Recently got told about a Cb7 with an F20B, went to see it, found out it was an F20A, which only disappointed me a little bit, and I still plan on getting the car. Been doing alot of google'n and I haven't seen many answers on the subject...but it is possible to Put F20B pistons on F20A rods? Or better yet the F20B RODS & Pistons on the F20A crank??

I have a Fully built H22 head I plan on putting on as well so I'm not really worried about that but my goal is to net that 11:1 compression. Any tips would be appreciated. Any insight to the potential of this motor would be appreciated to.

 

Either boost it, or swap in the H22. Dont waste your time.

 

I'm with Arthas on this one..

That said, if you are boosting the F20A head responds very nicely to porting..

 

That was my first reaction, especially considering I have a Fully Built and Stroked H22 in my basement---But that's for Honda-Day for use in another chasis. The end result of this car will be an all-motor J37 (I got the motor from my brother before he went back on tour from his wrecked TL)...but that's just intention, having the motor and trans only puts me halfway to that goal...


My Main reason from not just going H is Funds -vs- Free. I already have bits and pieces, F20B rods and Pistons, even an F20B Head and a spare Built H22 Head. Keeping in mind that the Shorter Bore gives the F20 platform a bit more head room as far as it's rev ceiling (I've never taken a Stock H over 7400, the thing stops making power @ about 7500 anyway, maybe even sooner)..where as I've seen a few F20A's and F20b's taken nearly to 8 grand making power still (I'm not here to rev to the moon, but knowing I can stretch a gear or two is peace of mind)...

You don't think that An F20a with F20B pistons + F20B or H22 Head could stand to be a better outlook..Considering that IF I decided to use my built Head, I could DEFINITELY spin the thing to 8000+ (I intend on shotpeening the rods, upping the Oil pump and ARP'ing the connecting rod bolts, wrist pins and Head studs) making power...For CHEAP...


200+Crank horses/150+crank torque @ Free.99 (parts) + Labor (250-max)

vs

200 Crank horses/160 crank torque @ $750-800 on entire H22 Long block....We'd have to agree taking the time to put this thing together is more cost effective right?

 

what makes the f20b pistons and rods superior?

 

Higher compression = More power, and cheaper as in free because I already have them.

 

Answered my own questions..the pistons mate to the rods with no issues, no clearance issues, totally fine fit.

 

The rod lengths will be the same for the F20A and F20B. The bearing thickness has yet to be determined as far as I've seen but the F20B uses a 48mm big-end bore. So you MAY have issues there if the F20A is still 51mm. Only the piston swap will actually change anything and will yield around 11.8:1CR with the 50CC head. 11:1 with the F20B head.

As for the built head being used on this block, don't do it. I can't stand when people do this swap on 85mm bore engines. Mostly it's idiot Accord owners who want to be able to pop their hood and see "DOHC VTEC" without actually knowing how to build an engine or doing any of the work of a swap. Also, they're cheap as hell. I understand a lot of people boost this combination(I still don't agree) but to do this N/A would just be wrong. The bore offset is a breeding ground for the formation of hot spots and is detrimental to there being any sort of quench happening in that engine. Here's a post I did on CB7tuner after the 1000th person asked about it that week.
http://www.cb7tuner.com/vbb/showthread.php?t=187140

Stick with the F20B head. Honestly, unless it's got lots of portwork done, what's really "built" about a head that can't easily be done to another one?

 

Head has Sk2 Stage 3 Tuner Series Cams, Full Titanium Dual Valve Springs and Rocker Arms, Retainers and keepers with oversized Valves (Intake and exhaust) and a full port n polish with Sk2 Adjustable cams....

Honestly I think you bring up very good points. If I had an f20B head i'd throw that on this in a heartbeat becuase the compression + Vtec would sate my inner-noise-wanting-demons that crave that sound and high end performance lol ,and I would't have to tune. I think i'm going to take the advice of having this stock F20A (it's DOHC) ported and polished and MAYBE at best a super-tech head kit and call it a day, it's cheap and it means I won't have to see a tuner or do any type of drastic alteration..I appreciate the advice man..think i'll just swap out pistons, do head work, call this thing a wrap.

 

I'm confused.

But yeah, an F20A isn't a bad animal in and of itself. Lots of people on CB7tuner have them in their Accords. Do you know if they has the PT2 installed as well or is he running it with a USDM Accord ECU?

 

I'll clear up the confusion, The head in my possession is a Built H22 head, not an F20B head..I was gonna drop the pistons in with THAT head, but you've given me reason to just opt and find an F20B head or Leave the DOHC F20A head that's on it now..


As for the ECU??? Haven't even checked, the car is just sitting here right now and I haven't so much as waved a screw driver at it. I guess i'm just kinda finding my direction before I go. Once I touch a car with a plan I go from A-to-B without hesitation so..Im gathering data and pointers.

 

Jarrett, what's your take on the F20A DOHC stock thought?? Does it move the car any better then an F22 or h23??? Equally so?

 

Ok so I finally got to get my hands into this car a lil bit...came across a few issues I may need some help on...here are some pics.




This plug isn't plugged into ANYTHING and I can't find sensor or anything it might plug up to, any ideas?



Should I be worried about this?? It seems like a Camshaft position sensor with the wires and plugs clipped. Now I understand that the F20A was originally ran an older body style, since this one is in an obd1 chasis and using an obd1 dizzy is the CPS accounted for differently hence the clipping??




Just a shot of the whole engine bay..




The whole car...





Video to further any diagnostic tips on my issue...


Also, it's running off of a PT6 Ecu, is this the proper ecu?? The car is having a surge at idle, could be a vacuum leak but the original onwer informed me that there was an exhaust leak and that could be causing some of my issues, but I still think it's a vacuum issue. Any tips would be appreciated.

 

New to the group. Question is that the F20B on F20a block seeing in pics?

I do too own a Honda Accord. 1990 CB3 with a F20a5 engine. I broke my head by accident when I was making some adjustments so finding a new head was the new task. Seeking to get more power out of the car so I was looking to get a better head. Found a F20B Dohc vtec Sir but with all these readings I'm doing now it seems I have 2nd thoughts altho I am a bit confident that the build should be ok. Read that the F20a blocks more suitable for the F20B/H22 head but still some not so confident in it. Is this due to persons not being able to play around with the F20b as much as the H22s? If in the event a person can get the F20a block to get the desired compression (11.0.1) would a F20B head work?

Its not that a dude is cheap but I don't have much cash really. The aim before tragic break in on car and the head breaking was straigh H22 or K204/K20z engine with lsd gearbox to match.

How different is the F20B block from the F20a block?

Since my engine is sohc and the head is dohc I know whts needed so far. F20B head complete,F20b/H22 engine wire loom,H22/F20B fuse box,Ecu wireloom,F20B/H22/P28 ECU,bottom half gears with timing belt to match. (If I'm wrong I'm wrong on here to widen knowledge).