Laguna Updates?
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From: Anaheim, Orange County
Originally Posted by ole p car,Oct 7 2008, 10:44 AM
Oh now you want to hear from the "Relic, lipstick wearing pig"??
Yeah, its funny what a little bit of hp buys you. my extra 60hp was worth about a second as planned. Now, i need some brakes to match.
I did a side by side video comparison of the laps at the last laguna and our dry race on sunday. I shift a little earlier, but the slower version of my car goes deeper in the brakes and makes up for a lot of the power. pretty interesting. in the end, only fractions of seconds faster per corner.
Thunderhill will be interesting, but Ryal has always been faster there anyway, or equal when our hp to weights were near equal a couple of years ago.
165 at t-hill? is that was data aqu. is telling you ?? im probably not going to be much more than i was at laguna or in otherwords, 125-130ish.
Its not SAE, but i do use the generally accepted gross estimation of flywheel hp by taking rear wheel divided by .85. (15% drive train loss)
Dont get me started on the torque thing.
Anyway, it was some fun racing. Even that rain race was a great time! (although it would have been nicer to be on rains like Rylan rather than the SLICKs i was on!!)
mk
Yeah, its funny what a little bit of hp buys you. my extra 60hp was worth about a second as planned. Now, i need some brakes to match.
I did a side by side video comparison of the laps at the last laguna and our dry race on sunday. I shift a little earlier, but the slower version of my car goes deeper in the brakes and makes up for a lot of the power. pretty interesting. in the end, only fractions of seconds faster per corner.
Thunderhill will be interesting, but Ryal has always been faster there anyway, or equal when our hp to weights were near equal a couple of years ago.
165 at t-hill? is that was data aqu. is telling you ?? im probably not going to be much more than i was at laguna or in otherwords, 125-130ish.
Its not SAE, but i do use the generally accepted gross estimation of flywheel hp by taking rear wheel divided by .85. (15% drive train loss)
Dont get me started on the torque thing.
Anyway, it was some fun racing. Even that rain race was a great time! (although it would have been nicer to be on rains like Rylan rather than the SLICKs i was on!!)
mk
Dynapack HP numbers are close to crank HP.
Mustang and Dyno dynamics are ~20-25% less.
Dynojet is somewhere in between.
There are ways to make the numbers look skewed either way also, but the delta is what is important when considering gains from modifications...
165MPH is possible, but not in THAT car at THAT track
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From: Concord, CA
Originally Posted by Asura,Oct 8 2008, 07:36 PM
How is the J's Racing car treating you?
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I guess we are getting caught up in the factors and types of dynos.
Becasue you are testing rear axle values, whether it be a brake dyno (or eddy current dyno), the only think you are going to be reducing the theoretical number by, is the rolling friction. because ive measured it several times, you might be able to just quote me on it. In neutral, at 150mph to 100mph its near 20hp and down at 80mph and slower its 10 hp or less. thats a constant that is only relative to the rolling friction x speed. Its going to be true for any car strapped down to the dyno with the same force and with the same tires and pressures.
Now, mustang dyno (eddy current dyno) vs dynopack (brake dyno?) they are measuring force that is required to keep a constant speed at a specific, "known" friction or force . if they are calibrated correctly, they should be the same. there is no reason why they would be different. a chassis dyno is measuring the rate of change of acceleration, or a rate of change of kinetic energy. newtonian physics, 101. (maybe 201). you have a known drum size and weight and you accelerate it with your rear tires. faster it accelerates, the more HP. very accurate. the only real variable, is tire slip.(not common) and SAE vs actual conversions. I always try and do my dyno in the summer or winter when the temps are near SAE conditions so there is little conversion.
So, its unheard of that you can go through a multistage gear system and have only 10% loss. generally, its more like 14-17% loss. not to mention, you also have a diff (another gear reduction) to go through. (kind of counted in the 14-17% loss). 390rwhp will be around 460flywheel HP. I would bet dollars to donuts that if you put Ry's 390rwhp monster on the engine dyno it would be near 460hp. the forces on the engine are more due to it driving a blower, which must be an extra 20-30hp acting on the engine components to get 390rwhp.
