[Formulajones]

https://forums.maxperformanceinc.com...ifolds+headers

Here is the thread that Paul started of an engine he built and dyno'd. Comparing 4 tube headers to the RA manifolds. Pretty impressive.

[vertigto]

Paul's results are pretty impressive. Can't see why you would go with headers over RARE manifolds. Has anyone done similar with stock logs vs. RARE manifolds (2.25 and/or 2.45)? That would be interesting to see across the powerband.

Also curious everyone's experience with the ceramic coating (3 yr. warranty) and if it's holding up or if it would have been better to forego the cost and apply/bake your own (read some threads about that)?

[Formulajones]

On more serious street builds, I go with headers. Dad's engine for instance, being a 571 and making over 700hp, I'm fairly sure taking the 2" Super Comps off and putting RA manifolds on that one would kill some serious power.

But I feel anything in the 500hp range, which fits most Pontiac builds, the RA manifolds are hard to beat.

On coatings, when it comes to exhaust manifolds, I like to use the POR 15 exhaust coating. Comes in a cast grey and that stuff seems to hold up. I did the RA manifolds on my bird about 4 years ago now, I daily drive it, and they still look like the day I coated them. I simply brush it on. A little pint can will do 3-4 sets of manifolds.

https://www.walmart.com/ip/POR-15-PO...gaAv5JEALw_wcB

[Skip Fix]

We swapped a set of 1 3/4- 1 7/8 step header in place for 2" on a 462 E head motor and lost 40 hp.

[Tempest T-37]

Originally Posted by SD455DJ

Tempest T-37 - That's an excellent alternative to the expensive stainless steel Pypes systems and your plan sounds great...so good that I'm going to look into the Thrush system for my GT-37 with the Pypes 2.5" headpipes and UltraFlo or Magnaflow mufflers.


Dennis

I'm not so sure how great of an idea it was after all, the kit arrived last Friday missing half of the components, so we'll see how Advance Auto handles it.

[Formulajones]

I've heard of that happening before. I think people buy the kits through their local auto store rather than use Jegs or Summit. Then they take what they want out of the kit and take it back for a return. No one checks the box and it somehow gets cycled back into circulation. It's a shame, not Thrush or Dynomax's fault.

I've had similar issues like that with other parts from the local parts stores where some pieces are missing. I've even seen the counter guys take stuff out of another box to make the customer happy. I'm not confident all of that stuff makes it back to the manufacture as a return. I believe they sometimes get tossed back onto the shelf for the next poor guy to purchase.

If you do happen to get a full kit, I don't think you'll be disappointed with it. One of my favorite transverse kits for F-bodies has been the 89021. Very inexpensive and nice sound and excellent fitment.

[SD455DJ]

Originally Posted by Tempest T-37

I'm not so sure how great of an idea it was after all, the kit arrived last Friday missing half of the components, so we'll see how Advance Auto handles it.

Let us know how that goes Tempest T-37. Sorry to hear about the incomplete system and I hope AA makes good on it.

Dennis

[Skip Fix]

I want to think also I saw an article with I think Pontiac engineers on an SD 455 dynoed with manifolds then headers and headers picked up a bunch also. Lee Atkinson dynoed his "plain" 455 Firebird with manifolds then tro ys and picked up a bunch.

[Tempest T-37]

Originally Posted by SD455DJ

Let us know how that goes Tempest T-37. Sorry to hear about the incomplete system and I hope AA makes good on it.

Dennis

Well, Advance Auto resolved the issue for me. They shipped a replacement kit and it seems to have everything in it. With that said, I'd order it through a brick and mortar and pick it up in a truck if that's an option. The packing job by Walker/Thrush is complete crap. Loose pipes and hangers and the bolts are in a small bag, and the mufflers are in small boxes. There's no foam/bubblewrap or anything to keep the stuff from demolishing the box in shipping.

[vertigto]

Gotta love the discounts Advance Auto is able to offer. The Labor Day promotion was 25% off pretty much everything...probably should have ordered the 2.5" Thrush kit.

https://shop.advanceautoparts.com/p/...rush%20exhaust

It looks pretty good and is stupid cheap...any drawbacks (aside from maybe replacing the mufflers)?

