High Compression Ping

[JJ240]

Im rebuilding the bottom end of my KADE currently. I was going to wait till this summer to do cams/header/exhaust and 8.6:1 KAE pistons for 11.1:1. But I dont want to pull the engine again this summer. So I may do the pistons now. My one question is how the heck will 11.1:1 not ping on 93 octane pump gas. The only reason I considered that high is because Ive read other posts that say it works. My father who will be helping me with all of this said he would be worried about detonation with anything over 10 on pump gas. Hes a bit conservative about things like that though. Anyone able to give me some advice or explain what steps have to be taken to prevent pinging?

[Movingviolation240]

the new 3sGTE is running like 12.1-1 it all comes back to head design. With a KA I think it's right on the edge of safe with 93 octan, you could always use the '90 pistons that have slightly lower compression (.5 lower).

I think you'll be allright though, as long as you don't run a lot of timing.

also check out http://www.pinnaclenissan.com for some great prices on pistons.

Paul

[JJ240]

Ok, Thanks. Anyone have 11.1:1 without any mods to their fuel system or other internals? if so, how is it working for you?

[JJ240]

OK...desicion making time is coming. Engine is on the stand with the oil pan off waiting for a bigger socket to remove the underdrive pulley to get the crank out. I have to decide what I want to do with the piston situation soon. Im still speculative about 11.1:1 compression. If you have any thoughts about it please post I just want lots of input to sort.

[TrunkMonkey]

what's the highest octane gas in your area?

-demetrius

[piratepete]

Do it and let the rest of us know how it turns out.

[sultan]

you could do what this guy is talking about for more octane: http://www.zcar.com/forums/rea...41707 also read the post by pallnet, he has a high compression straight six.

[JJ240]

FINALLY...ive been trying to post for about an hour now. i guess my browser was messed up because it would keep redirecting me to the login page after telling me i was logged in. but anyway I can get 93 octane for sure, maybe 94 if I look around. And no im not too keen on being the guinea pig since im in college and my income is really low i cant afford to change anything if it doesnt work as planned. as far as mixing fuel ive read alot of good posts on these forums too about mixing, but it doesnt sound very nice to have to mix fuel just to drive to work and school.

[I am Technoman]

I would not recomend 11.1 for everyday driving. 10.5 would be alot better. Have your pistons milled.

[JJ240]

I considered that. I have access to a mill and a lathe, anyone have a clue on how many thousands of an inch removed would equate to .1:1?

[themadscientist]

does anyone make metal head gaskets for the KA? You can squeeze a little more or less compression by adjusting gasket thickness but I am unaware of the aftermarket support for this engine stateside.

[lessthanjakejohn]

Quote »does anyone make metal head gaskets for the KA? You can squeeze a little more or less compression by adjusting gasket thickness but I am unaware of the aftermarket support for this engine stateside.[/quote]

I thought that adjusting compression with headgasket worked but is a poor choice.

[Rownan]

I am running an 11:1 compression KA and use 93 octane without a problem. I could have even gone a little higher I think.

JWT tuned my ECU to run it.

Timhttp://www.projectaspec.com

[JJ240]

ok cool. How do you think it would work without the ecu reprogram. I wouldnt be able to afford that till later this spring/summer

[WDRacing]

The head gasket is basically the same as having the pistons milled or adding material to your head. You might run into quench problems when decreasing your CR from stock. But since he's increasing I don't think he'll have any problem at all. You should be able to have a gasket made by just about anyone back in the states. I'm pretty sure FelPro will make one if you give them a stocker for a jig.

11.1/1 will be fine. If you notice any ping just retard the timing a slight bit. If your that worried about it, drop a little cash and have it dynoed, they'll tell you A/F ratio's and whether or not your detonating.

You can also run a can of NOS octane booster with every tank. I know it's good enough to add 2 psi of boost. So I'm sure it will more then cover your 11.1/1 CR if your already using 93 octane.

Best of luck...

