F20A dohc hybrid build questions

[jasen klems]

Ok i am new here and i have just done a search on the web and found some specs and would like to ask some questions about swaping cranks and valves from other engines into the f20a dohc.

All right now first off these are factory specs ( i think ) for the cranshaft
Main journal dia. F20a 50mm Rod journal dia. F20a 47.95mm/1.888
F20b 55mm 44.98mm/1.771
H22a1 50mm 47.95mm/1.888
H23a 50mm 47.95mm/1.888

Now i realize that the f20b crank would be out of the question but i think the h22a-1 and the h23a1 cranks could in theory be swaped into my f20a. So the question here is this is it realistic to think this?

Next would be the valves i want to go with oversized valves and the valves i would go with would come from the h22a,1,4 as the valves are 1mm larger than the f20a the h22 valves are 35mm intake and 30mm exhaust.
Again the question is this realistic to think?

If you would like to know why im asking i want to build a turbo motor for future install.

[Jarrett]

The H22A crankshaft used 50mm main journal diameters here in the US for the entire run of the H22A1 ('92-'96) and for the first year of the H22A4 ('97). Any of those crankshafts, as well as any H22A crankshaft from another market that is '97 or older will work fine. You will also need the accompanying rods and correct-height pistons in order to make it work unless you're going with longer aftermarket rods and shorter pistons. If you use the PT2 pistons with the H22A rotating assembly then you'll be at 2059cc with 8.5:1 CR. A better alternative would be to bore the engine to use K20A2/K20Z3 pistons with this combo. That would yield 2107cc and 10.4:1 CR.

Also, the H23A1 uses the same crankshaft as any of the F22As or F22Bs other than the '98 and newer F22B DOHC found in the 5th generation Prelude base model in other markets. Again, that crankshaft will work provided you use the appropriate rods and pistons. If you used this crankshaft, you'd essentially be creating an F22B DOHC.

[jasen klems]

Any idea about cams i have not found specs on stock cams for the f22 dohc or the h23 i wouldi would think that i could find aftermarket cams for the h23.

And as far as lower compression of 8.5:1 that u stated for using the h22 crank with longer rods and shorter pistons wouldnt that be ideal for a turbo build or am i mistaken on that fact. And also i want to stay as close to the 2.0l specs as is realistic. My thoughts for the turbo are to use the stock 16g from a volvo s or v70r and run the stock boost of 15psi that those turbo volvos run.
I dont know how wise this is and if it turns out that it is unwise i will greatfully take recommendation as to turbo size and boost pressure. To be honest i am looking for some where in the neighbor of 280whp or so i dont know what it will take to do that as im still researching this idea. I do know that i want reliable and safe power as i plan on driving this more than not.
If it cant be driven then whats the point of it ( i cant stand a trailer or garage queen) no offense to anyone that may have either of those lol.

[jasen klems]

After a little more reaearch i found a set of crower cams for about 500.00 for a h23 they say they are designed for forced induction. I know crower makes good parts for v8 and such what is their history with imports they also recommend a set of springs and retainers for the cams.

If I can use the cams in an f20a do u think i can also use the springs as well?

[NWaccord]

After a little more reaearch i found a set of crower cams for about 500.00 for a h23 they say they are designed for forced induction. I know crower makes good parts for v8 and such what is their history with imports they also recommend a set of springs and retainers for the cams.

If I can use the cams in an f20a do u think i can also use the springs as well?

For your power goals I wouldn't even touch the block, especially swapping out cranks...that would be a lil extreme for your power goals on a turbo setup. N/A would be another story as a longer stroke would really benefit.
The stock F20A cams will make the power your wanting and more. I do recommend forged pistons and rods anything after 300WHP.
Yes you can use the H23A1 Crower valve springs on your F20A head . Bisimoto also caters to the F22B/F20A engines, offering heavy duty valve springs + retainers, Custom turbo & all motor camshafts, and piston & rod combos.

EDIT: If you do swap out cranks, I'd be interested in buying your F20A crank.

[jasen klems]

I am not trying to be extreme with this build idea just not wanting to do anything half a**d if u know what i mean. So my build will be overkill what is really wrong with that?

