Hi guys, i'm going to rebuild the motor and to get higher compression ratio as well. Need little help finding information about combustion chamber volume, bore, stroke, the exact compression ratio of 88-89 A20. Thanx :pimp:
Diamond Pistons Specs
Hi guys, i'm going to rebuild the motor and to get higher compression ratio as well. Need little help finding information about combustion chamber volume, bore, stroke, the exact compression ratio of 88-89 A20. Thanx :pimp:
The A20A3 bore=3.26 in. or 82.7 mm stroke=3.58 in. or 91mm 9.3:1 comp ratio for the 88-89. Do not know the combustion camber volume sorry.
87 4dr LX "It was FREE"
91 CRX Si it was only $500 hehe
Check out this board
http://wsbf.net/phpBB/viewforum.php?f=28
There are guys there with ludes over the 200hp mark. That board has all the hard core 2g prelude guys. There is not a question that they don't know the answer to.
Also have you been to preludepower.com???
I ain't no junky...... I just keep it funky
-Weber DCOE's
-Colt Cams Stage II Triflow
-Headers
*What is the exact bore the Diamond pistons require? (Prefer smallest possible bore for maximum sylinder wall rigidity)
*What piston-cylinder wall clearance?
*Are they low- or high-silicon? (Low silicon= bigger clearances - expands more - takes more of a beating. High silicon= smaller clearances - expands less - takes less of a beating.)
*Asking about the 9.2-9.4 compression (whatever is easier to get) pistons with the 21mm wristpin for a FI buildup.
*What do they cost incl. wristpin and rings? I will preferably buy these from Sean to show my appreciation for all his efforts.
I want a piston that gives about 9.2-9.4 compression in my A20A4, and that will withstand 400 WHP @ nothing more than 7000 RPM. Also, they have to have the 21mm wristpins for use with the Eagle H-beam connecting rods.
So what clearances to they require? Also, low or high silicon content?
shepherd79: This engine will be built as a low-RPM torque monster, and that's why lower compression is out of the question. I will run a good intercooler, water injection, 10% toulene in the gastank, Haltech E6X direct fire /w 4 coils for DIS, J&S Safeguard /w knock sensor(s) and a TechEdge WBO2, so detonation and/or preignition is not something I will be all that worried about.
I realize that my A20A4 has a bore*stroke of 82.7mm*91mm, I was just wondering if Diamond builds clearances into the pistons so I'll know if I have to bore it to 83mm or like 83.1mm. Guess I have to email them, and ask them directly.
I would not overbore an (ANY!) engine for the sake of more displacement, I'd overbore it to get the old wear marks away and the new pistons in. More displacement is always the cowards way out, real men just up the boost, or even better; combine it with DIY-racefuel and/or other manly tricks.
Now I'm wondering about if, and how deep the wear-marks are; if possible I'd get a custom bore piston to use with a 82.8 mm bore. Guess I'll have to ask my machinist about the cyl-walls conditions @ 82.8 mm. Diamond _can_ make a custom bore piston, right?
The bottom-line moral of the day is: "Don't bore a FI-engine any more than what is absolutely neccesary (sp?)".
yea that sounds about right. Sometime I need to go and get my self a barrel of it for experiment. oh yea the bore is 82.7mm and stroke is 91mm.
Last edited by Justin86; 07-30-2004 at 05:06 PM.
I'm your local R&D nut. Fabracting, welding, tuning and breaking my stuff so you don't have to.
The max overbore is about 83.01 mm - 83.02 mm. So forget about the 83.1.mm its just too much. Besides, if ur gonna go boost, dont over over. If ur gonna go na, then u might but its not worth ur money i tell you. That extra 0.1L of displacement is not gonna give u much.Originally Posted by Oyvind Ryeng
the service limit is 82.73mm which is 0.03mm over the stock. So u will be good. ur not gonna be cutting any deep gash into the engine or the wear is gonna be that bad. Its a cast iron engine my man. Besides, thats why u have the piston rings to contact the walls. Besides, if u think that ur motor car wear 0.1mm, then u need to take a closer look at what "tolerance" actually means. Hope that helps.
Yes. Talk to Ron Beaubien.
