Does anyone know where i can find flat face valves for the A20A3 head? I've tried googling around and i cant find anything thats actually made for the A series.
OR if i can use some that are made for a different car...I'll go bigger if i can.
Does anyone know where i can find flat face valves for the A20A3 head? I've tried googling around and i cant find anything thats actually made for the A series.
OR if i can use some that are made for a different car...I'll go bigger if i can.
Last edited by Susanoo; 06-12-2011 at 04:51 PM.
1989 Accord DX converted to EFI and OBD1 on P06 Ecu using Hondarulez RTP
Blaster 2 Coil, Pacesetter Headers, 4G Injectors, 4G Alternator, Skunk 2 B18 ITM, Skunk 2 68mm TB, Delta 272, Xenocron 255 FP, wire tuck, fuse box and battery relocation.
Originally Posted by Susanoo
There aren't any off the shelf, you would have to have them custom made. And having flat faces makes virtually no difference in the compression ratio on these heads because the combustion chambers are so large.
I had a set of custom oversize valves made by SI Valves and they were about $33 each. I have yet to finish the head they're going in though.
C|
there is a great write up over on prelude power on how some guy used different valves from other cars on his head build. I dont know the link but maybe some one can help us out
1989 Honda Accord LX-i
B18c1 swap since 7/2011
175whp and 132tq
Redzone tuned
Yeah i just saw that . he used z6 valves and made some custom Guide. I forgot LOL. But IT wont make any different in comp ratio. Unless in my point. Only gain is by getting over sized valves for better flow. Shave the head a bit. My i ask why you want to do such thing?
200+ ALL MOTOR LS VTEC
Well I want to increase the compression and see just how much HP I can get out of this motor. :P I was told by a couple people and some websites that flat face valves could increase compression a little.
EDIT: Also im going to be using the injectors from the fouth gen accord... I recently found out that the head i had checked by a "quality" place is totally fucked, CYL 1 & 2 has bent intake valves. So obviously im gonna get headwork done very soon and i want to get it all done at once since im sending it to a specialty shop that only does headwork. So give me some ideas that could increase HP and torque please?
Last edited by Susanoo; 07-02-2011 at 07:58 PM.
1989 Accord DX converted to EFI and OBD1 on P06 Ecu using Hondarulez RTP
Blaster 2 Coil, Pacesetter Headers, 4G Injectors, 4G Alternator, Skunk 2 B18 ITM, Skunk 2 68mm TB, Delta 272, Xenocron 255 FP, wire tuck, fuse box and battery relocation.
if you are going to keep it NA you are going to have the port and polish the head. how much compression are you going to run? im going to be interested in how much power it makes.
1989 Honda Accord LX-i
B18c1 swap since 7/2011
175whp and 132tq
Redzone tuned
Rjudgey has made a few posts as to the nature of porting and results of porting and oversize valves on these engine. I would do a search for his posts and start reading.
Theoretically flat faced valves will increase compression, just not very much. Like everything else it comes down to cost vs. benefit. I tried to calculate the difference once and it was miniscule. There is also some thought that having a dish in the valves actually helps the intake charge circulate inside the combustion chamber, but that gets into some pretty esoteric concepts.
Also, when I ordered my valves from SI I requested flat faces if possible, but ended up with normal dished ones. The problem with these heads is that the valve sizes are backwards from other *normal* 2 and 4 valve heads. With 2 and 4 valve heads the intake valves are bigger than the exhausts, but on 3 valve heads the intakes are smaller because there's 2 of them. This means that the selection of valve blanks that the valve mfgs have to choose from is much fewer.
Rjudgey's old posts are a good place to start. Where are you planning to send the head? Do they do a lot of imports?
C|
I wouldn't worry about flat valves this will make you next to no power gain, on any engine the bigger the valves the more power you will make, I have a stock A20A3/4 block which is just blueprinted and hand built by me with a fully worked A20 head with big valve conversion and 272/285 degree camshafts, only major mod is custom inlet manifold with Twin Weber DCOE 45's which are modded as well but all this is with a stock cast header ported and flowed and crappy old downpipe with 2" collector and joint and 2.25" crush bent rubbish system (no Cat) still puts down 200bhp at the fly wheel. The extra power is in the head on these engines you won't gain anything significant by increasing CR ratio by .1, best to start with head then later on invest the money on a high compression bottom end once you've sorted out intake, exhaust and head. That way it will compliment each other much better and you'll see much more of a power increase then.
If i went and had custom 83mm flat top pistons made, had the block shaved .5mm and then head shaved 1mm then put my Big valve A18 Prelude head on for good measure my CR ratio would be around then 12.5:1 area and if i combine this with a decent custom exhaust header and 2.5" mandrel bent system I should be good for around 240-250bhp and around 175lbft of torque.
