so it has come to my attention

[quadzjr]

after a few discussions this weekend. Has anybody been able to make good power with the single cam V-tec engine with IT legal mods?

[Ed Funk]

:cool:Hope not!

[quadzjr]

IT was quite dissappointing to watch D16A6 powered car pull me down the backstretch at daytona.. I talked to another single cam vtec runner and his motor is prepped well boyond ours, and is still not as fast as his older CRX.

[mossaidis]

D16z6 here - Not really, though I am not fully prepped. I still need .040, new FD, matched injectors and a full retune with the existing Uberdata or new Hondata. I felt some loss when I had to pull out my CAIv2 but seemed to gain that and more when I shaved the head and did the mild port. I think I'm at 9.5 CR but would like to see 9.7. No whp to share since it's been three years since my last dyno run.

[RexRacer19]

So, what are you thinking is not legal about the motor?

[quadzjr]

I never said anything was not legal about other peoples motors, it seems that the overwhelmeing majority of the cars were faster in a stiraight line. D16Y8 here, have hondata running just slightly modified P28 map.

[bonespec]

Might wanna get that tune checked out then.

Y8 program differs by about 9 degrees ignition timing in the computer, you could be running too little overall ignition timing.

In street trim, A6 CRX will pull away because of 4th and 5th gear ratios, also the weight difference.

CRX 4th .937
92-00 4th .909

CRX 5th .771
92-00 5th .702 except HB/Sol Si models which were .750

[RexRacer19]

I never said anything was not legal about other peoples motors, it seems that the overwhelmeing majority of the cars were faster in a stiraight line. D16Y8 here, have hondata running just slightly modified P28 map.

Ah...you are just trying to sort things out for yourself. I don't know anyone in these parts that has done a full build to have a reference point on your motor, so no help there. :(

[downingracing]

I'm actually very happy with my ITA built D16Z6. Built by Scott Lunder in 2008 - not built to the edge of the rules, reliable was the word I used... I don't remember the specifics of the build, but was happy with the HP/TQ # at the dyno. Haven't had it back to the dyno since the break-in run to see if those #s are up or down. It is tuned on 100oct. at the moment and I've kicked around having it re-tuned on 93 to see if that makes a difference. I'm sure there is a little more power in there and someone more serious could find it.

[quadzjr]

Might wanna get that tune checked out then.

Y8 program differs by about 9 degrees ignition timing in the computer, you could be running too little overall ignition timing.



We tried bumping the spark advance by about 5* from stock at the distributor before the begining of the second race.. It seemed to have a negative effect.:(

[bonespec]

from a tuner friend who knows about this issue all too well


The cam is cut wierd causing ignition timing to be off 9.x degrees, then the P28 basemap everyone runs has 16 degrees base timing and the Y8 crank pulley is indexed at 12 BTDC.

[mossaidis]

^^^ YES! I was biting my tongue - I wanted to say the same but wasn't absolutely sure about the Y8 timing numbers.

quadzjr (http://www.improvedtouring.com/forums/member.php?u=15065) - so, I think you need to keep your stock timing set at the distributor and retard your timing at the ECU back down to 12 degrees.

FYI, my stock Z6 (w/o head shave and w/ open pipes+pulley+cai) dynoed best at the stock 16 degrees - sometimes stock is best, the dyno will never lie.

[bonespec]

also with the Y8 intake, VTEC switchover needs changed to a higher RPM like Honda did. Too low of a switch over and engine will feel lazy.

Z6 OEM switchover is 4800 rpms, 4500-4600 is doable.
Y8 switchover is 5500 rpms, might get away with 5000.

[mossaidis]

Another FYI, lowering your Vtec swtichover isn't always good. I ended up moving mine from 4800 to 5100. Why? Basically... with bigger pipes, you actually end up getting less linear flow into the engine at mid-rpm so having one valve open is better.

Run our engine on a dyno with vtec off... run it again with vtec kicking at 3000 rpm. Lie both whp graphs one on top of the other and where the lines intersect is where your VTEC crossover should occur.

[bonespec]

I'll assume you don't fully understand your VTEC.

Since D16Z6 always opens all four valves, just opens the intake valves farther and longer once engaged.

[quadzjr]

we actually did do a non vtec pull.. not on purpose.. the bolt on the top of the head that plugs and oil pressure port fell out, not allowing V-tec to engage. got a whopping 100 hp.. without it.

[mossaidis]

I'll assume you don't fully understand your VTEC.

Since D16Z6 always opens all four valves, just opens the intake valves farther and longer once engaged.

you're probably very correct - I just don't remember the write up in my factory manual.

[quadzjr]

its definetely a compromise. I would love for it to do both intake and exhaust!