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RBB DIY Instructions for your Kseries engine and DYNO Results on my 07 K24A2

28845 Views 78 Replies 19 Participants Last post by  bsivoljr
For a mild NA build (stock 07 TSX cams) such as mine I think running the RBB is the way to go vs the RBC. The advantage of the RBB is the additional runner length which increases velocity in the head ports which adds more air in the combustion. After 6500 rpms the RBC should show more gains over the RBB since smaller runners create less restriction and more air can find its way in the combustion chamber.

Hondata did some testing with the K24A2 and the RBB and RBC and the results are interesting. http://www.hondata.com/tuning_k24a2_tsx_engine.html

What I found that ultimately made me go with the RBB was that in all the K24A2 dynoes I looked at the RBB beat out the RBC in the low and mid RPM range were it matters for daily driving and didnt loose much on the top end for me to justify loosing the tq and going with the RBC over the RBB for the K24A2. Many have stated that the limited VTC on the K24 made for the low TQ #s of the RBC but Hondata's read in the above link as well as other dynoes where the RBB and RBC were tuned to as much as 45 degrees shows me that there is something to this.

In the end the dyno will have to tell the story for me and I have the RBC on the shelf just in case.

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This DIY is being done on a 07 K24A2 motor in a 2006 RSX Type-S. The head was modified originally to house a JRSC manifold normally fitted for the K20 head so the below DIY will cover mods needed to fit a K20 head.

Some things to note is that the 06-08 RBB manifolds will need the below mods. The 05 and below RBB already have provisions for the IACV so you may prefer that option. Before going out to get the 05 or below RBB keep in mind the 06-08 model are 64mm vs 60 mm size.

Here is some additional info I got from "AllDay" on CRSX. I do not know if the RBB listed below is the 06+ or 05 and below but I assume its the 05 and below because its the easiest to mod and use.

rbb

runner length- 31cm
runner min. width-4.4cm
runner max width-4.8cm
total runner volume- 1970cc
plenum volume-1650cc
total volume-3620cc

rbc

runner length-18.5cm
runner min. width-4.8cm
runner max. width-5.1cm
total runner volume-1080cc
plenum volume-1720cc
total volume-2800cc

Special thanks goes out to "tiger" on CRSX for sending me his pics for his RBB mods he did to help me get an idea of the scope.


Here is the link to the DIY I put together with pictures.

http://www.willbelayforfood.com/rsx/rsxmainsite/RBBDIY.htm

Thank you
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nice write up

GL on your build :thumbsup:
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awesome work man. you're going to end up making me spend money i don't want to spend i can see it now!! lol
very nice work. guess i need a fujita now....fuck
Nice write up
very nice work. guess i need a fujita now....fuck
You should be fine with the Injen CAI as well although I havent tested it.


Thanks guys I appreciate the feedback. :thumbsup:
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longer runners produce a lower frequency resonance of the air intake pulses that better matches lower rpm bands, hence better torque/hp at those lower bands.

shorter runners produce a higher frequency resonance of the air intake pusles, so better torque/hp at higher rpm bands.


http://www.chrysler300club.com/uniq/allaboutrams/ramtheory.htm
Well the question for me was the low end TQ gain of the RBB enough to outway the loss in WHP on top with the RBC? In my case I dont think so. Can I prove it 100%? Not yet but I will. After getting tuned at T1 which I have been going to for years with other projects on this car I came away with 205whp\174tq.

Tony as usual did a wonderful job on the car but we all quickly realized that the car was making what it was going to make with the RBB manifold. You can see from the graph that all the tq was made as expected in the midrange but because it fell so quickly so did peak power. Erik Loza also got tuned that day with his K24 with RBC and stage 1 Toruku cams and has the dyno which shows ours results overlayed and you can clearly see how the RBC puts the power on top.

After some discussions with Tony we all agreed that since I already have the RBC its worth the easy effort to bolt it on and retune since 15+ should be gained on top which is something I could definately feel. I will be putting the RBC manifold on and getting retuned shortly and will post results.



Thomas, here are our respective graphs, over-laid...



I just wanted to say again how much I appreciate that Tony at T1 was able to tune us both on the same day and that you were willing to give the RBB a shot, Thomas. So mamy times, the "gospel" we see is really just apples to oranges and everyone runs with it instead of trying it, themselves. I think we both knew that the RBC would out-perform the RBB on the top but the surprising thingto me is how the torque plots for both our cars were almost identical for most of the range. That is what is special about the K24's: They will make torque, no matter what.

What I am really looking forward to is seeing how your car does with the RBC back on it and the late model TSX cams. Since you have a 50-degree VTEC gear on there, we'll get to see how potential they have on the top end. Thanks again, dude... :beerchug:

Erik
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Good stuff Thomas, that is really too bad that it didn't pan out as we'd all hoped. Thanks for being willing to try something new, as always. Looking forward to your results with the RBC. My '06 K24a2 with a 50 degree VTC, RBC, I/RH/E is going in this weekend, and will be put on the dyno next Wednesday, our results should be similar!
what vtc gear are you running?
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what vtc gear are you running?
50

The midrange is good and the car drives very well but I think now the RBC is a better choice for me. I would also agree the 50 vtc is a must on a K24 with the RBC where as the RBB doesnt care as much. We played with all the higher cam angles and it didnt help.
i see

well i have my new vtc gear here, my new tsx manifold, and some other stuff. lets see what i cook up
Well the question for me was the low end TQ gain of the RBB enough to outway the loss in WHP on top with the RBC? In my case I dont think so. Can I prove it 100%? Not yet but I will. After getting tuned at T1 which I have been going to for years with other projects on this car I came away with 205whp\174tq.