WD

[JJ240]

OK, I decided to go with 11.1:1...I was hoping I wouldnt have to take the head off to do this job, but now I have to find out what grade it is. damn its time to go order some more gaskets

[JJ240]

As I was removing the crank tonight I realized I had forgotten secondary costs to replacing the pistons...new rings wont sit with a smooth cylinder wall. and I cant afford to have my head honed and crosshatched. This sucks!

[I am Technoman]

You cant buy a hone tool you know the kind that will go into a drill and do it your self?

[JJ240]

Hmm...didnt know that was something that could be done myself. No I guess I dont know what kind of tool that would be but I can imagine how much presicion is required?

[dreamsOfSkylines]

you chould do alky injection on a low setting, i think its only $400 for a set up. Its like having a tank of octane booster in the trunk.

[I am Technoman]

Hmm...didnt know that was something that could be done myself. No I guess I dont know what kind of tool that would be but I can imagine how much presicion is required?

A honing tool is a flexable brush looking thing that has alot of beads all over it. This tool will remove all scratches from your cyliner walls,but will not bore out your cylinders any bigger. This is just to clean the walls to allow new rings to seat. Go with the 99 Altima rings they are chrome and cost next to nithing.

[JJ240]

OK, I have been looking around on the internet...flex-hone cylinder hone tool sounds like the one youre describing but I cant seem to find one in 220-280 grit which is what should be used for chrome rings right? anyone have a link to somewhere selling a hone tool the right size for KADE in 220-280 grit?

[JJ240]

Actually the Flex-Hone is described as being a plateau finisher...so I would need something else to actually hone it before that was used. or does it work that work alone since I am only trying to seat new rings not bore.

[Movingviolation240]

dude let me tell you, don't use a ball hone for your motor, pay sombody to do it. The difference between somthing that gets a good seal and somthing that dosn't is the hone job IMHO. I always thought it was just a simple little job, it isn't. I listened to Rawl go off for over 40 min about all the ways you can screw up a hone job on accident or by ignorance.

[JJ240]

Yeah thats what I was afraid of. Well that trashes my plans. Im too poor to do it now and no way Im pulling my engine this summer again. Thanks for the input everyone it was worth learning

[I am Technoman]

I say use a ball hone, be confident man! You can do this. The most important part of honing is getting the top of the cylinder wall cleaned up “TDC”. If you cant find the right grit use stock rings. The way you pull the drill out with out stopping and put the ball hone back deep in the cylinder and then turning it on will not hurt your block after your first run through the cylinders wet the walls with marvel mystery oil and hone all four again JUST DON’T LEAVE IT IN ONE PLACE TOO LONG! Me and a friend rebuilt a VG30 a few years ago and we used a ball hone to seat the rings now that pathfinder has 89k on it.

[Dorifto-King]

Okay, im not to sure i'm understanding exactly what detonation is, is it the same as this high compresson ping i hear about, which i have heard is cause by the fuel mixture not combusting evenly, and thus causing some of the mixture to ignite after the required time? if so would a higher power Ignition system resolve this problem, if so what system would you suggest. Input pleast

[C-Kwik]

Yeah thats what I was afraid of. Well that trashes my plans. Im too poor to do it now and no way Im pulling my engine this summer again. Thanks for the input everyone it was worth learning

Have you actually priced it out? A friend and I rebuilt a Supra motor. Needed it bored, but he didn't want to pull the whole motor. We used a mobile service that many dealers use. They charged about $200 or so and most of that was becuase of the special equipment needed to do the job while it's in the car and to come out. I think if you take the block into a machine shope, it's not all that expensive. I've heard $50 but don't quote me. It was a while ago.

[JJ240]

Yeah, Im not sure the actual cost of having the cylinder walls honed would be that expensive, but I would also end up spending alot more getting gaskets and having the rings set in the pistons too. Just got the crank out this morning, Ill take it somewhere to be turned monday and Im not sure how big a dent that is gonna be in my wallet yet

[JJ240]

theres nothing wrong with detonation...its pre-detonation that is the problem, multiple ignition sources in the chamber lighting the fuel in different spots so it doesnt burn evenly can cause it to explode at the wrong point in the stroke creating excess pressure in the chamber which=bad...as I understand it the increased compression can heat edges making them hot enough to combust fuel. that may be partially or not at all right though.