Dissapointing day at the dyno

[sixty9cobra]

Wow guys great offers.Joe I appreciate the offer and will pay whatever the costs are and your time. When I built this engine I was expecting like 550hp so you can see why I"m a little disappointed. If I need a new manifold so be it. I was planning on 3" Magnaflows anyway. Is there a better muffler? Strait thru bullet? I like to drive it and want to hear myself think also. I'm going to Cecil County speedway in two weeks. I think I will make a few passes after I jet up a bit to 12:1 a/f. Then remove the shaker top, then the air cleaner altogether. Finally the exhaust that should be some good data. I'm working this weekend so I"ll look around work for a usable gauge I work at a national lab. If can inject a super collider with heavy ions I'm sure I can measure some back pressure and get back to you. I would really like to solve this dilema.

[Barry_R]

If it were mine I would invest an hour pulling the collectors open before I bought an exhaust system - six fasteners (or a sawzall & some band clamps) and you'll have an answer.  Intuitively I'd say the exhaust was hurting things and could be pulling the peak power RPM down a bit as things back up.  As stated in the FE forum response, I don't put too much faith in chassis dyno numbers, but directional tuning is useful with them.

[sixty9cobra]

I plan on doing just that at Cecil dragstrip on the 29Th Barry. I find it hard to believe there is 50 hp there or even 30 hp. If it was a stock exhaust maybe, but 2 1/2 ID and Flowmasters shouldn't be that restrictive. I agree the Flows rant strait thru design but certainly not like the original cross flow. What is the muffler of choice for the street racer these days. While I was at the dyno there was a Corbra and it had spintechs definitely not getting those. I might as well have just pipe they crackle to much. Jay what cam would you recommend? Also the Streetmaster should support 640hp according to you guys so it  would be worth it to have JDC look at it I think. In the meantime I'm going to try and look at the back pressure scientifically before I go. I'm tired of hit or miss should be an easy test.

[Joe-jdc]

Just send me an e-mail, and I will give you an address whenever you decide what you want to do.  My offer is open for a couple of months, don't know what the new year will bring as yet, may be moving to Fla. to get closer to my son and his family.  He retired from USAF, and my younger son is thinking of moving back to Fla, also.  Joe-JDC.

[rcodecj]

I plan on doing just that at Cecil dragstrip on the 29Th Barry. I find it hard to believe there is 50 hp there or even 30 hp. If it was a stock exhaust maybe, but 2 1/2 ID and Flowmasters shouldn't be that restrictive. I agree the Flows rant strait thru design but certainly not like the original cross flow. What is the muffler of choice for the street racer these days. While I was at the dyno there was a Corbra and it had spintechs definitely not getting those. I might as well have just pipe they crackle to much. Jay what cam would you recommend? Also the Streetmaster should support 640hp according to you guys so it  would be worth it to have JDC look at it I think. In the meantime I'm going to try and look at the back pressure scientifically before I go. I'm tired of hit or miss should be an easy test.

I had 3" magnaflows and to me they were too loud, couldn't talk to a person sitting in seat next to me going down the road.
I still have the magnaflows on the shelf.
Here's a sound video of the magnaflow:
http://s212.photobucket.com/albums/cc110/laveennick/?action=view&current=67mustang460manaflow3inchexhaust.mp4

I switched to Borla 3" and they were much quieter, perhaps because they actually only have a 2.5" core and a bit larger case.
Here's a sound video of the Borla:
http://s212.photobucket.com/albums/cc110/laveennick/?action=view&current=MOV01354.mp4

Magnaflow #14329:


Borla #40359:


Magnaflow and Borla side by side:

 

[sixty9cobra]

We will see what it does next week.

[rcodecj]

We will see what it does next week.

Cool. The dragstrip knows all, tells all.