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Disappointing day on the dyno

Engine dyno for first numbers. Chassis dyno will tell how well you're setup is working later. The numbers from the engine dyno, weight, and ET slips....do the same
 
Did y'all play with the timing, jetting etc? And even if the stall is on the low side, I would think the engine would still pull through it once isn't slipping anymore. I mean, what would they say if the car had a stick in it?? I would hope the trans would be in high gear by 5500 anyways.
 
Cranky said:
Did y'all play with the timing, jetting etc? And even if the stall is on the low side, I would think the engine would still pull through it once isn't slipping anymore. I mean, what would they say if the car had a stick in it?? I would hope the trans would be in high gear by 5500 anyways.
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There was no playing with anything in the format they had. Three consecutive pulls with no changes in between. All pulls were made in high gear.
 
hard to read that chart. Did they hook up the exhaust O2 and graph the output.
I have seen some dyno pulls where the fuel mixture was way off and varied alot through the RPM range.
One guy with a Oldsmobile (Edelbrock heads and mechanical fuel pump) had an issue with this carb float. At idle/low RPM everything seemed fine, at high RPM fuel was coming out of the fuel bowl. As I recall, dyno curve looked good to about 3,000 RPM and then nose dived when the extra fuel made the mixture super rich. Lucky no fire from all the fuel.
 
Sweet5ltr said:
It almost seems like you're down a cylinder. Car should easily make 500rwhp on its worst day, even on a mustang dyno. Graph seems accurate, spread is correct between peaks. I'm just surprised the torque peak is so low (which is why the results are disappointing), even with 526ci, should be at least 750-1000 rpm higher (I would imagine). 380 cfm of airflow @ .700 lift, something is SERIOUSLY wrong here for it to have a torque peak @ 4100 rpm with max-wedge port heads. Converter seems way off for this combination.
Click to expand...
After everything cooled down I pulled all the plugs to see if I was down a cylinder and they all looked ok from what I could see. A little rich maybe but not horrible (see picture below). I really don't understand the numbers at all because everything is so far off. Besides the torque being early and low, the curve was nowhere near as flat as it should be. The converter was just built for this combo by Lenny at Ultimate with all the specs for the motor known ahead of time so based on his reputation I wouldn't think it would be that far off. We spec'd the converter for a 3800-4000 stall so it seems a little suspicious that this is where the dyno stops showing any additional gains. I'll call Lenny on Monday and see what he thinks. At this point I think I am just going to assume the test was completely bogus since I don't have any other indicators that something else is wrong. I'll run a leakdown test to be sure.

20171007_213601.jpg
 
451Mopar said:
hard to read that chart. Did they hook up the exhaust O2 and graph the output.
I have seen some dyno pulls where the fuel mixture was way off and varied alot through the RPM range.
One guy with a Oldsmobile (Edelbrock heads and mechanical fuel pump) had an issue with this carb float. At idle/low RPM everything seemed fine, at high RPM fuel was coming out of the fuel bowl. As I recall, dyno curve looked good to about 3,000 RPM and then nose dived when the extra fuel made the mixture super rich. Lucky no fire from all the fuel.
Click to expand...
They did not but I don't think that is likely. If anything, reading the plugs it looks like the midrange might be a little lean.

20171007_215327.jpg
 
Brewzer67 said:
There was no playing with anything in the format they had. Three consecutive pulls with no changes in between. All pulls were made in high gear.
Click to expand...
What I meant by the high gear remark is that even with a stick, you're going to be in high gear....1 to 1 total lockup so imo, the converter shouldn't matter that much once the engine is up in the rpm range. Now if the converter keeps on slipping throughout the pull, then you need a better converter and may be part of the reason for soft numbers. Yeah, most will slip some but not enough to change the numbers that much. My dyno was the drag strip so I might be talking through my butt but even on the track, you knew if the converter was doing it's job or not and I would think you or the dyno operator would also know during a pull. At least the math could be figured out. On an engine dyno, you're not going to use a torque converter. To me, even a stock converter with total lockup behind a healthy high performance engine isn't going to rob peak horsepower/torque numbers, however, it will hurt you on the launch at the track. On a chassis dyno, a near stock or slipping converter will generally show lousy numbers down low until the engine gets up into it's range and then it will/should overcome a low stall speed converter and post good numbers....IF the converter is good. I've run plenty of cars with healthy engines with near stock converters because they were going to be daily drivers. They were pretty slow off the line but made up for it once the engine got into it's power band.....kinda like a 2 stroke dirt bike does.
 
