Cast iron
Le Mans Master
Joined: Oct 2007
Posts: 7,453
Likes: 976
From: RI, Now Franklin/Nashville TN
Some good points made above, but the bottom line is that HP/TQ differences between the aftermarket intakes versus the OEM ones are often very small differences, X2 on big gross HP/TQ modified Gen 1 SBC engines, since 5, 7, 10, 12 HP/TQ on a 425-450 Gross HP engine in the real world would barely be perceptible to the driver. Yes the numbers are the numbers on a dyno but often do not translate into meaningful differences on the street. Take a 12 HP/TQ increase on a engine dyno on a 425 Gross HP/TQ SBC V8 might translate into, at best, 6-7 hp/Tq at the rear wheels. Think about those numbers when you are considering the engines total output! Even on a stock engine in the 200 hp range, 6-7 HP/TQ MIGHT be barely felt at the wheels.
I just read an intake comparison with the ZZ4 versus most of the edelbrocks (I will focus on the RPM). At the top rpm's, the edelbrock performer RPM made about 4 more HP than the ZZ4. The ZZ4 made about 10 TQ MORE than the performer RPM at the low end and much more TQ in the mid range than the performer RPM. As my builder told me, constantly, when I rebuilt my L-82, NOT to focus on top end power on the street for the upgraded/rebuilt L-82 355 for what my goals but mostly on mid range tq on the street. He was spot on.
I have brought this comparison over the years on the forum when a fellow forum member with a similar 78 L-82 4 speed with 3.70 gears to my 78 stock at the time L-82 4 speed on the same dyno with similar 2.5 inch dual exhausts (mine with more restrictive Monza mufflers), my Holley 4175 650 CFM vacuum secondary spreadbore versus his OEM Qjet, no emissions for either engine, my L-82 had weak compression cylinder 6, OEM L-82 Cam on mine versus his aftermarket performance cam, and lastly, my OEM aluminum stock L-82 intake versus his Performer RPM. Summary, similar L-82's one pretty stock the other L-82 with an aftermarket cam and performer RPM intake. Same dyno....results:
My 78 stockish L-82 best pull was 233 RWHP with a weak compression Cylinder versus his L-82 with aftermarket cam and Performer RPM, 248 RWHP. For those good at math, that is a "gigantic" 15 RWHP with an aftermarket cam and performer RPM versus my L-82 cam and L-82 aluminum intake. To me the value proposition is just not there for aftermarket intakes only with hard numbers and underwhelming real world performance results like that.........
I just read an intake comparison with the ZZ4 versus most of the edelbrocks (I will focus on the RPM). At the top rpm's, the edelbrock performer RPM made about 4 more HP than the ZZ4. The ZZ4 made about 10 TQ MORE than the performer RPM at the low end and much more TQ in the mid range than the performer RPM. As my builder told me, constantly, when I rebuilt my L-82, NOT to focus on top end power on the street for the upgraded/rebuilt L-82 355 for what my goals but mostly on mid range tq on the street. He was spot on.
I have brought this comparison over the years on the forum when a fellow forum member with a similar 78 L-82 4 speed with 3.70 gears to my 78 stock at the time L-82 4 speed on the same dyno with similar 2.5 inch dual exhausts (mine with more restrictive Monza mufflers), my Holley 4175 650 CFM vacuum secondary spreadbore versus his OEM Qjet, no emissions for either engine, my L-82 had weak compression cylinder 6, OEM L-82 Cam on mine versus his aftermarket performance cam, and lastly, my OEM aluminum stock L-82 intake versus his Performer RPM. Summary, similar L-82's one pretty stock the other L-82 with an aftermarket cam and performer RPM intake. Same dyno....results:
My 78 stockish L-82 best pull was 233 RWHP with a weak compression Cylinder versus his L-82 with aftermarket cam and Performer RPM, 248 RWHP. For those good at math, that is a "gigantic" 15 RWHP with an aftermarket cam and performer RPM versus my L-82 cam and L-82 aluminum intake. To me the value proposition is just not there for aftermarket intakes only with hard numbers and underwhelming real world performance results like that.........
Le Mans Master
Joined: May 2007
Posts: 5,028
Likes: 1,120
From: North tonawanda NY
Some good points made above, but the bottom line is that HP/TQ differences between the aftermarket intakes versus the OEM ones are often very small differences, X2 on big gross HP/TQ modified Gen 1 SBC engines, since 5, 7, 10, 12 HP/TQ on a 425-450 Gross HP engine in the real world would barely be perceptible to the driver. Yes the numbers are the numbers on a dyno but often do not translate into meaningful differences on the street. Take a 12 HP/TQ increase on a engine dyno on a 425 Gross HP/TQ SBC V8 might translate into, at best, 6-7 hp/Tq at the rear wheels. Think about those numbers when you are considering the engines total output! Even on a stock engine in the 200 hp range, 6-7 HP/TQ MIGHT be barely felt at the wheels.
