HMTforlife

Z6 built with vitaras/rods, Y5 head. I know it can be optimized a bit but just looking for input on the timing values under boost.

98vtec

its kinda hard to tell how safe it would be to advance the timing more due to the automatic honda ignition advance in the background, but from my experience you should be able to run a good bit more timing in the boost columns. Can't really give you much help, but i would say to read the spark plugs to give you an idea of where you stand.

how much boost are you running? what compression? gas octane?

we need more info on your engine.

0mtber

iTrader: (2)

I would recommend you get the car on a dyno. Crome's ignition timing is not as "controlled" as it should be. A lot of stuff is happening behind the scenes that needs to be handled.

Hondata, Neptune & eCtune don't have these issues.

HMTforlife

Right now it has a .48/.60 T3 which I will probably max out the 2.5 bar MAP sensor with. I just wanna see how it performs before I put in my t3/t4. I'll be running roughly 22 psi.

The compression is super low, ~7.7:1 CR. 93 octane gas

Don't have enough cash for a dyno at the moment, just wanna see your opinions, thanks so far. I was thinking it was a bit conservative, what is the most timing you'd run @ 22 psi ~7500 RPM?

98vtec

i've never tuned a really high hp turbo motor, but just from asking a few other tuners who have, i would probably start at 11* and read the spark plugs doing street tuning. I have a thread for how to do this properly in the faq if you need an explanation on how to do it. With this compression i would guess that you would be able to run NA style ignition timing at lower boost boost levels. But i dont have any proof of it or experience.

blundar

be *very* cautious with a Y5 head, unless that was a typo.

The Y5 flows totally differently and has much lower timing requirements than even a Y8 head. Your compression ratio will ofset this quite a lot. Net result: very difficult to guess timing.

Learn to read plugs because that's the only hope you have w/o money for dyno time.

ralph11sec

again, u have to bring it to a dyno to check for proper ignition tuning. like what mtber said, crome is known to have ign problems.

what i did with mine is, i check the plugs every so often during the dyno. to see for detonation/ etc.

HMTforlife

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blundar &raquo;</TD></TR><TR><TD CLASS="quote">be *very* cautious with a Y5 head, unless that was a typo.

The Y5 flows totally differently and has much lower timing requirements than even a Y8 head. Your compression ratio will ofset this quite a lot. Net result: very difficult to guess timing.

Learn to read plugs because that's the only hope you have w/o money for dyno time.</TD></TR></TABLE>

Yes it is a Y5 head. By lower requirements do you mean it requires less ignition advance than a Y8 head? Right now it's running off a modified Z6 timing/fuel maps and it runs pretty good.

98vtec

blundar,
whats so different about the Y5 head? Is it choked? smaller chamber?

HMTforlife

It's the same casting as the Y8 head, I think he means it flows much differently due to vtec-e.

suspendedHatch

The OBD2 D-series heads are much more efficient than the OBD1 heads so they use much less timing. Don't even start with a Z6 map, it's way too advanced and peaks too high.

The Y5 is actually very similar to the Y8 except that peak VE is at a different spot due to the different cams. But the intake manifolds are identical as well as the head castings. The transmission gearing is different of course.

Start at 12-16 degrees at idle. Mine is a 3 stage VTEC (sort of a Y5/Y8 hybrid). I made max power with only 19 degrees timing advance. Light load cruising RPM should approach 40 degrees and you can run upwards of 18:1 fuel if you have a wideband O2. Middle areas are in the low to mid 20 degrees. As for boost I can't help you. Highest boost I ever got was 101kPa lol. You can safely run quite lean through most of the map. If you get any knock under heavy load you could always douse it with fuel and/or run 91 octane.

Timing will advance with RPM and retard with load. Timing will be low at peak torque and increase outward in all directions (except perhaps with increasing load). These are just very general guidelines of course. What you really need is a load holding dyno so you can find MBT on the fly.

HMTforlife

I have the vacuum side of the map tuned, I just need help on the boost portion now. I do usually run it a bit lean under part-throttle and can get mid 40's mpg on the highway so I'm happy with that. I hear some people are running setups like this with 20 degrees advance under full boost ~17 psi and I am running only 10.5 degrees advance there, so I think it's just way too conservative now. I'll have to do some plug chops I guess but in the meantime advance it a good bit.

98vtec

whats so great about street tuning is you can take all the time in the world and it not cost you a dime besides in gas money.

take your time and advance slowly.