Very disappointed with my 347 dyno!

8850 · 01-09-2001, 09:08 PM

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

302 LX Eric · 01-09-2001, 09:25 PM

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

------------------
1991 5.0 LX Coupe -37,800 miles

13.17 @ 106.14 mph w/ 2.138 60'

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

Rev · 01-09-2001, 09:40 PM

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

Rev · 01-09-2001, 09:45 PM

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

8850 · 01-09-2001, 10:21 PM

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.

Rev · 01-09-2001, 10:31 PM

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

jimberg · 01-09-2001, 10:51 PM

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.

------------------
351W 89 Mustang GT Convertible

8850 · 01-09-2001, 10:55 PM

Rev,

MTI is Motorsport Technologies Inc.

8850 · 01-09-2001, 11:00 PM

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.

01-09-2001, 11:18 PM

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.

jimberg · 01-09-2001, 11:26 PM

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.

------------------
351W 89 Mustang GT Convertible

8850 · 01-10-2001, 01:14 AM

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).]

FivepointOH · 01-10-2001, 01:31 AM

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...

------------------
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

Nicks5.0 · 01-10-2001, 01:46 AM

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

Skyman · 01-10-2001, 01:54 AM

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

------------------
-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...

01-09-2001, 09:08 PM	#1 (permalink)
8850 Registered Member Join Date: Nov 1998 Location: Sugarland, TX USA Posts: 161	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

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01-09-2001, 09:25 PM	#2 (permalink)
302 LX Eric or '331 LX Eric' Join Date: Jan 1999 Location: Columbus, Ohio Posts: 2,142	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 ------------------ 1991 5.0 LX Coupe -37,800 miles 13.17 @ 106.14 mph w/ 2.138 60' Pro-Charger D-1SC on the way!!!

01-09-2001, 09:40 PM	#3 (permalink)
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	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

01-09-2001, 09:45 PM	#4 (permalink)
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	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

01-09-2001, 10:21 PM	#5 (permalink)
8850 Registered Member Join Date: Nov 1998 Location: Sugarland, TX USA Posts: 161	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.

01-09-2001, 10:31 PM	#6 (permalink)
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	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

01-09-2001, 10:51 PM	#7 (permalink)
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,088	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. ------------------ 351W 89 Mustang GT Convertible

01-09-2001, 10:55 PM	#8 (permalink)
8850 Registered Member Join Date: Nov 1998 Location: Sugarland, TX USA Posts: 161	Rev, MTI is Motorsport Technologies Inc.

01-09-2001, 11:00 PM	#9 (permalink)
8850 Registered Member Join Date: Nov 1998 Location: Sugarland, TX USA Posts: 161	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.

01-09-2001, 11:18 PM	#10 (permalink)
stanglx347 Posts: n/a	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.

01-09-2001, 11:26 PM	#11 (permalink)
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,088	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. ------------------ 351W 89 Mustang GT Convertible

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01-10-2001, 01:14 AM	#12 (permalink)
8850 Registered Member Join Date: Nov 1998 Location: Sugarland, TX USA Posts: 161	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).]

01-10-2001, 01:31 AM	#13 (permalink)
FivepointOH Registered Member Join Date: Jan 1999 Location: Sugar Land, Tx USA Posts: 478	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... ------------------ 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

01-10-2001, 01:46 AM	#14 (permalink)
Nicks5.0 Registered Member Join Date: Jun 2000 Location: Belleville Il, USA Posts: 234	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

01-10-2001, 01:54 AM	#15 (permalink)
Skyman I need 110mph Trap Speed! Join Date: Feb 1999 Location: So, CA Posts: 4,315	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 ------------------ -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...