Edelbrock RPMII vs. Holley Systemax II
- Thread starter 90mustangGT
- Start date
I't about area under the whole curve - not just the low end. A professionally ported Performer will carry farther than 4,000 rpm on a 347. Try it. Just don't expect to use it above 6,000-6,500 rpm and make the best power - you need more cross section then.
A custom cam, within limits, can crutch a combo with some mismatch.
Rick's suggested intake will also make excellent power in a different area of the curve - a carb intake does not have the runner length restriction and EFI does and they give up some low end which is not an issue on a race car. May not ber an issue on the street either if you retain sufficient torque to move the car's weight off-idle.
Let me spell this out for some of you:
A 347 with a 290+ .006" duration cam that are going to spin a 347 above 6,500 RPM need a runner length that is approximately 12" in length with ~ a 2.6-2.7 sq.in cross section along with an 80mm TB. A Victor EFI would work well here.
A 347 with a 280- .006" duration cam that are going to spin a 347 no higher than 6,500 rpm need a runner length of approximately 14.5" with ~ a 2.4 sq.in cross section and a 75mm TB. A ported Performer fits this bill perfectly.
A custom cam, within limits, can crutch a combo with some mismatch.
Rick's suggested intake will also make excellent power in a different area of the curve - a carb intake does not have the runner length restriction and EFI does and they give up some low end which is not an issue on a race car. May not ber an issue on the street either if you retain sufficient torque to move the car's weight off-idle.
Let me spell this out for some of you:
A 347 with a 290+ .006" duration cam that are going to spin a 347 above 6,500 RPM need a runner length that is approximately 12" in length with ~ a 2.6-2.7 sq.in cross section along with an 80mm TB. A Victor EFI would work well here.
A 347 with a 280- .006" duration cam that are going to spin a 347 no higher than 6,500 rpm need a runner length of approximately 14.5" with ~ a 2.4 sq.in cross section and a 75mm TB. A ported Performer fits this bill perfectly.
blackstangt
Member
90mustangGT said:
Blocks are easy to come by, try getting a roller block, also, the typhoon intake is supposed to be exactly the same as the performer rpm, so it would be a step up, and you can get it for like 300. I have it and besides timing difficulty and lack of oil shield for the lower, it works perfectly... it way even be a little too high rpm for my setup(better for yours), but works really well.
tmoss said:
I just checked my cam card as I was worried I was gonna have to spend more money on an intake swap. My @.006" is 286/298 so look like my R intake is good for me. (not that I ever doubted my choice one bit)
Heres another graph I have on my pc of a 347 with TW heads, R manifold, 1 3/4" longtubes, 3" exhaust and a buddy rawls custom solid roller designed for low rpm torque. This graph does the opposite of what most would think with these "big" parts. Here it is:
At one time there was an rpm II vs systemax test in the cards...but someone sold the car in question that was to be used. 
I guess they never got anyone else to do it.
Jason
I guess they never got anyone else to do it.
Jason
Still bugs me the RPM II article claims a 306(not that it really matters, but it was just a polished crank, stock rods, and a set of standard bore DSS pistons)
No i didn't. Best pass was 1.54 60' and 11.65 @ 117mph. When i got to the track my tach decided to not work....and the stocker was of absolute no use anyways. No idea where i was shifting, but it was low...bogged. This was the blue coue. I wish i'd never sold either of those cars, it was fun when i had em both running.
The light gray coupe is floating around this board somewhere. I talk with the guy occasionaly, don't know if he posts much as i don't anymore.
In the process of building another...may go 347 this time with the N-111, tfs box upper..or just stick to the 302 with these parts also.
No i didn't. Best pass was 1.54 60' and 11.65 @ 117mph. When i got to the track my tach decided to not work....and the stocker was of absolute no use anyways. No idea where i was shifting, but it was low...bogged. This was the blue coue. I wish i'd never sold either of those cars, it was fun when i had em both running.
The light gray coupe is floating around this board somewhere. I talk with the guy occasionaly, don't know if he posts much as i don't anymore.
In the process of building another...may go 347 this time with the N-111, tfs box upper..or just stick to the 302 with these parts also.
Grn92LX said:
Those parts are not "big" for a 347 and so the graph depicts. Looks like they should/did work good together.
Well, the 306 vs. 347 is out of my mind. I just finished talking to Rick, the 347 rotating assembly is now in progress. Rick gave me a lot of usefull info and put my mind to ease. Maby I'll sleep tonight. 
