Black_6spd

Comparing these two motors against each other performance-wise gives one perspective on where Honda engineers had prioritized performance in the K24A2. During it's reign, the H-motor was Honda's displacement king for it's performance cars outside of the NSX.

Let's look at the H22a's specs for the JDM 97-98 Prelude Type S:
Horsepower: 220 @ 6800 RPM
Torque: 163 @ 5500 RPM
Redline: 7200 RPM
Compression Ratio: 10.6:1
HP / L: 100

Keep in mind that this motor was designed in the mid-to-late 90's and was still able to put down impressive numbers like these. After almost 10 years of design advancements, a sibling with similar design goals was developed with the K24A2.

To compensate for the new SAE HP ratings and emission requirements in the U.S., I've adjusted the HP fiigure for the TSX and used MY2006.
Horsepower: 220 @ 6800 RPM
Torque: 166 @ 4500 RPM
Compression Ratio: 10.5:1
HP / L: 92

So, how does the K24A2 stack up?

Performance: H22a - The prelude has better gearing, a better suited vtec transition, and has more power per liter. Additionally, the LSD comes in handy during cornering and launching. In stock form, it's very easy to upshift and land RPMs back on the big cam.
Everyday driving: K24A2 - Although the total torque figure is only greater by 3 foot-pounds, the difference is far greater. The torque in the TSX is retained almost throughout the entire rev band, unlike the H22A counterpart where it must be revved higher.

Conclusion
If Honda wanted to build a high RPM screaming performance monster, they would have. After comparing these two motors, it's becoming more evident that Honda tried hard to answer the frequent critisism of lack of low-end torque without giving into a higher displacement V6. Since Honda knows their core competency is highly efficient I-4's, they wanted to stick to their guns. In the end, their quest for a better suited everyday driver was accomplished at the price of the high RPM fun we're acustomed to with the early B and F series motors. The first time I revved up the TSX in stock form, I was very dissapointed.

Oh well, I guess you can't have your torque and eat it, too....

ianS

Yes, the K24A3 dun have that vtec punch as the H22a on my old prelude but due to the heavy weight of TSX the K24A3 is more appropriate. You dun want your TSX got out run by a corolla from a stop, right? Well, neway I love both my TSX & and old lude just learn to love both charateristic.

paranode

My head hurts.

username

So the Prelude SH in N America was detuned? Was this because of emissions, or just because we get screwed?

MrChad

Prelude H22 power = TSX K24 power in the real world.

Ask Moda_way how many times he's spanked my our buddies USDM '00 Lude that's bone stock.

The Lude was no slouch, even today without the great iVtec cams. It just pollutes more then Honda would like anyone to believe. That's why it got canned it wasn't ULEV.

GSGOMEZ

H22A is about 100 lbs more than K24A3.

S14 n Tsx

hmmm.

moda_way

I've posted about it before. Our buddy's Lude and I have raced a few times and both being relatively stock, he couldn't pull on me and I wasn't catching him. It was DEAD even.

jpt

The TSX ain't ULEV either...

dom

Any truth to the H22 burning excessive amounts of oil? I mean More than any other Vtec engine.

moda_way

Yes, 00Prelude00 does burn some amount of oil, but only if he kicks VTEC a lot. This motor had the oil sprayers at the bottom of the pistons, pointed upward.

aaronng

Does the K24A2 have oil jets under the pistons too?

moda_way

Nope.

STL

Looking at dynos comparisons, it appears they addressed your disappointment a bit in the '06 models by giving VTEC more of a punch.

JTso

iTrader: (2)

I believe so. I have posted a pic of the engine internal on the forum. Just need to find it...

Edit: here is the post mentioning about the oil jet. I still need to find the pic. https://acurazine.com/forums/showthread.php?t=4489

h1coupe

wouldn´t the k20a jdm engine be a better engine to compare to the h22a?

moda_way

I stand corrected. There are oil jets on our motors. I never spotted them in the Helm's manual and I intentionally looked for them.

Blazin Si

It's a shame the H22 never got as big a following as the B series motors did. The head flows so much better than the B series, plus it has a better designed valvetrain. Too bad they have cable trannies and the ATTS was never a big hit on the Type SH.

The TSX needs a Type S head to really wake it up.

As far as oil burning goes, it seems to be pretty common with B and H series engines. My B18C burned about a quart of oil a week when I first swapped it in my hatch and still does a little bit after the rebuild. Everyone I know at the track uses oil, but we tend to run our cars pretty hard.

