How does a Super Flow 901 dyno get the LB /H fuel consumption, is it just a calculation from the AFR & the CFM flow meter, or does it have a actual fuel flow meter ? Thanks, Charlie

A Flow meter determines volume.
An entered specific gravity figure and a fuel temp measurement allows for a volume/weight calculation in the software.

Fuel flow is displayed in lbs/hr(I’ve never looked, but you can probably display it another way if using WinDyn software)...... bsfc is calculated from observed uncorrected hp and measured fuel flow.

There should be a fuel flow turbine on the dyno. You can double check the flow turbine calibration with a gas can, a scale and a stop watch.

The flow turbine might not get used on EFI engines since it might be capable of handling high pressure. Most EFI systems have a built in flow meter so it doesn't matter. EFI systems have a lot of built in sensors which makes it much easier on the dyno.

Thanks Dwayne & Andy, a friend of mine has a race car I am helping him with, the CORRECTED #'s are very high, using the BSFC & LB/H fuel to get the uncorrected HP is much closer to the times that the car runs at the track, he is VERY disappointed, its a 500 cid Pontiac in a 78 Z28.

Yeah it can happen that way. If you know the date and location of the dyno test you can look up the local weather and figure out what the correction factor should've been. Then compare that to what the dyno shop used. Also check the inlet air temp if that is on the dyno sheet. Sometimes the shop will have the inlet air temp sensor located to close to the engine so the temp will be higher which then provides a bigger correction factor. The inlet air temp should be close to the outside air temp or a few degrees warmer. Dyno numbers are fairly easy to verify if you know what to look for.

Pretty simple really.......

You don’t race in corrected air....... and they don’t hand out corrected time slips.

If you tested on a day when there’s 10%+ correction...... that’s 10%+ you don’t have at the track.

If you had 500hp uncorrected on the dyno, and similar air at the track....... you’ll get 500hp performance....... and often...... minus whatever losses you incurred by having the motor in the car vs the dyno(drivetrain parasitic losses, under hood air, mufflers, crank driven cooling fan, etc).

If the dyno correction factors are high(which I’m sure they often are in Texas)...... those corrected numbers are just “pie in the sky”....... unless you can find some “standard day” air(60*, 29.92” baro, zero humidity) to race in.

I like to use 10% for a typical bracket car........ as a starting point.

Take the corrected power, knock 10% off...... plug that into the Moroso chart.

If the dyno correction is over 10%, I’d probably use something like 5% more than whatever the correction was, and plug that into the Moroso chart.

FWIW, I feel like the most productive way to try and tune on the dyno is to do it in similar weather to what you race in.

They used STP correction instead of SAE

Uncorrected

633.5hp@6000...... so......damn close to 10% correction.

Plus that pull is done with water temps that are going to be pretty hard to duplicate at the track.
And, depending on the combo and the tune...... that could easily be another 10-20hp you wouldn’t have in the car.

The pulls, and tuning should be done at the actual operating water temps.

I can see where the ET’s would coincide with numbers closer to 580-600hp.

Dang........ that air temp is pretty unfriendly.

If you have the whole dyno sheet there should be a correction factor on there. See if they used the correct correction factor. Maybe they did but the weather was really bad like Dwayne said. If that is the case then it is what it is. If they used the wrong correction factor then that is a different clue.

The real question is what are you trying to do? Are you trying to tune the car or trying to verify the dyno numbers? Do you want to confirm the dyno is working properly or focus on tuning the car?

I agree, the water temp numbers are either wrong or just stupid. The average bracket engine should not be run on a dyno at 110 degrees. Maybe a pro type race engine that is designed to run at 100 degrees but a normal engine should not be pulled when cold. The temp sensor is either wrong or else the shop was trying to fudge the numbers. I'm not sure which. A typical bracket car will go down the track with the engine at 160 or 180 so that is how it should be tuned and tested. We'll dyno boat motors at a lower temp since they pick up cold water from the lake but we never test car engines that cold.

Your friend may need to work on the chassis and drivetrain to make the car faster with the motor the way it is, what do the time slips and spark plugs look like?
On the BSFC it looks a little rich, especially above 5000 RPM, maybe try leaning it down a smidge to see if the MPH picks up or not
If it does and the 60 ft. get worst then traction maybe limiting the cars times
Torque converters in a race car can really hold the car back, compare his time slips to other similar cars at the track during the same time frame to see if that will help or not
I've also seen fuel delivery systems limit cars that the owners didn't thank it was, can you fatten the jetting up enough to slow the 1/4 MPH down? If not fix that next
How heavy is the car and what is it running ET and MPH on what length tracks?

Air temp of 102 is hot. Was it really that hot that day or did they move the sensor over close to the headers? That is why the correction factor is so high.

And I'd like to know how the water temp was only 110 when the air temp was 102? That doesn't really make sense.

His now race car is no faster than his 525 hp street car 1978 Trans Am, he was thinking a low 10 car, in good air its been 10.8 @ 124, 3600 lb race weight , when we rent the track again we will do some tuning, we put a looser converter in it, will also work on my Charger when we go.

Yes that is a typical summer day here in Southeast Texas

Car performance and dyno power are two totally different things. Some cars can put the power to the ground but most can't. You have to figure out what problem you are trying to solve.

I’ll often do a low water temp pull at the end of the session for the “hero pull”.

Here’s an example of what I see as fairly typical.......
Corrected power- 652hp
Uncorrected power- 632hp
Moroso chart power based on actual weight/mph at track- 605hp

I have a few customers who have the numbers closer than that....... but frankly, most are worse.

Okay, if the air temp was 102 then a 10% correction factor is very realistic, maybe even low. But the water temp of 110 degrees doesn't make any sense. There is zero chance that a bracket car cooling system will operate at 110 degrees when the air temp is 102. He will be lucky to run that engine at anything less than 180 degrees when it is that hot outside. Either the temp gauge on the dyno was broken or the dyno operator was trying to fudge the numbers. I don't know which but it doesn't make any sense. 80 degrees of engine temp can make a big difference. How hot does the engine run at the track?

That does seem correct, it has a full 3 1/2 exhaust, air filter, clutch fan, it was dead hooking, 1.75 60ft, we did a converter change, installed electric fans, our track will open back up at the end of this month, he said to me WTH your heavy a$$ street car Charger MPH is about the same as this car.

185-195