1987 Shelby Daytona 1st dyno

[crow1970]

Hi all,

Just dyno'ed my Daytona and it pulled some decent numbers from the mild mods that have been done to the car, here is the link for the YouTube vid that I made.

http://www.youtube.com/watch?v=OWgLAyte7GE

[168glhs1986]

Nice car and sounds really nice. That has got to be one fun driver. How much to these weigh?

[crow1970]

I've gotten mixed numbers so apparently it weighs anywhere from 2,680 lbs to 2,812 lbs, thanks for the comment!!! Yeah it runs out pretty well although not blistering fast it certainly is damn peppy and good enough to beat up on some Hondas. And by the way I love your Consulier!!!!

[Turbodave]

Cool John, good numbers! I thought the car looked familiar then saw in the credits it was one of Paul's. If you can try to get it out to SDAC in a few weeks.

[Vigo]

Do you have a graph? I'd like to see the shape of the powerband with your 'mystery cam'.

Good numbers for 15psi, especially considering there are probably only 3 mods on the car that actually add power at a given boost level.

[cordes]

My thoughts exactly Vigo. Those numbers look good and I would love to see the chart. Nice looking car for sure. As Dave said, make it to SDAC!

[blk86trbo]

Neat video John, thanks for sharing that link! Here's an older thread from a while ago before you took ownership...

http://www.turbo-mopar.com/forums/sh...-Shelby-Z-pics

[crow1970]

I'm definitely going to try and make it out!

[crow1970]

Thanks for sharing the thread Paul, I appreciate it!

[crow1970]

Just posted the pics of the docs I got at the shop, the guy took it easy on the first pull, he wanted to make sure the car wouldn't move and also to get a feel for the torque steer. The second pull he mashed it but I lost HP due to the stock intercooler getting heat soaked

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[Ondonti]

That dyno does look a bit scary to sit on. Tiny roller.

[dwh4784]

Out of curiosity what were the mods and numbers? Youtube is blocked at work and I don't get online at home very often.

[crow1970]

They always factor in Weather Correction Factor, the computer said 199.4 HP @ 5463 and 203.2 ft lbs of torque @ 4737, if the guy had mashed it on the 1st pull I'm sure I would have hit 200. He also said that crank HP would be around 245-250. I wish I could dyno one that is bone stock to get a better gauge on HP loss that way I could calculate my gains more accurately. He said typically front wheel drive cars lose anywhere from 25%-30% through the drivetrain. I think a stocker would put down anywhere from 122-131 HP at the wheels calculating the 25-30% loss from the factory 174 crank horse power. The mods that were done are nothing major, I have an open stock 2.5" downpipe, MP comp, underdrive pulley, mystery cam (not sure of grind) I posted pics and the sheets from the dyno onto my profile, check them out if you get a chance.

[crow1970]

Yeah made me a bit nervous but at least it wasn't up on a rack, watched a few vids of cars getting loose and sliding off. Man I've watched your vids before, that duster kicks ---!

[Reaper1]

For the mods done I think the HP is pretty darn good. The torque seems way off. Unless that cam has a nasty profile to it (doesn't sound like it), the torque typically is higher than the HP number for our engines, especially mostly stock.

I honestly don't buy the 20-30% driveline loss. My V6 car running through an A604 put down 130hp and it was mostly stock (some really weak bolt-ons). With a 20% loss from 150hp it puts it right at 130hp. Given that the engine was extremely tired and had very little mods it wasn't making too much over the stock 141hp. My 1/4 mile times and speeds reflected this, and it was through an auto tranny. Put in a manual tranny and I'd bet the losses go down even more...probably around 15%. He's quoting numbers for RWD. They have more opportunity for losses than FWD.

My Z put down 225hp 291tq on 22#'s, +40% injectors, 255lph pump, AFPR, 5/16" fuel return line, Devil's Own water/meth injection, 3" exhaust with cat and Borla XR1 muffler, CAI, FMIC, adjustable cam gear, crank scraper, and Boost Button cal. The rest of it was completely stock for '88 TII.

This was good for 14.0@100 with a bad launch. So, it is/was (under construction now) a 13 second car. Stock the car ran mid 15's around 89mph.

My Shelby Z with a full tank of gas, full size spare, no big stereo (I take it out when I race) and me in it come in at 3115#'s on Longacre racing scales.

Just some things to consider. My car had a lot left in it with that set-up. I feel it could have easily hit 240 at the wheels and possibly 250 without opening the engine for hard parts or porting. That would put it well over 300lbft at the wheels.

[crow1970]

You know I thought the HP loss sounded high to me as well, he said he dyno'ed new VW's that put out 180 crank HP and at the wheels it was around 135, maybe his dyno is off. I did some research online and the consensus for loss is this, FWD 10-15% / RWD 10-18% / AWD 17-25%, I would like to think I only lose no more than 15%. Thanks for the info I appreciate it, your Tona sounds like a beast, power to weight ratio on these cars is such a contributing factor, nice and light.

[crow1970]

Here is a good article on drive train loss, anybody's guess is as good as mine as far as HP loss through the drive train.

http://www.modified.com/tech/modp-10...in-power-loss/

[Vigo]

My (informed, educated) opinion is that drivetrain loss numbers are totally misunderstood and usually overblown in an attempt to boost egos/results etc.

For one thing, 20-25% numbers are ridiculous to begin with. Maybe on a 100hp TBI daytona that's plausible only because the number you're taking a percentage of is so small.


The other thing is that the idea that that loss continues to grow in proportion to power output is also ridiculous. I think that trying to express it as a percentage leads to a lot of misunderstanding. It should take X power to accelerate X mass of the drivetrain to X speed in X time, affected by X losses to friction/heat. When you increase engine power you are accelerating the same mass through basically the same frictional losses in a shorter amount of time. So yes, it takes more power to accelerate the same mass in a shorter time period, but it's a very small effect on a 4th gear dyno pull of a low hp car where the drivetrain is not being accelerated very quickly to begin with. The frictional losses of the drivetrain dont change very much with power input, either.

So if you have a drivetrain that takes 15hp off of a 200hp motor, you can put 400hp through it and maybe now its losing 18 hp. It's a way smaller change than the internet makes it out to be. It's affected more by wheel weight than engine power.

[Reaper1]

I do tend to agree that it seems a bit off to say that the loss percentage stays the same for a 100hp driveline than a 400hp driveline (for example). The only thing is that friction doesn't change very much in the mechanical systems we are talking about. So the loss percentage isn't going to change much in a manual transmission regardless of power being sent through it. An auto is totally different as the are all kinds of losses that aren't linear. (I know he car in this thread is a manual, just throwing it out there)

One thing to consider is that your rolling resistance on a dyno is going to be more than on the street or track due to the car being clamped down more than the normal loading it would see. Tires also have an effect on this as well. Wheel weight can also play a part in how a dyno reads power, especially an inertial type dyno like a DynoJet. A water brake dyno will be more accurate in showing true power at the wheels. It can also show you driveline loss. Because of pricing and the popularity of the DynoJet, it can be difficult to find a water brake chassis dyno, but they are out there. I think FWD has one and if I'm not mistaken Dynapack dynos are also water brake type design (resistance based, not inertia based).