Throttle body choices

[Max]

Hi

Looking at upgrading my TB as I upgrade my Intake mani

I know the Q45 TB is 90mm OD but the intake mani I have doesn't have that flange, so what I want to know:

What is the size of a Spec R TB
Is the Spec S any bigger than a Spec R TB?
Can I bore out mine
or swap on a G20 if I can find one.
Or any other fairly simple bolt on jobs

Max

 

[Auss15]

The most popular is the 76mm NA S14 throttle body. Its a straight swap but you will need a retune

 

[Max]

By 76mm for the S14 NA is that the outer diameter?

I'll have to keep my eye out to save me getting a G20 from Stateside.

I'll defo need a re-tune with what I have in the pipeline! I'll actually be going standalone and VVL

 

[spoonman]

60mm is the inside diameter of the NA TB's

Putting a 60mm on a stock cam/turbo will just reduce low down responce and wont do anything noticeable at the high end, (reason why nissan put the 50mm on the turbo setups)

rough guide using tomei & garett stuff just match everything to suit everything else.

stockTB - stock cams - stock T28 300hp
60mm - 256 - 260cam - gt2871 400hp
70mm - 260 - 270cam - gt30 500hp thinking about removing VVL from here as you will be smashing valves on pistons
80mm plus - 280 plus - gt47plus 600hp plus after this the SR will last about a month, to expensive to maintain this kind of power

next step..... get an RB/2J

 

[Max]

Ok, so stay standard for now then. I'll get a 60mm or so TB if/when I change turbo.

I'm going to try for a MMIC (mid mount intercooler) setup to keep piping as short as possible, just didn't want to overly restrict the flow anywhere. MMIC looks pretty much as akward as sorting out piping and mounting for my Greddy WMIC that has a bodge load of pipes, and was previously mounted that way.

 

[spoonman]

MMIC is a good idea, most people put them in upsidedown so you dont have to fluff around too much with the piping, crisp as responce, its friggin awsome. Invest in a good electric fan set up if you do this as the factory stuff might not fit depending on your intercooler/rad size, the shroud will def have to go

 

[Adam L]

You may want to check your inlet manifold is matched to the throttle body you choose as with some of them they keep the stock bore size. The Greddy short port is a key example as its a much better design.flow wise but only has a 60mm throat for the throttle body mounting. Most people go for the 70mm N15 throttle body but they're ridiculous money.

 

[Max]

http://forum.s15oc.com/attachment.php?attachmentid=935&d=1358518711[IMG]
The plenum is in that pic. Looks weird as it bolts into the VE inlet runners which are very short and pretty much straight.
It has the standard TB bolt layout, but the actual throat is about 70mm so can take a larger TB no problem :) I could have chosen to have the Q45 flange instead but thought it was total overkill. A Q45 TB has just come up for sale on SXOC for £100 though!

 

[Max]

Update, been to garage-d today to drop off a gearbox and talked to Julian about the VVL build, TBs and flow. A small step up to a 60mm TB should be beneficial for me. Unfortunately he had no S14 NA or S13 TBs but plenty of RB ones. In the end got a RB20 one.
Suffice to say that the assembly that actuates the valve, i.e where the cable goes is on the opposite side, but as it is a custom plenum etc setup anyway so not a problem.

 

[spoonman]

suppose i could of told you that i have two S14 60mm TB sitting in my shed............

 

[Max]

bummer, well If the RB one is an issue I know who to PM

 

[Auss15]

And are they flowing more air into your shed....

 

[spoonman]

And are they flowing more air into your shed....

Yes they are skippy, yes they are

 

[Max]

Well I see it as £40 for one less possible source of restriction (at full throttle anyway) on a build that is costing significantly more, do it once do it properly and all. This way, the only bottle neck is the turbo itself