Very disappointed with my 347 dyno!
 

I took my 347 to MTI's dyno today. Needless to say I am very disappointed. Here are my results of rpm verses hp. No torque values were calculated as they told me the dyno doesn't read torque sometimes with slicks.
2900 rpm 295 hp
3400 305
3900 309
4350 322 Peak
4800 305
5300 300
5800 260
6000 220

Nothing but down hill after 4350.

My LS1 with stock cam, stock throttle body and intake makes more hp than this. I see why shifting at 5000 rpm gives me .3 better et than shifting at 6000.

I'm ordering a set of 1 3/4 headers tomorrow! Maybe my 1 5/8 shorties are the problem. This cam is suppose to pull to 6500. My Cobra intake has been killer ported.

My daily driver makes more hp than my trailer car...Boo!

Here are my mods:
88 347 n/a,ASP race underdrive,Pro-M 77 MAF w/30# injectors and ASP extra long air filter/adaptor,190 fuel pump,Ported Cobra U&L,CNC and ported Twisted wedge heads(9.9:1cr),Comp Cams 224/230 @ .050 w/.550 lift,stock block,Mac 1/5/8" shortie ported headers,2' straight pipe exhaust,ASP steel solid motor mounts,Hoosier slicks,Lakewood 90/10,Eibach drag springs,3.27 gear,C-4 with reverse manual valve body,#6 pump PI converter,Crane HI-6,2420# race weight

Dude, sorry to hear about the disappointing dyno results. It really doesn't even sound correct. I mean, a n/a 347 with 9.9:1 comp, 30#'s, decent cam, etc and that's all it can muster? And what is this crap about slicks and torque? I have never heard of that. What kind of dnyo machine do they use? And how much did they charge you?

I hope you get it worked out. Good luck and keep us posted.

E

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1991 5.0 LX Coupe -37,800 miles

13.17 @ 106.14 mph w/ 2.138 60'

Pro-Charger D-1SC on the way!!!

Somethings definitely wrong here. Horsepower is a function of torque at various RPM's. If the dyno can't measure torque, then I don't see how it can measure horsepower. I'll bet if you try adifferent dyno, you'll get better data. Unless the slicks were spinning on the rollers, that shouldn't matter much. Weight of the wheels/tires might affect the outcome, but that would be a reflection of driveline efficiency. I'd put on some street tires and try a different dyno facility. There should be no legitimate reason why the dyno would not show torque. At least that's my reasoning.

Rev

Also something wrong with the peak hp, as you are aware it should be much higher in the rpm range. This is definitely a brain teaser.

Rev

The technician told me that slicks expand causing the dyno not to be able to read torque. He also told me they were holding good to the roller.

I do feel the hp verses rpm are probably correct as I ran .309 slower taking my engine to 6000 rpm verses shifting at 5000. And this was with a better 60' on the slower(6000)run.

I paid $75 for the dyno. They did three pulls and with a wide band 02 sensor installed to check fuel mixture. Not sure what brand dyno they have. I thought this was reasonable.

Right now I feel that my 1 5/8 shorties is the culprit. I am ordering 1 3/4 tomorrow and will give them a try.

Eric,

I agree with you that this engine should pull much higher than it does. Comp Cams told me this cam should pull to 6500.

Rev,

Yes, I know the hp should be much higher than 4350 rpm. My engine has a problem.

8850, I'm from Houston. Where did you have the dyno done? Call the guys at TNT Automotive and check on that torque registration thing. They use a Dnojet. That's where I get mine done. Same price $75. Not saying that your place is bad. Why not put street tires on and try it that way? They should give you a break since you didn't really get a proper readout. Just a few thoughts.

Rev

Part of your problem is that your intake runners are too long for the power band your cam supports. Remember, long runners are geared to more torque at the lower end. 6500 rpms is way out of range for a Cobra intake. You should have a shorter runners. A box intake would be easy since you already have the lower intake, but a Trick Flow (The one that is comparable to the 351 intake) intake might do a better job.

The people doing the dyno tests clearly don't understand what torque and horsepower are so I would take it elsewhere. Torque is measured, horsepower is calculated. If the dyno can't measure torque, you can't calculate horsepower.

Regardless of what the actual numbers are, your peak horsepower is probably at the correct place. 322 RWHP isn't shabby for what you have, btw. You're putting out 380+ HP at the flywheel.

I wouldn't worry about your exhaust. That's not your problem at this point.

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351W 89 Mustang GT Convertible

Rev,

MTI is Motorsport Technologies Inc.

jimberg,

I sure hope the problem is not headers and intake. I can't put out the money for both right now.

I sure would like to try a box upper before spending the money and it not work.

I agree 322 is not too shabby at 4350 rpm but it should continue to rise at least to 6000 with this cam. This is why I feel I have a problem. This engine has potential, hopefully.

