Added AFR205, Ported TB, Results.
Originally Posted by samgm2
Either, I am confused or maybe everyone else is.
1. How can gearing rob you of power? Power is a measure of energy per unit time. Gearing doesn't matter at all - it is NOT involved in power calculations. The curve indicates the amount of power the engine generates at that RPM. Nothing more, nothing less. That question is rhetorical by the way. Gearing is irrelavent to the power on the curve.
2. In what way is the curve with the higher top end power better. Yes, this engine generates more power at the top end, but it lost a tremendous amount of power for everything UNDER 5500 rpm. This to me is not an advantage. Torque and HP took a huge beating at the RPMs he spends most of his time at.
3. More important that HP is the integral of power over the RPM range of interest. Another way of stating this? The AREA under the curve. Clearly the engine the makes more FINAL power has taken a REAL beating here and is outputting significantly less power throughout the RPM range.
It is unlikely that this engine would produce any better results at the track and perhaps worse without a pretty high Stall converter or a dramatically different gear ratios to put the engine in a much higher RPM range most of the time.
I am not trying to insite an argument here, but this seems to be a matter worthy of some discussion. He gained 30-40 HP on the top end and gave up as much as 125 HP at lower RPMs.
Sam
1. How can gearing rob you of power? Power is a measure of energy per unit time. Gearing doesn't matter at all - it is NOT involved in power calculations. The curve indicates the amount of power the engine generates at that RPM. Nothing more, nothing less. That question is rhetorical by the way. Gearing is irrelavent to the power on the curve.
2. In what way is the curve with the higher top end power better. Yes, this engine generates more power at the top end, but it lost a tremendous amount of power for everything UNDER 5500 rpm. This to me is not an advantage. Torque and HP took a huge beating at the RPMs he spends most of his time at.
3. More important that HP is the integral of power over the RPM range of interest. Another way of stating this? The AREA under the curve. Clearly the engine the makes more FINAL power has taken a REAL beating here and is outputting significantly less power throughout the RPM range.
It is unlikely that this engine would produce any better results at the track and perhaps worse without a pretty high Stall converter or a dramatically different gear ratios to put the engine in a much higher RPM range most of the time.
I am not trying to insite an argument here, but this seems to be a matter worthy of some discussion. He gained 30-40 HP on the top end and gave up as much as 125 HP at lower RPMs.
Sam
To answer your first question, you are confused...seriously.
1. How can gearing rob you power? It shows a loss on an inertia chassis dyno. Proven time and again. To describe how will take about 300 words. Better to just do a search.
2. You are obviously looking at the dyno sheets wrong. There are 4 graphs: 2 red graphs and 2 blue graphs. The blue graphs are the hp and torque curves of the old setup. The red graphs are the hp and tq curves of the setup with AFR heads. At no rpm level is the olds setup better in hp or torque. The AFR is better at every rpm level.
3. You are lost. You must think the torque graph is the old hp curve and the hp curve is the new hp curve. LOL. Compare the red (new) graphs to the blue (old) graphs and you will see the new setup trumps the old. He did not lose 125 hp. LMAO. You can remove the foot out of your mouth.
Thread Starter
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Originally Posted by Billiumss
Very impressive!!!!
Were those out of the box AFR heads?
How much more would you gain if you got them ported?
Were those out of the box AFR heads?
How much more would you gain if you got them ported?
Have no idea about porting them.
Steve
nice results, but I do question the loss of power due to gears? He didnt swap into a heavier rear did he? IF your swapping for factory gears here and not adding any weight to the drivetrain how to you loose power from the motor to the tires? I understand why you would by adding a a heavyduty rear-end, but how by a simple what 3:73? to 3:90 gear swap did he loose 8 rwhp? Looking for a good explanation, not trying to dis anyone.
Guys...
As Patrick G. so eloquently put it somewhere in his....uummmmm...reply, a lower gear set (that would be higher numerically of course) even in the exact same rear type, will always show less power on an inertia style chassis dyno due to the way it loads the dyno and also the increase in friction from the ring and pinion set-up that now has more teeth in contact per every single revolution it makes. The ring gear turns about 28 times per second at 135 MPH or so (with a 26" tall tire), so you can see why the additional tooth count will cost some power due to increased friction/drag per each revolution.
Barring not believing my brief explanation, do a search which was also suggested and you will see how many 390-410 gear swaps rob 7-10 RWHP on an inertia style chassis dyno...
Just my .02
Tony M.
As Patrick G. so eloquently put it somewhere in his....uummmmm...reply, a lower gear set (that would be higher numerically of course) even in the exact same rear type, will always show less power on an inertia style chassis dyno due to the way it loads the dyno and also the increase in friction from the ring and pinion set-up that now has more teeth in contact per every single revolution it makes. The ring gear turns about 28 times per second at 135 MPH or so (with a 26" tall tire), so you can see why the additional tooth count will cost some power due to increased friction/drag per each revolution.
Barring not believing my brief explanation, do a search which was also suggested and you will see how many 390-410 gear swaps rob 7-10 RWHP on an inertia style chassis dyno...
Just my .02
Tony M.
So from a 373 to 390 how many more teeth are there actualy? I'm having a hard time believing that a full 8rwhp loss from 373 to 390 and NO I cant find graphs of just such a change. I see plenty involving 12 bolts and 9" but thats not the same. I agree friction causes loss but that much for that little of a change seems kind of high. Not saying its impossible, just looking for the proof. He didnt go from 342's to 390's did he?
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Originally Posted by 99blancoSS
He didnt go from 342's to 390's did he?
Stated clearly in the very first post of this thread.
Again....Do a search on gear swaps and there effect on RWHP #'s....a wealth of information backing what we have touched on above.
Tony M.
I'v gone by a general rule of every 1/3 point increases losses by 1% (this would also be rpm dependent). Take with a grain of salt on this...it's just what I'v have seen before and after dynoing some combos.....
I will tell you that I lost 12 SAE rwhp going from a 10 bolt with 3.73's to a 12 bolt with 3.73's....
I will tell you that I lost 12 SAE rwhp going from a 10 bolt with 3.73's to a 12 bolt with 3.73's....