k24a2 Stock (what's really best?) (VTC/Intake Manifold)

[iDom]

OK, now I have been looking at information for about a year and a half now, and what I am (thinking) is this:

(k-pro, duh)
- k24a2
- 45-50* VTC Actuator
- RBC IM
- JRRH/Test Pipe/HKS Hi-Power

Plans:
I like OEM reliability. So, I don't wanna open the head up and put new cams in, I don't care for that (at least right now)

Questions:
VTC Actuator
I have been reading a lot about this lately, I was originally not even concerned with this, but I see that the benefits of getting a higher degree VTC is worthwhile..
- Just to get things right, the stock VTC on the TSX is 25*, correct?
- Also, I have read on Hondata that they have been experimenting with the VTC actuator out of the RSX-S which is a 50*, right?
- In the reading, I read that a 50* VTC is not "safe" with the k24a2 because of the valve/piston clearance in the event of "over rev'ing/mis-shifting".. They suggest a 45* VTC..
- Question(s): Is this all true? Anyone want to shed some more light on this? And, is there a VTC that is at a 45* from the factory rather than 50* ?

RBC
I have also done a lot of reading about this as well.. From various dyno sheets, all I see is that there is a greater significance in the loss of Torque in the low end with the shorter, fatter runners of the RBC (with just a bit more HP up top) than the longer, thinner runners of the RBB.
- Also, all dyno results I see of stock k24a2's typically only rev out to 7,500 RPM and there is a loss of HP, and a very large loss of Torque at the end. So, that's all the more I plan to rev mine out to.
- I know it is recommended to get the RBC, especially for boosted applications, but for what I want to do, I am wondering if I really should or not..
- Question(s): Anybody want to shed some new light on this in addition to what I have said? I see some good numbers with the PRB. Basically, after a tune, is there going to be significant gain in performance based off of what I want to do between the RBB/RBC/PRB IM's?

[AttarixEp]

The VTC. Most will say 45* including myself, for a safety zone. Some will say go all the way, they've never had issues. I like my safety zone. K-pro is reliable, but accidents happen.

The k24a2 head when compared to the K20a2 head is almost identical. The springs are a little weaker, The high speed lobe is a little smaller. The K24 is built for tq. The k20 is built for top end. Swapping in a full k20a2 valvetrain with TSX cams will yield higher rev limits. However you will need the RSX-S oil pump as well to gain full potential.

With the RBC manifold, get at least a 70mm TB.

[iDom]

Yea I definitely want a 45* but I want to buy it as a 45* rather than 'attempt' to make a 25*/50* a 45*.. Know what I mean?

[AttarixEp]

Through K-pro, it's simple. When you're tuning your timing advance's, you limit it to 45*. It just keeps the gear from rotating the full 50. I opted for that over modding the 25*. Some places I talked to about it were even hesitant to modify the 25* when I asked about it.

[iDom]

Through K-pro, it's simple. When you're tuning your timing advance's, you limit it to 45*. It just keeps the gear from rotating the full 50. I opted for that over modding the 25*. Some places I talked to about it were even hesitant to modify the 25* when I asked about it.

Yea, it would cost me more time/money probably to modify the 25* than the relatively cheap $125 50* actuator.. I usually get OEM parts at a cost discount from a nice guy at a local Honda dealership so maybe it'll be even cheaper too.

[AttarixEp]

Gotta love discounts!

[Ba82Ep3]

Modding the VTC isnt hard. Its a nice chunk of metal to mod, but the Hondata page shows you how to do it. The purpose of modding the 25* to 45* is to have a PHYSICAL stop... not just a programmed stop. I have seen the discussion both ways as well... some say its ok others dont. I ran a modded 25* with my TSX pistons in a k24a1 but in the end i dont feel i needed to.

Also if youre just NA you wont really need to advance to 45* to make power. You could honestly just leave it as is. You wont really be able to unlock the FULL potential of a modded 25* until youre boosted or have opened up your intake and exhaust paths beyond OEM. Also, k24a2 intake ports are closer to k20a2 intake ports... that isnt a bad thing... but there is less OEM flow than the k24a1 head. Something to consider when looking for...

... manifolds... i was really impressed with the versatility of the PRC with a k24. It was definitely better than a PRB. Nice broad powerband from 2.5krpm on up to about 7krpm. I just recently got my hands on an RBC for myself (going to RRC) for more testing... but the few k24a2's i have tuned with an RBC and 25* VTC were dogs compared to a comprably equipped k24a1 with more VTC.

My JRRH literally sat on my exhaust tunnel after my k24 swap. I removed all heat shields looking for clearance and relocated my shift cables... nightmare. Im not saying that is the case with all of them, but i had to bail on the JRRH for my setup. I would really like to see someone on this site score an ASP header for a build like this. $$$

If you want a *50, i have one ill hook ya up with. Just LMK.

[Slip_Angle]

I've done a fair bit of experimentation with the k24a2 and so far here is what I've found worked best.

K24a2 /w 2006 TSX cams. If you have an 06+ motor, you already have them.
KRRH
RRC Intake Manifold - Keep the torque, gain the HP. (vs RBC, RBB, PRC and PRB)
50* VTC (MAX VTC on this setup is 40)
High Flow Cat (test pipes are awful)
CAI (long tube)

[K20A EP3]

Dave you think i will have to worry about piston/valve contact with my set up or are you going to limit it to 45* in the tune?

[Ba82Ep3]

Already got it covered for ya Chris... ; )

[K20A EP3]

appreciate it man. but you think if it were to go to 50 id have a problem? id hate for that to happen and have to redo this again lol

[bchaney]

From what I've read, the RBC and 45/50deg VTC work hand-in-hand. If you get an RBC, you'll need more VTC flexibility to harness it's full potential.

[gtolio]

Anyone have a good thread for which OEM manifolds came in which cars?

It seems like such a simple request, but a search yielded nothing.

[iDom]

What motor mounts were you using that your JRRH wouldn't fit? I was planning on getting some innovative MM when I swapped it in.

Also, what cars come with the RRC and the PRC manifolds?

[iDom]

I've done a fair bit of experimentation with the k24a2 and so far here is what I've found worked best.

K24a2 /w 2006 TSX cams. If you have an 06+ motor, you already have them.
KRRH
RRC Intake Manifold - Keep the torque, gain the HP. (vs RBC, RBB, PRC and PRB)
50* VTC (MAX VTC on this setup is 40)
High Flow Cat (test pipes are awful)
CAI (long tube)

May be a noob question, but why a cat over a test pipe? I always thought that less restriction = win