If you have a stock intake manifold, READ THIS:

[InsanityInc]

Here's the deal. I've gotten in touch with James from WasabiGarage.com, and he said that he HAD a KA24DE intake manifold in the works, but it was discontinued temporarily due to lack of demand, so I asked him if I managed to stir up enough demand if he would resume production on the manifold. The short answer is Yes, he will, and I need at least 15 buyers for him to do it. His message follows:

[quote=""James""]the only way for it to be somewhat affordable(rangeof $300-400ish) is not to have the coolant tracksgoing into the manifold. this would affect the idleat cold starts. For those that know how it is withoutthat it would be fine. But those that are expecting a$2000 intake manifold for a $300 price range is what idon't want. Because this brings my company name downwhen they put up a review expecting $2000 quality. Mysr20det intake plenum is bigger on the inside to holdmore air. If anyone is local they can check out theitem. this will basiclly be the same. and it is aquality piece.[/quote]Basically, it will be fairly inexpensive, but it will cause a bad idle when the car is cold, due to it being expensive to add the cooland tracts into the manifold. I don't really see this as much of an issue, seeing as how at least my 240 heats up quickly. He also said if people were opposed to this idea, he could probably make one with the coolant tracts, but it would definitely be more expensive.

Now, either post here, send me a PM or send me an email if you are interested in this. If you do not believe me when I say that a significant problem with the power production of the KA is the intake manifold, then read on for a thorough explanation of why it is, for either NA OR Turbo applications.

B18B stock Dyno:

Duration: 220/222 (advertised) 185/[email protected]: .395/.380

KA24DE stock Dyno:

Duration 240/248 (advertised) 210/[email protected]: .367

As you can see, the cam profile of the B18B is much more mellow than the cam profile of the KA24DE. however, the B18B makes peak torque at a higher RPM, and the torque drops off slowly. In the KA, the peak torque (maximum cylinder fill) is at 4000, and the torque drops off VERY sharply very soon after it peaks. This is also evidenced by cam changes having very, very little effect on the KA24DE. Theoretically, the KA24DE should have a higher top end due to the more radical cams, but why doesn't it?

The intake manifold.

As in the pictures, you can see that the B18B has much shorter runners than the KA24DE, probably by close to 8 inches or more. When you're talking about trying to achieve a maximum cylinder fill at 7000 RPM's, 8 inches DOES matter. Also, the stock intake manifold contains secondary butterfly valves which further restrict airflow. I have also included a mock-up graph of how a dyno for a stock 240sx with a different manifold would probably look. Note that this graph is only an estimation, and any attempt to hold James or myself to these exact numbers will cause me to find out where you live, hunt you down and shoot you for being a flaming idiot.

You can email me at: [email protected]

List of Interested People:

240SXforums.com:

SSDwellah(?)ch1873857wish ihada240slow4drUnoeganH.D.HUMPERDINK

NICO forums:

demcjklattr1Checkered-Member(?)BomexS13corn322(?)jmauld

and of course, me.

[InsanityInc]

And feel free to post any questions you may have in this thread, as well.

[TrunkMonkey]

i like the idea of a short runner manifold...

but there's no way you just compared the KA to a B18 in order to support your claims.

-demetrius

[Checkered-Member]

1. When you say KA? You mean a KA for the 240…not other KA motors…2. Coolant lines are there only when its hella bellow freezing to prevent icing on the throttle plate, no one needs the coolant lines.3. Will this be a short runner or long runner?4. How much are we talking about? Over 500?5. What about keeping our AVI and EGR? (I’ll get raped if I remove those (cali))

[InsanityInc]

Why? The torque peak of any engine is dependant on when the cylinder achieves maximum fill. They're both DOHC fixed cam motors, so the head is going to flow similarly. Thr torque peak, cam specs and runner length are all that you need to look at.

[InsanityInc]

1. When you say KA? You mean a KA for the 240…not other KA motors…2. Coolant lines are there only when its hella bellow freezing to prevent icing on the throttle plate, no one needs the coolant lines.3. Will this be a short runner or long runner?4. How much are we talking about? Over 500?5. What about keeping our AVI and EGR? (I’ll get raped if I remove those (cali))

1: Well, it'll be for the "KA", but it'll be designed to fit in a 240.