[Tempest T-37]

The only drawback I see, is it doesn't seem to be fully mandrel bent. The H-pipe piece seems to be, but the over axle pipes, tailpipes and header pipes all have decreased diameter in the bends. It's not extreme, and not as bad a pinch bend, but still a reduction. I'm not going to complain for the price though. The tailpipes are turn downs, so a different kit may be needed for GTO splitters (or possibly you could just cut the turn downs off)

[SD455DJ]

Tempest T-37 - Could you post pictures of the system and close-ups of the kinked bends? Thanks!!!

Dennis

['ol Pinion head]

Dennis, are you acquainted with an old article with Dyno tests comparing same engine with A-body RA manifolds & then Dport logs with a mandrel bent drop? May have also tested a pair of the "shorty" style headers that were once built for Dport heads...

[Tempest T-37]

The over axle tubes seem to be the only mandrel bent pieces


pre- h-pipe


h-pipe


The narrowest area I could find was 2.4" x 2.2" OD in the pre- h-pipe section. This kit was meant for headers, so there are header flange adapters as well. I'll be using logs and pypes down tubes

[SD455DJ]

Originally Posted by 'ol Pinion head

Dennis, are you acquainted with an old article with Dyno tests comparing same engine with A-body RA manifolds & then Dport logs with a mandrel bent drop? May have also tested a pair of the "shorty" style headers that were once built for Dport heads...

Roger, Yep, I sure do remember that articla. Dan authored that article for MuscleCar Review magazine back in the 90's (?) sometime. Dan rebuilt a numbers matching '69 RAIII from a '69 Trans Am (M20/3.55) that was a basic rebuild with .030 over forged TRW pistons on resized cast rods, stock #48 heads/intake/7029273 Q-jet, Crane 068 copy cam, and long branch exhaust manifolds. I recall the static compression landed around the 10.3 to 1 range. It was one of his first Pure Stock builds and thought it was a mild enough rebuild to test the variety of factory manifolds in '69...logs, A-body RA manifolds, and the F/B body long branches. I don't have the results in front of me, but I recall the long branches made 3-4 hp/lbft more than the RA manifolds and only 7-8 hp/lb/ft over the F-body logs, both over the entire rpm range of the dyno pulls. I can't recall if he had the mandrel bent headpipes for the logs or not. I'm sure I'm mistaken on the actual numbers, but there was an incremental step in power from the logs to the RA's to the LB's.

The take-away was that a fairly mild smaller (400 ci) engine isn't affected too greatly by the exhaust and the logs flowed better than expected. Logs do become a hinderance on a 455 with a RAIV cam however. I wish I had swapped RA manifolds onto the small valve 455 (9.9 compression & 2802 cam) we built with logs that made 390 hp/512 lbft torque. We believe that alone would have allowed 400 hp/520 lbft easily.

In the earlier days of the Pure Stock Drags there was a participant that had a '70 455 GTO that showed up with RA manifolds (not OK) and RA unit (OK). We told him he could run, but needed to change the RA manifolds back to logs if was coming back the following year. He ran mid-13's with the RA manifolds. The following year he had the logs back on and ran mid 13's...no change and he was shocked that he didn't loose performance. He shifted at 4800-5000 rpm and had an 068 style cam...very mild in that motor.

Dennis

[SD455DJ]

Tempest T-37 - Thanks for the great pictures. That system along with the Pypes 2.5" mandrel head pipes and Dynomax UltraFlo 18" mufflers would make a really nice free flowing system on a budget. By the time the exhaust gasses get to the transmission area they have cooled and condensed enough to not be bothered by the small compressions and bends in the pipe...behind a fairly mild engine anyway. I'd certainly use that set-up on my GT-37 with the 455HO.

Dennis

[vertigto]

Yep...ordered the Thrush system last night when I saw that Advance Auto was offering 25% off again for kits for a limited time . Not sure you can beat it for the $$ with mufflers, although I will be swapping them out.

Anyone looking for a pair of Thrush Turbos??

[vertigto]

Well...mine came in the mail today and the big box was tore up. Luckily it had everything except for one of the plates, otherwise all of the pipes, mufflers, fastners and hangers are there and not damaged. Customer Service says they'll try and get the plate from the depot before contacting Thrush...we'll see. Said I should know something @ 24 hours.