I haven’t been able to find much info on this topic here or on Honda-Tech, if anyone know of a thread that I may have missed please feel free to tell me I’m a dumb ass and point me in the right direction. :uhoh:
I’m picking up a B17 short block from a buddy in town. My original plan was to build the bottom end for road racing, and wanted to up the displacement as much as possible. I was originally thinking that I could just bore and stroke it with GS-R (P72) crank and rods, however upon further research this won’t be possible based on the short deck height.
I’m wondering if anyone has had experience in building this bottom end, and what components they went with? Based on what I’ve read, sleeving to 84mm would net me around 1.8 L of displacement on the stock rods and crank. I currently have a P72 head with Skunk2 Tuner 2’s. Any info/experience would be highly appreciated.
If you’re looking for displacement, then a b17a block really isn’t the place to start. Do you just have the bare block or is it completely. IMO with how rare the b17a is getting I’d keep that thing as factory as possible, maybe even just hoard it. Personally I’m a huge fan of just bumping the compression to 11:1 and using all OEM parts. Basically you end up with a 1.7l ITR engine. That’s how I had mine built and I loved it (until it blew up ).
One thing some people were doing was putting a b17a crank into a b20 block and getting an amazing rod/stroke ratio but more displacement than the short deck b series usually provide.
If you already have a p72 head then I’d just try to pick up a b18c block or even think about an LS/vtec or B20/vtec setup.
I’ve been thinking that. The motor that’s going in for now is a B16a bottom end with the P72 head (it’s what came with the car). My buddy has a B17 bottom end fully assembled (crank, rods, pistons, etc) that I’m picking up on the side, since the DB2 needs B17. I’m thinking refresh and swap it out and sell the B16 block, but part of me wants to send it off and sleeve it to 84mm.
I really just want a nice flat torque curve that will pull out of the corners well at the local track events. A lot of B17 dyno numbers I’ve been seeing don’t seem to have much low-mid range torque.
How much time have you spent on track before? Unless your answer is that you have dozens of track days and many years of experience then you’re barking up the wrong tree. You don’t need more power and really in a best case scenario you should have LESS power. Modifications, specifically power and tires really help mask driver ability and make it more difficult to learn. Having power to pull yourself out of a turn directly inhibits your ability to learn how to carry momentum through a turn. I see this all the time at the track with guys in fancy sports or super cars. A stock b17a is more than enough to get you started. Even a b18a would be more than adequate.
Here’s the dyno for my b17a, it’s the engine I had when I first started tracking. Very simple and conservative build which was way more than I needed as a beginner.
RED = how the car came into the shop, running a chip tuned for someone else’s b17
GREEN = the tune I left with
BLUE = the same tune as the green line but with a velocity stack and no filter. Tuning would be able to take out the majority of the big midrange dip you see. After that run I took my muffler off and was able to hit 200.2hp at the hubs - but again, no additional tuning.
Wow those are really good numbers! I wasn’t expecting to see that much torque out of the 1.7
Thanks for sharing your experience! I probably should have clarified my time frames on all of this. I’m going to be running the B16 for awhile. It will definitely be the motor I’m doing my first track events on, and I was planning on running it until it fails. The B17 build is something that’s more of a long term thing on the side.
I do have a spare B20 laying around as well, perhaps I can figure something out more along those lines, maybe the B17 block gets turned into a coffee table, haha.
).