C3 Intake manifold selection
Le Mans Master
Joined: Oct 2007
Posts: 7,444
Likes: 970
From: Tennessee/Rhode Island
I’m running the Performer RPM Air Gap(7501) on my 78. It fits. You need a drop base air cleaner, the stock single or dual snorkel intake won’t work.
The Performer Air Gap (2601) is a performer with the air gap tech. This will perform VERY close to a 2101 Performer until you hit heat soak, then you will see a little bit of benefit.
I’ve read this article MANY times. I used it in my own decision making process. You need to look at that article a bit more carefully - it’s got a significant misprint in it. The ZZ4 intake in the first chart shows peak HP at 471. If you look at the “Peak Torque And Horsepower” chart at the bottom of the article, it shows the ZZ4 at 451 HP. Vs 474 on the RPM Air-Gap.(7501) If you are looking to buy an intake manifold, a 23HP gain on a moderate engine is substantial. The RPM Air Gap also makes more torque @ 3K than the ZZ4 - meaning from 3000 up (and probably just a bit before) you’re going to see more power - and with that engine, the extra 23hp at peak really cements it.
I’ve got a ZZ4 intake, a Weiand Team G 7525 and a 7501 RPM Air Gap at my house. The ZZ4 and RPM blow the Weiand out of the water in terms of fit and finish. The RPM Air Gap does low, mid and high better than either of the two.
Agreed on stock. If your peak power is beyond 5000 RPM, odds are an intake will help. “Moderate” has a broad range of interpretations.
Please re-read my post and the article. You’ll see that’s not obviously the best path. Especially since you’ve got a ported intake already.
At Summit these ZZ4 intakes are $322. The RPM Air Gap is $289. You do have to eat the cost of another air cleaner, of course - so the Air Gap will end up the same or more expensive depending on which direction you go.
On my re-read though, there’s a point I was wrong on. The ZZ4 seems to do just a bit better than the 2101 Performer with the engine in the article.
The Performer Air Gap (2601) is a performer with the air gap tech. This will perform VERY close to a 2101 Performer until you hit heat soak, then you will see a little bit of benefit.
I’ve read this article MANY times. I used it in my own decision making process. You need to look at that article a bit more carefully - it’s got a significant misprint in it. The ZZ4 intake in the first chart shows peak HP at 471. If you look at the “Peak Torque And Horsepower” chart at the bottom of the article, it shows the ZZ4 at 451 HP. Vs 474 on the RPM Air-Gap.(7501) If you are looking to buy an intake manifold, a 23HP gain on a moderate engine is substantial. The RPM Air Gap also makes more torque @ 3K than the ZZ4 - meaning from 3000 up (and probably just a bit before) you’re going to see more power - and with that engine, the extra 23hp at peak really cements it.
I’ve got a ZZ4 intake, a Weiand Team G 7525 and a 7501 RPM Air Gap at my house. The ZZ4 and RPM blow the Weiand out of the water in terms of fit and finish. The RPM Air Gap does low, mid and high better than either of the two.
Agreed on stock. If your peak power is beyond 5000 RPM, odds are an intake will help. “Moderate” has a broad range of interpretations.
Please re-read my post and the article. You’ll see that’s not obviously the best path. Especially since you’ve got a ported intake already.
At Summit these ZZ4 intakes are $322. The RPM Air Gap is $289. You do have to eat the cost of another air cleaner, of course - so the Air Gap will end up the same or more expensive depending on which direction you go.
On my re-read though, there’s a point I was wrong on. The ZZ4 seems to do just a bit better than the 2101 Performer with the engine in the article.
Note that the relatively short Edelbrock 2601 Performer Air Gap manifold makes more torque at 3,000 than any other manifold. Compare its 478 lb-ft to the Jegs manifold's 462 lb-ft, to see that the Air Gap makes 16 lb-ft more torque. We guarantee you will feel 16 lb-ft in the seat of your pants. We think this can be partially attributed to the plenum-wall cutout on the Jegs manifold, but the TFS and Dart manifolds also have this feature, and those manifolds are only down by a single-digit compared with the Edelbrock. For a mild street engine (especially with stock or near-stock heads), this low-speed torque value should be given greater consideration.
[QUOTE]Now let's talk peak horsepower. While the field gets a little more spread out in this category, the difference between the Third-Place Jegs Champion and the 21st place Edelbrock Performer is only 15 hp—barely a 3 percent increase. By now, it should be obvious that any manifold you choose within the top 20 will work just fine for a street small-block. Keep in mind that this test used really good heads on a large engine. With a mild 350 with near-stock heads, the differences in these manifolds would be much narrower.[/QUOTE]
Frankly, any of the manifolds ranked in the top 15 of all our evaluations are solid choices that won't leave you with buyer's remorse.
Last edited by jb78L-82; Sep 21, 2020 at 01:47 PM.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Now let's talk peak horsepower. While the field gets a little more spread out in this category, the difference between the Third-Place Jegs Champion and the 21st place Edelbrock Performer is only 15 hp—barely a 3 percent increase. By now, it should be obvious that any manifold you choose within the top 20 will work just fine for a street small-block. Keep in mind that this test used really good heads on a large engine. With a mild 350 with near-stock heads, the differences in these manifolds would be much narrower
Where I disagree with you is on the supremacy of the ZZ4 intake. And like I said - a 23 hp gap between the ZZ4 and the 7501 - that's substantial, and if you're starting with no intake at all, it's an easy decision for me. More power from 3000 RPM on up, plus higher resistance to heat soak and ports that are a much better fit for larger heads.
Burning Brakes
Joined: Jun 2020
Posts: 881
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