Finished the adapter plate and match ported the MEVI throat to the TB last week, installed the TB last night.

Wow, what a difference! Maybe it's because I'm boosted, but I really wasn't expecting such a difference in throttle response. I was afraid it was going to be a bit soggy due to the lower air velocity through the throat, but it has turned out to be quite the opposite.

 

Very Nice! Got a write up or anything. I would like to try this sometime.

 

Slightly different view. Yes I know the cruise control cable is not connected. It was just a hair too short.

 

Dude your the king! This is exactly what I want to do. That's a 2000 Pathfinder TB right? I'm getting the MEVI soon so I need to know what I have to do and get. Should I use anyone special that can do the porting? Please let me know.

 

You definitely need to do a write up on this one...I am very interested in this one! Nice job!

-King Ryan-

 

Does that help boost kick in earlier than ~3000rpm?
At what rpm does yours kick in now?

 

It is more of a top end or low end thing.. makes me think with more air it would go top end, i have been thinking about doing this, without mevi.. hmm

 

Steve, you going to start producing the adapter plate for the rest of us?

 

I was going to make several when I made my adapter plate, but it was such a pain to make with regular tools that I only made one for me. I didn't feel as much of a difference with mine but I am N/A. I will track test it soon, and hopefully get on a dyno sometime.

 

That's what I'm thinking too. Either a top end thing, mid-range thing or low range thing.

 

How much larger is it? Stock Maxima is 62mm?? I know I've read it somewhere. ..not sure exactly though

 

Stock is 60mm, the pathfinder TB is 70mm.

 

Would this produce any gains with an auto and non-mevi, with HAI?

 

I was going to consider this mod, but I talked to KrisMax who was running the Pathfinder TB and he ended up blowing his motor (headgasket). According to what the mechanic said, it was severe detonation brought on by a very lean fuel mixture. KrisMax fears it was the Pathfinder TB that was responsible for this problem because he could never fine tune the TPS is accept the larger volume.

I'm not saying don't do this mod, but at least go to the dyno and make sure everything is looking good with the A/F ratios. Maybe the reason the SC Maximas have no problems with this TB is back because the FMU make a overly rich mixture under boost.


Dave

 

ran across this on ebay, would this benefit or is this only something that would work with pathfinder's, or is it another ebay bs mod? http://cgi.ebay.com/ebaymotors/ws/eB...tem=2437978585

not looking for flames, just figured i'd throw it out there in case it's something overlooked that could maybe help.

 

This is something that needs to be looked into for people wanting to do this on a NA engine. I noticed that if I set the TPS to give me correct voltage at idle, then the maximum voltage I could get with the Pathfinder TPS is 3.75V. The Maxima TPS gives 4V at WOT. If that is insufficient voltage to trigger WOT fuel mapping by the ecu, then you may indeed run lean at WOT.

 

Mardigrasmax was the first to do this. Give him the credit.

I used a 2002 Pathfinder TB. The Pathfinder TB from 2001 on is 70mm.

I ported the MEVI myself.

I spent about 30 minutes making a writeup of the procedure yesterday and then the forums crashed and I lost it. I'll try again today, only I'll make a copy first.

 

do you mean the tb didn't make a diff. or just the plate

 

If I can get a minimum order of 10,000 I'll buy a CNC mill and start cranking them out. Since that's not likely to happen, here are the dimensions I used. Note that the .25" diameter holes are eventually tapped for M8-1.25 bolts for bolting the TB to the adapter plate.

 

I noticed your plate is quite thick, do accept the throttle body does the plate have to be that thick?

 

The adapter plate has to be thick enough so that the bolts that are used to mount the plate to the intake manifold are completely recessed into the plate. If you look at slide2.jpg a couple of posts up, the recessed holes in the plate serve that purpose.

I could have saved about .188" or maybe even .25" if I had used a bolt with a lower profile head. The Pathfinder TB is shorter than the Maxima TB, so even with the adapter plate the edge of the Pathfinder TB is only about .25" farther away from the intake mounting surface than the Maxima TB. That was not enough to cause fitment problems with my intake pipe.

 

I don't think it helps boost kick in earlier. That's determined by the blower rpm and how the engine breathes. As a matter of fact, if you help the engine to breathe better you can actually see boost pressure drop, since you're removing resistance to flow into the engine. This is a good situation to have since for a given flow rate out of the SC compressor, a lower pressure can result in higher efficiency.

Right now with a 3" pulley I start to see boost pressure at 2500 rpm. At 3000 rpm I'm getting 1.5-2 psi.

I did this mainly to improve engine breathing at high rpm, now that I have a 7200 rpm rev limit. The low speed responsiveness feels good, although in stop and go traffic it's better to have a less sensitive response that the smaller throttle body gives you.

 

So what is the overall purpose for replacing the TB? Sorry for a dumb question. I have MEVI, soon to get JWT, 465cc injectors. Will having a maxima TB limit me on anything? Also did you get a z32 MAF too?

 

How did you port your MEVI? how much did you port for a good match?

 

The 60mm Maxima TB is the most constricting part of the intake path, until you get to the individual intake runners, so enlarging the TB lowers flow losses into the engine, especially at high rpm.

Yes, I'm using a Z32 maf.

 

I inserted a write-up of what it takes to do this in a new thread titled "Pathfinder throttle body install write-up", or something like that.