[email protected]
Contact Ron Beaubien at Diamond ([email protected]) and tell him you want pistons like they made for job # 18604. Be sure to specify what compression ratio you want though.
They are 20mm.
"Feed their greed with your need for speed"
yeah but going to maximum overbore somtimes invites cracks between the cyls... just get it honed to what you need... dont have bore it to have a nice ring seal
429whp 362wtq A20 TURBO. A20T>*
you can get a few nice bits from K-mod racing, but you guy's you can't just drop forged pistons into standard bore block, the cylinder bore clearance on forged pistons is bigger than cast as forged ally expands more, you have to have the bores bored out slightly to allow for the expansion, p.s 83mm is probably the maximum safe size to have for FI and 83.5mm for N/A you can get 83.75 but your right on the limit then!! The extra increase in size is not going to make any real power difference just stick to stock size unless bores are worn or damaged or if you are fitting forged pistons.
they come with everything. all the rings and the wrist pins. i believe the wrist pins are 21mm..., so i don't think they'll fit the stock rods cuz i think stock is 19mm... i actually didn't even realize this till i was looking at everything just now. anyways, here's some links to pics, they're 1024x768, so kinda big. anyways:
http://www.maka-rth.com/pics/jepistonsbox.jpg
http://www.maka-rth.com/pics/jepistonsspecs.jpg
http://www.maka-rth.com/pics/jepisto...everything.jpg
http://www.maka-rth.com/pics/jepiston.jpg
i'm thinking $300 shipped ground and insured.
*edit: if you're looking to get new rods, you may as well go with some aftermarket ones that are 21mm anyways instead of the stock rods. i now both eagle and scat will make rods you could use. don't know part numbers for those tho...
Last edited by maka_RTH; 09-17-2004 at 12:17 AM.
Greg
1989 LX-i 2dr 5spd (R.I.P.)
2008 CBR 600RR -- 1995 Toyota Supra NA -- 2013 Nissan Frontier Pro-4x
stockers are 20mm.
87 prelude si
87 non-turbo supra
I have done extensive research on this board and everything i have read and re-read say's that stockers are 19mm...
thanks to mr. maka_RTH i now have new pistons and ordered eagle 'h' beams with 21mm wrist pins.....
look look into the light a high compression boosted 3g ............
what was i thinkin!
oh i think it's going to work..
i am just trying to be funny.
i am going to give it a go though..
i did order a bunch of goodies...
i ordered a turbonetics wastegate, blow off valve, fmic, je pistons (thanks greg), eagle rods, safc, msd fuel press. reg(boost dependant), msd btm, aspec 3" to 4.5" muffler
and a 255 lph fuel pump.......auh! i got it out in one breath...lol...
still thinking about the injectors, and whitch turbo to use..
any suggestions?
i am trying to keep it street leagle also...
by the way out of everyone i have delt with money wise on the net greg was the best...
mad props to greg!
that was the thought....high compression low boost..
say you had a engine that had 8.5:1 comp. and runs 14psi of boost making say 250 hp. actual compression will be about 22:1 under boost..
now the same engine with 10:1 comp. running 9psi making the same 250 hp.with the same actual 22:1 comp. under boost...
you make the compressor more efficiant...not to mention the extra tourque when not under boost...
(those numbers are hypothetical)
to me this makes sense but if you have a diffrent opinion i want to hear it...
and if i have to i do have a standalone.. i want to see what the limmit on the stock is..
now the copper: http://www.importperformanceparts.net/
$88 to $120 from .031 to .125
copper gaskets are stackable...
on the other car i boosted i pulled 108.9hp per liter (2.3l)
that probably dont sound like much but when the stock hp is only 88 you'll see the big picture..
I have a slightly different opinion. Where do you get your numbers?? Atmosperic press is 14.7psi at sea level. Take a hypothetical engine with 8.5:1 dynamic compression, assuming 100% VE, running no boost at sea level. Running another 14.7 pounds will theoretically give you a "dynamic" compression of 17:1, assuming a doubling of your VE. Where do you come up with 22:1? And my way of looking at it doesn't exactly correspond with reality either, as the air is already partially compressed as it enters the cylinders..