Tony as usual did a wonderful job on the car but we all quickly realized that the car was making what it was going to make with the RBB manifold. You can see from the graph that all the tq was made as expected in the midrange but because it fell so quickly so did peak power. Erik Loza also got tuned that day with his K24 with RBC and stage 1 Toruku cams and has the dyno which shows ours results overlayed and you can clearly see how the RBC puts the power on top.

After some discussions with Tony we all agreed that since I already have the RBC its worth the easy effort to bolt it on and retune since 15+ should be gained on top which is something I could definately feel. I will be putting the RBC manifold on and getting retuned shortly and will post results.



Thomas, here are our respective graphs, over-laid...



I just wanted to say again how much I appreciate that Tony at T1 was able to tune us both on the same day and that you were willing to give the RBB a shot, Thomas. So mamy times, the "gospel" we see is really just apples to oranges and everyone runs with it instead of trying it, themselves. I think we both knew that the RBC would out-perform the RBB on the top but the surprising thingto me is how the torque plots for both our cars were almost identical for most of the range. That is what is special about the K24's: They will make torque, no matter what.

What I am really looking forward to is seeing how your car does with the RBC back on it and the late model TSX cams. Since you have a 50-degree VTEC gear on there, we'll get to see how potential they have on the top end. Thanks again, dude... :beerchug:

Erik
Great power guys, you both used to make that at part throttle :shakehead:

I kid, I kid, nice work and write up as always.
guess i will not be spending that money afterall...thank god
too bad we couldnt see some 1/4 times out of it. im not as big a fan of the dyno as i am on the speed and stuff like that. one reason why i like street tunes over dyno tunes
G
...one reason why i like street tunes over dyno tunes
Well, OK I guess but based on how the torque falls off after 5,000rpm's, I can see no reason why anyone would want a stock TSX manifold over the RBC on their car. Another indicator of how bad that manifold chokes the motor is that despite the fact that Thomas has one of the best headers you can buy on the car and a very free-flowing exhaust, the motor made no more power than a stock TSX engine.

I was right there while Tony was doing the pulls and you could audibly hear his motor struggling to breathe at the top of the pull. It was like it just could not go any farther while the RBC kept climbing.

Tony brought up a really good point after we were comparing results between the two setups: All the parts need to combine to create one harmonious system and if you insert a part into the equation that does not compliment the others, then that becomes your limiting factor. So, while Thomas has a header and exhaust capable of supporting as much power as he can throw at it, when you install a manifold designed to give a 4-door passenger car with a 2.4L motor and automatic transmission a flat torque curve for around-town driving, you will probably get results just like the factory wanted: Stock power.

If that's what someone wants, more power to them bu based on what we saw the other day, there is no reason to use any Honda manifold other than the RBC (or RRC, I guess) on a K24 that you plan to get more than 200hp out of. Just my opinions, of course.
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Well, OK I guess but based on how the torque falls off after 5,000rpm's, I can see no reason why anyone would want a stock TSX manifold over the RBC on their car. Another indicator of how bad that manifold chokes the motor is that despite the fact that Thomas has one of the best headers you can buy on the car and a very free-flowing exhaust, the motor made no more power than a stock TSX engine.

I was right there while Tony was doing the pulls and you could audibly hear his motor struggling to breathe at the top of the pull. It was like it just could not go any farther while the RBC kept climbing.

Tony brought up a really good point after we were comparing results between the two setups: All the parts need to combine to create one harmonious system and if you insert a part into the equation that does not compliment the others, then that becomes your limiting factor. So, while Thomas has a header and exhaust capable of supporting as much power as he can throw at it, when you install a manifold designed to give a 4-door passenger car with a 2.4L motor and automatic transmission a flat torque curve for around-town driving, you will probably get results just like the factory wanted: Stock power.

If that's what someone wants, more power to them bu based on what we saw the other day, there is no reason to use any Honda manifold other than the RBC (or RRC, I guess) on a K24 that you plan to get more than 200hp out of. Just my opinions, of course.
I think that's very true. From the results (and thanks again to all members who were involved), the RBB just becomes a bottle neck. What was most surprising to me is how closely the graphs were to each other in the low to mid range. Which is were all of the argument for the RBB was. Hell, if I didn't have a blower sitting on my work bench I would probably go get an RBC. :eek:
sucks though the rbc manifolded k24 has cams in it, i wanted to see what it does without cams
G
sucks though the rbc manifolded k24 has cams in it, i wanted to see what it does without cams
The cams are very mild: They still use the OEM valvetrain. But you can wait for a while and see what Thomas' results are when he gets re-tuned with the RBC. The plot will probably then look like mine.
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