Your combo is very, very similar to mine.

I run a 347 but with TF Street Heats and 10.5:1 compression. When I switched from a GT40 upper to a Down's Ford Box upper my ET went from a 11.70 to a 11.59. I changed nothing else, so I recommend a Box upper. Well, I might recommend a gear change, I also am running 4.10. A big difference from your 3.27.

I don't think it is your exhaust at all. I just meant that some day you will be breathing so well that you will eventually need exhaust improvements. I don't think that will happen until you add nitrous or a blower.

I'm actually suffering from the same problem of having runners that are too long. I have a GT-40 intake on a 351. I hope to get the Trick Flow intake at some point.

For you, either the Trick Flow Track Heat or the R-series should be good. The problem is that they will run you $450 to $500.

The less expensive alternative would be getting a new cam that goes better with your intake setup.

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351W 89 Mustang GT Convertible

stanglx347,

Send me your box upper and I'll give it a try. haha! If I had 4:10 gears I wouldn't come close to making it to the finish line. I am turning 5800 right now with this 3.27 at 120 mph. Remember I have a loose converter.

jimberg,

Have you had yours on the dyno with the GT40? Would be interesting to see if yours dies at about the same rpm as mine.
I was planning on the Victor 5.0. Do you think the Trick Flow intakes are a better choice? The Victor has a 75mm inlet which would match my 75 throttle body.

[This message has been edited by 8850 (edited 01-10-2001).]

Man that sucks, I don't understand how you are running a 121 trap speed and only making 322rwhp though? I know your car is pretty light but still seems like it should be a lot higher...

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92 AOD GT, K&N, ram air, pulleys, 2 ch. flowmasters, 4:10's, shift kit, 1 5/8 mac longtubes and offroad hpipe 14.249 @ 97.34 mph before the headers and hpipe

8850, i have read the last couple of your posts and watched that vid you put up here of your car, sounded killer. back to the point though, the cobra intake you are running is designed to run out of steam at 5500rpm in a 302, the extra inches just lower that rpm range, even if it has been majorly hogged out, the long runners are way out of sync with your cam. i say ditch the intake first...i have heard good things about the new TFS intakes and edelbrocks are proven pieces. the victor might be to large for you, but the only way to know for sure is to check and see, i would think it will be an improvement over the cobra though. MM&FF just tested the victor on a solid roller'd, high comp 347 and they said the intake's potential couldnt be realized even on that motor, so you might want to look at the Perf. RPM first. just an idea though. i would worry about the intake before you get the long tubes if you are on a tight budget. just my opinion though. sorry this is so long, nick

I agree if they cant read torque they sure as hell cant get your HP! Screw that dyno shop they are retards.

Don't count anythign they have said untill you get the right numbers. I agree on the intake though too.

Skyler

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-1989 Saleen Mustang #406-
TFS Heads, Edelbrock intake, E-303, 3.73's, 1 5/8 shorty headers, Offroad-Hpipe, 2chamber flows, 36psi FPR, playing with timing still, 70mm tb, 73mm maf, 24lb injectors, K/N, March Crank pulley, MSD6a, 9mm wires and FMS Aluminum driveshaft.
Best ET 13.2@106mph Needs tuning...

Nicks5.0,

I was going to go with the Victor 5.0 because it is the only intake I know of with a 75 mm inlet to match my 75 mm throttle body. Do you know of another with a 75 opening?

Skyman,

I understand what you are saying but MTI's hp numbers do correspond to my track times. Take a look at them. On the first run I shifted at 5000. The second a little higher and on the third all the way to 6000 and I slowed by .309 seconds. This pretty much agrees with dyno hp.
http://www.fbody.com/members/LarryS/347times.jpg

If you use the stang analizer, Your last motor did not break 300hp. The new one comes in around the same as you dynoed. I did this as soon as you posted the first track results. I would not worry about the numbers, look at the 1/4 mile times that you run compaired to every one else. That is why I PM-ed you about the weight. I am going to get down to the same as you. You may also want to try the box style upper.

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Jason B Johnson 88LX,speed density,edel heads,4.30s,B-303,cobra,tremac,
12.38 @ 111.28 1.80 60ft 28X10 street tires
12.17 @ 112 26 X 10 slicks
http://www.mustangworks.com/mustangs/pictures/Listing347-slot3.jpg

Sorry, never had it on the Dyno but I'm pretty sure it dies well before 5500 rpm.

You didn't list that you have a 75mm TB. I think that is probably too big for what you have. Even so, the 77mm MAF meter is too small for that throttle body size. You should probably have an 83-87mm MAF meter.

As for the Victor intake, I thought it was pretty expensive and is really designed for a high reving engine (4000-8000rpm powerband). The Trick Flow stuff is less expensive and a better match for your setup. They also flow great out of the box. If you want to go with Edelbrock, the Performer RPM is probably a better match.

