Throttle Body Talk

[kywhitelightning]

Subbed for before/after results.

Jeff

[fastfalcon94]

This is the cam thing he is talking about. This was my Q45 before I modified it.



And this is after.



I had to modify it because the cable would have wanted to run right over my rear IC pipe. There was no room so I had to move it in. I figure right now it will behave like all of the aftermarket ones which don't have a cam and give you a nice linear throttle action. When it pivots 90 degrees the throttle plate goes from fully closed to fully open. I still need to weld the cable holding bracket to the key holed washer, but I need to do some measurements of pedal travel first. It will determine how inward/outward the bracket needs to be to go from 0% to 100% throttle.

[futurevr4man]

Oh, I've never heard that called a throttle cam before. I see now. Derp.

As far as my chrome comment, I dont really mean changing the tune, I am thinking there might be some throttle control setting in chrome that relate throttle position to load or something. Idk. I haven't looked at it at all yet, so I'm talking out my butt. I'm excited to get this thing in though. I'll post pics of everything when I get it in.

[TurboSinceBirth]

I am interested in your pressure drop test as well TSB. When do you plan to start your trials?

I'll probably try swapping the throttle bodies first since I have everything for that. I don't have a 2nd map sensor or a place to wire it up yet. Since my car is still in pieces it will depend on when I get time to work on it. I've been cleaning out the garage and getting rid of some engines so I should be able to focus on my car within the next few weekends. I still have some porting left to do on the turbine housings and I'm thinking about just getting rid of the step on the exhaust manifolds since the gasket matched set needs welded up again due to the piping wall peeling out from the last weld job. I'll probably have to send my injectors out to be cleaned after sitting in ethanol for 14 months.

I'll be out of state working a month from now for 3-4 weeks so it may be after the 2nd week of June before I get much testing done depending on how work, projects, and finals go the next few weeks.

Will the s90 74mm fit the stock manifold?

It will bolt on but you can't port the stock intake manifold out big enough for the opening. The stock intake manifold is about 72mm OD on the neck. I may try welding aluminum on the outside and extrude honing it to 70mm from the flange. First, I'll just port the flange and if that produces some good gains I will try opening things up further. The 74mm s90 throttle body I would use on an aftermarket throttle body. Most people with the stock intake manifold are running vendor FMICs with 2.75" piping so the 70mm ID throttle body will be fine.

Here's the s90 70mm ID throttle body bolted up to a stock intake manifold:



You can see the gap between the 70mm inlet and the ~62mm stock flange inlet. There's only a few mm to gain after the flange so it will still neck down unless you add material to the outside and port the inside bigger.

[anyonebutme]

I'll explain throttle cam (which is a motorcycle term, forgot what the car equivalent is called). A cammed throttle is just a cable pulley that doesn't have a constant radius. The radius from where the cable touches the pulley and the center is what determines the speed in which the pulley moves. The details aren't important, just the fact that the shape of the pulley allows you to tune response.

This is a rather extreme cam where low throttle is muted and progressively gets faster:



Here are 3 cams, top is stock linear, middle has a spot around half throttle that is fast to allow quick throttle adjustment in that area, and bottom is a "faster" cam so that it's still linear but less pedal (grip) travel:



For the life of me I can't find the ones for LS and LT engines, but they used to be a very popular mod for racing.

[futurevr4man]

Thanks for the explanation, Chris!

[NOMIEZVR4]

I had a focus group yesterday and got $100+ for yapping....I bought the s90 TB. Its arriving in two weeks. I will have before/after data for you guys shortly.

Jeff...this was done specifically for you...

You said above you subbed for before/after results...so I'm helping you out buddy!!

[NOMIEZVR4]

I hope I don't run into any driveability problems...the car runs great as of now...

[TurboSinceBirth]

We need to get an Xcessive intake manifold next.

[NOMIEZVR4]

Next year..