Realize the full Performance/Economy Potential of a Honda Civic VX

[suspendedhatch]

Fixed my spoiler. It had melted in the sun. Well the guy at work gave me one he had. Just so happens to be the exact same color as my car.

Before



After




Hey, can't hurt aerodynamics to get that fixed, right?

[hondaguy72]

Life is drama. I'm finally used to it.

I'm excited to see the results of your long weekend's pursuit. The final tune on the car would be a valuable commodity. It could be sold as a swap tune with an EMS for decent coin. Package it with the complete needed parts and you could have yourself a little cottage industry.

[Big[V]]

suspendedhatch, keep up the good work. I'm running a D15Z7 on my CVT EK3.

Haven't read through all your posts yet so pardon me if you already covered the following:

1. Have you considered bumping up the CR whilst using non premium gas such as RON91? i.e. using PMS (est 11.3 CR) from 01-03 GX or PLD pistons from D15Y4 (est 10.2 CR). Honda Japan's website 10-15 mode for Y4 is 20km/l on CVT but so far no piston info though (compression height, dome/dish cc etc)

2. Bumping up rev limit till 7500-8000? Z7s have the same R/S ratio as the B17A and K20A at 1.62. I believe Z7 can still make power there and can be done with your EMS.

3. Advance the timing during low rev range and retard on highs with your EMS? With that you'll have the equivalent of the L15A i-Vtec

ps: You're probably the first using AEM EMS on EG hatch, but there is another guy using it on his EK3 Vi-RS in Sri Lanka

[suspendedhatch]

Originally Posted by Big[V]

suspendedhatch, keep up the good work. I'm running a D15Z7 on my CVT EK3.

Haven't read through all your posts yet so pardon me if you already covered the following:

1. Have you considered bumping up the CR whilst using non premium gas such as RON91? i.e. using PMS (est 11.3 CR) from 01-03 GX or PLD pistons from D15Y4 (est 10.2 CR). Honda Japan's website 10-15 mode for Y4 is 20km/l on CVT but so far no piston info though (compression height, dome/dish cc etc)

Replacing the pistons is the equivalent of rebuilding the engine. That's something that I have to pay someone else to do. If money were no obstacle then I would have the Endyn Roller Wave pistons installed.

http://www.theoldone.com/components/pistons/index.html

2. Bumping up rev limit till 7500-8000? Z7s have the same R/S ratio as the B17A and K20A at 1.62. I believe Z7 can still make power there and can be done with your EMS.

3. Advance the timing during low rev range and retard on highs with your EMS? With that you'll have the equivalent of the L15A i-Vtec

You mean cam timing? No, the cam timing isn't infinitely adjustable like it is on the iVTEC motors. It's the physical design of the VTEC switching mechanism that prevents that kind of control. VTEC solenoids and valve train setups before 2000 were either On or Off. They weren't pulse-width-modulated.

ps: You're probably the first using AEM EMS on EG hatch, but there is another guy using it on his EK3 Vi-RS in Sri Lanka

No no no. There are lots of people using the EMS on EGs. There's only one person using the EMS on an EG with a D15Z7. But I'm not so self-absorbed that I take pride in that. I wish that there were others out there so we could share information. I would gladly share my calibrations and experiences to anyone as crazy enough to take this route.

Thanks for your interest and your information! Info about the stock configuration of your motor would be extremely valuable. Do you have an english language repair manual for the D15Z7? Would you be able to sell it to me? Do you know the stock load/rpm/tps requirements for engaging the first stage VTEC (12 to 16 valve switch)?

[Big[V]]

Lol I did meant you're probably the only one using AEM EMS on a Z7 AND in a EG hatch.

I didn't mean changing the cam timing. I meant the ignition timing through EMS. i.e. advance a few degrees on low rpms and retard on high rpms.

Till date I have not sighted the english version of the shop manual with D15Z7 in specific. But the spanish version is available. Just wish I could translate the whole pdf into english.

http://downloads.hondatech.info/Auto...da%20Civic.zip

You can also try this manual

http://downloads.hondatech.info/Auto...e%20Manual.zip

Although it does not have the Z7 in specific, its 12-16 valve switching is the same in the Y5. I have not research in further what the controlling parameters that determines the engage/disengage for the vtec-e though.

How much would the roller wave pistons cost? can the stock honda piston rings be used? looks like it calls for 0.5mm overbore to fit them.

Its very hard to find further research on Z7s. All other forums are looking power up top but I prefer having both superior fuel economy and reasonable amount of top end power.

Keep it going.

[suspendedhatch]

Actually if you could get me a manual in Spanish, that would be great. My fiance is bilingual. Do you have Paypal?

Having the EMS and a coil on plug conversion means that I can run any ignition timing I want. The D15Z7, being an OBD2 D-series, doesn't require much timing advance. It's quite an efficient head.


