Now that I am going Quadrajet, I need a new manifold. Tell me why I need a Performer RPM Quadrajet instead of a straight Performer Quadrajet or Performer Air Gap with the following engine:

ZZ4 Short Block
AFR 180 Eliminator Heads 65cc (10:1 compression)
Factory Hydraulic Roller Lifters
Comp Cam Extreme Energy 270HR (218/224 @ 050, .500 lift) - Advertised at 1500-5400 RPM operating range
Hedman 1-5/8 Inch Headers
Magnaflow 2-1/2 X Flow Exhaust
Four speed Manual Transmission

With the cam operating range at 5400 RPM, why bother with the RPM manifolds?? The downside to the RPM is the need to go drop base aircleaner. With the straight Performer or Performer Air Gap I could use larger open air filter OR even my stock 77 cold air system (although concerned about the small opening that may be choke in the system), all original parts i.e. throttle bracket and fuel line. I have read enough to know that what matters is matching cam to the heads to the intake and driving style. I am not going to race the car, so RPM above 5500 RPM is not my concern. My biggest hangup is spending the extra money on the AFR heads to choke it, even if its only a matter of principle??

 

2101 and 3701 Performer are a compliment to the AFR 180s with your cam. Larger heads and bigger cam and I'd go with the RPM Air Gap. Or, go drop-base with the RPM air gap and you have close to what Super Chevy assembled.

Good article from super chevy mag:
http://www.superchevy.com/how-to/148...-engine-build/

 

We have very similar engines except my block is the stock L-82 one border .030 over-355. I also have the AFR 180 65CC Eliminator aluminum heads with 10-10.2:1 Compression-Felpro .015 head gasket. I am using the Howard Retro Roller-.525/.525 lift, 219/225 duration, LSA 110-operating range 1,500-5,600 RPM with the OEM L-82 aluminum intake which is very similar to the Performer. 99% of the time the engine will stay below 5,500 RPM and after researching the differences in the Performer Series intakes and speaking with the engine builder who did my short block, I settled on keeping the L-82 aluminum intake since there is no difference between it and the Edelbrock Performer, especially in the RPM range I intended to use the engine. The Performer RPM/air gap have a slight advantage over 6,000 RPM. I wanted to keep the L-82 Stock air cleaner assembly as well which was another consideration since the engine looks pretty much like a stock L-82-the goal…

I am about to pull the trigger on the American Racing long tube 1 5/8 inch headers in place of the shorty design McJacks on the car presently but pricey...

 

Great article!

That motor is very similar to mine only i have vortec heads and a 670 cfm holley.

My motor makes an honest 400 hp on the dyno.

 

I'd stay away from the RPM version just for low torque considerations. It's annoying to me to have to drive a car that requires lots of rpm to let the clutch out due to low bottom end torque.
The air gap has advantage of cooler intake charge vs the performer, but I don't know if the stock air intake assembly can then fit on.
The performer can be made nearly as good with an oil baffle added and the crossover heat blocked off, which is what I did with my 2101.

If a guy wants more RPM capability from the 2101 You can run an open gasket vs the 4 hole gasket. This would seem to me to be similar to the cut down divider in the RPM version, allowing primaries and secondaries to "see" each other.

I run the stock intake system but modified to allow more air in. As you guessed, the stock installation is air restrictive in it's stock form. You can see my mod here on the pass side of the engine. 2" hose from air cleaner to wiper tray area. Also removed flap in the snorkel and added a "flap" that can open on demand if needed. The flap would draw in under hood air, so less desirable than the wiper tray air.








Running an open element eliminates the possibility of cool air for the intake reducing power and torque.

 

That is a great article

After I install the ARH headers, the distributor will be recurved and adjustable secondaries will be installed for better tuning on my Holley 650 Vacuum secondary carb. The 355 in that article is VERY similar to mine with the AFR 180 heads, roller cam with 525/525 lift, similar duration, roller tipped 1.52 rockers, but I am using the OEM aluminum L-82 intake…I expect the same HP/Torque as the engine in the article: 425 Gross HP/450 Torque. When they changed intakes though in the article they also changed the carb to a 750 CFM Holley with the torque increase from 6-19 Ft-lbs-problem is that they added the 750 Carb at the same time so that muddies the waters a bit.

 

Another aspect of this for consideration....I ruled out the stock 77 single snorkel air cleaner, because I think it will be restrictive and not interested in the later model dual snorkel.

Option 1 - go with straight Performer or Performer Air Gap and I can use a standard 14 inch open air cleaner, maybe 3-1/2 inch K&N. Everything easily fits, and looks good.

