1G Throttle Body - How Restrictive???

[BLK1g-gte]

Just wondering if anyone knows how restrictive the 1G throttle body is? I have noticed a few 250 + rwkw 1g are useing a XF throttle body so i was after some more info for this conversion and how much of hurdle the standard one is at these power levers?

Thanks

[Duk]

What size are they?
I've seen RB20s that make 250RWKW with their standard 60mm TB.

[BLK1g-gte]

Its 60 mm inner radius. Correct me if i am wrong people. That good to know but that that power level is possible on 60mm

[web]

It's a matter of flow, not power.

If you have extensive headwork, cams, etc... flow increases and you might run into a TB size limitation.

If you turn up the boost, at the throttle body only the pressure increases, not flow by volume, and you're much less likely to run into TB restriction.

But don't take my word for it, hook up gauges and measure if there's any pressure drop across the TB. If not, your money is better spent elsewhere.

[J0RD0]

i think the 1g throttle was 55ml from memory. The 1g is not a powerhouse so unless your going big cams/turbo and other stuff not really worth it. I also got told the bigger the throttle the less driveability you'll have with throttle response

[web]

Agree... a bigger throttle plate often FEELS quicker because you only have to crack it open a bit to effectively have WOT.
*Feels* like better throttle response, but the same feel would be achieved by a smaller cable wheel on the stock TB.

Actually adding power is only possible if the stock TB really is a restriction at WOT. Which is hard to believe - isn't it bigger than the stock IC hardpipe leading to it ?

[RyleyMA61]

Web is spot on... smaller orifices generally mean higher air velocities, which is higher response. one reason why some people don't port turbo manifolds- get the air moving faster and hence spool quicker

you have to consider your system as a whole, and whether the throttle poses a restriction. do you want outright power? or driveability/throttle response?

I know of someone with a turbo four, and the acutally car make more power and a lot more midrange torque with the standard plenum than a big custom one.

[BLK1g-gte]

Thanks for the info. The engine has got decent size custom cams and cam gears and the turbo are custom Blitz BAG units with 1JZ internals. I am still using the stock two pipes so yes you are right there isn't much to be gained if I increase the throttle body unless I increase the piping as well. The reason I asked is I seen a lot of other people swap to a bigger XF ford throttle body and wanted to know the main reason why.
The only other restriction would be the turbo pipe that joins both turbo's to one pipe and then to the intercooler. There is no AFM so no restriction there. I think i will leave it as is and see what happens... I want to utilise a stock looking engine bay as far as the top intercooler pipes are considered. I am just looking for restrictions that may creep up.

[Kedderz]

I swapped to the ford throttle body for easy idle control with the microtech. It can control the ford unit with just one output where as the stock toyota one needs 4 inputs to drive it.

[BLK1g-gte]

Hi Kedders i will be running a Mictortech lt10 as well and that swap makes good sence. What is involved to do the swap and can the stock piping be reused???

[Kedderz]

No the stock inlet piping cannot be reused, you need a new pipe from your intercooler to throttle body.

[ddeane]

Gidday

If I recall the ED throttle body that I am using is 65mm (If I recall the EF one does not provide the Idle control as part of the TB). While it is a bolt up you have to machine the inlet manifold out to 65mm and make a blanking plate for the old idle control - I cleaned out the inside of the maniflod at the same time. As well as easier idle control for the microtech it also provides you with the ford TPS. Remember to get the plug and piece of the wiring loom from the ford for the idle control and the tps. You will also have to change the linkages but that is no great problem.

I am not aware that I experienced any adverse effects from the large Throttle body, but then again it was not a huge increase.

Cheers Craig