skewing the dyno??

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MOPARMAGA said:
That's funny because when I dyno'd my engine I gained 26 hp from a header swap, 2 inch to 2 inch / 2-1/8 step headers ....then I wanted to run the exhaust as it would be in the car, so we removed the dyno exhaust....it picked up another 25 hp.... So, that's a 51 HP pick up total.
There was no messing with anything except for removing a restriction.
I'll be putting this engine back on the Dyno soon if you need proof.
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Your "too small" dyno exhaust is a perfect example of why dyno numbers can vary from dyno to dyno. And it has nothing to do with dishonesty, fudging numbers, Incorrect weather correction or incorrect dyno calibration. Just a case of operator error (we all error sometimes) by using the wrong diameter (too small) dyno exhaust for the horsepower output of the engine. You should be able to pull the engine with the dyno exhaust on or off and it should repeat the number both ways. If you're doing header testing it's not a bad idea to make sure you test your dyno exhaust first. Otherwise your just testing for which header is best with your dyno exhaust system. Also when testing without dyno exhaust you have to make sure you have adequate airflow to keep your dyno room swept out of exhaust gasses so you don't gas out yourself or have the engine sucking the gasses in. It's best to use a pusher fan and a puller fan at each end of the room so you can move the needed amount of air through the room and be able to adjust the fanspeeds to keep the room at zero static pressure. The engine should also supplied with its own clean air that is the appropriate temperature and humidity for the conditions the engine will be used at. Like a 2.5' tube not a 8" tube. The air temp , humidity and air pressure probes should be in this tube as close to the carb as possible. That air should be supplied at high volume and low velocity and not sealed to the carburetor. Also when tuning make sure you use the air cleaner set up that will be on the engine. Sometimes budget , time or other obstacles will keep you from testing the way you should or want to. Be aware that how you test might affect your results and then do the best you can.
Crap, too long.
 
We have 32 Dyno's. All are SAE calibrated for all of our OEM work. On the racing side of things, we have done several back to back tests over the years against other people's "happy" dyno's. Only to disappoint alot of customers. Showing them what their engines truly make for power and torque. Sometimes it can be well over 100 horsepower and ft/lbs of torque.
Many single dyno type shops can manipulate there dyno to give the customers close to the numbers they were hoping for.

Here is one on mine on one of our Dyno's.

20160429_111243 (002).jpg


20160429_111251 (002).jpg
 
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92b said:
Your "too small" dyno exhaust is a perfect example of why dyno numbers can vary from dyno to dyno. And it has nothing to do with dishonesty, fudging numbers, Incorrect weather correction or incorrect dyno calibration. Just a case of operator error (we all error sometimes) by using the wrong diameter (too small) dyno exhaust for the horsepower output of the engine. You should be able to pull the engine with the dyno exhaust on or off and it should repeat the number both ways. If you're doing header testing it's not a bad idea to make sure you test your dyno exhaust first. Otherwise your just testing for which header is best with your dyno exhaust system. Also when testing without dyno exhaust you have to make sure you have adequate airflow to keep your dyno room swept out of exhaust gasses so you don't gas out yourself or have the engine sucking the gasses in. It's best to use a pusher fan and a puller fan at each end of the room so you can move the needed amount of air through the room and be able to adjust the fanspeeds to keep the room at zero static pressure. The engine should also supplied with its own clean air that is the appropriate temperature and humidity for the conditions the engine will be used at. Like a 2.5' tube not a 8" tube. The air temp , humidity and air pressure probes should be in this tube as close to the carb as possible. That air should be supplied at high volume and low velocity and not sealed to the carburetor. Also when tuning make sure you use the air cleaner set up that will be on the engine. Sometimes budget , time or other obstacles will keep you from testing the way you should or want to. Be aware that how you test might affect your results and then do the best you can.
Crap, too long.
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That's good info thanks.
 
92b said:
Your "too small" dyno exhaust is a perfect example of why dyno numbers can vary from dyno to dyno. And it has nothing to do with dishonesty, fudging numbers, Incorrect weather correction or incorrect dyno calibration. Just a case of operator error (we all error sometimes) by using the wrong diameter (too small) dyno exhaust for the horsepower output of the engine. You should be able to pull the engine with the dyno exhaust on or off and it should repeat the number both ways. If you're doing header testing it's not a bad idea to make sure you test your dyno exhaust first. Otherwise your just testing for which header is best with your dyno exhaust system. Also when testing without dyno exhaust you have to make sure you have adequate airflow to keep your dyno room swept out of exhaust gasses so you don't gas out yourself or have the engine sucking the gasses in. It's best to use a pusher fan and a puller fan at each end of the room so you can move the needed amount of air through the room and be able to adjust the fanspeeds to keep the room at zero static pressure. The engine should also supplied with its own clean air that is the appropriate temperature and humidity for the conditions the engine will be used at. Like a 2.5' tube not a 8" tube. The air temp , humidity and air pressure probes should be in this tube as close to the carb as possible. That air should be supplied at high volume and low velocity and not sealed to the carburetor. Also when tuning make sure you use the air cleaner set up that will be on the engine. Sometimes budget , time or other obstacles will keep you from testing the way you should or want to. Be aware that how you test might affect your results and then do the best you can.
Crap, too long.
Click to expand...


