ej_b16a

I'm planning to do a h2b swap with an H23a blue top in my eg trackday civic.
I want to use the stock bottom end with pro 1 cams, valve train upgrade and some good bolt-ons aiming for 230-240 whp.
I know it doensn't have the oil squirters and on the racetrack it sees the redline very frequently. I really want to keep it safe. What's a safe rev limit to maintain for the bottom end? What's your experience with this engine on the track?

kingofbattle909

iTrader: (6)

300

Aradin

For your NA application, you should be more worried about piston-to-valve clearance. The stock H23A blue top pistons have very inadequate/badly designed valve reliefs when using bigger cams. I would recommend switching to Type-S pistons if possible...or keep the stock cams. There have been many, many cases of piston-to-valve contact with aftermarket cams in these engines. I only have hands-on experience with 2 of these. One was in an NA prelude around 210whp and revved to 7800 constantly. Broke 2 ringlands in the end but rods and bearings didn't seem to care about the RPM. I had a boosted one around 350whp and it casually snapped a rod one day. Wasn't even in boost. When I tore down the engine I found 2 trashed main bearings and another bent rod. I was only revving to 7200. Bottom line is rods seem to be pretty weak so I wouldn't push your luck. For NA the pistons will more likely become an issue before the rods do. Lack of oil squirters isn't really a big deal so I wouldn't worry about that. Also the whole bottom end was made lightweight to offset some of the stresses caused by the longer stroke. The crank is the lightest of all H/F series cranks and the rods appear to have had some material removed in key areas to save weight. I would probably stop between 7500-7800 for an NA setup.

gmcuajo1

So the type-s pistons have more valve clearance than the h23 vtec do?

But what about that the type-s pistons are 31mm compression heigh and the h23 are supposed to be 30.55mm? Are still the h22 type-s safer?
Why?

Aradin

This is an H23A blue top he's talking about. Not a USDM H23A1. The H23A blue top pistons use the same compression height as a factory H22 piston. The H23A blue top rod is slightly shorter @ 141mm(instead of 141.5mm) to account for this. The Type-S pistons would bump the compression from 10.6:1 to 11:1 but the main thing is the valve reliefs are a better design which give better valve clearance.

gmcuajo1

Ok so you are just repeating what you think it is or what you heard?

H23A have a 141mm rod, you are wrong. Can be slighly shorter but not as much as 0.5mm.

Besides I know what is an "H23A blue top."

Definitely asking to the wrong person. Thanks!

Aradin

I'm repeating facts. I've had more than my share of hands on experience with all H/F series engines over the past decade. I have had the PT3(USDM H23A1, F22) rods and PDE(H23A blue top) rods side by side and measured, compared, etc. The PT3 rods found in the USDM H23A1 and F22 engines are 141.5mm. The PDE rods of the H23A blue top are 141mm. Go read through the "H23A blue top mystery motor" thread in the Prelude forum and educate yourself. This has been discussed and proven by many people other than myself as well.

Vtec04

If you keep it at 0, failure is impossible! But to be serious, the start of redline is safe, it is set well below what your engine can actually withstand. Keep it below redline and no harm will happen.

dpine

Ask yourself this question. How reliable do you need your engine to be and for how long? How frequently are your going to be on the race track? Are you going to beat on the motor daily?
Obviously if you keep the RPM's down it will last forever and vice versa keeping it in the upper RPM's all the time (on track, on the street) will shorten the life of the engine much faster regardless of camshafts used.