diacris

I'm in the process of building a high-compression KA24DE.
KA24DE block bored .5mm over.
Dual 248 cams.
SOHC Flat-Top Pistons .5mm Over.
Decked Block.
Stock Head Components.
I calculated that the compression is going to be around 11.4:1. With this amount of compression, what should I be running for Ignition Timing? I'm under the impression that you Retard the timing when you raise compression / turbo / supercharge, etc. Stock timing is 20 BTDC. I figured I'd retard it to 16 BTDC to keep from detonating.
What are your thoughts on this? Has anyone had experience with this?

4x4le

You need to run proper base timing and tune the ecu. Any other suggestion is a hack up, wrong way of doing it.

cotbu

I agree!!!!!!

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diacris

Well, I plan on buying NisTune. But since it costs almost $500, I'm gonna have to wait until early January to have the cash. I'm just asking what ignition timing I should run until I get the ecu tuned. I just dont want it to detonate and ping. I'm aware that it wont make full power, I'm just looking for a safe amount of timing to run temporarily.

s13mikesr20

who ever is doing your tune should be educated to the point of where the timing should be let alone you better not be running low octane in the ka or you guys will never get the timing right cause it would be running like absolute dump and missing like a mother snuffer

but i have seen dyno techs not know a damn thing(besides how to strap it down and hit the gas)...

diacris

Well, the guy who is helping me build my engine keeps telling me that I need to advance my timing. But I know for a fact that when you raise compression you're supposed to retard the timing. But he's steadfast in thinking that it needs to be advanced and I dont want to fuck up my engine. And we will be running 93 in it.

4x4le

I would recommend as little basetiming as possible to get it to run then, but then again too little timing gets things a little hot too.

Your kinda in one of those pickles where no advice is good advice until tuned.
Advancing it is a no no, at least blindly. I know I have seen ka's with stock compression with correct basetiming knock on 87 and 93 is recommended in them anyways so even with 93 your going to be pusing it even with reducing base timing.

s13mikesr20

Yea 93 is fine but to get the most out of the high comp gotta run 100+ or e85 for that matter

Id say ask a race guru that has been down that route there's gotta be a thread in this forum of a high comp build somewhere and octane rating on e85 is up there but takes more e85 to run in the cylinder then regular fuel

If I was you I would get a second opinion a.s.a.p some people know how to build motors but when it comes to race timing when the cars running people can be dumb and fuck a 3k ka motor

diacris

Ive searched through a billion high comp ka threads but none of them are builds, they're all question threads. And if theyre builds they mention nothing about timing.

s13mikesr20

damn hmmmm gotta retard the timing not advance its not a rotary or a vtec motor
the thing will never run right talk him out of it....my.2

diacris

Gotha, thanks a lot for the help guys.

240sxr

the problem is that if you have a high compression KA with out a tune you need to retard timing a lot just to be safe,and will be slower than a stock KA,i've build one with the same set up you posted, p.m. me for more info

s13mikesr20

bam knew someone played around with it

diacris

Got the motor to start. Used the exact mods listed in the first post. The engine will run, but only if you hold the throttle open manually. It won't idle. When we pulled the sparkplugs, 3 were black, and the first cylinder's was white. The first cylinder also had the most compression when we compression tested it. 250 psi. the rest were around 240 and they fire just fine on 93 octane. the plugs are also gapped to 35. Is it blowing out the spark in the first cylinder? I need to get it running soon, but I dont have money for an ecu until late december.
The only things that have changed with my motor are sohc pistons, and dual 248 cams. What's causing it to run bad?

StryfeS13

Gap your plugs tighter maybe? Try 0.28" or something.

Possibly your cylinder 1 injector isn't flowing as well as the other 3. Either way your other 3 plugs are rich and first is lean.

Also you need a tune

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iveexcaped3

what the issue is your on zilvia about built ka's..... this would be your best bet

Kingtal0n

I am not against any experience of engine building...

However, this has got to be the most silly thing I have ever come across. The KA is not a HONDA engine. It should not be high compression and it should not spin 9000rpm. If anything, it should be turbo, 8:1 compression with a 6k redline. Anything more than that is asking for serious $$$ to be invested.

