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Discussion Starter · #1 ·
Just throwing this out there but has anyone tried swapping to a larger throttle body? I was thinking of using one offnthe Toyota V8 engines. They have units that have 65, 70, & 75mm diameter openings. Does anyone know the diameter of the stock throttle body on the 2nd gen? My search skills are coming up short with an answer.
 

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Discussion Starter · #2 ·
And of course right after I post this I find the stock throttle body opening is 55mm. So that question is answered. I don't know what gains if any this would have to the NA crowd but I think it would be a good way to increase the air flow for the turbo/SC crowd.
 

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Discussion Starter · #4 ·
Yep, it would be if I was using the stock intake. Got a little project going that will remove the stock manifold. Also answered my own question last night and discovered that a 65mm is the largest practical size I can go with and is very close to the size I need. Time for some eBay shopping now.
 

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Discussion Starter · #5 ·
Well ordered a used throttle body off a 1GR-FE 4.0L V6 engine from a Tacoma. In stock form this engine comes in configurations up to 285 hp and 289 lb·ft of torque. With what I'm planning this is within the ranges that I'll be looking at so the throttle body should flow the right amount of air through it. Once it gets here I'll start comparing it to my spare stock throttle body to make sure the electronics work the same, should since they are both made for Toyota, and getting a chance to do size and bolt hole comparisons.
 

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Discussion Starter · #8 ·
Yeah, I saw that. The RX-8 is a 70mm and will be too large. It also requires reversing the throttle position sensor contacts inside the assembly to conform to Toyota's. I'm hoping that the Tacoma one won't even have to be opened and can just plug in.
 

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Discussion Starter · #10 ·
That's what I'm hoping. While looking at the others I realized that they would be oversized for what I'm doing in terms of CFM and I'd end up with something that wouldn't idle well. And as it turned out anything past 65mm wouldn't help as there will be a restriction down the line that is at 62mm that I can open up some but not to 70mm.
 

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Discussion Starter · #12 ·
I don't know how well this would work for NA set-ups. It works out that the stock 55mm is a good for the size and power output of our engine with some headroom to spare. A little port n polish to remove the step inside the throat seemed to help when I did it, but it might have just been cleaning the throttle body too. Either way I'll try bolting this up to the stock intake and see how it goes.
 

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Discussion Starter · #13 ·
Got the throttle body yesterday.

Here it is next to a stock one.

Larger 65mm on the left, stock 55mm on the right





Biggest differences beside the obvious size.

Bolt pattern is different so if someone wanted to use this on the stock manifold it would need an adapter plate made.

The stock 55mm one has two extra vacuum attachments on it. One I've determined is for the EVAP purge solenoid, don't know on the other one yet. Simple enough to fix, just reroute them to another vacuum source or tap the new throttle body for it. The second of the vacuum attachments may actually be an input as it doesn't seem to go into the throat of the throttle body.

Last difference is the throttle plate screws, on the stock one the back of the screws have been flattened to make it impossible to remove them without damaging them. The 65mm screws on the other hand are normal and can be removed without damage. Makes it much easier to get the plate out for knife edging it.
 

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It looks like the vast majority of Toyota/Lexus vehicles use the same bolt spacing as the one on the left; looks pretty likely that there isn't going to be a direct bolt-on upgrade out there. Are you planning on making an adapter plate, or does the search continue? Also, can you measure the bolt pattern on the stock one? I'll do some research myself, but I want to make sure I'm starting with the right dimensions.

Thanks for the work so far - I love working out OEM swaps like this.
 

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Discussion Starter · #15 ·
I'll be making an adapter for this but it's not going to the stock intake manifold I've got an Eaton M62 supercharger going in that it'll be bolting to. I think for any of the larger throttle bodies to hook to the stock intake manifold it would require an adapter to be made as they all come off V6 and larger engines.

It's possible that the 2.7L 4 cylinder engine used in the Tacoma might be similar. It looks to be about 60mm in pictures but I think the bolt pattern is the same as the 65mm I've got and it doesn't have the two lines either. I'll try to get some measurements of the bolt pattern in the next day or so.

