The K20a3 Discussion thread.

[Daschicken]

Originally Posted by Stacygifford

If I'm not mistaken in the 2200 to 3400 rpm range I believe the K24 has a lower BSFC But I could-be mistaken... I would have to find the graphs again ,At very least they dirt cheap and more readily available engines

What do you mean AGAIN? You found K series BSFC charts?!?!?! WHERE?

[Stacygifford]

Originally Posted by Daschicken

What do you mean AGAIN? You found K series BSFC charts?!?!?! WHERE?

I feel absolutely stupid for not saving it.. . It was a couple of years ago and it was some publication showing how the Cam phasing improved efficiency Across 2 or 3 engines. Almost all of it was in Japanese .Including the website the pdf was hosted on.

I basically just stumbled across it .

I've been looking for it ever since

[BongoBennie]

One super common practice among the fast crowd is installing a2 heads on k24a4s etc. I'm wondering about doing the opposite and running the K20a3 head (quench pads and .7 bump in cr) on a k24 which would be counterintuitive for speed but would it help out in the efficiency dept, not to mention how cheap these parts are compared to the "real stuff"

[BongoBennie]

***Back from the dead***

So I had a good chat with one of my smartest car buds since this Turbo truck K series Insight thing is starting to collect parts. I just acquired an Element AWD 5 speed, will be running 28" Yokohama 003 mud terrain tires and towing a teardrop trailer.

We talked about the motor and fuel .... 2 10 gal tanks so I can blend E85 and if I can hit 40 MPG that's an 800 mile range on one fillup.... perfect.


All that being said He thinks the only reason the Accord ever got better mileage than the Civic Si or RSX base was due to gearing. A3 head is basically the same port design as all the other K series heads but with smaller more restrictive ports, A3, A4, A8 etc also flow less due to the valvetrain design. A2 Heads have big ports AND big cams since the have the 3 lobe "true VTEC" design" A2 and a3 blocks also allow for the 50° VTC vs the 25° in the K24s. (You can go 45° safely in a K24 before piston contact is possible)

Another thing he said is the oil squirter do in fact squirt at about 20psi which isnt much past idle and would be very good to have. A3 head is also good to 7800rpm valvetrain wise. My goal ultimately will be a car that gets 40 mpg, makes 400HP on straight e85 and will run OK on straight pump gas when necessary, possibly staging injectors for bi fuel use. Engine would be Stock TypeS K20a2 bottom w/K20a3 head 11.7:1 CR , Borg Warner Turbo.......... I've put a few hours back into this subject and it keeps bringing me back to this thread so I figured Id wake it up.

[Ecky]

Next week I'll likely start with my tuning. I'd love to have a discussion on how to best lean out a K series motor.

My build has worked out to:
-JDM K24A2 (K24A), 05 with 08 intake cam
-K20A2 oil pump - no countershafts for reduced weight and friction
-50 degree VTC mechanically limited to 40 degrees, since my engine is an 05 with 06-08 cams - the reliefs for the valves are smaller in the Pistons
-10lb flywheel
-TSX magnesium transmission for weight savings - NOT recommended for turbo since it's more fragile
-3.4 final drive (custom)
-0.647 6th gear from a '12+ Civic Si
-Honda OEM LSD
-RSX ECU with KPro

[BongoBennie]

That would be awesome, Ill be subscribed for sure



one of the other ideas we talked about was the A3 head on the K24a2 block. Keep in mind I have no illusion the turbo is not going to help me achieve MPG anything, it's the Dr Jekyll Mr Hyde of the whole thing.

[Ecky]

I haven't cracked the motor to look, but is it a safe assumption that there's no possibility of any Atkinson cycle with a K, since they're all interference motors?

[BongoBennie]

Maybe not with stock parts but so many aftermarket ones made for big cams and big valves the sky's the limit. I like Mahle piston as they are 4302 low expansion, not as strong as the masses but more than enough for me. Figuring all that stuff out is above my pay grade though.

[Ecky]

Thoughts on running 0w20 in a K24A2? To my knowledge all of the 160HP K motors run 0w20, while all of the 200HP ones call for 5w30. I believe the engine blocks are the same, compression is slightly higher in the Accord vs TSX and valves after VTEC engagement let more air in at the top of the rev range. No idea if there's any difference in piston rings.

[BongoBennie]

I swapped an 04 K24a2 in my 04 EP3 in 06, put 200K on the car with that engine in it. I liked to run 5-30 but as the miles built (that car saw 7800rpm daily) It went up to bat mobile smokescreen status and I was running 10-30 plus additives. Finally took car off road and sold the only car I ever bought new

K24a2 has a crank that is more sought after than all others (not sure why), all are forged
K24a2 has thicker rods, "a2 valvetrain" higher compression all in the piston, piston oil squirters, slightly higher capacity oil pump with balance shafts. Blocks same as Accord, combustion chamber same.

The Accord/Element/CRV/RSXbase/Ep3 all have the same cam lift/duration and are swappable as OEM as far as specs go.




K20a2 head is superior but all can be made to work.
06-08 K24a2 Cams are the most sought after cam for the A2 head, put it on your Accord block with TSX pistons and RSX oil pump and you have your modern day K frank or what ever its called. Fairly cheap speed



K20a3 is only good for jokes..... and scrap collectors like me