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**MikeM@Ztune** · 03-12-2009, 11:17 AM

Originally posted by malibusst View Post

hey curt, what type of pistons are those??? ive had problems with CP's and wiseco's as the thrust side of the pistons tend to " wander " and scratch the cylinder wall... the common fix to this problem is to machine the sides of the pistons ABOVE the rings on a taper... in other words, put a taper on the pistons, about 8 degrees, all above the first ring...

Are you talking about damage from piston slap? That should only occur if your piston to cylinder wall clearance isn't correct. If your block is machined properly to the specs of your piston kit, it shouldn't be a problem. Machining off your anti-detonation rings to put an 8 degree taper on the top of the pistons doesn't sound like a wise idea to me. Does Wiseco condone this?

In terms of your scoring Curt, does Rob think it's due to the pistons, or debris from the broken valves?

**jdmtypes** · 03-12-2009, 02:37 PM

Originally posted by MikeM@Ztune View Post

Are you talking about damage from piston slap? That should only occur if your piston to cylinder wall clearance isn't correct. If your block is machined properly to the specs of your piston kit, it shouldn't be a problem. Machining off your anti-detonation rings to put an 8 degree taper on the top of the pistons doesn't sound like a wise idea to me. Does Wiseco condone this?

In terms of your scoring Curt, does Rob think it's due to the pistons, or debris from the broken valves?

I have Wiseco pistons in my block & now I'm starting to worry that they are NFG. My block was professional built following the proper clereances as per the specs for the pistons, am I going to be ok or will I have scoring like Curt's block???

**curtisgoodman** · 03-12-2009, 02:53 PM

Rob said that there is 20 thou difference between the piston skirt and above the top ring for clearance also a 5 thou piston skirt clearance to cylinder wall which is 25 thou gap between the wall and the top of the piston... regarding valve bits and pieces making that scoring there is no relation between where the most valves broke and the scoring... the most scoring on 1, 5 & 6 and the most valves broken were on 2,3 & 5... so you'd think more scoring be on those cylinders... who knows it could have been related to the couple on injectors that weren't up to snuff and are getting sent out... anyways i hope to god that this doesnt happen again and im sure we'll take all the precautions to avoid this from happening again...

**curtisgoodman** · 03-12-2009, 02:58 PM

Mike with tolerences that tight Rob said piston slap does not occur in the engine as long as i let the engine warm up before heavy use which is a no brainer... the only way besides outside contaminates that scoring would occur is when the mixture is lean and the top heats up more quickly then the sides and bottom of the piston and it touches the wall even with those large clearances it seems almost impossible that it would happen... i dont have an answer and neither does Rob which concludes that we cant 100% determine the cause of the scoring...

**MikeM@Ztune** · 03-12-2009, 05:14 PM

Hey Curt, looking back over my pictures of the heads and talking to Rob, even the cylinders that didn't have broken valves still had bent valves with piston and head damage, so there was definately debris in all 6 cylinders. The scoring on the walls is due to debris, not a piston or tuning issue. There are zero signs of detonation or excessive heat, and your car was still tuned very conservatively for break-in.

Wiseco has been making pistons a long time, and they are good pistons. We've built RBs, VGs and VQs with them, and we are using them in builds we're doing for our personal cars...there shouldn't be any quality concerns on the piston kit, and Rob verified that the piston and block clearance is to spec. As long as engines are built to correct specs, thrust is not an issue. Rob and I both feel that machining an 8 degree slant on the piston top would be a bad idea as it already has plenty of clearance in stock Wiseco form.

We have worked on race engines with Wiseco pistons, and had the opportunity to disassemble them after several races. Race blocks are built to looser tollerances due to excessive prolonged heat and expansion. Because of this, they are expected to have more piston slap than normal, and the specific wear and location is different than what is in your engine.

It doesn't take much to get between the piston and cylinder wall to cause light scoring. Luckily the engine wasn't running after the bolt broke, so the scoring is minimal, and rob was able to clean up the cylinder walls. I wouldn't worry about it being an on-going issue as everything will be put back together nice and clean!

**curtisgoodman** · 03-12-2009, 06:00 PM

thanks for the info Mike i wasnt bashing what you were saying just adding to the comment and such...

**MikeM@Ztune** · 03-12-2009, 06:37 PM

Originally posted by curtisgoodman View Post

thanks for the info Mike i wasnt bashing what you were saying just adding to the comment and such...

Oh ya, no worries, I just wanted to follow up and clarify after reviewing the details with Rob!

Piston thrust issues can cause a friction wear mark mid cylinder, but there were a few actual scratches on yours above the ring travel, which is definately debris.

I'll give you a shout soon to go over those other details we were talking about. Sorry I've been slow to get back to you lately, I've been out sick a fair amount the last couple weeks. Injectors are out for testing though, so we should be all set to get everything back together once we get the engine and injectors!

**curtisgoodman** · 03-13-2009, 10:42 AM

Sounds good Mike can't wait for that to happen! I'll chat with Rob today to see how far along he is... the engine should be ready for assembly.

Rob snapped some pics of the build again this round lets just hope he didnt format his memory card on his camera by mistake this time

Pics to follow!

Curt

**curtisgoodman** · 03-18-2009, 11:28 AM

So Rob has the bottom end together now after needing to replace an oil squirter that was damaged... now the valve setting job is at hand then it'll be back together and sent out for re-install... can't wait for round 2 it's been awhile now

Good things come to those who wait. (hopefully)

**MikeM@Ztune** · 03-18-2009, 11:40 AM

Hey Curt, Deatschwerks has sent a brand new set of injectors, and they should be here in a couple days!

A couple of your original injectors were off spec as per the tests. The owner of Deatschwerks called me himself to ask how long they were in use and what fuel they were run with because they have never had their injectors go out of spec like that. They are disassembling and testing them to see what caused the flow problem. He will let us know the outcome shortly.

Mike

**curtisgoodman** · 03-18-2009, 02:41 PM

Nice thats great news... the car only ran just shy of 2000 km's and i only ever put Chevron 94 premium octaine... I'm not sure if there is ethonal blended in the Chevron 94 but i never ran Mohawk ethonal 94 i heard bad stuff about it...

Hey Mike when you get the engine next week how long till it's back together... how busy are you guys next week?

Keep me updated!

**curtisgoodman** · 03-23-2009, 11:22 AM

Engine should be at Ztune today and hopefully they're starting the reinstall. I'll update everyone as i get info.

**curtisgoodman** · 03-25-2009, 03:23 PM

head porting pic...

**curtisgoodman** · 03-25-2009, 04:19 PM

more pics

exhaust before

exhaust after

intake pics

Enjoy the work of Rob @ Alec's Automotive Vancouver B.C.

**MikeM@Ztune** · 03-25-2009, 04:28 PM

I'll take some more less blury pics of the porting for you once it's on the engine stand! Hopefully getting started on it in the next couple days!

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