Bore and Stroke (B18B1)

[M@St3R_D]

Ok... I'm about to start a Turbo LS/Non-Vtec project... I'm looking for a 350-400HP streetable car. I'm gathering infos because I wanna build my engine from A to Z and I don't have no worries about money... So here are the first things I'd like you to help me with...

Stroke:
I know that the R/S of a B18B1 is 1.54 and that the ideal R/S is 1.75... To get close to this ideal number, I need to decrease the stroke (which is originaly to 89mm) right??? I think that 77mm of stroke would be close enough giving 1.74 R/S... Correct me if i'm wrong... Diminishing rod lenght (which is originaly 137mm) would help achieving this goal... If I missed anything from now on, just let me know... Is it possible to do so w/o diminishing reliability??? If yes, experienced suggestions would be appreciated... Regarding to my knowledge, this is a good modification for FI application on B18B1 because horizontal pressure on cylinder walls is diminished...

Bore:
Also, I'd like to increase the displacement of my 1.8L B18B1 (1834cc) by reaching 2.0L... To do so, I would need to resleeve the cylinders to 84mm right??? I heard good things about the AEBS T-sleeves... Would it be a good idea to do so??? Would it be reasonably reliable??? Again, if I missed anything, just let me know... I don't push the car to maximum all the time so... That can give you an average idea of the engine use...

I got most of my informations by searching this forums "R/S, Bore, Stroke...". Thanks a lot for your great support guys

[spooleffect]

Originally Posted by M@St3R_D

... Diminishing rod lenght (which is originaly 137mm) would help achieving this goal...

That decreases your rod ratio.

[M@St3R_D]

You mean that instead of reaching the 1.75, I would decrease the 1.54??? (ie. 1.51)

[spooleffect]

Yeah, shortening the rod will decrease the rod ratio. The B16 has the higher rod ratio because it has a shorter stroke than a B18 and can therefore fit a longer rod which increases the rod ratio.

[M@St3R_D]

But how do I increase the rod ratio then??? If it's possible of course...

[spooleffect]

Fit a longer rod in by either shortening the stroke length or raising the deck(which is not gonna happen).

I'd rather keep the displacement and loose long term engine longevity than get a higher rod ratio. Your rings just might not last 100k with a 1.54 ratio, big deal. Rod ratio is not as big a deal as everyone says.

[M@St3R_D]

There's something that comes to my mind... If I put in longer rods, the valves clearance will be affected right?

[spooleffect]

Yep

[M@St3R_D]

But doing so, I mean increasing R/S, isn't a bad thing as well??? There's just some trade-offs to do right???

[spooleffect]

With the rod ratio specs you deal with in B series motors, you don't see a very big difference as far as benefits and downfalls of a higher or lower rod ratio. Like I said before, its not a big issue. You don't need to worry about it.

I'd be putting more thought into internals, fuel delivery, turbo sizing, intercooler setup, traction, and ignition timing, etc. if I were you. There are far mor important things to worry about than rod ratio in your case.

[M@St3R_D]

Ok I got it... I know that there are things far more important to take care of but, the fact is that I'm an EXTREMELY meticulous person so, I want everything to be perfect but sometimes it kinda becomes too much Thanks again for your input spooleffect

[spooleffect]

No prob, Im glad I could help. I am also meticulous but not if I don't need to be.

[redmanjd]

the rod to stroke ratio i basically only for longevity. it is th amount of force that is everted on the cylinder walls. you can run a stock b18b r/s with some iron sleeves and be perfectly fine.But if you want a b16 r/s my suggestion is to get a b16. Because your rod stroke also factors in your crank and rods.

[spooleffect]

It also affects the powerbands rpm range.