civicjoe

Hey guys I've read through probably 50 or so threads and probably 5 or 6 how to's. None of them are really that great at discussing these issues that come to mind. By running a Y8 head on a non-vtec D16 block you are changing some of the core characteristics of the motor. I am going to refer to the zealautoworks compression calculator. http://www.zealautowerks.com/dseries.html

My plan is to do the common mini-me swap I've got a stock D16Y7 and I'm going to put a D16Y8 head on it. I plan to convert to OBD1 and use a P28 ECU. At first it seemed too simple, swap the heads out and gain 20 or so horsepower. I began to think about it, a question came up, then another, I searched ALL the how-to's and have searched every mini-me swap related thread on the internet (almost.) I still have some questions that I cannot find answers to. Hopefully the pros on here can sort out a lot of questions that I have.

From what the calculator tells me I am going to have a compression ratio, depending on what headgasket I use and how much my head has been milled. I bought the head already milled so I don't know how much has been taken off.

Scenario #1 - nothing has been taken off the head, use the thickest headgasket available. Puts my compression ratio @ 9.72:1

Scenario #2 - assume my head has been milled 40 thousandths and I use the thinnest headgasket. This puts my compression ratio @ 11.32:1

Compression ratio has a big influence on how a motor reacts and performs. If I can't hardly know what compression ratio is going to be how is the ECU going to figure that out. I'm using a computer off of quite a different motor, I understand that as more air enters the motor the ECU will add more fuel. Except @ WOT where the ECU goes into open-loop and follows set maps. With many different configurations of compression how do I know that the P28's open loop is going to be good for my setup?

What's a safe compression ratio, is 11.32 going to affect engine reliability and longetivity? I'd love to have the hp increase from such increased compression. What octane should I be able to run with 11.32:1 compression?

I have a few more questions, I have read in some how-tos that ALL D-Series manifolds are interchangable, I have been told that they aren't. I'd assume that they may have a bit different designs but I'd think that they'd bolt on and work. If someone could explain this I'd greatly appreciate it.

Speaking of the manifold, I've also heard that my IACV will NOT work with my mini-me swap. Is this a matter of just the pigtails not matching up? Can I just wire it right in instead? IACV are usually located on the TB, will I need a TB off of a D16y8?

As long as were talking air we might as well talk fuel because it's important too. Can I use my injectors off of my D16Y7 motor or will I be required to purchase some off of a D16Y8 motor?

My main point is , if I have all these variables and questions, how in the world is my ECU going to know how to run the motor?

I'd like to start some good discussion on some of these issues and hopefully get my questions answered. If I seem a little ignorant on some of this please forgive me, I'd just like to get the CORRECT information because a lot of it contradicts.

Thanks Guys, I hope that this wasn't too long of a read.

EDIT* Thought about it some more, maybe I'm just freaking out but I KNOW the ECU isn't going to be able to calculate all these variables and it seems I am going to need some type of tuning device. I don't want an S-AFC because I hate piggyback controllers. I don't want to run hondata or crome because that would cost too much right now. I could type on this forever but I need some input from some other members...

phatrick2332

Now you have got quite a bit there and im going to try and lay it out the best that I can.

You don't have to run the thinnest HG you can on this engine, then you could have a compression ratio that is in a more useable range for your needs. A higher compression ratio isnt going to be really beneficial without a cam, cam gear and the other usual bolt ons. Basically you cant just throw compression at an engine and expect it to perfom, its a combination of the parts that you choose that make a setup prove its worth.

About the ecu, if your going to be running in the ~11:1 range, you are going to need to tune the fuel/timing maps. You would be asking for trouble trying to get the stock ecu to handle the additional needs that the increased compression will demand.

Your best manifold choice would be a y8 mani, larger plenum volume and it is basically considered to be the "type R" of the dseries manifolds. The reason that you run into a problem with the prior IAC's is because yours is a 3 wire and the previous IAC's are a 2 wire design. I dont believe that you listed what your running the combo in, but obviously its obd1 considering you mentioned running a P28, so you could also just use the intake from a z6 and have no problems at all.

The IAC is located on the back side of the intake manifold on the plenum, the MAP and tps are located on the throttle body. You do not "need" a y8 throttle body, you could run a z6 or a bseries TB on either the z6 or y8 manifolds. There are many threads about using the y8 intake on 92-95 cars and which throttle bodies you are able to use on each.

If your running and ecu that requires the use of a resistor box then you need to run injectors that also require the use of that resistor box. I believe that the y8 injectors do require a box, and the z6 injectors do not. If your using the P28 ecu, you need to run the injectors from the z6. Im not 100% sure on this portion, only about 85%, im sure someone will chime in.

You dont need to purchase hondata, there are a ton of other options these days for tuning for a much lower cost. You just need to remember, There is no sense in building if your not going to tune it properly. Your engine will not last very long and you will not be pleased with its performance without it.

I hope I touched on most of your points, and if I got something wrong, im sure I will be corrected by someone else shortly.

Good luck with the build

Pat

civicjoe

thanks for the reply,

I think I'm going to try and use the lowest compression that I can. I understand all the workings of a motor and what makes a good setup but I don't know the line where it's a good idea to switch over to a chipped tunable ecu. Right now I'm thinking hondata is my best option for a few reasons. With piggyback or hack controllers like the S-AFC you can't tune ignition timing and fueling separatly, which is something you want to do. I don't like crome simply because some tuners won't tune with it, I've played around with it a bit and sometimes when u change things like injector size, it will change the maps but it will still say it has the original injectors. I've also heard a few stories about it not working well with turbo motors. Granted a bad tune will ruin any motor no matter what it's running.

Alright now that my rant is over... I'm thinking I will just get the stuff together I need for the vtec swap and then call it good. I'm still piecing together a turbo kit...
Oh and I've got a 2000 Civic CX which came with the D16Y7 and is OBDII of course.

civicjoe

forgot to mention I dissassembled my vtec head and did some PnP, I got rid of some casting flash on the intake side and I did a lot of polishing on the exhaust side, I also tried my hand at knife edging the exhaust ports.

I did it more for the experience than the gains, I know it won't do much. I was going to go further but I don't have a spare head to practice on. I'm no pro and the thought of messing something up...


EDIT: I'll post some pics up later