#21  
Old 07-26-2021, 05:59 AM
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"i ran a t2 with a 1 inch open spacer on my 65 gto, then decided to try an rpm. then decided to try the spacer on the rpm. now i have a tiny little dent in my hood from the air cleaner stud. i need a good reminder that i am stupid every now and again, and that dent is in the perfect spot to remind me pretty often"...

I did that once about 40 years ago. Was helping a friend with his 1967 Chevy II Nova and we just installed a high rise intake and aftermarket carb. Ya, I did some of that stupid chit back in those days before I figured out it was all just bling.

The new shiny parts looked so cool under the hood we were in a big hurry for a test ride. I slammed the hood down, darned thing wouldn't close...WTF? So I slammed it harder and just about got it close with a little extra help from all my weight on the front of it.

I looked up then to see a really nice big dimple in the center of the hood....OOOPS!....

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73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
  #22  
Old 07-26-2021, 06:06 AM
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"so far everytime i have tried spacers on a rpm the engine responded very very well (both 400 and 455), open spacers has worked great for me."

Some engines hate it when one side of a dual plane intake sees too much of the other. I've had to make dividers for my RPM intakes than I can count for that reason. Cutting them down will show a nice power increase upper mid-range and top end, but it may induce a "stumble" going from idle to full throttle that is difficult to tune out because lots of these engines woln't have superior power to weight or pretty tight converters in them.

I'd also add here that at the 500hp mark the RPM brings NOTHING to the table over a stock intake and just barely more power than an factory reproduction HO unit.

I did that testing a while back on a 440cid engine (428) we built here. KRE heads prepared here, Comp 236/242 HR (XFI lobes) cam, Ross pistons, Oliver rods, 10.6 to 1 compression. With my stock intake (sorry folks it's modified a little) it made 497hp/540tq. Installed the RPM with no other changes and it dropped to 491hp, Installed the HO intake and it dropped to 487hp.

When you read that think about how many folks run out and buy RPM intakes to replace stock ones on mild 350 and 400 engines. Then they have to put a drop base air cleaner in place to get the hood closed and loose another 20-30hp!.......FWIW......

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  #23  
Old 07-26-2021, 07:09 AM
Steve C. Steve C. is offline
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Dave Bisschop intake dyno testing....

474ci engine / 290cfm CNC ported KRE D-port heads with 10.2 to 1 compression on 91 octane fuel with a 236/245 duration hyd. roller cam.

Intakes gasket matched to a 1233 Felpro gasket, each intake was mocked up to make sure port alignment was correct and each intake had the water crossover removed.

Stock iron factory intake with Q-jet carb.
515hp @ 52-5300rpm and 575 lb/ft @ 4000 rpm.

Factory cast iron with the CNC machined plenum with Q-jet carb.
527hp @ 5300rpm and 579 lb ft @ 4100rpm.

Edelbrock Performer RPM
541hp @ 5400 rpm and 591 lb ft @ 4000 rpm.

"The purpose of this test was to see how each intake behaved in this particular engine combination. Other combo's can and will have different results but I felt this info would be interesting to our customers to look at and may be helpful in parts selection"
Dave Bisschop


.

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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 )
Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/

Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine)
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  #24  
Old 07-26-2021, 07:22 AM
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Quote:
Originally Posted by Cliff R View Post
"so far everytime i have tried spacers on a rpm the engine responded very very well (both 400 and 455), open spacers has worked great for me."

Some engines hate it when one side of a dual plane intake sees too much of the other. I've had to make dividers for my RPM intakes than I can count for that reason. Cutting them down will show a nice power increase upper mid-range and top end, but it may induce a "stumble" going from idle to full throttle that is difficult to tune out because lots of these engines woln't have superior power to weight or pretty tight converters in them.

I'd also add here that at the 500hp mark the RPM brings NOTHING to the table over a stock intake and just barely more power than an factory reproduction HO unit.

I did that testing a while back on a 440cid engine (428) we built here. KRE heads prepared here, Comp 236/242 HR (XFI lobes) cam, Ross pistons, Oliver rods, 10.6 to 1 compression. With my stock intake (sorry folks it's modified a little) it made 497hp/540tq. Installed the RPM with no other changes and it dropped to 491hp, Installed the HO intake and it dropped to 487hp.

When you read that think about how many folks run out and buy RPM intakes to replace stock ones on mild 350 and 400 engines. Then they have to put a drop base air cleaner in place to get the hood closed and loose another 20-30hp!.......FWIW......
I have done tons of track testing with spacers on our 400 in our 73 Ventura, open spacers are worth a tenth (slightly more actually). Every car presents it's own issues, people need to test and modify as they see fit. Based on my experience (track and dyno) the rpm really likes spacers.

  #25  
Old 07-26-2021, 07:23 AM
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Quote:
Originally Posted by Steve C. View Post
Dave Bisschop intake dyno testing....

474ci engine / 290cfm CNC ported KRE D-port heads with 10.2 to 1 compression on 91 octane fuel with a 236/245 duration hyd. roller cam.

