jclofty47

OK. So you think doing the TB port is worthwhile? I know that a clean plenum is definitely gonna help, or at least give me back some lost HP.

jclofty47

This was a CA truck when I got it, now it's a VA truck and will stay as such. I have many mods, some minor, some major, all beneficial, to come over the next few months. I will make a MOD thread when I finally start doing these things. It will be an ongoing project. And much later, perhaps in a year or 2, I'll do a 1JZ or 2JZ swap. For right now, I'm happy bouncing ideas off of my fellow Yotatechs and my buddy Rob and my brother-in-law... They're Nissan guys, but they're alright. So many thoughts and ideas, it's hard to keep them straight in my head. Gotta put em somewhere... and like my farts, most of my ideas stink pretty bad, but everyone loves their own brand, so to speak. Therefore, I need someone to tell me when my ideas stink, lol. Not asking anyone to smell my farts, that would just be wrong. Shoot, I'm lucky to be alive.

RSR

I can't speak from personal experience. Use google search "site:yotatech.com throttle body port 3vz 3vze" and see what comes up.

I have seen folks on here do the throttle body port to the 3vze and report that it improved performance. Folks that tried throttle body spacers reported that those did not improve performance.

I have these threads bookmarked -- probably in one of them. Like you I purchased my truck a little over a year ago, stalked these boards and others, and am slowly building out... Decided to make my "home" at yotatech however.
https://www.yotatech.com/forums/f116...-thread-77833/
https://www.yotatech.com/forums/f116...s-help-254690/
https://www.yotatech.com/forums/f116...nation-187078/
https://www.yotatech.com/forums/f116...k-3vze-187741/

RSR

Actually, here is the throttle body article I remembered:
http://www.off-road.com/trucks-4x4/r...ody-23080.html

jclofty47

Just like someone else asked, on the last link you put up there, wouldn't it be smart to have the intake match? Cause if the TB is 3mm overbore and nothing is done to the intake plenum wouldn't it be pointless? It'd be just as restricted as when you started. Some post somewhere said that the flow of your exhaust will always be restricted by it's smallest part, eg: 2.25" piping with 2 in flow on cat and 2.25" the rest of the way through, you're still restricted by the cat cause it's the smallest part in the exhaust system, causing a bottleneck. Wouldn't that be true of the intake as well?

RSR

Not necessarily. A larger throttle body would mean a larger throttle plate which means more air would get into our engine than the ECM thinks is in there, good on our rich engines.

The ECM would obviously correct to a degree due to the 02 sensor, but I would think just like the ISR mod, it would lead to greater throttle response and a smoother power curve. And you're going back to where I recommended you focus efforts elsewhere where you'll get more bang for the buck, time and effort...



Sort of like with the AFM mod too. When you increase the size of metering plates, more air can get in.

I would think based on the physics of air again, that the greater volume of air stacked behind a give restriction, the more pressure would build, creating add'l velocity of air at the restriction, pushing it through faster. So a larger AFM, a larger air intake tube, a larger throttle body, and possibly a larger intake plenum would presumably move air past restrictions you can't control for more easily. I might be off base here, but that's what I'm thinking.

The plenum is crap, and eventually somewhere in the main plenum intake tube, you'll have to stop the boring...

jclofty47

OK, so if the plenum was bored out, leaving the runners alone, wouldn't that produce the desired effect? Or maybe don't port it all the way through, but port match the opening to the oversized TB, creating somewhat of an air funnel? It'd be fair to say that it could be done with a dremmel instead of having it CNCed. That might just be worth it... the wheels are spinning...

RSR

Well I think it's really diminishing returns. The throttle gate is a restriction point regardless (at all times, but greatest benefit of larger is probably at full throttle). I think that's the benefit of the throttle body bore -- it makes that point less restrictive. If you bore out the plenum (I've never tried to take mine apart -- not sure what you're getting into w/ EGR and cold start injector at the end of that runner if boring, but you'll probably want to take all of that crap off before the metal starts flying), I think you're basically just moving the restriction point 6-8 inches further back.

