GSXR throttle bodies question

[InsanityInc]

Are the throttle bodies from the GSXR 600/750/1000 all physically the same?

Also, what is the diameter of the throttle bodies?

[grip_racer]

from what i've seen they are.

im not sure about the inner diameter though.

you thinking of hacking up your intake manifold and putting some on? after j-z's post, i think the project is well worth it. im buying some parts tomorrow.

[InsanityInc]

yeah, but I've got a bit different of an idea to go about it. I want to keep a plenum and a MAF setup, but can't think of a good lasting way to attach the TBs to the stock plenum, nor a way to support the plenum with rubber couplings, so i'm going to build a plenum and some short runners to couple onto the TBs out of some ABS piping and attach my filter and MAF to that. So I wanted to know what size ABS to buy.

[PandaS14]

600's are smaller. 01' and up 750's and 1000's are the same ID of 42mm. I believe the castings are the same, but not completely sure on that. The spacing of the TB's is also identical between the 750's and 1000's.

[SSS]

yeah, but I've got a bit different of an idea to go about it. I want to keep a plenum and a MAF setup, but can't think of a good lasting way to attach the TBs to the stock plenum, nor a way to support the plenum with rubber couplings, so i'm going to build a plenum and some short runners to couple onto the TBs out of some ABS piping and attach my filter and MAF to that. So I wanted to know what size ABS to buy.

The way i am doing mine, first starting from the head side is:- flanges welded to the cut lower manifold to bolt the ITB's up- silicon hose couplers to attach the ITB's to the new plenum i'm fabricating; this was how it was done on a s/c'd M3 to retain the stock ITB's. There will be short bits of pipe from the plenum base plate which will be pushed in as far as posibble to ensure a leak free seal.

BTW, you want the 1000 ITB's, the 750's are smaller.

[InsanityInc]

600's are smaller. 01' and up 750's and 1000's are the same ID of 42mm. I believe the castings are the same, but not completely sure on that. The spacing of the TB's is also identical between the 750's and 1000's.

So what's the outer diameter? Pretty close to 2"?

[InsanityInc]

The way i am doing mine, first starting from the head side is:- flanges welded to the cut lower manifold to bolt the ITB's up- silicon hose couplers to attach the ITB's to the new plenum i'm fabricating; this was how it was done on a s/c'd M3 to retain the stock ITB's. There will be short bits of pipe from the plenum base plate which will be pushed in as far as posibble to ensure a leak free seal.

BTW, you want the 1000 ITB's, the 750's are smaller.

I'm not really sure what you mean by the part about attaching the ITBs to the plenum, could you go into a bit more detail?

[deviousKA]

The 750's are the same size as the 1000's. Throttle plates, and ID/OD of both are identical. The 600's are small, i think 38mm compared to 750/1000 ~42/43 ish mm. Earlier than 2001 are different and they are all smaller, just like PandaS14 mentioned. I have the '02 750cc version on my setup so i am sure.

The O.D. of the coupled side on the 750/1000 are a bit under 50mm/2", I forget now what it is but the same as 1 1/2" conduit tubing O.D.

I discussed welding the throttles to my manifold with 3 professional welders long ago, none of them would dare try it. The suzuki throttles are a very thin casting, and is a "dirty" alloy. The alloy can be welded, but most definately will warp the casting which is very bad considering the necessary tolerance of the plate fit. No one really asked this but i figured id throw it out there.

The absolute best way to go about coupling the throttles to the manifold would be an o-ring sealed fit. This would require tons of work and considering CNC cost and all, would push the affordability factor out of realm. You would be better off going with different throttles if it came to this.

edit: I had some 750 and some 600 stacks laying around so i took this pic, 750 is on the right.

[InsanityInc]

How do you think my idea of coupling the throttles onto some ABS tubing will work?

[AmoebAssassin]

I wouldnt use ABS tubing for a manifold...things get awfully hot under your hood, and plastics lose considerable strength when heated, much more so than metals..

[InsanityInc]

I wouldnt use ABS tubing for a manifold...things get awfully hot under your hood, and plastics lose considerable strength when heated, much more so than metals..

Many new intake manifolds are actually made out of high strength plastics. I'm not sure of the specific type, but apparently ABS can withstand temperatures of 80C and be fine.

