[sudo chop]

Hello everyone, I feel a little rude that my first post is asking a question, its always a little annoying when people do that, but hopefully you guys will be kind enough to help me out, I promise I will be back to contribute to the forum.

I am trying to thoroughly plan out an NA build of my D16Y8 in my 00 EJ8, and up until yesterday, I hadn't even considered touching the compression, but after messing with a couple of compression calculators it looks like I can pull something like a 10.6:1-11.0:1 CR, depending on the accuracy of these calculators, up from my stock ~9.6:1, just by tossing some PM6 pistons into my motor. Sounds like a no brainer!

The thing I am worried about is valve to piston clearance, especially since I am def getting a stage 2 Crower and am toying with the idea of going stage 3 if the outrageous lift isnt gonna cause a valve clearance problem.

SO, I am hoping you guys can help me get this question answered: What kind of valve to piston clearance will I have with PM6 pistons in a D16Y8 engine? And will it be enough to run a high lift (442/468 ) cam?

After scouring the internet for the past several hours I can't find a singe thread or article written in the past 4 years that even comes close to giving me a sound idea.

TIA!

 

[The_Acid_Beaver]

You really need more compression to get the benefits of running a stage 2 or especially the Crower Stage 3. There are very few D-series engines that will ever have P2V contact problems with reasonable cam gear settings.

You really should be aiming for at least 12:1 compression. Using PG6s from the 86-87 Integra and a stock Y8 head and gasket, you'll get ~12.7:1 compression. That's the kinda setup you could really use for that large of a cam.

 

[sudo chop]

You really need more compression to get the benefits of running a stage 2 or especially the Crower Stage 3. There are very few D-series engines that will ever have P2V contact problems with reasonable cam gear settings.

You really should be aiming for at least 12:1 compression. Using PG6s from the 86-87 Integra and a stock Y8 head and gasket, you'll get ~12.7:1 compression. That's the kinda setup you could really use for that large of a cam.

Ok, great, thanks for the feedback.

But 12.7:1!!! That sounds like wayyy too much! Would I even be able to run pump gas with that? I am just grabbing CRs off of wikipedia here, but arent the ITRs only at like 11:1?

Is there any build you know of that used that setup? With the PG6s?

Thanks again

 

[The_Acid_Beaver]

Joseph Davis, a well respected tuner, built an engine with 12.5:1 SCR (Static compression ratio) that runs on 87 octane. IIRC, the head he used shares the same combustion chamber as your Y8 head. He used PDN pistons, from a 98-00 GX. You can read about his build if you search for a thread entitled "Any 87-octane high compression experience" or something to that effect. Others have successfully built engines witht he PG6s, but you won't find that info on forums. At least not usually. It takes a bit of digging around with google to find info.

13:1 SCR is high, but entirely possible on pump gas. You just have to be bold enough to do it and do it correctly.

It might not be a great idea for your first build, but, there are a number of people who have built PM7/Y8 combos that run on 93 octane. Those pistons suck. The PG6s or PDNs are much better designs. They have a higher compression hieght and lower domes which allow for better combustion dynamics. (And higher comression ratios without detonation).

So, my conculsion is if people can keep together a Y8 head and PM7 piston combos together with a good tune on 93, a PG6 or PDN piston and Y8 head combo will run better, faster, on less octane with less hassles tuning!

 

[1.5Slowmatic]

Just remember that if you use the PG6's, to clearance th valve reliefs in them

 

[sudo chop]

Well guys, this build is mostly meant to be a learning experience for me, and I will be tuning myself, so I think I should keep it conservative. Reading Joseph Davis' build thread, it seems to be nothing but him expertly dealing with tuning obstacles at that high CR. I don't think I'll be able to handle that kind of stuff, not this time anyway. I guess I'm saying that if I don't break new ground in the NA D16 power arena, I will live. I would much rather have a build that is safer and easier for a noob like me to tune than lay down huge hp.

So having said that, I think I will go with the PM6s and the stg2 cam.

FYI, just in case you guys have some more advice for me, here are some of the other things that are planned to be in this build: mildly ported used head I picked up for cheap, 60mm B16 TB, my stock IM port matched to head and matched to the TB, and uhh maybe I can find a cheap/used header, and of course I have intake and exhaust.

You have been really helpful, thanks.

