I am wondering if anyone has succefsully mounted a 90mm cable operated throttle body to a GM LS7 intake manifold. I think I remember someone mounting a NW 90mm TB to the manifold but I they had some sort cable issues. I haven't heard anything since. Well, anyone? Thanks!

 

Check with W2W. 248-589-1190
I think Kurt may be able to make some suggestions.

 

Would like to know as well.

 

I'd be interested as well. Big-inch LS1 + ported LS7 heads + LS7 intake in an F-bod sounds very good to me.

 

Be aware that you will need to do some work. My understanding is that when dyno testing was done recently with a cable TB, problems were discovered.

Specifically, the LS7 motor was not developed witha TB that opens at the bottom (as most cable TB's do). Development was done with an ETC TB (Drive by wire) which opens at the top. So, with the air coming in from the bottom, it disrupts airflow, and causes noticable power loss...

So, you'll need a TB that has the cable up top, and opens from the top.

 

What the difference between a TB than opens at the top compared to the bottom? I thought a TB was a TB... Are you saying that the TB blade opens a certain way, like the top of the blade goes forward and the bottom goes backward when giving it throttle?

 

Absolutely. The air at part throttle operation enters at the bottom of the TB, instead of up top. At WOT its immaterial as the TB is out of the way. But at part throttle my understanding is it causes flow disruption and power loss.

 

LS2/LS7 TB opens bottom side in.

 

I may have my direction wrong, as I don't have one sitting here in front of me.

Jason, perhaps if you have a second you can confirm or deny this. A cable operated TB opens the opposite of a drive by wire TB, true or false?

Do you have any knowledge of any issues when switching to a TB which opens opposite of the drive by wire TB's.

My information came from what I consider to be a reputable source, but since Katech has a long affiliation with the GM in GenIII/GenIV development, you input would always be welcome.

 

true or false? yes
A little of both


LS1 cable: top in
LS1/LS6 DBW: top in
LS2/LS7 DBW: bottom in


You were right about saying that the airflow would change if you put a cable TB on a LS7, you just said the LS2 configuration backwards.

 

Someone that knows more info needs to pipe in here. I have a TPIS 90mm throttlebody mounted on a new LS7 intake(DO A SEARCH FOR PICTURES)and I ran into little to no issues with this setup. My cable is pulling from the bottom while the blade also opens from the bottom?? Traver

 

The TBs I stated are the factory designs.

 

why would power loss matter at part throttle?
if the air was disrupted and less efficent at getting into the motor... wouldnt the be the equivelent of having the throttle closed a little more?... so you just need to push down harder on the go pedal?


the downside i see would be less efficentcy.. basicly less MPG... but at the sane powerlevels of part throttle driving where you care about MPG (like driving around town or on the hwy) does it make enough of a diff to even see in the MPG??

if not, then i dont see a issue?


or are you saying the opening of it itself(delta), not the way its sitting is causing the disruption... so you cant feather the throttle around, say a road course sweeping curve, with smooth powerflow, since the throttle movement is causing a problem??

 

Ttt

 

It looks like the problem is in the intake. The top of the throttle opening is very close to the first runners port opening. This may cause flow problems like uneven flow among the cylinders at low throttle openings with a cable drive tb. This looks like a simple problem to fix by turning the cable drive tb over and installing upside down.


Kurt

 

Thanks for the info Kurt.

Mr. Dude, as for the specific effects, I'm going to have to ask the person I spoke with for further clarification. My discussion with them made it sound like it was a fairly significant issue. But, I don't want to mis-speak, or give false information, so let me see if they can get in here and speak to the issue.

 

Here is a pic looking down the throat. You can see the #2 port location is very close(1.350) to the throttlebody mounting flange.

Kurt

 

So have you mounted a cable TB to the LS7 manifold? Sounds like you have. If you could give us some details that would be great! Thanks so much Kurt.

 

We are in the middle of mounting one now. This engine is odd as the owner needs the throttlebody on the bellhousing side. I have just finished some mods to turn the intake around, and by Monday evening I should have the TB on upside down. I am spacing the TB away from the intake to make the throttle lever operate.
We are also making a spacer to adapt the dry sump lines to AN fittings for the dyno, this will be available to buy soon. The tb spacer may also be available if the need is there for cable drive.


Kurt

 

Got an update.

The info is this...

On the dyno at part throttle operation airflow is disrupted when the throttle is opened up with a conventional cable operate throttle. The resulting disruption causes and I quote "a major loss of torque". How major that is, I don't yet know. I'm going to have to get on the phone and see what hard numbers the folks have on it. It should also be noted that at WOT there is no disruption to airflow, and no loss of power.