One thing nice about a dyno test is you get a baseline for peak horsepower and torque. You can choose tire size, rear gear, and converter accordingly. It's a tool!
Dyno Vs.Drag Strip Testing
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PRH
Well-Known Member
I don’t see any nascar/pro stock/comp teams getting rid of their dynos any time soon.
Most record setting stock/super stock builds have been sorted out on the dyno as well.
It’s not an argument I engage in any longer.
Don’t want to spend the money on dyno time? Then don’t.
Simple as that.
Most record setting stock/super stock builds have been sorted out on the dyno as well.
It’s not an argument I engage in any longer.
Don’t want to spend the money on dyno time? Then don’t.
Simple as that.
33IMP
Well-Known Member
An engine dyno is a tool to get the most power out of an engine combo.
A dragstrip is a tool to get the most out of the rest of the combo, converter, gearing suspension, driving technique, etc.
What i find amusing is how many think a big dyno number by itself means their car is fast, or it SHOULD be. This, without optimising the rest of the combo. There is a difference between a streetcar with 500 hp, 3.23 gears 3800 lbs, and street tires, and 500hp, 5000 converter, 4.10 gears, 3000 lbs and slicks. 500 hp doesnt guarantee anything.
A dragstrip is a tool to get the most out of the rest of the combo, converter, gearing suspension, driving technique, etc.
What i find amusing is how many think a big dyno number by itself means their car is fast, or it SHOULD be. This, without optimising the rest of the combo. There is a difference between a streetcar with 500 hp, 3.23 gears 3800 lbs, and street tires, and 500hp, 5000 converter, 4.10 gears, 3000 lbs and slicks. 500 hp doesnt guarantee anything.
My experience has been the four motors I have dynod the info gained and problems solved saved many days at the track. I use dyno time to get baseline info. I changed a pill in my injector and got the high speed fuel curve spot on on a dyno. I would doubt I could have done that at a track. Way too many variables to contend with there. Don't believe dyno time is worth the time? Have a ball figuring out at the track with traction changes, weather changes, gusts of wind, and the efficiency of the driveline and tires affecting all the info you get on a time slip.
My last small gains were like 4 or 5 hp per change on a 926 hp motor. That equates to .012 ET change on an 8.80 car! You can't accurately judge the effects of a change like a dyno reading. Been there, done it both ways over fifty years.
My last small gains were like 4 or 5 hp per change on a 926 hp motor. That equates to .012 ET change on an 8.80 car! You can't accurately judge the effects of a change like a dyno reading. Been there, done it both ways over fifty years.
yellow rose
Overnight Sensation
The BEST answer yet. Any calculator is a very best case scenario.
Roughly, how much difference in HP from the dyno to the time slip? Just curious.
You’d be surprised the number of guys who dyno something and put it in the car and the car is junk.
I had a customer running his mouth about my dyno numbers so I went to the track to see what the hell was going on.
First pass and anyone with the IQ of a bag of hair could see the converter was toast. This guy was swapping carbs, borrowing ignition boxes, changing valve lash...about everything under the sun. And the time slip never changed.
He didn’t want to hear the truth. His high dollar converter wasn't right. It couldn’t be the converter. He called the converter people and they said it was fine. It had to be the dyno lied.
After few weeks last he came by the shop to apologize and said I was right, the converter was junk. I said are you going down to the track and right before first round and publicly announcing that it wasn’t my engine, or tune up, or the dyno that was junk, but the converter all along.
Of course, he didn’t do that.
I could type all day the crap guys do and the engine builder/dyno get blamed for stuff not running.
yellow rose
Overnight Sensation
yellow rose
Overnight Sensation
The dyno is much easier on the engine than the track is.
You can figure out how long any dyno pull will last one the stick is down.
Just figure 600 RPM per second and then calculate the time from the RPM you are starting the pull to the RPM at the end of the pull you’ll see how long it takes.
Of course, this only works with a water brake dyno. An inertia dyno (talking engine dyno’s not wheel dyno’s) won’t have a set rate of acceleration.
I’ll be using an inertia dyno.
I don’t get how some feel a dyno is hype machine and some formula they find on the internet is more accurate in telling you how much power you make.
How did they come up with the formula in the 1st place ??
But yes I get it, it’s the performance on the street or track that ultimately matters
How did they come up with the formula in the 1st place ??
But yes I get it, it’s the performance on the street or track that ultimately matters
33IMP
Well-Known Member
I saw that converter problem too. We had a racer at my local track with a nicely built early fifties chevy with a small inch sprint car motor that he was spinning to eight grand. Problem was , it left at eight grand and stayed there the whole way down the track. You literally couldnt hear an rpm change at the gear change! I think everybody at the track that tried to help him told him his converter was not just wrong, but completely garbage too.
When he finally changed it, i think his car picked up something like six tenths in the eighth.
When he finally changed it, i think his car picked up something like six tenths in the eighth.
33IMP
Well-Known Member
Love the Carnac reference. Here's my favorite, slightly modified for a mopar forum.
Sis, boom, waaaannnhh!
Describe the sound made when a chevy explodes.
