Rear Wheel HP results

Well, here are the Dyno results on my GT. Kevin and couple of other people had indicated some interest in this.

First some info on the motor/Car and the Dyno shop.

Ford Motor Sports 345HP 302 crate motor from their catalog, Performer RPM Intake, Holley 650 DP, MSD ignition, GTD headers, Renault UN1, P335 X 35 X 17 tires.

The people at the shop were great. The Dyno used is a Dynamics Dynamometer. I was told from the begining 2 things; First, Dynamics test results are always 15% lower than Dynojet Dynamometers /ubbthreads/images/graemlins/shocked.gif and Second, the FMS crate motors are notorious for being under powered, even their big blocks /ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/blush.gif

The car was straped in, 3 pulls were made and the best one is as follows:

221.3HP at 5600 RPM (Dynamics), 254.9HP (for Dynajet)
250 flb at 3900 RPM (Dynamics), 287.5 flb (for Dynajet)

I was also informed that an older Diablo and a Modena had previously been run on the same dyno with 330HP and 300HP respectively!

After the test I sat down with one of the guys talked for 45 minutes about how under powered FMS crate motors are. He indicated that surprisingly the Chevy crate motors did better (Sacrilege). He also mentioned that a stock Ford lightining truck had posted great results while a big Ford 514 incher had been disappointing /ubbthreads/images/graemlins/confused.gif

I think the bottom line in all this, IMHO is that Flywheel horsepower can really turn out be useless. The bottom line numbers are what is happening at wheel of each ride.

I don't know how many people on this forum have actually put their cars on chassis dyno (Roy Smart and Rick Mertz are the ones I know, I think)?

Finding out the horsepower at the wheel is kinda like having a test done for Alzheimers, do you really want to know? /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/shocked.gif Can the ego take it?!

The car feels fast and moves like the devil, but I can't help thinking how it would have been If FMS wasn't full of SHIT as it often is /ubbthreads/images/graemlins/smirk.gif

I believe the way to go is, tell the outfit you are buying the motor from, the motor will be Dynoed once installed in the car. And, if the numbers are grossly off, IT WILL BE SENT BACK COD /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

Good post Faili, it's rare for someone to bare all about their motor , let alone a low H.P figure (it's a boy thing /ubbthreads/images/graemlins/tongue.gif), good on ya.. but just think of all the power upgrades that you have given yourself perfect excuse to plan!! /ubbthreads/images/graemlins/smirk.gif

Great info, Thanks very much. It will be really interesting to see what you get when you run it again with the Webers.

I think one of the big problems with Ford crate motors has always been the Heads they use. They just don't use heads that are near as good as what you can get from the aftermarket. A couple of years ago Muscle Mustangs Magazine tested a Ford 393 crate motor and picked up an additional 75 HP just by changing to a set of AFR heads. I have seen that sort of thing repeatedly with other FMS motors.

In the November 2003 Issue, Muscle Mustangs tested a 331 with 10 different heads. The Ford GT-40X made 390 HP @ 5,400 RPMs and 416 ft lbs @ 4,400 RPMs. The AFR 185s made 448 Hp @ 6,100 RPM and 445 ft lbs @ 4,300 RPMs. Everything besides the heads was the same.

Probably the best way to do it is to try to by an FMS short block and put AFR or TFS heads on it. A little more money that way, but a lot more power.

Thanks again for the info,

Kevin

So I take it this dyno is an eddy current setup rather than inertial? I've heard that the Mustang dynos (eddy current) give lower results than DynoJets, but I don't think the difference is as much as 15%.

Do you know where the single biggest power loss is between your flywheel and the dyno rollers? It would be the tires. And spooling up those big 335 meats won't do wonders for your dyno results. Still, 250 rwhp in a 2,400-pound GT40 is like 365 rwhp in a 3,500-pound Mustang or F body.

I would agree with Kevin that if you want to unleash some more ponies you should bolt on a set of AFR 185s.

[ QUOTE ]
I think the bottom line in all this, IMHO is that Flywheel horsepower can really turn out be useless. The bottom line numbers are what is happening at wheel of each ride.

I don't know how many people on this forum have actually put their cars on chassis dyno (Roy Smart and Rick Mertz are the ones I know, I think)?


