2L8IWON

I had a factory freak and dynoed BONE STOCK at 277rwhp and 299RWTQ

PlayMisty

I am going to have my bone stock manual 07 dynoed tomorrow morning. I'm not too optimistic as it's warm, the place is an hour's drive away, I'm at ca. 1000ft and the feds have welded an extra pair of mufflers in. I'll be very happy if I 'beat' my last car done at the same place; 267rwhp (an auto V8 sold as 320 flywheel hp, but old). Will let you know the results, for the stats.

AFBLUE

A point I want to make is that for some reason Ford dropped the HP # for the Shelby GT from 325 to 319. It's only 6hp, but I'm thinking that it must be right on the money. If they just wanted to be conservative and underate it they could have put 320 or 315.
Obviously I can't prove the above but, I think 319 is the no kidding flywheel hp for the Shelby GT. If it then dynos at 280 then the drivetrain loss is ~12%.

What is the flaw in my thinking (I'm not saying I'm right on this, but would like someone to provide a plausable alternative to why the Shelby advertised flywheel # is 319 and dyno is 280). From a marketing perspective there was no value gained by dropping the hp from what was originally promised. If anything it hurt the Shelby GT.

metroplex

The only way to find out is to plop the engine on an engine dyno and check the actual flywheel/crank power. Put that same engine into a S197 GT drivetrain and then run it on a chassis dyno. Remember to run it using 4th gear.

I have no idea why Ford chose to advertise as 319 hp and not 321 hp or 318 hp. Ford advertised the marauder as having a 302 hp 4.6L 4V V8. Why not stick with 300 hp, or 305 hp?

neil07gt

I hope I'm not stating the obvious but the Shelby GT has a FRPP CAI+tune, which is why it's rated at more power. right?

Knight

yes but thats not the event in question...its why ford rated it at 319hp then the 325 originaly stated.

Does FRPP CAI tune and axle back add up to 19hp increase?

metroplex

Since most CAIs add about 20-25 rwhp, Ford might have felt safer to underrate the horsepower.

PlayMisty

Results in: 279.66 PS (ca. 276hp) and 397.61 Nm torque (ca. 293 lb/ft)
23C, 962 Mbar, 26% humidity, uncorrected.

Bone stock 95RON fuel, has extra mufflers welded into pipes quite high up, power flattens right off after 5200, probably due to these. Dyno guy says 12% loss on manuals is about right nowadays. A/F good, a bit rich at the top end (5k +), maybe due to extra mufflers inhibiting airflow.

Next up, Diablo Predator with '93' tune (98RON) and K+N in stock airbox....

I have serious doubts about any CAI making 20hp on its own. With a tune and decent fuel, OK.

metroplex

The use of a CAI requires a tune due to the completely different air transfer function.

PlayMisty

Sure, slapping a CAI on isn't going to make 20hp alone. It's the tune that allows more fuel to be added to match any increased air supply. We both know this by the looks of it.

Funny to have the 12% figure reconfirmed by someone else who knows what they are doing though, isn't it? Looks like Ford's figure for the Mustang is a little conservative (but well within tolerances).

metroplex

As far as I can tell, no one has confirmed the 12%-12.2% figure. It's all guesstimation without doing any real testing. The "he said" or "he believes" statements is not confirmation without actual figures to back it up. Every platform is going to be different. The S197 is not the same as the previous generation of Mustang and isn't going to be the same as a Mercedes or Dodge.

One of the top tuners here at TMS said it was 16%. Tremec says the gearbox itself (not accounting for the rear suspension or drivetrain losses, which can be significant) is worth 2% in 4th gear (1:1 ratio). I'm not saying it can't be 12%. I am just saying that until someone actual does testing to confirm this 12% figure on the S197 GT, we can't be entirely sure.

metroplex

Most CAIs come with a flasher, and Shelby is going to tune the Shelby GTs before they leave the facility, so it is a moot point. The dyno results indicate 20-25 rwhp can be had from the use of a CAI (along with a tune).

Bullitt995

It also helps insurance rates to underrate the cars. Just look at the Ford GT, they claim 550 hp and it's normal for them to put down 550-560 rwhp.

metroplex

I wonder why they don't just severly underrate the cars? "Yeah the 2005-up Mustang GTs only make 260 hp like the 99-04..."

theedge67

That wouldn't sell as much. HP sells.

jay_wx

Marketing - new Mustang with the "same" engine as the old one? While it would have possibly been better for insurance purposes, it very well could have hurt sales. Not to mention the first time a car magazine tested one they would report that the track times and the hp figures didn't quite jive...but yeah the thought of lower insurance premiums is never a bad idea!

Knight

yeah its marketing...you would loss lots of sales of the non enthusisut if it read as 260hp.

theedge67

Yeah, I can go get a 4 door econobox with darn near 260hp anymore.

Thunder Road

You can take numbers and make then say what you want. But these 11 dyno test you have, came from various altitudes, various temps, humidity, Air Density. All variables that greatly affect hp rating at that moment. Try to dyno your car multiple times and come up with the same numbers every time. Not to mention 11 out of thousands is hardly represenative. Mass produced engines flucuate greatly as to horsepower. What you can say for sure is every 05+GT has 300 hp minimum at the fw, and those engines that just happen to have good centerlines on the bores and crank, and just happen to be balanced to a higher degree than others make a good bit more than 300fw hp.
No controlled dyno test on these 11 cars + way to few representations = no way to make a definitive statement.
As to why the Shelby GT was changed from 325 to 319, I would speculate, which is all we can do, Ford softened the tune. My 05 Five Hundred is rated at 203 hp. Why? I would only be able to guess, that is the lowest hp output Ford would expect from the motor as it comes in the car, but many cars will have more.
I would tend to believe the 15%.

PlayMisty

Well, OK, I see your point, but someone who dynos cars every day and has been doing for several years seems like 'doing testing' to me. I originally asked him if the average losses on a manual transmission were about 15% and he said that it was closer to 12. He's done a Shelby 500 and numerous Vipers, plus several hundred others (all captured on the wall, with numbers). The S197 is no different to anything else. Averaged out over the years, with the numbers on the dynos compared to the manufacturer's claims, he's settled on 12%. Sure dyno readings vary a lot depending on a lot of parameters, as do outputs of nominally identical engines, but the mean value of a large sample gives you a 'test result' to work with. Or at least an informed observation. And that observation leads me to believe the GT is a little conservatively rated, which is a good thing.