Well I had the car to the dyno(mustang dyno) Friday, it was Very hot and Humid here and the new 355 did not live up to my expectations... I'm sure that some of the trouble was the weather, but the engine stopped pulling at 6100 and HP fell like a stone down a well.LOL. The GM 847 should make power to 6800..Ion's having a look at the dyno charts and Data logs, but I'm thinking it's my Pacesetter Mid length headers, as the A/F where right on.

I ordered Pacesetter Race long tube's and an off road Y today and hope that will help, but I'm mot sure, anyone gone from Mid's to Long tube's in a High revving engine?

I'll post the numbers when I get this sorted out......

 

I doubt your headers are the problem. At least the way your describing the way the HP dropped. They (dyno numbers) must be pretty bad if you keeping them a secret

 

Why can't you just post the numbers?

The headers are not your problem.

 

Heads went sonic? Or valve lash set really really tight?

 

I didn't dyno it but my car went 11s with midlength headers, IMO headers are grossly over benchraced.

Without seeing the graph or really knowing much else I will throw out a guess of inappropriate valvetrain, something like wrong spring or wrong installed height on the spring, without knowing history could even be worn out springs.

 

The "weather" should not be a major factor. The results should be corrected to "normal" HP and torque values, using either "STD" of "SAE" correction factors. That accounts for temperature, humidity and barometric pressure.

 

Just throwing this out there but could the 847 cam been packaged wrong? And you ended up with a 845 cam?
This is why I only mess with custom cams and everytime I degree the cams I have an accurate cam sheet to. Go off by to let me know to see how wrong I set it or how right they were after degree'd lol

 

intake manifold have any porting ?

 

On a Mustang Dyno,It made 353 "SAE" corrected, which was higher than the NON corrected number of 352. The guy operating the dyno said he had never see a corrected # higher than a non corrected. The car would just hit a wall at 6100 and hardly rev any higher. But out on the street it will scream to 7000 so quick I have to be careful not to over rev it. The valve springs are new, and installed right, by a local shop, and there new stock lifters adj 1/2 turn. The intake is just gasket matched and cleaned up some. The numbers on the cam where right and I bought it off a member on here used but lightly, but I did not degree it, dumb I know, but I didn't have the stuff to do it with and no one to get it from.

Two years ago I was to a Dyno Jet and I made 371 and last year I made 317 on the Mustang dyno with the exact same set-up. I think I'll go back to the dyno Jet one and see what happens...

 

Mostly because I do NOT want to read what your going to type about my cam choose.... That and NO ONE post Mustang Dyno numbers..... but I just did.

 

Take it to the track and see what it runs. The track seems to provide a more accurate measurement of where the car is performance-wise!

 

Dyno's are for tuning. Just because the Dynojet might give you a higher number than the Mustang, did it really make more power? No.

Read this article on chassis dynos: http://www.hotrod.com/techarticles/g...ing/index.html

 

Are you using stock heads? Any work done to them? I dont think the stock LT1 heads can keep up with that cam at higher RPM. I think that is your problem.

 

He has LE'2
Since you live in new brunswick I have a fellow friend up there he is a cop that drives a 2011 orange boss. Lol probably all the reason not to talk to him but he is an awsome guy and has his own shop that might be able to help ya degree that sucker and maybe help ya sort your disappointment he goes by tje name joe delong. You can tell him art sent ya his way lol

 

Just heard from my Ion, and he says that according to the datalog I sent him the car is lean not rich. There's something wrong with the Mustang dyno and the owner of it has cancelled all future appointments until he gets it sorted out. I'm going to the Dynojet this Friday to see what his shows for A/F. I don't want to burn it down, that could be the reason for the drop off in power at 6100, well see.