High Compression KA Question

[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!!!!!!

[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

[iveexcaped3]

what the issue is your on zilvia about built ka's..... this would be your best bet (http://www.ka-t.org/forums/viewtopic.php?t=58379&highlight=high+compression)

[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

[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

[diacris]

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

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

[mantas]

what the issue is your on zilvia about built ka's..... this would be your best bet (http://www.ka-t.org/forums/viewtopic.php?t=58379&highlight=high+compression)

My thoughts exactly....

[iveexcaped3]

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

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]

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

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.

[4x4le]

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.

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]

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.

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.

[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?

[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?

[diacris]

Ok I got all of the above problems sorted out. The car ran great for about 20 miles. Then all of a sudden, when I pushed the clutch in, the engine died. And when I try to crank it, it spins and spins as if the coil wire were unplugged.
Indicating little to no spark. I pulled a plug wire and let it ground to the body as the starter was spinning and the spark was almost not even there. When I pull the coil wire and let it ground, it has a good strong spark. I have replaced the rotor in the distributor, but not the cap. I'll be picking up a new cap later tonight. Even with the new rotor, still won't start. And I know it's not because I need "10mm wires bro", it ran with the 7mm's just fine.
FEEDBACK PLEASE. :hyper:

ALSO: It idles at 2000rpm, I have tightened the IACV screw as much as possible and it still wont go down. I have also vacuum gauge tested it. No vacuum leaks. And the ignition timing is retarded 15 degrees from stock. It's at 5 BTDC.

[iveexcaped3]

have you done a compression test on all your cylinders?

[diacris]

have you done a compression test on all your cylinders?

I'm about to go do that. If I can find my compression tester. I may have a leakdown tester instead.

The car died while I was driving, I pushed the clutch in and it died. When I pulled over and tried to crank it, it spun as if someone had just pulled out the plugwires; ie: no combustion. Since then, I've taken it home and tested the coil, wires, plugs, etc. Just tried to fire it up and it didn't start. I pulled out a plugwire and it would arc to any ground near it. But for some reason its not igniting the fuel during ignition? I'm not even getting a pop or puff, none of the cylinders are combusting. I picked up a new rotor and still no start. The plugs are wet with gas, so it's not that. I DID NOTICE that when I backed it out and started driving it this morning (when it died), it was very hesitant below 2800rpm. Then a little ways down the road I pushed the clutch to let it cruise to a stop and it died. It has also had a problem with idling way too high since the motor was rebuilt saturday. If I start it and let it idle, it will sit between 1100 and 1700. But if I apply the gas at all, it will spike up to 2000 and stay there then every now and then it will spike up to 2500, then go back down to 2000. Ive adjusted the idle air screw, but to no avail.

[diacris]

0 psi on all cylinders. Concluded that all 8 of the intake valves are stuck open due to a broken timing chain, or something else of the sort. :wtc::wtf:

[iveexcaped3]

if its 0psi on a compression test i doubt its ALL your intake valves. if you have the cylinder leak down tester do that. make sure your doing these test correctly or its gonna change all directions of what your looking at.

[rwtf]

maybe your rings failed? :S

[diacris]

I think its something to do with the intake cam. If I try to start the car and press the throttle at the same time, I can hear a "glug glug" from the intake tube. Makes me think that the valves are open and thats why there is zero compression and why you can hear the air being compressed through the intake

[pacotaco345]

Did you tighten your cam bolts down? I remember when I rebuilt my KA last winter and forgot to do that, dropped the #4 intake valves, stripped the hole in the cam gear, punched my headliner... Yeaaa never making that mistake again.

[iveexcaped3]

the thing is it wouldnt just be all intakes.... so you might want to retry that compression test..... if you read 0 again on all of them do a cylinder leak down test from there that will tell you exactly what got fu**ed up and where to start working

[GroundPerformance]

Sounds to me that timing components got loose or not installed properly. You could have bent the valves in the process which is why you have zero compression.

[GroundPerformance]

I've done High-Comp KA NA build and they're very nice and torque is crazy. In cali were SR cars are always on the lookout for cops. Having a OE setup with some power is not bad thing. The bad part is fuel.. If the best you can do is 91-93 its still doable with really realy good tuning but timing would really be on the conservative side. We use E85 and SR 370cc injectors on the motor with no issues and can add more timing with no knocking what so ever. MPG does suck and being constrained to E85 station is the main issue...

http://img600.imageshack.us/img600/5131/highcompka.jpg

[diacris]

UPDATE: The car has been running fine for a few weeks now, it ended up being that the dowel-pin wiggled out of the camshaft. Hitting 245 psi on cylinder pressure, runs fine on 93 pump gas. I've pulled up to 6k so far with no audible pinging whatsoever. Extremely hesitant until 3600, getting Knock Sensor code. I replaced my knock sensor with a 1 mega ohm resistor. Will be changing it to a 560k soon. Pulls absolutely great from 4k to infinity and beyond, but before 4k it's shit. Takes the bitch 5 minutes to warm up and run correctly. When I start it cold and press the gas it likes to stall out. Or it will just take 1 - 3 seconds to recognize that I've pressed the gas. Idles at 950. Took it out sliding earlier since it's been raining. Has a shit-ton of torque btw :cj:

[diacris]

UPDATE: The car ran good for about a month. Pretty sure I developed a vacuum leak somewhere, and it runs like shit. Got a tuned ecu from e-mance, also shit. Told me that it would run at 20 btdc, which is ludicrous given that i hit 250 on cylinder pressure. It pinged from idle all the way to 5k when I installed it. (I dont bring it over 5k, or I try not to). Tried backing it off to 15 btdc, still pings like mothafluther. Then, I tried 5 btdc. Hardly any power, but no detonation. So tomorrow (Sunday), I'll be plugging my stock ecu back in and I'll mess with the timing some more. Whenever I undo a certain vacuum hose going to an egr valve I get 14 psi vacuum, I hook it back it up and it drops to 5 psi. But anyway, having a very hard time locating the vacuum leak. To be completely honest I'm probably going to pull the motor and swap back in standard compression pistons. This high compression is a load of unnecessary bs. I've also had problems with my 248 intake cam jumping time a lot. I installed brand new timing kit, chain, guides, tensioner, etc, etc. Any ideas? Stock intake cam gives me 200 cylinder pressure, 248 gives me 250. If when I swap stock intake cam back in, and adjust the timing, if I don't get pinging. I'll keep the setup. But until then, it's just overwhelming and frustrating.
On a side note my friend bought a 240 today, he set the timing to 23 btdc and ran 93 octane. Couple hours later, ROD KNOCK. He was dogging the shit out of it. But is it possible that the advanced timing could have attributed to the knock? Or is it just that he revs the shit out of it and ended up oil starving the bearing? He has a stock rebuilt ka, .5mm overbore, cometic hg, stock everything else.
Any help would be appreciated, thanks.

[rcdad123]

wow, sorry about your bad experience. but if you decide to keep it with the hi comp and hi duration cams, get a tunable ecu that is tuned on the dyno in your car. there really is no substitute for a tunable ecu with an experienced tuner. i think with the right ecu and tune, you will have a very responsive engine.