rod ratios/ longer rod
 

So Im building a b18b in the fall for turbo and my girlfriends father is building it with me, hes a mechanical engineer and has been building racing street bike motors for years.

we got to talking last night about building the motor for turbo and what not and he starts talking about how were gonna calculate the ring thickness and rod ratio for the best piston acceleration rate for the motor.

I have been researching rod ratios and piston acceleration and I would like to add a forged rod to the motor that is 1 or 2 mm over stock less, this should minimise the piston acceleration rate 1.5-2% lowering the wear on the bottom end and allowing the motor to rev higher safely.

what is everyones knowledge about doing this, a longer rod and a shorter lower compression piston sould work fine in the block and work with turbo.

does anyone know where you can buy forged rods for the b18b engine that are 1 or 2mm over stock legnth? I can have them machined for me for a very reasonable price, but i would rather buy something off the shelf if this is available


rod ratios, piston acceleration and ring thickness's whats everyones opinions.... discuss

Re: rod ratios/ longer rod
 

holy ---- dude, you need to introduce me to your drug dealer :6


anyway, what is "high revs", seems like you may be getting a little too technical.

Re: rod ratios/ longer rod
 

umm high revs in meaning I would like to safely rev the b18 to 8200-8300rpm without worrying too much about blowing things... no worrys the motor will all be built to handle this as well

Re: rod ratios/ longer rod
 

Pretty sure the LS r/s ratio is the same as the D16, 1.52, which sucks. But people rev them to 8500 all the time. More important than investing in rods that nobody makes you just need to get ARP rod bolts and an upgraded valvetrain, then it will rev just fine. Don't get too technical, it's a honda.

Re: rod ratios/ longer rod
 

u want a better rs?
get a gsr

8300 isnt high really high for a honda

Re: rod ratios/ longer rod
 

i would love to skip technical stuff, but its just too interesting to skipp over... and my girlfriends father is dead set on building everything perfect..... which I dont mind at all seeing as he actually knows what he is doing and offering help for free

on the crower site they offer a b18 "stroker rod" with a C-to-C legnth of 5.564, which is over the regular 5.394 of the b18b, but i believe this stroker rod is for a Vtec b18 because the PE bore is 20mm not 21mm like the regular b18b rod...

Re: rod ratios/ longer rod
 

Stroking a motor makes the r/s ratio worse in order to increase torque. Seriously, I know it's a really fun topic but get some rod bolts and you can rev the bottom end all you want, seriously.

Re: rod ratios/ longer rod
 

just make sure you get an ITR oil pump and call it a day ::)

Re: rod ratios/ longer rod
 

Eagle sells the longer rods you desrie.......

Re: rod ratios/ longer rod
 

With a 2mm longer rod you are talking about a .03% decrease in piston speed, and 2% decrease in maximum piston acceleration. That's less than the difference between the B18b and B18c. It's not worth it. 8500 rpm's is not going to be that big of a deal if you select the proper components and build the engine properly.

The only way to really make a dent in piston acceleration is to decrease stroke. Im not completely familiar with Honda B-series engines, but (theoretically) you could use a b20 block, destroke it to 1.8 liters, use a custom rod, and custom pistons. You could play around with the rod length and stroke a bit, but you would probably end up with a rod to stroke ratio around 1.7:1. Is all of that time and money spent worth it? Probably not. There are advantages like less wear on the cylinders, and increased dwell time at tdc(which has multiple advantages in itself), but in a street application they are negligible.

Trying new things is great, but it rarely turns out the way it's supposed to. Concentrate on getting the clearances perfect, getting your quench area right, balancing, and matching parts that work well together.