A20 Engine Build Research for Rhonda And Shelly

[ShyBoyCA6]

Ok as some of you know i bought Monkey's Coupe Rhonda. Well the engine is giving up on me slowly so a rebuild will be coming down in a few months.I know that throwing a b16b or a b18c1 will be a good idea but i don't wanna drop in that motor in my cars. so i wanna build a perfect A20A3 motor and im willing to put the time and effort to keep the A series alive. A complete rebuild with a higher Compression with OBD1. so i been up late and been reading on pistons that might fit or not with a bit of work. i was wondering whats the highest compression anyone has done here. I read someone did K20 pistons but he has a turbo in his car i think. I was looking for at least 140hp or 150hp all motor which i doubt i wont reach it that much but would like to try to get close enough. i know some of guys here have done alot of work and maybe thought you guys can throw some ideas. for sure ill be getting a Level 2 cam or the ones that get alot of good feedback. I hope i can get some really good info. Thanks for any Info!

[cygnus x-1]

so i wanna build a perfect A20A3 motor and im willing to put the time and effort to keep the A series alive. A complete rebuild with a higher Compression with OBD1. so i been up late and been reading on pistons that might fit or not with a bit of work. i was wondering whats the highest compression anyone has done here.

The highest compression that I know of was the engine originally put together by Openloop, which was then sold to MessyHonda, and then I believe Hondalude86. That engine had welded up combustion chambers and the compression was somewhere around 10.5:1 (guestimate). I don't know if it was ever actually measured for real but I think it was in the 10 range.

I have long range plans to build up a killer A20 head with bigger valves and compression in the mid 10s as well. I'll be milling the head though instead of welding. I've done some test cuts on a scrap head and I figure I can take off 2mm without compromising the head integrity. No idea when it will be finished though.

To get any higher compression than mid 10s you would need to get custom pistons or do some serious welding and milling on the head. You could go as high as you want if you have the money to throw at it.

I read someone did K20 pistons but he has a turbo in his car i think.

Never hear of using K pistons. There are some B pistons that fit though. You can probably find more info if you search around on the old threads. But you can also just have some custom pistons made. It's expensive, but relatively speaking it's actually not. Figure roughly $600 for set of 4 custom forged pistons. Many of the major piston companies will do this, Diamond, JE, Wiseco, etc.

I was looking for at least 140hp or 150hp all motor which i doubt i wont reach it that much but would like to try to get close enough. i know some of guys here have done alot of work and maybe thought you guys can throw some ideas. for sure ill be getting a Level 2 cam or the ones that get alot of good feedback. I hope i can get some really good info. Thanks for any Info!

Those numbers are definitely achievable without turbo. Get the compression up to around 10 or so, do some mild head work, stage 2 cam, B16 or similar intake manifold, some sort of header, cold air intake, and a good tune and you should be set.


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[ShyBoyCA6]

The highest compression that I know of was the engine originally put together by Openloop, which was then sold to MessyHonda, and then I believe Hondalude86. That engine had welded up combustion chambers and the compression was somewhere around 10.5:1 (guestimate). I don't know if it was ever actually measured for real but I think it was in the 10 range.

I have long range plans to build up a killer A20 head with bigger valves and compression in the mid 10s as well. I'll be milling the head though instead of welding. I've done some test cuts on a scrap head and I figure I can take off 2mm without compromising the head integrity. No idea when it will be finished though.

To get any higher compression than mid 10s you would need to get custom pistons or do some serious welding and milling on the head. You could go as high as you want if you have the money to throw at it.




Never hear of using K pistons. There are some B pistons that fit though. You can probably find more info if you search around on the old threads. But you can also just have some custom pistons made. It's expensive, but relatively speaking it's actually not. Figure roughly $600 for set of 4 custom forged pistons. Many of the major piston companies will do this, Diamond, JE, Wiseco, etc.




Those numbers are definitely achievable without turbo. Get the compression up to around 10 or so, do some mild head work, stage 2 cam, B16 or similar intake manifold, some sort of header, cold air intake, and a good tune and you should be set.


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Thanks Cygnus you been a great help. ill read up on openloops threads and see if i can come up with my own set up instead of copying it to be the same. also i want my motor to be 10.5:1 and not any higher as it might be a hassle if something snaps and causes internal damage.

