Piston/rod questions

Ok, I want to increase the output of my B20b and I see there are many places that have pistons and rods of various lengths and sizes all supposedly for the b20b. I'm pretty sure that you want a Rod to stroke ratio of ~1.7??? I know that the stock configuration has ~1.54 (at least I think). I was wondering if it would be possible to get a different rod length and a piston made for that rod length and just change the r/s ratio, or if that was a no-no becuase it wouldn't fit or something. I figure If im going to be spending 7 or $800 I might as well get the best I can. I was looking at the eagle rods and the SRP pistons, at about a 9-10 CPR (I didn't want to go to high, beucase I dont want problems and I might want to super or turbo it later) the longer rods (5.531 vs 5.394) give a better r/s of ~1.58. Basically I was looking for some advice on some of this stuff, like if you can mix and match pistons and rods, and pros/cons on dome and and dish pistons, and basically whatever I'd need to know to order a set of pistons and rods for my car. Even if you can point me to the direction of a website or a fourm that address's all this, thatd be cool too.

A more specific question (after some looking), would be this:

Str Rod Type Man. CR(41.6,42.7) Dish
3.504 5.394 Dish JE 9.4 9.3 -11.9cc
3.504 5.531 Dish SRP 8.5 8.74 -18.0cc

The first of the 2 was what I would have originally thought to be better for me, but if I were to get the second of the 2, at an 8.5 CR, and then get a rod of length, say 5.862 or 5.967 instead; that would increase the compression and the r/s ratio right? So would that be a better option, or is my theory wrong, I know Id have to get some actual numbers before I bought them both, but I was just wondering...

BTW: Are the brands im looking at good, or are there some other good ones that I should be looking at?

Thanks in advance,
Buzz1167
Jon N

for your question about pistons and rod length
If you are going to increase rod length you may need to get custom rods made. Eagle does custom rods but it's costly. They want to know center to center length, big end bore, pin bore, style, and material. The SRP brand is one of the best for forged piston. If you are increasing rod length with rods that already exist you need to watch for deck clearances. if you buy the rods and use the stock piston to measure you can see if you need to have custom pistons made. The problem with increasing rod length is that the pistons on high compression motors like hondas already create a small deck clearance. If the stock piston stick out of the cylinders the new pistons have to have the pin bore centerline to the head of the piston reduced via a special aftermarket piston or a custom. SRP will make cuostoms. A dome is usually not a good idea for airflow and combustion, flat tops are usually the best to keep the designed air turbulance to the desired amount. Dished pistons are good if you plan to supercharge or turbo to decrease the compression. I'd say if you plan on going high boost, i'd go with the lower compression available. The other problem is the cam, if you are changing to supercharged or turbo you need to know your exact compression. You need to call a pro cam grinder or manufacturer with the spec's of your motor to get the correct cam duration to keep your effective compression well below your dinamic compression

Thanks, the reason I asked is beucase they have stroker kits with pistons of various sizes and rods too. So I thought maybe I could buy a long rod with a "short" piston (low compression) and keep a decent r/s ratio and compression. But I guess the compression doesn't completely rely on the height of the piston, thats what the dish and the dome do eh?

So I guess what im really looking for is how to tell how tall the entire assembly is going to be (call this deck height?), do you just call up the manufacturers and ask them, or is there a better way to do it?

I notice that the eagle rods are about 370-400$ and the JE or SRP pistons are about 400-450$, Are these decent prices or am I getting jacked? Oh and whats your rating of the JE pistons? How much would you think a set of custom pistons (by anyone) would put me back?

I would just buy the rods and check like you say, but I have to use my car also. I mean I can borrow a ride but I'm really wanting to do this all at once over a holiday weekend or something. By you giving that comparison though, it makes me think that all the pistons for a certain engine area all the same height from the rod end, is this true?

BTW: if Im going to be ripping the entire engine out, is there anything else I should be looking at? Maybe the main crank bearings, or some cheap upgrades that I might need in the future that would also require the engine totally apart. (I plan on doing a crvtec conversion later).

Thanks,
Buzz1167
Jon N

I'd say if you are going this far i'd go to a pick and pull or something and find myself a good core, or something you can tear apart in your garage while you are still driving your car. Then have it honed out and build the bottom end. new main and rod bearing (a few hundred) and have the crank polished (less than a hundred) install the new rods and pistons and find out what you need. Then when you are ready all you need to do is change over the pan, oil pump, water pump, pulleys, head, and timing belt. I'd say install a new cam pulley system for cam timing adjustment. Or see if you can find someone on Ebay or somewhere willing to sell just a short block. New rings would be needed for a honed block, but i'd change the rings anyway. The waterpump should be new aswell, plus the timing belt. cause while it's apart might as well do some preventative maintanance. Oil pump if you are really into it. Switch to syntetic for a bit more power. Post the engine type and i'll see what i can find for added power cheap.

Its a b20b, from the 1997 crv. Im going for the pistons and the rods. Thanks for the ideas, I know a better water pump would cool it down some, and I used mobil one synthetic for the last few years, I wans't sure if you meant the type of oil, or if syntetic was a pump brand. I kind of placed pistons rings on the discretionary list, figured if I was replacing pistons, I'd need rings too. I hadn't thougth about getting the crank polished though, what does polishing the crank do to help the power? I thougtha bout new bearings, but I'm not sure who makes them, or what are good bearings and @ what price. Unfortunatly my budget is not unlimited. I know of a ceramic bearing place called boca bearings thats supposed to be good, but I dont know the difference between "regular" bearings and engine bearings, nor do I know the size for a quote, in fact I dont even for sure know how many, I assume 5 (3 in the middle and 1 on each end)?
I also plan to do a b16 head swap after I do all this upgrading, and a turbo after that. (thats a year down the road though) I just wanted to make sure that anything I buy now will last though the upgrades, like the compression wont be all screwed up when I switch heads will it?
And a final question (hopefully) about pistons. I know that they have reliefs for the valves, but do they all have big enough reliefs for the vtec conversion, or are there special pistons for that, that I should be looking at (so I dont have to change)?
Also poncho, thx for the ideas, and could you suggest maybe some websites or manufacturers that I can look up for the pumps and bearings? And thx for the heads up, but If I go a day or so over the holiday weekend project (as I assume I will, becuase thework is adding up :smile: ) I can borrow a car if I had to, My mother has 2 cars. I figure what I would do with the head, is keep it stock, for now, and when I get the b16 head I can bother with buying a new timing belt, and stuff for the head. The timing belt on my car will probably be due for a service about next year anyway. :naughty:

Thanks,
Buzz1167
Jon N

Polishing the crank is just good for life of the engine. Plus it opens up the clearences by a thousandths of an inch which can increase the life of the engine. Clevit 77 makes great performance crank and rod bearings. For a V8 bearings usually run about $120 and the main bearings come in sets. As for the piston clearance, install the heads with about 1/8 to 1/16 inch of clay (keep it thin) on the piston, install the intake cam, (install only one piston for this) make sure the valves are not open then rotate the crank slowly, you'll feel the interferance. If it gets to hard to rotate then stop, there is massive interferance, otherwise when you pull the head you'll see any indents in the clay, that will show you how much clearance you have. You need to find the combustion chamber volume for the cylinder heads if they are the same then you don't need to worry about compression change.