TBI on a Single Plane- Street 4x4

[RevTheory]

We've all seen the same tests for years showing basically the same results; dual plane is better to about 4,500 and then the single plane takes over. All the ones I've seen have been done with a carb. My question for you guys is is it a booster signal issue and, if so, would a high-pressure TBI like a Sniper or Terminator TBI fill that deficit in?

Do you think a single plane, either burred or textured with a 36 grit roll with a TBI could fall back to say 2,500 rpm on an upshift and take some pretty deep throttle without falling on its ass like it typically would tend to do with a carb or would I still have the problem of fuel falling out of suspension due to port speed in a wet manifold?

900HP did an old-school tunnel ram on his 383 tow rig, daily-driver and it worked great but he was port injected.

I'm talking about a maybe 10:1 383 in a Blazer with 35s and 4.56 gears, O/D trans with manual lockup, 2,500 max convertor (hopefully less stall than that). Cam probably in the 220/224 range, .565/.540 lift, tighter centers depending on how the 50* seats look. 107 or 108... maybe... ish... lol.

I just really dislike the lower runners on a Performer RPM but I may be stuck with it.

[Monzsta]

Good question.

I have an Edelbrock Pro Flow 3500 on a 383, which is just a port injected Victor Jr with a 1,000 cfm 4bbl throttlebody. The secondarys are staged like a carb. I've had some difficulty tuning the AE but I can tell you, when my tune is right, it's seamless across the board. No bog or lag, and all the torque you can ask for right off idle.

[RevTheory]

Good question.

I have an Edelbrock Pro Flow 3500 on a 383, which is just a port injected Victor Jr with a 1,000 cfm 4bbl throttlebody. The secondarys are staged like a carb. I've had some difficulty tuning the AE but I can tell you, when my tune is right, it's seamless across the board. No bog or lag, and all the torque you can ask for right off idle.

That would be fantastic if I could get the same results from a textured singe-plane/TBI. I'm getting tired of every engine I build having a #&!$@*% Performer RPM on it, lol. I just don't know if it's possible.

I'm hoping someone here has some experience with that combo.

[F-BIRD'88]

A single plane and a dual plane are going to function like they typically do wether carbed or TBI or Tuned Port Injected.. They are what they are. On a V8 the dual plane high rise works..
The Weiand Hi Ram tunnel Ram will make great power
especially when ported. Longer direct flow equal runners.
2xTBI's

[F-BIRD'88]

With any single plane and 35's yiu need to be thinkin 5.57:1 gears on this minimum. Especially with OD.
Or its going to be about as much fun as watching paint dry.

[My427stang]

I have always been amazed at the part throttle torque an EFI swap provides. Generally, they have been good running vehicles, but honestly not tuned to a knife edge before, so hard to tell.

I personally think that the combo you describe would work well, especially if you have ignition control too. A couple of things I would watch out for though would be too much intake (probably talking Streetmaster or Victor Jr here, not Super Victor) Maybe a little work on the roof of the plenum to clean up the turn, and only the minimal port work needed to keep the port moving quickly and cleanly

I wouldn't go tighter centers myself though, I would go early-ish ICL and keep centers wide enough to keep vacuum up and chamber nice and clean, you want to be pulling on that port immediately, not waiting for the exhaust to do it. My opinion only, and of course, all cam timing events matter, just talking lobe centers and ICL to make a point

[RevTheory]

427, did you swap port injection or TBI?

I'd definitely try to find a single plane with the longest runners and smallest csa that I could.

[Carnut1]

That combo in a truck with burred victor jr. will work. Been running tbi since '88. Use a big single cut burr and try a tapered four hole to an open spacer. Tip in will be very good if tune is right. Thanks, Charlie

[RevTheory]

Man, I am all over the friggin' place with this conundrum. Have any of you had a Super Vic 2925 on a bench and checked runner velocity around .550 lift?

[BOOT]

Thought I seen some had issues with TBI and dual planes, maybe it was the cam?

[Monzsta]

That combo in a truck with burred victor jr. will work. Been running tbi since '88. Use a big single cut burr and try a tapered four hole to an open spacer. Tip in will be very good if tune is right. Thanks, Charlie

Slightly off topic, but I'm intrigued by the concept of "burring". Is there a technique to it? Reason I ask is when I was porting I could achieve a pretty smooth finish with a burr. Medium speed with a loose hand and let it jump around, or what?

[Rick!]

Got any head data?
From 20 feet away, you fundamentally are describing a Vizard Hammer engine with a 400 crank.
With that cam, you will probably have over 500hp available.
I really don't know of any 500hp SBC dual plane manifolds but I'm sure folks here will correct me.
I also don't know if a dual plane will make that cam choice work. It seems to suggest a single plane manifold would be more suitable but it may move torque and hp upwards.

https://www.hotrod.com/articles/dual-pl ... mparisons/
https://www.hotrod.com/articles/19-sing ... akes-test/

The TBI vs Carb thing has already been answered, there will be fundamentally no difference in performance or fuel distribution at your power level.
I just read a test with a stout BBC where a 4500 terminator efi outperformed a 1450 CFM billet carb in back to back testing.
https://www.holley.com/blog/post/carb_v ... _the_dyno/

Like BOOT's sig states, you're overthinking it.

[RevTheory]

I'm not overthinking anything. I just wanted to see if that hole could be filled in by eliminating booster signal issues and port texture. No matter, after long conversations last night, I'm not going to be able to get around the runner length issue so I've officially scrapped the idea.

In my opinion, it's good to work some of these ideas out in your mind and with people you trust. Anyone can build cookie-cutter stuff, you know? You don't learn anything doing the same old shit time after time.

I appreciate the responses, fellas

[HDBD]

I may be out in left field but would your logic and approach open up possibilities for running a cross ram dry with port injectors and throttle bodies?

[RevTheory]

I may be out in left field but would your logic and approach open up possibilities for running a cross ram dry with port injectors and throttle bodies?

Interesting thought, for sure.