A friend of mine mentioned Dome Pistons to bring up compression? im not sure if hes right on that but you said that i can order custom pistons from the names you listed. so with mild head work i would need bigger valves? and springs? i dont wanna be asking to many questions or make it seem im being spoon fed with answers. i will be doing the work on the black coupe first since its non operational right now and still under construction for the build. well time to hit the search and start reading some more. thanks again

[rjudgey]

Headwork is the key and having a high flowing induction and exhaust header/system.
The block should be hand rebuilt use of 83mm A20A3/4 pistons with 9.4:1 CR ratio as stock combined with a bit off the top of the block .5mm, and 1-1.5mm off the head will get you easily up into the 10.5:1 area possibly bit more, if you wanted to go higher i would recommend custom pistons from diamond using a flat top with just 3 valve relief pockets on each this should get you upto 11:1 area. The block should be blueprinted and oversized rings used and gapped by hand perfectly. You should be able to get a nice high compression from these engines i get typically around 215-225psi from a newly built run in block.
Head should have nice race style valve seats make sure the machinist has Serdi cutting kit or walk away to someone who does, bronze guides a must with aftermarket cams or the stock ones wear out really quickly! port work around the guide and the throat where they meet the seats essential. 1mm seats is key and the valves should be backcut to match the seat widths, a 3 angle with radiused edges is good or a 5 angle is even better but not many shops have the tools for this.
Valve size increase is a must and if you can having smaller stems on all the valves is better but not hugely critical better to have larger valves then just smaller stems or if cost for having the guides made for smaller stems is more and having to switch to new collets and retainers is too much money then stock stem sizes isn't an issue I have 7mm stems all round which is huge compared to most modern engines! but at least they won't be snapping!! lol!!
Camshaft wise if you want something that idles reasonable and gives good all round power then a camshaft off around 260-270 degrees and 10.5-11mm lift is the best 285 degrees and more idle is out the window and so is much of the power below 4k rpm but when you hit 4k rpm it runs like a bat ouf off hell to 8-9k rpm depending on how the engine is built and head is modified.

150bhp is really is to get, 180bhp bit of work 200bhp with some nice bits and bit of money 230-250bhp with a lot of hard work and perfection in headwork and block prep and some nice lightweight titanium parts but not as expensive as you would think!

[gfrg88]

take a look at at hondalude86's build thread, he's doing a nice n/a build

[rjudgey]

Ryans build is a bit over kill for 140-150bhp lol! His engine should be well capable off 200+bhp if his exhaust manifold and system is big enough.

[ShyBoyCA6]

Thanks Rjudgey im beginning to get an idea of what i should look for and precise information! Know to only find a shop that does great work with a lot of feedback i hardly trust anyone when it comes to my stuff and money. ill take a look at the guys build and see what i can get from his or try to go a different way.

Im learning alot for only being here almost 3 years. at first i wanted to take the easy way out but im not that type a guy. so a "Perfect" A20 is gonna be my goal till i find a way to boost it or just go N/A all motor. Thanks for the Help!

[rjudgey]

Well theres a nice set of A20A3/4 83mm bore pistons with rings and pins for $87 on the below thread in this section I've ordered 3 sets for spares today.
Start with those rebuilding the block with a rebore, personally I'd opt for some larger rings and hand gap them to the new bore size. ACL race bearings for the crank and rods, have the rods polished/stress relieved, shot peened, balanced, stock bolts are fine, pistons balanced and then have the pins and pistons fitted when all the balancing is complete. If the crank is not damaged and journals are nice and shiny just leave it as is, I've not come across one that has been out of balance yet but might be worth you getting it checked and done if your worried about it. Make sure you get the block cleaned up as well and then you can start assembling this together with a nice new oil pump Toga one is good, and water pump one with cast impeller is the best design. Hopefully you have the A20 with a windage tray most late model ones do, then look around for an oil cooling kit you can rig up onto the oil filter plate. Make sure you have the block decked though to make sure it's flat also helps compression too .5mm is good for a nice bump.
Felpro Head gasket kit worth investing in make sure the head gasket itself is the racing blue one as these are the best we can get for High CR and general race use. Then thats your block sorted next up is the head.