I bought the size of exhaust and mufflers I could get.

I wanted 10 inch pipe and mufflers. Couldn’t get them.

So I get how it works and no bullshit was going on.

It is what it is and eventually I’ll get the big size.

But know this. The exhaust was ON for ALL the testing.

That means the junk headers are junk headers no matter what.
 
Newbomb Turk said:
I bought the size of exhaust and mufflers I could get.

I wanted 10 inch pipe and mufflers. Couldn’t get them.

So I get how it works and no bullshit was going on.

It is what it is and eventually I’ll get the big size.

But know this. The exhaust was ON for ALL the testing.

That means the junk headers are junk headers no matter what.
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Yep, I just did mine like that to duplicate in car exhaust. Very loud.
 
Newbomb Turk said:
I bought the size of exhaust and mufflers I could get.

I wanted 10 inch pipe and mufflers. Couldn’t get them.

So I get how it works and no bullshit was going on.

It is what it is and eventually I’ll get the big size.

But know this. The exhaust was ON for ALL the testing.

That means the junk headers are junk headers no matter what.
Click to expand...
What brand 10" dyno mufflers was it that you were looking at that you couldn't get?
 
92b said:
What brand 10" dyno mufflers was it that you were looking at that you couldn't get?
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I don’t remember now. They were hospital rated or something like that.

They were 10 in and 10 out. Couldn’t by the pipe either


They had nothing in 8 inch for pipe but I later found out if the mufflers had an application like earth moving equipment or OTR trucks you weren’t getting any muffler bigger than 6 inches without a PO that showed your company and end use.

That and other stuff like certain hoses used in heavy industries and such.

They were protecting certain industries to keep them from going without if the supply chain got worse than it was.

Oil and air filters was another. Once you got to a certain size if you didn’t fit the industry you didn’t get them.

Edit: I forgot to mention getting the pumps was a giant mother too. By the time I knew I needed the pumps you had to wait because nothing was in inventory and they were building them to order.

They had a shortage of seals and junk like that. I needed two pumps. I was told at one point they were only building pumps for standing customers.

I even tried to find a standing customer that would put my pumps on their orders. Didn’t happen.
 
I wonder what the going rate for a "Dyno Day" is these days..... ???? ..
 

318willrun said:
I wonder what the going rate for a "Dyno Day" is these days..... ???? ..
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I’m charging 750 for the first day. That includes getting on and off the dyno, break in, filter checks, lash loops and jet changes.

If you require me to get into the carb for emulsion changes it’s an extra 100 bucks for a single 4 and 150 for two fours.

If you want me to do timing curve measurements that’s an extra 200 dollars and that includes getting a custom curve in your distributor.

For the latter stuff with all the tuning you really need two days to do it right. So it’s 1200 for two days and I cut the above costs in half.

To really do the tuning it takes two full days especially if we are breaking in a cam and we have to install inner springs and such.

Time goes by fast.

If all you want to do is break in the cam/engine, verify no leaks and make some power pulls and make jetting changes you can do it in one day.

I will say if things go sideways like oil leaks and the like it eats up time real quick. So if you are assembling the engine getting it sealed is a big deal. You can eat up a ton of time pulling an intake, doing all the clean up and prep and resealing it.

You can test intakes and headers and carbs and spacers. I’ll make as many pulls as you want in a day but making maximum pulls isn’t as important as seriously considering the data coming off the dyno and making correct tuning changes.

And when the conformation bias camel gets his nose in the tent you know it won’t be long before he’s all the way in and taking you down some Alice In Wonderland rabbit holes.

That really wastes time.

BTDT and donkey kicked myself in the nuts several times for allowing myself to bullshit myself.
 
Newbomb Turk said:
I’m charging 750 for the first day. That includes getting on and off the dyno, break in, filter checks, lash loops and jet changes.

If you require me to get into the carb for emulsion changes it’s an extra 100 bucks for a single 4 and 150 for two fours.

If you want me to do timing curve measurements that’s an extra 200 dollars and that includes getting a custom curve in your distributor.

For the latter stuff with all the tuning you really need two days to do it right. So it’s 1200 for two days and I cut the above costs in half.

To really do the tuning it takes two full days especially if we are breaking in a cam and we have to install inner springs and such.

Time goes by fast.

If all you want to do is break in the cam/engine, verify no leaks and make some power pulls and make jetting changes you can do it in one day.

I will say if things go sideways like oil leaks and the like it eats up time real quick. So if you are assembling the engine getting it sealed is a big deal. You can eat up a ton of time pulling an intake, doing all the clean up and prep and resealing it.

You can test intakes and headers and carbs and spacers. I’ll make as many pulls as you want in a day but making maximum pulls isn’t as important as seriously considering the data coming off the dyno and making correct tuning changes.
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Thanks. Myself, I would run the engine on a run stand to break the cam in and verify no leaks before dyno day. Then, the dyno day would be for pulls and tuning.
 
