I have been reading for weeks, and I am not finding a whole lot of difference in the 2. However, I want to make sure I am purchasing the best motor for a frank build.
I understand that there is a lot of different things I am going to have to do to either motor, for my end goal.
What, in your opinion, would be the best block to go with, or are the differences that negligible?
My ultimate goal is 270-280 on 93 octane, will primarily be driven on street only. Just want something NA, that I can have some fun driving to work. I pass a lot of people on the back roads.
Or should I even do a frank build, and just go NA with one of these k24 motors? (both come with head as well. The A2 is RBB)
I will continue to do my homework, but figured I would ask for some input as well. If there are any threads that you recommend I check out, I am always willing to do so.
Here are the 2 motors

JDM Honda K24A Engine RBB Acura TSX K24A2 iVTEC Honda 2.4 200HP 3 Lobe VTEC #7 | eBay

Find many great new & used options and get the best deals for JDM Honda K24A Engine RBB Acura TSX K24A2 iVTEC Honda 2.4 200HP 3 Lobe VTEC #7 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

JDM K24A MOTOR 2008 2009 2010 2011 2012 HONDA ACCORD 2.4L I-VTEC K24A ENGINE | eBay

Find many great new & used options and get the best deals for JDM K24A MOTOR 2008 2009 2010 2011 2012 HONDA ACCORD 2.4L I-VTEC K24A ENGINE at the best online prices at eBay! Free shipping for many products!

www.ebay.com

The 08-12 accord motor will take more effort to use in a swap chassis. What car are you putting the engine in ?

 

99-2000 EM1 (hopefully)
Or worst case an EK coupe
I also just stalked your build. Same state here!

 

For that swap, you want a 2008 or older K24A/A2/A3. The 09 and newer K24 can be used too, but some minor differences such as brackets, crank sensor, exhaust, etc make it more difficult.

09 and newer K24's just aren't as good for a performance build anyways due to the integrated exhaust manifold, head design, VTEC only on the intake cam, etc. But if you are using a K20 head anyways, the 09+ TSX bottom end does have 2 small advantages: higher compression ratio (11:1 vs 10.5:1) and a much more convenient oil filter location.

The 06-08 K24A2 is widely considered the best K series engine since, compared the K24A, K24A3, and pre 05 K24A2, it has stronger and lighter rods, updated pistons for more valve clearance, 1mm larger intake valves, improved intake cam, etc.

I have wondered about whether the head swap is worth it on a K24A2, but I haven't been able to find any dyno comparisons where the head itself is the only variable (although I haven't looked extensively).

 

For that swap, you want a 2008 or older K24A/A2/A3. The 09 and newer K24 can be used too, but some minor differences such as brackets, crank sensor, exhaust, etc make it more difficult.

09 and newer K24's just aren't as good for a performance build anyways due to the integrated exhaust manifold, head design, VTEC only on the intake cam, etc. But if you are using a K20 head anyways, the 09+ TSX bottom end does have 2 small advantages: higher compression ratio (11:1 vs 10.5:1) and a much more convenient oil filter location.

The 06-08 K24A2 is widely considered the best K series engine since, compared the K24A, K24A3, and pre 05 K24A2, it has stronger and lighter rods, updated pistons for more valve clearance, 1mm larger intake valves, improved intake cam, etc.

I have wondered about whether the head swap is worth it on a K24A2, but I haven't been able to find any dyno comparisons where the head itself is the only variable (although I haven't looked extensively).

Thank you for your insight. Greatly appreciated. I haven't found much on the head swap on that specific block as far as performance differences. So, might just save a few bucks and do a full k24A2 w/RBB. It's nearly impossible to find a bare block. And if I am going to order form ebay, it's gonna have the head anyhow.

 

I’ve also been wondering if a rbc or prb head is worth it. I just ordered a k24a (04-05 tsx) and my power goals are pretty small conspired to a lot of people but from what I’ve read it seems like a head swap would pick up 20 or so hp in and of itself. The k24a is a rbb as well right?

 

The rRBB k24a is the 3 lobe performance model. Mine with just an RBC/70 mm and RCREW header 3” exhaust hit 100% on the oem injectors at 6600 rpm first time around tuning 😅 the engine is plenty powerful and has a great torque curve with the tsx head. I am putting a prb head on my built motor but for driving around on the street the full k24a with 50vtc and type s oil pump is about as good as it needs to be. I don’t think you would see 20 whp on oem
Cams from swapping head alone. On a high comp cammed engine with a large manifold I would expect about 20 whp from going RBB-PRB head swap.

 

Agreed, my stock JDM K24A makes great power too. The only mods it has is an 06-08 intake cam, RSX oil pump, OEM oil cooler, OEM block heater, and Accord cable throttle body since the electronic one wouldn't work for my application. Other than a header and exhaust that will work in my chassis, I don't plan on any more significant engine mods. For my application (daily driver), the smooth, linear powerband, OEM reliability, and great fuel efficiency are more valuable than a few more peak horsepower.

I wouldn't expect a gain of 20-30 HP just from swapping the head either, that's like the gain someone would get from swapping a true 3 lobe VTEC head onto a base bottom end. And any gains at high RPMs will be at the expense of power/efficiency at lower RPMs, which may or may be worth the tradeoff to the OP. The design of the K20 head isn't "better", it's just different for a different application.

 

I have a dyno runs with just the cylinder head swap on a K24A2. I should be noted that on the original run the room temp was 60 degrees, on the K20A2's runs it was 102.

Official: Dyno Chart Comparison & Calibration Registry

The point of this thread is to compare dyno tuned charts to compare low, mid and top end gains to benefit helping us all understand where power was made and using what mods. if you would like to share tuned calibrations to benefit others understand what different settings affect different...

www.k20a.org

 

I have a dyno runs with just the cylinder head swap on a K24A2. I should be noted that on the original run the room temp was 60 degrees, on the K20A2's runs it was 102.

Official: Dyno Chart Comparison & Calibration Registry

The point of this thread is to compare dyno tuned charts to compare low, mid and top end gains to benefit helping us all understand where power was made and using what mods. if you would like to share tuned calibrations to benefit others understand what different settings affect different...

www.k20a.org

Sweet, thanks for sharing! That's the first and only dyno comparison I've seen where only the head was changed. What RPM range was that dyno run? And I assume the dyno is SAE corrected for the difference an ambient temperature?

 

That's a huuuge port on both sides. Do you run a 106 mm stroke? I wouldn't use it on a 99 mm engine, these ports need huge air flow to get in an efficient range. Drag applications would may utilize it. What is your engine setup and application?