K20a vs K24A2

[Karlo]

When I look at the two different K motors I am wondering if the K24 would be worth buying instead of the K20a. The torque on the K24 come on a lot sooner than the K20a, that seems to have some weight to me. :lift:

See PDF file below for the Supercharged K24!!

K20a

2007- Honda Civic Type-R (FD2)
Displacement: 1998 cc
Compression: 11.7:1
Power: 222 bhp (225 PS, 165 kW) @ 8000 rpm
Torque: 159 ft·lbf (215 N·m) @ 6100 rpm
Redline: 8400 rpm

K24A2

2004-2008 Acura TSX
Displacement: 2354 cc
Bore and Stroke: 87 mm x 99 mm (3.43x3.90 inches)
Compression: 10.5:1
Power: 200 hp (147 kW) @ 6800 rpm (2004-2005)
Power: 205 hp (150 kW) @ 6800 rpm (2006-2007) *SAE Net Rev 8/04
Torque: 166 ft·lbf (225 N·m) @ 4500 rpm (2004-2005)
Torque: 164 ft·lbf (222 N·m) @ 4500 rpm (2006-2007)*SAE Net Rev 8/04
VTEC Engagement: 6000 RPM
Redline: 7100 rpm

[Karlo]

Gage what modification are you doing to your K24a2?

[Gage]

Gage what modification are you doing to your K24a2?

Frankly I'm asking lots of question, getting advice, and still trying to learn what the options are. My goal is to start with is about 220whp - 230whp with a red line around 7800 rpms give or take a few hundred rpm. I believe from what I've seen others doing that my goal is realistic.

My list so far includes:

Kpro tuning software loaded onto a compatible ECU, tuning the engine to make maximum power.
Modified TDC senser.
Proven aftermarket cams
DC5 RBC intake manifold.
Custom built header.
No Cat.
High flow muffler. Got tired of ear plugs under high accelleration in the Atom.
With that said, a helmet eliminates the need for ear plugs.

When everything is paid for, I would like to Install a (not yet available stateside) Rotrex Supercharger.. which produces less heat and stress on an engine than a typical supercharger or turbo setup. Low boost on a Rotrex could produce 300whp without danger of damaging the stock short block. I'm told that would be a very conservative goal.

I hope someone does all this before I do so I can benefit from your example. =0)

[Karlo]

"From an engineering standpoint I don't much care for any of the K24's because of the excessively long stroke and crappy rod/stroke ratio.
To be right an engine with a 99 mm stroke had better have a bore of about 105 mm or I have to consider it to be a tractor motor, and not really what you want for high performance use because of the limited rpm potential. Also, all K24's have a counter-rotating balance shaft assembly inside the oil pan, we call it the 'egg-beater', and that completely precludes baffling the oil pan properly. Baffling the oil pan is absolutely necessary if you expect these engines to live under higher than stock Honda sedan cornering loads. This is something I dealt with immediately because I'm using them in Elise's. If you install one of these engines in a car that'll do better than about a .8 G around a corner you'll be guaranteeing the engine's death due to oil starvation.

For 'large' displacement I build a 2,308cc "K23A" that quite happily revs to 9,000 rpm."

Quote from Joe McCarthy

[aloysius]

If you replace the k24 oil pump with a k20a2 you get to remove the balance shafts and you also can use a k20a2 windage tray to help control the oil. There is a small protrusion on the k20a2 oil pump that needs to be machined off.
check out this thread:

http://honda-tech.com/zerothread?id=2216448

[Gage]

Also in response to the information posted by Karlo:

From Jeremyinlinepro at k20a.org:

"I thought I would share this information instead of keeping it to myself to show that with the proper tuning and proper engine building the K20a bearings work fine in race applications. These pictures are from the tear down of my 310whp 10.93 comp4 car.

This k24 engine has 1 race from last year on it which we went to the semi's, 1 misshift to over 11,500(my fault last year), 80 plus dyno passes, 4 events from this year which we went to the finals each event and ran all of the qualifying which is at least 5-6 full passes per event. We shift this car between 10,300rpm-10,500rpm and have shifted it as high as 10,800rpm. It has a stock OEM K20a2 oil pump unmodified(no stiffer spring or s2000 parts). It is a 100% stock k24 99mm crankshaft with a rod ratio in the 1.5's. The bearings are OEM honda k20a bearings. The pistons weigh over 330g and the rods weigh about 500g.

This motor is apart to re-ring and re-bearing it. It did not have any failure. So if someone every says that you can not use the k20a bearings because they are too thin and they will spin you should think twice about what they really know because here is solid proof that is untrue."

More quotes:
"So for those that do daily driving and the occasional road course, an oil baffle is going to be important for proper oiling. Good to know another thing to buy but to protect the engine."

"oil pan baffles can never hurt. However they are only really required for cars that see track (roadcourse style) time. Some road courses have some very long sweeping turns that can cause the oil to slosh to one side of the pan which leads to oil starvation. You can watch the oil pressure drop if you have an oil pressure gauge.

This is one of the reasons that people switch to dry sumps or run www.accusump.com .

No one should be doing anything on the street that requires a baffled pan"

[Gage]

More quoted information:

"On the topic of World Challenge, funny coincidence...

I was recently out of town tuning a privateer world challenge touring Honda running a K24. This particular team had experienced 4 engine failures the previous year on their K20 engines, and had decided to take the weight hit and go up to the K24 setup. Now, the K24 doesn't produce much more (if any) power because it uses the same throttle body and cams and head (in WC Touring). But, you generally make peak power at a lower rpm and the K24 is limited to 8000 rpm by the rules.

This is the reason, I think, that the K24 is more successful. The torque is offset by the weight increase required (and handling suffers too because of the weight), but longevity is much better - because engine speeds are kept lower, not because the K24 is stronger. Guys like Derek from Hondata have figured out how to make a powerful K20 combo survive at high revs now, but it took him a couple years and several engines. We'll see if that knowledge gets passed on to some of the WC guys and they go back to a K20 setup with less weight."