You mention Jerry Woods. No, Ive never done anything with them except race against their $60k cars , which are works of art! But, ive seen a few of their engine dyno results and seen those cars on the chassis dyno and it verified the 15% 1oss. It was more like 13% if i remember, but their transmissions are pretty efficient. The vipers are another that only show a 11% loss. I dont know if the S2000 has that kind of gear box, but the coversion from a dynojet, to a mustang dyno to the dynopac (which i thought was a mustang dyno) shouldnt be that much.
I dont know often you have done both, but my car was running within a few hp every single year and was tested a min of 2 times a year for 7 years. when i did the dyno.( I think it was the dynopac) the hp output was about 3hp less than my usual dyno runs. anyway, if the dynopac measures a hp and a torque at a specific speed, it should be easily replicated on the dynojet, minus the rolling friction i mentioned earlier.
You said
Our Dynapack numbers are within 10% of FWHP. Add 10% to the 390HP on the Dynapack and that is the high side of what we are making at the Flywheel as stated previously.
You cant take 390hp and ad 10% and get back your 10% loss. simple math mistake there. You need to divide 390 by .90 and that will get your flywheel HP.
(eg: 390 x 1.10 = 429 and 390 x / .90 = 433 and it gets worse at the larger loss percentages. with a 15% loss, flyweel hp would be 458, while 1.15x 390 =448. There is 2% off the problem right there). Also, the 928 comparison with a 20% loss would be 331flywheelHP not 318 as you mentioned for a 5% mistake. (same math conversion issue). (Rylan's 400hp at 10% loss would be 444rwhp, not 440. so, if you use 15% loss, 400rwhp is 460fwhp)
So, the point is............I just havent seen that much difference between dynos and vs an engine dyno, drivetrain losses seem to be in the 15% range and no more unless you have an automatic. I also agree. some cars run right at their rated hp , but have been underrated by the factory. some porsches are like this.
mine is not. its common to find S4 928s with 275rwhp, which is near 320+hp a little over the factory ratings. however, no way that it could ever be flywheel rated near 345hp if you used a 20% loss. the GTS and its bigger 5.4 liter engine, was rated at 345rwhp and it is commonly rear wheel dynoed at 295rwhp.
end of my dyno ramblings. You are also right, its all relative. AND, i also agree that for tuning , in some ways the brake dynos can be better. But, many have found tuning on a dynojet to be quite rewarding due to the actual speed ramp times, and ECU response times, being close to racing conditions.
Becasue you are testing rear axle values, whether it be a brake dyno (or eddy current dyno), the only think you are going to be reducing the theoretical number by, is the rolling friction. because ive measured it several times, you might be able to just quote me on it. In neutral, at 150mph to 100mph its near 20hp and down at 80mph and slower its 10 hp or less. thats a constant that is only relative to the rolling friction x speed. Its going to be true for any car strapped down to the dyno with the same force and with the same tires and pressures.
Now, mustang dyno (eddy current dyno) vs dynopack (brake dyno?) they are measuring force that is required to keep a constant speed at a specific, "known" friction or force . if they are calibrated correctly, they should be the same. there is no reason why they would be different. a chassis dyno is measuring the rate of change of acceleration, or a rate of change of kinetic energy. newtonian physics, 101. (maybe 201). you have a known drum size and weight and you accelerate it with your rear tires. faster it accelerates, the more HP. very accurate. the only real variable, is tire slip.(not common) and SAE vs actual conversions. I always try and do my dyno in the summer or winter when the temps are near SAE conditions so there is little conversion.
So, its unheard of that you can go through a multistage gear system and have only 10% loss. generally, its more like 14-17% loss. not to mention, you also have a diff (another gear reduction) to go through. (kind of counted in the 14-17% loss). 390rwhp will be around 460flywheel HP. I would bet dollars to donuts that if you put Ry's 390rwhp monster on the engine dyno it would be near 460hp. the forces on the engine are more due to it driving a blower, which must be an extra 20-30hp acting on the engine components to get 390rwhp.
