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K20A2 vs K20Z1?

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110K views 29 replies 15 participants last post by  04rsx-s  
#1 ·
Can someone tell me what the REAL difference is between the K20A2 and the K20Z1 from the two different generation RSX Type S? Would it be better to get an RSX with the K20A2 or an RSX with the K20Z1, and why? All I see in the specs is a difference of 1HP and 2FT/LB Torque. Why would honda change the engine for such a minor difference in numbers?

Thanks:cool:
 
#5 ·
Re: K20A vs K20Z1?

the tsx head is rbc ready, but I bet you were aware of that already! :p
 
#19 ·
Re: K20A vs K20Z1?

ELFATHER said:
the difference between the a2 and z1 are the cams and trans a2 its 4.4 and z1 its 4.7.
obviously the best motor will be the one with more hp =k20Z1 210HP. BUT its a lil more complicated to swap the z1 than the A2 due to the VSS bullshit.
Click to expand...
The VSS BS can be avoided by using a tranny from something an 02-04 RSX or other low frequency VSS, I might add.

I'd go for the K20Z1 head because of the better cams and lower mileage given your choice. But in my particular case, I went with the K20Z3. I'm swapping out the cams anyway. Just bought 2 sets of Toruku cams! One for my RSX-S (02-04) and one for my Del Sol (K20Z3 engine and tranny).
 
T
#13 ·
all a matter of opinion i guess cause they say there is the final drive difference but i only saw a gain of about 2 horsepower and it looses 2 ft lbs of torque. I dont know i have the a2 in my 04 and i beat an 06 with the same upgrades. In a race with the two cars in my opinion it would come down to driver skill not the motor or the gearing.
 
#14 ·
The only real difference engine wise between the A2 and Z1, is that the Z1 gets PRC cams. I had thought that I heard there was also a TB issue as well with the Z1(could be wrong). The Z1 ECU requires a seperate adaptor for Kpro.
 
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#16 ·
yes they are prc cams..but they're a toned down version. they're not as aggressive as the prc cams that come in the k20a.
the part numbers differ.
this information was provided by hondata. i'd search for the link but i'm lazy man..haha

k20z1 gets
better mild version of prc cams
better/higher final drive which shortens gearing
 
#21 ·
not drive by wire
 
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#24 ·
Re: K20A vs K20Z1?

The S2K and RSX tires are the best for my application. :) I don't have to adjust anything. The S2000 and RSX tires are the same diameter and is what the VSS on the K-series transmissions are set up for.

Plus, you still got a bit of meat even with 17" and the wheel well is filled in really nicely.

As for the ECU, I will get the low frequency VSS signal from the S2000 cluster. That part will be wired to everyone else's VSS IN on their clusters because my low frequency line doesn't have any signal in it and it still goes to the VSS IN on the ECU. I just have to move the VSS wire from the VSS to ECU A connector to some new line I'll add that's dedicated to high frequency VSS (to the S2000 gauge cluster). This way my cruise control and other functions will still work.

Also, there's the ECU's constant speed signal setting if that fails so can retain VTEC that way. :)
 
#25 ·
Re: K20A vs K20Z1?

I'll try to explain things in a bit more detail...

The S2000 has both high and low frequency VSS lines. Some systems are still using an older style VSS signal and is the reason for the two lines. It's converted in the cluster here.

The 05-06 RSX has both high and low frequency lines as well. The high frequency VSS only goes to the ECU where it is converted to low frequency for all the other systems requiring a speed signal.

In my Del Sol, there is only a low frequency VSS line. It runs from the VSS to the ECU, gauge cluster, cruise control and possibly one other system. This is the case whether or not a K-series swap is involved.

When you remove the low frequency VSS, those systems are still inter-connected but not getting a signal. The signal can be introduced anywhere the low frequency VSS line is routed to.

With my S2000 cluster, it no longer requires a low frequency VSS signal but can supply one. The old VSS IN for the cluster becomes the new VSS OUT and the signal is now carried to the ECU, cruise control and so on.

The S2000 cluster is capable of putting out a low frequency VSS signal by converting a high frequency VSS signal to low frequency. This high frequency VSS signal is provided by the K20Z1/Z3 VSS to the S2000 cluster through a dedicated high frequency line connected to nothing else.
 
#28 ·
Well, the 17s won't look like most other 17s on most Civics because I'll have a fatter tire. I personally like 16s on most EG/DC2s. Nice amount of meat and not too showy.

I've got 06+ EX wheels for my Del Sol (after 5 lug swap) so I'll look kinda stock. :) But I'd like to slap on my RSX wheels if I want to be a little showy.
 
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