Hey, I was just curious what you guys thought about piston size. Do you think that I should get the factory bore, or should I go up to 82mm pistons. I know that the larger bore will increase power, but by how much? Is it actually worth taking the block out and having someone overbore it?

 

81.5 mm

 

Are you considering taking the engine out of your car just to put pistons in?

 

Well, I already have the type 3 cams, so now I am getting the JUN pistons (12.3:1) and I am thinking of getting their rods also. The head is also going to have some work done, but back to the original question. Does anyone think that it is worth the money of a machine shop to bore out the cylinders even thought the cylinder walls are perfectly fine.

 

The Type R cylinder walls have a Nickasil (sp?) liners. I'm not sure of the thickness though - you may compromise the strength of the cylinder walls by overboring too much and might be better off re-sleeving the block. IMHO 82 mm should be fine.

In answer to your question - if you are changing cylinders you should have the block at least reworked or else your new rings might not seat properly.

I just had my block overbored to 81.5mm (Endyn RW) and it's fine.


[Modified by Big Phat R, 3:15 PM 8/1/2001]

 

How do you like the Jun stage 3 cams? Is that your daily driver?

 

I love the JUN Cams. They made the car a lot faster. It is also my daily driver. It runs just like when I bought it except with a lot more power.

 

I just wanted to post one more thing. Do think that with the 82mm pistons that there will be a noticable power difference from the 81mm pistons?

Big Phat R-How is your new bottom end, how do you like the endyn pistons? Is it a lot faster??

 

I thought the only reason you would want to bore out the cylinder walls if it's not for increasing displacement is because you have damage to their surface. If you bore it out, you are essentially shortening the life of the cylinders because you will have less room to smooth things out should they get damaged in the future. I would think it better to just hone them if there is no damage and save the extra headroom for when you really need it.

 

John when are you getting these?

 

regarding sleeves and bigger bore:
http://ferrari.colowatch.com/php/sho...=0&part=3&vc=1

nice....GE sleeves support the cylinder midway where the sideloading is the greatest rather than at the top which is where the hype centers aroung the blockguards claiming this is the weakest point. The "posting" of cylinder wall supports midway ensures allowanc for coolant flow to the top of the block and back to the rad and therefore prevents overheating associated with blockguards.

82.5 mm bore nets you 1.9L with the 87.2 mm stroke. It's easier to get bigger displacement by boring out than by stroking. If you do the math a 1.5 mm increase in bore will give a larger incremental displacement increase than by elongating the stroke by 1.5 mm.

Increased piston surface area by boring out will net you more power and by unshrouding the valves your engine will breathe better. How much? it really depends on your tuning experience, how efficiently your flow through the head is for that displacement, and how efficiently your setup can burn the air fuel mix. Jarrod Silver's old bored 1.9L B18C1 powered CRX ran 11's and was daily driven...so that can be a max indicator of potential with an increased bore. Your package dictates how much.

The down side to a larger bore is that the flame must travel a longer distance in a short time with the lower rod ratio of the ITR and so a complete burn will require even more spark advance. The bigger bores do not ignite as evenly as smaller ones with compact combustion chambers. The sideloading on the pistons is larger with the distance from bore to piston pin is larger. The larger bore causes a longer flip-flop transition at TDC from the piston travelling up stopping and then starting back down: so more piston to head clearance is needed, You will need a specialty head gasket , spot facing the quench areas to the bore size , and opening the sides of the chamber to the bore size , as you exceed 82mm.

cheers

 

First question is Who told you the comp. is 12.3? Second question did you know that by overboreing you're also dropping the compression level? Now that's on a stock piston that is just bigger. Also the shorter skirts on the JUN pistons might make the piston not last as long.

 

JUN told me that it was 12.3:1. I don't know much about pistons, but why would shorter skirts not make the pistons last as long

 

Derrrrrrrrr, were you at the ITR expo. uh yeah we were the Guy's there with JUN um hum, that is probably how we know the actual comp. ratio on a 1.8 is 12.3:1 although Johnathon I dont think we were supposed to tell everyone

 

The motor that was in the white Type-R is a stroked B16A and the compression on that is 12.3. (Maybe) I know for a fact unless that they just started making these compression pistons that they only sell 11.5:1 pistons for B16 and B18..............

 

That is what they tell JOO mang

 

No I used to work for those guys!!!!! And I also know Paul Subramanya !!!!!!!!!!

 

Can any of you please tell me the duration of the Jun 3 cam's VTEC lobe at 1mm valve lift?

The shorter skirt problem is seen in the Arias pistons which rock as they travel up the stroke. I believe OEM Honda skirts are onger and are coated.

 

Whoopedy doo, I have met paul, I know Don, I know Mark and it doesnt matter. I am going on what they told me when I was in there shop getting a car ready for the ITR expo, They told about 6 of us that, now if they were mistaken than so be it. The fact remain's that is what they told us.

 

All else equal, overbore will INCREASE CR!!Think about the top of compression chamber remaining fixed in volume but now greater volume being pushed by piston...

 

Here I am in the big 2026 reading this before buying a B16A type R block I found for cheap that recently had been worked thru. This definitely helped me understand what it needed when over boring to 82.5mm. I have an EM1 I want to show some love to and put a fun motor into it. So slowly ima build a type R motor for it. Thanks a lot. Keeping the Honda scene alive in Modesto Ca 🤟🏽