Whatsup! Just picked up my first Prelude (gen.5) and I'm trying to build a decent and low key turbo setup. I want the least amount of headache since I'm using my shop where I work to piece it together. It's a base model, I heard H23 would be a decent motor to handle a measly 10-14psi and not grenade if I don't beat the **** out of it.

 

It looks like you have a H22, not the H23. I think all preludes for the generation/body style you have include the H22, which is a better engine in my opinion. The H23 was on the previous generation entry level models.
As far as what your engine can handle, I think 8-10psi from a average size T3/T04E turbo is safe as long as your engine is in good condition and you have your fuel tuned slightly rich (12:1 air fuel ratio about) and you decrease your ignition timing about 1/2 a degree to one degree per pound of boost (so about 5 degrees lower than stock). So you could probably make about 270 horsepower safely and it would be fast, if you want to keep it low key like you say.
You’ll need to decide what to tune with. Since you’re OBD2 it’s a little more tricky and I’m not sure what options are available right now, as I haven’t done any OBD2 preludes.
10-14 psi: do you have any turbochargers in mind, or certain turbo kits?
Also, I might have missed it, but your car is manual transmission hopefully, right? Honda automatic transmissions generally can’t handle big power.

 

To add to/clarify some of this. The H23 was actually in the midrange 4th gens. The base models came with an F22A series, same as the CB7 Accords.

PSI is irrelevant. Total power output and delivery is what will matter on a stock engine, moreso on a stock H22 with what appears to be high miles. I would keep it under 300whp and tune out as much torque in the low/midrange as possible.

The tuning figures posted here are what I would consider aggressive for a stock H22. ANY, and I mean ANY, amount of detonation in the engine will cause the ringlands to crumble into pieces. Realistically on pump gas, with a stock H22, you want to be in the 11.2-11.5 AFR range in boost and 1 degree per psi of retard for basic setups.

OBD2 Preludes tune the same as everything else. You just need a conversion harness to step down to OBD1. Alternatively you could use any of many good standalones available today. This assumes a manual transmission, as you will not be able to tune an automatic car without much hackery and less than ideal solutions.


That said I've been doing this for over 15 years now and I stopped recommending boost on stock H22s long ago because they are very finicky and fragile. These engines are also much older now which doesn't help their case. If you must turbo a stock one, you will end up with problems. Maybe not immediately but you will drastically shorten the engines lifespan. You can mitigate some of this by tearing down the engine and opening up the top ring gaps considerably. Alternatively there is a relatively inexpensive way to build them and keep them reliable in the 400-450whp range and retains the factory sleeves. Nippon racing makes a cast piston for H22s that is a better design and made out of a superior alloy(same as Mitsubishi OEM turbo stuff) that they then pair with a set of forged rods. That would be the best route for a mild street car.