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Discussion Starter #1
Has anyone upgraded their throttle body yet? If so, from what company? Who has a larger throttle body available?

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JRMSR :shiftdrive:
 

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There are a few larger throttle bodies out there, but it is really questionable about the gains to be made for the price. Unless there is a significant increase in diameter from stock you aren't going to see the gains. Personally, I would address the plenum before the throttle body.
 

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Discussion Starter #3
[/quote]

I presume that your refering to the upper plenum, correct! I have an o5 35th Aniversery Edition so the lower is as good as it's going to get, unless I go to the new Kinetix's Manifold. Throttle bodies aren't that expensive, nor are rebores. There are generally core charges involved and gains are respectively modest, in the 5% area. If you can't get increased airflow in, you restrict to pump so to speak, and the output is also restricted. CAI, Throttle Body, Upper Plenum and the the Lower. All tie into the same thing. Getting more air in creates more output from the pump!! That's all an engine is anyway, is a big pump.

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JRMSR :shiftdrive:
 

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Considering that you have an 05, then you are ahead of the game. I guess with that in mind, you will definately need to address other areas. You can still get a new upper plenum that can help you out and a CAI (cold air intake) would also help you out. As for the throttle body, I would do that last. I have seen some dyno posts where they have shown a gain of 4-5 hp, you can get that much just with a CAI alone. While it seems like you are content on getting a new larger throttle body, to me it is not worth it until you address other areas first to find your easier gains.
 

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I have yet to see solid evidence that the upgraded throttle bodies help our car..

I have seen pictures of individual throttle bodies, but god only knows how much that would cost and if you would see any gains..

I am not even sure if you can get the individual throttle bodies i have seen..

http://www.350evo.com and http://www.proflowdesign.com are the only ones selling upgraded throttle bodies (i believe 350evo has proflow do their work so they are essentially the same)
 

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Discussion Starter #8
[/quote]

So what your saying is, you got to add, "ported and polished heads, upgrade the cams or have Forced induction to see any substantial gains from a larger throttle body!? Excuse me, :rolf2: (no offense)! If you did all that your suggesting, I would hope that you had some substantial gains to begin with.

Realistically speaking, everything you've suggested will increase power output, but without getting additional air in, you will not realize the full potential of the upgrades you have just suggested. This is common hotrodding knowledge.

All I've heard so far is no one believes that it would be a worth while upgrade for the money and I might say, without concrete evidence. Who told you that your not going to see significant gains from a larger throttle body? What do you deem a significant gain, keeping in mind that I originally suggested 5% increase. Give you an example, I have an S2000 that originally gained almost 13 hp with a throttle body. Now, I know that each automobile has different power delivery characteristics but no matter how you look at it, this is a substantial gain for a bolt on.

Think about how you breath if your running or working out. Do you increase your air intake or do you breath normally. Naturally, you increase your air intake. Optimally, you must or your not going to attain your best performance, right! The same goes with a high performance engine. A throttle body controls everything in an engine. The wider the butterfly opens the more fuel and air etc.

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JRMSR :shiftdrive:
 

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From my understanding (no concrete evidence to support this either) the throttle body issue comes down to a simple issue. it is not the restrictor in the intake chain. While you are obviously correct that more air equals more power (all things being equal), it still comes down to the weakest link. If you were running 20 pounds of boost thru a 1" hose and put a 20" throttle body inline with the hose how much difference would be made? It is your money and more power to you if you decide to go this route. I don't think anyone would be saddened if you installed a new tb and netted loads of horsepower.
 

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More air + the same amount of fuel = lean. Seen it on the dyno for my car.

TB might be a good mod in conjunction with SAFC-II, reflash, Piggyback ECU. Otherwise, you might just be putting the cart before the horsepower.
 

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[/quote]


This is closer to what I meant. To date the only guys that I've seen have any "real" gain from the TB upgrade have been those with Highly Moddified NA cars (heads & cams) or the guys with FI. For those of us with fewer NA mods they TB upgrade has yet to provide much of a gain. (This could also be due to the ECU not allowing the TB to open 100% as well).
 

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Fillup nailed the issue dead on.

Sure, and large TB can give substantial gains on some cars. The 350Z is just not one of them. The reason is that our TB is decently sized to begin with and it is not a bottleneck. The real bottleneck on the intake side is the upper plenum (not so much on an 05 35th due to the new lower plenum). On the exhaust side, the real bottleneck is the cats (of course).

As for the power claims above, they are correct and their is evidence to support them. Even 350EVO only claims a small gain 4-5hp form this change.

As for the engine just being an air pump, you are largely correct. However, there is a limit to the pump. At a static air pressure, the engine can only pump so much air. If you remove all the restrictions with the hope of gaining horsepower, you reach a limit due to static air pressure. After you hit that limit, the only way to increase the CFM through the engine, and hence power, is either F/I or an increased compression ratio.

All of that being said, from experience, we are suggesting your money would be better spent elsewhere. If you plan to go F/I, then a TB would be a solid investment considering the cost.

As a side note, the TB is programmed, bored or not, to close to 90% above 5500 RPM. So, getting a larger TB before reprogramming the ECU would certainly put the cart before the horsepower.
 

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won't make a real big difference until you go fi.. even then i would change the whole plenum.
 

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More air + the same amount of fuel = lean. Seen it on the dyno for my car.

TB might be a good mod in conjunction with SAFC-II, reflash, Piggyback ECU. Otherwise, you might just be putting the cart before the horsepower.

The 350z crowd is great, you guys think a reflash is needed after you change oil brands. I like this as I tune cars for a living. I am gonna cost myself money here by helping you out.

On and airflow based fuel managment setup(stock 350z) the airflow sensor measures air coming into the engine and then calculates injector pulse width that is appropriate to achieve the proper air fuel ratio. This is how the engine can hit an accurate air fuel ratio in Denver and phoenix with the same programing.

If it had a calculated airflow like a speed density system(such as haltech, aem, or proefi) then I could see needing a tune from such a modification because airflow is calculated off of engine efficiency and rpm/intake absolute pressure.

That being said I would like a larger throttle body for my 350z, It has and intake, cams, and 2 58mm turbos I think that warrents the desire for a larger throttle body. I would like one with a mechanical stop adjustment as well.
 

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Why did you bump a 5 year old thread to bemoan your customers, few of whom still post here?

Also, while your statement is true that most intake mods probably don't need a retune, a larger throttle body is probably the most sensitive part to increased diameter (mass flow equals density * area * velocity). A change in throttle body area will need at least it's signal remapped.

~Pat
 

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Why did you bump a 5 year old thread to bemoan your customers, few of whom still post here?

Also, while your statement is true that most intake mods probably don't need a retune, a larger throttle body is probably the most sensitive part to increased diameter (mass flow equals density * area * velocity). A change in throttle body area will need at least it's signal remapped.

~Pat

The area where the air is metered remains the same. More air less air, the computer knows...

I bumped it because I want a new throttle body. Thought I would start here.
 

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Dammit, I feel like an idiot. Yah, the question was a throttle body, I was thinking MAF housing. Why do I always do that on this site. I agree with you. Just curious, which of the two is the bigger diameter? Any consideration into a trying throttle body spacer with a nice inner profile to smooth the air's deceleration into the intake manifold?

~Pat
 
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