ITB's for 1jz

[ReQuieM]

Alright this has been a plan of mine for a while and now that i'm getting to the point where i'm about to do it, i'm after so extra info and input.

The plan is the cut the flange of the end of the injector stub and weld on some piping to reshape the runners to suit the GTR skyline throttle bodies then run custom runners into a custom Plenum. Thinking the runners will be as long as I can make (lower torque peak) extending into the plenum with trumpet style ends and about maybe 5-6 litre plenum volume. I just talked to a guy at EFI Hardware and he was saying for a turbo application the GTR throttle bodies will cost me power because of the poor flow over the oversized shafts ect. and recommends using a single instead.

Pretty much I'm interested in what you guys think? Are the GTR ITB's going to rob me of power? Is the response going to be good enough to justify the lose?

Um, yeah and general thoughts?

What i aim to do? I wanna break 300rwkw on stockies. Most are gonna laugh at that but its what i'm aiming it. If i fall short i fall short but thats the goal. My mods will be more extensive then just the intake! Don't worry about that. What do i want at the end? Lots of off-the-line power, revy responsive torq'y engine thats beautiful to drive and that'll blow most crap off the road I might look at a turbo change later down the road but it will always be twins.

So yeah thats the lot, comments?

[JustCallMeOrlando]

You'd have to have a pretty bloody big TB to equal the surface area of all those throttle bodies, even considering the "oversized shafts".

That said, it's probably easier to go a single, and spend the money on a better set of turbos than the factory ones, they aren't exactly new tech.

[ReQuieM]

Understandable but I'm fabricating it all my self except maybe the linkages, I'll see how hard that is but i think i'll get some one to do that tech. So as far as cost going its not going to cost me much more then upgrading the singel throttle.

[Draven]

I've got a better question, related but proably best asked on a nissan forum - can the GTR ITBs flow 400rwkw?

[no_tofu_speed]

Didnt someone on here do it? Ed something? Looked hot.

[YLD-16L]

I've got a better question, related but proably best asked on a nissan forum - can the GTR ITBs flow 400rwkw?

A few GTRs with the stock intake (ITBs) have cracked the 400rwkw mark at Summernats the last couple of years. I think one went near 600rwkw a couple of years ago.

[RONA]

Didnt someone on here do it? Ed something? Looked hot.

that was for a NA 2jz

[ReQuieM]

Yeah that was a beautiful job! Thats where i got some of my idea from. Yeah i think it can flwo enough for 400rwkw but is that through excessive pressure?

[-GT-]

GTR ITB's don't seem to be a restriction up to the sort of power you're aiming at, or further, look at the number of big power gtrs both in japan and here running standard plenum/throttles. The point they go single seems to be up round 400rwkw, but that may have as much to do with simplicity or availability of parts when changing to an aftermarket plenum.

We're probably not the best people to ask about GTRs; i respect them but don't research them

What are you trying to do? If you're aiming for 300rwkw on stock turbos (which sounds like a big ask), i would not be spending money on something i can't see making an increase in power. If you're after response/bling/something unique by all means, do it, it would be cool to see.

Focus on what you're trying to achieve.

[Norbie]

You'd have to have a pretty bloody big TB to equal the surface area of all those throttle bodies, even considering the "oversized shafts".

But remember with a single throttle, there is never 6 cylinders drawing air at the same time - at most there will be 2 cylinders with the inlet valves open at any given point. That's why a single throttle can out-flow individual throttles even if its surface area is lower than the combined area of individual throttles.

If it was me I'd stick with a big single throttle on a custom plenum. If all you're chasing is power then this will work just as well, and frankly I can't see the throttle response being much different on a turbo engine. Yes there will be an improvement with ITB's but enough to justify the extra effort and expense? Probably not.

[chris davey]

Maybe I am too conservative but I would be going the traditional way. Big custom plenum, larger throttle body. I don’t see what you are trying to do by doing this except for being different and having bling ITB setup. Low down response is always going to be there if you are using stock turbos. There is virtually no lag anyway. If you want to make 300rwkw on stock turbos I would be getting a N2O kit as I can’t really see it being done any other way unless the dyno is seriously off.

*beaten by 3 minutes while I was typing*

[Draven]

bah, scrap all my questions.
Thought the vvti manifold was a restriction at 550bhp, but it's 650. all is sweet.

[ReQuieM]

I'm glad no body else is in a working mood this arvo! Thanx for the feed back guys.

Ok so to the first, yes i know 300rwkw is a big ask. I stated this in my first post, I dont really want to get into a discussion about it. Some will say no some will say maybe. Whatever. I'm going to get as close as i can. I've told you this so you can get an idea of my final goal power wise.

Saying that, my ultimate goal is to engineer the 1jz to its ultimate form. Again big talk i know. But i want to do this through better flow characteristics, better components but retaining certain things like the turbos. The exhust manifold will be next. Same layout but better flow equal lenght tubing individual sensors ect. So saying that I wanted the ITB's so i can effectively tune EACH cylinder for max output. So there thats the main advantage. Response is next. then was flow.

SO knowing that opinions?

I guess the way to judge the real differnce between response would to ask a skyliner thats drivin a GTS-T and a GTR. I off to the skyline forums!

[Celica RA45]

i make 20 v quads and can do a 6cylinder set in any size you wont 45mm 48mm and 50mm and up to 52 mm as these are all independent of each other its most likely easier to tune against 1 shaft going through 2 butterflies

[ReQuieM]

Pretty keen on building it my self but on the subject can you pm me with some prices of throttle bodies? Could aslo do with some advice on ITB's in general.