Like many of you, I am always on the quest for more power. Power is good. I spend countless hours studying the 5VZ, magazines, and books looking for ways to improve efficiency and free up some HP – always keeping cost as a consideration.

5VZ Throttle Body Bore

If you look at the 5VZ’s throttle body, you will notice a slight taper, a lip, and the butterfly valve.



A traditional TB bore enlarges the TB all the way through, and includes replacement of the butterfly valve to one of a larger size. These normally run at least $300 with a core exchange.

The 5VZ’s TB is a good design, but it can be improved. For example, Spoon Sports, who supplies high-end all motor parts and supplies to Honda enthusiasts, sells tapered throttle body upgrades. They improve upon an existing design without increasing the diameter at the butterfly valve. That is exactly what I did. By using a Dremel tool with various attachments, I removed a significant amount of material up to the butterfly valve. This avoids the necessary port-matching of the intake manifold on traditional TB mods.




I also removed 90% of the TB “lip” in the process. Part of the lip was left in front of the port that supplies incoming air to the TB coolant passage.




The finished TB is smooth, tapered, and contains virtually no lip.



“O” gasket Mod

This mod appears to only be applicable to early production 5VZ engines. The stock metal gasket is a “D” shape, restricting air-flow. Now would be a good time to replace the stock gasket with a more efficient “O” shaped gasket. I should have a large supply of these gaskets very soon, and I will sell them cheap. Late model and SC’d vehicles should have the “O” gaskets already.




PCV Breather Mod

I do not recommend the PCV mod. 11.20.04

Overall Performance Gains

Unfortunately, testing was hindered by 106 degree temperatures. Generally speaking, TB upgrades yield a 3 HP increase throughout the rev range. So, it would be next to impossible to “feel” the power increase. I can tell you right now that these mods will not turn your 4Runner into a screaming all-motor machine. However, every little bit helps. Plus, I can now say that I am one of the few 5VZ’s out there with a TB and PCV upgrade. Want to join me? If enough of you show interest in these mods, I will submit a full write-up to Corey. Please let me know.

I would not recommend the TB bore to the Supercharged guys. As we all know, the superchargers flow more than enough air as it is, and this mod would only amplify the fuel starvation problems.

I look forward to your thoughts and feelings about these mods.

 

Wow, even though i don't have time to read it cuz I'm supposed to be working......I skimmed over it and I am amazed. You really got some special knowledge up there christian. Just too bad you don't work for Toyota like someone else.......

 

Looks good Christian. I'm wondering about the TB mod... you mention its smooth. How smooth is smooth? Those dremel bits seem rough to me. Did you need to go back with a finer grit wheel to polish it?

I'd definitely be interested in seeing a write up.


One last thing....how do we KNOW its a type R breather? I don't see any blazing red R on the top.....

 

Thanks for the compliments guys.

Tom-

For the initial milling, I used a 120 bit. Then I used a wire polishing brush, sanded it by hand with fine grit paper, and followed that by a polishing pad with compound. A thorough cleaning was also necessary.

It's just as smooth as when I started. The last pic looks like it might be rough, but its just the flash. Smooth is good in front of the butterfly valve, but the intake manifold is rough - which is good. Believe it or not, turbulent intake air is a necessary thing.

 

Ahh, OK cool. I knew there had to be more to it! Again, - great work!

 

Looks like a good idea Christian. So what's next, port and polish??

 

Nice job, Chirstian.



G

 

This is what you plug if you do the breather mod.

 

Good Stuff!

Put me on the list for on eof those "O" gaskets, please...

 

Jayson- The 98's should have the newer design. Of course if you find out otherwise I would be happy to get one for you. I am trying to get 20 of them.

 

O.k. Christian. I'll try and double check that. Thanks!

 

Christian,

Great work as always. I'm going to clean out my TB and if mine looks like yours, I may end up doing the same. Do give us a progress report after a month though. If all is well, most likely I"ll do the same.

Bob

 

Me too!
Save me an O gasket!!!

Christian, I have to say that I'm very impressed. I knew that you know your stuff (yeah, I know I hate that beginning too) - but I didn't know that you KNOW your stuff

Looking forward to hearing those testing results. Hopefully the heat and the gas prices both go down soon!

 

Great writeups! Please put me down for an O-ring gasket, mine is a 'D' style.

 

Just to let ya know, the late model 3rd gen.'s do not come with a "O" TB gasket from Toyota. Mine is a 2001 and I just put in the S/C and didn't have the new TRD "O" gasket, so the "D" one is in there now until the other one gets here Wednesday. I'm assuming the 2002 also comes from Toyota with the "D" TB gasket, but I can't say for sure. 2001's definately come with the "D" one though.

Zach

 

I recall from somewhere many years ago that the vacuum aids scavenging the blowby from the crankcase? And that under high throttle the valve is actually closed anyway.

 

Ok.

Are you asking or telling?

 

hey christian, looks great. the only problem is no one will believe you have vtec and type r on your 5vz, you might have to go with the billet oil cap so people know youre not messing around

 

Actually, I was thinking about slapping a "VVT-i" sticker on there.

 

Just curious if you've heard of it.