I think I might just go with a carbed setup, BG demon series 750 on a Victor Jr. intake, of course a different fuel pump and such but I'll be selling my EFI stuff real soon.
Emailed back from thumper about the head work. Definatly will keep that in mind.
Really, the rest of the stuff I am going to worry about a little later.
I apreciate all the help everyone, it gave me a lot of insight. I've always wanted a badass car that can really run'em, and I know that I better do it now while I am young and don't have too many other responsibilities such as kids, a wife, morgage and such.
I think I might just go with a carbed setup, BG demon series 750 on a Victor Jr. intake, of course a different fuel pump and such but I'll be selling my EFI stuff real soon.
Emailed back from thumper about the head work. Definatly will keep that in mind.
Really, the rest of the stuff I am going to worry about a little later.
I apreciate all the help everyone, it gave me a lot of insight. I've always wanted a badass car that can really run'em, and I know that I better do it now while I am young and don't have too many other responsibilities such as kids, a wife, morgage and such.
Grn92LX said:Sounds like a badd ass machine manToo bad you're down south, would be fun to line up with ya.
Theres plenty of good places that can work those twisted wedges, I did my HW on that
What assembly did you go with?
I went the the same setup you have basically, The Scat 9000 crank, probe 5.315 (I think, not the 5.4) same pistons you have. I got the 28oz Poineer balancer and the Spec billet steel flywheel too. Rick is going to balance everything.
Looking up about twisted wedge porting, some good places out there no doubt. I will probally go with thumper because I was so impressed with what he did with E7's, and it wouldn't be his first pair.
Love to race, will travel, you never know.
90mustangGT said:I went the the same setup you have basically, The Scat 9000 crank, probe 5.315 (I think, not the 5.4) same pistons you have. I got the 28oz Poineer balancer and the Spec billet steel flywheel too. Rick is going to balance everything.
Looking up about twisted wedge porting, some good places out there no doubt. I will probally go with thumper because I was so impressed with what he did with E7's, and it wouldn't be his first pair.
Love to race, will travel, you never know.
I went with the 5.315" probe ultralight I beams. I wanted the 5.4" but Rick said they were on a long ass backorder so I went 5.315". I went with an aluminum flywheel too and a light weight romac balancer. I really like light weight rotating stuff.
If you feel thumper will do the job you want, go for it. I would suggest guys who have experience with TW heads and can 'fix' the key area's that need attention or one of the known cnc places (fox lake, tea)
Let me know if you wanna travel here for a whoopin
Yeah, I forgot about you went with the lighter weight parts. 
I would have gone that route if I wasn't going full drag. I am going to look into other head porting places as well, just haven't yet. CNC is awesome, but the work is no better than the programmer.
If I travel that far, I'll be sure to have a plate that will be perfect fit for your ass!!! Don't forget, in the south, we tend to overcook things into soggy messes!!!!!!!!
I would have gone that route if I wasn't going full drag. I am going to look into other head porting places as well, just haven't yet. CNC is awesome, but the work is no better than the programmer. If I travel that far, I'll be sure to have a plate that will be perfect fit for your ass!!! Don't forget, in the south, we tend to overcook things into soggy messes!!!!!!!!
bluevenom867
I will have images of molesting stuffed animals in
90mustangGT said:Yeah, I forgot about you went with the lighter weight parts.
If I travel that far, I'll be sure to have a plate that will be perfect fit for your ass!!! Don't forget, in the south, we tend to overcook things into soggy messes!!!!!!!!
www.totalengineairflow.com
They did and awsome job on our Track Heat's were currently runing on the 408.
bluevenom867
I will have images of molesting stuffed animals in
90mustangGT said:Yeah, I forgot about you went with the lighter weight parts.
If you spray you'll feel better with the beefer rods.
And yes,at the price of a carb plate set-up its very easy to get into nitrous and run some fast times.
The Ultra light rods are not the best for heavy shots of N2O or boost in the long run due to how they are designed.
However they will work and lighter parts are always better on bearings....
Jason if you have someone interested in the TW go Vic Jr's, Vic Jr intake, soild roller and lets go 10's!
However they will work and lighter parts are always better on bearings....
Jason if you have someone interested in the TW go Vic Jr's, Vic Jr intake, soild roller and lets go 10's!
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