F20a dohc block and head, H22a crank, h22a rods, correct pistons ( which i havent figured out just yet), h22 valves intake and exhaust ( as they are 1mm larger), h23 non-vtec crower turbo cams, b series/h23 adjustable cam gears. To me that sounds like one hell of a turbo hybrid engine build. I'm no pro engine builder by any means but i want to have an engine that lasts and is easily upgraded as i want more power.

Now i still havent figured out what injectors to run, or intake manifold (best flowing) or if i should run a light weight flywheel. I dont even know if the turbo I want to run is the best option. But i found a shop that will do all the machine work i need and they have a guy that can do my tuning when the time comes.

[Jarrett]

F20a dohc block and head, H22a crank, h22a rods, correct pistons ( which i havent figured out just yet)

The "correct" pistons in regards to bore size, compression height and the desire to stay with an OEM option would limit you to the F20B. If you're looking to add boost then the cast construction and high-dome of that piston make it a less-than-ideal choice. You could go with any piston designed as a low-compression replacement for the F20B and be completely fine. WEre you to change absolutely nothing dimensionally then forged pistons are still highly recommended for a boost build so you haven't really dug yourself much deeper here.

h22 valves intake and exhaust ( as they are 1mm larger)

But the stem lengths are different. And in a boosted application, what's the point?

h23 non-vtec crower turbo cams, b series/h23 adjustable cam gears. To me that sounds like one hell of a turbo hybrid engine build. I'm no pro engine builder by any means but i want to have an engine that lasts and is easily upgraded as i want more power.

For much less money you could have Delta custom grind your F20A DOHC or a spare set of H23A1 camshafts into a custom profile.

Now i still havent figured out what injectors to run

This will be determined once you've come to terms with what your power goals are, the turbo you're going to run and to a lesser extent, the management you'll be using.

or intake manifold (best flowing)

Golden Eagle is the only aftermarket offering for the F20A/F22A/H23A1 flange pattern. Other than that there are the numerous tweaks you can do with OEM parts and adapter plates to fit the aftermarket manifolds from the H22A on. If your engine is the F20A DOHC then you share the same PT6 intake manifold with the F22A6. A P13 plenum and matching throttle body from either an H23A1 or H22A would do well toward increasing airflow.

or if i should run a light weight flywheel.

Is this car a daily driver? Are you okay with the driveability changes? If so, then it will help the turbo to spool faster by getting it into its effecting range sooner.

I dont even know if the turbo I want to run is the best option. But i found a shop that will do all the machine work i need and they have a guy that can do my tuning when the time comes.

Check out the responses above.

[jasen klems]

I thought it would be best to stay with the stock bore unmodified unless i had to resleeve the block. Not trying to limit my options at all here. Iam fine with using a low compression piston of the 85mm bore unless i have to increase the bore wich will also increase displacement.

The h22 valves wont work cool i didnt think to take into account the stem lengths. But oversized valves on a boosted engine would still be a benefit would it not. So there is a point to my thinking here. Anything that helps an engine breath better is good is it not.

The flywheel is not an issue really for me it will just take some getting use to is all. I have had light weight ones before but i will wait that one out.
Jarrett I thank u for ur input as well as e everyone else that has posted.

[Jarrett]

If oversized valves are desirable because they would "still be a benefit" then what's your argument for staying near a certain displacement? An additional .1L of displacement is going to help more than +1mm-sized intake valves, I can assure you. Unless your head is being ported and polished, or any other extensive work being done, I would put that type of modification on the back burner. I don't disagree that it will help, only that there are other modifications that can be done that will have a greater return on investment.

[jasen klems]

Ok thank i thought u were saying that the valves wouldn't be of help. I do like ur idea of using the k20 pistons what would u recommend for rods on that setup. As i said i want to do this right the first time. Also i am just taking a stab here i would need to resleeve my block for that wouldnt i.

I thought (not for sure here) that you wouldnt want to boost an engine with over 9.5:1cr or is it all in the tune.

[HappyGilmore]

Man there is some good information right here!!! I have also been wanting to get an F20A DOHC on boost as that seems like a practical swap and different one at that to do. My question is the header on the F20A the same as the F22B(DOHC)/F20B/F22A? If so then I want start collecting parts and begin this build!

[jasen klems]

From my research all the F series except the f20c work and also the h23 header and intake manifolds work as well. I think someone else can verify this but i have been sereaching on here and the web