Think about this scenario: 2 engines, one N/A with a displacement of 4 litres, and another boosted one bar with a displacement of 2 litres. Both engines have the same compressed chamber volume, in other words, the same static compression ratio. So both engines are taking approx the same amount of air and compressing it into the same volume, just 2 different ways. However, if the charge air is at the same temp as the N/A engine's intake air, the forced induction engine does not actually have the equivalent of double the N/A engines dynamic compression, (at least in one way of looking at it) because part of the heat of compression was taken out by the intercooler.
Intercooling has the ability then to increase the total VE of an engine, but damn, then are you looing at the dynamic compression as a function of mass vs compressed chamber volume..instead of initial volume vs compressed volume..whoa ok never mind I am making myself dizzy. What I am really trying to say is that shit is too complex, there are too many variables that go into to just look at it in those terms. I agree in general that a higher static CR engine will give you better response, and have a lower bsfc, but you probably still could run like 20psi with 10:1 if you have good enough intercooling and run rich enough, and take out enough timing. If you want to read some interesting articles about this shit, I know a good site, endynracingengines.com. L. W. runs 27lbs on his raised deck destroked d16z6 with 11.2:1 static compression. 1.55L, almost 500hp.
like i said those numbers are hypothetical....
here is a good site for you... http://www.turbofast.com.au/TFcompB.html or http://www.turbofast.com.au/javacalc.html
the #'s werent quite as dramatic as i posted....
I wasn't trying to do a write up or anything...
I was looking at a honda builders hand book by cartec they did a comparison on a civic...
8.5 vs 10.5...the 10.5 had better #'s on hp and tq..the only real differance was in cfm...the 8.5 had a slite advantage.
all i was saying was you can possibly make a turbo set up more efficant.
that was the thought....high compression low boost..
say you had a engine that had 8.5:1 comp. and runs 14psi of boost making say 250 hp. actual compression will be about 22:1 under boost..
now the same engine with 10:1 comp. running 9psi making the same 250 hp.with the same actual 22:1 comp. under boost...
you make the compressor more efficiant...not to mention the extra tourque when not under boost...
(those numbers are hypothetical)
to me this makes sense but if you have a diffrent opinion i want to hear it.....
more compression doesn't get more oxygen in the engine to be burnt, more boost does. this is the big difference....now which provides more power? more O2 or less O2, but more highly charged ie. compressed more? As far as more torque off boost, just make sure you stay on boost
i agree, but when you are running a t3/t4 hybrid 62-1 with a stage 3 turbine it is a little harder to spool..especially when you don't belive in nitrous, and still running and automatic.
the car is alittle slow off the line but when she comes under boost she pulls pretty hard.(i also have a full interior and a big ass box with 4 orion 10's)
Thats why the high comp. pistons..
i am still playing with the fuel so i can run more than 10 psi.
What rods are you running?
eagle H-beams
So for rods all i would need to do is get a set of eagles or which ever brand i choose for a teg ls and get the small end milled to 21 millimeter. And then when i order the pistons say which compression i want, bore, and wrist pin size. I am hoping to get this done soon i have another motor that i would like to build.
86 Accord LXI HB
Pacesetter Header, Gutted Cat, Monza Exhaust 2.25", Bosch Plug Wires, Msd Blaster 2 Coil, NGK Plugs, Custom Cold Air, Centerforce Stage 1 Clutch, Fel Pro Head Gasket, Rebuilt Head, Integra Tranny Conversion, Delta 282 .430" Cam Grind
Has the price changed at all? Wiseco quoted me 780 cdn
I got mine 2 months ago and they cost me about 380 bucks. The work is real nice and clean. Ron at Diamondracing is a good guy to work with when tring to figure out what you want.
what was the turnaround time for you getting your pistons? i may be in the market!
Does anyone know the part numbers for these or even if it ever happened... Get back i'm in need of forged pistons...
call them up and tell them chris and elijah just ordered pistons within the last couple months.... they DO still make them, but they are custom, but call them up www.diamondracing.net and ask for eric or ron tey are super nice guys.
btw these are not cheap! i paid over 600 for my piston/ring setup
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