Intakes gasket matched to a 1233 Felpro gasket, each intake was mocked up to make sure port alignment was correct and each intake had the water crossover removed.

Stock iron factory intake with Q-jet carb.
515hp @ 52-5300rpm and 575 lb/ft @ 4000 rpm.

Factory cast iron with the CNC machined plenum with Q-jet carb.
527hp @ 5300rpm and 579 lb ft @ 4100rpm.

Edelbrock Performer RPM
541hp @ 5400 rpm and 591 lb ft @ 4000 rpm.

"The purpose of this test was to see how each intake behaved in this particular engine combination. Other combo's can and will have different results but I felt this info would be interesting to our customers to look at and may be helpful in parts selection"
Dave Bisschop


.
Cool test!

  #26  
Old 07-26-2021, 07:30 AM
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With and without spacer (disregard first couple hundred rpm the "drip" is dyno operator rolling into throttle still)
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  #27  
Old 07-26-2021, 07:38 AM
Steve C. Steve C. is offline
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455 based engine built by Ken Crocie

Edelbrock cylinder heads, about 288 cfm at .600" lift / 10.2 compression.
Valvespring pressure 130 on the seat, with 320 pounds open pressure.
1.800" installed height.
Comp Cams 320H hydraulic flat tappet cam.
Rhodes Vari-Duration lifters.
Harland Sharp 1.65 rocker arms.
0.606" net lift at the valve.
Headers.

Two intakes dyno tested. Results here with a 850-cfm Holley carb

Torker II intake with 2-inch carb spacer- 570 hp at 5900 rpm with 573 ft.lbs. at 4300 rpm.

Performer RPM intake- 572 hp at 5900 rpm with 582 ft.lbs. at 4400 rpm.


.

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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 )
Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/

Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine)
5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE
  #28  
Old 07-26-2021, 07:49 AM
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We had a higher end 455 on the dyno (well over 600hp) once with a ported Tomahawk intake on it. It was using CNC ported KRE heads and a "hefty" solid roller cam. So more of a "max-effort" engine but he still wanted it to fit under the stock hood and use the stock Q-jet carb and factory Ram Air components so no spacer.

The engine wasn't doing well on the dyno so we installed a Victor/Dominator to see if there was something going on with the intake and carb.

The next pull netted 102 more HP than the last pull with the Tomahawk and Q-jet......YIKES!

In the interim between pulls we fabricated a 1" spacer to blend the Q-jet to the Tomahawk intake. The spacer was very well done and nicely blended the flow from the carb to the plenum area. Put that intake back on and made within 10hp of HP of the Victor/Dominator!

An early lesson in this deal about how some combinations of parts don't work all that well.

Steve NEVER resists an opportunity to throw Dave Bishops test in my face since he was using a CNC pattern of my iron intake. I guess there is a crossover point between my iron intake working better than or not as good as an RPM.

It's the same chit as WAY back when Jim Hand went to Ark City with a big Holley carb and ran some of the best times his Wagon ever saw. Folks threw that in my face for years, even after Jim went back to the stock intake, Q-jet, and ran better numbers and didn't have the "mine-shaft" air and perfect track conditions they had at Ark City for that race. It just goes with the territory and after doing this now for over 40 years I'm used to it and understand the propaganda associated with aftermarket "high performance" parts. When I outrun them on the dyno or at the track there will not be much mention of it. Get outran by one of those parts and you'll here about it hundreds of times for years to come!....LOL

Anyhow, at the 500hp mark on a very well prepared 428 build the RPM brought nothing to the table, so at some point the RPM may be better than a stock intake, but it's unlikely it does anything for 90 percent of the Pontiac street engines it ends up on, and probably quite a bit less after the drop base air cleaners and other "cobbling" required to install it.

I ran an RPM for about 6 years on my last 455, had to ditch the factory Shaker top and get a shorter one only to find out that it HATED the factory air cleaner lid being moved 1" closer to the carb. I briefly tried the K & N Xtreme lid but it hated that too, so I had to fabricate a custom air filter and shoved it in the Shaker opening. It was all good after the cobbling and I ran over 120,mph at Norwalk on the first outing. Before I could bust into the 10's with it they shut me down and we had to retard the timing 4 degrees, put two cylinder heads in the trunk and short shift at 5000rpm's to keep the track officials happy.

A few years later I decided to return the car to street duty and put the iron intake back in place with the stock Shaker and factory air cleaner assembly. I also put an electric choke back on the carb, and full length mandrel bent tail pipes. I figured it would slow the car down some but was way under the roll bar rule anyhow and not planning on installing one.

