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Old 11-26-2002, 04:18 PM   #1
dcoty
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Default N/A beast has rod knock! Tuning diddnt go well...

I know I was supposed to post a sucessful tuning of my car but...

My car has developed a bad rod knock following installation of the unichip. The rodknock developed while the unichip was still being tuned with under 50km being driven since the redline was raised to 7500rpm. I will know more details Wednesday night after the engine has been disassembled. More than likely the damage probably originated when the engine experienced severe knock and broke a valve while running the Zex kit. This thread talks about the damage from the Zex and and a list of my mods. http://forums.nasioc.com/forums/show...hreadid=247649

For the time being, I am probably going to replace the damaged engine with a stock engine and have my damaged block rebuilt. I can use this opportunity to build up a really crazy NA engine. 11-11.5:1 compression ratio, more displacement, balance, knife-edge the crank etc. I want the bottom end capable of 8,5000-9000rpm. Which companies make stroker kits for the EJ25 and how much overbore can be done safely? Is it necessary/worth it to go with a closed deck on a NA engine? It also needs to be capable of handling a 100shot of N20.

Anyway, im open to all suggestions and comments, thanks for reading guys!

Dan
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Old 11-26-2002, 05:23 PM   #2
BOY
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Dcoty, that sucks! I've been following your engine build and you were definately on the right track. I'd highly recommend closing the deck at anything over 10.5:1, EJ25s may handle 11:1 but my first block failed with stock compression! I also wouldn't recommend boring the cylinders, stroke it baby. I know Jun has stroker kits (if you're independently wealthy) or you could work with Paeco Industries. Good luck with the rebuild.
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Old 11-26-2002, 07:13 PM   #3
dcoty
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Hey, thanks for the encouragement! I need it.

I already have plans laid out that wil be started this week. There are a group of amazing guys in a place called Grandby near me and what is being planned right now is:

roughly 2.6 (maybe 2.63) litre block hopefully. With custom valves, custom pistons, rods, pins etc. Adding 4mm to the length of the rod too. All internals will be shot peened and built to last. It will also be capable of handling a 100 hp shot of nitrous from a direct port Nitrous Express kit. This is all prelimanary, but my aim with lachute is if everythong goes as planned, is 240-250 crank hp. Im looking for all suggestins from people. I will give the go ahead if my block is very messed up and its cheaper to start from scratch than fix the damage.

This wasnt planned to do until a year from now, but, im gonna see what I can do. This is an opportunity to go all out.

Whats everyones input on this? Im taking all suggestions!

Dan

Last edited by dcoty; 11-27-2002 at 12:54 AM.
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Old 11-27-2002, 09:02 AM   #4
BOY
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Depending on the cam profile (i.e. Cobb spicey) and a 7000+ redline you should have no problem making that kind of power. You may want to consider sleaving the cylinders for added strength and rebuildability (<-- is that a word?). My only suggestions are make sure the block is reinforced, use TI where possible, and take it easy on the engine management and you should have a screamer!
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Old 11-27-2002, 10:30 AM   #5
dcoty
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I forgot to mention sleeving the block, thats a good point. im going to use the strongest stuff I can find to put in there. Im not cutting corners becuase Ill end up in the same place I am now if I do.

Im getting a call today from lachute to tell me what kind of damage Im looking at, so im keeping my fingers crossed. I think te Unichip will be perfect for engine management, its not too overboard and Ben at lachute is a pro at tuning it.

Dan

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Old 11-27-2002, 12:10 PM   #6
HndaTch627
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Quote:
Originally posted by BOY
Dcoty, that sucks! I've been following your engine build and you were definately on the right track. I'd highly recommend closing the deck at anything over 10.5:1, EJ25s may handle 11:1 but my first block failed with stock compression! I also wouldn't recommend boring the cylinders, stroke it baby. I know Jun has stroker kits (if you're independently wealthy) or you could work with Paeco Industries. Good luck with the rebuild.
just alil FYI the Jun stroker kit is a 100mm bore and the same stroke as the stock crank, it's just balanced, knife edged, etc.