Option 2 - go with Performer RPM Quadrajet, I will have to use a Drop Base air cleaner due to the .75 inch taller as I intended with the squarebore Performer RPM in the picture. Does the drop base restrict airflow, due to smaller distance between top of carb and floor of air cleaner top floor, possibly negating any advantage the Performer RPM has over the Performer. What do you think? Overthinking?

 

As long as you measure the vent clearance no impact to performance.

 

Is it aesthetics you're going for with the open element? If so, I agree open element looks better, but are bad for performance unless you can feed it a good supply of cooler air.
Also keep in mind with the Q-jet you are going to need at least 1/4" for an insulating gasket to keep the fuel in the bowl from percolating. Either that or some other heat shielding method, in either case it's gonna take some amount of space to do it.

 

I use a 1.5 inch drop base, 3 inch open element air cleaner on my car. I have tested that, on the drag strip, against the stock, single snorkel air cleaner, with the cold air ducting in place. The drop base, open element unit allowed the car to run 3 tenths quicker than the stock unit. This is on a mild 383 engine.
I don't think the cold air feature is significant, once the car is moving. The air blowing through the grill isn't heated significantly by the radiator as speeds increase.

 

I have spent several more hours today roaming internet on many sites more performance related than here, and come up with a few more points:

- The Performer RPM only gives up a very small amount of torque at lower RPM's to the straight Performer, and adds big numbers on top end.....? If I get convinced it does add torque and power above 3000 RPM, I can convince myself that is the way to go. If it only adds above 5500, I really don't see a benefit to it, given the sacrifices necessary to install it.

- Cold air intakes theoretically can add performance, but I think it is small. And more importantly for me, I want a strong engine, but there are limits as to what I will do, and that includes adding a bunch of ugliness to my engine compartment to gain a little more power. I am not racing, just want as strong engine I can get, within my limitations.

- There are people who I trust who believe that on a street engine, an open air filter is far better than any restrictive cold air system. I am not burdened with extra junk like airconditioning, air pumps, etc, so maybe with less hardware, and more space, maybe my engine compartment will see more airflow, not the heat furnace that it supposedly is.

- Air gap manifolds sound good in theory, but in reality don't do much. In fact, a downside not talked about much is that fuel atomization can be affected by lack of heat during start and in colder weather operations. Talk of fuel drop out, etc, scares me away.

- You can find any answer you want about any component or mod on a car if you search long enough. There are people who believe 180 degree opposite ideas are the best. I have to always try to keep focused on what my particular driving style is and what I care about, cause its really easy to get swayed by hype, marketing and self proclaimed experts. I have read enough and picked certain people, like Lars, Billa, Mako to believe in, and just hope they are the right ones to believe!! Thanks everyone.

 

Thanks BK, I agree. Its not even that I have the experience you have, its more a common sense viewpoint that I have. Nobody can argue that a cold air charge won't produce more power. I have experienced the difference with cold air when flying in piston airplanes, riding motorcycles in cold weather, and even in daily drivers. BUT, a cold air intake versus open air filter in an engine compartment is only the difference in temp between air outside the compartment versus inside. Its not REALLY cold air.

 

the air gap intake is a little cold natured compared to the performer. i run with no choke my car starts with one pump when cold and fires instantly probably with 1/2 a crank, i can drive it off normally and it never stalls. however i have to drive it a good ways in cool sub 60 degree weather before i can just nail it from a dead idle, but i can live with it because when fully warmed up it pulls like an old soo-line freight train.

 

Cold is a relative term. 80* F outside air temp vs 160* under hood temp is a significant difference in temperature.
I think BK fails to understand that if he had a cold air system that was sufficient for the demands of the engine vs an open element that draws in only under hood air but also meets the demands of the engine that the cold air would win out every time. guaranteed!! Comparing an insufficient cold air system to an open element is not a fair comparison.
In a drag race scenario where the engine is run hard for a very short period of time and is not yet heat soaked under the hood the difference may be less pronounced, but it would be there.
Do you really believe that your engine produces the same power at an ambient temp of 60* vs one at 100*?
Since you are a pilot then you may have experienced density altitude and it's effects to the power production of an engine. Not to mention the thrust produced by the prop and the lift provided by your wings and horizontal stab and elevator. All are effected.
If you have say 1000 particles of air per cubic inch at 60*F, just as a random number for example, in an open system (the atmosphere) and 21% of it is O2 which is what is needed to burn fuel. Do you believe that at 100* F there has been no expansion of the air and there are still 1000 particles of air per cubic inch?
Of course not.
Fuel needs O2 to burn. Fuel burns best for power approximately 12.5:1 in our carbed engines. If that is 12.5 parts air and that air is less dense what has to happen to the amount of fuel to still achieve the optimum mixture for power?
If you reduce fuel to achieve that optimum mixture for power, you just reduced power, period.
The air since it is less dense does not achieve the same pressure as previously at a denser concentration so it also has reduced the power to the engine via less pressure exerted on the piston on the down stroke after the fuel has been burned.
If you don't believe me do a compression test on a 40* day and then do one on a 100* day. Note the difference. It will be smaller obviously than on a running engine as the engine is only turning at the cranking speed of your starter.