318willrun said:
Thanks. Myself, I would run the engine on a run stand to break the cam in and verify no leaks before dyno day. Then, the dyno day would be for pulls and tuning.
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That is certainly the smart, efficient and cost effective way to do it.

I suggest that to anyone who can do it to do it. It’s a huge time and money saver.

Nothing is worse than paying for dyno time to change a rear main seal.
 
Newbomb Turk said:
I’m charging 750 for the first day. That includes getting on and off the dyno, break in, filter checks, lash loops and jet changes.

If you require me to get into the carb for emulsion changes it’s an extra 100 bucks for a single 4 and 150 for two fours.

If you want me to do timing curve measurements that’s an extra 200 dollars and that includes getting a custom curve in your distributor.

For the latter stuff with all the tuning you really need two days to do it right. So it’s 1200 for two days and I cut the above costs in half.

To really do the tuning it takes two full days especially if we are breaking in a cam and we have to install inner springs and such.

Time goes by fast.

If all you want to do is break in the cam/engine, verify no leaks and make some power pulls and make jetting changes you can do it in one day.

I will say if things go sideways like oil leaks and the like it eats up time real quick. So if you are assembling the engine getting it sealed is a big deal. You can eat up a ton of time pulling an intake, doing all the clean up and prep and resealing it.

You can test intakes and headers and carbs and spacers. I’ll make as many pulls as you want in a day but making maximum pulls isn’t as important as seriously considering the data coming off the dyno and making correct tuning changes.

And when the conformation bias camel gets his nose in the tent you know it won’t be long before he’s all the way in and taking you down some Alice In Wonderland rabbit holes.

That really wastes time.

BTDT and donkey kicked myself in the nuts several times for allowing myself to bullshit myself.
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That’s cheep. When I used dude in Portland it was 1,000 plus gas and he didn’t do ****. That was 2019…

I have to buy / make an adapter for my brothers dyno to run my junk.
 
Scody21 said:
Yeah, but where’s the load on the run stands?
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No load but at least the cam is in and it has no oil leaks of course if you use Line2Line coatings like I do I’d skip the run in stand.

To bed the pistons in with that coating on them takes load. It’s nicer if you don’t have to break in the cam while doing the pistons but I break in the cam with some load and rpm changes while I’m doing it.
 
Newbomb Turk said:
No load but at least the cam is in and it has no oil leaks of course if you use Line2Line coatings like I do I’d skip the run in stand.

To bed the pistons in with that coating on them takes load. It’s nicer if you don’t have to break in the cam while doing the pistons but I break in the cam with some load and rpm changes while I’m doing it.
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You can always ask you neighbor to hold on to the flywheel when it's running... always works.
 
318willrun said:
Dyno is a great tool. To me, one of the best chassis dyno's out there is the drag strip and ET slip.
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I have to agree, it’s nice to see the torque and power curves of cams and intakes. There great to compare and determine the converter and get a baseline on timing and the carb. But the Plymouth has a scoop that gets clean air and is sealed to the carb, what I have found it likes two degrees more timing and a couple more numbers of jet for a few mph on the 1/4 mile dyno.
 
Newbomb Turk said:
I’m charging 750 for the first day. That includes getting on and off the dyno, break in, filter checks, lash loops and jet changes.

If you require me to get into the carb for emulsion changes it’s an extra 100 bucks for a single 4 and 150 for two fours.

If you want me to do timing curve measurements that’s an extra 200 dollars and that includes getting a custom curve in your distributor.

For the latter stuff with all the tuning you really need two days to do it right. So it’s 1200 for two days and I cut the above costs in half.

To really do the tuning it takes two full days especially if we are breaking in a cam and we have to install inner springs and such.

Time goes by fast.

If all you want to do is break in the cam/engine, verify no leaks and make some power pulls and make jetting changes you can do it in one day.

I will say if things go sideways like oil leaks and the like it eats up time real quick. So if you are assembling the engine getting it sealed is a big deal. You can eat up a ton of time pulling an intake, doing all the clean up and prep and resealing it.

You can test intakes and headers and carbs and spacers. I’ll make as many pulls as you want in a day but making maximum pulls isn’t as important as seriously considering the data coming off the dyno and making correct tuning changes.

And when the conformation bias camel gets his nose in the tent you know it won’t be long before he’s all the way in and taking you down some Alice In Wonderland rabbit holes.

That really wastes time.

BTDT and donkey kicked myself in the nuts several times for allowing myself to bullshit myself.
Click to expand...
Show us some pictures of your dyno. We love pictures around here.
 
92b said:
Show us some pictures of your dyno. We love pictures around here.
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I will when I get home. I have some on my phone but they aren’t too good.

Screw it. I’m sitting at the bank with my mom. When we finish here and I get back to the house I’ll look through the pictures on here and post the best of what I have.

I may have some videos on here too buck I know those suck buttermilk
 
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