Honda-Tech - Honda Forum Discussion - All Motor / Naturally Aspirated

Compression ratio limit for stock B18B rods

acr_8133 — Tue, 12 May 2026 06:33:00 GMT

Hi, I will be buying aftermarket high compression pistons for my LSVTEC and they say it will make around 12.1:1 CR with my head-block combo. I'm wondering if the stock B18B rods will be able to handle that high. This is a daily so I won't have it tuned to the limit.

Shortening PLM cat

GagnarTheUnruly — Sun, 03 May 2026 15:09:59 GMT

I'm just getting around to installing the exhaust on my swap and I find--not surprisingly--my PLM cat is too long for my PLM header. It's one of those adjustable ones that I hoped would start off short but its the same length as the stock cat, so with the new TA header I'm about 2" too long. What's the best way to fix it? Do I have an exhaust shop trim the catback? Can I pull out the flared end of the cat, cut it off ahead of the bung, and hammer it back in? I don't have any experience with these types of cats.

Do i really need a arp 625 bolts for my k24a2?

donaldand — Tue, 28 Apr 2026 11:31:30 GMT

Hello guys im new in here and a newbie building my first engine, so im really inspired by diymike channel on youtube budget build, i have k24a2 with its original head and will do some mods in it:
1. Skunk2 stage 3 cam
2. Supertech valvetrain set
3. Supertech forged piston 87.5mm 12.5 comp(i actually want to use nippon racing 87.5mm type s cast piston but a guy in other forum told me to get a forged piston to if i want my motor to last in drag races)
4. Maxpeeding rod this come with arp 2000 rod bolt(i was gonna use my original rod but my it is quite rusted and have some kind of stone like sludge in its body)
5. 4p type s oil pump
5. Ati super damper
6. Action clutch lightweight flywheel
7. Acl race or king race

I hope this setup will get me to 300hp ish and i understand due to long stroke of k24, this engine doesnt like high rpm and im fine with it, a guy told me to get arp 625 rod bolts if i want these to lasts a lot of 8k pulls, but the price of arp 625 is quite expensive about 400$ i think the bolt is 3/8" 1600"?
Do i really need arp 625? I think its quite a mild build my setup?

This is the pic of arp 2000 that come from maxpeedingrod

Skunk2 Alpha TB in ITR vacuum connections

GagnarTheUnruly — Mon, 27 Apr 2026 04:26:08 GMT

Hello,

I'm swapping a JDM ITR into my previously GS-R-swapped LS. I'm nearing the end of my swap and gotten all of the electronics and coolant lines connected.

The throttle body is a Skunk2 Alpha B series and the intake is a ported ITR. I'm following the typical ITR setup as near as I can determine.

The lower firewall-side TB coolant port is connected to the passenger side of the IACV, with the other IACV port connected to the copper coolant bypass on the block. The lower front-facing coolant port is connected directly to the small coolant port on the IM flange (I'm not using the weird pipe that's welded to the valve cover breather).

For the vacuum system the PCV valve is connected to the nipple on the front center of the IM. The firewall-side center nipple on the IM is connected to the brake booster. The firewall-side nipple closer to the passenger side (directly over the IACV) is connected to the purge control solenoid, the other port of which is connected to the vapor canister. I'll connect the valve cover breather to a CAI.

All that leaves a single vacuum nipple on the top of the throttle body right next to the MAP sensor. I know this isn't there on stock ITRs. How do I connect it? I can't remember how my GS-R was and the Helms manual has me confused. I'm struggling to understand the vacuum diagrams. Do I cap it? Tap it into one of the other lines?

I know this is a stupid question. I've tried searching for this but I keep coming up confused.