I have determined that the EVAP line is an incoming line from the charcoal canister by the gas tank. That's an easy fix as I can route it to the connecting pipe I'll have made to bolt the throttle body to the supercharger. The other connection is definitely a vacuum line as it goes directly to the intake manifold. Of course I can't find it described on any of the parts sheets I've been able to see, so what it's for is still up in the air.
 

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I looked into the 2.7L tacoma 2TR-FE, and the entire intake is "almost" a match (bolts are just slightly off) and the throttle body itself doesn't seem to be a match.

I did a little digging and it looks like the vacuum line on the stock throttle body is actually a source of vacuum, so if that's right, you'll have to replace it with another vacuum source under the hood.

Honestly I'm way more interested in what you're doing with the M62... I don't think I've ever seen one bolted up to a 2AZ, and they're plentiful in the junkyards around here.
 

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Discussion Starter · #17 ·
Finally found out what the last connection was. It's a drain pipe that was deleted for the 2011 model. There is actually a TSB to replace it on the 05-10 tC and 08-10 xB with an updated TB that does not have it. The other end can just be left open and it won't affect anything. Obviously is doesn't go into the intake manifold like I though, must just go to something next to it. This makes things easier for me.

Yeah, I'm pretty sure I'll be the first to bolt one up the a 2AZ. It only will work due to our electric power steering, the tC guys can't do it a they have a normal power steering pump. There is still a pulley where the power steering pump should be but it's just there to keep the belt in place. I'll be removing it and positioning the M62's pulley in it's place. That's why I wanted to use the Nissan Frontier version as it had a side inlet on the supercharger which will end up pointing up in my application. Also because it is a newer design than the one used on the GM 3800s. It will end up being a very stealth install as it will all be on the backside of the engine. The only part that will be out front is the heat exchanger for the air-to-water intercooler.
 

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That's awesome stuff! I have to wonder if the boost curve is close enough to the failed TRD supercharger to use the TRD ECU flash... Would save a lot of money and effort. I'm absolutely interested in following this if you want to log your work and of research.
 

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Damnit now I can't stop thinking about this. Looking a the flow charts, the M45 looks like it would work and might even be doable with very few parts.

* M45 unit with the right pulley size and bypass valve (challenging, not as widely available as the M62)
* 440cc injectors
* TRD ECU flash
* Colder spark plugs
* New belt
* Custom SC mounting bracket
* Piping for (fresh air into SC and from SC to throttle body)
* Intercooler (preferred but not technically mandatory)

The stock intake manifold could even be kept, provided there is mounting room without removing it. Granted the M45 isn't a good choice if you want a ton of power. but I'm talking about duplicating the TRD numbers at the most. The huge challenge would be finding the right mounting position and fabricating the mounting bracket(s).

Edit: looks like the M46 or M62 are supposedly mountable in any position (upside down, sideways, whatever) so there's always the option of an ugly "hood bump" and mounting it up high.
 

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Discussion Starter · #20 · (Edited)
Damnit now I can't stop thinking about this. Looking a the flow charts, the M45 looks like it would work and might even be doable with very few parts.

* M45 unit with the right pulley size and bypass valve (challenging, not as widely available as the M62)
* 440cc injectors
* TRD ECU flash
* Colder spark plugs
* New belt
* Custom SC mounting bracket
* Piping for (fresh air into SC and from SC to throttle body)
* Intercooler (preferred but not technically mandatory)

The stock intake manifold could even be kept, provided there is mounting room without removing it. Granted the M45 isn't a good choice if you want a ton of power. but I'm talking about duplicating the TRD numbers at the most. The huge challenge would be finding the right mounting position and fabricating the mounting bracket(s).

Edit: looks like the M46 or M62 are supposedly mountable in any position (upside down, sideways, whatever) so there's always the option of an ugly "hood bump" and mounting it up high.
The M62 is a better fit engine size wise as it is designed for 2.0-4.0 L engines, but yes the M45 will work if you are wanting to stay at lower boost levels.

You could mount it over the exhaust manifold, essentially placing the pulley where the TRD shaft ended. Downside is of course the heat soak. I chose to do it the way I am because I didn't want heat soak and I wanted to go for the higher power levels. There might even be enough room to fit the M45 on the back of the engine without removing the intake manifold.

The big downside to this is it can end up costing more than a basic turbo set-up with having to fabricate the parts. But you do get the power right off the line with no spool up time. And it's just plain different!
 
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