At what RPM was that extra power extracted? Had to be at a much higher rpm since the larger diameter would lower velocity at a low rpm. My 390 engine will never ever see an rpm higher than 4000 in it's life. So what I would gain at the 5000 mark doesn't do me any good. Believe me I have played with the numbers on a dyno program and the only thing that consistently shows a decent power gain throughout the entire rpm range of the engine was headers besides a camshaft for my prime 1500-3000 rpm operating range.

There is lots of ideas on the H pipe but in real life probably doesn't do much for the street engine at all. I only did it in the Dodge because that is how Ford did it so I made an assumption. If I had known that was not how Mopar did it then I would have left it out.

 

The scoring system uses the average power over an rpm range. That testing range was 2300-5500. Since the average increased, that means power would have been better from 2300-5500. If you would like specifics, feel free to contact Ted. He shares that info openly.

Keep in mind also, this all was performed on an actual dyno, with real numbers being produced, not a program which can only estimate and may not be able to consider all variables in that estimation.

And sure, maybe that extra couple hp isn't worth it to you but to someone else, it is, and that's the reason we share info.

 

Well took it out for a spin tonite and tried to have an objective ear about it.

Seems to me it's just plain loud - there just ain't much in the way of soundproofing at all in these things to begin with. Have new radial tires, those alone are a good chunk of the noise and the rest of just general stuff, wind and vibration. Conversation wouldn't be too bad till around 50 mph but then it just gets louder and louder as speed increases.

Maybe not so much a resonance, but it's just loud-o-plenty at 65 to 70. Really have to shoot some video. Not too good at that uploading stuff. Pushed it up to steady cruise around 80 and it really runs great, can tell it's tuned good because it's so smooth, but wonder if might be more effective to just install more soundproofing in the doors and cab sides, roof etc.

The old Y block single exhaust with the crossover pipe had more of an engine braking effect on deceleration, it must have been fairly restrictive, that's gone now of course. Was sort if hoping to get some snap crackle and pop going on during deceleration.

Have to check the plugs, but at 70 mph pulling the choke out all the way doesn't seem to have any effect at all. That's too lean ain't it??

Kind of looked what's what after return, the driver side steel pac muffler has a big splotch of the enamel discolored due to heat, the passenger side not so much. Is this an indication of some kind of a over rich condition or mismatch something in that bank of cylinders?

 

After 30 posts later, go back and read #2. You are right, our 50 year old trucks were built much different from todays trucks. Now it has many places for the wind to come in, no sound dampening.

Sit on here and complain or git outside and start working on it.


John

 

Just happened to be watching one of the 900 car building shows on TV the other night and they were building an exhaust system. The Borla factory rep was there and said something interesting. When they were picking where they wanted the mufflers he said that they needed to be as far to the rear as was practical to keep them from resonating.
Did you get your "H" pipe in? If so did it help?

 

Naw, not yet...

 

I have to agree. In my opinion Borla are at the top of the food chain IMO. Also, my cross over is pretty close after the collectors and the muffs are just before the spare tire. 3 inch to 2.5 at the collector - 3" in / 3" out muffs with drop downs at muffs, 2.5" out the back.
3" in and out the muffs to allow for slow down inside the muffs.
Course, I'm just an old fart and most likely don't know what the hell I'm talking about. :-))

 

Kind of want to install something with maybe a slide, or a damper assembly maybe, like on a stovepipe. That way I could try both?