Mini-Me VTEC Head Swap
Thanks to Mike H. for letting me use his picture!
YELLOW text is additions/changes that I have made. Updated 10-28-00
VTEC head swap info.
I have not done this swap but know a guy who has. Any questions and I can check with him. It seems relatively simple though.
I got this from various sources on the internet. AGAIN, USE AT YOUR OWN RISK!!!
If a6 block, z6 head, use the following
5g Si/EX Honda (oem) metal head gasket
5g Si/EX Honda or NAPA timing belt
4g Si intake manifold/TB/sensors/ECU
4g Si injectors/resistor if yours isn't PGMFI to start
5g Si/EX Honda VTEC solenoid rubber seal (replace it, trust me)
4g Si upper radiator inlet neck (connected to head)
Compression on a6/z6 combo = 10.4:1 (per Ben Mullins)
MSD rpm switch / rpm selector module / 4 wire 30A relay
This list is relayed via memory from my swap on a 4g Si. Nice combo, runs strong, don't expect VTEC to knock your socks off, it won't. But easier/cheaper than full
ZC/B series swap.......
More on vtec swap again from internet sources
Hopefully this will clarify some issues...
1. You DON'T need a 92-95 oil pump. It's a good thing to throw in if you are rebuilding your block, but it's not required.
2. You CAN'T use 92+ injectors with 88-91 ECU because the former are peak/hold and the latter saturated. Don't worry about it, the flow rates on all 88-95 injectors as well as 90-93 Integra injectors are the same.
3. There's no additional wiring needed when putting a SOHC VTEC head on an Si block with Si manifolds except for the VTEC controller. (Make your own, see Hybrid board.)
4. Field's VTEC controller can be spliced in between your ECU and the wiring harness. (Only 5 wires or so.)
5. 88-91 Si intake manifolds fit perfectly, no need to switch really. (Although 6G manifolds are much bigger, so if you have the money... You'll also need the same year
EACV, TB, and fuel rail.)
NOTE:The manifold will fit but the ports on the
head are slightly bigger than the intake manifold. Might be a good thing
to stop intake reversion.
6. You CAN'T use the 92-95 ECU unless you do a harness swap or solder all 45 or so wires from the 4G harness to the 5G ECU. Plus you'll have to deal with OBD crap and such stuff. Short answer: don't bother.
7. 88-91 headers will fit. The bolt pattern is the same but the ports are not really. If you have money, get your existing headers ported, else just keep them as they are. It's not really that bad.
NOTE: The header needs to be ported at the bottom.
8. You DON'T really need to take the oil control jet out of the 88-91 Si block, but it's recommended. (Works fine with the jet in the block.)
NOTE: This is incorrect. The VTEC heads have
the jet made into the head, so remove the jet from the block.
More vtec head swap info again from the internet -------------------------------------------------------------------------------
Ok, this will hopefully clarify some things.
1. 92-00 SOHC VTEC heads DO FIT on 88-00 SOHC blocks.
2. SOHC VTEC oil pump is not required, but definitely recommended if you are rebuilding your block.
3. Taking the oil control jet out of the 4G block is recommended, but seems like things work fine without this mod.
4. The 96+ head is NOT Z7, it's a D16Y8. It features a square combustion chamber, higher CR, obviously, and you don't need to drill holes with it when using a 4G distributor with it, like you need to with 5G heads. (Read below for CR info.)
5. If you are rebuilding your block, B18 rods fit if they are professionally machined. (Too big for D-series otherwise.) D16A1 (1st gen Integra) rods fit fine and require no
mods. They will hold up to 220 hp.
6. AFAIK no one has tried the D16A1 pistons with a mini-me setup. They do give you higher compression, but there's probably not enough valve clearance. The CR would be higher than 12:1, too high for street use.
7. D15B2 block (4G DX) with D16Z6 head -- CR of 10.6:1.
Also here's some more info from the Hybrid board:
First of all, mini-me, as well, as LS/VTEC is SMOG ILLEGAL. (Don't know about auto-x implications.) Question is though, how Honda-savvy does a smog tech/ref need to be to tell a hybrid like that? Well, if that doesn't stop you (didn't stop me), read on.
General parts list:
any 88-00 SOHC block
any 92-00 SOHC VTEC head
headgasket matching the head
timing belt matching the head (use VX for 1.5L)
VTEC controller (make your own, Field, whatever)
Other mods: take out the oil control jet if using a 4G block. (Jim, yours works good with the jet in place, right?) If using a 4G
distributor with a 5G head, the holes don't line up, so modification is required. (The usual 5G swap headache.) Apparently, no such
problems with 6G heads.
(Note the SOHC VTEC heads have the oil control jets in them already so take the jet out!)
Intake, injectors, distributor, ECU: at the minimum you can keep what you have. For 4G, it's best to use everything off an
Si.
Get a 6G intake manifold/fuel rail/TB/EACV if you have some spare $$. (Bigger manifold, longer intake runners.) Still keep original distributor, ECU, injectors. (Easiest.)
4G headers bolt up but ports are not the same. Porting would be good, but not absolutely required.
Any 88-00 D-series intake bolts up no prob. You should be able to keep your FPR with whatever fuel rail you end up using.
Distributor: use the one corresponding to your ECU. .Sparkplug wires: I would say use those corresponding to the head, but
I hear the original wires work as well.
If you are rebuilding your 4G block, invest in a SOHC VTEC oil pump.
CR per Ben Mullins:
d16a6 block, d16z6 head: 10.4:1
d16a6 block, d16y8 head: 11.2:1
You can keep the block internals stock or do some mix-and-matching if you want to rebuild it for N/A or
turbo.
Email Me with any questions on this swap. I am seriously considering this swap once again. With a good cam and solid bottom end it should stand up quite well and be real reliable. This is what I am looking for.