Hello all,
I'm new to the forum, and thought I would let you know of the project I have started. In brief, I will destroking the H23A1 I got from a 92 Prelude by using the crank and rods from an F20A and a set of H22 Type S pistons with a .025" overbore. Displacement should be around 2100 CC, Compression around 11.5 and the Rod/Stroke Ratio of 1.65:1. The closed deck design of the H23A1 block was crucial in my decision to use it as my starting point, and while I will not be going VTEC via an H22 head at this point, I do expect decent power out of it after some tuning has been performed. This engine will recieve all the typical goodies, Intake, Header, Exhaust, Crank Pulley, quality ignition componets, etc, but will not be doing head porting or cams, as I want to see what the difference just the bottom end changes make to the power before changing other parts. If anyone has any questions or comments about the build, feel free to post your thoughts.

The Project Car:
1992 Honda Accord EX (183,xxx + on the clock)
Eibach Pro-kit w/ KYB AGX
ST rear sway bar, EX front sway bar w/ upgraded bushings
205/55 Pirelli PZeros on 16x7s w/ H centers
Accord Wagon front brakes (11" vs. 10" stock)
No-name CAI
OBX header
2.25" mandrel bent cat-back

 

nice project.
d'you mean F20A SOHC?
Subscribing...

 

do f20a's share the same main's as an h23 or will there need to be machine work?

 

i would call it an overbored f20a dohc. i hope you are sleeving it with some sort of repalcement sleeve though since going from 85mm bore to 87.25mm is a lot for stockiron sleeves to handle.

 

you gonna end up reving really high to make any sort of power.....good luck with that

 

How is this going?? This project sounds very intriguing... especailly to accord people. I think the F20A has some great parts for us to work with. btw do you still have the rods and pistons from the F20A? I hear the dishes are shallower and the rods are longer than the F22A1.

 

Sorry about the delay in getting back to everyone. The project continues, although recently I had to deal with a slightly bent front subframe, as well as my long awaited 5-lug conversion. The head and intake porting is finally done, all that's left to do is machine work.

There have been some questions as to why I'm building the engine this way, I will try to provide some answers here. First off, this car is to be a fun street car, with occassional road rally and autocross duty, and coming this fall, The 35th Anniversary Cannonball Run! This combination is to be reliable, pump gas friendly, fuel effiecnt, and have good power (everything that Hondas are supposed to be!)


The F20A's 88 mm stroke and resulting 1.65:1 rod ratio is much better than the H23A1's 1.48:1, improving breathing, as well as providing more mechanical advantage during the period just after TDC, making the combustion more efficient. 11.5:1 is high for a street car, but because of the improved rod ratio, the engine can handle higher compression. With proper fuel and ignition tuning, it should run fun on premium pump gas. The size will be right at 2.1, smaller than the H23's, but mechanically more efficient with a smoother torque curve, and that is what I'm going for here.
As far as the bottom-end is concerned: The H23A1 block is a closed deck design with a factory bore of 87 mm. The H22 Type S pistons are sized 87.25 mm and share the same compression height as the F20A pistons. There is no need for sleeves in this situation. The mains are the same size as the H-motors, so the crank drops right into place without special bearings. The rod bearings of the F20A are the same as the non-VTEC B18 motors, and use the same ARP bolts. F20A Balance Shafts are also used, as well as an H22 Oil Pump as it is design for higher RPM use (and it will help push oil through the oil cooler.)
Cylinder head modifications: It has been my experience that a good flowing head with mild cams does quite well in a street application, so this engine will retain stock cams and the head has been treated to port work (reshaping the port floor, knife edging the splitters.) The use of cam gears will allow me to tune it in such a way as to take advantage of the revised bottom-end geometry (which actually encourages more lobe seperation,) and the higher vacuum (when the piston finally starts to move away from TDC) makes a larger port with stock cam work well with good flow, and good crossflow due to the amount of time at or near TDC, without the need for big cams or a lot of overlap.
Intake modifications: I'll be using an H23A1 intake manifold, with a recontoured intake plenum and 60 mm TB. The intake will be augmented by a 1" spacer (8-hole) between the butterfly unit and the lower intake manifold. The increased runner length will improve cylinder filling at lower RPMs. Throttle response and overall torque should improve as well, and a shift in the torque peak down approx 200 RPM, to an estimated 4900 RPM.

Hope that gives you an idea of the premise behind this build. I'll update again when there's more to report.

The Project Car:
1992 Honda Accord EX (190,xxx on the clock)
Eibach Pro-kit w/ KYB AGX
ST rear sway bar, EX front sway bar w/ upgraded bushings
225/45 Kumho 712s on 17x8 Acura TL wheels (with H centers of course)
5-lug conversion
CAI
OBX header
2.25" mandrel bent cat-back