TB from a KA24DE

[crazyhayseed]

I started poking around my junk 240 motor today and realized that it's TB is about 5mm bigger than the VG30's. So I swapped them.

 

It took a little modification. I literally had to install it upside down, so it opens in the opposite direction. I had to reroute the cooling lines and get creative with the throttle cable.

 

The TPS looks like it's the same. It has the same serial number stamped on it as the VG's.

 

The throttle response is better, but I've still got to iron out the idle. It's running at about 15-20k at the moment.

 

This will either end in disaster, or help me to suck down even more gas in traffic... Here's some quick pics:

 

 

 

I'll take some comparison shots in the morning.

Edited February 3, 2008 by crazyhayseed

[GhostPath]

That's a common mod for the Z31 guys - Pathfinder manifold, S13/14 throttle body.

 

You need to port the manifold a little bit around the TB flange to get it to work properly.

 

Also, if you wish more power (but don't care about fuel economy) bypass the cooling lines on the throttle body so coolant does not flow through it.

Edited February 4, 2008 by GhostPath

[crazyhayseed]

That's a common mod for the Z31 guys - Pathfinder manifold, S13/14 throttle body.

 

You need to port the manifold a little bit around the TB flange to get it to work properly.

 

Also, if you wish more power (but don't care about fuel economy) bypass the cooling lines on the throttle body so coolant does not flow through it.

 

Really? That little bit of coolant will add power? How so?

 

Ya, a little shave on the bottom of the intake would help. Again, I'll take pics.

 

 

I'd really like to see how the Fairlady guys do it, because this took quite a bit of grassroots engineering to fit and my idle is still off. If there's a right way, I doubt I accomplished it.

[GhostPath]

Really? That little bit of coolant will add power? How so?

 

Ya, a little shave on the bottom of the intake would help. Again, I'll take pics.

I'd really like to see how the Fairlady guys do it, because this took quite a bit of grassroots engineering to fit and my idle is still off. If there's a right way, I doubt I accomplished it.

 

Ask them for yourself: http://www.z31.com

 

 

It adds power by not heating the air flowing through the TB. Cooler air = denser = more power.

[crazyhayseed]

Ask them for yourself: http://www.z31.com

It adds power by not heating the air flowing through the TB. Cooler air = denser = more power.

 

NM. After reading several of the threads over there, I think I'd be better off figuring it out for myself.

Edited February 4, 2008 by crazyhayseed

[crazyhayseed]

Ok, here's a comparison.

 

240sx modified Vs. Pathfinder

 

Stock

 

KA24DE

 

The '91 KA24DE throttle body is 6mm bigger than the '95 Pathy VG30's at 60mm versus 54mm.

 

The stock PF throttle position sensor would not work. The ECU won't recognize it at all. So I retained the 240's TPS and just retarded the timing a bit to bring the idle RPM back to around 10-12k.

 

GhostPath, I took your advice and bypassed the TB coolant lines. I believe the intake cooling would be further helped by a phenolic spacer on the lower manifold.

However, I noticed a couple more water lines running through the upper manifold???

 

I'll try to get a shot of where the manifold needs to be trimmed once I get the TB cleaned up.

[GrimGreg]

Can't you swap the throttle connections and springs from one to the other?

[Casey.T]

Can't you swap the throttle connections and springs from one to the other?

 

Im pretty sure you can.... Now your going to make me go look at the 2, 60mm tb i have from a Max VG30DE....

 

They are for my 300zx VG30DE

[crazyhayseed]

Can't you swap the throttle connections and springs from one to the other?

 

I'm not sure. The way this one set up, I had to flip the TB over. So the throttle cable is pulling from the other direction now (under instead of over).

Since I wasn't sure if it would work or not, I was afraid to disassemble the old TB. It'll be worth taking a look at later.

 

I think, if you take apart the 60mm TB, you'd be able to rebuild it to correctly fit the Pathfinder.

 

For now, it's idling well. It starts up at 10k, then settles to around 6500. The peddle is smooth but quick.

I'm throwing a CEL though. I'm pretty sure it's the 240 TPS, but I'm not going to fool with it so long as it's running well. I'm afraid I'd have to reflash the CPU for the new sensor, which I have neither the time or money for ATM.

 

Here's an inside look. The "orange" ring is the intake manifold peaking. That's what'll need to be ported.

[Casey.T]

Your showing me all the things I get to look forward to once the garage warms up a little.... no fun working in 33deg F....

[bigdave]

Any gains are going to be heresay. The stock throttle body will flow good enough to support more than twice what the motor is putting out in stock form. You will never notice the difference unless you compliment that mod with some headwork, fuel delivery, and exhaust. You probably still wont notice much from the vg30 unless you have a turbo or s/c vg30. Take my reply and use it, ive done several 60mm throttle body swaps on the older z's with L28 motors. Its always the same old stuff, grinding the manifold, and my friends always complaining that theres no difference. The only thing thats gonna happen is that air velocity is going to be reduced installing a bigger throttle body on an engine that doesnt need it. I think Nissan did a good job matching engine components to flow evenly.

 

in short (cliff's notes), dont bother.

[crazyhayseed]

I didn't go at this with huge power gains in mind. I had the parts and time on hand, so I used them.

