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86 CRX SI K24a swap

7731 Views 189 Replies 9 Participants Last post by  cspcrx
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Been working with HASport for over two years building a mount kit for the 84-87 CRX/Civic. They are finally done so off to swap we go. All loaded up and heading to HASport to document the swap!

Untitled by Victor M, on Flickr

Back story on the car. I purchased it in 1992 as my daily and daily drove it until 2002. I started racing it in SCCA Solo2 events in 1994. In 1998 HASport was just starting out and contacted me about swapping my car to a B16 for Sport Compact Car Magazine. going from a 100whp 1.5L single cam to a 150whp 1.6L twin cam was a huge power change.

A few years later stared participating in NASA HPDE and time attack events. First event out came in 3rd place, not to bad. This was at an event held at Phoenix International Raceway.

MayPIR_zpsb556d3be by Victor M, on Flickr
5FAA8FF3-D28D-48F3-9D7E-5BF7C7703A81_zpslbkp7c0f by Victor M, on Flickr

After a few years I realized while being classed by power to weight the low torque of the B16 was not helping me. I needed more displacement so I started speaking with my friends at HASport about a B18C swap when Brian said let’s just K swap it. So because the process of developing the mount kit and sourcing parts.

Big parts going in are a JDM K24a 3 lobe and JDM RSX 5 speed. Motor will be kept stock with RBB manifold but there are a few upgrades. Manifold and Accord 60mm cable TB were sent to King Motorsports to be opened up to 64mm. Have 50 deg VTC, 4 Piston Type S oil pump and Unit 2 baffled oil pan. Trans got a KAAZ. 1.5 LSD. Using a Hybrid Racing no cut shifter box and cables. K tuned header and some other parts.

in prep for the upgrade in power i had to move up from the 15x7 with 205s that I have used for years. New setup is 15x9 245s up front and 15x8 225s in the rear. Also upgraded to a Fast Brakes 11” rotor with Wilwood calipers and Hawk pads.

Untitled by Victor M, on Flickr

we started pulling the B16 out Wednesday and will wrap it up this Saturday. Plan is to also prep for the K swap this Saturday as well. Then the following week put the motor in.
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Congrats on the build man! Just finished the last VA vid. That's gonna be one helluva fun car! Keep us posted on the tuning/dyno. In for pics of your readout screens and setup

Sidenote: I was considering innovative or hard race mounts but I had to support the boys! Tell Brian I said thanks! Lol
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Next Saturday is Dyno day, will get some video and pics for sure. We are also going to scale the car so we know what we are shooting for, trying to get as close as possible to the 10:1 power to weight ratio.

nice choice on the HASport mounts! Hope your project goes well!
Finally hit the scales and the dyno. Not sure we have the exact same amount of fuel in the car but it appears the car is 25lbs heavier. goal was to get to a 10:1 power to weight ratio, with driver, and we did it. 220 wheel hp and 200 ft lbs.

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Thanks for sharing that view of the result too. Gives a much easier overview, as it is more common having torque and power scaled the same and both in one graph. The flat out beyond 5800 rpm will be definitely feel-able.
I did run some modeling of the shifts and shifting 7200 2-3 lands right at peak TQ. All other up shifts will be at 7000 and do the same. That’s one positive of all of this. We will see as soon as it hit the track how usable it is. On the street it’s a monster compared to the B16a that was in it before.
I did run some modeling of the shifts and shifting 7200 2-3 lands right at peak TQ. All other up shifts will be at 7000 and do the same.
That are really good news.

