Author Topic: Exhaust Advice Needed  (Read 2079 times)

HawkX66

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Re: Exhaust Advice Needed
« Reply #30 on: March 22, 2018, 05:45:06 PM »
Video clips aren't working for me for some reason.
Same for everyone else? I just made them public, so maybe that will help. I don't have to do that with regular pics.
Dave
69 SS396 X66 L34 M21 BS
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bcmiller

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Re: Exhaust Advice Needed
« Reply #31 on: March 22, 2018, 06:53:04 PM »
Video clips aren't working for me for some reason.

I ran both the American Thunder and the Force II FLowmaster transverse systems.   The American Thunder was hella loud with a ton of interior drone, after 6 months of daily driving I removed it. Switched to the Force II.   The Force II was more mellow, but oddly enough Flowmaster discontinued that system a few years back.

I ran both on my Formula, still have the systems stashed away.  I eventually switched my Formula to the same system I have on the Z I posted above.  I wanted the "X" cross over instead of the "H" was one reason for the change, and I wanted a stainless system was the other reason.  Plus the Pypes transverse muffler is touted as a straight through design and worth a little HP over the baffle/deflector style.  I was looking for a little edge in the Pure Stock racing category.

  Here is my Formula, setup to run Pure Stock with it's original 400 RAIII, running stock RA manifolds and the same Pypes 2 1/2" system.

https://youtu.be/er1z7PpqsnY     

Not only did the car pick up about 2 tenths with this system over the others, but it's also a very mellow sound, no drone in the car, very quiet to cruise down the road in.

Here's a ride along to get an idea how quiet it is inside the car.  Matter of fact, it's so quiet inside, I could hardly hear my car at all with the "open header" car next to me.  So much so that I quit looking at the tach for a few seconds and didn't even realize I had run 2nd gear out to 5700....Oooops.  It runs best shifting around 5200.

https://youtu.be/bpFwscg7uoY   

5200? I shifted my old TransAm 400 4 speed at 6100. :)

Even my current “old school 468” with 4 inch stroke occasionally gets above 6k.  :)

Don’t they at least let you run better valve springs???

Bryon / 1968 Camaro SS 396 - now 468 ci, M21, 12 bolt
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X33RS

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Re: Exhaust Advice Needed
« Reply #32 on: March 22, 2018, 06:57:00 PM »
Video clips aren't working for me for some reason.
Same for everyone else? I just made them public, so maybe that will help. I don't have to do that with regular pics.

Okay working for me now, thanks.

Sounds pretty good, fairly mellow.

X33RS

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Re: Exhaust Advice Needed
« Reply #33 on: March 22, 2018, 07:07:08 PM »
Video clips aren't working for me for some reason.

I ran both the American Thunder and the Force II FLowmaster transverse systems.   The American Thunder was hella loud with a ton of interior drone, after 6 months of daily driving I removed it. Switched to the Force II.   The Force II was more mellow, but oddly enough Flowmaster discontinued that system a few years back.

I ran both on my Formula, still have the systems stashed away.  I eventually switched my Formula to the same system I have on the Z I posted above.  I wanted the "X" cross over instead of the "H" was one reason for the change, and I wanted a stainless system was the other reason.  Plus the Pypes transverse muffler is touted as a straight through design and worth a little HP over the baffle/deflector style.  I was looking for a little edge in the Pure Stock racing category.

  Here is my Formula, setup to run Pure Stock with it's original 400 RAIII, running stock RA manifolds and the same Pypes 2 1/2" system.

https://youtu.be/er1z7PpqsnY     

Not only did the car pick up about 2 tenths with this system over the others, but it's also a very mellow sound, no drone in the car, very quiet to cruise down the road in.

Here's a ride along to get an idea how quiet it is inside the car.  Matter of fact, it's so quiet inside, I could hardly hear my car at all with the "open header" car next to me.  So much so that I quit looking at the tach for a few seconds and didn't even realize I had run 2nd gear out to 5700....Oooops.  It runs best shifting around 5200.

https://youtu.be/bpFwscg7uoY   

5200? I shifted my old TransAm 400 4 speed at 6100. :)

Even my current “old school 468” with 4 inch stroke occasionally gets above 6k.  :)

Don’t they at least let you run better valve springs???



They limit valve spring seat pressure to 130 lbs.    Which is plenty on a stock flat tappet to spin it up.  5700 doesn't hurt the engine and it runs fine up there, the car just doesn't go any quicker.   One big reason is because I have the factory cam advanced (installed on a 106 ICL) for a little more bottom end.  I did that because I only run a 3.31 gear in the car.  And that gear is in there because it's also a driver for us.  Cam is just the stock RAIII 212/225 @ .050 and .407 lift.

If I had my way the car would run best with a 3.73-ish gear, and then I'd probably move the cam out to a 109 ICL to shift the power up a bit and adjust shift points accordingly.  So there is more ET in it, I'm just not exploiting it.     However the quickest of the RAIII 400's in the class all pretty much run 3.73-3.90 gear and are right at high 12's and 107-108 mph on a good day.  Mine corrects to a 12.78 at 106 so I'm just about on par, without the rear gear.  So pretty happy with it actually.

X33RS

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Re: Exhaust Advice Needed
« Reply #34 on: March 22, 2018, 08:40:31 PM »
A good example of that  is our Z I posted above.  I built that engine with the same rules in mind in hopes of participating with that car.  Even with the valve spring limit, it still made peak power at 6700 rpm, I shifted in that video at 7,000.  I installed that cam only 2 degrees advance, wanted to make sure it made power up stares where these engines shine anyway, plus the stock camshaft is very healthy for a little 302 with 254 @ .050.   SBC has lighter valve train components than a Pontiac so that helps too.  For this car to run it's best it needs a bunch of gear.  Complete opposite end of the spectrum than the Pontiac.