Spade

I have been asked this a few times now and I figure that it is time to make a post about it.

The D16Y5 engine is a VTEC engine. However, it is a VTEC-E engine.
E = Efficiency

The cam in the Y5 is a 4 lobe cam not a 5 lobe cam like the Z6 or Y8.
There are only 2 lobes on the intake side of this particular engine, which are called the primary and the secondary. The primary has a much higher and longer lift/duration ratio than the secondary. At low RPMs (below 3,000) and light accelerator pedal pressure the rocker arms follow each lobe. However with more aggressive pedal pressure VTEC-E will engage at 2700 RPM. This is because the secondary lobe opens so little that the engine basically suffocates at higher RPMs. Once VTEC is engaged however, the engine has no trouble breathing because both rocker arms are locked together and follow the primary lobe, much like the standard VTEC (locking the rocker arms together to follow a higher cam lobe).

So, with that little bit of information shared, the following should be obvious.

If you plan on putting a stock GSR/SI/EX/Type R ECU on that engine you had better have a VAFC or some sort of RPM activated switch that will enable you to engage VTEC at 3,000 RPM’s or face a serious bog in power until those particular ECU’s are programmed to engage VTEC.

The Professional

Great info!

Thanks for sharing with us your findings. I H-T.

HXMan

Yea, if you have an HX, DON'T put anyother ecu on it. The hx ecu is pretty advanced in itself...and with the engines special properties it is pointless to swap it out.

Spade

Top for day morning guys.

JDMvtecDRAGSTA

these articles should be put in some tech archives or something

spade: quick question regarding the hx, are the wire harness the same for 96-00 civics(including hx?)

Spade

Nope. The 99-00's had different wiring than the 96-98's

The EX and HX both have VTEC wiring however, the HX also has EGR wiring.

Shawn C

iTrader: (1)

Well i've got one for you then- when i was building my gsr, i wasn't sure if my ecu was good or not, so this girl lent me her 97 HX as a ginuea pig (sp?). I plugged in the gsr ecu and took it for a test drive. that thing pulled like none other. where the car would normally redline, it took the hell off, and pulled hard til 8300 rpms.

I was VERY impressed. I wouldn't recommend revving this particular engine that high all the time, but it does have the roller follower system, so i wasn't that worried. The car had the CEL on while i was driving it, but i knew it could be several things. Any thoughts or comments on this?
Shawn
BTW- this car was bone stock

pbomers

If i'm not mistaken the HX also has a wideband 02 sensor stock. well...sort of. it's the same one you would use for a DIY wideband. hopefully the ecu actually tunes from it!!!

Spade

Yeah but what was the power like between 3K and 5k?
That is where u loose out. I agree though with more fuel that sucker halls ***. However, I am unsure of where the power starts to drop off due to the cam.

Spade

Not verified.....the VX had it but, the HX is unknown.

HXMan

Hx has a wideband O2 sensor.

Also while most civics wire harness did change from 96-98, and 99-00...the Hx stayed the SAME from 96-00. At least that is what it says in my Helms manual.

Uncle Ben's

Back from the dead, with a related question. I have a 98 EX with an engine that has seen it's best days. I am looking into an HX swap for the increased fuel mileage, since if I'm eventually going to have to replace the long block, I might as well do this since finding a good deal on a clean 5 speed HX is very elusive. If I can find the whole HX swap for cheap, for the mean time will I be able to put the HX ecu in my car and see a reliable increase in economy with the Y8, even with the code for the different O2 sensor(before I get around to doing the swap)? Also, when I do this swap, will the new O2 wiring plug right into the new engine wiring harness, meaning I will just be able to then plug in the HX ecu and be done with it? Will there be any physical wiring I will need to do?

Jason C SBB

The HX uses a wideband O2 sensor which has 5 wires. The regular O2 sensor has 4.

I reckon if you swap to a Y5 motor you may need to run some new wires to run to the Y5 ECU.

06HX

Other than a direct replacement,I cant see why you would want to? What,if any,advantages would there be? HX are a different beast in a lot of ways.Most of them good!

That said though, with the dirth of any performance-enhancing items for this model out there (almost everything Ive looked at lists parts for LX,DX, etc.) Does anyone know of any simple (non-turbo) tweaks that are worthwhile for the HX-without sacrificing my avg. 35 mpg too much?
The main thing I seek in mine is a bit more torque-short of constantly revving the hell out of it. Where I live is flat as a pool table,but we have some tall bridges in town-if Im not doing 90 by the time I reach the inclines, Im struggling to get over them.

Jason C SBB

A lot of hi perf parts for the Y8 will work for the Y5.
Short of FI or more displacement, there's precious little you can do to significantly add midrange torque to the motor.

99civichx

question here too!!! im turboin my 99 hx (first turbo car, cant wait!!! ) and the only thing im scared of is the ecu, do i gotta replace the ecu or use a plug and play or what??? its not gonna be a big **** load of boost prolly 8psi to 10psi at the MOST!!!! what should i do??? im like pullin my hair out here!!

99civichx

anythin guys???

99civichx

will someone plz help me out???

94EG8

You'll have to get an OBD1 ECU and chip and tune.

99civichx

ok.. what would u think??? cause im on a big *** budget right now

turbohatch96y7

iTrader: (15)

I got a question if you boost a bone stock hx can you use the same ecu?
Or do you just go obd1 and tune from there would you still be able to use the two diffrent engagement points?

SeaMus MaCk

Hey hopefully someone can help me out...I have a "D16Y5" Block...with a
P2J-3 "98" on my head...can someone explain to me what head is on the block...if they belong together?...It's a 94 DX shell with the motor listed above in it....also what ecu is supposed to be in the car?

Putzman02

The D16Y5 shares the same head casting as a Y8 so its a good possibility that you have the correct head on your block. It is supposed to be ran with an OBD2 P2N ecu.

Putzman02

And as far as boosting a stock HX, you might be able to get away with using the stock ecu if you don't boost over like 6 psi. But you can't tune the stock HX ecu so it's not recommended. Best bet would be a P28 with a PO7 basemap and tune from there. There's only 1 VTEC engagement point on the HX btw. You might be thinking of the 3 stage D15B.

HondaDseries

Yeah I just swapped my D16a8 to a D16y5 and I'm pretty sure the new engine I put in didn't come with an ecu and it has VTEC E witch the other engine I had was a normal VTEC but anwyas my question is why would my VTEC not kick I can't feel or hear it at all would it be because I didn't put in the ecu that goes for the D16Y5 engine cause I had a auto repair shop do the swap and they didn't tell me anything about the ecu. Please help my VTEC is connected and hooked up but when I unplugged it no difference in power it was the exact same so the VTEC isn't working at all...