I am aware of LTx intakes where the plenum and runners were heavily modified for high RPM use. Does anyone know of someone that has added a second TB to a production intake?

I’m currently finishing a dual throttle body intake designed to increase plenum volume, raise plenum pressure and eliminate the LTx intake distribution problems. This is for a bracket 383LT1 ~ 600 HP.


After reading the “Single Plane Tuning” thread, I’m getting concerned about tuning issues. I’m looking for help with a base line tune-up.

 

it would be cool to mount a stock throttlebody at each end of the LT1 intake.... in terms of equal distribution to the front/rear cylinders it would work nice.
what a packaging nightmare that would be, eh?

 

What I did was mount the second TB on top of the existing one. The top one feeds the rear four cylinders.

 

What effect would the unequal length runners have on the motor.
It seems to me that the difference in and of itself would cause some additional tuning issues.

 

Do you mean the plenum length? Actually it's all one plenum like a dual plane.

 

Without seeing your design I just assumed after you said that you put the 2nd throttlebody on top of the other that you made it look like this.

.........--------------------------------\
TB XXXXXXXXXXXXXXXXXXXXXXXXXXX \
.........------------------| XXXXXXXXXXX \
TB XXXXXXXXXXXXXXXX| XXXXXXXXXXX \
......... ---------------------------------- \
.....................OO................... OO .............

Obviously it's more complex than that but assuming that the pic comes through you get my point.

X is plenum area.

 

like this, it's all one plenum, the idea is to make sure each runner sees the same pressure.

.........--------------------------------\
TB XXXXXXXXXXXXXXXXXXXXXXXXXXX \
.........------------------XXXXXXXXXXXXXX \
TB XXXXXXXXXXXXXXXXXXXXXXXXXXXX \
......... ---------------------------------- \
.....................OO................... OO .............

 

I was thinking that it'd be interesting to move 2 TBs to the top of the plenum facing up. They would have to be inline, but that could look cool and possibly perform very well if you could set up the linkage and everything.

How would you do the linkage in your dual TB intake? Hook them so they both open at the same rate and everything, or make them progressive?

 

We are setting this up with two throttle cables so the both open at the same rate. It's for a purpose built race car so the power band is very narrow and high. With one TB on top of the other it would be easy to tie the two together with linkage.

Here's a picture of it mocked up before welding. The original TB is missing but will go in the stock location.

 

What is the projected power band for that intake?

 

The car is running now with a ported LT1 intake. Best times has been in 9.9s, I think the RPM range is ~ 5500 - 7200.

After reading about Turbo6's car I'm starting to wonder is this will help.

 

very cool looking and I betcha it'd fit under my stock hood

I'm guessing that you started with a 93 intake that lacks the corssover?

I've got an intake that I machined most of the top off that this could be done to.

Obviously this is a speed density car since it would be a total PITA trying to get 2 MAFs to work.

 

Depending on how the ducting is constructed (if/where it splits), there could be one MAF.

 

The intake is 3.5” taller than stock. It presently retains the production
fuel cross over, we are considering adding a fuel outlet to each rail
eliminating the crossover. No MAF, one TPS and one MAP will be utilized.

 

i did see one many years ago like back in 1999 on here with one in the front and one in the back but good luck finding it