I'm trying to decide on which block to build next. This will be going into a turbo civic with a 60-1 turbo. Whats better going with a sleeved 1.6 with 84.5mm pistons and keeping the 1:71 rod ratio and reving it to 9500 or sleeving a b18c1 block with the same pistons and only spinning it to 9000. Will the better RR make more or less tq? I would think that a longer rod would make more tq and if this is true would it produce anywhere the same tq as a 2.0 gsr motor?

 

Turbos love displacement.

 

the more displacement, the faster the spool

 

if youre talking about the B16A, thats a 1.74 rod ratio by the way. And as far as your rev limits, where are you getting these numbers from? Are you calculating piston speed or side load to find these numbers or looking at others dyno charts with respective setups? And a longer rod will lower respective low end torque due to a lower piston speed. But the piston will in turn be more "comfortable" at higher RPM and the slower moving piston will also offer a wider tuning window. The B18C1 has a rod ratio of 1.58, which is a bit of a compromise, but when you think about it a sleeved block is a sleeved block when you are runnig on the street, it all depends on the boost you intend to run. Of course the higher rod ratio will naturally place less stress on the rings and cylinder walls as well as other parts of the motor, but at a slight sacrifice in low end torque, the torque does have good advantages though, such as the ability to get the "jump" on the competition and, like said before, spool the turbo faster. In the end, its your motor and your decisions, just keep in mind, when designing a motor for its preliminary start (this meaning BEFORE further modification and fine tuning of its more critical and less noticable parts) it is best to pick the turbo based on the motors configuration not vice versa.

 

It depends on what you are trying to achieve hp wise. You can take a B16 with a 1.74 rod ratio or a LS/VTEC with a 95mm crank and a 1.44 rod ratio and obtain similar horsepower figures. Before we even think about rod ratio we put the piston pin where it needs to be and have the ring packs positioned according to how much cylinder pressure there will be. At that point the rod ratio is what it is. Then we decide on the right cams to put in there depending on how long the piston is going to dwell at TDC and what kind of clearance there is for the valves. Of course we try to stay away from anything below the 1.4 rod ratio if we can. My point is, if you are going to sleeve it, then by all means go 84mm. As for the rod stroke ratio, I really don't think you will notice the difference between a 1.74 and a 1.54 once you are making big power. But keep in mind that camshaft selection and camgear tuning will be different according to different ratios.

 

Holeshot: How exactly do you get 509whp out of a GSR motor daily driven ?