GSXR 600 ITB/EFI project.

[ericheath]

I don't mean to toot my own horn here....

I'm tune deaf.

[MegaDan]

My 1uz and 2jz reference was also for ITB's, which btw the 2jz-ge makes 220hp and the 1uz-fe (first gen) 250hp in stock trim. Neither engine I mentioned made stock power anywhere near the stock peak RPM points either. Said 1uz is currently in a friends Corolla drift car and makes over 380whp at 8100rpm. said 2jz was in a previous project of mine and was pushing 260whp at 7800rpm. Both engines - head work, cams, higher compression, etc etc. Not stock lol

Since you brought up a single TB 2jzgte - The stock butterfly is 65mm yes, and most guys for performance street applications upgrade to 75-80mm, with the extreme performance vehicles running 90mm. Boosted applications are a different animal though.

That site you linked is probably fairly accurate if your main goal was strong streetable performance, leaning heavily toward daily driver status with a strong low end and mid range powerband. I would hesitate to even run a 25mm throttle body on one of these engines if that was the case, as did Honda, who chose a venturi size and throttle butterfly bigger than that themselves.

I'm not saying you or that site is necessarily wrong, but that my aim and experience is just in a different school of thought, plus there are a lot of other factors that come in to play. Jenvy Dynamics actually lays it out well and fairly straight forward. http://www.jenvey.co.uk/faq/general-faq

Besides, I already stated that the throttle was a bit big for the current application. Never denied it. I have other plans in the future where they will come into their own. Especially if I can pick up another engine to build on the side.

[MegaDan]

So with the carbs off, I figured I could see what I could make work.

With the GL1000 intake runners the following items are noteworthy.

1. The lower bracing where a long bolt passes through on the GSXR holds them all together interferes with the water crossover for cylinder 1 a tiny bit but clears 3. This is mirrored for the opposite bank as well. However, even if they both cleared, said pipe is just barely in the way so no bolt and/or spacer can be used to take up the gap. That said, the tops of the bodies have two points that they can be braced together.

2. A fuel rail could be made that would clear the frame rails, but it would be pretty close.

3. There is plenty of space for velocity stacks and filters, but the width of the bell or air filter will be limited on the front two cylinders. I don't see this really being an issue, bit it's a potential problem.

4. If I were to stick with 1000 intake runners, it would be the most ideal to make the factory plenum and linkage work as it would prevent/resolve a few of these issues.

That said, I am going to try and track down a set of 1200 carb intake runners and test to see if the increased angle resolves most of the clearance problems, and if the stacks/filters sit up inside the false tank a little more.

[MegaDan]

A few more pictures.

[ericheath]

1200 will clear the pipes, but 1200 carbs are considerably smaller by quite a bit. They can be drilled wider and will seal as I did it with v65 carbs which are about the same outlet diameter as 77 carbs. The other potential problem you may have is the fuel rail may get close to the frame. A few years back someone attempted this, but I think he set the TB's straight up and down like Weber downdrafts. I don't recall if came to fruition or not. Try searching using just gsxr for it.

[Sugs]

[MegaDan]

1200 will clear the pipes, but 1200 carbs are considerably smaller by quite a bit. They can be drilled wider and will seal as I did it with v65 carbs which are about the same outlet diameter as 77 carbs. The other potential problem you may have is the fuel rail may get close to the frame. A few years back someone attempted this, but I think he set the TB's straight up and down like Weber downdrafts. I don't recall if came to fruition or not. Try searching using just gsxr for it.

From everything I have seen of the 1200 Carb intake runners they would give everything currently a little tight on the clearance spectrum just a bit more room. Obviously I won't know for sure until I find a cheap set to experiment with, but as you note they are sure to create other/new challenges to deal with.

Other smaller issues to overcome include the linkage itself. If the factory plenum and throttle cam is made to work, then little things like the throttle pull on the bodies is 180 degrees out. A part of me is considering taking the easy way out for now and making a 1200 EFI setup work, and then toying with this setup on the side. Mainly because my time is limited to work on projects.

[robin1731]

Without really looking wouldn't the linkage be similar to the downdraft weber setup?

.

[MegaDan]

Possibly, but I have never had a good look at the downdraft weber setup to give a yes or no on that one. If anybody has a good picture of that setup I'd be interested to see it.

[robin1731]

Started out looking in shop talk on out site.

http://www.ngwclub.com/gallery3/index.p ... s/hmratbam

[ericheath]

Here's an old post which was well on its way similar to yours. Unfortunately the pics are gone and it dropped by the way side. http://www.ngwclub.com/forum/viewtopic. ... s&start=60

[MegaDan]

Started out looking in shop talk on out site.

http://www.ngwclub.com/gallery3/index.p ... s/hmratbam

Yea, I ran into those and a few others. I was actually considering something just like that before I even saw this, so I think I may be on the right track. I even have a second plenum I picked up for cheap I can borrow the throttle cam from. I originally wanted to use the GSXR cam and cable brackets, but I think this may be a lot easier to make work.

What I think I may do is go buy a flat board or sheet of PVC/Metal and make a mount/template (false block to keep spacing) that I can do setup and fabrication work on while being able to toodle around on the carbs in the meantime. I have some 1200 intakes on the way, and they should be here Friday. Once they arrive I will do a test fit just like this one to see if everything clears better. If they do, then I am definitely going to stick with this. I then just need to find some sort of boot or other way to ensure the fuel injectors are waterproofed. It's always the little details on stuff like this that overwhelms my brain. I just need to take it 1 thing at a time.

Currently on a search for carb boots that will fit the throttle bodies and the 1200 intakes. Does anybody happen to know the needed inner diameter for the 1200 intake side?

Here's an old post which was well on its way similar to yours. Unfortunately the pics are gone and it dropped by the way side. http://www.ngwclub.com/forum/viewtopic. ... s&start=60

Gave up on it, or just got sidetracked?

[MegaDan]

As a side note, I picked up a second set of throttle bodies for $35. Never hurts to have spares, right?

Speaking of which, if anybody is interested, Here's a set for a pretty good price as well.
http://www.ebay.com/itm/like/1623358972 ... noapp=true

[MegaDan]

No photos yet, but I got the 1200 runners in. I never realized there was this big of a difference in the port sizes between the 1000 and 1200. The manifold o-ring on the 1200 runner is just about the same I.D. as the port on the 75 1000 head. I am fairly certain that It can work, but I am not too sure how well those O-rings will seal or hold up. The smaller diameter of the runners doesn't bother me as much, because what they lost in diameter they make up for in less bends, a shorter length, and a better angle so for all I know the resistance through the runners may be close to the same.

I need to figure out some sort of carb boot that will mate the 1200 runners to the throttle bodies. Way too small of a diameter to fit the OD of the throttle bodies themselves. My little "hold it up to the runner bolted to the head" mockup shows that everything will clear for the most part, but the carb boot length will determine if the lower brace points still interfere with part of the crossover pipe on the cooling system. It raised it up, at an angle, but also moved them back toward the larger flange end of the system and may still interfere. I am sure I can work around it in either case. Fuel rail clearance will definitely not be a problem.

[ericheath]

A hole saw will work, better than you'd think, to enlarge the 1200 intake to fit 1000 carbs.