Ignition Timing
In general ignition timing should advance with RPM and decrease with load. It should also advance when the fuel mixture is leaner and retard when the fuel mixture is rich. Lean mixtures take longer to burn and require more timing advance than rich mixtures under load. Under heavy load, you tune the ignition timing for Minimum Best Torque (*the least amount of timing advance you can run and still get max power), then you back off slightly for engine safety. Sometimes the engine begins to knock before you reach max torque and in that case you can't run an optimal timing w/out changing to a higher octane fuel. Under light load, again you tune for minimum best torque (in fact you ALWAYS tune ignition this way except at idle) but this time you don't have to worry about engine damage. You're just as likely to wear out the engine with overly retarded timing as you are with overly advanced timing. Retarded timing causes overly hot combustion while overly advanced will cause pinging and will also fight the pistons on their way up to compressing the mixture. You can get the same mpg gain by optimizing your light load ignition timing as you can by leaning out your light load fuel.

The AEM EMS wouldn't be a standalone if it didn't give you full control of ignition timing just as it does with fuel. Here are some screen shots of the EMS software with the ignition controls loaded up. Note that you can click on and manipulate the graphs. You can change the perspective to check for smoothness.


AEMTuner (still in beta)



AEMPro

These screen shots are of the included Honda basemaps. I'm not ready to present my ignition map yet.

*If you watch the torque output on the fly on an eddie current dyno as you increase the timing (and keep load and RPM locked), power will increase, then plateau, then start to fall. Usually just as it begins to fall you get abnormal combustion.

[Big[V]]

The Spanish manual is here as mentioned earlier

http://downloads.hondatech.info/Auto...da%20Civic.zip

It has all the info you need on the Z7 in Spanish.

Whilst the other link is in English, but doesn't have Z7 in it. the closest cousin is Y5 in it.

That's what I meant as I noticed you are using coil on plug and EMS. With that you have full control on ignition timing at your finger tips. But thanks for the elaborate explanation though.

[suspendedhatch]

Originally Posted by Big[V]

the closest cousin is Y5 in it.

True, but be careful with that assumption. I've found that the ideal VTEC crossover point is different on the Z7 than it's closest cousin, the Y8. So who's to say the Z7 VTEC-E crossover point is the same as the Y5? We already know that the Z7 lacks the roller rockers found on the Y5 and Z1. It remains to be seen how the cam measurements compare to the Y5, Y7, and Y8.

Coil on plug allows for more precise control of ignition timing (less delay between the trigger event and the plug actually firing) but truth be told, the timing itself doesn't vary when you switch from distributor to direct-fire. The major benefit to this conversion is increased reliability (especially on a Honda). The conversion requires a CDI module which provides twice as much power and multistrike which fires the spark across more degrees of crank rotation.

But thanks for the elaborate explanation though.

I like to use people's questions/suggestions as a jumping point to expand the thread and document the tuning process as well as my own learning process.

[suspendedhatch]

"3-etapas VTEC"

That manual isn't Spanish. It's most likely Filipino which shares a lot in common with Spanish. They use the English abbreviations ie IAT, VTEC, ECT etc. Here are a few factory settings I've gleaned.

D15Z7 OEM Specs
DFCO above 1200 RPM*
Rev Limit 7300 RPM
Base Ignition Timing 12 +/- 2 (same as all 96-00 D-series)
Idle Speed MT 650 +/- 50 RPM
Idle CO% .1 max
Compression Ratio 9.6:1
Recommended Octane 91 RON = 87 CLC (USA)
Fuel pressure (vacuum hose disconnected) 33-40

*Interesting. I've been using 900 RPM and it works fine

It uses two O2 sensors like all OBD2 engines, both of them narrow band.

It has a special knock sensor.

5 Speed Gear Ratios*

5 Speed Gear Ratios (same as D16Y5, D16Y8)
3.250
1.782
1.172
.909
.702
final 4.250

*I'm using a 92-95 Civic SOHC VTEC LSD tranny
3.250
1.909
1.250
.909
.702
final 4.250


D15Z7 Cam Lobe Height
Intake
Primary 36.662 (1.4434) *close to Y8
Mid 38.274 (1.5068) *same as Y8
Secondary 32.291 (1.2713) *same as Y5
Exhaust 38.008 (1.4964) *same as Y8

Here's some others for comparison

D16Y5
Intake
Primary 38.427 (1.5129)
Secondary 32.292 (1.2713)
Exhaust 38.784 (1.5269)

D16Y8
Intake
Primary 36.778 (1.4479)
Mid 38.274 (1.5068)
Secondary 37.065 (1.4592)
Exhaust 38.008 (1.4964)

Valve Relief
Intake 58 (2.28)
Exhaust 58.7 (2.31)
The D15Z7 is the same as the D16Y8.


There's nothing specific about what load/RPM the VTEC crossovers are.

[Nden]

fantastic mgp with ur mods & realistic daily driving. i like to drive with windows down or partially open too in the warmer months. its ur thread and lots of great pics/411 for what ur goals are.