You mention Jerry Woods. No, Ive never done anything with them except race against their $60k cars , which are works of art! But, ive seen a few of their engine dyno results and seen those cars on the chassis dyno and it verified the 15% 1oss. It was more like 13% if i remember, but their transmissions are pretty efficient. The vipers are another that only show a 11% loss. I dont know if the S2000 has that kind of gear box, but the coversion from a dynojet, to a mustang dyno to the dynopac (which i thought was a mustang dyno) shouldnt be that much.
I dont know often you have done both, but my car was running within a few hp every single year and was tested a min of 2 times a year for 7 years. when i did the dyno.( I think it was the dynopac) the hp output was about 3hp less than my usual dyno runs. anyway, if the dynopac measures a hp and a torque at a specific speed, it should be easily replicated on the dynojet, minus the rolling friction i mentioned earlier.
You said
Our Dynapack numbers are within 10% of FWHP. Add 10% to the 390HP on the Dynapack and that is the high side of what we are making at the Flywheel as stated previously.
You cant take 390hp and ad 10% and get back your 10% loss. simple math mistake there. You need to divide 390 by .90 and that will get your flywheel HP.
(eg: 390 x 1.10 = 429 and 390 x / .90 = 433 and it gets worse at the larger loss percentages. with a 15% loss, flyweel hp would be 458, while 1.15x 390 =448. There is 2% off the problem right there). Also, the 928 comparison with a 20% loss would be 331flywheelHP not 318 as you mentioned for a 5% mistake. (same math conversion issue). (Rylan's 400hp at 10% loss would be 444rwhp, not 440. so, if you use 15% loss, 400rwhp is 460fwhp)
So, the point is............I just havent seen that much difference between dynos and vs an engine dyno, drivetrain losses seem to be in the 15% range and no more unless you have an automatic. I also agree. some cars run right at their rated hp , but have been underrated by the factory. some porsches are like this.
mine is not. its common to find S4 928s with 275rwhp, which is near 320+hp a little over the factory ratings. however, no way that it could ever be flywheel rated near 345hp if you used a 20% loss. the GTS and its bigger 5.4 liter engine, was rated at 345rwhp and it is commonly rear wheel dynoed at 295rwhp.
end of my dyno ramblings. You are also right, its all relative. AND, i also agree that for tuning , in some ways the brake dynos can be better. But, many have found tuning on a dynojet to be quite rewarding due to the actual speed ramp times, and ECU response times, being close to racing conditions.
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Jerry Woods drives an Audi...go figure 
It seems we are quibbling over the little things that make the big differences. I think it's cool that the differences between our cars is consistently in the 1/100th of a second.
My only issue with the roller style dynos is the losses from tire inconsistencies (alignment, compounds, pressures). Tires also grow with increased speed. The Dynapack offers the ability to vary the ramp time. I use the same ramp time for all cars. Every car has to be checked off the dyno for transitional response and driveability. All our race cars idle like stock, and can be driven in traffic at low load with no issues either.
I built Bill's engine top to bottom and tuned it. I'll post a few pics of the insides. That should be the hot ticket next year
With 2 points lower compression, OEM honda header and a 70mm exhaust, Bill made 4% more power on the same dyno 407RWHP vs Ry's 393RWHP. Bill should be close to 460RWHP when all is said and done.
It seems we are quibbling over the little things that make the big differences. I think it's cool that the differences between our cars is consistently in the 1/100th of a second.
My only issue with the roller style dynos is the losses from tire inconsistencies (alignment, compounds, pressures). Tires also grow with increased speed. The Dynapack offers the ability to vary the ramp time. I use the same ramp time for all cars. Every car has to be checked off the dyno for transitional response and driveability. All our race cars idle like stock, and can be driven in traffic at low load with no issues either.
I built Bill's engine top to bottom and tuned it. I'll post a few pics of the insides. That should be the hot ticket next year
With 2 points lower compression, OEM honda header and a 70mm exhaust, Bill made 4% more power on the same dyno
407RWHP vs Ry's 393RWHP. Bill should be close to 460RWHP when all is said and done. 
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From: Concord, CA
Originally Posted by Asura,Oct 9 2008, 02:43 AM
I haven't seen you since the Time Attack, I trust all is well.
Hope you can make it to SP on Oct 31st
Hope you can make it to SP on Oct 31st