Help withD15Z1 performance

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cleanLS

New Member
I am kinda new to hondas so dont flame me please. Anyways I have a little china sand rail that i put a d15z1 motor in and as i said i am new to the hondas and i think i fucked up when i did this swap. I used a p-28 computer, and made my own wire harness with info off this site. The engine runs fine it has a little stumble in the idle if i let it idle for more then like 3 mins. It still runs good other then that. In my quest to get more power i let some friends talk me into getting a 91SI mpfi intank, for the bigger throttle body. I already converted the o2 to a 4-wire with the p-28 computer. I need more power. The rail is still really slow, and i am disaponted with the power. Maybe i am dumb and have the wrong computer/engine combo, but its what i was told to do.
If anyone could help i would greatly appreciate it. Let me know if i am stupid and need to get a diferent computer or what ever. I was looking into geting a nasty aftermarket camshaft, but cant find anything for the D15Z1 motor. any advise would be great. Thank you in advance chris.
 
That is the vtec-e economy engine. It is meant for low power fuel efficiency. You need to get the P07 computer if you want it to run correctly. Also, you need the 5 wire O2, so the car can go into a lean burn cycle and proper valve operation. For what you are looking for that is not the best motor for trying to do anything except get around 50mpg.
 
Basically what he said ^^^^^^^... i think youll prob want to get another swap. What kinda engine and power are you lookin for, and how much $$$$$$?
 
I dont really know how much. I mean if i could get rid of this engine i wouldnt mind spending up to Mabee $500 + what i could get for this engine. I would like to get right arounf 120-150 HP. My rail dont weigh much more than 1300 lbs. so alot of HP is not nesasary.Like i said if i could just get a little more power out of this engine that would be fine i think. I mean the rail move pretty good now just not quite enough.
I did some more looking and found a adjustible cam gear for like $130. How much power would this give? If any at all?
 
I have seen a few D-series turbo kits on craigslist for $500-$750 with everything. That would give you some extra power. That motor bone stock is rated at 92hp, so getting to the 120hp-150hp range is going to take some work.
 
A LOT OF WORK... i had the same engine, and no matter what you do all you will have is a slow ass loud annoying car. i went throught the same thing. this is what i would do if i was you. save the engine just in case anything ever happens, you got an extra gas saving engine to use anytime you dont have another engine. Try and get a d16z6 w/tranny if possible, all other trannies are too long for shifts, and build that up, or get a d15b and put a d16z6 head on it and build that. Then you will feel the power you are lookin for. like i said, the current engine you have now is just for gas saving.
 
VTEC head or A6 head; PMS or P08 pistons; with dyno tune/chipped ECU(the P28); done.
 
VTEC head or A6 head; PMS or P08 pistons.... on the same block? what will this do? and how much would it cost if you took it to a shop? just wonderin
 
yea what he said^^^^^^^ Those pistons on this d15z1 block? I'm no expert, but that wouldnt do anything unless the pistons are domed for high compression. Oh and what is a A6 head? You also said mabee a vtec head, i already have a vtec head, a shity one i am being told, but a "vtec" head none the less.
 
So i have another ? Can i just swap the D15Z1 head off, and put like a Ex of Si head on the D15Z1 block? Or do the water holes not line up? Or will there be a valve to piston clearance problem?
 
the 88-91 EX/Si's have a D16A6; it's non-VTEC but still a great head. The VTEC heads I was referring to are the D16Z6 and the D16Y8 heads(EG and EK Si's/EX).

Those pistons have more dome/less dish than what the Z1 comes with; and the compression height will work correctly with your engine. The Z1 has a -15cc dish IIRC, the PMS(from the GX D17), has a 4cc dome but sit's .75mm lower in the block, and P08(from JDM D15B VTEC) has a -4cc dish with same compression height.

Yes, another D-series head will fit on there. If you go with the non-VTEC Si head, you may have to install an oil plug in the VTEC oil port(although some people have got away without installing one; but others have had oil leaks because of it).
 
the whole engine you have is made to save gas, not burn it. EVERYTHING! maybe you can do what the other guy said and switch that stuff out, but like i said, how much is it gonna cost?
 
I dont know man. How much would a head at a local Junkyard go for? There is this local JY that has like 3 90-91 si hatchbacks. But i dont know if the head off one of those is worth it. If i get one of these heads then it wont be vtec. Witch i am ok with, but then what do i do with the wiring harness i made. Could i still run it just put all the obd-1 sensors in the 91 si head, and change the computer to a obd-1 non vtec? I really dont care about vtec.I also guess i would be content with like 90-100HP.
 
I was also thinking, what if i was to push the vtec pin though the rockers (like if the vtec solinoid was active) and then weld the pin in place?Then disconect the vtec solinid. Then (in thery) the motor would run like a non-vtec 16 valve, but with a milder cam profile. I weld for a living, so i wouldnt be worried about my weld holding. Especialy since the pin is actually holding the rockers together.
 
i dont know about that, but i know your engine is gonna need a lot of $$$$$$ to make it fast, just buy d16z6 or d15b block and d16z6 head, swap it out sell your swap or save it, roll one up ... and call it a day. or keep the engine you have now, be slow, loud, and annoying as hell but save $$$$$ on gas for grass. your choice, im tellin you this because we just swapped my homies d15z1 out. It was slow, annoyin, and loud. Everyone always wanted to race him and if he did i would get murdered, now no one wants to race him .... he had $$$ and did a type r swap
 
oh yea, and my homies d15z1 had all the bolt on upgrades you could think of. Thats why it was so dam loud,slow and annoying!
 
Ok so will a d16y8 head fit on this d15z1 block? I have a line on a d16y8 motor for $75, but it has a rod knock. So if i get this motor, will the head fit on the d15z1 block with out piston/valve clearance? I mean shit i already have my wireing harness and if i just take all the sensors out of my z1 obd-1 head and put them in the Y8 it should work right? Let me know quickly please if it will work i need to buy the motor tomorrow. I am busy the rest of the week. And the guy is going to take it in to get his $75 core back next weekend if not.
 
no, its not gonna fit, and you cant put a head on that engine. i dont think it will make a difference. if you want to keep the engine you have now its only good for gas saving so just saveup with that money you save on gas, maybe one day you can even buy an itr;). Good luck with whatever you do
 
Well i did some research on d-series.org and found i CAN put the y8 head on my motor. It is actually is a very good combo for turboing. It will void around 8:1 compresstion. But very bad for Na. I could have the head milled about 40 thousands, but it would cause a little grief with the timming belt. so i opted to kept what i have for know and will get another motor later. I am however going to wire the vtec to a rpm switch and disconect the wires from the ecu. It will triger the CEL but i dont care.
 
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