Staged Throttle Bodies

[Scooterwrench]

Has anyone tried to do a staged dual TB setup?
I was wondering if the drivers in the computer could run another set of injectors? The idea is to tee off the injector wires coming off the PCM to a second throttle body with a staged linkage like the Q-jet. The secondary TB would have a micro switch to apply ignition power to its injectors as the plates start to open.
The theory is to have the higher velocity for good part throttle acceleration and cruise and more air/fuel for get gone right now.
1-11/16" plates for primary,2" plates for secondary?

Yeah,I figure it's gonna require some PCM tuning!

 

[PlayingWithTBI]

The theory is to have the higher velocity for good part throttle acceleration and cruise and more air/fuel for get gone right now.
1-11/16" plates for primary,2" plates for secondary?

The EBL Flash-II can run 4 TBI Injectors with "4 injector Upgrade" ($75) IIRC. IDK about running progressive linkage/fueling though. Maybe contact [email protected] for more info?

Mind if I ask, what kind of fire breathing monster are you thinking about building with those big TBs?

 

[pressureangle]

Has anyone tried to do a staged dual TB setup?
I was wondering if the drivers in the computer could run another set of injectors? The idea is to tee off the injector wires coming off the PCM to a second throttle body with a staged linkage like the Q-jet. The secondary TB would have a micro switch to apply ignition power to its injectors as the plates start to open.
The theory is to have the higher velocity for good part throttle acceleration and cruise and more air/fuel for get gone right now.
1-11/16" plates for primary,2" plates for secondary?

Yeah,I figure it's gonna require some PCM tuning!

I had a Holley Commander 950 setup on my '68 Charger, some boat racer had Holley custom shop build a dual-4 setup. It had a second box to split the drivers; each TB was progressive, with the secondary injectors coming in at a programmable throttle position. It was complicated enough in that it was a big system and required the smallest injectors available to keep idle mixture under control with 4 injectors on all the time, but the most difficult bit was the fuel map on a narrow-band o2 system. The fuel map had to be reduced dramatically at the point the secondary injectors came online, since the pulse time could only be adjusted for all 8 injectors at once. It worked and worked well, but it has a carb on it now with a more comprehensive Electromotive port injection system rotting on the shelf.

 

[Hipster]

Your talking dual TBI? 4 barrels sit on a common plenum, multi carb setups usually run same size carbs exception being 6 pack set-up with vacuum out board carbs like a double set of vacuum secondaries still on a common plenum. Running divorced efi units on a 2 carb intake progressive linked like a q-jet ona common plenum I just see major fuel distribution issues. The back cylinders getting fed properly from the front on "primary and vice -versa. Afr's cylinder to cylinder a nightmare.

 

[Scooterwrench]

The EBL Flash-II can run 4 TBI Injectors with "4 injector Upgrade" ($75) IIRC. IDK about running progressive linkage/fueling though. Maybe contact [email protected] for more info?

Mind if I ask, what kind of fire breathing monster are you thinking about building with those big TBs?

My cammed and ported 355. I'm currently running a spreadbore,dual plane,air gap intake on it. I have a machine shop and could make an adapter for such a rig. I'm running about 400 horses now with the Q-jet.
Would a single 2" TB feed it? Or two 1-11/16 inchers? The reason for not going to a TBI manifold is the money and time invested in the heads.

 

[Schurkey]

A progressive throttle system is likely to need two throttle position sensors, and separate injector drivers so that the fuel can be metered more to the more-open throttles, and less to the less-open throttles. Otherwise the more-open "primary" throttle body will have enough fuel, and the secondary throttle body will have way too much most of the time.

Pretty sure none of the OEM computers can deal with two TPS or separate injector drivers.

When GM used double throttle bodies, they were one-barrels with one injector each, and they weren't sequential.

 

[Scooterwrench]

A progressive throttle system is likely to need two throttle position sensors, so that the fuel can be metered more to the more-open throttles, and less to the less-open throttles.

Pretty sure none of the OEM computers can deal with two TPS.

Yeah,I wondered about that too. I was thinking because both TB's would be wide open at the same time that maybe one would work. Stage the secondary so that it opens at the same rate as the secondary's of the Q-jet.
Hmm,I see the fault in it now.
I'll have to admit,this fuel injection system is kinda spoiling me,just turn the key and let the electronics do the rest.

 

[someotherguy]

When GM used double throttle bodies, they were one-barrels with one injector each, and they weren't sequential.

Yep. Good ol' (well, not so good ol') Crossfire injection.

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Richard

 

[PlayingWithTBI]

My cammed and ported 355. I'm currently running a spreadbore,dual plane,air gap intake on it. I have a machine shop and could make an adapter for such a rig. I'm running about 400 horses now with the Q-jet.
Would a single 2" TB feed it? Or two 1-11/16 inchers? The reason for not going to a TBI manifold is the money and time invested in the heads.

I'm in the process of fine tuning my BLue Print "383" (actually 377 with 4" bore X 3.75 Stroke), 10.3:1 compression, XR282HR (230/236 @ 0.050" Duration, yada, yada.yada, with 1 Bored 46mm Throttle Body (at 20 PSI) on the Edelbrock 3704 intake bored to 48mm up to 5700 RPM at ~12.3 AFR on my WBO2. I'm still breaking it in, maybe I'll try a couple hits up to 6K then.


According to Blueprint with different heads (64cc Chambers, 195 runners instead of my 170cc, 62CC chambers giving me a little more compression and probably more low end torque)

HP & Torque: 436 HP / 443 FT LBS
Compression Ratio: 10.0:1
Hypereutectic Pistons
Cast Steel Crank​

Motortrend did better with a 383 and the same cam.

GM HT383 Crate Small-Block - Engine Build - Hot Rod Magazine

Tuning GM's HT383 Crate Small-Block for 500lb-ft of torque is as easy as 1, 2, 3, 4, 5, 6. Find all the details inside Hot Rod Magazine.

www.motortrend.com

Anyway, IMHO a 2" TB and an adapter on your intake should work. YMMV

 

[Orpedcrow]

What about two sets of 4 ITBs off of a sport bike? People have been adapting single sets to little Honda cars for a long time.

Or Kinslers if you’ve got ALL the money lol

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