I have been fighting this stuff myself so I am happy to pass along some of my own concerns. I just wish that every once in a while a Honda engineer would be sent down from heaven to say: “I have consulted with the effervescent Sōichirō and he says that the dome displacement of a PCT piston is and forever will be 8.33cc per dome, so he says, so it is.” or some shit. Here are the pertinent questions as I see them:
What is the true center-center rod length in a B17?
Zeal says 132mm, Endyn says 5.208 inches which converts to 132.2832mm which doesn’t seem like much difference, but adds .27 CR.
Is the PCT piston really 8.63cc dome displacement or is it 6.15cc as some people claim?
This is a .73 difference.
Does the stock head gasket compress to .029 inches or .026 inches?
That difference is only .12 CR points
How much does/did decking the block and resurfacing the head take off on your application?
Every .002 inches is 6 points.
Why do the online calculators show a stock B17A1 configuration as having a 9.5:1 compression ratio instead of the advertised 9.7:1 ratio? Bad advertising or are the calculators missing something?
The main problem is not knowing. In your situation, if you kept those pistons, you could lower compression by getting a slightly thicker head gasket and then even more by increasing the volume of the combustion chamber but if your compression really is 11.5:1 or something like that right now, then you certainly wouldn’t want to lower it to 10.5:1 by doing that stuff!
I am not an engine builder and don’t pretend to be, but if I was in your boat, I would assume that the higher (8.63cc) number was correct and then just measure your piston to deck height manually. With those two numbers, as well as an approximation of how much your head has had taken off of it, you should be able to use the C-speed calculator to figure out a decent approximation of your compression ratio and you don’t need to know the actual measurements of the rods or compression height of the piston.
And honestly, when it comes down to it, it is the actual compression pressure in the cylinder that is the actual problem and the thing that will lead to detonation (assuming there isn’t any mechanical interference) so maybe there is a way for you to check that? That pressure can also be changed to some extent with your cam timing.
Anyway, that’s all I’ve got, hopefully it will help you find a place to get started - I think for my build, I’m going to just get JDM ITR or JDM P30 B16A pistons and using a stock head gasket just mill the head until it is at a reasonable compression ratio somewhere between 11:1 and 11.5:1.
hahaha thanks Dave for the support:) Its nice to hear. OK so after bondo and primer. I ran into a snag. I thought my job was decent but not great so I had my nephew come over(who graduated from wyotech for autobody and paint:D) and got his take on my job. He re did my areas and made it look even better… I know on to the pics right???
all credit goes to my nephew TJ:) I am very pleased. Paint to come tonight and tomorrow> Stay tuned as a new color will be revealed soon:ohyeah:
so here is a sneak peek. This isn’t the finished product by anymeans… paint code B545P-S for those of you who were curious. (Laguna Blue Pearl from 09 S2K)
ok ok here are 2 pics and more to come late tomorrow evening when hopefully the engine bay will be finished!!
Coming along wonderfully Please tell me you’re doing the whole car in that color and not doing the typical west coast thing of doing the bay a different color. That shit got gay, QUICK.
glynn- thank you sir. This all started with my 12 yr old niece. she asked me why i was keeping it gray. since i’ve had 2 vehicles that color. So i said what should I paint it? Then my wife spoke up and said how bout Dave’s car? (which is my friend who use to be on g2ic and now has a 09 s2k laguna blue. The more I thought about it the more sense it made… and now the choice is final
Jake & ominous- your are correct I will be painting the whole car Laguna blue:D Im excited and nervous. I hope it all turns all good:)
Thank you all for tuning in and checking out this project
[QUOTE=.J.;2198840]I like it Ryan, I take it you’re doing a full color change including interior painting and undercarriage pieces?
Great update!
J.[/QUOTE]
Thanks J:) So I talked with dan and found out my cr is around 12:5 to 1 so before i continue with my motor build ill have to figure out what i’m going to do to bring the cr down somewhere in the 11’s range. Dan gave me a few ideas that im thinking about.
I guess i should be more specific when I said im painting the whole car. While yes I do have most of the interior out. The dash board, fuel lines and wires have not been removed. I dont plan on painting the whole interior. I figured id do what I did last time when it was painted GGP. Ill make sure the door jams, door sils and trunk sills are painted like last time. I think the difference this time is the engine bay. Last time there were many things I didnt remove(ie, brake master cyclinder, abs, etc) so there was a lot of unwanted overspray. This engine bay and the whole part of the front frame will all be Laguna blue. I hadnt given much thought to painting the undercarriage.I think removing all the dirt grease and grime from 20 yrs would be a whole lot of work. I think for now Im going to do the same as last time. although this time Im going to remove a lot if not all of the old existing paint on the outside of the car. I want this paint job to look as good as the ggp did:)
Ry,
No one, and I mean NO ONE ever says: “I wish I didn’t bother to do all of that extra work” once a car comes out of paint looking perfect! Do all of it, pull it all! I can count 5 maybe 6 guys who literally had an almost perfect color change but who bothered to take a car back into the booth for the misc. areas they didn’t think they’d care about later on down the road.
Thick-ass Cosmetic head gasket and compression should be down to something reasonable.
haha J the feeling is mutual buddy! If only I lived next door to you then I could implore your services on a regular basis;) car related ofcourse
yea- I know what your saying on the paint. Im not sure if i’ve ever mentioned this. But this gsr will be owned by no one else anymore but by me and my wife:). With that being said I can see why I should paint everything inside and out. Ill definitely have to look into doing it.
And yes thats what dan recommended and to me since Ive already had these beautiful pistons installed and the block work done. I think the smartest and most cost effective idea would be to use a cometic head gasket!!! bye bye 12’s and hello doable 11’s:)
Btw my transmission says thanks for the upgraded parts;) you da man .J.
Looks good dude, and I’m w/ J, paint the inside, you definitely will not regret it. Especially if you ever decide you want to strip out some of the interior…
I am very pleased. Paint to come tonight and tomorrow> Stay tuned as a new color will be revealed soon:ohyeah:
Please tell me you’re doing the whole car in that color and not doing the typical west coast thing of doing the bay a different color. That shit got gay, QUICK.