#21  
Old 03-17-2022, 03:53 PM
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Originally Posted by 77 TRASHCAN View Post
Not sure a Perf RPM Would fit under the hood of your TA.......
The Performer RPM intake won't fit unless a drop base unit is installed. That is what I had to do with my'78.

Here is a pix of the under hood before I had the v-belts removed and a march pulley system installed.
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  #22  
Old 03-17-2022, 04:21 PM
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A "massaged" Shaker base to clear Holley fuel bowls and a T2 will fit with a Shaker.
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1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
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  #23  
Old 03-17-2022, 04:38 PM
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Originally Posted by Skip Fix View Post
A "massaged" Shaker base to clear Holley fuel bowls and a T2 will fit with a Shaker.
Had to massage as well on my '70 with a RA IV repro intake to clear the holley street avenger 770.


Last edited by napster; 03-17-2022 at 04:54 PM.
  #24  
Old 03-17-2022, 05:37 PM
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Originally Posted by jhein View Post
I haven't pulled the intake off and looked at it but I would be quite surprised if it has had any work done to it, and I'm not planning any. From Cliff's previous comments on intakes and carbs I don't see the intake and carb holding me back. I think my motor will be limited by the 1.5 rockers, unported heads and the manifolds/exhaust.

But again, my goal is not maximum power. I just want more than stock power with a rock solid rotating assembly and valve train. I realize I'm getting very close, if not past, driveline parts breaking territory. But, I think with street tires and my driving style I'll probably be OK.
Unless you've already paid for parts, you might consider maximizing the combination as is. Especially if your driving style isn't hard on parts.

I did the same thing, and am now in a position that wanting more power means spending more on parts than had I just purchased what was best at the time.

Things like rockers don't change in cost across a 1.5 to 1.65 ratio, nor do the springs. But if you decide later on to change these things, you end up paying double, plus your time and labor.

At least something to think about.

My prediction for power would be in the 520hp/580 ft lbs range. I think the manifolds would work a bit better with a cam on a wider LSA. That said, this combo with an intake and header change down the road would likely pick up a good bit of power, even without a change in valvetrain package.

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Old 03-17-2022, 08:49 PM
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Is there such a thing as porting and/or polishing exhaust manifolds? Also right now I have a 2 1/4" exhaust system. Looks like a Gardner system but I'm not sure. I'm probably going to put a 2.5" Pypes system on it. Even if I gt headers (which I really don't want to do) I'd still need to upgrade the exhaust.

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https://youtube.com/shorts/gG15nb4FWeo?feature=share
  #26  
Old 03-17-2022, 09:21 PM
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Originally Posted by jhein View Post
Is there such a thing as porting and/or polishing exhaust manifolds? Also right now I have a 2 1/4" exhaust system. Looks like a Gardner system but I'm not sure. I'm probably going to put a 2.5" Pypes system on it. Even if I gt headers (which I really don't want to do) I'd still need to upgrade the exhaust.
Are you using the original RA III exhaust manifolds? If you are maybe move up to the 2.5 inch oversized manifolds you can get an additional 13% flow. In addition, are you going X-pipe with transverse muffler? Transverse is a bottle neck, that is why I went with two mufflers.

Here is how my '70 sounds like with the RA IV oversized manifolds and 2.5 inch mandrel bent pipes extensions from Pypes into a Flow Master American Thunder system with mandrel bent 2.5 inch pipes and H-pipe. Finally, Texas TA mufflers.

https://youtu.be/AXveB8zehOw

https://youtu.be/IsmQXWoIMSU

Don't know what sound you are looking for, but it might float your boat.

If you want more power, go with the X-pipe for the better scavenging effect. If you want the sound go with H-pipe. I don't race so I go with sound.


Last edited by napster; 03-17-2022 at 09:36 PM.
  #27  
Old 03-18-2022, 07:10 AM
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The big 455's will absolutely LOVE a 3" head pipe system, X or H and 3" straight thru mufflers. We've moved from 2.5" to 3" on several cars we drive and race here with nice improvements at the track every single time. The "H" is what I use and prefer and it really helps with cancelling out any resonance or "tinny" sounds you often hear with other systems at specific speed/engine RPM's.

At these bigger power levels a set of Ram Air manifolds and 2.5" mandrel bent exhaust with an X or H and straight thru mufflers is the absolute minimum and you are leaving some vehicle performance on the table compared to a good set of headers and larger less restrictive system.

