How do you rolling road remap and auto?
Discussion
Say you built an engine with higher compression and higher lift cam that was to be fitted into a car with an auto transmission.
You want to remap the ECU on a rolling road.
Can you do this?
I think the dyno results would be nonsense because of the torque converter losses?
Or do you have to use an engine dyno?
You want to remap the ECU on a rolling road.
Can you do this?
I think the dyno results would be nonsense because of the torque converter losses?
Or do you have to use an engine dyno?
I don't have an answer to how you would rolling road an auto but have had my auto on a rolling road and can confirm that the figures that I got on the print out were more than useless!
The torque figures were sky high for some reason but the BHP figures were way down on what I thought and had been told they would be.
I would expect the engine dyno would be the best option for true figures but will try and contact the tunning company that did my car and see if he can answer the question.
The torque figures were sky high for some reason but the BHP figures were way down on what I thought and had been told they would be.
I would expect the engine dyno would be the best option for true figures but will try and contact the tunning company that did my car and see if he can answer the question.
P10DGR said:
I don't have an answer to how you would rolling road an auto but have had my auto on a rolling road and can confirm that the figures that I got on the print out were more than useless!
The torque figures were sky high for some reason but the BHP figures were way down on what I thought and had been told they would be.
That's pretty much par for the course in my experience.The torque figures were sky high for some reason but the BHP figures were way down on what I thought and had been told they would be.
Huntsman said:
Say you built an engine with higher compression and higher lift cam that was to be fitted into a car with an auto transmission.
You want to remap the ECU on a rolling road.
Can you do this?
I think the dyno results would be nonsense because of the torque converter losses?
Or do you have to use an engine dyno?
A dyno is a tool not a measure. So in terms of tuning it is fine. In terms of power readings, well they can all be a bit flaky and woolly anyhow so don't worry.You want to remap the ECU on a rolling road.
Can you do this?
I think the dyno results would be nonsense because of the torque converter losses?
Or do you have to use an engine dyno?
That said, it'll work just the same.
HP = torque x rpm / 5252
Being an auto won't change this. If you have a lot of power and a huge aftermarket stall you can get some funky numbers, but if it's all quite stock then I don't see an issue at all.
BTW - if it's tuning you want, try and find a RR which is an eddy current load bearing dyno. Much better for tuning IMO.
P10DGR said:
I don't have an answer to how you would rolling road an auto but have had my auto on a rolling road and can confirm that the figures that I got on the print out were more than useless!
The torque figures were sky high for some reason but the BHP figures were way down on what I thought and had been told they would be.
I would expect the engine dyno would be the best option for true figures but will try and contact the tunning company that did my car and see if he can answer the question.
This all depends on the dyno and operator.The torque figures were sky high for some reason but the BHP figures were way down on what I thought and had been told they would be.
I would expect the engine dyno would be the best option for true figures but will try and contact the tunning company that did my car and see if he can answer the question.
Remember dyno's don't measure HP, they measure torque and then calculate HP, as automotive Bhp is a derived (calculated number).
So HP = torque x rpm / 5252
Depending on what feed the operator was using for the rpm value will affect the results. As in they might be using roller rpm or engine rpm.
Gear selection can affect this, i.e. if they use 1st gear and roller rpm, the the rpm will be lot lower than using 3rd gear. This means you'll see more torque, but less HP.
Non lock up converters can cause false readings too.
And a lot of auto's don't allow full power in 1st gear and have torque restrictions on the engine.
My auto Camaro went on a dyno the other year. In 1st gear it produced lower results. I questioned the operator who begrudging agreed to re-run it using a higher gear. It made 40rwhp more!!!
Final figures where 358hp (flywheel). However I think this is a bit high, and if you look at the graph there is a torque spike from the converter when it shifted gears. If you profile the graph it reads a PEAK of 320hp (flywheel) which is about bang on what these should make.
300bhp/ton said:
This all depends on the dyno and operator.
Remember dyno's don't measure HP, they measure torque and then calculate HP, as automotive Bhp is a derived (calculated number).
So HP = torque x rpm / 5252
Depending on what feed the operator was using for the rpm value will affect the results. As in they might be using roller rpm or engine rpm.
Gear selection can affect this, i.e. if they use 1st gear and roller rpm, the the rpm will be lot lower than using 3rd gear. This means you'll see more torque, but less HP.
Non lock up converters can cause false readings too.
