Case in point:

In my B18C block that has been re-sleeved to 84.5mm and is using an LS crank (89mm), the displacement is 1996cc (1.996L)

If I use the Importbuilders long rod/piston combo will my displacement remain the same? Is it only the r/s ratio that will be changed?

Will I still get the torque of an LS crank or is it now somewhat similar to the GSR crank?

Also, what happens if a long-rod combo is used on a GSR crank (if this exists that is)

 

The length of the rod does not affect the displacement. Only the bore and the stroke do. With the long rod setup, the bore and stroke remain the same...you're just changing rod length and r/s ratio.

Sonny

 

Not a specific answer to your Q, but a good article none-the-less.

LINK

 

A lower R/S is set up for a torquer motor... That's why CRVTEC and LSVTEC have really nice bottom end... A motor with a high R/S ie.. B16A and the B16B and 1.74+ are more high strung making nice hp high but losing bottom end... I would personally stick with a B18C it's R/S of 1.58 is good enough for me... I like to keep the R/S ~1.60 or so but the known perfect is 1.75 which doesn't do it for me because of the lack of torque... I've never looked into the importbuilders blocks... When you say long rod/piston combo is that a block with a deckplate or just a little bit longer rod with w/ a high mounted wrist pin?? My guess is for either that if you use it with the LS crank and it bumps up your R/S a considerable amount then you are gonna loose torque... If you did this to a B18C to a certain amount then you are going to have the same loss.... Personally I would just sleeve out another 0.5mm from what you said to 85mm then just keep the GSR crank and rods and high compression pistons (for all motor purposes)... That's ~1.98L with the added strength of a B18C crank... Just my opinion... Hope this helps...

 

hmm i don;t get it?? With a logner rod though won't the piston move further up and down in the block? Isn;t that the smae as (for example) chanign from a GSR crank to an LS crank. Jsut another method of moving the piston up and down further (AKA Stroke)?
no?

 

it amazed me to think that Formula 1 cars and racing motorcicles are around 2.1 on R/S ratio!

 

What creates vertical piston motion is the rod journal offset from crankshaft centerline. Without this, the piston wouldn't move at all regardless of rod length or anything else. Rod length simply defines the behavior of that movement relative to crank rotation, in that a longer rod creates more dwell time after TDC and less after BDC. It also diminishes angularity, which is in fact the source of the difference in dwell times to begin with. There's two older threads on this exact subject I've contributed to in the Tech forum, try a search for more details as well as position/velocity plots of piston movement based upon rod/stroke ratio.

 

To answer your actual question. What no one actually did for you is yes it affects your torque by quite a bit. Depending on your other adjustments, (such as compression, cam lobe height, and duration, porting) your torque curve will move up and if it's VE is improved your torque will increase at it's peak. My own example works quite well it's 1.75" taller than stock. I haven't had the money to dyno it yet, but when I do I'll post the sheet.

Just so you know, with a racing motor you want the torque farther up and higher, and you us gearing to make use of it. There's more to cars than just math children. Math is what your use to build it stronger. Imagination is what makes it work better.

 

cool, i think that cleared it up for me

 

Even more importantly then how much power or torque the motor will make...the r/s ratio effects WHERE it will make power. F1 cars rev to like 18000 rpm's so their r/s ratio is going to be higher...just like bikes.

Hondas were made to rev in my opinion.

Rod length has zero effect on displacement. I say again. Zero.

 

Also don't forget when you put in a longer rod, you are also changing to new pistons with the pin set higher in the piston. The bore and stroke remain the same.