 

Hearsay all you want, I'm just saying my pedal feels better and I got to play with my truck this week-end at absolutely no cost

[solid snake]

call me dense, but wouldnt it be easier to port out the pathy TB to 6mm and then install the KA24DE butterfly?

[VegasPathfinder]

The '91 KA24DE throttle body is 6mm bigger than the '95 Pathy VG30's at 60mm versus 54mm.

 

The stock PF throttle position sensor would not work. The ECU won't recognize it at all. So I retained the 240's TPS and just retarded the timing a bit to bring the idle RPM back to around 10-12k.

 

Couple questions.

 

Why would you think a larger throttle body would do anything without making the MAF larger as well?

 

Why would you retard the timing? You are losing power by retarding the timing!

 

I bet if you put your Pathfinder on a dyno before you did these mods you would have had more power then than now. A larger TB with the same size MAF with retarded timing will make less power IMO.

 

Mark

[VegasPathfinder]

I didn't go at this with huge power gains in mind. I had the parts and time on hand, so I used them.

 

Hearsay all you want, I'm just saying my pedal feels better and I got to play with my truck this week-end at absolutely no cost

 

 

Placebo maybe?

[crazyhayseed]

Placebo maybe?

 

No, not at all. The KA TB definitely had a smoother action. The original was sticking closed (even after I'd cleaned it). The different set-up helped that.

Pedal response shortened too. It didn't take near as much effort. Just a little pressure and you're rolling.

 

I won't argue power gains. If I'd been looking for a lot more power I wouldn't have used the stock intake hose and filter, would I?

Fact is, without a whole host of other mods, this probably wouldn't do any good anyhow. Intake mods rarely do... save forced induction.

Please, save the "dyno" card for the newbs. You know better than to think a pissy little swap like this is worth it.

It doesn't seem like this motor is as responsive to upgrades as the others I've worked on anyway. The GA16 has more potential than this... With a lower price tag I might add.

But it doesn't hurt to try and if I document it here it will save someone the trouble latter.

 

Anyhow, I had to change the timing due to a fault between the CPU and 240 TPS. They didn't like each other and it sent my idle through the roof. All other adjustments wouldn't put it within range.

This eventually (three days later) led to issues with the tranny, so I had to go back to stock set-up.

 

As far as the MAF, it doesn't look like the KA is any bigger. The piping is all the same size too. I don't think it'll be a bottleneck, but I can break out the caliper to be sure.

Though, with a CPU upgrade, you could use any MAF you want. One could easily swap to the Cobra set-up that the turbo guys use, but I'm trying to avoid anything fancy.

 

At this point, I feel I've done what I set out to do (albeit a spontaneous act of tinkering). I know that it will work, it just won't be a direct replacement.

I'll work on it more when the weather warms up. ATM it's too cold to think.

 

 

And NO, unless you are (or have on hand) a machinist, it's not easier to bore the stock TB. I don't know if it would be able to loose that much material. Even so you'd have to notch or swap the rod to fit the new butterfly. But it would be great to see that done. I wouldn't mind at all if I'm wrong there.

 

You may talk to the guys at rabidchimp.com. They bored the TB on my brother's MK2 Supra. Maybe they'd take a look at this one.

[purdyboy89]

HEHE im a machinist. but atm i dont have a spare TB that i could rip apart and bore out.

but what r all the advantages of doing such other than more air/gas?

[VegasPathfinder]

HEHE im a machinist. but atm i dont have a spare TB that i could rip apart and bore out.

but what r all the advantages of doing such other than more air/gas?

 

In my opinion there would not be any advantage without removing the restrictions starting with the airbox through the MAF then to the TB. A 3.0 making 150hp will see almost 0 gains from a larger TB.

 

I assume crazyhayseed was looking for an improvement in performance otherwise he would have replaced his ill-running TB with another Pathfinder unit. In this case he saw issues with the factory software and tried bandaid attempts to make it work and threw in the towel.

 

Here is a pic of a intake mod that works well:

 

 

Other than that, save the hassle.

 

 

 

Mark

[crazyhayseed]

I assume crazyhayseed was looking for an improvement in performance otherwise he would have replaced his ill-running TB with another Pathfinder unit. In this case he saw issues with the factory software and tried bandaid attempts to make it work and threw in the towel.

It doesn't sound very nice when you put it like that. I prefer "hiatus".

 

The experiment came from trying to fix a sticky TB. That's it. Nothing more.

 

The "Band-Aid attempts" were made to avoid tearing apart the original throttle body in case I ran into issues and had to swap back in a hurry (the truck is still a DD and we're in the middle of some darn cold weather).

All of which turned out to be good judgment on my part if I do say so.

 

 

The point of a larger TB on ANY application is better throttle response. However, as Vegas points out, it’s a moot point without streamlining the flow of your entire intake system. Were it a sports car, you'd be looking into a CAI, higher flowing filter and possibly larger MAF.

With this engine, you'd also need to port you plenum for the new throttle ID. Looking into lower manifold and head intake ports probably wouldn't hurt either.

 

Of course, most of this is worthless if you're not going to open up you exhaust as well.

 

Again, intake upgrades don’t make big performance numbers. They merely enhance the total package.

 

I'd also like to point out that, even if you're going to spend the money involved in forced induction, the above still applies… with even greater emphasis actually.