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Discussion Starter · #1 ·
Adding a 4150 style plate kit to my BBF, in my 72 F250 4x4.

Currently has an Edelbrock performer 460, Jomar power cone manifold spacer, and a Holley Sniper EFI. So this is a lower RPM truck engine, max 75 hp of spray.

Wondering if 1/2" thick, open plenum, NOS brand plate should go above, below, remove the power cone, different spacer, or something else.

Seems like the short open plenum plate may have similar effect as machining down the center divider like the perf RPM, perhaps making gains from power cone diminish
Thoughts?
Mad porters thoughts?


 

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My 2¢ is theory and then reality. Theory is to put the nitrous plate under the Jomar, as the Jomar needs to be against the carb for what it is trying to do. Whether it is doing anything for you or not, the nitrous plate above it would disrupt the flow and pooch it worse.

Reality is that you should use the combo and order that proves best, and that is found by testing. So, I would test two configurations, carb-Jomar-nitrous-manifold, and the other without the Jomar. If you can't make a track day out of it; get a G-force meter for your phone, accelerate to a specific point and decelerate, or a specific MPH and decelerate. Read the times from accel to decel G-points in several back-to-back runs. Use what works best, or shows promise to work best with further tuning of the combo.

Remember, this is all flow theory, does not require the use of nitrous for the comparison, and needs to be tested for results as your butt-dyno is useless. If not the track, find somewhere safe and away from your neighborhood. ;)
 

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Discussion Starter · #3 ·
I'm running TB EFI so part of what the power cone may do for a carb/venturi may not apply. My understanding is that the power cone spacer also allows the 2 sides/planes of the dual plane intake to share air, effectively increasing plenum volume and helping high RPM operation. Open N2O plate will also do this but maybe too much and reduce lower rpm velocity. A carb may care but maybe not EFI?

I think nitrous plate above is not really an option given the obstruction the power cone provides.

Not sure my SOTP testing can tell one case from another. Dakota digital dash has some 1/4 mile logging, but not sure how repeatable the results will be.
 

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Logs do not have to be intensive or high-effort. Look at the data channels your system logs, and select which data streams will give you best indicators of improved or reduced performance. It could include time of identical runs, rpmDOT (rate of RPM increase) or other data or combinations of data. Plan and run your tests to maximize that data, then read it for answers. That is diagnostic tuning. :cool:
 

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bump...
Hoping Scotty can comment on this

PSIG makes a great point about comparing the order and logging results.
Running the NOX plate above the jomar is asking for distribution issues during NOX operation imo.

Adding the plate is going to eliminate some lower speed torque, throttled torque and response as most open spacers do but compromises are common in our hobby.







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Discussion Starter · #8 ·
I enjoy pondering engine and hot rodding theory. Wish I had a dyno... I helped decommissioned an old water break style one that is in pieces at my neighbors now. It was used for air cooled VW stuff not sure it has capacity for a BBF, nitrous or not.

At this time I'm considering just running the plate. The spray bar runs in same direction as the plenum divider. So the gap or leakage between the sides is really not that much, perhaps similar to the power cone.
 
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