Card reads 526HP at 6,000 and 487 Ft/lbs at 5350 ..........That engine needs a MUCH larger carb......
Larger carb will bring torque peak up and make HP a much flatter curve...
Car runs 10.50 at 129 mph and is also street legal.. I do run an 8 3/4
 
splicer said:
Card reads 526HP at 6,000 and 487 Ft/lbs at 5350 ..........That engine needs a MUCH larger carb......
Larger carb will bring torque peak up and make HP a much flatter curve...
Car runs 10.50 at 129 mph and is also street legal.. I do run an 8 3/4
Click to expand...
I am THE BELIEVER in 1050 Dominators for 500"+ Mopar BB motors. I had an 850 Mighty Demon on my Edelbrock Single Plane Intake and went 10.98, then all I did was bolt on a 4150 to 4500 Adapter onto my 4150 Edelbrock Single Plane. Same day, same track, only an hour apart....With the 850 Mighty Demon it went 10.98 then after bolting on the 1050 Dom it went 10.63 all day long in the low, low 10.60s. Over 3/10 of a second...need I say more.

012.jpg 014.jpg
The Dominator is the SPORTSMAN SERIES DOMINATOR from Summit,Only $799.
Then, as we all end up doing, I continued to upgrade the motor. Went to an INDY Max Wedge Dominator Single Plane Intake Manifold (ported) and ported my INDY SEZ heads as well as take them out to MAX WEDGE Size (they were standard port when I went 10.60's.) and now car is going in the mid 10.30's and 129MPH +. I expect 10.20's at 130+mph at the next race in October when we have good air.

max 5.jpg
 
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Ok
Heres a couple of my dyno runs .
MIA dyno in 2013 440ci
Tilleys Racing dyno 2017 505ci
Both pull till stall then flat but motor happily reved to self imposed redline . 6500 for 440 7000 for 505
Just an anomally that will show sometimes with autos

Tex

20171009_100610.jpg 20171009_100627.jpg
 
I'm also a firm believer in mucho carbs. After all, my old car went 10.60's in 84 with a fairly mild engine with a TR and 750 carbs.....
 
DJ, would smaller jets decrease the cfm on the 660's? (Sorry I don't mean to hijack thread here).
 
LOL....I guess you got your answer. Jets do not reduce CFM....just fuel and a good mix with air flow is what you are after.
 
Thanks for all the input. I'll try to post a video as soon as I can figure out how to shrink it in size some.
 
Food for thought just for comparison. The sum of the correct parts = HP. Buddy with 540 BBC 10.25-1 compression Dart pro 1 Fully cnc heads matching intake, Crane .714 bracket roller cam and 950 holley Hp. 825 HP and 725 TQ on engine dyno. He knows motor would make more power with Dominator 4500 series carb but he drives this on the highway to car shows as well as races it. On the Bottle motor made 1125 HP car runs 8.98 in a 3600 lb Nova.

Toss that 850 demon carb on the next swap meet table for one, you should be running an 950 on that motor.

I ran my 426 low deck on the engine dyno after it was built. 383 + 440 Crank = 426. I stayed on the small side with everything, as i was looking for torque and drivability. Eddy rpm performer heads 220 cc intake runner, RPM dual plane intake 10.0-1 compression and lunati solid lifter cam. .544/.566 .241/.253 @ .050. Made 525 hp and 552 tq. motor revs like a small block makes power to 6000 rpm. I am running an AED 750 HOM carb. flows to 830 cfm. Motor only used 630 cfm. The thing is very crisp and has great throttle response. I have had every engine i have built on the Engine dyno, it doesnt lie and you will find your mistakes and miss matched parts pretty fast.
 
I learned this the hard way.
Demon carbs are rated wet.
Look at the venturi size, an 850 Demon probably flows as much or more than a 950 dry flowed.
The best way to tell if a carb is undersized, is see what kind of vacuum it's pulling under WOT.
I have an 850 Demon on my 526, I'd bet OPs carb is not far off from what he needs.
 
Last edited:
Brewzer67, Question,Have you driven the car ? What does the seat of your pants tell you ?
 
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