lost a bit of torque with mrt catted h and jlt cai

[trendkilllx]

I have an 03 cobra,2 run with original factory tune, and ran 2 seprate dynos,
old was with stock tune, anderson powerstack, mag catback, temp 87 deg
new is with stock tune, JLT CAI, mrt catted h, stock and mag catback, temp 95 deg.
Anyhow noticed lost some torque, possibly from the hpipe and peak numbers were not as good with the new setup. Temp was higher on second run also.
peak # hp tq
Old 403.4 396
New 395 389

Rpm horsepower tq
Old 2.5k 170 360
New 170 352

Old 3k 219 375
New 215 372

Old 3.5k 250 382
New 260 380

Old 4k 291 390
New 295 382

Old 4.5k 321 389
New 325 380

Old 5k 360 376
New 360 370

Old 5.5k 372 368
New 380 365

Old 6k 395 350
New 394 348

 

[trendkilllx]

I didn't get a a/f on my run without the jlt and mrt H-pipe but here it is now. Can the h and cold air be causing it to run to rich with the stock tune


dyno graph

 

[trendkilllx]

also noticed it was a bit lean at low rpm

 

[Fuerza]

Interesting, threads like them make me hesitate putting on my x pipe.

 

[Tucker]

Are you compairing runs made on one dyno against runs made on a different dyno at a different time?
It is impossiable to fairly compair results of 2 different dynos. Plus the weather was a bit different too.

It does look like your #'s are low for your mods though. You may want to look into a tune. No you "shouldn't" need one with what you have, but somethings up.
Jay

 

[davbrucas]

lowend torque loss could be a combination of the 2 mods. the JLT has a 4" pipe and at low rpms the air velocity is lower than stock...combine that with the decreased backpresure of the x-pipe you will see a loss in torque but a gain in hp. best way to solve that is with a larger lower pulley!

 

[Miamifan1354]

First, like Tucker said, you're doing 2 diff dynos on 2 diff days with 2 diff conditions.. Number aren't gonna be close at all.. Also, according to your A/F, your going way rich uptop, which is why your peak isn't like it could be.. According to the number in your post, you were as much as 10 hp more in the mid range, and you lost a little tq. With less cats, you may loose tq due to less back pressure. The big thing is that you're real rich.. Go get a tune and the numbers will look a lot better..

 

[tv's 03]

Old 3.5k 250 382
New 260 380

Old 4k 291 390
New 295 382

Old 4.5k 321 389
New 325 380

Old 5k 360 376
New 360 370

Old 5.5k 372 368
New 380 365

Horsepower = tq x rpm/5252

under this formula, it is impossible to have more hp at a given rpm with less tq at that same rpm. These numbers just do not make sense....its simple math

Who knows? maybe the smoothing factors are different or something, but the numbers do not make sense

 

[trendkilllx]

Yep they were diferent dynoes so not really a fair comparison. Someone with on 04 with stock Hpipe, K and N air injection and magnaflow dynoed the same day at 412 hp peak, not sure what the torque was. I think they have a newer tune so not as rich up top. also think they did use a smoothing factor.

 

[Emmerson_Biggins]

Horsepower = tq x rpm/5252

under this formula, it is impossible to have more hp at a given rpm with less tq at that same rpm. These numbers just do not make sense....its simple math

I would like to take exception to this statement. So what you are indeed saying is that if I have a car that makes 498.52 HP 431.75 TQ at 5252 RPM, I make a small adjustment and re-dyno it less than a minute later and it makes 511.25 HP 431.32 TQ at 5252 RPM, that this is impossible?? It can't happen?? How do you figure?? I gotta hear this........

 

[MystichromeVert]

I would like to take exception to this statement. So what you are indeed saying is that if I have a car that makes 498.52 HP 431.75 TQ at 5252 RPM, I make a small adjustment and re-dyno it less than a minute later and it makes 511.25 HP 431.32 TQ at 5252 RPM, that this is impossible?? It can't happen?? How do you figure?? I gotta hear this........

If you made 431.75 tq at 5252, you would make 431.75 hp at 5252.

If you made 431.32 tq at 5252, you would make 431.32 hp at 5252.

The hp and tq curves MUST cross at 5252. Use a different RPM to make your point...

 

[Emmerson_Biggins]

ha ha , good job