Trying to do a head swap, looking to pick someone’s brain
07-27-2018, 12:38 PM
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Trying to do a head swap, looking to pick someone’s brain
Hey guys, been reading up on some stuff and just trying to get it all straight. Seems like everywhere i look there is a different answer. Got a 91 DPFI hatch, blown head, and a hatch full of parts right now, just trying to get some clear answers from some people who have done this before
First thing i want to do is get it running. Going to swap a Y8 head on it that i snagged pretty cheap from a local yard. I figure I need to get a new head gasket, fluids, plug wires, adjustable cam gear, figure out the timing belt, and head bolts. Everywhere I read says something different about what head bolts to use. Some say use 1 Y8, some say 2, either way, is there anywhere i can just buy a couple of them? Every part site i see only sells packs. Is there anything else I’m missing here? Seems fairly straight forward there, just haven’t done a head swap before.
Next step will be MPFI, couple questions here. I have the Y8 IM as well with the head, no injectors or anything. If i find some non obd injectors and a fuel rail from an MPFI ED/EF, am i good with the Y8 IM? Also, do i use my stock throttle body or will i need a matching one for the Y8? I’ve got the manifold, a PM6 ECU, MPFI dizzy, so i think i just need injectors, and a rail. But when it comes to injectors, i see a lot of mentions for the resistor box. They still sold anywhere or am i stuck finding one off of a car?
Final step/questions - wiring up VTEC. Anyone out there still chip/tune the PM6 to run a VTEC map? Really not trying to do an obd conversion if i can avoid it, so if i can just wire up VTEC to the ECU i have that would be the ideal way
First thing i want to do is get it running. Going to swap a Y8 head on it that i snagged pretty cheap from a local yard. I figure I need to get a new head gasket, fluids, plug wires, adjustable cam gear, figure out the timing belt, and head bolts. Everywhere I read says something different about what head bolts to use. Some say use 1 Y8, some say 2, either way, is there anywhere i can just buy a couple of them? Every part site i see only sells packs. Is there anything else I’m missing here? Seems fairly straight forward there, just haven’t done a head swap before.
Next step will be MPFI, couple questions here. I have the Y8 IM as well with the head, no injectors or anything. If i find some non obd injectors and a fuel rail from an MPFI ED/EF, am i good with the Y8 IM? Also, do i use my stock throttle body or will i need a matching one for the Y8? I’ve got the manifold, a PM6 ECU, MPFI dizzy, so i think i just need injectors, and a rail. But when it comes to injectors, i see a lot of mentions for the resistor box. They still sold anywhere or am i stuck finding one off of a car?
Final step/questions - wiring up VTEC. Anyone out there still chip/tune the PM6 to run a VTEC map? Really not trying to do an obd conversion if i can avoid it, so if i can just wire up VTEC to the ECU i have that would be the ideal way
07-27-2018, 06:17 PM
#2
Re: Trying to do a head swap, looking to pick someone’s brain
If you use OBD1 or OBD2 injectors with your PM6, you won't need a resistor box. If you chip the PM6 to run VTEC, you won't be able to use AC, because you will sacrifice this ECU output for VTEC. You'll need an MPFI throttle body - the DPFI one won't bolt up to the Y8 manifold. You'll also need a MPFI fuel hose along with the rail. Finding an MPFI EF is pretty tough these days, so parts from a 1992-2000 are your best bet.
Not sure about the head bolts. If you do need individual head bolts, you can buy OEM...
Not sure about the head bolts. If you do need individual head bolts, you can buy OEM...
07-28-2018, 05:09 AM
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Re: Trying to do a head swap, looking to pick someone’s brain
If you use OBD1 or OBD2 injectors with your PM6, you won't need a resistor box. If you chip the PM6 to run VTEC, you won't be able to use AC, because you will sacrifice this ECU output for VTEC. You'll need an MPFI throttle body - the DPFI one won't bolt up to the Y8 manifold. You'll also need a MPFI fuel hose along with the rail. Finding an MPFI EF is pretty tough these days, so parts from a 1992-2000 are your best bet.
Not sure about the head bolts. If you do need individual head bolts, you can buy OEM...
Not sure about the head bolts. If you do need individual head bolts, you can buy OEM...
Wouldn’t have thought about the fuel hose, thanks for that tip. Would have run into that when bolting it all together so that saves a headache
07-28-2018, 05:23 AM
#4
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Re: Trying to do a head swap, looking to pick someone’s brain
You can absolutely run OBD1 injectors - OBD0 are peak-hold, OBD1 and OBD2 are saturated. Google those terms for more info, it's interesting. The primary difference between these as it relates to the ECU is the impedance value. That's why EFs have a resistor box but EGs do not. Delete the resister box and you can use OBD1 injectors.
I would specifically use OBD1 D series injectors because their flow rate is nearly identical to the originals. I've found conflicting info on D16Y7 and D16Y8 having different flow rates (lower and higher, respectively), which would lead to running too lean or rich.
In case you didn't know, Y8 manifolds are not all created equal. IAC was mounted in the IM for manual, and on the TB for auto. Keep that in mind when sourcing a TB.
EDIT: About the head bolts. Please don't re-use them. Please. I know it sucks, but it's not worth it if one stretches and you have to rip the whole head off again. Just get ARP studs so you can pull the head a dozen times if you have to.
I would specifically use OBD1 D series injectors because their flow rate is nearly identical to the originals. I've found conflicting info on D16Y7 and D16Y8 having different flow rates (lower and higher, respectively), which would lead to running too lean or rich.
In case you didn't know, Y8 manifolds are not all created equal. IAC was mounted in the IM for manual, and on the TB for auto. Keep that in mind when sourcing a TB.
EDIT: About the head bolts. Please don't re-use them. Please. I know it sucks, but it's not worth it if one stretches and you have to rip the whole head off again. Just get ARP studs so you can pull the head a dozen times if you have to.
07-28-2018, 07:55 AM
#5
Re: Trying to do a head swap, looking to pick someone’s brain
Yeah, get some OBD1 or OBD2 Civic injectors and you won't need the resistor box. The distributor doesn't care what injectors you use. I agree with scelestus - bite the bullet and get some ARP head studs. You should also have the head AND block resurfaced before you bolt it all together with a new MLS head gasket. I just rebuilt an Accord at the beginning this year and wasted about $300 by trying to just have the head resurfaced and used Mahle head bolts. I had to pull it all back apart within a month. The second time around I had the block resurfaced along with the head and reassembled with ARP studs - runs like a champ now.
As for all the other things involved with the DPFI to MPFI swap, there are lots of little things you don't think about until you're in it. Maybe I'll get around to doing an updated writeup...
As for all the other things involved with the DPFI to MPFI swap, there are lots of little things you don't think about until you're in it. Maybe I'll get around to doing an updated writeup...
07-31-2018, 06:36 AM
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Re: Trying to do a head swap, looking to pick someone’s brain
I wasnt planning on reusing the head bolts. And I looked into ARP studs, my question is, can i use just the 1.5 kit or will i run into issues with the Y8 head. Looks like they have kits for the 1.6A/Z series and the 1.6Ys so I’m assuming that there is some difference there. Would hate to drop that kind of money to only end up getting the wrong kit
08-01-2018, 04:53 AM
#7
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Re: Trying to do a head swap, looking to pick someone’s brain
Almost certain (I know I've found this online before, so it's out there) that a few are taller on the Y8- most of the time you buy the stud kit for the head you're using, since that's where the variation typically is found. There are similar issues on the B series side.
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