 

[1.5Slowmatic]

Honestly, do the PG6's. For our little motors thats not that high of compression. And with the small dome you have some error room. As for the IM, DONT port match it, leave it alon or read my thread about how im porting a z6 manifold plenum. If your going to port match anything, do the intake side of the head and the header, and thats it. And id honestly keep your stock TB, you dont need the 60mm

 

[The_Acid_Beaver]

Don't port match. Ever. Portmatching increase flow BOTH ways (in AND OUT). You want mis-matched steps to keep the return pulses from the backs of the valves inside the port, the runner, and the plenum. A 60mm TB is too large. A stock sized TB with the plenum opening opened up to about a 4mm mismatch can actually see a positive pressure develop in the plenum. The second you port match, that advantage disapears, efectively making your intake part of the plenum and really jacking with any resonant Tuning advantage you had previously. Positive pressure in the plenum will always out perform a higher flowing setup across a wider part of the window of operation of the engine. Portmatching does work for maximum power gains in very small windows of operation, however, this is not so good on a street car. Increasing torque over a wider area of operation is going to make the car more usefuly faster on the street.

Another thing I would recomend doing that won't severly increase your compression, but still bring it up a bit is zero-decking your block to the PM6s. This will require about .5mm to be whacked from the block. This will take you to the lower side of 11:1. That is safe. It won't be much more difficult to tune, and your engine will thank you for it, especially with a bigger cam.

 

[sudo chop]

slow, I read through your z6 porting thread, but I cant see the pics. Anyway, I guess I will just have to trust you guys about portmatching until I learn it on my own. I see what you are saying though about the stepping keeping pressure on the stepped side, makes sense. Would opening up the ports on the runners just a little bit, but not as much as the ported head, to keep a step, be good? Or just leave them alone completely? So you are saying to open up the IM at the TB to be bigger than the TB, and then to open up the header to be bigger than the exhaust ports?
Well you guys both sound like you know what you are talking about, so I'll listen up.

If you think I will be able to handle the PG6s at ~12.2:1, then I will do those. Like I said, I am only worried about having too hard of a time tuning as a beginner, but if you guys don't think it will be too bad then I will do it for the power.

I am definitely getting put in my place right now lol, I thought I had all of this stuff figured out.

Also slow, what you said about the valve relief clearance, you mean just to check the clearance right? You dont mean I will physically have to modify something on the domes do you? If you do.. well it doesn't really sound like something I could handle, bc again, i r noob.

 

[The_Acid_Beaver]

Start tuning what you have now. Add some parts to what you've got now, then re-tune. Get familiar with tuning first, then build the engine, and tune that. Seriously, if there are a bunch of guys running around with a lot worse piston/head combo than what you plan on doing, I am sure you can manage. You really don't seem like an idiot. =)

I personally don't think you are going to have much of an issue with p2v (piston to valve) clearance with the PG6s, but that is the only real concern for them, especially with the compact combustion chamber of the Y8.

Yes: Port the TB opening bigger than the TB, match the head to the intake manifold gasket, and port out the header. That would be golden.

 

[sudo chop]

Thats for the encouragement.

Yea thats pretty much my plan, I am going to try to replicate my P2P tune on the chipped P28 just to get warmed up to tuning on my platform. I plan on getting lots of fancy booklearnings from a lonnnnng shopping list of tuning books before I get to that point, so hopefully I will be ok.

So, since I am settled on the PG6s, the crower stage 3 would probly be a pretty good choice, no? From what I can discern of preventing detonation with high CR, a high lift cam is the place to be. There is still that concern of p2v clearance, even though I DO hear you keep saying it shouldn't be a problem. With the high lift and long duration, coupled with the higher comp height and more dome... idk, cuz idk really what im talking about practically, but on paper that sounds to me like cause for some concern. What do you think? Like I said before, I cant seem to find anywhere where someone has posted the detailed results of such a build, so advice from you guys on this forum is really my only alternative to going into this thing blind and taking my chances.

Anyway, your help and guidance thus far has made a huge difference, thanks for taking the time to spell it all out for me.

 

[1.5Slowmatic]

what program do are you tuning with. I suggest downloading crome and familiarizing yourself with it so you can understand what your are playing with, thats what i did

 

[sudo chop]

Yea man, thats the first thing I did when I thought I might try tuning myself. I got a base bin from a friend and started messing with the plug-ins etc. Yea, I suppose its better to get familiar with it then rather than when you've just fired up your car with the new ECU for the first time lol. Freeware FTW.

Thanks for the tip.

 

[The_Acid_Beaver]

You won't be doing anything blind, or at least I hope not. Of course you should check your clearances, and worse comes to worse, you get the valve reliefs opened up a tad. It's not anything rediculous. However, even with a huge cam, most people don't have issues any P2V contact in other engines. There is a LOT of P2V clearance in these engines.

Choo can do this, meng!

 

[sudo chop]

Awesome dude, thanks for all of your help, and the encouragement.

I can't wait to get started on this build, I am so excited. Just as soon as I get back from this deployment (4 days!) I am going to go at it hard. I will come back here and make a build progress thread to keep you guys updated once I start, I am sure I will have more questions anyway.

 

[1.5Slowmatic]

ive heard of people having issues on the PG6's even with stock cams. Id go ahead and clearance them no matter what just to be safe