OZ951

I thought I may as well post this up for reference. This chart is a boost run at 15 PSI which is all I ran for the cars first session back at the track a couple of weeks ago. The dyno runs were actually done the morning that I left to go to the track. I had not touched the fuel map for boost conditions and it quickly showed that I was very rich initially, the fuel curve as it is on the graph was after winding back the fuel between 10-20% in the boost zones. The rather large cut backs in fuel are no doubt a consequence of the fact that I was running a lower boost level than the Guru chips were programmed for. Anyways the fuel curve is still pretty tragic (as if you couldnt tell) and I didnt want to spend too much time & effort refining it as I will be putting on the Lindsey fuel rail in a week or so and changing fuel pressure which will necessitate a trip back to the dyno to tweak the fuel map.

****ty fuel curve aside I was pleased with the smooth and broad torque curve.

As a side note I spent a few hours road testing/tuning Dwayne Williams 951 with him and his WB O2 this weekend. We found that we had to cut his fuel back about 24% as well (also has Guri chip/MAP and TO4B), he also was running 15PSI on his recently reassembled engine.

Last thing, I got a couple of really nice pics from TWS a couple of weeks ago, they are here (at the bottom of the page) Gallery

Mike S

What kind of turbo is that? Why does the boost come on so late? It looks like you aren't getting full boost until 4200rpm.

Sami951

I find it interesting your car makes over 250lbft of torque even before full boost ... nice!

Is this the A/F you came up with when you tuned the MAP zones with the narrow band sensor?

toddk911

Does Danno know you are not running a stock turbo??? As that is probably why they are 20% rich. Newer TO4's would be more effient and not need as much fuel as stock turbos.

I would guess with cleaned up a/f another 15-25 hp/tq. Or just run more boost At your current a/f and with those 75lb injectors, I would think 18 psi would be totally safe.

fast951

I personally would not track the car with such "all-over" Air Fuel Ratio. Between 3500 and 4200RPM you are lean.. and you can tell the rest.

DO NOT increase boost pressure till you sort this out...

What size turbo do you have... Way too much lag!! What kind of boost control do you have.

Once the AFR is cleaned up, you will make more HP/TQ...

OZ951

The turbo is a T04E, boost does peak later than a stock turbo. I forgot to mention the overlaid boost curve, that is from the datalog that I did during the boost run. The overlaid data (boost/rpm/TPS) is only approximated, ie I stretched the datalog info over the dyno chart based on RPM and TPS. With that said, the boost still does peak later although it is often more like 4000 than 4200 rpm. The other factor there is that I am still working to optimise the AVCR to control boost. In fact I was still playing with the duty cycle on the way to the dyno and opted to leave it at a safe (non overboosting) duty cycle rather than a spiky but quick risetime boost level.

Basically I was still trying to sort out a lot of last minute stuff to get the car ready for the track and the double tranny swap the day before didn't help with the amount of time I had available to refine things, grrr end of bitch.

OZ951

On the way to TWS I added more fuel to the lean spot at 3600 rpm as it was the zone that concerned me. Using the narrow band AFR I was able to verify that I had eliminated the lean spot during the transition to boost. I also leaned up the rich top end a little further but did not want to over do that until I can get it back on teh dyno for some accurate adjustments.

As for increasing boost pressure, that will come when I am happy that I have good boost control established and can verify the fuel mixtures accurately. Its not my way to push the car hard until I am confident that it is sorted out, incremental steps are good.

Sami - the tuning that I referred to in my earlier post was primarily the off boost zones of the map.

Todd - the reason for being 20% (more actually) rich is more likely to be related to the fact that I was not running 17-18PSI

Mike S

Sorry....should have been more specific....do you know what kind of wheel/trim you have on that turbo?