2: I'm just going by what james said on that plane.

3: short runners, james said they'll be about 5-7 inches long.

4: Without the coolant tracks, he said the price would probably be $300-$400 dollars, but that's tentative at this point.

5: Not sure what the AVI is, do you mean the IACV, or the PAIR valve? The IACV valve will be there, and the PAIR valve only connects up to your intake tube. As for the EGR, I asked him about that, and he said he'd do it if enough people wanted it with that. Both James and myself are in California, so we feel your pain.

[klattr1]

im very interested in an aftermarket intake manifold for the ka24de. If he doesnt build one then I'll just buy one of his universal 4 cyl. plenums, cut the stock manifold's runners and weld.here's a pic of my current dyno graph. i have Jim Wolf cams (256 duration) my tq doesnt fall off too much. so if i were to install a manifold like this, would it really be worth it or would it just kill by bottom end more than it already is?

[InsanityInc]

Installing a different intake manifold on a turbo car isn't going to hurt, since the only point of the longer runners is to make it so the incoming air builds velocity when the cylinders create suction (it's accelerating for a longer period of time).

However, with a turbo, you aren't relying on the suction of the cylinder to draw in air, so having longer runners just impedes breathing.

While the torque peak isn't a major selling point in your particular case (though it will help), the manifold will just flow better overall, and allow better cylinder fills across the board with a turbo, since the air has less distance it needs to move to get into the cylinder.

[Checkered-Member]

Both James and myself are in California, so we feel your pain.

where in cali...you said someone locally could stop by and check them out...

[InsanityInc]

Well, I'm not actually afilliated with James, I just wants me a shiny new intake manifold.

James' site is http://www.wasabigarage.com, I think it has his location there.

[InsanityInc]

I've got 3 people interested here (I think), and 2 on another forum, so only 9 more to go!

Tell your friends, family and pets about the manifold!

[klattr1]

here's some different pics of aftermarket intake manifolds that have been previously made for the ka24de:

[TrunkMonkey]

here's a more accurate test result of a short runner manifold.

-demetrius

[klattr1]

good look demcj.hmm, enthalpy did add 2 deg. timing as well but you can notice the visible difference in the graph up top.

[BomexS13]

Where exactly is the shop in Cali, I want to drop by and take a look:)

[InsanityInc]

Where exactly is the shop in Cali, I want to drop by and take a look:)

He actually didn't mention where. I emailed him asking, since someone else requested the same info. I should have an answer tomorrow.

[InsanityInc]

here's a more accurate test result of a short runner manifold.

-demetrius

Is that a KA or an SR that he's taking the dynos of?

[TrunkMonkey]

SR.

-demetrius

[InsanityInc]

who so far is willing to buy the manifold?

[BomexS13]

WHen I Have the money I'll buy one. As of now, I'm only intersted until i see the finished product.

THat picture posted above that was taken from onlineshowoff.com, gawd that engine bay is b-e-a-u-tifull:drool

[NateDogg]

Good idea. I support it but I won't buy one (supercharger project).

klattr: take a look at the dyno from Jay's SR. That is the type of change you could expect from this manifold. Less low-end torque and more top-end power.

[klattr1]

Good idea. I support it but I won't buy one (supercharger project).

klattr: take a look at the dyno from Jay's SR. That is the type of change you could expect from this manifold. Less low-end torque and more top-end power.

well, i know that and the same applies w/ aftermarket cams but thats not particulary true in his case. He makes more torque in the low end after putting that intake manifold on (compare 3.5k, 4k, 4.5k rpms). that is because that manifold flows better all around. Now, his peak tq is a hair less but there is more area underneath his torque curve in the second dyno.

[corn322]

hmm... how would short runners affect performance on a n/a ka24? Like, would the short runners kill low end performance.

I remember a while ago there was a post in here about runner length tuning, there was even a link to a website that talked about it.

