C30A underrated??

Brian2by2 · 18 November 2003

I've read the FAQ's board before, but today, I stumbled upon this and wondered if the C30A is underrated...

My 1991 car, number 601, was an early model. Power at the rear wheels (stock) was 249 hp at just under 7500 rpm. My chassis dyno guy recommends a conversion factor of 1.26 x wheel hp to get engine, resulting in 313 hp. And remember Honda rated the engine at 270 hp. Losses are actually probably less because the power train does not need to bend the power through 90 degrees, the NSX is a side winder...so power is probably even greater.

I have run cars that have a power/weight advantage over 270hp, but no 313....makes sense...guess i'm gonna have to dyno it.

The only explanation I have is 1.26 x RWHP isn't accurate on an MR car because the drive-train lose is so much less than on front mounts.....

Ojas · 18 November 2003

Brian2by2 said:
The only explanation I have is 1.26 x RWHP isn't accurate on an MR car because the drive-train lose is so much less than on front mounts.....

The 1.26 correction factor corresponds to a 20% drivetrain loss. As the excerpt suggests, that's probably too much. 12%-15% appears to be the commonly accepted figure for the NSX.

Brian2by2 · 18 November 2003

thanks

Arata · 18 November 2003

Power to weight ratio alone, does not determind how fast a car will accelerate. A big factor is how much weight is resiprocating weight, rotating weight, which will include rear wheel weight as well as rear discs.
This is what I call rate of acceleration. Why do you think Titanium rods are an advantage? Less weight. But the amount they change the Power to weight ratio is almost nothing.

Brian2by2 · 19 November 2003

Ya, I understand rotational mass and all that. I heard there are light weight rotors that are the same size as OEM...anyone have a link to a place that sells them?

Ojas · 19 November 2003

Arata said:
Power to weight ratio alone, does not determind how fast a car will accelerate. A big factor is how much weight is resiprocating weight, rotating weight, which will include rear wheel weight as well as rear discs.

Gearing, tractioning, and aerodynamics are factors as well, but aren't all the ones you mentioned already accounted for on a when measuring power on a conventional chassis dyno, hence already included in the power-to-weight figures?

Arata · 19 November 2003

Gearing, tractioning, and aerodynamics are factors as well, but aren't all the ones you mentioned already accounted for on a when measuring power on a conventional chassis dyno, hence already included in the power-to-weight figures?

not really, now we are talking about a maximum HP and using that to compare performance, But when we are talking about acceleration the max HP means very little. How quick you get there uses these other added parameters.

PorknBeanz · 19 November 2003

As far as light weight rotors... Still waiting for an update on these 14" Titanium rotors.

http://www.nsxprime.com/forums/showthread.php?s=&threadid=23456

Ojas · 19 November 2003

Arata said:
not really, now we are talking about a maximum HP and using that to compare performance, But when we are talking about acceleration the max HP means very little. How quick you get there uses these other added parameters.

You've answer a question I did not ask.

I did not make any claim to maximum power's importance or accuracy in determining acceleration.

Your original post stated "Power to weight ratio alone, does not determind how fast a car will accelerate. A big factor is how much weight is resiprocating..." The way I read it, it looked like "big factor" is something not already included in the "power" number. I was simply stating that measuring wheel power (at any RPM, not just at the one that gives you peak power) using a dyno (as Brian's first post mentioned), should already take these factors into account.

Sorry if I was less than clear.

Rubber Chicken · 19 November 2003

New S2000 is underrated by around 20 hp...

NetViper · 19 November 2003

Rubber Chicken said:
New S2000 is underrated by around 20 hp...

Then why is it NO faster at all in the 1/4 or trap speed than the old one?

NsSeX · 19 November 2003

it is faster. in v-tec temple they did comparison of the s22 and s2k and after first gear the s22 walked away from the s2k. i'll try and find the post. oh yeah they dynoed the s22 and it put down around 220-30 to the wheels. way underrated

C30A underrated??

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