should gives you a ton of data to look at and make some educated assumptions from.
 

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Damn Warp, you are just too damn fast:D
To damn bad you didn't see any witness marks on the push rods. Ouch and that sucks.

GN, what engine is this Inches,cam and a blower ?

S CP :D
 

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A number of things were seen by the guys at TFX - helping me interpret the data. Mainly, I just wanted a baseline of what the motor does so that as I modify it, I can see how it affects the pressure rise, rate, etc. I haven't made any changes yet, but it should gives you a ton of data to look at and make some educated assumptions from.
It would be interesting to see what advance/retard on the timing does if it was a real engine different intake manifolds, rocker ratio and cams etc.

Sleeper CP :D
 

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Let me make this perfectly clear.

This is a really good example of what a dyno can really do for you. In this case it is very useful. And I made this very clear in the old thread

What I don't believe is 821hp @ 7100 rpm. out of a 467
This engines laying out some serious beans- nice work gn-7

Dynos dont lie-

But they dont tell the whole truth either.

Im not saying the poster isnt telling the truth, but Ive seen cheating many times. Correction factor can be a cheat. The room itself can be a cheat.

When I visited the edelbrock facility I had to lean my shoulder against the door to get into the dyno room- they had the room pressurized!

agreed this is a great example of how to use a dyno as a diagnostic tool

-but we really have no way of knowing wether this was a carbed 467 with a hydraulic roller, or an injected 623 with a 5 litre whipple on race gas.



UD
 
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