Spoon Headgasket - K20

[DownTheHatch]

Would it be safe to install this high-compression head gasket?
It's thinner than stock to raise compression a few points.

http://www.jdmhondaparts.com/spoon/s...headgasket.jpg

[myeverlovinsir]

From what I understand about toda, and their philosophy, race
engines need improved head gaskets when it comes to a higher
compression engine. (when you decide to go with higher comp.
pistons) I Don't know what the specs are on our original gasket
compared to this one. any idea?


I would also like to know what the valve clearance(probably interference) is (when large lift engaged)
from our TDC as stock.

[!@#$%]

i can see it now....
oooOOOOoooOOO this head gasket is for the k20a2! k20a3 doesnt rev like a real engine....blah blah only the good stuff gets REAL parts...:(

stupid k20a2....making our engines look slow

[JSIR]

ooh, that is interesting, extra compression is always a good idea even for our motor - should bring our compression ratio up to about 10.1 :1 if not a bit more. Stock is a measely 9.8:1.

[IceD out N CALI]

would our pistons be able to handle the extra compresion?

[JSIR]

not a problem, lots of clearance , still very safe

[nikkotyper]

Hey, JSIR this is a little bit off topic but would you mind writting up a little more on your TB bore. I was wondering if you did the bore yourself what happened to the butterflies? Did you have to customize them as well?

[JSIR]

Originally posted by nikkotyper
Hey, JSIR this is a little bit off topic but would you mind writting up a little more on your TB bore. I was wondering if you did the bore yourself what happened to the butterflies? Did you have to customize them as well?

well since you asked here it is, maybe someone may want to move this to a new thread. I removed the throttle body myself (TB for short). I took apart the first pulley on the throttle shaft to make it easier for the machine shop I was going to use. I took off the removable sensors so they would not get damaged, there were three of them that came of very easily. These new Honda TB's have lots more parts on the pulley than the older ones due to the cruise control. I measured the stock resistance readings of the TPS sensor as you have to return the sensor to the stock setting after reassembly. Upon reassembly the TPS sensor will be adjustable so you can reset it easily. The stock TB is a 62mm bore at the butterfly.

It was my expectation to go up to 65mm on the TB, 3mm over on the bore, but when we got it on the milling machine we noticed that there is a sealed bearing for the throttle shaft that is close to the edge of the bore. The most we could go over was 2mm, thus the new TB bore is 64mm. When I pulled off the stock TB I started opening up the bore on the intake manifold expecting to go larger on the TB, so I opened it up to 65mm. The stock opening is just about 64mm so I could have left it as was and it would have worked good, but I went up to 65mm before I found out the TB could only be opened up to 64mm.

So I have a 64mm bore with new butterfly to match. I had a friend of mine do the work as he owns a race machine shop and I dyno there as well. Him and I came up with the idea to put a radius on the leading edges of the TB bore. The walls of the TB are very thick on these TB's so they have a flat thick edge to them. We radiused them, so the leading edge looks like an air horn velocity stack design. This is kind of unique as most people just taper out the bore to a thin edge, mine is radiused. Apparently air likes to flow over rounded edges more than flat straight edges, so we decided to do it. It looks very nice IMO. I think it works very well also, as I gained 3-4 whp at all rpms above 3000 rpms with no losses anywhere, pretty impressive for only a 2mm over bore. I reset the TPS sensor when I got it back and reinstalled the throttle shaft pullies and some of the sensors that I removed. Then I just installed the TB and we were off to the races. I can take pics when I swap my intake in the near future. The gasket on the back of the TB seems to be permanently glued to the back of the TB so it does not get removed unlike Honda TB's of the past, be careful not to tear it.

Car runs good, idles perfect, decent gains. I only paid $150 Canadian for the work, which is about $100 US, and they did a nice job. The idle stop screw gets adjusted with a new butterfly plate, which they do for you, but I can play with it myself as well if needed, no biggie. They counter-sunk the two screws that are on the throttle shaft for smoother/improved air flow, as they are raised on the stock shaft. Turnaround time for me was about 3 days, using a local shop. Worked out well for me.
hth

[myeverlovinsir]

Great post Joey, I will be getting arround to doing this after
hondata has had thier kick at tuning and use F&F for the TB.
Sounds like they have their shop in order, and now that they have done yours, a repeat will be a snap. tks

[myeverlovinsir]

Originally posted by JSIR
not a problem, lots of clearance , still very safe

btw, how did you come to the conclusion that we have enough
clearance for this thinner gasket? Taking into consideration that
we have +/- 25 deg on the valves during overlap, and when at
TDC would this not interfere? Pls explain. I guess this gasket would
only save about 1-2mm at best from stock but do you have any
data on the stock gasket? Just a thought, I am a little hesitant to
try this outright and would like more insight. tks.