You really need to destroke the 25 is you want 8-9k RPM reliably out of it.

jeremy
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Old 11-27-2002, 03:32 PM   #7
Rob K
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Just to clear up a little confusion on dcoty's car, he is going to stay with the stock crank, so the only displacement increase will come the overbore (very small change). However the connecting rods will be 83mm long (4mm longer than stock). With custom pistons to allow for the longer connecting rods. This will bring the rod ratio up to 1.72:1 which is better suited to high rpms.
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Old 11-27-2002, 03:35 PM   #8
BOY
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hmmm, I'd think shorter rods would make for better high rpm performance. Either way, I wouldn't have thought of it.
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Old 11-28-2002, 02:56 AM   #9
HndaTch627
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Quote:
Originally posted by Rob K
Just to clear up a little confusion on dcoty's car, he is going to stay with the stock crank, so the only displacement increase will come the overbore (very small change). However the connecting rods will be 83mm long (4mm longer than stock). With custom pistons to allow for the longer connecting rods. This will bring the rod ratio up to 1.72:1 which is better suited to high rpms.
that's the exact opposite of what you want to do, a longer rod would correct for piston slap better but leaves less room for alumnium material. You want to target a 2800 FPM rod speed @ redline...you are going way past this by going with a longer rod, especially if you are going to spin it for 8-9k RPM.

jeremy
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Old 11-28-2002, 04:45 PM   #10
dcoty
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Im gald to have some good input here, thanks!

So, increasing the rod ratio would not be a good idea? I'm fairly new to this, but I see your point when it comes to a hight revving car. The reason I want to increase rod ratio is becuase having the wrist pin higher up in the piston will give the rod greater leverage, Im not very familiar with the in depth technical side of it, but that is the main jist of it.

But i would rather the displacement of my engine to stay at 2.5 litres and only rev to 8,00o rpm at the most, that will be more than i need. But If I wanted a 9,00 rpm screamer, i see how longer rods would be a bad idea

Im also coating the pistons to withstand a 100 shot of nitrous, i know coating isnt reccomended in a turbo car, but I dont think my EGT will be high enough to cause the coating to flake as it does in some turbo cases.

Anyway, anymore ideas and reccomendations would be great, the rebuild is beginning tomorrow and I get a free loaner engine for the time being.

Thanks for the replies!

Dan
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Old 11-28-2002, 05:17 PM   #11
HndaTch627
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are you going turbo or nitrous?? i am now confused, the cermic heat coating you get on pistons is to disperse heat evenly across the surface and not allow for hot spots in the piston to develop. The only issue is it also causes more carbon build up on the face of the pistons.

jeremy
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Old 11-28-2002, 07:37 PM   #12
dcoty
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Im definitly not going turbo, Im am putting a direct port nitrous kit from nitrous express on my car though, thats why Im am getting the pistons coated for nitrous use. Will the carbon build up potentially become a problem? Thanks fro your help, i want to do this right!

Dan
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Old 11-28-2002, 08:48 PM   #13
HndaTch627
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Quote:
Originally posted by dcoty
Im definitly not going turbo, Im am putting a direct port nitrous kit from nitrous express on my car though, thats why Im am getting the pistons coated for nitrous use. Will the carbon build up potentially become a problem? Thanks fro your help, i want to do this right!

Dan
dan you just gotta beat the snot out of the car once in a while w/o the nitrous running to clean some of the carbon off the faces of the pistons. I'm glad you are using a wet kit and a NX wet kit at that. I swear by their products after seeing the difference in quality between them and NOS. Good luck.

jeremy
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Old 11-28-2002, 11:03 PM   #14
dcoty
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There will be no problem with me ripping the car once in a while, i have a local track i go to (really nice circut) and I race against civic SiRs, intergras, mustangs etc, so it gets a good long time to get rid of the carbon deposits.

Im glad I have a second opinion about Nitrous express, I have heard nothing but the best about them. the nitrous will only be used occasionally though (every day lol).

Thanks for your advice, and if there is something you would reccomend doing to the engine while its out, let me know, so i can mention it to the guys working on it (they start tomorrow, it'll be 4 weeks until its finished). Thanks again (every thread about my car you have given me great advice).

Dan
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