RPM Airgap vs. non-Airgap?

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J

jeeper

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It seems to me that the Airgap is the way to go for most cars that perform where I would like to be.

Here is my question: What is the real world difference in performance between the two on a street car?

I was speaking to a friend in a much milder climate and he said that his really does not atomize the fuel very well when cold. I could easily end up running my car at 30 degrees in the morning and 90 in the afternoon so I am concerned.

I'm just wondering if the advantage is worth the potential hassle.

Thanks, ROB
 
I'd have to agree with your friend and go with a Pefromer RPM. It is the same Intake as the Air-Gap, just without the exhaust crossover/being open like the airgap is. Just to avoid any cold weather issues that may come up. That intake will stay pretty cool for awhile before underhood temps get high enough to warm it up because there is no exhaust-crossover. my performer rpm runs pretty well in 30* or even lately it being 106*+ it hasnt acted up. I'd go witha performer RPM. just my .02cents.
 
That's what I wanted to hear. We live in similar elevations except you get alot hotter.

I live at the base of Crater Lake in rural Oregon and we get some pretty good swings in temp here.

Thanks Goody, ROB
 
Your better off with the regular RPM as posed to the air-gap model if you see a big temp swing daily or simply drive it when it gets cold.
My air gaped 360 with Carter 750 E-choke will take about 10 min.s to fully warm up and good to go in the cold days of fall. (Like a big block)
But as soon as I go down the road some the choke will close up a bit dual to the cooling of the air all around the engine and intake.
 
I have driven my car with the CrossWind manifold in temps down to the teens and it takes about 4 miles for it to get up to temperature. In 80 degree temps it takes about 2 miles for it to get up to temp.
 
I dont think there is enough differance in the intakes to woory about. If I were buying one new I would get the air gap. If I already had a RPM or an LD340 for that matter I wouldnt waste my money. Niether intake has a heat crossover anyways.
 
I'm not trying to eek the last HP out of it. It sounds like you folks have experienced the same issues that my friend has in a milder climate.

I guess that settles that question.

Thank you, ROB
 
Heating of the intake really does make a big difference in cooler climates. Several years ago when I was a kid I read in a Hot Rod mag that a cooler intake would make more torque so I made block off plates for the heat cross over and installed them and it did make some more power but it was in the fall and when winter came along here in Illinois man was that thing cold natured. The fuel economy also went out the window. I finally took the block off plates back out and enjoyed a much smoother running car that was 3-4 mpg better on gas. I don't know if these results are typical but that's what I experienced. I tried to make up for things by re-tuning but really didn't gain anything back as far as drivaiblity.
 
swingtown said:
why not buy a m1 from mother mopar?
Click to expand...

Because it is not as good an intake as either the RPM or Air-Gap. The M1 dual plane is equivalent to the plane performer.
 
It also has a higher RPM ceiling and is better suited for a more agresive cam/engine/rear ratio/car.
The intake does well for a single plane. No doubt!
 
I use the Edelbrock AirGap...but it doesn't get cold here in Texas (Texans would probably disagree with me).
 
Here in New Mexico it can get down in the teens in the winter and my 318 starts good, just takes a little bit to warm up. I am running the airgap and if I were going to buy another it would be the same. Afterall most people let their motors warm up anyway, in cold weather.
 
Ha ha ha ha, wish I had that warm up time option, LOL. Even when I did, the cold air comes in and kicks the choke back on. If the car was more true to daliy driver, in the N.Y. cold, it would be the regular RPM with heat tube to stock aircleaner etc...........
 
I'm trading in my M1 for a Performer RPM non-airgap. But before I do it I am going to run a a little test between the two. I plan on posting the results when I Get the car running. Never gets really cold here.
 
Yeah I'd love to know what you find out also. Please post the rest of your combo also if you would please as that is an important part also.
 
Here's the combo as is right now. 340 0.30 over, 10.1:1 pistons, comp cam 292, .501 lift, 244 duration, ported and polished J heads, M1 intake, 750 holley 3310, FBO ignition, 5-speed Keisler, 8 3/4 3.91 gears Detroit truetrac diff. Stock 5x4 axles. Wheels don't know yet. Currently have SWS 15 x 5.5. Will try to get a 15 x 7 drag radials for the strip

Test will be against the RPM and Mighty Demon 650 and FBO ignition

What parameters should be included in the test? e.t., 60ft, idle characteristics, Shifting characteristics, mpg, detonation issues, etc

This should be a fun test I think. I need the tuning practice
 
Dave you have a very nice build there. Hot street and weekend warrior setup. The test would be better if you could only change out the manifold only cause the additional carb change may have an affect also that makes the manifold look better or worse is you know what I mean. I understand it's more work though.

I'd say you have the paramaters covered pretty good. At the moment I can't think of any else.

BTW: Have you ran your car with your current setup?
 
It would be hard to make a perfect comparo. Many changes are possible.

Just try a straight up of whats there to whats being sought.
Things like, jetting changes should be included as well as,
60 ft times, 1/8 & 1/4 times and speed (Trap speed)
Also, if you could possibly included mileage.....

Have fun, good luck.
 
This is my first attempt at building a street/occasional strip car. I have not run this car or engine before. Good point on the carb changes. Hopefully I can get an ideal test setup but could be interesting none the less.

After talking with FBO on my setup it sounds like I will have detonation issues using crappy 91 octane gas available here in California. Is there a place where I can get 92/93 in Socal? What are you guys doing to help with the low octane issues and detonation problems associateed with it. JB Additives/Boosts/Fuel Mixing etc?

Maybe a new thread on fuels for our loder muscle cars?
 
dave
is that a true calculated 10.1 CR? If it is and with the cam you have 244 it will bleed off some compression at lower rpms, so if the advance curve all in is delayed to 2800-3000rpm you should be okay - on the verg though.
The Air-gap is supposed to be worth 5-7hp over the Performer - but in cooler weather like we have in most of the year (okay 10mths) they are a bit of a pain waiting for warmup - if it ever does.

With the RPM and 650demon, you will be amazed at the overall performance difference - going from boggy low speed to tire ripping is my speculation - that and a little first hand experience. Save yourself some work - just put it on and let it rip.

On another note:
Your outside garage setup pisses my off everytime I see that pic -LOL
I've had the forced air heater in my garage going for a month already and its only early Nov. - I can't wait until January!! :cussing:
 
daves66valiant said:
This is my first attempt at building a street/occasional strip car. I have not run this car or engine before. Good point on the carb changes. Hopefully I can get an ideal test setup but could be interesting none the less.

After talking with FBO on my setup it sounds like I will have detonation issues using crappy 91 octane gas available here in California. Is there a place where I can get 92/93 in Socal? What are you guys doing to help with the low octane issues and detonation problems associateed with it. JB Additives/Boosts/Fuel Mixing etc?

Maybe a new thread on fuels for our loder muscle cars?
Click to expand...

I feel your pain with the crappy 91 oct. we have it here in vegas. I have to run about a 35-40% mix of 100oct with 91 on my 9.7:1 318 :sad1:
 
I always leave the exhaust crossover open, yeah I tryed it the other way but unless its over 70 I feel its better to have it. Now under the carb I have a spacer that keeps the carb cool. Even after the motor sits when hot after you drive it the incoming air cools the carb off.

OH and scince I gotten a MSD 7al box and 8251 coil theres no need for any type of warm up even now at around 40 degress. Motor starts up and idles in gear-rough but a good idle-I just drive it for 5 mins. and its ready to kick but again. Best $550 I spent I believe.
 
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