Upgrading OEM Throttle Body

[Noz]

Has anyone ever increased the bore size and butterfly flap?

 

I know throttle body options are limited for people who want a plug and play installation.

 

[Chris Wilson]

I have done butterfly diameter upgrades on RB26DETT Skyline multi throttle bodies. In fact the ones on my own engine have enlarged butterflies and I have a set for sale on the shelf. What pressure drop are you seeing across the stock throttle body though?

[inazone]

How much of a difference would this make to a BPU supra?

 

 

[Chris Wilson]

I doubt it would make any noticeable difference at all. Two £10 pressure gauges a bit of small bore rubber hose, and a threaded nipple will tell you. My own measurements show minimal, absolutely MINIMAL pressure drop. Far better places to spend money and time.

[Tricky-Ricky]

Hows this? I have allays thought that intake and throttle size, only becomes a restriction when N/A, as soon as there is a positive pressure IE Boosted, the intake pipe/throttle body size is only a restriction when the boost/flow exceeds a certain amount.

 

IE pressurised can flow far more then non pressurised in the same pipe size/dia, before the size becomes a restriction.

Edited July 4, 2016 by Tricky-Ricky (see edit history)

[Chris Wilson]

Err, proof read and edit that please Tricky-Ricky

[Noz]

If the pressure isn't increased, but the bottle neck areas are increased, then surely flow will increase. Thus easier to hit bhp figures with the same psi.

 

Perhaps a tweak for boost controller would be more power, but perhaps someone want's to increase power without doing that route.

 

Surely the pressure test is a measure for the quality of the seal, and setting the standard to meet if machining it out.

[Wez]

Sounds like a lot of work for little gain, would be easier / cheaper to fit larger aftermarket unit

[Noz]

So got some material for a larger butterfly valve. As there isn't much material I expect I song be removing much material from the bore.

 

However. NA owners don't have access to any upgrades. So it'll be better than nothing.

 

How many NA owners have never changed anything? Most I expect.

 

Even 5hp overall with polished intake be better than nothing. I remember looking for plug and play mods for my own GE engine before I had a good job able to fund expensive boost.

[Chris Wilson]

Stroker crank, rods and pistons would probably be the best bang per buck on a GE engine, but still costly compared to a turbo transplant, as you still need cams and a mappable ECU

[Noz]

The frequency of stroker kits on NA engines shows how affordable they are sadly.

 

Shame there isn't an upgraded intake and throttle setup which works and gives NA owners a small option, even for low hp gains.

[Noz]

So, finally got a jig made. Got the throttle body de assembled, going to give it a go next week regarding boring. Will be aiming for 2mm.

 

Be interesting to see how it works out on a Dyno.

 

Compared to boost, it's minor. But be great to just get a tiny bit more from the throttle body regarding flow, as NA owners don't have the funds for huge engine changes.