Best choice for 00' Civic Si engine swap(replacement)

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So I decided to derive the piston speed as a function of crank angle. The b16b and b16a are nearly identical, the b18c's are 12% faster at peak resulting in 25% more Kinetic Energy (KE). Most interesting is the load at max rod angle from horizontal. The b16a has 6% more than the b16b, and the b18b 12% more at 90deg from TDC. But remember the 18b is making more torque, so the total load on the side wall is 26% greater for the b18s over the b16b. So basically the cylinder walls and the rods are experiencing ~25% greater stress for the b18c's. And I haven't considered the effect of the increased speed of the b18c's on the lubrication and cylinder wear. The CTR and ITR being nearly identical in build and rev limits, the ITR is a way more stressed engine. Not saying it's not good mind you, it's an amazing engine.
 
Sorry.....I didn't write the question correctly...how did you take the r/s ratio and find the rpm limits??
 
Got it. Those are the limits imposed by the stock ECU's (honda) from the factory, not the physical limit the motor is capable of. I was just gathering the information in one place to see the trend in R/S ratio and where Honda sets its ECU limiter. The F20C and B16b are both over 1.8 R/S and allowed to got to 9k, the others are capped around ~8k with R/S ratios in the 1.6X range. The ITR is the anamoly reving to almost 9k with a R/S lower than the others. Just thought it was interesting.
 
i would think it has more to do with the cams and valve train limitations than the physical or geometric limits of the crank block rods and pistons
 
OP: I see what you are saying.

I agree with E
I always thought the rev limits were based on valve train limitations and/or the stretching of the rod/crank bolts under s higher revs, friction.....heat. I would think those would be probable points of engine failure before R/S ration would come into play.
 
I would think the best choice for a replacement motor would be a GSR or a ITR motor. They have the higher hp and are both simple swaps.
 
The primary limiter is the strength of the rotating/reciprocating assemblies, valve, springs, rods, etc. these all result in catastrophic failure. Average piston velocity is a function of the stroke, the linear distance it must travel in a revolution. However the max piston speed achieved and where it occurs in the crank cycle is determined by the R/S ratio, as is the side-loading (friction). So the R/S effects the overall total engine stress, with higher ratios being better. I wonder how much of Honda's limit setting is based on wear/longevity vs rod and valvetrain limits.

The GSR gives the most low end torque, b16b gets it up top. The ITR would be the ideal, but it's much more expensive. In the end my decision ultimately got tipped to the CTR b/c of legality issues, it's legal to swap it as it's the same year and disp. as my civic and was about the same cost as the GSR.
 
I really enjoyed reading this thread as I was debating between the gsr and itr myself. I honestly don't have enough for the itr but have available credit ha ha. I will feel better though now getting the gsr. Thanks to all of you for your info. I'm sure that I will have questions during my swap in a couple months.
 
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