For under $2k these days you can strap a 250 horsepower redtop into a 240sx. Now tell me, why would you invest even 1 penny into a 130 horsepower KA engine? Even if you spray a 100 shot of nitrous it still doesn't make any sense, unless you are going to drive around without a hood (so everybody can see the OEM KA engine) and have the nitrous plumbing under the intake (so nobody can see it) THAT is surprise factor. not to mention high compression engines are hard on the starter.

And furthermore, I still feel (IMHO) that an OEM redtop, with OEM sidemount, and OEM exhaust, KEEP the hood on the car, and people think its an OEM KA engine... Yet the car has 200+ horsepower. That still beats a "sleeper high compression nitrous KA engine" fwiw

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5.3/4l80e/turbo 240sx playthrough:
https://tinyurl.com/turbo240

Kingtal0n

Oh oh, right, thread op Wants timing numbers.


Well heres what I feel. base timing at idle around 12-13*. Cruising on the highway around 36-37*. Under wide open throttle I would guess about 15-18* and go up from there. Peak WOT will be less than 30* I bet. most ancient chevy engines will tolerate 36* WOT total but that is serious VE deficit. Your KA will have decent VE thanks to it's valvetrain so I feel the final WOT timing will be much less than 30.

the way to know for sure is, of course, chassis dyno. Start LOW and work the timing up a few * at a time. When you see that no additional timing is necessary (no significant improvement) lock that spot down a few * retarded from where your peak, because there will always be a bad day, going uphill, with bad gas

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5.3/4l80e/turbo 240sx playthrough:
https://tinyurl.com/turbo240

diacris

LOL, because for $80 I can put high compression pistons in it and gain 20 hp.

mantas

My thoughts exactly....

iveexcaped3

because everyone and their mom slaps in a sr thats used and already beat up.... so why be like everyone else or for 2k you can have a fresh motor and a turbo kit if you know what your looking for and bust out more than 250hp...... also if the ka came turbo charged from the factory like the sr did it would be doing more than the 130 its at

iveexcaped3

oh and sorry to burst your bubble but the SR20DE N/A only puts out 140hp stock and 132tq where as the SOHC puts out 140hp BUT 152TQ.... DOHC 155HP and 160TQ

Kingtal0n

Nobody installs an SR20DE into a 240sx unless they just need a beater. Why take out a 2.4L and install a 2.0L? When did anybody suggest an SR20DE engine? ever?

#2
See those power numbers? they dont matter. Nothing under 200WHP matters, nor is anything under 200WHP considered performance. You cant trap 110mph with 130, 140, or 155 horsepower in a 3000lb vehicle.

#3
It costs more than $80 to install a set of pistons into an engine. In fact, just opening the engine up entails a long list of risks and possible problems forthcoming. $80 says a modified high compression KA goes fewer miles than a bone stock OEM redtop engine thats been used for 80k already.

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5.3/4l80e/turbo 240sx playthrough:
https://tinyurl.com/turbo240

4x4le

1. Ive seen some na sr's, they still actually make more power than a ka and can be had cheap.

2. Its a good way to sneak some power in for auto x or drifting on a budget. Everything isnt always about trap speeds.

3. Yea, it will cost more than $80 unless you already have some stuff laying around. But you have little to no faith in anyone building a nissan engine.

Kingtal0n

Oh, good, you hear that thread op? 4x4le has seen some na sr's, and they still actually make more power than a ka and can be had cheap. You are in luck, sir.

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5.3/4l80e/turbo 240sx playthrough:
https://tinyurl.com/turbo240

diacris

Got it running a few hours ago, drove it home from my buddy's shop and it felt very weak. So when I got home and pulled sparkplug wires 2 and 3, and it idled exactly the same. I has a smooth idle, but its not even running cylinders 2 and 3. They are sparking, but there is no combustion in those cylinders. any pointers? I'm about to go check the injectors, but tell me what you guys think.

rwtf

check injectors?

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diacris

Cylinder 3's sparkplug was "dark/maybe black". This is one of the cylinders that is not combusting.
Cylinder 4's sparkplug was "clean" and it is one of the operational and functioning cylinders.

diacris

Just cleaned off the dirty sparkplug from cyl 3 and put it in cyl 4.
Put the clean sparkplug from cyl 4 into cyl 3. Made no difference. So even with a clean sparkplug in cyl 3, it still doesnt achieve combustion.

diacris

Switched cyl 1 and 2 injector plug. 1 still functioned as normal. 2 was still non-operational. Hmm. Bad injectors I'm thinking?