[/ QUOTE ]

I have and completely agree with you - flywheel numbers are useless. I just got back from putting the Lotus on again this past Thursday - 289 hp, and 285 torque, rear wheel on the Dynojet - off the spray. On the spray, well, we're not done tuning but it's looking good!

These are great tuning devices but they break lots of egos. Of course, it works the other way too. The shop I go to has the 400, 500, 600 club and there are some suprises. In the 600+ club reside a couple of late model Toyota Supras wihch have amazing turbocharged inline 6 motors that are turning out some serious hp. My goal is to get the little Lotus 2.2L 4 into the 400 club off spray, which I think we can do with some more work.

Nice work on your car and motor!

R

I currently have a Classic Roadsters Cobra with a 393 stroker and had it on a chasis dyno at the last DVSF. It's nothing special, stock rods, 9:1 Keith Black pistons, Comp Cams hyd flat tappet cam, Edelbrock Performer rpm intake and carb, and low price cast iron Roush 200 heads. The heads have good flow with 2.02 intakes and 1.60 exhaust valves. Tires are 255/60-15's and I made three runs at 360 rwhp. Torque was 398 ft. lbs. Not bad for a low price stroker in a 2500 lb car. You can buy a pair of cast iron Roush 200's for about $800. Worth a look at.

Jim Downard

Fred you should remember that you are using the stock GTD muffler. The inlet side of that muffler has holes that are aprox 21/4 inchs in diameter whereas the outlet of the collector is 3 inchs. This mismatch alone in the exaust must cost you at least 25-30 hp. The rest of the muffler is worse. I would love to bolt my mufflers on your car and see the difference.

Thanks guys for all the responses. Mark, I think you have a valid point on the tires (not enough though to get FMS off the hook with their bogus HP claims). The 15% add on for Dynojet was what they told me, +- few % I am sure.

Ron, getting the HP that you want out of your Lotus shouldn't be too hard. All the cars at the Dynoshop that put out big HP numbers were 4 bangers with turbos. The owners race car was a Supped up Subru all wheel drive. By the time you are done with your Lotus, your GT has to put out some serious Power to keep up!

I think if most people on this Forum chassis Dyno their cars, the info gathered could help everyone make better choices. There are 4 guys that I know on this Forum that have nearly identical motors as mine. It would be great If they would Dyno theirs and post the results. But as Jools correctly mentioned, It's kind of "boy thing".

After reading everyone's posts, the AFR 185 (Or any head other than GT-40 heads) is the way to go. There is an article in KIT CAR Magazine about a 302 with AFR 185s putting out 432HP at flywheel (I know another flywheel number /ubbthreads/images/graemlins/smirk.gif). Hey, at this point if I get my car to post RWhp at above 300, I will be happy. /ubbthreads/images/graemlins/cool.gif

Any body need the FMS GT40 heads for use as dead weight /ubbthreads/images/graemlins/crazy.gif

Howy, I saw your response after posting the reply. Forget about the muffler. you have the same motor, come on lets dyno your car, it's 2 minutes from your house /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

We could make a forum section for dyno results, I like that sort of thing. Not because I want to see numbers but because I feel it is the best tuning tool around. Bench racing isn't any good, but the dyno numbers are more than for bench racing. Each time to change or tweak something on my cars I'm always out to optimize it. Anyone want a dyno section? It'd appear under the technical header and I'd like to see some dyno plots in there as well.

Ron, I think it would be a great thing, if people participate that is.

Just think about it, If I Re-Dyno a month from now with AFRs and get different numbers and then the same with Webbers, The info should help some one.

You're on Fred! As soon as I get it together after paint we'll have a dyno party! I'm gonna guess I've got another month to 6 weeks of body work left. I am trying to get in at least a hour a day after work and several more on the weekends but this is very slow work. I'm done with the sills, and the front and back clip. I have finished about 80% of the drivers door including removing the bump. All the time goes into taking off and replacing the door over and over for fit. Its slow and now I know why the body guys want so much money. After I finish the driver door it's on to the other door for the same thing and then a little work on the roof for the door fit lines. Then a over all final fit and sanding. The paint guy says he will have it for about 3 weeks so I'm still shooting for the first of summer.

You guys who are going to do your own body prep/fitting, DO NOT UNDERESTIMATE IT!!! I started right after Christmas and I would guess I have spent at least a dozen hours a week on it since with at least 6 weeks to go. Figure at least a couple hundred hours.