Machine shops are hard to find that are reliable, hopefully your ok main reason why i got into building my own engines is because of unreliable engine builders and dodgy machinists.

[rjudgey]

OK so now onto the head.

Is this going to be a budget build or do we have enough money for bigger valves?
Bigger valves will easily give you more power and torque over stock ones, stock manifold can easily support 140-150bhp if not more.
If sticking with stock setup style injection I would go down this route.
Bigger valves, race style valve seat cuts 1mm seat widths on intake 1.25mm exhaust have the valves backcut to match the seat widths (on stock valves too).
Bronze SI valve guides all round (really cheap upgrade)
Reshape the exhaust port and guide boss end.
Blend intake throats into the intake valve seats
Clean up intake port walls and leave a nice matt to rough finish with flap wheel
Clean up exhaust port walls and leave a nice smooth polished surface
Clean up combustion chamber deshrouding around the valves as much as possible and smoothing out and blending in any machined edges, smoothing off the edge around the chamber to stop pre detonation.
Skim the surface to bump up compression 1.5mm is fine and leaves a bit of meat left for future refurb.
Total off 2mm from head and block should give a nice bump in CR ratio combined with the 83mm A20A3/4 pistons should get you around 10.5:1 maybe a bit more.
Then look at a Bisi or Web cams camshaft with extra lift rather than duration, finish off with a tubular header preferably have the collector modded to have a 2.25" main pipe and have a 2.25" system mandrel bent put on with 2 sports silencers.
Intake wise if you can have the manifold runners polished up, throttle body can be knife edged on the mouth, counter sunk screws into the butterfly, if you can have it professionally bored out and bigger butterfly put in, set of matched slightly larger flowing injectors, an adjustable pressure regulator, and maybe F22 Map sensor, Cold air intake with nice big tubing and filter and if you have the time and electrical skills going for a megasquirt setup is usefull and will gain more power and better economy.
Setup like this should easily get you around 145-155bhp maybe more depends if you run a sports cat or no cat depending on your regulations.

[gfrg88]

Didn't read lol.. If that's all he wants, I'd look into some b18 rods, ttr pistons, some nice work on head/cam, itr IM/TB, and tune

[rjudgey]

Think the rods and pistons would be overkill and they'll weigh more than the stock items stock rods very light and pistons aren't too bad if combined with some lightened pins.
I use stock pistons and rods and light pins and have had no issues at 200bhp and 8000rpm spin speed.

[MessyHonda]

its going to take more money to make power in a A than a B

come join the B side

[rjudgey]

Think I'll take a 200bhp A any day the extra torque over B16/18 is pretty considerable! Although a B20A could be pretty interesting with some Webers hope to find out just what can be done in the next few months!

[ShyBoyCA6]

its going to take more money to make power in a A than a B

come join the B side

ill join in time when my A20 decide to let me down then ill join the b side.

[MessyHonda]

ill join in time when my A20 decide to let me down then ill join the b side.

[lupen]

My 88 Accord is stock, with carb. I ported the heads and cut the valves. Once that was done I put larger dia. exhaust on. This improved the get up go plus top end on the accord. I have had mine up to 250kph without any other mods. Well had to put a wing on the back, to keep it down forced.

[Rendon LX-i]

Better make the obd1 dizzy modded to fit a a series head to use. (who said a adapter plate was needed) lol looks clean to huh

[gfrg88]

Don't forget that wing for all that crazy power you'll be making!!!!!!

[rjudgey]

Lol not felt the need to use one on my lude just yet felt fine at 150 which is surprising given how light the car is in the back!

[cygnus x-1]

Better make the obd1 dizzy modded to fit a a series head to use. (who said a adapter plate was needed) lol looks clean to huh

Is there a picture of this mod somewhere? I'm curious to see what it looks like.


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[gfrg88]

He's talking about cutting the tabs off and rewelding..

[Rendon LX-i]

Nope no cutting or welding. Just grinding an drilling an smoothly things out .

[Rendon LX-i]

The dizzy is sold but it's a f22 of course just some grinding an drilling an wala. Bolts right up .

https://www.3geez.com/forum/showpost....&postcount=680

[gfrg88]

Sorry, bro. But that shit is FAR from clean!!!

[89T]

True.

Josh send that dizzy to me, and I will clean it up. If you remember I was in a huge rush to get it to you.