Bad day at Dyno!!!

MikeZ · 08-27-2004, 07:14 PM

After my recent exhaust mods, the butt dyno felt a big improvement, enough to motivate me to go for a dyno run.
Unfortunately, the numbers were less then impressive, actually less then JetTech stock dyno runs!!! The biggest thing that is puzzling is this dyno shows peak HP at 4000 rpms and JT's was at 4900, that is a HUGE difference, almost unbelievable. My first thoughts were I opened the exhaust too much but I doubt it. Second thoughts were the dyno is screwed up. I asked the owner and he said its fine.

They did 5 pulls and numbers averaged out to 239.7 HP @4050rpm, torque was 323.4@3600rpm.

Any other ideas? I could understand a 100 or 200 peak RPM difference but 900?

JetTech · 08-27-2004, 07:18 PM

I just checked the factory specs for the engine and the torque IS supposed to peak at 3600, so they are right on there and 323 is nothing to sneeze at. BUT heck no on the hp. I have no idea what they did wrong other than I think they forgot to disengage the parking brake...

Do you have the dyno run printout?

smoketitan · 08-27-2004, 07:27 PM

thats weird I thought most people were getting most of their power from the intake though?? do you have one??

and may I ask what size pipe you have for your exhaust?? and also what is the straight pipe idea?? got pics or a link ??

MikeZ · 08-27-2004, 07:30 PM

Quote:

Originally Posted by smoketitan

thats weird I thought most people were getting most of their power from the intake though?? do you have one??

and may I ask what size pipe you have for your exhaust?? and also what is the straight pipe idea?? got pics or a link ??

No intake, just K&N drop in. here is link about the exhaust mod

A new exhaust configuration!!

MikeZ · 08-27-2004, 07:32 PM

Dale, here is a couple pics one of printout, hope you can read it.

JetTech · 08-27-2004, 07:37 PM

ITS a MUSTANG DYNO!!! That answers all the low hp questions......

smoketitan · 08-27-2004, 07:41 PM

hmm wow you went pretty far back with your cuts (are the cats still intact??)--may I ask how the pipes exit the rear?? they route around the tire at all?? or come straight out the muffler. rather interesting--mine was a little different (mine are side out) as I have the 5x11 also. I can tell from experince if you arent happy, if you change out to the 5x8 (as I had the 5x8 first) you will get way more low end torque, but it will be a lot louder. the 5x11 gives more HP at the high end, whereas the smaller gives more torque low end. My local muffler guy told me that you will need to get a intake to get the most of the exhaust--working off the more outflow, more air in concept ---could be hogwash--but it seems to make sense,and feels about right on mine

thx for getting the dyno and posting it

pciley · 08-27-2004, 07:45 PM

Basically, you needed to have dyno'd the truck BEFORE you did any mods to get an accurate "performance gain" conclusion for your exhaust.

ALL DYNOmometers ARE DIFFERENT!

Did they have a big fan blowing on the front of your truck?
How hot was it (air temp) at they dyno place?

Yes, you will see higher gains when your exhaust is coupled with an aftermarket intake. Try out the new AEM intake.

Your horsepower numbers look low to me, but don't worry. I'm sure the results are just not ADJUSTED and all that, for temp, etc. Was the engine heat-soaked?

Find out when the dyno machine was last calibrated. If its been a while, they could be all out of whack or something like that.

You could try one of those "G-tech" performance reading devices that plugs into your cigarette lighter. Its got a built-in gyroscope thingy that tells you how much power, 1/4 mile time, etc. Its not the MOST accurate, but it will tell you if the dyno is fubar'd if the numbers it comes up with are WAYYY off from the dyno's numbers.

What kind of fuel were you using? How many miles on the truck? How many miles on the exhaust? Has the computer adapted?

MikeZ · 08-27-2004, 07:46 PM

Quote:

Originally Posted by smoketitan

hmm wow you went pretty far back with your cuts (are the cats still intact??)--may I ask how the pipes exit the rear?? they route around the tire at all?? or come straight out the muffler. rather interesting--mine was a little different (mine are side out) as I have the 5x11 also. I can tell from experince if you arent happy, if you change out to the 5x8 (as I had the 5x8 first) you will get way more low end torque, but it will be a lot louder. the 5x11 gives more HP at the high end, whereas the smaller gives more torque low end. My local muffler guy told me that you will need to get a intake to get the most of the exhaust--working off the more outflow, more air in concept ---could be hogwash--but it seems to make sense,and feels about right on mine

thx for getting the dyno and posting it

yep, cats are untouched. I have same setup now that Jet has except he is taking the 2.5 pipe and Y'ing into 3" collector which goes in to a single in 3" flowmaster 50 and then duals out 2.5. Dale also has a CAI but still cant imagine a peak difference of 900 rpms!