The Trick Flow R-series is probably the best match because of the 347.

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351W 89 Mustang GT Convertible

8850,

Just wanted to comment on a couple of things. My converter will 'flash' to ~3900 and I shift into 2nd and 3rd at 6100rpms, crossing the 1/4 mile at ~6200 rpms.

I saw mention of the Trick Flow Intakes in this thread and cannot recommend them, I tried both the Street and Track Heat intakes, both upper/lower match ported to my Street Heat Heads. I lost HP, MPH and 1/4 time on both intakes.

GT-40 11.70's 114mph
Street Heat 11.99 111mph
Track Heat 11.90 111mph
Downs Ford Box upper 11.59 115mph

All of this was done with a period of about two months and no other changes in the car. The weather at the Track was it's best when I ran with the Trick Flow Intakes.

If others have better luck with those intakes, then Good, glad to hear money well spent. In my case, I didn't not have a good experience.

stanglx347,

Would be interested in knowing what heads, cam, compression ratio, etc. that you have with this box.

I picked up a box upper today and will be dynoiing it tomorrow if the weather gets better. At least if I pick up in the upper rpms then I will know it is the intake and not my headers.

i just finished reading the jan 01 issue of MM&FF &they made 475hp@6500 & 422lbs-ft@510 with the trick flow R series intake. it is made for higher rpm's (2500-6500). it improved hp on their motor by 25 hp at 5500rpm over the gt-40 but torque fell 25hp.
they had afr185 heads, comp cams xe 292r cam, 10.5 comp, 70mm t/body, 77mm maf &36lb injectors

It Was A 347 stroker

I just sold my tfs track heat intake and I would say it was an ok intake but I think you can do better for the same amount of money. I also had to cut the throttle cable bracket to make it fit.

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James Cox
nochevy@hotmail.com
1991 Mustang LX
Best 1/8 time on motor 7.686 @90.20mph

I am thinking that if this box changes the top end power like it should be and I don't lose low end too drastically, then the Victor 5.0 would give me even more top end and get back some of the low end loss that I will probably experience with the box.

Sound reasonable?

stanglx347,

Looks like the box worked pretty good for you. If that is the case I might just keep the box. Just depends on how the low end shows up on the dyno. You got to have torque at your stall speed in order to get a good 60' time. I have a 3200 stall so I got to get torque pretty close to that rpm or my 60' will suffer.

Hmm, all I can say is that something is drastically wrong with that cam and 347 to be making power soo low. Once you get it all sorted out theres no reason you shouldn't pick up an easy 60-75hp, seeing that you will move up in the RPMS soo much.

low 10's maybe?

Skyler

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-1989 Saleen Mustang #406-
TFS Heads, Edelbrock intake, E-303, 3.73's, 1 5/8 shorty headers, Offroad-Hpipe, 2chamber flows, 36psi FPR, playing with timing still, 70mm tb, 73mm maf, 24lb injectors, K/N, March Crank pulley, MSD6a, 9mm wires and FMS Aluminum driveshaft.
Best ET 13.2@106mph Needs tuning...

Skyman,

Low 10s sounds good to me. I really think it is possible too. An engine that is making 220 hp at 6000 rpm and running a 10.71 is pretty good. Of course the way this thing pulls at the lower rpm I must be making over 400 pounds of torque already. If I could move it up it has to improve my et. My engine is a monster when I punch it at 3000 rpm in second gear. First gear is wasted but in second even with slicks on the street I'm all over the road spinning.

8850

My combo is as follows:

Trick Flow Street Heat heads, mildly ported.
1.72 FMS Rocker Arms

Lunati Cam ~550 lift and duration ~240 (I could be a bit off on the cam specs, it has been almost six years since the cam was put in sorry)

C-4 w/Trans Brake
~3900 Converter

Long Tube Headers...3" exhaust.

4.10 Gears

77pro MAss Air
30lb Injectors
190lb Fuel Pump

And a bunch of the regular stuff, MSD Ignition, CRANE Add on computer, shocks, frame connectors, battery in trunk, pulleys...all that stuff.

Ohh, just a couple of things...I already mentioned.

The lower is off an Explorer and I had it ported to the Heads. Now the interesting thing to note is that the Box upper has yet to be match ported to my 75mm Throttle body and to the ported Lower. So when that gets done it should help some more.

By the way, I might be looking to sell this setup as I am......*GASP*....going to a Carb Setup. No big deal really, I finally had the money to build a very, very radical motor and I am not very crazy about Programming Fuel Injection to get this setup to run.

So I may be posting stuff over in the Classifieds.

stanglx347,

Thanks for the info on your mods. Maybe I should have gotten the Down box.

