Rear Wheel HP results - Page 5

Iron Sheik · 06-01-04, 05:29 PM

My GT will be drag raced, broken transaxel, broken engine, broken what ever. [img]/ubbthreads/images/graemlins/grin.gif[/img]

Infact, I am buying a new motor from BAD-ASS racing in Sonoma this week. Rick Mertz is my hero (even though I know nothing about him) [img]/ubbthreads/images/graemlins/crazy.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

He has done it, it can be done,,,,,IMHO of course!

JP · 06-01-04, 05:33 PM

Howard,

Nice post! That's a nice list of things to do that I will impliment. I really think this will be the year for sub 12sec runs here in the U.K. Practice, pratice and more practice - and a few drive shafts!! [img]/ubbthreads/images/graemlins/grin.gif[/img]

JP · 06-01-04, 05:38 PM

[ QUOTE ]
He has done it, it can be done,,,,,IMHO of course!

[/ QUOTE ]

EXACTLY! [img]/ubbthreads/images/graemlins/cool.gif[/img] [img]/ubbthreads/images/graemlins/cool.gif[/img]

Ron Earp · 06-01-04, 06:34 PM

Don't really see why we should see exploding Porsche G50/50s. There are more than a few Porsche 911 turbos running <12s and they don't explode daily.

Still, < 1.5 60ft times scare me with a transaxle. Hell, they scare me with a 9" Ford and built C4, and for good reason - plenty of those have grenaded and are much stronger.

R

Malcolm · 06-02-04, 09:02 AM

I do not disagree with the kind of settings mentioned above, in fact I used to do some of them myself some years ago. A gardener contact was into drag racing and had made similar suggestions! However Brighton is a one off event each year. One of about 10 events, with the others all having corners! Therefore our cars are compromised as every other event would require different settings and not everyone is prepared to make the changes from venue to venue. With the advice above, maybe some will try it out and see what happens. Should be good whatever!

JP · 06-02-04, 09:07 AM

Yeah but Malc I've got more time on my hands or should I say lack of childern!! [img]/ubbthreads/images/graemlins/grin.gif[/img]

Mark Worthington · 06-02-04, 09:11 AM

With all the talk about drag racing I thought I'd elaborate a bit about my philosophy regarding GT40s and the 1320. First, a GT40 is NOT a drag car; it was designed to go fast around the LeMans circuit. Second, drag racing IS fun. While it would be nice to knock off an 11-second timeslip, I think it would be even more fun to end up with a trap speed of ~132 mph. I would really enjoy passing a 12-second Camaro or Corvette at the 1,000-foot mark with a closing speed of 25 mph.

gt40rick · 06-02-04, 10:24 AM

The most important thing to getting as good of a run as possible with any car is to get the launch right any wheel spin will eat up your ET. I believe that if a GT40 has 375 to 400hp at the wheels and your launch is good your car will run 11.7 with wide street tires, a little better with sticky rubber. I have run my GT40 many times down the 1/4 mile with times from 11.478 to 12. 426. I would like to add that my G50 shows no signs of wear I have drained and replaced the oil every winter and it has always looked like brand new. I have broken axles and CV joints BEFORE I found a setup that works. My current axles and CV joints have had about 20 runs down the 1/4 mi without any problems. I agree that the GT40 is not a drag car but I also believe that any well engineered car should be able to be drag raced, road raced, auto crossed or driven to work and not have any problems. I am sure that if you are able to get a new Ford GT you will be able to run it on the drag strip, racetrack or the city streets and not break anything for a very long time because the car was designed to be an all around performance car.

gt40rick · 06-02-04, 10:31 AM

I almost forgot the best part about the guys with a 11 sec street car is that they can not go over 175mph because their gearing is too low (they use gearing as much as HP)... but a lot of us can... if we want to. [img]/ubbthreads/images/graemlins/grin.gif[/img]

Hershal Byrd · 06-02-04, 10:55 AM

I watched Rick at the tree and I still think his launches were still a little on the safe side. I really think his times could have been a little quicker.

Hersh [img]/ubbthreads/images/graemlins/smile.gif[/img]

Hershal Byrd · 06-02-04, 11:01 AM

I forgot to mention that I think shift lag is probably the biggest time eater for a gt40 in the quatrer mile. The linkage on most GT's are not for speed shifting. I bet one with a paddle shifter would be considerably faster than another with a standard shifter.

Hersh [img]/ubbthreads/images/graemlins/smile.gif[/img]

Kevin M · 06-06-04, 08:28 PM

Ron,

There is a known friction loss between all gears under load (This is why most high power race cars have trans coolers). Fairly low when the power is being transmitted in a straight line and considerably higher when it has to make a 90deg. turn (Differential). This loss is directly proportional to the load and so varies as a percentage of the torque. There are also issues of the type of gear teeth. Straight cut teeth have less frictional loss (Hence their use in racing boxes and Ferraris), but they make a great deal of noise.

There are also drag losses from seals, which vary with RPM but not load, and bearings which vary with RPM and could vary with load if the design of the cluster is such that the bearings see a greater load with increased torque.

I used to know how to calculate this stuff, but haven’t done it in years and really don’t remember anymore. If we could get Adam to jump in on this I’m sure he could give you the formulas.

Kevin

Gary Gibbs · 06-07-04, 09:20 PM

Under these asumptions (and since HP is torque times RPM) the loss would be a percentage of HP also?

Iron Sheik · 06-07-04, 10:19 PM

So, if you have a 200hp motor in a GT40 and say you loose 30% of HP loss due to drive train, it would be 60hp loss.

AND THEN, if you have 1000hp motor in the same exact car, you loose 300hp?!!!! [img]/ubbthreads/images/graemlins/crazy.gif[/img] [img]/ubbthreads/images/graemlins/confused.gif[/img] [img]/ubbthreads/images/graemlins/crazy.gif[/img]

This makes no sense to me!

Mark Worthington · 06-07-04, 10:55 PM

Drivetrain losses are both inertial and frictional. Inertial losses, such as the energy required to accelerate a given flywheel or gears inside a transaxle or rear tires (for a chassis dyno) are fixed and are independant of engine output. Frictional losses will increase with torque. Everything I've read indicates that the inertial losses will dominate the frictional losses.

Ron Earp · 06-27-04, 09:38 PM

ttt

roaldin · 07-09-04, 06:28 AM

[ QUOTE ]
Ron,

Re:- "static" vs "percentage" drivetrain losses.

A reasonably well known Sydney performance identity has played around with this.
He claims that there is both a "static loss" and a "percentage loss".
Unfortunately there seem to be too many variables to come up with a rule of thumb.
If I can find his discussion I'll post it.

[/ QUOTE ]

Unfortunately, try as I might I can't locate it. The general thrust was that he'd done some tests with a few cars/engines and determined that losses varied but only to a reasonably small degree within a fairly wide range of engine output for each engine/vehicle combination. Therefore the "static loss" plays a bigger part than "percentage loss".

Tim.