I've been looking into doing a Mini me swap on my 91 EF Hatch DX. From what I understand I can use one of two heads. The Z6 or the Y8. I want to know what the main differences are in reference to the swap. I know the Z6 is OBD1, so it's pretty easy to wire. I've read that the Y8 is a lot harder because it is OBD2. What is involved in that swap that's different from the Z6? I can't find any cheap Z6 heads, but the Y8 heads are dirt cheap where I am. So I might swap that on if it's not that hard. Also, Are there any significant performance differences or reliability differences between the two?

Thanks for the help!

 

if you really really wanted to
i think the z6 head is better but the the y8 manifold is better
its your call
i dont think you would feel much differnce between them wichever route you go

 

What about install? I heard it's a lot more of a pain going from OBD0 to OBD2. A lot more of a pain than going to OBD1. Which would push me to find a Z6 head

 

you can convert it to obd1
check out rywire.com
and i would never go obd2

 

Sweet, so If I can use OBD1 on the Y8 head, it will be exactly the same as if I were to use a Z6 head. Also, my car is 4-speed manual. What trans can I use to swap it to 5-speed? Sorry for all the dumb questions. I'm coming over here from Toyota world.

 

i believe it is exactly the same
search and confirm that tho
and any d series tranny will work
the si tranny is worth its wieght in gold tho
lol you might feel more of a differnce just doin a si tranny vs the mini
but i would still do them at the same time

 

Thanks a lot for the help. I'll be taking it on soon, and I'm sure I'll have more questions. No matter how many write-ups I read, I still don't understand the electrical portion of the swap!

 

The main thing you should be concerned with when deciding which head to use between the two is how they will effect your compression ratio. That's where the biggest difference will be. Also, there is a difference in which combination of headbolts you'll need if you go with the Y8 head.

 

z6 mini-me swap:
http://crx.honda-perf.org/articles/z6swap/z6swap.html
&
y8 mini-me swap:
http://www.geocities.com/senpai_perf.../a6minime.html

 

No need to convert from OBD0 @ all using either! Y8 = higher compression ratio than Z6 due to smaller combustion chambers. (32.8 vs 34.6) here ya go :
http://www.zealautowerks.com/dseries.html
You CAN however vary CR by using different HG thicknesses as needed (boost no likie high CR) And as stated already,the inside far rt corner headbolt/stud has to be shorter due to block (presume d15b2?)
Read the above links,socket+chip a pm6 ps9 pr4 OBD0 ecu,remove the oil control jet,set your CR w HG choice/removing or adding layers to a Y8 MLS HG,or buy the correct cometic or similar,run the extra wiring for vtec solenoid/do mpfi conversion if not already,etc... Search IS ur friend!

 

That information was great. I have two questions. One: which head studs do I use since one has to be shorter? Do I buy a set for the Y8 and a set for my D15 head and mix and match? and which one needs to be shorter? Also, Most of the stuff I've read tells you to get an OBD1 ECU and run the extra wires. Is there a huge benefit to doing that as opposed to running a switch and relay? I'm on a tight budget, so I want to know what will work the best for the least amount of cash. Thanks for all the support everyone!

 

The end on psgr side closest to firewall is the headbolt that needs to be shorter,and stud kit really only needed if boozting. (use one of your d15b2 bolts there,you'll see what needs to be done after trying)
Some prefer OBD1 (for tuning ease/more software support + choices,but I stay OBD0 w my EFz and use TurboEdit to tune) No relay or rpm sw needed if ecu socketed/chipped! (the rpm sw is only used to activate vtec,and not the best of methods) And do NOT try + use a ghetto switch,lol! IMHO,for what you'll usually pay for an OBD1 vtec ecu-you can have an OBD0 chipped/basmapped to start tuning from... G'Luck!

 

So what you're saying is I could buy an OBD0 ECU just like the one that's in my car now and take it somewhere and have it chipped and just unplug mine and plug in the chipped one when i do the swap and it'll be good to go? It seems too easy.

 

Also, what obd0 ecu's will work for what i'm trying to do specifically. Like i said, I don't know anything about the electronics of a honda

 

None really work without some form of modification.
If you can get a PR3 from an OBD0 B16 then it will have vtec hardware in it, but the mapping will be all wrong for your application. It should be chipped with SOHC vtec mapping to get it in the ballpark running decently - get your car tuned for best results.
Other option is to search for 'one wire vtec' and mod a PM6. PM6 stock maps will run your engine LEAN in vtec so, again, you will need to chip it for proper mapping - tune it for best results. You will also need to add the required hardware for the vtec control

Price adds up fast for ECU modding and tuning. Hopefully you can find some good deals on the hardware and tuning won't hit your wallet with such an impact.
The price to converting to OBD1 and run a P28 starts looking good really fast if you can't find any deals.
The stock P28 maps run really decent so you don't need a tune as badly - of course nothing runs as well as a map tuned specifically for your car.
(You can run the Y8 head with OBD1)

 

So to me it sounds like running OBD1 would be a lot easier, and possibly cheaper if I don't find a great deal on tuning. This car is my DD, so I'm trying to get everything together for the swap and do it in a day.

 

I just found a deal on a Y8 head with manifolds, fuel rail, tb, everything. $125 bucks. I'm going to pick that up to start my collection. Does anyone know a good spot to find the one wire vtec harness or the OBD0 to OBD1 harness connector or whatever they are?

 

^^egay

 

Good old ebay...

 

streetlightz.com is where i got mine