JetTech · 08-27-2004, 07:50 PM

Mike, I had no idea your dyno was accomplished on a mustang dyno until I looked at that sheet you took a pic of. The mustang dynos require a weight input and will use that number for constant resistance on the drums, thus causing lower numbers than a dynojet dyno will put out.

Your the first I think that has had a mustang dyno run accomplished. We really don't have anything to compare it to although they are supposed to be more accurate than the dynojets. Cool numbers and would have definitely been way higher on a dynojet dyno!! See, your butt dyno wasn't lying after all now was it...

MikeZ · 08-27-2004, 07:50 PM

Quote:

Originally Posted by pciley

Basically, you needed to have dyno'd the truck BEFORE you did any mods to get an accurate "performance gain" conclusion for your exhaust.

ALL DYNOmometers ARE DIFFERENT!

Did they have a big fan blowing on the front of your truck?
How hot was it (air temp) at they dyno place?

Yes, you will see higher gains when your exhaust is coupled with an aftermarket intake. Try out the new AEM intake.

Your horsepower numbers look low to me, but don't worry. I'm sure the results are just not ADJUSTED and all that, for temp, etc. Was the engine heat-soaked?

Find out when the dyno machine was last calibrated. If its been a while, they could be all out of whack or something like that.

You could try one of those "G-tech" performance reading devices that plugs into your cigarette lighter. Its got a built-in gyroscope thingy that tells you how much power, 1/4 mile time, etc. Its not the MOST accurate, but it will tell you if the dyno is fubar'd if the numbers it comes up with are WAYYY off from the dyno's numbers.

What kind of fuel were you using? How many miles on the truck? How many miles on the exhaust? Has the computer adapted?

Paul,
temp was 95 humidity was 70% (hot as hell), They did have a fan blowing up into front of truck. Miles on truck is 3000, miles on exhaust 200. I unplugged negative overnight last night and then drove 30 miles this morning before getting to dyno.

MikeZ · 08-27-2004, 07:53 PM

Quote:

Originally Posted by JetTech

Mike, I had no idea your dyno was accomplished on a mustang dyno until I looked at that sheet you took a pic of. The mustang dynos require a weight input and will use that number for constant resistance on the drums, thus causing lower numbers than a dynojet dyno will put out.

Your the first I think that has had a mustang dyno run accomplished. We really don't have anything to compare it to although they are supposed to be more accurate than the dynojets. Cool numbers and would have definitely been way higher on a dynojet dyno!! See, your butt dyno wasn't lying after all now was it...

Well that makes me feel a little better. I guess I need to come up to Atlanta and do the dyno same place.

He put 6000 for vehicle weight, a bit high I think. wonder if we can correct that number??? I know this baby has more power then it had stock but sure had me wondering.

Slurppie · 08-27-2004, 07:53 PM

Quote:

Originally Posted by pciley

Try out the new AEM intake.

You have any pics or info on the AEM? Not doubting you but AEM's site doesn't list anything for the Titan as of yet.

pciley · 08-27-2004, 07:59 PM

Yeah, AEM's site is LAGGING. The AEM release was announced by another user.. They actually had a Titan from this forum up at the plant in So Cal getting the fitments all worked out for the prototypes. Its out, can't find anyone who has it, call AEM directly at (310) 484-2322. They can tell you who carries it.
I am under the impression that it is one of their "Brute Force" model intakes for pickups/suvs.

SHould be aluminum tube (offered in different colors, usually red, blue, silver) and a K&N filter.

Nismo is said to be testing this for their line of aftermarket parts. Would be alot cheaper to buy it while its an AEM named product... If vendors are stocking it, try

truckperformance.com (its not listed, so you will have to call and get a product specialist on the phone.. might have it, but not updated the site yet)

JetTech · 08-27-2004, 07:59 PM

Quote:

Originally Posted by MikeZ

Well that makes me feel a little better. I guess I need to come up to Atlanta and do the dyno same place.

He put 6000 for vehicle weight, a bit high I think. wonder if we can correct that number??? I know this baby has more power then it had stock but sure had me wondering.

6000 is too much and would have caused more resistance on the drums than what was necessary. After taking all of this into consideration maybe you shouldn't come to Atlanta....you would probably shame us all on a dynojet...

Go here http://www.hondaswap.com/~pills/mustangvsdynojet.html for a more detailed explanation of the mustang vs. dynojet dynos..