To my surprise the car went quicker in ET on the first outing to our local 1/8th mile track at about the same MPH! So much for slowing it down. I typically ran bottom 7's around 95-97mph with the RPM. Most runs would be in the 7.20-7.35 range depending on DA and track conditions. I managed a 7.18 with the stock intake and Shaker parts in pretty hot/humid weather!...... FWIW.......Cliff

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73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),

Last edited by Cliff R; 07-26-2021 at 08:41 AM.
  #29  
Old 07-26-2021, 10:17 AM
Steve C. Steve C. is offline
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Cliff, no intention to throw Dave Bishops test in your face. Posted for general interest here.
I spaced the link. My apologies for not adding it where he notes the intake had CNC machined plenum copied from Cliff's personal intake.


http://www.sdperformance.com/newsStory.php?newsID=44


.

__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 )
Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/

Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine)
5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE
  #30  
Old 07-26-2021, 01:50 PM
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RocktimusPryme RocktimusPryme is offline
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Just for informational purposes I chose an RPM for my engine based specifically on that SD test that was linked. At the time I thought that engine was very similar to where mine would be so it seemed a good match. Ultimately my mill made a little more power. Probably because I have a little more head flow and my RPM was ported a little. I dont know exactly what, I bought it used off this board. The Ad said "Ported to match 300 CFM heads" I think the divider is notched but its been forever since I actually looked at it.

I generally feel like you can choose an RPM across any brand with a 300-550ish HP motor and feel very confident you didnt make a bad choice. Thats not to say its the best everytime, but its just damn consistent good. I think you can probably say the same about SD worked cast Pontiac intakes.

Now with all that said, if I had to do it over again, I think I would go for a single plane in my case. It seems like some of the old stigma that single plane intakes "make more numbers up top but give up too much down low" may be antiquated. Again, with a 500ish HP modern efficient headed build it seems like modern single planes like the VIctor Jr you dont give up as much meat in the middle as old conventional wisdom would dictate while making notable gains on the top end. Ive seen quite a few dyno sheets over the last few years to back this up, as well as episodes of Engine Masters etc.

Im not versed enough in Pontiac single planes to say what the Poncho version of the Victor Jr would be. I know the Torker II with a spacer has quite a following around here, where they are considered less useful by Brand X motors. Im not sure if thats the lack of availability of better single planes on Pontiac motors or if the Torker II Pontiac intake is flat out better than the Chevrolet version of the same intake.

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  #31  
Old 07-26-2021, 04:09 PM
Steve C. Steve C. is offline
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"Victor Jr." is the terminology for a Edelbrock Small Block Chevy intake manifold. For the Pontiac Edelbrock calls it the "Victor".
If interested, here is a nice article for a 4.250 stroke build that used the Victor intake... and certainly not lacking in the torque department.

"It carried over 530 lb-ft of torque for nearly the entire pull, and that should make for a great street engine that can be driven in any situation with little to no maintenance."

"This wasn't a 'dyno' combo, however, which might typically include borderline compression, a huge camshaft, and a large carburetor. Instead, we took a conservative approach based on the vehicle's intended use."

https://www.motortrend.com/how-to/hp...-engine-build/


.

__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 )
Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/

Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine)
5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE
  #32  
Old 07-26-2021, 05:20 PM
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RocktimusPryme RocktimusPryme is offline
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Good to know. But yeah thats exactly the type of dyno sheets Im talking about that I have been seeing.

FWIW they make the Victor Jr for BBCs too, its called the Victor Jr 454-R.

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  #33  
Old 07-26-2021, 08:15 PM
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My 450 hp combo picked up 7/7 with a 1" spacer.

  #34  
Old 07-26-2021, 11:46 PM
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Quote:
Originally Posted by Cliff R View Post
"i ran a t2 with a 1 inch open spacer on my 65 gto, then decided to try an rpm. then decided to try the spacer on the rpm. now i have a tiny little dent in my hood from the air cleaner stud. i need a good reminder that i am stupid every now and again, and that dent is in the perfect spot to remind me pretty often"...

I did that once about 40 years ago. Was helping a friend with his 1967 Chevy II Nova and we just installed a high rise intake and aftermarket carb. Ya, I did some of that stupid chit back in those days before I figured out it was all just bling.

The new shiny parts looked so cool under the hood we were in a big hurry for a test ride. I slammed the hood down, darned thing wouldn't close...WTF? So I slammed it harder and just about got it close with a little extra help from all my weight on the front of it.

I looked up then to see a really nice big dimple in the center of the hood....OOOPS!....
i keep thinking about going back to the t2 and spacer. seemed like it pulled maybe a smidge harder than the RPM, it’s a 505 with old faithful and a stick shift. but with the RPM intake it just tractors up the driveway in first gear at 1000 rpm which is nice, less likely to kick up gravel on the finish. i seem to remember the t2 and open spacer was just a little soggier off idle and took more finesse to get it up the driveway slowly.

funny, i started off thinking i was building a race car - aftermarket block, ported e-heads, electric fuel pump, solid roller, driveshaft loop and strange s60, electric fans, etc. since then i’ve gone back to a hyd roller and mechanical fuel pump, might swap out the fan for a mechanical as well. i probably would have been just as happy with a basic 389 four barrel stock hyd flat combo ... didn’t realize how tame i’d become in my 40’s!

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