This Comp Cam box is one PITA. First, I had to port the inlet to 70mm. It had a very small hole. The two tb and EGR gaskets were different diameters, both too small. One gasket had to be ground as it had metal in it. Why didn't they make this thing for a 70mm inlet? The six hold down bolts were too short. I bought six more the correct length and now all six won't screw in because of alignment with the holes in my GT40 lower. Also my regulator has interference with the box. Don't know what to do there yet. I will have to drill the holes larger and see if they will screw in. Looks like to be about 1/16 to 1/8 spaced wrong. I know my intake is right because I have used a Hogan box on this same intake when it was a 302 and the bolts fit fine.
And after all this, it is probably not even the problem.

I called Comp Cams today. Their expert told me to retard it 4 degrees from where I am. That would put it at 1/2 degree retarded. It is 3 1/2 degrees advanced right now. He also told me this cam should pull to 6500 rpm with a 347 if degreed properly. He said it is not my intake or headers. He said my engine would make more hp with a better intake and larger headers but the fact that it is falling off the way it is, is an indication of degreeing and not intake or header.

Right now, I don't know what the hell to believe. I have been told fuel, timing, ignition, intake, headers, valve springs. I am not sure who knows what they are talking about.


I'm going to try the box, if I ever get it to fit properly, as I have already paid good money for it. I'm not buying anything else until I have a little more confidence of what is wrong.

This 347 has been one fustrating project from start to finish!

Did you install the cam or what? Is there anyway to check the degree on the cam? I have always wondered how mine was in, because I dont know how it is degreed either.

Skyler

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-1989 Saleen Mustang #406-
TFS Heads, Edelbrock intake, E-303, 3.73's, 1 5/8 shorty headers, Offroad-Hpipe, 2chamber flows, 36psi FPR, playing with timing still, 70mm tb, 73mm maf, 24lb injectors, K/N, March Crank pulley, MSD6a, 9mm wires and FMS Aluminum driveshaft.
Best ET 13.2@106mph Needs tuning...

Skyler,

I had a pro to install a degree wheel before if closed my engine up. He put two solid lifters directly onto the cam and and indicator on the solids. He really knew what he was doing. I am almost to the assumption that the cam has been ground wrong. Maybe this box will tell me something. Yes, I did install the cam myself but had it degreed. I have the cam and timing chain gear marks straight up, matching, just as the cam came in.

8850...sorry to hear of the dilemma with the 347, but I would not chase any ghosts just yet. I would validate the original numbers first on a good dyno with someone who knows Ford stroker motors, combos, etc. Call Steve Drier at Houston Performance...he's just about a 1/2 mile south of the intersection of Tomball freeway and Beltway 8 in NW Houston. He can schedule you some dyno time on their 248C chassis dyno and Michael or Jason do a great job getting you good numbers. Before I did anything at all, I'd confirm the numbers on a good dyno at a reputable shop. They also have a data base their of customer cars and can usually find similar dyno runs with similar mods to make comparisons. They are intimately familiar with the 347 stroker...Highly recommend them!
Also, I had done crunched some numbers a few months ago on mnay combinations using Desktop Dyno 2000 just to get some ideas on which way I was going to go, and with the stroker combos. I noticed HP increase was not huge all other variables being equal, it was the TORQUE figures that skyrocketed!! Check my signature block for all the stuff I run...now with a 347 stroker, the net numbers were as follows:
peak HP @ 5000-5500 was 410 and dropped to 393 and 360 @ 6000 and 6500 RPM respectively. With a 20% loss thru the drivetrain this gave me 328 peak HP at the wheels. For torque, it was a whopping 470 peak at 3500-4000 RPM and with 20% loss netted 376FT-LBS at the wheels. My bet is you are close to these numbers with your combo. Call Houston Performance for some dyno time and professional recommendations. Good luck...Dave in Spring, Texas


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*92' GT, Keith Craft Racing 306 (10.25:1 CR), PRO-M 80mm MAF,65MM TB, Edelbrock U/L intake,
TFS-TW heads milled .056" (52cc chambers), CompCams XE274HR (.555/.565" lift w/1.6 rockers), A-351 adjustable roller rockers, 30# injectors,
Kirban FPR w/external pump, FRPP ceramic coated headers, Bassani X-pipe w/cats, Bassani cat back, Centerforce DF clutch/T.O. bearing...MSD 6AL w/MSD distributor, Steeda Tri axe, aluminum D/S, 3.73's, w/Factory Five U/L control arms. Lakewood 50/50 shocks. Stee

over 40 five oh driver,

You have a good idea. Before I start buying anything I need good dyno numbers with torque reading. Thanks! The dyno numbers I got from MTI were only from a graph and I calculated the numbers from the graph. But they do kinda correspond with what my car did at the track.


[This message has been edited by 8850 (edited 01-12-2001).]