[JSIR]

well the gasket is made for the k20 engine, whether it is the RSX-S motor or the Civic Si motor they both feature cam timing advance in the same amount of degrees. Spoon has already tested it thus it will work fine otherwise they wouldn't sell it. Plus stock Hondas have a lot of clearance between pistons and valves. Our pistons don't have much of a dome on this low compression setup, smaller than the RSX-S pistons. On my last b16 I installed Civic Type R - high domed pistons-, milled the head, and had a thinner head gasket, and still had lots of clearance while advancing the cam gears about 10 degrees either way. These Honda gaskets are typically about .028" in thickness, when they are reduced to two layers they lose about .009" going down to .019" thickness. Honda would never have an engine where the pistons are .009" or less distance away from the valves. You will probably find that the valves and pistons never get any closer than .080" on a Honda engine, if not more. I haven't seen any measurement stats on the k20 engine, (and we never will) but I can't see Honda changing anything in terms of clearances.

[myeverlovinsir]

Originally posted by JSIR
well the gasket is made for the k20 engine, whether it is the RSX-S motor or the Civic Si motor they both feature cam timing advance in the same amount of degrees. Spoon has already tested it thus it will work fine otherwise they wouldn't sell it. Plus stock Hondas have a lot of clearance between pistons and valves. Our pistons don't have much of a dome on this low compression setup, smaller than the RSX-S pistons. On my last b16 I installed Civic Type R - high domed pistons-, milled the head, and had a thinner head gasket, and still had lots of clearance while advancing the cam gears about 10 degrees either way. These Honda gaskets are typically about .028" in thickness, when they are reduced to two layers they lose about .009" going down to .019" thickness. Honda would never have an engine where the pistons are .009" or less distance away from the valves. You will probably find that the valves and pistons never get any closer than .080" on a Honda engine, if not more. I haven't seen any measurement stats on the k20 engine, (and we never will) but I can't see Honda changing anything in terms of clearances.

Granted, you have shed some light here. Although I think someone will have numbers
on the K20. Never say never. I think this is a viable mod and
am gonna ask some more about what is required to do it. This is
obviously an advanced engine mod, and will do my best to understand
all the steps involved before doing it. (or getting it done)

Thanks again Joey for lending your valuable insight.
You are a true credit to this site!

Glen

[JSIR]

thanks for the kind words Glen. I've done head gasket mods many times, they are a nice mod, the gains are relatively small but still a gain. Basically you gain 4% in power for ever 1 point increase in compression, thus on our cars going up .3-.4 of a point is probably worth 1.5% in power or just under 2%. Mabye 2-3 hp max. When I've done them in the past you feel the bottom end torque gain more than the top end.

I could swap out the gasket in about 6-7 hours in my garage using basic hand tools and taking my time, but I need to get a Honda shop manual - my next purchase for sure. If you had to pay someone else to do it, it would not be worth the gains - it would cost about $300 in labour, plus the cost of the gasket, new coolant fill, oil and filter change, misc. gasket sealer and parts cost. You are probably looking at $600 in Canadian funds plus taxes for a shop to do it. Even more expensive if you replace the head bolts and don't re-use the original ones. kinda pricey.

[myeverlovinsir]

Tks Joey, I just ordered a honda shop manual today, will be about
90 bucks but will reap the benifits and share the rest.
Am gonna do this mod, well worth the effort IMHO.
Also had a quite involved chat with a tech at honda, my most
respectable resource at my dealership. He was explaining to me
how large lift occurs at about 5000 rpm! Very detailed, he just
got out of school at honda. I kept saying are you sure? And
was very clear about this. Basically fuck hondata, and what they
say about the RSX base. Does not apply.
Large lift occurs where I suspected, at near 4800 rpm.


Also learned another thing about EGR, it is simply a regenerative
system with hoses, a closed loop if you will, that is par with previous
honda applications. Simply recirculating crankcase emmisions back
into the intake. This would explain the carbon buildup and
particles I and yourself have noted in the intake manifold.
hth

[JSIR]

ah ha ! I knew it, that makes a whole bunch more sense now. But that exhaust valve lock up description along with two intake valves doesn't sound exactly right, not sure how that would work. And last time I looked at our intake cam it only had two lobes per cylinder, not three which I was hoping for. But anyhow that does sound better to what we were hearing from Hondata and the RSX people. Cant wait to get my hands on a shop manual. I am interested to see how complicated the timing chain system is, that is probably the hardest part of a head gasket installation, understanding how the timing chain is removed, reinstalled and tensioned on these new engines. The b-series engines were pretty easy to work with in that respect with their rubber timing belt.