F.I. Timing map

[SSpdDmon]

So, I made this as a starter high octane timing map for a stock internals '99 running ~7psi through a D1SC. Thought I'd share. Any feedback is welcome.

[Redline Motorsports]

Looks a bit aggressive for a 10 psig motor on pump gas. You can run a decent amount of timing down low at WOT as enough boost hasn't built yet but it needs to taper a bit as you head towards peak hp.

I think timing should be closer to 20-21 max at peak.

Howard

[SSpdDmon]

7psi on 93 - stock internals. Aggressive as in too much or too little timing?

[Redline Motorsports]

7psi on 93 - stock internals. Aggressive as in too much or too little timing?

I think its a bit too much timing. Since a centrifigal supercharger builds boost linear to rpm, you don't have as much boost in the lower rpms. Because of this you can be more aggressive at lower loads but need to ramp back the timing as boost increases.

When we do PC Z06's, they don't really make any measurable boost until about 4K. I use a NA timing (our timing table ) until we hit 4K and then start toning it back. We only use about 14 degrees on 5 psig on these motors but run as much as 28 down low.

Howard

[SSpdDmon]

Hmmm...I really need to get on a dyno.

[Redline Motorsports]

Hmmm...I really need to get on a dyno.

Send me a e-mail and I can send you a file of a timing table we have used on many PC cars. Of course every car is a bit different but you can get the general idea.

[SSpdDmon]

PM'd email...

Next issue = fuel pressure drops to ~50psi under WOT and a low of ~48psi at 6Krpm. Fudging the fuel tables, I can keep the afr at 11.8~12.0 until about 5800rpm. Then, it'll hit mid 12's. The paperwork from the previous owner indicates a Walbro 355 pump & hotwire kit was installed (I believe it's the Racetronix plug & play system). My lights flicker under any throttle and occasionally at idle. Thoughts? I can't seem to find this electrical gremlin.

[Redline Motorsports]

PM'd email...

Next issue = fuel pressure drops to ~50psi under WOT and a low of ~48psi at 6Krpm. Fudging the fuel tables, I can keep the afr at 11.8~12.0 until about 5800rpm. Then, it'll hit mid 12's. The paperwork from the previous owner indicates a Walbro 355 pump & hotwire kit was installed (I believe it's the Racetronix plug & play system). My lights flicker under any throttle and occasionally at idle. Thoughts? I can't seem to find this electrical gremlin.

Varying fuel pressure definately needs to be addressed! A stock engine on 7 psig shouldn't be running out of fuel with that pump unless the pump is bad or the hot wire kit isn't working. Maybe the alternater is on the way out.

[SSpdDmon]

Varying fuel pressure definately needs to be addressed! A stock engine on 7 psig shouldn't be running out of fuel with that pump unless the pump is bad or the hot wire kit isn't working. Maybe the alternater is on the way out.

Logged GM.VOLTS and it bounces around between 13.6 and 14.2 volts. I'm wondering if the hotwire kit isn't working right.?.?.?

[SSpdDmon]

Hmmm...someone just made an interesting point. If you boost your intake say 7psi, doesn't that mean you're effectively reducing your fuel pressure by that much because the fuel now fights that pressure....thinking along the same lines of why the IFR table is slanted, where additional vacuum actually improves the flow of the injectors???? Maybe my pressure drop is normal for a stock fuel system with an upgraded pump and injectors only???