I have been gathering parts for a FFIM when I cam across this picture of an Is300 with a LS430 throttle body welded onto it.



It got me thinking why not slap a LS400 flange on this extra Y piece I have. If I dont like it i can still go FFIM, at least i'll have wired it in.

LS400 is shorter and I am gonna try it without that large transition pipe also, So I cut the Y-Pipe to about the right spot and made a mock up ls400 throttle body flange out of 1/4" aluminum.

I found the LS400 throttle body to be the exact same size as the Cut I made on the stock intake manifold (~ 2.75" hole for flange). Also the LS400 throttle body uses the same tps connectors and you will be able to retain cruise control, you wont have to move a cable even!!
Ill let the pics do the talking

Step 1: cut stock flange off


Step 2: cut out EGR pipe (dont have before pic, but you know the tube)


step 3: clean clean clean (stainless steel brush works best on aluminum for me)


LS400 Mock up w/ Gasket


LS400 full view (a little dirty but should do nicely)


LS400 throttle body on top of cut Y-pipe. (LS400 throttle body hole is 2.75" at the base, exact size as the Y-pipe oval hole)
When sitting the throttle body on top of the y-pipe even without the flange, you can open the TB plate fully and it wont touch anything.
Looks like a much better fit and should be zero turbulence.


This will still be much shorter overall than the sc300 stock setup which is unnecessary long.
4 bolts later I will be able to reach my spark plugs, and the tb flange wont be in the way of me removing my #2 coilpack, as it should sit above the drivers side valve cover now.

 

Reserved for welded/completed pics.

update** I had finished this a long time ago, but already installed my FFIM, so i forgot about this thread.
Part of me wishes I had tested this bad boy out when I had the stock intake still on, but I want to post it for others to see how perfect this mod came out.



Side by side view with stock intake w/ 5 speed throttle body (no trac). look at the savings in length.


This is a simple solution to keep the stock intake and have all the turbo clearance you need.
Taking off the throttle body gives you complete access to the plug valley.
Also If you make a bend in the pipe around the turbo, you can probably get cooler air temps as well.

 

Looks like a nice project. A welder could fill that, no doubt, but it will still leave a step face to catch and affect airflow. You may be able to fill extra around the lipped areas and then use a dremel to blend the step and make it less of a flow inhibitor/turbulator.

For what you will have in it, I would do what you said and just run it and see how it works. It may work quite well after all.

 

Great idea! I'm assuming cruise control is lost? I've got a FFIM flanged for the q45 ready to go but I would like to run the stock manifold to keep it simple initially. I like the idea of aiming the throttle body away from the turbine housing for clearance

 

I'm no metallurgist, but I wonder if you could solution anneal the intake to make it soft and then work that opening to a more round shape? I have read that you can anneal certain aluminum to make it dead soft and then work it to the shape you want. Then you just stick it in an oven to re-harden it.

 

thats good to know they can fill that. I think thats a great idea, have them make a thick weld and then sort of round it out with the dremel. I used the dremel to get the cut surface flat already so I'm getting pretty good with it.

I am confident even if I do nothing though to round the edges it will flow better than the stock setup with the massive egr tube smack in the midle of the opening you see. I was shocked when I got it out, that thing is quite large, and was 100% caked with thick carbon buildup.

I would not hook up the egr again after cutting it out. while its true that the gases end up in the same place without that end pipe, it wont catch the larger debris like the stock pipe that was caked through did, allowing all that to enter the engine. not very good.

Cruise control would be lost with the q45 TB unless you make linkage for it, its one of the small sacrifices you have to make at some point. I could run the ls400 throttle body I have also which would keep cruise control, but It's a little longer in length and smaller in diameter than the q45 throttle body. I really want my cold pipe to turn in much before the turbo where my distributor used to be , so as short and good as possible is the goal.

Im gonna have to google that, sounds pretty awesome to me but I would probably find a way to mess it up or make it collapse on itself with my luck.
but if I could use it to round out the front 2" only that would be sweet. maybe stick a soda can in it or something.

**edit** just did some reading apaprently annealing would be a good idea, but cast alumunim parts like our intakes don't have the same flexibility. it may still be possible, but im gonna go with the welding/smoothing route.

 

haha good work man, i get to creative..... how about cut there and run two tbs? just for shock value

 

lol, i had actually played around with that idea but have never messed around with dual throttle bodies before. I was unsure of how to make the linkage, and didn't really want to use motorcycle throttle bodies, but it would work and would definately be unique.
someone else should tackle that one..

 

Moving on to using a LS400 throttle body cause it fits better (diameter wise) and will retain cruise control. Gonna ignore the extra length.
Updated first post with pix.

 

Updated post 1 and 2 with completed pictures. came out really nice actually but I dont see it getting put on the car anytime soon.

Side by side view with stock intake w/ 5 speed throttle body (no trac). look at the savings in length.

 

You ever install this..if so pics?

 

Nope, never installed, it is sitting in my closet collecting dust since I installed a FFIM already.
It looks great though, I really wish I did get to see it in action, maybe when the FFIM comes off for polishing.

 

So does the ls400 use a bigger throttle body? Or is this just a great way to open up some room?

 

The stock throttle body is around 65mm and the ls400 is around 75mm. It is meant for a v8 so everything on it is bigger pretty much, but obviously it is much shorter than the stock one because it doesn't have the complicated IACV on built in. You can modify your intake manifold to fit a ls/sc 400 or supra iacv though to keep the IACV and get good cold starts.

 

You've peaked my interest. I'm doing NA-T

What year did the LS400 TB come out of or does it matter?