I just read an intake comparison with the ZZ4 versus most of the edelbrocks (I will focus on the RPM). At the top rpm's, the edelbrock performer RPM made about 4 more HP than the ZZ4. The ZZ4 made about 10 TQ MORE than the performer RPM at the low end and much more TQ in the mid range than the performer RPM. As my builder told me, constantly, when I rebuilt my L-82, NOT to focus on top end power on the street for the upgraded/rebuilt L-82 355 for what my goals but mostly on mid range tq on the street. He was spot on.
I have brought this comparison over the years on the forum when a fellow forum member with a similar 78 L-82 4 speed with 3.70 gears to my 78 stock at the time L-82 4 speed on the same dyno with similar 2.5 inch dual exhausts (mine with more restrictive Monza mufflers), my Holley 4175 650 CFM vacuum secondary spreadbore versus his OEM Qjet, no emissions for either engine, my L-82 had weak compression cylinder 6, OEM L-82 Cam on mine versus his aftermarket performance cam, and lastly, my OEM aluminum stock L-82 intake versus his Performer RPM. Summary, similar L-82's one pretty stock the other L-82 with an aftermarket cam and performer RPM intake. Same dyno....results:
My 78 stockish L-82 best pull was 233 RWHP with a weak compression Cylinder versus his L-82 with aftermarket cam and Performer RPM, 248 RWHP. For those good at math, that is a "gigantic" 15 RWHP with an aftermarket cam and performer RPM versus my L-82 cam and L-82 aluminum intake. To me the value proposition is just not there for aftermarket intakes only with hard numbers and underwhelming real world performance results like that.........
I just read an intake comparison with the ZZ4 versus most of the edelbrocks (I will focus on the RPM). At the top rpm's, the edelbrock performer RPM made about 4 more HP than the ZZ4. The ZZ4 made about 10 TQ MORE than the performer RPM at the low end and much more TQ in the mid range than the performer RPM. As my builder told me, constantly, when I rebuilt my L-82, NOT to focus on top end power on the street for the upgraded/rebuilt L-82 355 for what my goals but mostly on mid range tq on the street. He was spot on.
I have brought this comparison over the years on the forum when a fellow forum member with a similar 78 L-82 4 speed with 3.70 gears to my 78 stock at the time L-82 4 speed on the same dyno with similar 2.5 inch dual exhausts (mine with more restrictive Monza mufflers), my Holley 4175 650 CFM vacuum secondary spreadbore versus his OEM Qjet, no emissions for either engine, my L-82 had weak compression cylinder 6, OEM L-82 Cam on mine versus his aftermarket performance cam, and lastly, my OEM aluminum stock L-82 intake versus his Performer RPM. Summary, similar L-82's one pretty stock the other L-82 with an aftermarket cam and performer RPM intake. Same dyno....results:
My 78 stockish L-82 best pull was 233 RWHP with a weak compression Cylinder versus his L-82 with aftermarket cam and Performer RPM, 248 RWHP. For those good at math, that is a "gigantic" 15 RWHP with an aftermarket cam and performer RPM versus my L-82 cam and L-82 aluminum intake. To me the value proposition is just not there for aftermarket intakes only with hard numbers and underwhelming real world performance results like that.........
Unless im mistaken the performer rpm is the older obsolete design according to edelbrock.. I might be mistaken now because they might have added it but the regular rpm didnt have the center divider cutout which will net more HP every time at the cost of a couple lbs of down low torque. I feel they are very worth the $50-75 you can easily pick them for used though. I sold a performer rpm painted black for $75 10-12 years back. along with a brand new performer spread bore and yet a second silver performer rpm intake all for between 50-75 each. Ive since used a couple polished assault brand intakes which I ported myself for fun currently the air gap version. I like these because they are polished and easier to keep clean also they give me an extra 1/4" of clearance vs the edelbrock versions which even though I use a spacer on top of them leaves me more room to adjust things around with my different spacers and air cleaners I experimented with.
I know weve beat this horse to death but engine masters did 2 sbc intake shootouts on a dyno and they proved both the rpm and the air gap had basically identical performance once you notched the center divider out on the rpm. Edelbrock was smart and did this to the air gap only when they released it to show a performance boost with it over the rpm and sell more intakes to folks who already had the rpm and would otherwise just notch their old intakes vs buy a new air gap.
Last edited by augiedoggy; Dec 30, 2025 at 06:57 PM.
Racer
Joined: Jan 2016
Posts: 290
Likes: 78
IMO, for a street 5500-6000 rpm street set up, the single best reason to ditch the old cast iron intake for a modern aluminum one is the material it’s made of. Besides being way lighter the heat shedding of the aluminum intake makes it worth it to lessen the chances of fuel boiling/ vapor lock and carb plate warpage. Especially after shut down when that cast iron intake turns into a radiator heater.