And a lot of auto's don't allow full power in 1st gear and have torque restrictions on the engine.
My auto Camaro went on a dyno the other year. In 1st gear it produced lower results. I questioned the operator who begrudging agreed to re-run it using a higher gear. It made 40rwhp more!!!
Final figures where 358hp (flywheel). However I think this is a bit high, and if you look at the graph there is a torque spike from the converter when it shifted gears. If you profile the graph it reads a PEAK of 320hp (flywheel) which is about bang on what these should make.
So in summary a rolling road dyno can be used to support remapping an ECU on a modified engine with an autobox.Remember dyno's don't measure HP, they measure torque and then calculate HP, as automotive Bhp is a derived (calculated number).
So HP = torque x rpm / 5252
Depending on what feed the operator was using for the rpm value will affect the results. As in they might be using roller rpm or engine rpm.
Gear selection can affect this, i.e. if they use 1st gear and roller rpm, the the rpm will be lot lower than using 3rd gear. This means you'll see more torque, but less HP.
Non lock up converters can cause false readings too.
And a lot of auto's don't allow full power in 1st gear and have torque restrictions on the engine.
My auto Camaro went on a dyno the other year. In 1st gear it produced lower results. I questioned the operator who begrudging agreed to re-run it using a higher gear. It made 40rwhp more!!!
Final figures where 358hp (flywheel). However I think this is a bit high, and if you look at the graph there is a torque spike from the converter when it shifted gears. If you profile the graph it reads a PEAK of 320hp (flywheel) which is about bang on what these should make.
Why on earth would you try and get a dyno figure in first gear? 
To get a realistic number, you need to be in whatever gear gives you a 1 to 1 ratio and at a high enough RPM that the converter is locked up.
To answer the OP's question, you can quite happily dyno a car with an auto but whatever figure you get, this will be your Rear Wheel Horsepower or RHWP.
Some dyno operators do a funky coast down test which is supposed to calculate your transmission losses and give you a BHP figure but I wouldn't put too much faith in that.
The figures you achieve will almost certainly not correspond to anybody elses figures unless you both go to the same dyno on the same day and use the same correction figures.
To get a realistic number, you need to be in whatever gear gives you a 1 to 1 ratio and at a high enough RPM that the converter is locked up.
To answer the OP's question, you can quite happily dyno a car with an auto but whatever figure you get, this will be your Rear Wheel Horsepower or RHWP.
Some dyno operators do a funky coast down test which is supposed to calculate your transmission losses and give you a BHP figure but I wouldn't put too much faith in that.
The figures you achieve will almost certainly not correspond to anybody elses figures unless you both go to the same dyno on the same day and use the same correction figures.
Huntsman said:
300bhp/ton said:
This all depends on the dyno and operator.
Remember dyno's don't measure HP, they measure torque and then calculate HP, as automotive Bhp is a derived (calculated number).
So HP = torque x rpm / 5252
Depending on what feed the operator was using for the rpm value will affect the results. As in they might be using roller rpm or engine rpm.
Gear selection can affect this, i.e. if they use 1st gear and roller rpm, the the rpm will be lot lower than using 3rd gear. This means you'll see more torque, but less HP.
Non lock up converters can cause false readings too.
And a lot of auto's don't allow full power in 1st gear and have torque restrictions on the engine.
My auto Camaro went on a dyno the other year. In 1st gear it produced lower results. I questioned the operator who begrudging agreed to re-run it using a higher gear. It made 40rwhp more!!!
Final figures where 358hp (flywheel). However I think this is a bit high, and if you look at the graph there is a torque spike from the converter when it shifted gears. If you profile the graph it reads a PEAK of 320hp (flywheel) which is about bang on what these should make.
So in summary a rolling road dyno can be used to support remapping an ECU on a modified engine with an autobox.Remember dyno's don't measure HP, they measure torque and then calculate HP, as automotive Bhp is a derived (calculated number).
So HP = torque x rpm / 5252
Depending on what feed the operator was using for the rpm value will affect the results. As in they might be using roller rpm or engine rpm.
Gear selection can affect this, i.e. if they use 1st gear and roller rpm, the the rpm will be lot lower than using 3rd gear. This means you'll see more torque, but less HP.
Non lock up converters can cause false readings too.
And a lot of auto's don't allow full power in 1st gear and have torque restrictions on the engine.
My auto Camaro went on a dyno the other year. In 1st gear it produced lower results. I questioned the operator who begrudging agreed to re-run it using a higher gear. It made 40rwhp more!!!