On the street it’s a monster compared to the B16a that was in it before.
I can imagine this, sounds pretty good. On track the higher gears in WOT load will tell you if it still fits your season aim. At least shift-torque connection fits. From my experience with my race teams I know these guys prefer a constant or rising torque, especially at higher gears, as it gives an easier control and less shift events, what makes racing a bit easier and your ride a bit more competitive.
Totally agree! I would like the TQ curve to be flatter. Tuner really feels RBC would be a good upgrade to help with this. He said since I have the 50 VTC it won’t drop a lot of TQ but would widen the power band and help maintain it. Need to get some measurements to see if it would fit. Read lots of posts on RBC and RRC for the K24. Seems there a lot of debate. Especially on a basically stock motor on stock cams.

here is a dyno pull from my B16a for comparison. Night and day difference!

Untitled by Victor M, on Flickr
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Tuner really feels RBC would be a good upgrade to help with this.
I wouldn't agree to that. The 2nd order resonance of the RBB IM is at 7700 rpm, that of the RBC is out of scope on that engine. You will likely loose up to 10 wftlb from 4000 to 6000 rpm. Beyond 6500 rpm the RBC will likely gain some wftlb, but my assumption it is not worth the money. The limiters are somewhere else: cams and port at least. Against a 2nd order harmonic in a distance of 700 rpm the weak RBC won't have much to add. My bet 5 whp peak power more for a way bigger loss from 4000-6000 rpm. The power add just comes from the fact the RBC can carry the torque more far to the right hand side. Would you mind to share the calibration and WOT log of the engine for a 2nd view? I am just curious where the waterfall at around 7200 rpm comes from.
here is a dyno pull from my B16a for comparison. Night and day difference!
Yeah, indeed. Was the lambda plot on the sheet the one of the tail pipe? The quality shows huge potential for improvement, the quantity would maybe indicate a leakage of the CAT-back, as it is way too lean. Same tuner?
I was just sharing the B16 plat as a comparison of where I was and where I am now with the K24. Not a comparison of tune or overall shape of curve. The B16 graph was from a long time ago, dont recall how AFR was capture. My guess is at the tail pipe.
I was just sharing the B16 plat as a comparison of where I was and where I am now with the K24. Not a comparison of tune or overall shape of curve. The B16 graph was from a long time ago, dont recall how AFR was capture. My guess is at the tail pipe.
If you see that stuff on a daily basis with great interest, you see it everywhere ;). I know it was only for comparison of the torque/power level. After 20 h of driving you might think about the next step. Humans are so adaptively.
I hear you there. I have enough power turns into my car feels slow as you get accustomed to it. For me i can’t be over 220 due to class rules. I can always detune, as many do to improve overall curve performance but limit peak HP to meet class rules.
I can always detune, as many do to improve overall curve performance but limit peak HP to meet class rules.
You made a precision landing or is it already detuned?
tuner walked it up to that number. It’s great it worked out, same with my B16a, it made just the right amount for the class.
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little work on buttoning things up this weekend. Picked up a VTEC oil pressure switch in the junkyard. The JDM motors don’t have them, just a bolt screwed in to plug the hole. I wanted one so there would be one more layer of protection and an indicator of low oil pressure. Easy install and just need to turn it on now in the software.

also installed the red valve cover. Always wanted one on my B series, never did it so I said why the heck not. I think it adds some extra HP too LOL!

Untitled by Victor M, on Flickr

cross brace back in place so it’s all buttoned up in the engine bay. We are going to try and get together Thursday and do a final video to close things out.

still need to pull the left front shock, which during the swap we discovered the compression adjuster was messed up and not working. Made it a pain when we were putting axles in and out! Local place rebuilds Koni shocks so need to pull it and get it done. Hoping to make a local track event end of April!
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Hoping to make a local track event end of April!
Good luck for that! Do you any steering behavior, brake characteristics, tyre pressure, ... control run before?
thanks. I have been racing this car since 1994 so I have some idea of how it behaves.

that said I am now running a staggered tire setup, 245s up front and 225s in the back. So I will probably take a little rear sway bar out to make sure it’s not oversteering too much. It’s an open track event hosted by NASA so we get four 20 minute sessions. I am looking at this event as a test and tune more than anything.
Final video in the series and on the build. I will be doing some of my own as I further develop the car.

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