[InsanityInc]

Not really. The longer runners and secondary butterflies are just designed to make low-end torque. Most cars have shorter runners, but this engine was designed with trucks in mind. Also, loss of torque on the low end isn't as noticable as lack of torque on the high end. You'll probably lose a bit off your peak, but the band will be MUCH wider, and generally better.

[InsanityInc]

James is located in pasadena, but he said he won't be open to the public until he moves to his new shop (soon).He also said he'll have a dyno in his new shop.

[corn322]

Not really. The longer runners and secondary butterflies are just designed to make low-end torque. Most cars have shorter runners, but this engine was designed with trucks in mind. Also, loss of torque on the low end isn't as noticable as lack of torque on the high end. You'll probably lose a bit off your peak, but the band will be MUCH wider, and generally better.

Yes, wider is better. So there's a chance I'll loose a bit of low, and a bit of peak, but I could generate 75% (or more) of max of it over a larger range.

I remember a while ago I measured the intake runner, or at least made an attempt to. came out to like 18 inches. when I put that info into the formula on aforementioned website, the numbers I got from it matched torque vs. rpm in real life.

another question I have, is James going to tune these, or experement on a dyno at all? or is he just going to throw this together?

and I found the website:http://rogueperformance.com/Up...tml#a

sorry if I'm coming off as intrusive or what not, I'm just really interested in this.

[InsanityInc]

He will test and tune them and make sure everything works right, it'll take a few months for the whole process to be complete.

[corn322]

another thought: I see how in the pictures of the short runner mani's on those ka's, it looks like the runners curve down a bit, my guess is so airflow through the head will be a bit smoother.i.e., if the runners hit the head at a 90 degree angle, when they got to the head they'd have to make a tight bend down to the valve area/combustion chamber. lets see if I can do some art...n/m I gotta go.

[NateDogg]

InsanityInc:

Your statements depend a lot on what James will do. Will he re-use the stock runners? What radius from plenum to throttle body, plenum to runner will he use? What is the total volume of the plenum and runners? Will the runners narrow or remain the same size? What shape are the runners? Even if we knew all this we couldn't foretell what the end result would be! Fluid dynamics is complicated business and that's why it takes a lot of money and effort to get it right.

The KA runners are actually tuned to have a maximum torque peak at 4000rpm on the second reversion wave. So when does the KA torque peak?? 4000rpm!!

What I suggest is that James may want to tune the runners to about 11.5" (runner length always includes area from valve to intake port which is 2.5") with 1.5" diameter runners. This will suggest a tq peak of 6000rpm on the 3rd reversion wave with stock ''91 cams (240 duration). This leaves some fudge space for larger cams (tune for higher rpm) without going too high above the KA's relatively low rev limits.

Just my $.25

P.S. I found the formula at grapeaperacing.com

PPS: Tuned length runners for 7000rpm on the 3rd reversion wave equates to 11". So the actual 'runner' should be 8.5". Any shorter and the 'tuning' goes out the window. Keep in mind this is only applicable for 1.5"D runners.

[InsanityInc]

No, he isn't going to use the stock runners, that would be more expensive than making his own. The runners will remain the same size (or possibly larger). The volume of the plenum will be larger than the stock one.

Yes, it's obvious they're tuned to make a peak there, but that's not a good thing for a sports car, that's why you need a different manifold.

11.5" is still very long. When you rely on multiple reversion waves to give you a specific peak power, power at other rpms suffer badly, because there's no guarantee that air won't be travelling away from the engine when the ports open, and that's never good. While the 11.5" runners might produce a torque spike at 6000, the curve would not be very good. The reason why such a long runner was used in the KA originally, is that suction from the cylinder accelerates air, it doesn't give it velocity instantly. So, if you're acclerating for a longer length, the air reaches a higher velocity before it hits the cylinder, allowing for a small supercharging effect, and more torque. Unfortunately, it also take more time to move the distance of the runner, so high-rpm operation suffers.

James does have experience making intake manifolds, so I trust that he knows what he's doing.