throttle body upgrade?

[S13 240SX]

I am trying to find out if I can upgrade the sohc ka throttle body for a little bit more power. Can i? and which throttle body to use? What gains would I notice?

[Bigvinnie]

I am trying to find out if I can upgrade the sohc ka throttle body for a little bit more power. Can i? and which throttle body to use? What gains would I notice?

You can upgrade the TB with a port and bore, then a new butterfly would be installed.I can't give you the exact gains it makes on the KA, but I do know that VG30e guys use the KA TB on the VG30e engine. Stock diameter of the VG30e TB is 56mm, the KA TB bumps the it up to 4mm for a total of 60mm. It was noted that the increase in diameter size was a 4% increase in torque and HP through out the entire power band.I guess the power difference would be the same for the KA as the VG 30, I don't exactly know the math involved in calculating the difference in HP to the diameter size of the TB.http://www.maxbore.com can upgrade your TB for $100.

[S13 240SX]

oh **** that 100 dollars and only a 4% gain. waste of money.. how about the ka24de is that bigger throttle body than the sohc ka and will it bolt up to the sohc?

[Bigvinnie]

oh **** that 100 dollars and only a 4% gain. waste of money..

Well the KA TB's are the same size SOHC or DOHC. You didn't pay attention to what I told you either. It is a 4% gain on the VG30e at a 4mm increase in diameter size. When you get it bored and ported you can get up to a 5~10mm increase, depending on what kind of power you want from your engine. That is a deal....If you want to buy an accufab or BBK and then take the time to modify it it will cost you $250~$300. Believe me throttle body boring is a good deal.

[S13 240SX]

ughhh well then maybe i'll just e-mail the place and see what they can do for it.

[TrueSlide]

4% is roughly about 6hp, thats a six HP throughout the whole powerband for 100 bucks not bad. Thats better then a 200 intake thats yields about 5 in a small part of your powerband.

[eddiec]

vg30 peeps upgrade because of their larger displacement needing to breathe more. and yes the ka throttle body is bigger than the vg30 and will flow more for that motor.

the ka, which has less displacement with the bigger throttle is already near is max efficiency as far as throttle size is concerned.

i'm not sating it will not work, it will. however the gains might not be all that their hyped to be. if anyone can produce dyno charts of a before and after throttle swap with noticeable gains then color me wrong and ill informed. but for now i'll hold to my opinion that its not worth the trouble.

[RACE 66]

Guys take a look at: http://www.ka24de.com They are advertising a Ford cobra TB to be used on the "DE" series engine. But they do say, you will need to re program your ecu. Food for thought.

Modified by RACE 66 at 9:55 AM 12/21/2005
Modified by RACE 66 at 9:56 AM 12/21/2005

[All_Motor_KA]

KA breathes fine, even in stock form in get's more then enough air to the manifold. I don't think a bigger throttle body would do much, maybe for a turbo car. But, an all motor KA would not benefit much from a bigger throttle body. I mean, everyone uses the KA throttle body to upgrade. S12 guys, those for the VG's and even my friend with a tercel turbo wants my old throttle body from my single cam. Just my 2 cents. Let us know how it works out. I would really like to know.

[Bigvinnie]

The KA breaths fine, but the KA already has a signicantly rich ecu tune. Every time your butterfly opens in the lower RPM the KA is dumping more fuel than needed, probably to help with lowering the NOX with richness of the fuel. (Fuel as a liquid is harder to burn than air, actually lowering emissions, obviously bad for performance)So now lets say you install a larger TB, and the TPS is positioned the same that the smaller TB was. You just increase throttle correction and have allowed more air to enter the engine, than having the smaller TB. More air is now used with the fuel leaning out the engine more. This will overall increase acceleration, torque and HP.

EDIT:Just did a bit of investigating on TB diameters, and it seems that Honda knows what there doing.Acura RSX Type-s K20a/TSX K24a use a 62mm TB for a 2.0~2.4litre displacement engine.Integra R type B18 uses a 62mm TB.The upgrade for prelude H22 is 62~65mm.

^^^^^All of these engines show greater improvement than the KA with lower displacement.^^^^^^^^

L28 MPI guy's are also utilizing the KA TB, and have noted that a larger TB than the KA TB could be used.........

The stock diameter size of the TB for the KA is fine if your into passing smog, for swirl and atomization, as far as increasing performance don't think highly of it.SR20 also uses a 60mm TB and is 2.0 litres.......

If you ask me something just isn't adding up.....


Modified by Bigvinnie at 12:45 PM 12/18/2005

[SimpleEnigma]

Somewhere i read that the 70mm TB from old 5.0L Mustangs would bolt up and work fine so long as you used the Nissan TPS.

Also, Tomei makes a 70mm TB for the SR that will mount up also.TB upsizing is a great idea. think about it for a sec, especially if you have an aftermarket intake system. Your intake tubing diameter is around 2.5" to 3" in diameter. It only makes sense to me that you would want to increase the size of your throttle body to match the size of your intake pipe in order to decrease intake restriction.

Would you go with a high flow cat-back exhaust system and not upgrade your cat?

Without an intake system to match the TB, i dont think a great deal of improvement would be seen, but added in conjunction with other performance parts, the improvement really becomes apparent.

look at the V8 guys for example, one of the first things they do in conjunction with a new intake system is upgrade from 70mm to 80mm TB's.

[Bigvinnie]

Somewhere i read that the 70mm TB from old 5.0L Mustangs would bolt up and work fine so long as you used the Nissan TPS.

You read correct. After market 5.0 mustang TB's fit. But you will need a spacer, or a slight port and bore of the manifold in order for the butterfly to open without any problems. Profesional product's, BBK, and accufab make TB for the 1986-1992 5.0 litre mustang/mercury cougar.The only problem is that you don't want a TB to big or it will decrease swirl and atomization. I believe 70mm is as large as it would want to get.

[Dattebayo]

The throttlebody from a JDM N15 Pulsar Kit is on sale from spl parts. It says it wil bolt onto a S13 SR20, and the KA24DE has the same bolt pattern. Its much more bigger and expensive though.

I personally am upgrading my mid-50's mm CA18 throttlebody with a KA-e TB and should see about 5%. You will have to use a dremel to make the hole sizes match up, I assure you no matter what the motor.