[deviousKA]

ABS as in hard plastic? I dont know how you could go about doing that, unless you find some that will fit over the throttles really tight (assume thats your plan) and then clamp them. You will still have to attach them to your manifold on the other end and will run into the same problems i would think. With something like this your I.D. wont match inside the runner and would be difficult to get nice and smooth, most likely you would have to transition with a reverse taper.

have you seen the oem couplers? They are a cast rubberish/plastic part that is flanged on one end. If you want to see what they look like, just search for gsxr cylinder heads on ebay, most of the time people leave them on the heads. With these you could simply make your aluminum manifold with a flat flange. I thought about doing something like this but never got around to getting a set, I may in the future with some other system.

The silicone/rubber straight up coupler really isnt that bad, you just have to support the throttles so that they do not move independent of the manifold (their only function being to seal, not to hold any weight). Thats how i ended up doing it and it works great. On mine I have the custom made manifold of course, and a bracket that pulls the throttles directly to the flange. Only problem is making it look clean, which takes time.



Thats how I did it on that one single cam. I have the '02 throttles which have those 3 beams that attach the throttles together. My 2 part bracket has a steel part which attaches to my flange and bolts to the head (bolts not shown) and a thick aluminum bracket that is precision fit so that the "beams" slide thru. It is also made so that my throttle linkage is in between. Works great, the throttles are held directly to the flange and the couplers are holding nothing. Thats a little over simplified, It took some time to design and make all the parts.

You could do something similar on the dual cam, but using a stock manifold as a base would make it tricky. Start from scratch that way all the angles are easier to work with.

[InsanityInc]

I could either clamp them really tight or just use couplers on both sides. My idea was to use the stock upper manifold with cut runners, couple the TBs onto the runners, then couple the TBs onto a custom made plenum that was made of ABS, so it would all be very lightweight as to not put any stress on the TBs. I figure I could cap off one end of the plenum and cut a hole for the IACV and just plug my intake pipe/maf/filter onto the other end.

Basically to make the plenum I would take a 3" ABS pipe and 4 pieces of 2" ABS pipe. Then I'd use JBweld or something to make it like a manifold with reealy short runners.

[SSS]

insanity, where devious has his velocity stacks, i would have a short section of pipe for each throttle that is welded to a base which forms the base of the plenum. Think the reverse of how the throttles are attached to the lower manifold to the head; that's what i'm doing for my plenum.

[InsanityInc]

insanity, where devious has his velocity stacks, i would have a short section of pipe for each throttle that is welded to a base which forms the base of the plenum. Think the reverse of how the throttles are attached to the lower manifold to the head; that's what i'm doing for my plenum.

But how are you attaching it to the throttle bodies, that's what I'm wondering. Also, since you have the TBs attached to the runners by a rubber coupler, what's supporting the weight of the stock plenum?

[SSS]

The ITB's will be attached to the runners by flanges which bolt together. The new, custom fabricated plenum (read: no stock plenum in sight) is attached to the ITB's via the silicon couplers. I saw this method used on a s/c'd M3.

[InsanityInc]

I'm just not seeing how that's going to support the plenum.

Also, I went to lowes and found some 3/1.5/3 inch ABS T pipes, so I should be able to rig up a plenum that attaches to the TBs pretty easily. My biggest problems are how to block off the other side of the plenum that my MAF and filter don't go onto and how to hook up the idle valve since I thought about it and it has to hook up behind the throttle bodies.

[SSS]

I'm just not seeing how that's going to support the plenum.

Via a bracket that attaches to where the OEM manifold support bracket is currently.

[cyrus240sx]

i have a quick question devious... wheres the fuel injectors on your single cam setup? im not seeing them.....

[deviousKA]

They are on the underside

[j-z]

i really need to get yall some pics of my setup posted up. the way my plenum is made is i have little short pieces of aluminum tubing attatched to the back side of the plenum, and i have them coupled to my throttle bodies. by the way, i have 700 miles on my setup now, and 600 without having to even touch the damn things. i really need some cams bad, but she still pulls hard all the way to right before the rev limiter hits. my right rear tires is now bald from having so much fun with these things on now. i have to get a new tire, and a vlsd now.