Rolling Road / Dyno

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John Clarke
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Rolling Road / Dyno

#1 Post by John Clarke »

Hi Gang.
Our 912 Engine (616/40) running in the 356 Coupe has had 86mm Shasta Barrels and Pistons fitted earlier this year. Heads refurbished. (Stock)
Running with Dellorto 40 DRLA Carbs. Bursch Exhaust. Would like to get an accurate reading of what it is putting out. But not sure if it is a bit cruel on the engine to endure the Rolling Road / Dyno session.
Good or Bad. What's the verdict ? It sounds punishing when put under load !
Greatfull for any Input on this.
Regards Jay
 

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Mike Wilson
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Re: Rolling Road / Dyno

#2 Post by Mike Wilson »

I've had my '63 on a rolling road/chassis dyno a coupe of times when John Willhoit had one available at his open houses. No problems at all.

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Re: Rolling Road / Dyno

#3 Post by C J Murray »

It is no more stressful than doing the same on the road.
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Re: Rolling Road / Dyno

#4 Post by Doug McDonnell »

Looking at Willhoit's Dyno Data will maybe get you close if you know your Cam and compression ratio: http://www.willhoitautorestoration.com/ ... 202008.pdf
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Re: Rolling Road / Dyno

#5 Post by Al Zim »

Zim's dyno's most every engine we rebuild. It would be interesting for you to post the Dyno runs to see what you get. I am betting 75 to 80 Horsepower with the power curve ending at 4,900 RPM. It is well worth the $500. +++ to see what you really have. Checking output of the engine by adjusting the timing (easily done on the Dyno) probably will help you find additional horsepower.
Last edited by Al Zim on Sun Sep 18, 2022 11:35 am, edited 1 time in total.
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Re: Rolling Road / Dyno

#6 Post by Mike Wilson »

I was thinking my newer cars essentially go on rolling chassis dynos when they need to be smog checked. No problems.

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Re: Rolling Road / Dyno

#7 Post by John Clarke »

Al 75 to 80 that's not good!
A few years ago when we were dialling in the Dellortos and the 031Dizzy , running with the Street Quiet Bursch system we were getting 96bhp on the rolling Road ! So with the addition of the larger 86 mm barrels we can expect 75 -80 bhp I'd say that's disappointing
Regards Jay
 

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Re: Rolling Road / Dyno

#8 Post by Martin Benade »

Hp numbers from different dynos aren’t necessarily comparable. Better for noting increases from a baseline.
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Re: Rolling Road / Dyno

#9 Post by John Brooks »

I have been working/Building an engine DYNO of and off for a couple tears, I am using an Eddie Current Brake ( electromagnetic load) for engine load. Its been a slow process other things keep getting in the way. But if calibrated correctly, the load cell measuring the torque and the RPM are correct all the DYNOs should read out the same horse power. I wanted a load for seating new rings and to break in new engine builds. Just something that would put 20-30 pounds of drag on the new motor for brake in. After all the brain cramps from the math and trying to measure the magnetic flux on a variable DC power source, I found its really not all that hard, just time consuming. I can get well over 150 Ft-lbs of load out of the system. By adding more energized coils and varying the current you can really dial in a load, from nothing to stall the engine.
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616/xx  Engine DYNO for engine run-in
616/xx Engine DYNO for engine run-in
electromagnet coil packs for the Eddie Current Brake. turned on in pairs
electromagnet coil packs for the Eddie Current Brake. turned on in pairs
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John Clarke
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Re: Rolling Road / Dyno

#10 Post by John Clarke »

Hi John
You are a clever in guy. You lost me. But it all sounds impressive. Tell me about things getting in the way 😁
Everyone. Shouldn't ALL Dynos be calibrated to read the same? Cheers Jay
 

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Re: Rolling Road / Dyno

#11 Post by Harlan Halsey »

All dynos are calibrated. It is the operator, the owner and the atmosphere which are not. The owner/builder and the operator usually want to see the highest number they can particularly if it is a street engine they are tuning. Race engine builders want maximum usable HP measured at the end of the straight. So they run the dyno differently. Years ago when 356s were the kings of E Production and Chuck Forge regularly won the Division, one year he went to the runoffs at Road Atlanta. No 356 was faster down the straight. The most power his engine(s) recorded on the Cal Dyno was 145 HP. Others at that runoff were claiming up to 180 HP!
Dynos are very useful development and tuning tools, but comparisons between different dyno measured powers are much less useful.

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Re: Rolling Road / Dyno

#12 Post by C J Murray »

DynoJet chassis dynos are popular and the numbers make sense when teesting brand new cars vs the claimed numbers. Divide the wheel HP by .85 To estimate the crankshaft HP. They are very consistent from location to location so a DynoJet number in CA is very close to the number in PA. They also have automated weather stations that adjusts for weather changes.

Two of my favorite dyno sheets, one showing the exact same engine before and after rebuild and the other showing two different engines built by me with different goals in mind. As others have said the dyno is best used to check engine development improvements.
9-22-2008 8;56;06 AM.jpeg
9-22-2008 8;59;43 AM.jpeg
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