GSGOMEZ

Hey I am thinking about getting H22A engine for my 94 accord because accord has about 166 thousand mileage right now and need to replace the engine pretty soon.

amanhao

I think if you guys could try out ABA-CL7 (JDM Accord euro R), you guys would have diferent opinion, and not say the car has no torque, or slow.... I know u guys talking about K24A2, but, its just my thoughts....
Simple Spec:
Horses: 162kW［220PS］/8,000rpm
Torque: 206N・m［21.0kg・m］/6,000rpm
Six speed manual transmission.

This thing its good

Black_6spd

Although they did improve some things under the curve as well as peak-wise, I think it was the way the B-series motor gave the torque AND horsepower up top. Being accustomed to that added "kick" up top, my butt dyno immediately expected the same power curve when jumping in my first K-series.

Even with the 2006, the VTEC transistion is still too high. I still haven't heard or read any satisfactory explaination why the crossover is at 6200 RPM.

Now, I've fixed these so-called "problems" associated with the K24A2's curve with headers, CAI, and hondata.

JTso

iTrader: (2)

Found it! It's in the engine lubrication section.

moda_way

^^ yeah I looked up the parts for that area. I can't believe I missed it in my Helms especially since I specifically went looking for it.

vwong

Oh yeah. My Prelude burns a quart of oil every 1000-1500 miles.

Just for comparison, I have dyno'd both my Prelude and TSX. My H22 has been rebuilt with JDM TypeS pistons and cams, and the head has been ported. It's probably not exactly to the JDM TypeS H22 specifications, but it may be close. My TSX has Hondata reflash and it is the 04 model.

Black_6spd

Thanks for the dynos. Just as expected, the TSX has more power down low, especially between 4k-5k. It was really designed to be more of an everyday driver.

I'm really surprised to see the torque curve that flat for the H22A -- I always thought is was more similar to a B-series torque curve.

Black_6spd

:ibJTsofindsanotherdesginflawandmakesanothermod:

STL

I totally agree!! Having only about 1k of VTEC seems rather silly.

How have those mods affected your gas milage?

jpt

Need to replace an engine at 166k miles? You been putting sugar in the gas tank or something?

ianS

Yup! what's wrong with that engine? it is still new!

Black_6spd

I actually think my mileage got better. I'm basing this on the fact that I drive the car much harder now and still end up with 320-350 miles on the odometer before the gas light turns on.

sauceman

Great thread BTW.

Dem1K

iTrader: (1)

is it auto or stick?

btw nice thread

rmpage

Excellent post.

I would add that the VTEC "kick" people mention is absent on the K series because VTC angle varies across the rev range to keep torque delivery consistent. An i-VTEC engine that is properly tuned will not have a kick at all - the only indication of high cam will be a change in induction noise. The VTEC kick, while fun, is the result of a more primitive engine design.

The TSX K24A2 has the exact same head as the K20A2 in the RSX-S. The entire engine is identically a K20A2 that has been stroked a small amount. Such makes increasing power in the last ~1000 RPM of the rev range difficult without some form of forced induction, as you have a 2.4L engine trying to breathe through a head designed for a 2.0L.

Black_6spd

The adjustment of the VTC angle actually improves the "fun" for me by reducing the low-RPM lag generally associated with a high-revving 4-banger. I think the lack of "kick" for the K24A2/A3 motor comes more from the fact that the torque drops considerably after 7000 RPM.

Although Hondata's studies found (2) factors, I wonder which one is holding back the TSX's top-end potential more than the other:
1. R/S ratio
2. Cylinder filling

I'm interested to know what the tradeoff would have been if we had a better-suited R/S ratio for more track-like conditions? How much would come at the cost of low-end torque? For some reason, I envisioned an early prototype version where the K24A2 had an R/S ratio that gave it peak power at 7800 RPM and the designers realized that it had to be better suited for "american" expectations of V6-like torque down low. Who knows.

Before anyone tells me the old, "FI is an excellent solution to #2", I'm wondering if #2 would be solved by simply improving the R/S ratio. The shorter stroke would result in less tangental forces at high RPM and slower piston speeds. I have a feeling cylinder charging is not an issue anymore with an improved R/S ratio, a long tube header, bigger TB, and ECU tuning.

honda_inspire99

Mostly every vtec motor burns oil especially the B series and H series motors...K24 has more potential when it comes to all motor setups but stock for stock they are about the same. My freind is currently building a k24 block with k20 type R head which will e capable of about 250 whp with a good head, proper tune, and fuel management.
what the k24 is capable of
http://honda-tech.com/zerothread?id=1230331

Black_6spd

Great stuff!!!


http://www.theksource.com/news/04/19...d-dyno-results

I wonder how feasible it is to use the K20A LSD tranny on the TSX? Man, this stuff is confirming all of my suspicions on the K24AX! Man, I bought the right car.

moda_way

I'd eat his lunch if it was an auto.

Is there still an auto lude running? Those things ate auto trannies up.