Final figures where 358hp (flywheel). However I think this is a bit high, and if you look at the graph there is a torque spike from the converter when it shifted gears. If you profile the graph it reads a PEAK of 320hp (flywheel) which is about bang on what these should make.
Huntsman said:
300bhp/ton said:
This all depends on the dyno and operator.
Remember dyno's don't measure HP, they measure torque and then calculate HP, as automotive Bhp is a derived (calculated number).
So HP = torque x rpm / 5252
Depending on what feed the operator was using for the rpm value will affect the results. As in they might be using roller rpm or engine rpm.
Gear selection can affect this, i.e. if they use 1st gear and roller rpm, the the rpm will be lot lower than using 3rd gear. This means you'll see more torque, but less HP.
Non lock up converters can cause false readings too.
And a lot of auto's don't allow full power in 1st gear and have torque restrictions on the engine.
My auto Camaro went on a dyno the other year. In 1st gear it produced lower results. I questioned the operator who begrudging agreed to re-run it using a higher gear. It made 40rwhp more!!!
Final figures where 358hp (flywheel). However I think this is a bit high, and if you look at the graph there is a torque spike from the converter when it shifted gears. If you profile the graph it reads a PEAK of 320hp (flywheel) which is about bang on what these should make.
So in summary a rolling road dyno can be used to support remapping an ECU on a modified engine with an autobox.Remember dyno's don't measure HP, they measure torque and then calculate HP, as automotive Bhp is a derived (calculated number).
So HP = torque x rpm / 5252
Depending on what feed the operator was using for the rpm value will affect the results. As in they might be using roller rpm or engine rpm.
Gear selection can affect this, i.e. if they use 1st gear and roller rpm, the the rpm will be lot lower than using 3rd gear. This means you'll see more torque, but less HP.
Non lock up converters can cause false readings too.
And a lot of auto's don't allow full power in 1st gear and have torque restrictions on the engine.
My auto Camaro went on a dyno the other year. In 1st gear it produced lower results. I questioned the operator who begrudging agreed to re-run it using a higher gear. It made 40rwhp more!!!
Final figures where 358hp (flywheel). However I think this is a bit high, and if you look at the graph there is a torque spike from the converter when it shifted gears. If you profile the graph it reads a PEAK of 320hp (flywheel) which is about bang on what these should make.
mrmr96 said:
Yes. Don't forget you can remap a car on the road - so the figures produced by the dyno (power/torque) are of limited relevance. When you're remapping a car you're trying to turn the boost up to a sensible limit, and configure the boost controller to have it hold where you want it to. Then you're leaning the fuel out to get the perfect AFR, and you're advancing the ignition as far as you can before it knocks. Boost is measured by a boost gauge. AFR is measured using an exhaust probe. Det is measured with cans, or knock count on the ECU. There's no need for a dyno. The dyno is generally used after tuning to work out the power gain. Some people will map on a dyno because it can be used to control conditions better, like speed and load etc. This enables more accurate mapping of the areas where you're not on full load (full throttle) to manage the feel as you feed in more power etc. It's not always as good as mapping on the road though, especially for turbo cars which generate boost differently to on the dyno due to the rate at which the revs rise affecting the spool.
The case I had in mind isnt a turbo, but useful info thanks.
HD Adam said:
To get a realistic number, you need to be in whatever gear gives you a 1 to 1 ratio and at a high enough RPM that the converter is locked up.
To answer the OP's question, you can quite happily dyno a car with an auto
So now all you've got to work out is how you're going to get the auto to stay in that gear at full throttle....To answer the OP's question, you can quite happily dyno a car with an auto
It ain't going to. It's going to kick down to a lower gear. Which is what auto's do. Which is why the engines in auto cars last longer than in manual cars. The auto transmission protects the engine from idiot drivers. And from dyno tests.
Ozzie Osmond said:
HD Adam said:
To get a realistic number, you need to be in whatever gear gives you a 1 to 1 ratio and at a high enough RPM that the converter is locked up.
To answer the OP's question, you can quite happily dyno a car with an auto
So now all you've got to work out is how you're going to get the auto to stay in that gear at full throttle....To answer the OP's question, you can quite happily dyno a car with an auto
It ain't going to. It's going to kick down to a lower gear. Which is what auto's do. Which is why the engines in auto cars last longer than in manual cars. The auto transmission protects the engine from idiot drivers. And from dyno tests.
