Has anyone here tried to bore the L15 engine out a bit?Please relate your experiences if you have... and also share any reasons why one might not want to do this.

73x 89.4
a) seems severely and obscenely undersquare.
b) is leaving roughly 100cc on the table in the 1600cc N/A racing class.

Seems to me that 75mm pistons would give about 85cc more and free upa little margin on the perimeter of the combustion chamber to unshround the valves a bit (go a bit bigger on the intake as well).

Thoughts?

 

I am so far thinking about just increasing compression in the pistons, no other block work. Since the block is aluminum, the cylindersmust be sleeved.

Could the cylinders be bored out without switching sleeves? Probably an important (and potentially expensive) question that needs to be answered.

Also, I read somewhere that the L15B1 goes under an arduous balancing process. I was wondering if it would be wise to balance rods, pistons, and crank if rods and pistons were replaced. And additionally, wondering if there is a balancer shaft, and if there is, can it be removed. A lot of times the balancer shafts are there to make soccer moms etc happy, and the engine idle is not that rough with them disconnected (speaking from Mitsu 4G63 experience).

Let's go! I want to max this block out NA style!!!

 

EDIT: This post was directed at ZO62FIT

This isn't exactly something you are looking for, but have you looked at lasleeve.com? I would imagine them to be the type of company that would enjoy adding a few extra cubic inches if someone was interested.

These engines are already high compression, so looking for cc's or ci's seems like the best option after the world of lesser expensive bolt-on performance has been explored. Any idea if these cars react well to a lighter crankshaft pulley, aka underdrive pulley?

Curious since I don't follow along super close... Is this car only a toy at this point or just on track to be? I ask because I am curious how much weight reduction you have done before track days.

 

Yeah, I suspect the L15 block with not much of a high performance following (other than China) would require somebody willing to cut the current sleeves out of a block, and then fit thinner, bored, high performance ones in there. This is pretty far outside my knowledge base other than basic mechanical engineering and physics. It's just much easier to pop out pistons and replace pistons, rods, rings, and rod bearings. But yeah, a bored engine, and a knife-edged, weight reduced crankshaft, and then fully balanced assembly would definitely net a significant gain with the corresponding top end modifications. With all that stuff, we're talking way more than a K-swap. I'm going to do top end stuff and piston/rod stuff. If that is hugely successful, maybe I'll start on the bottom end when I pull this block. I decided to push off the headwork for more suspension upgrades which were needed and provide an immediate impact. So, it's going to be a while.

As for the already high compression, they are, but they are also catering to 87 octane. With the Ktuner tune, one can go higher on the compression and run 91 like me, and one can secure a flexfuel sensor and run E85 which I also plan to do.

With regard to weight reduction, it's my daily driver, so I just pulled the back seats, and that's all the weight reduction I've done. My race wheels are 11 lbs vs 20 so there is that, and it's unsprung weight. You can see what all I've done in my build thread in my signature... Cheers!

 

Update: I am looking at Golden Eagle Mfg out of San Dimas, CA for sleeving the block.