The air gap is a significant feature. The oil mist in the lifter valley is at least 212* F and likely higher at running temps. That oil mist is being deposited on the bottom outside of the runners of your intake. The heat from that oil is going to be dissipated by those runners. The runners are carrying fuel and air to the engine. That heat is added to the fuel and air mixture on it's way to the cylinder. Hotter intake charges detonate easier. Detonation forses richer fuel mixture or less timing than is optimal.

I run my engine with no choke. No problems at temps down to 40*, I haven't driven it in anything cooler.
My 2101 has an oil baffle and no crossover heat. So it behaves much like an air gap. Fuel drop out may be likely at cooler engine temps. However that is not when I want the power. I don't punch my throttle until everything is up to temp. This would include the intake manifold. It will inevitably heat up. An air gap can moderate how much it heats up. Better 160* underhood air than 212*+ lifter valley oil heating it.

What you do is up to you. And I agree cluttering up the engine compartment is not what everyone wants to do and is not as pleasing to the eye. Just understand the compromises.

 

I'd go with the rpm or the rpm airgap if it will clear, I can't remember, but you might need an adapter plate for the rpm series which would make it even taller. The drop base cleaner wont hurt as long as you dont use to small of a filter. You'll want to match the stall converter to the cam also.

DO MA NEU!

 

I run a performer air gap on my 73 and it's great an all but there are downs sides,
a) takes forever for the qjet to heat up (like 15-20 minutes)

B) I have profiler heads with 185cc runs and this intake barely covers them, when I had the 1204 gasket on you could see into the head ports I had to switch to a 1205,

C) the intake bolts in the middle are the most PITA to take out and put in lol

I have a Lunati 262/268 cam in mine which has around the same operating range your cam has, personally I'd rather go to the rpm because with the performer air gap I feel like I'm leaving power on the table

 

Got stock manual 4 speed transmission with 3.55 gears.

 

REELAV8R - I fully understand that my air cleaner test involves two variables in one test. I was trying to prove, for my own knowledge, which setup got my car down the track the fastest. My point about underhood air temperature is that, I believe that as the car's speed increases, the underhood temperature approaches the outside air temperature. As the amount of air passing thru the rad increases, in terms of cfm, its temperature gain decreases until it is negligable. With other air sources from under the car increasing as speed goes up I don't think the cold air supply is helpful. Now if it creates a ram air effect, thats different.

 

My cam operating range is advertised at 1500-5400 RPM.....I have manual transmission and 3:55 gears

The Performer or Performer Air Gap advertised at idle to 5500.

Performer RPM Quadrajet (my only option) - they do not make Air Gap for Quadrajet, and not interested in adapters. - advertised at 1500 - 6500.

Which intake matches my cam more closely?...and consider the excellent flow numbers of the AFR 180 heads. The cam and the RPM start at 1500, so that matches, but on the top end, my cam quits long before the 6500 RPM...so this again leads me to believe the RPM is wasted.

I just don't understand the part that a straight performer can produce more torque lower....how? Is it velocity?

If I thought the RPM produced more torque from say 3000 up than the Performer Air Gap, then RPM it is. Torque is what matters to me more than 6000 RPM numbers.

 

As was discussed in the other thread, you severely limit yourself with a Q junk.

The straight performer is probably what you are looking for. You won't have clearance issues with the performer.

Smooth off idle to 5500. Nice driver

If you can get the Performer RPM in spreadbore it better matches your cam.

You can get all the specs and tailor your setup from the Edelbrock website.

http://www.edelbrock.com/automotive/mc/manifolds/

I use a Performer RPM Air Gap, but I use a Holley Street Avenger.

I also have an L88 style hood with the air filter in the hood and cowl induction. So no clearance issues and lots of cold air.

I have 400 hp and tons of torque.