Now idea what you mean about lasts longer....
As for dyno's, just start in 1st and floor it, let it change up and keep the dyno recording....
Ozzie Osmond said:
HD Adam said:
To get a realistic number, you need to be in whatever gear gives you a 1 to 1 ratio and at a high enough RPM that the converter is locked up.
To answer the OP's question, you can quite happily dyno a car with an auto
So now all you've got to work out is how you're going to get the auto to stay in that gear at full throttle....To answer the OP's question, you can quite happily dyno a car with an auto
It ain't going to. It's going to kick down to a lower gear. Which is what auto's do. Which is why the engines in auto cars last longer than in manual cars. The auto transmission protects the engine from idiot drivers. And from dyno tests.
Auto engines last longer because the transmission takes out any shock loading coming back through the drive train, nothing to do with idiot drivers. You can still pre select a gear and rev to the limiter in older slush-box autos.
Edited by busta on Monday 8th November 15:39
Ozzie Osmond said:
So now all you've got to work out is how you're going to get the auto to stay in that gear at full throttle....
In the 928, it'll hold the manually selected gear unless the RPM drops below about 1500rpm, or you hit the electronic kickdown switch right on the end of the throttle travel. The box and its control system are ancient.Hitting the kickdown switch can be entertaining (my car started cresting the rollers when Vixpy tested it), but it's not rocket science to disconnect it so the throttle can be mashed without fear of cars launching across booths.
On newer stuff with tip/selectronic style manual selection systems it's pretty much the same, probably even better if it'll hold the gear from tickover.
Ozzie Osmond said:
HD Adam said:
To get a realistic number, you need to be in whatever gear gives you a 1 to 1 ratio and at a high enough RPM that the converter is locked up.
To answer the OP's question, you can quite happily dyno a car with an auto
So now all you've got to work out is how you're going to get the auto to stay in that gear at full throttle....To answer the OP's question, you can quite happily dyno a car with an auto
It ain't going to. It's going to kick down to a lower gear. Which is what auto's do. Which is why the engines in auto cars last longer than in manual cars. The auto transmission protects the engine from idiot drivers. And from dyno tests.
On my idiot proof automatic, if you conduct the test with the gear selector in "3" and over 3200rpm, the converter is locked and it will not kick down.
If I want to get really sexy, my tuning software allows me the option of locking the gearbox in 3rd gear (1:1 ratio) just in case I manage to screw up and let the rpm start below 3200rpm.
I believe that the OP was looking for answers, not opinions or guesswork.
HD Adam said:
Ozzie Osmond said:
HD Adam said:
To get a realistic number, you need to be in whatever gear gives you a 1 to 1 ratio and at a high enough RPM that the converter is locked up.
To answer the OP's question, you can quite happily dyno a car with an auto
So now all you've got to work out is how you're going to get the auto to stay in that gear at full throttle....To answer the OP's question, you can quite happily dyno a car with an auto
It ain't going to. It's going to kick down to a lower gear. Which is what auto's do. Which is why the engines in auto cars last longer than in manual cars. The auto transmission protects the engine from idiot drivers. And from dyno tests.
On my idiot proof automatic, if you conduct the test with the gear selector in "3" and over 3200rpm, the converter is locked and it will not kick down.
If I want to get really sexy, my tuning software allows me the option of locking the gearbox in 3rd gear (1:1 ratio) just in case I manage to screw up and let the rpm start below 3200rpm.
I believe that the OP was looking for answers, not opinions or guesswork.
When one of the Se7ens owners took his drag-racer Westfield to Emerald for a RR session, Dave Walker did his best to get a reading but the kick-down was almost unmanageable, and led to a few hairy moments. You really need to be performing your testing in one gear, preferably a high gear (assuming the rollers can cater for the road speed) to limit the torque the wheels make which can lead to the car climbing off the rollers (even if it is strapped down). Dave mentioned then that he'd prefer never to test an auto again.
Modern autos can be forced to remain in one gear. My Scooby allows me to "tip" it into gear and hold it there but if I really start to push-on, it overrides me and changes up anyway. Idiot proof, yes, but not so useful in this scenario.
Modern autos can be forced to remain in one gear. My Scooby allows me to "tip" it into gear and hold it there but if I really start to push-on, it overrides me and changes up anyway. Idiot proof, yes, but not so useful in this scenario.
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