Fred the dyno thing will be fun!

I think the heads will help but youi're not going to beat a 4bbl for power production. The properly setup Webers and 4bbl should be on top of each other, as shown eariler on this forum. That being said, I'm using Webers because I like the look. Personally, I don't think they'll be as drivable as a 4bbl nor will they produce any more power - just for the wow factor and sound I want them.

Ron, I totally agree. All the tests I have seen regular 4bl has done the job. I have the Webbers for exactly the same reason as yours /ubbthreads/images/graemlins/cool.gif

Well, at least we got Howard signed up for Dyno. Although, he does not need to wait for the paint to Dyno /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

I suppose this is just about like beating my head on the wall, but we are going to dyno the engine for my car (mostly to try to dial in the Webers) before it goes in the car- and dyno the completed car afterwards. I agree that chassis-dynoing is the way to go, because it looks at everything- engine, drive train, and wheels and tires. As a matter of fact, the Mini-Cooper guys don't bother with engine dyno at all- it's hard to imagine how you could hook up a Mini engine since the transmission is in the oil pan, at least on the old ones like mine. Those guys are all about chassis dyno hp, and they see results right away. What are typical costs for getting a car on the chassis dyno? There are not a lot of facilities in my area that I know of.

Faili, I forgot to mention, you have my sympathy on the FMS motor performance. This is not the first time I have heard that Ford crate motors are pretty anemic out of the box. The Ford books I have seem to agree. I found that AFR heads are not easy to come by- everyone wants them this time of year. I got mine from Ed Curtis at Flowtech in Rhode Island; nice guy, fair price, but they took a while. On the bright side, once you've changed heads, you will have two dinghy anchors you can advertise at BoatUS or West Marine if you live near the water. /ubbthreads/images/graemlins/grin.gif

Hey Jim,

The cost was $90 for three pulls. I did not do any tunning or Air/Fuel ratio adjustments (No need to bother with these heads /ubbthreads/images/graemlins/smirk.gif). After the runs the guy was nice enough to sit down and talk for an hour for no charge. The cost can run up to 300 to $400 If you realy want to dial everything in and let them tune your motor.

By the way, I don't even think the boat guys would have any use for these heads, not heavy enough for even "that purpose" /ubbthreads/images/graemlins/grin.gif

There are a lot of places in the MD/DC area. Here I pay $65 for 60 mins, which usually is about 3 pulls with fiddling. Not bad really. Just ask around at speed shops and you'll find the dynos eventually. Or, check the yellow pages under automobile performance, you should get some that way. I think Dynojet might have installations on their home page too so it'd be easy to locate for you in the MD area.

Some of the Ford crates are consitently better than rated - the 385 hp 351 comes to mind. I've seen a number of these dynoed out of the box and they are usually in the low 400s. But, I've heard the same thing about the 345hp motor - it never delivers as advertised.

For what it is worth the rear wheel horse power results from dyno tuning my 347 wih roush cast iron heads was 342 hp
with strong and flat torque curve. See the results under the post 347 dyno results from my post in June last year.(hopefully the link is attached.)

Regards,
RV

http://www.gt40s.com/ubbthreads/showflat.php?Cat=&Board=UBB6&Number=22508&Forum=UBB6&Words=347&Match=Entire%20Phrase&Searchpage=1&Limit=25&Old=allposts&Main=22506&Search=true#Post22508

Hey Fred, what gear did they do that in? The reason I ask is the stock renault clutch you have may have been slipping. Pulling full power/revs in 4th or 5th might be too much for it. You should be able to tell by a sudden spike downward in power somewhere near max torque. Revs will spike up at the same time. Did they give you a print of the chart rev/ power,torque? Also was that max power at 5600? If so I really believe that your muffler is plugging things up. My motor feels like it keeps making more power all the way up to the 6k rev cuttout. Anyway we will give mine a try when I get it together. Right now I have no windshield, lexan, lights, door handles etc on the car getting ready for the paint shop.

FWIW, my dead stock '91 Corvette ZR-1 (350 cubic inch V8, 4 cams, 4 valves per cylinder) did 307 RWHP on a Dynojet. My original 427 S/C Cobra (medium rise heads and intake, single 4 barrel carb, motor untouched for many years) did 304 RWPH on another Dynojet. GM engineers use an 18 percent loss factor for manual transmission drive trains.