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Discussion Starter #1
Anyone know what the OEM stock RWHP rating is on a 2008 GT-500? I need to know this for a NASA road racing classification.

Secondly, what is the typical loss of HP at the rear wheels compared to engine HP? Is it 10%?

Thanks!
 

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Anyone know what the OEM stock RWHP rating is on a 2008 GT-500? I need to know this for a NASA road racing classification.

Secondly, what is the typical loss of HP at the rear wheels compared to engine HP? Is it 10%?

Thanks!
I would say between 10 and 15 percent. The stock rwhp for 07-09 is usually between upper 420's to upper 440's.
 

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I would say between 10 and 15 percent. The stock rwhp for 07-09 is usually between upper 420's to upper 440's.
Are those numbers based on pulls when the engine is cold or hot?

My 2008 dyno'd out at 412 rwhp after a 40 minute drive...so dyno'd when hot.
 

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Anyone know what the OEM stock RWHP rating is on a 2008 GT-500? I need to know this for a NASA road racing classification.

Secondly, what is the typical loss of HP at the rear wheels compared to engine HP? Is it 10%?

Thanks!
Loss on this car is right at 12%.

bj
 

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Discussion Starter #5
Thanks guys,

There's a good chance that I'll get my '08 with CAI, shorty headers and KR mufflers on the dyno this weekend at the NASA event at Summit Point. The RWHP ranges I've read are pretty wide depending on temperature and each engine's individual idiosyncracies, so it's anybody's guess. It'll be on a DynoJet which I hear is pretty consistent. I'll let you know in any event. Thanks for the info, though, it allows a preliminary clasification for the time being.
 

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Anyone know what the OEM stock RWHP rating is on a 2008 GT-500? I need to know this for a NASA road racing classification.

Secondly, what is the typical loss of HP at the rear wheels compared to engine HP? Is it 10%?

Thanks!
My stock 08 GT 500 put out 412 rwhp on a heat soaked engine and was dyno'd on a dynojet 248x. Temperatures with 83 F and humidity of 35%
 

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Discussion Starter #7
Thanks OD, that's great info to know as NASA requires the use of the DynoJet 248. So, thanaks to you I have a baseline stock number to work from. Thanks again!
 

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Thanks OD, that's great info to know as NASA requires the use of the DynoJet 248. So, thanaks to you I have a baseline stock number to work from. Thanks again!
FYI - I'm pretty sure my numbers might be a little low for these cars
 

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With a CAI from JLT, a computer tune from BrenSpeed (running the 'canned' 93 octane street tune -- plus an adjustment of 2 % on the AFR), and SLP loudmouths, on a 'mustang' dyno which is considered 'lower' than a dynojet... just last week...

pulled 540 RWHP! Was MOST PLEASED with these numbers.

This was 'cold'... let the car cool down in 73 deg outdoor temps for an hour after a 30 min drive to get to the shop... and with correction factors (temp/altitude)...

Did 4 pulls... and all were +/- 10 ... so have every confidence these were good numbers.


2008 GT500..

I think the sequential taillights might have added 2-3 HP :)
 

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It all depends on the model of Mustang Dynamometer that was used. I've had my car dynoed on a very stingy MD-600 model and my car came out with 474RWHP. My car is pullied and professionally tuned. My car was dynoed in stock form on the same machine and produced somewhere in the 380RWHP range. Compare that to people using other Mustang models or even Dynojet machines and there is quite a difference in numbers.

What is the standard? Who really knows.

Arbour88
 

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It all depends on the model of Mustang Dynamometer that was used. I've had my car dynoed on a very stingy MD-600 model and my car came out with 474RWHP. My car is pullied and professionally tuned. My car was dynoed in stock form on the same machine and produced somewhere in the 380RWHP range. Compare that to people using other Mustang models or even Dynojet machines and there is quite a difference in numbers.

What is the standard? Who really knows.

Arbour88
I recommend the cold air intake kit. It should give you at least 50 more rwhp...maybe even more. Of course you have to get it retuned.
 

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I recommend the cold air intake kit. It should give you at least 50 more rwhp...maybe even more. Of course you have to get it retuned.

I guess you didn't read my sig. I have Steeda cold air intake, Steeda pulley, Steeda tensioner, professional tune by our local Mustang tuning guru, Bassani catted 3" exhaust from the manifolds back including 'X' pipe. I'm at 3,300 feet elavation and with a Mustang MD-600 dyno the best my car could do was 474RWHP. My tuner says that this converts to roughly 540RWHP (give or take a few HPs, so not far from the RWHP numbers guys on this forum are reporting with similar mods) on a Dynojet machine. He knows his stuff. He is a well accomplished and reputed drag racer and a computer tuning whiz. His car (a 1990 coupe with 399 cubic inch naturallly aspirated engine with manual transmission) runs the 1/4 in 9.79 at 138.91 MPH (at a high elevation). His 1990 coupe weighs in at 3,200lbs and dynoed on his machine at 506RWHP. He also owns a 2007 magnum SRT8, a 2003 GT and a 2004 Kenne Bell powered Terminator. He has tuned many cars in the Calgary area. There is a reason why some guys will trailer their cars and make the 1,200kms drive (Winnipeg to Calgary) to have their cars tuned by him and only him.

All I'm saying in my post is that depending on the dyno machine you use, you will get different results (sometimes much more than you expect).

Arbour88
 

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I guess you didn't read my sig. I have Steeda cold air intake, Steeda pulley, Steeda tensioner, professional tune by our local Mustang tuning guru, Bassani catted 3" exhaust from the manifolds back including 'X' pipe. I'm at 3,300 feet elavation and with a Mustang MD-600 dyno the best my car could do was 474RWHP. My tuner says that this converts to roughly 540RWHP (give or take a few HPs, so not far from the RWHP numbers guys on this forum are reporting with similar mods) on a Dynojet machine. He knows his stuff. He is a well accomplished and reputed drag racer and a computer tuning whiz. His car (a 1990 coupe with 399 cubic inch naturallly aspirated engine with manual transmission) runs the 1/4 in 9.79 at 138.91 MPH (at a high elevation). His 1990 coupe weighs in at 3,200lbs and dynoed on his machine at 506RWHP. He also owns a 2007 magnum SRT8, a 2003 GT and a 2004 Kenne Bell powered Terminator. He has tuned many cars in the Calgary area. There is a reason why some guys will trailer their cars and make the 1,200kms drive (Winnipeg to Calgary) to have their cars tuned by him and only him.

All I'm saying in my post is that depending on the dyno machine you use, you will get different results (sometimes much more than you expect).

Arbour88

I spent several weeks in and around Calgary in the late 90's. Great town I thought, except it was too damned cold in January. Great skiing though.
 

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I spent several weeks in and around Calgary in the late 90's. Great town I thought, except it was too damned cold in January. Great skiing though.
I live here and all I can say is that you've got that right. That is why I bought a house is Arizona. :cheers:


Arbour88
 

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Arbour... found out it's a MD500
 

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When I was stock, 444/453 on a dynamometer. I need to go check now, but I want to finish mods and do a custom tune.
 
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