Does Cutting Down The Divider On A Dual Plane Intake Manifold Help

I show the horsepower change with cutting down the divider on a dual plane intake manifold and share which carb spacer worked best.

[txredline]

Eric you provide fact based information. I appreciate what you are doing. Keep up the great work.

[SCmaro]

With small runners and ports people often assume it will make all the torque not realizing the torque is a function of volumetric efficiency not air velocity. It's possible for a larger runner and port to make more torque with somewhat less velocity just by filling the cylinder more effectively.

[yarrdayarrdayarrda]

Keep in mind this is a fairly high RPM test. For those building street engines, 2500 to 4000 is where you're going to be most of the time, so a few HP upstairs is great, but you want torque and a happy engine when it's turning 2500 to 3500 driving down the road at part throttle.

I've witnessed open spacers making 5 to 15 HP extra while running the dyno, and it's good for bragging rights, it will always hurt torque numbers down low, and will negatively effect drivability.

[shawnwalsh]

Folks, information is priceless. Spending money on books is cheap insurance if you're a novice or a professional..

[tomstrum]

Thx Eric for showing this....Like forever, We've been Told Cutting down the Divider Favored Top for showing what really

[immanutt]

Absolutely without a doubt this tutorial is the most comprehensive in depth cut through the chase proven intake spacer data log ever

[stevenbean]

I love how your dyno room looks like a cozy room ! id cut the divider down just to enable running a 3 barrel

[angelsanchez]

You always provide us with the correct information. And all the graphs to prove the results. Good job keep up the good work.

[peskypeet]

👍 Doing good things Mr Weingartner.
Your testing and information is appreciated.

[aubreycollom]

I'm not a chevy guy, but I really dig your videos. That's a lot of research at your expense. Thank you for the great information!

[charlieperry]

I love the honesty and the humble attitude you give... the content and information from all your videos is awesome. Thanks for taking the time to share...

[BillyWilliams-de]

Thanks for all your help.
Finding the perfect gen 1 small block, for my 1968 Nova.
Amazing Horsepower 👏

[duke]

Interesting to see varying results from lowering the dividing wall. Ben Alameda did a video on his observations with a SBF netting a Loss of 27hp from 556hp after it was lowered.

[kramrollin]

You know, it is the year 2023, and yes your video is great, but back in the ancient times, we use to have strange things called books and magazines. Back in the early 1900 and 70s, Chrysler engineers wrote the Direct Connection manuals on go fast Mopars. The recommended Small Block race manifold, was the Edelbrock LD340 dual plane for Super Stock and all performance. Back then they ran 10s in 1900 and 70s remember. The Race Modification to the to cut down the divider to 3/8" off the floor. In other words what you have done. They dynoed all their mods. It made to best power for the cars at the time. Isnt it amazing that you can still provide this info to newbies, that was already known by us all 50 years ago. In fairness, I bought my DC manuals in the early 80s....so yes, I knew of this mod since then....and yes I have an LD340.😄
Keep the info nobody reads book anymore, or looks up already proven info....Perhaps more newbies should be asking the oldbies how its

[hangfire]

Nice test. My uncle bought the AFR for a 406 build in a 65 C10. I shared the videos with him and mentioned opting for the open spacer for some extra power. No way I would have know this info without your testing.

[JohnDoe-udcc]

The afr is what I would go with. That huge bottom end gain is worth the few hp loss on the top end.

[donnelhuddleston]

It used to be worth 15 to 25 HP on a Small block Chevy in the 70's & 80's, it's probably worth more today with engine builders making so much more power than they did back in the day, yes its such a popular mod that the air gap Manifold came out.

[danmyers]

The Edelbrock Performer RPM air gap has slightly longer runners than the non air gap Performer in addition to the lowered IAC benefits of the air gap. I have often heard engine builders say that cutting down the divider on a dual plane manifold can slightly improve cylinder to cylinder distribution issues inherent in the manifold design. The only way to accurately verify the AFR in each cylinder is through a temp sensor in each exhaust header. A single sensor in each collector gives an average of the AFR’s in that bank. The individual AFR’s can vary significantly, sometimes as much as 3 points! While the overall AF may be 12.5 you could easily have one or more cylinders at 15.0+.

[donaldhalls]

Once again very informative, information, very well presented, thanks for sharing, all the best to you and your loved ones

[c.n.]

Very nice work here a lot of it!! When I see and read info like this I'm reminded of the IROC racing series. Their professional engine builders with the best most modern equipment struggled to get all the engines built completely the same to get the engines to perform equally . They always seemed to end up with one that was a slug and one that would run circles around the rest. It is certainly not feasible but a test of three differently built engines testing the manifolds and the performance differences would be interesting but a budget the size of GM would be necessary for that type of testing. My point is if people really want to know what is for their combination, they need to do what you always do and that is, test, test, test.