Also be aware that moving to a "drop-base" air cleaner after installing a taller intake or spacers can cancel out more power than you ever hoped to make. You need a minimum of 3" from the top of the carb to the bottom of the air cleaner lid or there may be considerable power loss from that modification.

I'd also add that right on the dyno my modified stock iron intake made 6 more HP than an Edelbrock Performer RPM intake. A modified HO "re-pop" was 4 hp less than the RPM and it was also "modified" same as my iron intake. The test engine was a 440cid (428 based) with 260cfm KRE aluminum "D" ports, Oliver rods, Ross flat tops, 10.6 to 1 compression and custom ground HR cam with Comp XFI lobes (.361") sporting 236/242 @ .050" duration (topped with Crower Enduro 1.6 rockers). It made 497hp with the iron intake, 491hp with the RPM, and dropped to 487hp with the HO intake..........Cliff

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Old 03-18-2022, 08:16 AM
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I run a Torker 2 on my 76 Trans am. I made a few adjustments and it fits pretty good.

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  #29  
Old 03-18-2022, 11:06 AM
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Quote:
Originally Posted by napster View Post
Are you using the original RA III exhaust manifolds? If you are maybe move up to the 2.5 inch oversized manifolds you can get an additional 13% flow. In addition, are you going X-pipe with transverse muffler? Transverse is a bottle neck, that is why I went with two mufflers.

Here is how my '70 sounds like with the RA IV oversized manifolds and 2.5 inch mandrel bent pipes extensions from Pypes into a Flow Master American Thunder system with mandrel bent 2.5 inch pipes and H-pipe. Finally, Texas TA mufflers.

https://youtu.be/AXveB8zehOw

https://youtu.be/IsmQXWoIMSU

Don't know what sound you are looking for, but it might float your boat.

If you want more power, go with the X-pipe for the better scavenging effect. If you want the sound go with H-pipe. I don't race so I go with sound.
Are your tips the Pypes tips? And are they the long or short tips?

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https://youtube.com/shorts/gG15nb4FWeo?feature=share
  #30  
Old 03-18-2022, 11:37 AM
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Are your tips the Pypes tips? And are they the long or short tips?
They are the tips that are part of the system. 2.5 inch polished stainless steel tips. Angle cut is 45 degrees.

Here is a link to the system.
https://www.holley.com/products/exha...er/parts/17149

It comes with 50 series mufflers, but you can ditch them for others if you want like I did.

Hope it helps.


Last edited by napster; 03-18-2022 at 12:04 PM.
  #31  
Old 03-18-2022, 12:36 PM
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Not going to make over 500 with 2.25" manifolds.

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1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
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1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
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Old 03-18-2022, 03:05 PM
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Originally Posted by Skip Fix View Post
Not going to make over 500 with 2.25" manifolds.
I didn't know that the RA restorations manifolds were available in 2.5" size. They aren't available now, maybe June, according to them. So it seems like I would want a set of those plus a new 2.5" mandrel bent exhaust. Since I won't be able to get the manifolds in time, I'm just going to run it through what I have now and see how it feels. We're all talking about numbers here but I really don't care much about that. I'm not racing so I don't care about time slips and I won't compete with anyone on the highest Dyno numbers so none of that matters to me. I only care how it feels when I drive it. If it feels like it's choked out then I can always upgrade later. If it feels great and runs great, maybe I'll leave it.

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https://youtube.com/shorts/gG15nb4FWeo?feature=share
  #33  
Old 03-18-2022, 03:10 PM
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The 2.5s are the 2.25s just opened up at the opening. It does make the sealing lip a lot thinner I had some sealing issues ion the D port ones on my 81.

It will still have GOBS of TQ and HP even with the intake and exhaust.

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1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
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  #34  
Old 03-18-2022, 07:26 PM
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jhien,

