I'm looking to purchase one of these manifolds in the near future and was wondering what people's views were on whether the air gap is worth the extra cost. This is for a street car with a 289 stock with mild cam and AFR 265's in the future.
RPM vs. RPM air gap
- Thread starter 1967coupe
- Start date
dolfan87
Founding Member
That would require someone on here to have owned both types on the same engine.
The airgap is supposed to lower the incoming air/fuel charge because it's seperated from the base of the intake, but when the engine is at operating temp under a hood, how much does it really reduce the temp??
If you are on a tight budget, I would think the standard RPM would be fine.
87
The airgap is supposed to lower the incoming air/fuel charge because it's seperated from the base of the intake, but when the engine is at operating temp under a hood, how much does it really reduce the temp??
If you are on a tight budget, I would think the standard RPM would be fine.
87
dolfan87 said:
Agreed. The Air Gap is a cool idea and might be worth it for the wow factor if you have the extra cash, but if $ is a factor, I'm willing to bet you wouldn't really feel a difference between the two.
I have to disagree: I read several dyno tests on the Air Gap when it first came out and it blew the rpm away. It almost equalled the Victor Junior on the top end while still beating the rpm on the bottom in several different engine combos. True, the underhood heat was not taken into account, but the same heat will be there with the regular rpm manifold.
mustangdave said:
Cool!
I like hearing that. Too bad my car is rockin' the regular RPM.
Oh well, it was cutting edge when I bought it.
i bought the Professonal Products version of it. havent installed it yet, but it seems to be a decent casting, needs a little cleanup of some casting flash but nothing terrible. it was only 146 shipped brand spankin new. Its basically a carbon copy made in china version of the airgap for 100 bucks less. if money is a factor, check them out.
LOL I haven't owned the ford version, but if you look at the old chysler big block manifolds they are separated from the block via a valley pan (gasket). This keeps the manifold separated from the hot engine oil in the crankcase. The bottom side of our regular manifolds get that hot oil slung up onto it which raises the temp of the part of the manifold that the air/fuel mix passes through. Colder charge = better
SadbutTrue
Founding Member
1967coupe said:
was gonna say... AFR 265 lol? What do they flow? 1600 cfm at 1.1" lift? Rev to 12000 rpm?
If you can fit it, get the Air Gap. If not, the RPM is fine. Might want to look at the Weiand Stealth, shorter than both (i believe) but revs higher and I hear nothing but good stuff about it.
69 302/351c
Founding Member
Air Gap tests out better than the performer RPM but doesn't run as well in cold weather. My buddy has one and it takes a while to get heat in it.
BobV
20+ Year Stangneter 
On a 289/302, Air Gap and Performer RPM are the same height. If one fits, the other will also.
Only the 351 Air Gaps are taller.
Only the 351 Air Gaps are taller.
I called Edelbrock yesterday and they guaranteed me that it would have plenty of clearance with a 289. My buddy has a '68 with the RPM and it fits fine. Just had to call them to know if they were the same height.
Amazing how this 45 year old technology came roaring back a couple of years ago. Pontiac started doing this on stock motors in about 1960.
Also, even though you may save a little money, Edelbrock is an American company, owned by an American hot rodding pioneer, who makes his parts in America using American labor.
Please don't buy cheap chinese rip-offs.
Also, even though you may save a little money, Edelbrock is an American company, owned by an American hot rodding pioneer, who makes his parts in America using American labor.
Please don't buy cheap chinese rip-offs.
Great68
Founding Member
I have the RPM Air Gap manifold and AFR 165 heads, I haven't had the chance to drive it around a lot, but it definately rocks the world of my old Offenhauser intake.
Oh yeah, the Air Gap has slightly larger runners than the standard RPM, which makes it great for more cubic inches.
Oh yeah, the Air Gap has slightly larger runners than the standard RPM, which makes it great for more cubic inches.