As discussed in regards to the physical principles of air, I'm sure it'd help, but you're adding 6 inches (probably don't want to bore all the way to the back of the plenum unless you want to try to re-engineer the air tumbling principles of the plenum to ensure each intake gets approximately the same amount of air) of add'l volume/force pressure to the ~2.5ft of improved intake setup you've already created. So a ~20% increase over the work you've already done with a relatively quick and easy ISR pipe swap (boring part of the plenum is a 20% increase from whatever benefit you're getting from a bigger diameter intake pipe size preceding the restriction point at the near back of plenum). But I'd think the bigger flapper on a camry or supra afm would make a bigger difference than all the of the rest boring and piping combined (including TB), so long as you're properly adjusting it's lean/rich ratio with a wideband 02 sensor... As that's the biggest restriction point on stock setup. Next is probably the exhaust. Following that is the small valves (need larger which means pulling and machining the heads, new valves, etc) and performance cams or cam regrind to support new, better flow patterns of improved heads -- and if you're doing this you might as well pull the block and have it machined and rebuild your lower end to ensure you're not losing any compression, negatively affecting the performance you expect to be getting from your top end. And last would be the intake, including (in order of ease/cost) the ISR delete, the throttle body, and plenum. Or at least that's my opinion -- could very well be wrong, but this is my current understanding... Not that doing some of this stuff out of this order wouldn't benefit, it's just that you'll always be limited by the most restrictive/weakest point in the system -- wherever it may be found.

Personally -- and it goes back to my original post -- I'd leave the throttle body and plenum alone until you do all the other stuff that will be/has been found to be by others as a bigger bang for the buck/time/effort... On principle, all this plenum stuff should help, but it's playing in the margins unless you want to build a brand new plenum to put on your rig because our air intake is really that bad. And for you to benefit from a better plenum, you really need to fix all the other air intake and exhaust issues first... The approach should take into account the larger system too, not just the principles of that it should work/help to move you towards your goals b/c unfortunately pursuing theories on principles/physics/etc alone don't always work very well due to other weaknesses within the greater system...

And it also goes to whether investing the $2k+ in parts/specialized labor like machine shops alone is worth it to fix this engine when even with all of these improvements, it'll still be limited by its relatively small displacement for a V6. That's largely what leads folks to the 3.4 swap. You can basically buy a rebuilt 3.4 with all this stuff pretty much fixed and larger displacement for the same price or less to optimize the 3vze -- better designed engine, more power, and better MPGs. Really this is the first question you need to ask before you start modding -- what's the end goal?

I plan to do the 3.4 swap eventually, so the mods I am doing (like a 2.5" exhaust) I'm trying to make sure will work across both platforms, or is of such minor cost (like the AFM swap or ISR delete or running cleaner through the plenum) that I can justify it while still saving $ towards my ultimate goal of a swap...

jclofty47

Sounds like you really know what you're talking about. Believe me, I'd love to do the cams and valves and pistons and stroker kit, but that's all extensive engine work that I've never done before. I guess I was looking for something a bit simpler like the bigger afm and tb. Those will be 2 things that I do. I'll do them one at a time to see how much of a difference each one makes. I may go to a wider intake tube when I do this, and route my system for cold air. I don't have the time, the place, or the money to start on big engine projects at this point. Maybe by the time I'm ready for that, I'll be ready for an engine swap. Thanks for your help to point me in the right direction. I'm on the road and I get excited easily, so boredom and downtime are my enemies when it comes to my imagination/dreams of what I want the truck to be.

RSR

You're welcome -- don't thank me. Thank the Yotatech forefathers... Mostly just regurgitating what others have found.

And actually on that list of restrictions thinking further and not obsessing over the intake, a performance, high flow, mandrel bent exhaust should actually come before the AFM. I think the 2.5" is ideal -- others say the 2.25 (I think the 2.25s are actually optimized for the 22re not our engines like a lot of aftermarket stuff...).

The exhaust on our trucks isn't sufficient for stock intake/needed engine breathing, let alone after adding a supra AFM.

jclofty47

I had the exhaust replaced about a year ago. Don't remember what diameter pipe. I put the performance intake on before I did the exhaust and the intake was making the cat work overtime. Slight sulphur smell. But when I replaced the exhaust with all new mandrel tubing and hi-flow cat and muffler, that smell went away and from what I remember, it was more of a fuel smell. I wanna do the crossover delete on the exhaust manifold to free up some more breathing and remove the heat issue from the crossover. I don't need headers, not for $600 bucks.

Joseph101

how much of a gain would that give you