Here are a few pixs.
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  #35  
Old 03-18-2022, 07:29 PM
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Here are three more. There are more, but that can be done through email. Also, I don't have the bolts or clamps. Got lost in moves from storage facilties.
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Last edited by napster; 03-18-2022 at 07:36 PM.
  #36  
Old 03-20-2022, 05:50 PM
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Quote:
Originally Posted by jhein View Post
I didn't know that the RA restorations manifolds were available in 2.5" size. They aren't available now, maybe June, according to them. So it seems like I would want a set of those plus a new 2.5" mandrel bent exhaust. Since I won't be able to get the manifolds in time, I'm just going to run it through what I have now and see how it feels. We're all talking about numbers here but I really don't care much about that. I'm not racing so I don't care about time slips and I won't compete with anyone on the highest Dyno numbers so none of that matters to me. I only care how it feels when I drive it. If it feels like it's choked out then I can always upgrade later. If it feels great and runs great, maybe I'll leave it.
Jhein, I bought a '70 Tempest a few years ago that had a nicely built 461 (.030" over 400 with a 4.25" stroke), SD Perf ported 6X-8 heads (250 cfm intakes/ 200 cfm exhausts/9.5 compression) with the standard 2.2" outlet RA manifolds tied into 2.5" mandrel X-pipe exhaust system, RPM intake with a Holley 850, and a HFT Bullet RAIV-style cam (231/239/112 @ .480" lift) with 1.5 roller rockers. That car ran 11.90's @ 115 mph on drag radials, 3.42 gears and a tight 'Jim Hand' Continental 10" torque convertor in a TH400. It weighed just under 3700 lbs race weight. So, a well built 455/461 can run pretty well with the smaller outlet RA manifolds. It would probably run 11.80's with the bigger 2.5" manifolds and 11.50 with good headers and a 3" exhaust pipes/mufflers to 2.5" tailpipes.

I'm not sure what hp that equates to, especially the 116 mph pass.

Dennis
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Last edited by SD455DJ; 03-20-2022 at 06:11 PM.
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  #37  
Old 03-20-2022, 08:25 PM
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Quote:
Originally Posted by SD455DJ View Post
Jhein, I bought a '70 Tempest a few years ago that had a nicely built 461 (.030" over 400 with a 4.25" stroke), SD Perf ported 6X-8 heads (250 cfm intakes/ 200 cfm exhausts/9.5 compression) with the standard 2.2" outlet RA manifolds tied into 2.5" mandrel X-pipe exhaust system, RPM intake with a Holley 850, and a HFT Bullet RAIV-style cam (231/239/112 @ .480" lift) with 1.5 roller rockers. That car ran 11.90's @ 115 mph on drag radials, 3.42 gears and a tight 'Jim Hand' Continental 10" torque convertor in a TH400. It weighed just under 3700 lbs race weight. So, a well built 455/461 can run pretty well with the smaller outlet RA manifolds. It would probably run 11.80's with the bigger 2.5" manifolds and 11.50 with good headers and a 3" exhaust pipes/mufflers to 2.5" tailpipes.

I'm not sure what hp that equates to, especially the 116 mph pass.

Dennis
Interesting. Just out of curiosity, what do you think it would do with a 2.25 exhaust system?

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https://youtube.com/shorts/gG15nb4FWeo?feature=share
  #38  
Old 03-21-2022, 07:28 AM
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Originally Posted by jhein View Post
Interesting. Just out of curiosity, what do you think it would do with a 2.25 exhaust system?
That would choke that size engine too much above 2500 rpm at full throttle. We discovered at the pure stock drags that the mandrel bent 2.5" exhaust systems from the manifolds (log & RA) to at least the tailpipes would greatly add to the power band for Pontiac 400's/455's of all stripes and reduce et's by .2 to .3 seconds (or more!) and add a 2-4 mph. So they are totally worth installing. The Pypes 2nd gen Firebird system with, or without, the X-pipe and the Race Pro transverse muffler is a great system. It does need tweaking to make it fit right (a little cutting and welding), but it's not leaving much on the table for a 450 hp engine with RA manifolds. If you are wanting 500+ HP, go with the 2.5" outlet manifolds and at least 3" headpipes/X-pipes to the mufflers.

Dennis

  #39  
Old 03-21-2022, 08:23 AM
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My iron headed and iron intake 455 made 491/570 trq with 1.75 headers and lost about 17hp with the 2.25 ra manifolds with mandrel 2.5 headpipes. I did try to massage the outlet size on the exhaust manifolds with a electric grinder some. I bought my aftermarket manifolds many years ago,even maybe when they were first introduced. I ground as much as I dared to but still not out to 2.45"

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Old 03-21-2022, 12:52 PM
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Quote:
Originally Posted by scott70 View Post
My iron headed and iron intake 455 made 491/570 trq with 1.75 headers and lost about 17hp with the 2.25 ra manifolds with mandrel 2.5 headpipes. I did try to massage the outlet size on the exhaust manifolds with a electric grinder some. I bought my aftermarket manifolds many years ago,even maybe when they were first introduced. I ground as much as I dared to but still not out to 2.45"
Scott70, Those are great numbers and minimal losses going to RA manifolds from the headers. Do you have the Dyno printouts for the two? It would be interesting to see when (rpm) the power dropped.

Dennis

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