Yea i've been doing some reading about flat face vs dish and a lot of people say the dish give better flow and weigh less...
Thanks for the info, makes sense. I guess i'll just stick to the dished since it will be cheaper and if I get no gain from flat face then why pay the extra right? :P
Yea i'll search for his posts and read up. Im planning on taking it to a place called "Headworks of Nashville". My neighbor referred me and hes also a certified mechanic, plus my neighbor does really good work and I trust his judgement. Im not sure how many import heads they do. I could ask....I have to call back soon anyway to ask the parts guy what they can get for my head. :P
Thanks for information, Yea im just gonna get a lot of head work done. Do you remember how much it cost for the bigger valve conversion? If i may ask...
1989 Accord DX converted to EFI and OBD1 on P06 Ecu using Hondarulez RTP
Blaster 2 Coil, Pacesetter Headers, 4G Injectors, 4G Alternator, Skunk 2 B18 ITM, Skunk 2 68mm TB, Delta 272, Xenocron 255 FP, wire tuck, fuse box and battery relocation.
The custom valves I got were I think $33 each. For the labor to recut the seats and do a good 3 angle valve job, I would say in the range of $200-$300. Prices vary quite a bit from region to region, but you don't want skimp on quality here.
If you want to have them do any port work, DO NOT let them make the intake ports any bigger. They're already big enough and just need minor smoothing of any rough areas in the casting. At the most you can flare out the intake ports to match the intake manifold if you have to, but that's it. If you really want to get crazy you can smooth out the valve guides but will cost a fortune unless you go it yourself.
C|
Yea you told me 33 in another thread somewhere. Im not gonna skimp on quality for the valve work. I read that the seats are the most critical point of increasing flow and reducing reverse flow. :P
Yea I've read that when you get work done that you should be very specific about what you do and dont want them to do, and i'll probly tell them to call and ask before they do anything questionable. What about removing extra material in the port bowl? Any specific angles I should give them in the seats?
I was reading something somewhere and this guy said that the integra head uses 30, 45, 60 for the valve seats but the guy suggested that you can put a 90 on the side of the valve head...heres the whole paragraph on the subject...
He also said you should never lap the valves, that it makes the valve job pointless after so many miles. I dont remember exactly, something about wearing the angles down I think. Is this true? Should i tell them NOT to lap the valves?
Ports flow in both directions !!!
During overlap and at the point of intake valve closure the flow spikes back up the intake port. Now, since the reversion during overlap is basically inert you can't burn it again, and any time there's a large pressure spike (from valve closure), the mixture that was headed to the port via inertia is adversely effected to say the least.
My fix for this dilemma is the design of the intake valve seat. The configuration of the intake valve seat and the valve itself can minimize, if not stop the reverse flow problem.
A large intake valve or an intake port that flows great at mid to high lift, doesn' t have low lift flow worth a damned if I designed it. During my attempts to discourage reverse flow on the inlet, I found that any port that flows well at lower lifts will flow backward with even greater efficiency. So attention to seat configuration kills low lift flow, in order to discourage reverse flow. If I could design a port / seat configuration that would flow "0 cfm" at low lift I'd be happy.
The seat configuration that I use is only concentric on the angle that the valve actually seats on, and the top angle is the combustion chamber. Below the seat angle the inside diameter of the seat insert is not round and it is a continually changing radius in section view? No three or five angles here. The "seats from hell", as many customers call them, are configured in that manner to deal with the changing velocities and pressures encountered as the valve opens and closes. The seat is probably the single most important aspect in porting, as it's the transition from port to chamber / cylinder, and if you've done well to this point with mixture composition, this is where all your hard work up-stream will be for naught, if not properly done...
Regarding port size,...the entry and exit of ports have almost zero effect on port flow rates. The majority of the flow improvements are made in the short turn radius areas and the bowl's approach to the valve seats...
The best way to kill reversion on the intake valve is to simply put a 90 degree angle on the side of the valve head (flat with sharp edge margin to chamber side). We've never seen any worthwhile results from trenching the chamber side of the intake valve.
Valve shapes were the first place most of us began looking for reduction in reverse flow.
Intake valves like to have "square" edges...with the corner defining the break from the chamber side of the head to the margin being 90 degrees (or less) with a sharp edge (no radius) and the corner defining the break from the margin to the face angle being equally sharp.
If the seat is a pure radius, the valve would have to have a (matching) convex radius to seal with the seat, assuming there was to be more than (point) contact between the two components. The convex radius in the valve face wouldn't be conducive to efficient mixture flow. On the mechanical side....since the seat and the valve don't expand equally with temperature, the two designated radiuses wouldn't even match each other during thermal cycling. While simple stepped angle cuts do create some turbulence, they do provide a "simulated" radius of sorts and they also permit a positive seal with the face angle of the valve itself.
