Heya!

My brother and I have a Type S H22A and a Base JDM H22. We're planning on trying a turbo build (first time) and would appreciate some advice on which engine to Turbo. *We're planning on doing a compression test and a leak-down test first before everything else

I've done some research and here's what I found
1. Type S is an open deck and the Base is a closed deck. Answers I found were mixed on which is best but most of them suggest to turbo the Base since it has a closed deck design but I also read some that if it's going to be rebuilt, it doesn't matter if it's an open or closed deck.
2. Type S has an ATTS transmission which is not working and the Base has an M2T4 LSD Transmission. We're planning on swapping the LSD from Base to the Type S if ever.
3. I've read that Type S has better internals which are; Type S Forged Con. Rod and Pistons, Type S Camshafts, etc (what else?). The head is also ported and polished from the factory. Larger diameter TB.
4. Compression Ratio is 11:1 on Type S and 10.6:1 on the JDM Base.

Here are my questions and concerns if we go with Type S:
1. Is the Nippon Type S Pistons the same as the one on the Type S H22? If so, are we good on the on the rod and pistons since it's an upgraded one? It's also $600 so this a good thing right?. Probably still going to have it resleeve though (or not?)
2. ATTS needs fabricating to eliminate and have a bracket in place for the half shaft, I've read of removing the ATTS and doing a stock H22 Trans but not an LSD one, will LSD work on the block? (We could also leave the ATTS not working and work on the transmission it came with which is an M2U4. They have the same specs as the M2T4 except for the LSD.
One reason of ours to also swap the transmission is to save money and time on what axle to use since Prelude Type S isn't available in our country. We're planning on using the stock Accord ones.
3. Are there any internal upgrades needed? or could we rock with the Type S? Will it work on Boost? What exactly did they mean by it doesn't matter if it's an open or closed deck if it's going to be rebuilt? I've heard of doing a block guard on the open deck but will it be the same as the closed deck in terms of durability?
4. I'm leaning more toward the Type S since we don't have that much of a budget and I'm thinking since it has already a Forged Rod and Pistons and other better internals, we can save more $$ on internal upgrades. What do you think?
5. The CR of 11:1 is also another concern as far as I've read.
6. What's more budget-friendly but doesn't compromise durability?

We're looking for a 400whp, is this a safe number? The car is gonna be Daily-driven.

Thanks and we appreciate any input!

 

The Type-S does not have internals that would make it better for a boosted application. The rods are the same as a typical H22. The pistons are different but they are NOT forged, they are still very fragile cast pistons. They are an inferior casting to the Nippon pistons by far. They do have better valve springs and more aggressive NA cams but that's about it honestly. Both of those things will make little difference when adding boost to a fairly stock engine. Plus if it's a USDM Type S engine, the cams are very close to the Base JDM H22 cams. The stock pistons can barely handle 300whp before crumbling to dust, and the stock rods will only hold 350whp or so.

Since the Type-S is pretty rare/expensive now, and also ATTS, I would recommend not using that one. Either way...400whp even semi-reliably out of a stock H22 is basically going to require a full build with a sleeved block. Mahle golds with stock sleeves are an option but seriously hit or miss and I have heard much more bad than good about them in the past 15 years or so. The cheapest route would be to use the Nippon piston package with their custom H beam rods. You wouldn't have to resleeve but you'd still be taking a calculated risk with the pistons beyond what they're rated for.

 

Ah that clears a lot of questions in my head.

So what do they mean by Type S Pistons here on the forum, they are referring to the Nippon ones or the ones in the Type S H22?

I'll probably go with the Base then but not use the Nippon Pistons since they are high on CR. I don't think I can find a good tuner around in our area so that's a big concern for me too and I want to avoid tuning an 11:1 CR.
I think I'll go with a tested lower CR Forged Piston and an H Beam Rod and sleeve my block but I'll do the math first.
I'm thinking of leaving the Head stock since a lot of people made it with 500whp+

 

They are probably just referencing OEM pistons. For a long time you could get brand new OEM Type S pistons from Honda but I don't believe that's the case anymore.

High compression is really not an issue anymore with a competent tuner and good fuel or water/methanol injection. My current F20B stroker is 10.2:1 and I had a built 11.5:1 single cam about 9 years ago.

I would at least upgrade valve springs and retainers in the head. Use steel retainers if you plan to put a lot of miles on the car. Titanium requires adjusting the valves fairly frequently.