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A buddy of mine attends quite a few flash-light drags around here, they are close and cheap to participate in, but no times.
Closest drag strip is 3 hrs away
There is a local guy that set up a chassis dyno in his garage, he charges $40 for three pulls.
After the first pull, the first thing he said, "Your converter is wrong, you are driving thru it"
He still made 420 HP at the rear wheels, but immediately changed the converter, and it made a huge difference in how the car drove.
Closest drag strip is 3 hrs away
There is a local guy that set up a chassis dyno in his garage, he charges $40 for three pulls.
After the first pull, the first thing he said, "Your converter is wrong, you are driving thru it"
He still made 420 HP at the rear wheels, but immediately changed the converter, and it made a huge difference in how the car drove.
I think the problem most have with dynos, is it often points to problems in the car they put it in. Just as YR says.
This agonizing scenario has played out more often than not. It was a reality I've had to face myself.
In 93, I replaced a junk GER converter with an old 9J, turned a 13 sec car into a 11 sec car overnight and found my missing 100 hp.
On another front... every trans has different losses, or diffs for that matter. Road alignments are not drag friendly.
When a dyno shows 500hp, your drivetrain does not see it. It see's the hp available in the gear changes.
Example: On my car, that is 4700 (converter) to 6500 and 5300 to 6500 x 2. (Fun to get groceries with too)
This agonizing scenario has played out more often than not. It was a reality I've had to face myself.
In 93, I replaced a junk GER converter with an old 9J, turned a 13 sec car into a 11 sec car overnight and found my missing 100 hp.
On another front... every trans has different losses, or diffs for that matter. Road alignments are not drag friendly.
When a dyno shows 500hp, your drivetrain does not see it. It see's the hp available in the gear changes.
Example: On my car, that is 4700 (converter) to 6500 and 5300 to 6500 x 2. (Fun to get groceries with too)
j par
Well-hung Member
My favorite one so far is it saves time at the track? Lol isn't that what we built them for?... LOL...
ir3333
Well-Known Member
i have no horse in this race...i don't drag my cars.
But you dyno guys would have to return to the dyno every time you make a change to see what it did and i doubt if that happens unless it's your profession.A life long local racer who has raced everything from small blocks to Hemis had little use for a dyno and in his book he wrote the highest horsepower engines never et'd well. Always made his changes based on the total package,logic and experience... then went the track.
But you dyno guys would have to return to the dyno every time you make a change to see what it did and i doubt if that happens unless it's your profession.A life long local racer who has raced everything from small blocks to Hemis had little use for a dyno and in his book he wrote the highest horsepower engines never et'd well. Always made his changes based on the total package,logic and experience... then went the track.
j par
Well-hung Member
Until yellow rose forgets to take his meds..
How long will this thread stay on the rails... LOL..
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How long will this thread stay on the rails... LOL..
..
33IMP
Well-Known Member
GER. Worst. Converter. EVER!
justinp61
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Using speed it's down 31hp, ET it's down 51hp. I'm not sure how much loss there is driving the water pump, fan and alternator, plus header and ignition differences.
Yep, they're not the lone ranger either... plenty of other sources out there masquerading as 'quality' pieces. Although, not as bad as it used to be.
Some guys can’t track tune a car let alone an engine. For those guys Dyno operators are a blessing and can get your engine safely fired up for you and broken in. To bad they don’t follow you to the track to finish the job but then again they may not be able to do that either. As for the excuse I use the Dyno for finding leaks that doesn’t always work either does it.
ir3333
Well-Known Member
a small block that dynode 400...
at 6000 rpm the fan, water pump, fuel pump, alternator, air cleaner and full exhaust might be 40 hp.
If the dyno is out 10% of 400 that's another 40 hp....now that 400 hp small block might be 320 at the crank and 240 at the rear wheels.
a recent news report said 6% of all accidents are caused by alcohol.That means 94% of the accidents were caused by people who weren't drinking!
You can read the numbers how you like.
It takes me quite awhile to completely tune and get the bugs out of a new build, maybe a few weeks of different driving and weather but i am very fussy.Never been on a dyno...maybe i should?
at 6000 rpm the fan, water pump, fuel pump, alternator, air cleaner and full exhaust might be 40 hp.
If the dyno is out 10% of 400 that's another 40 hp....now that 400 hp small block might be 320 at the crank and 240 at the rear wheels.
a recent news report said 6% of all accidents are caused by alcohol.That means 94% of the accidents were caused by people who weren't drinking!
You can read the numbers how you like.
It takes me quite awhile to completely tune and get the bugs out of a new build, maybe a few weeks of different driving and weather but i am very fussy.Never been on a dyno...maybe i should?
ir3333
Well-Known Member
It's hard to imagine someone in this hobby that builds and or races these cars that can't tune one.
Heck guys won’t even invest in a 300.00 weather station and without weather conditions how can you tell if what you did helped or hurt.
66 Dart 273 hipo
Well-Known Member
Hey guys just read one of those early 70’s mopar books. Pretty must explains everything in real laymen’s terms. But don’t blame me when you see your hp numbers. Lol
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