Exhaust valves like radiused corners for positive flow and reversion also likes the shapes. If we haven't stopped reversion prior to the valve, we will trench cut the valve, so there's a sharp step connecting the tulip (or filet) to the actual seated face of the valve. It's very effective.
Last edited by Susanoo; 07-05-2011 at 08:49 PM.
1989 Accord DX converted to EFI and OBD1 on P06 Ecu using Hondarulez RTP
Blaster 2 Coil, Pacesetter Headers, 4G Injectors, 4G Alternator, Skunk 2 B18 ITM, Skunk 2 68mm TB, Delta 272, Xenocron 255 FP, wire tuck, fuse box and battery relocation.
Find out what machinery they use for valve seat and valve head cutting, if it's Serdi you don't really need to touch the seats but I tend to use a t cut type polish or at most something a little more aggressive for scratches and then it's just a light twirl in both directions by hand no on a hand drill etc, just to seat them in a little.
The angles are fine, if you really want the best then I suggest finding somewhere that can do a 5 angle and radius the edges on the cuts, I also suggest that the seat width on intake is 1mm and exhaust 1.25mm on A20 head you can go 32mm on intake and 37mm on exhaust comfortably, you can go a little bigger by .5mm but you'll start running out of seat, on the A18 carb head they are slightly bigger on inlet and I've had 33mm valves on these heads and run a 38mm on exhaust side. This should be good for around 240-250bhp if i can get the compression high enough and the rotating mass decreased as much as possible, thinking about titanium ls eagle rods, titanium pins and custom forged pistons to my own spec. the stock items aren't bad though heaviest bit is the pistons which are stock cast and the wrist pins aren't particularily light although still lighter than stock as the centres are bored out more than Honda ones. The rods are stress relieved polished and balanced to the lightest rod from the set and the rod bolts are more than up to the job from honda as well.
Talk to SI valves about them if you can go with as narrower a stem as possible they do valve guides as well, if using A20 head you can't grind the valve guide bosses down on the intake side as they sit in a recess, what might be worth doing is JB weld filler to fill up the gap, and then have it ground down flush but i don't think you'll get a massive gain from this and then you'll have to worry about whether it will come unstuck from the head, i don't think it would as this stuff is crazy hard and sticky have some of it on side of a Weber 45 that developed a hairline crack and it saved the carb from being written off, it was too thin to be welded without warping it badly or making it worse.
If you really wanted the best of the best then you need to look at ET1 engine from Accord in Canada, these have much nicer flowing heads and the blocks can be bored out to same A20A3/4 spec but you need to make sure you can get hold of quite a few felpro head gaskets with the larger bore diameter for this block, it's not the same as A20, block came in late 2nd gen accords and early 2nd gen preludes mainly the carbed ones. Without the head gasket from Felpro this isn't possible to get the larger A20 pistons in without gasket issues or having a custom gasket made which all tend to be copper and leak oil and water badly(fine for race engine bad for road car).
Also you need to build the block right hand gap the rings using oversize ones, checking bearing clearances are spot on etc. etc. miticulous is the name of the game and if you get all these little things spot on and perfect you get a very good engine with less frictional losses and higher compression typically my new engine when run in pump out 215-225psi which is way more than typical new run in engine! (175psi honda qoute) and this can equate to 5-10bhp more on a stock engine.
The rest is all down to the quality of the headwork, the valve seat cuts, the valve head back cutting, your induction and exhaust setup.
150bhp is piece of cake, 180bhp bit or work, 200bhp needs good exhaust and extensive headwork, 230-250bhp requires best of everything and custom camshaft, valves, high compression, larger bore, lightweight bottom end but still is doable without spending a huge fortune.
Yea well for now, im gonna get it done stock so i can drive again and im gonna get another FI head to do performance stuff to, they wanna charge 247 to completely rebuild the head which I dont think is too bad...their sign even says "Aluminum Head Specialists". I forgot to ask what machines they use though, i'll ask when i take it down in a few minutes...Its close by too.
1989 Accord DX converted to EFI and OBD1 on P06 Ecu using Hondarulez RTP
Blaster 2 Coil, Pacesetter Headers, 4G Injectors, 4G Alternator, Skunk 2 B18 ITM, Skunk 2 68mm TB, Delta 272, Xenocron 255 FP, wire tuck, fuse box and battery relocation.
Even with a stock head you can do quite a few little diy things with a dremel yourself, and if you have access to a bench lathe too.
If not then having the race seats cut and stock valves back cut to match, the throats leading to the seats blended into the seats to remove any mis matching from seat to throat, and general clean up and smoothing off the port walls, all this will give you significant gains, I'd still recommend bronze guides they are cheap as chips from SI valves and don't cost much to fit.
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