Ka24e/z24i na build for the track. Suggestions/options wante

[Kronic_Chronicles]

I'm wanting some help and/or suggestions for bulding a naturally aspirated ka-e or z24i. Its for asphalt racing, 4 cyl class. Reason for not using the dual cam is because the max displacement for a 16 valve motor is 2236cc with stock valve size. I have two complete ka-de motors and one z24 block. I will have a single cam head shortly. The chassis will be a kouki z31, with a ka engine in it. Reasoning for the z31 is that it has been beat to hell, and I already have it in my possession. The car deserves more than being junked, and its not worth restoring and would too expensive to get it to pass inspection.

The class is mostly made up of foxbody mustangs. There is one Honda that is doing well, but the Saabs are dominating. I know that the ka-e has a stock hp of ~140. The mustangs have ~90hp. I strongly believe the ka or z motor will easily do better than the mustang 2.3, and hopefully the saab 99 also.

One main question I've had for a while, can anyone tell me if the intake manifold from a z24i will bolt onto a ka head? I can check this out at the junk yard if no one knows for sure. The class will allow fuel injection, but a majority of the cars are carb'd. Rules for fuel injection include stock intake manifold, a restrictor (size determined by officials), all air (including idle) must enter through restrictor, no funneling air.

I'm not planning on dumping $10k into this engine, so its not going all out. I have to stay under 2451cc. I have read that the max rev on a ka motor is ~7k. Our mustangs are built for 8k, but i don't believe the ka will need to be that high to compete. The block will work whichever way I go, ka or z24.

The main reason I am considering carb is because they will get suspicious if the car is dominating too much. The independent rear suspension may get me in trouble already, so I am wanting ideas to restrict myself and compare my car to my family's cars during practices before competing. I feel the fuel injected has more options to tune electronically and may be too effective. I have high hopes in Nissan and their technology, so its stuck in my head that it will beat ford, honda, and sabb lol. I could think too highly of Nissan, but I doubt it.

Gear rations is another thing I would like advise on. We are running on two 3/8 mile high bank tracks, with one of them being resurfaced this year. I have three FS5W71C transmissions, two from s13's, and one from a z31, along with two T5s from the z31 (yes i know the T5 wont bolt on, i would make an adapter). I would prefer to run my z32 lsd, but I may end up going with the z31 open diff or a j30 lsd. We have to run 13 inch rims with max width of 7 inches, so I cannot adjust gear ratio with tire/rim size. Our two cars are currently running in 4th gear, but are also using 4 speeds and a ford 9".

Suspension shouldnt be too much of an issue. With the z31, I have separate springs and shocks in the rear, and the mustang racing springs we have will work under the rear of the z31. The caster/camber adjustments may take some creative work to still abide by the rules, but I believe we can figure it out.

I am doing research, using google and the search button, so no flaming please =). I would like suggestions though, and am open minded so throw any crazy ideas out there lol. Thanks in advance for all ideas, opinions, and suggestions.

[seang]

I think that DE and z24 heads have similar combution chamber volumes (45 or so cc), but are shaped differently. An E head has somewhere around 64cc if I remember correctly. The tops of the DE pistons are shaped differently than the z24 or E pistons, not sure on the dish volume or how they might work with a differently shaped CC.

The exhaust sides on the z24 and E heads are very similar, I think the same bolt pattern, with port shapes a little different between the two.

Stock z24 compression is 8.3:1, E = either 8.6:1 or 9.1:1, and DE = 9.5:1

here are a few pics I had lying in my photobucket, thanks to whoever's they are, I just lifted them off different places on the internet.

KA-E intake side, this particular one appears to have been ported.


Thes two are naps-z heads. Top one is a z24, bottom one is a z20.

[Kronic_Chronicles]

the biggest issue is remaining under 2451cc. thats why i have to go with the single cam and cannot use dual cam. also cannot port the head or enlarge the valves sadly. unless i lower displacement to 2318cc or lower, then i can port it. so piston choice will definitely play a large role in this build. the class calls for flat top pistons unless using oem. im considering using vg33 pistons and boring 0.400 over, but i may have to use flat tops.

i feel im going to need to run high compression. mill the head, longer rods, pistons, thinner head gasket, and apr studs. they allow 100 octane racing fuel, so thats an option if i run into knock issues. exhaust will most likely be a custom homemade job, 4-2-1 header im thinking since im not doing high revs and wanting mid-high range torque. intake manifold im thinking with be a z modified mani, and probably mount a Holly carb on it like our mustangs. its supposed to be stock intake manifolds, but the saabs have custom intakes to convert from fuel injected to carb, so i should be able to get away with that.

[seang]

[Bigvinnie]

Stay away from the NAPSZ head. Its lack of valves is basically lack of power. You will want to go with 1989 sohc engine and mill the head down. You will want to roughly get a 9.5:1 compression or better so you might want to consider shaving/milling 2mm from the head or more if you are setting a preference for high octane. Or if not milling the head consider welding the quench area to lower cc and raise compression. The only advantage to lower compression is lower octane, however i wouldn't consider neither of the sohc heads for a racing format simply because the valve train is limited to about a 6800RPM redline, and this will also limit over sized racing cams without modify the valve train significantly. even with solid lifters for the KA-e you would only be getting another 500 additional revs.

You also have to consider squish and quench area's. If you weld the quench area to make it more pentroof like ( to raise compression) you will want a crater style dish piston. If You have a hemispherical style head and you just mill the head you will want a flat top piston design. This is how swirl and atomization occur in the cylinder chamber for maximum engine VE. If you use a flat top piston with a pentroof head more than likely the engine will lose engine VE.

If you absolutely had to chose between the 2 engines the ka24e would be the wiser choice of the 2 and there is still some aftermarket support available. With naps-z you would need fabricate alot of your own parts, and I've had experience with that head type and it isn't a good head for porting and is limited to an abundance of clearance restrictions.