Tuning timing on the E38?

[ringram]

How are you guys tuning timing with no bidirectional or realtime flexibility?

Do you run a baseline in a few key area's then make some changes and rerun noting any +ve changes, alter and repeat? Id be interested to know how you go about optimising the timing with the least amount of effort.

[Doc]

Gtech RR Pro w/ the serial out.

[Redline Motorsports]

I usually start out with a "reasonable" base timing table and make a pull look for knock and keep adding. If I add more timing and no chnage was observed in HP, I go back to where I was. I guess there is no real mystery at this point as to what certain LSX setups like for timing. This is also assuming that fueling is close to be in line as well as knock countermeasures.

[ringram]

Ok thats cool for WOT, but what about the rest of the timing table for part throttle operations?

[The Alchemist]

I find on road throttle response useful as a guide for timing on one of these. It is difficult though, with no BIDI its a real pain .....
Burst knock is also extremely invasive with 8 deg being pulled with even light throttle applications let alone nailing it. I knock this back heaps as it causes a noticible jerky drop in power and ruins the feel. I find these engines can run more top end timing than an LS1 at around 25 deg. We have crap fuel here in NZ.
I found that with the factory maps before any tuning the engine could be made to audibly pink going up steep hills. I pulled over 10 degs below 2000rpm to stop it....

Mike

[The Alchemist]

Today used the pen and note paper method which yeilded excellant results. Loaded engine at set rpm, thottle at set rpm and load cell constant, noted tractive effort with writing stick and papyrus :)
Reflashed with lower spark timing and repeat operation until you see a tractive effort drop. A bit more time consuming but gave me a good idea of where the timing was going by testing at rpm points 600rpm apart. Interpolate the rest and you're done...or pretty damn close anyway.

[ringram]

Exactly what I was thinking, well Id use Excel. With the road runner I used area blending which works real well to dial in the key area's. Perhaps choose key points & record tractive effort over a load of points. Alter and repeat. Comparing results and altering until you have a fair go at it, which it sounds like you did. As you say it can make a massive difference to part throttle. Anyone who only tunes WOT is missing out on something akin to the difference between night and day. I was just wondering if there were any more scientific approaches to the process at present. Bidirectional controlls would be excellent as you could just note the final values in one extended load session.

[Redline Motorsports]

Exactly what I was thinking, well Id use Excel. With the road runner I used area blending which works real well to dial in the key area's. Perhaps choose key points & record tractive effort over a load of points. Alter and repeat. Comparing results and altering until you have a fair go at it, which it sounds like you did. As you say it can make a massive difference to part throttle. Anyone who only tunes WOT is missing out on something akin to the difference between night and day. I was just wondering if there were any more scientific approaches to the process at present. Bidirectional controlls would be excellent as you could just note the final values in one extended load session.

I agree on timing changes below WOT load values. Anyone can tune a car at WOT.

Finding MBT is the key to cruise and midrange performance. The closer you can run to MBT the better the throttle response will be as well as better fuel economy.

You have to be careful with the data you collect under "dyno load" as it can vary as heat is built and picked up by both IAT and ECT. Believe it or not but I have been pretty sucessful dialing in MBT on the street until we can get some real live tuning capability.

Another trick is to make a table that shows which cells are the cells the PCM pulls from at a variety of engine and driving loads. Usually between 1800-3500 from .32-.70 grams/cylinder is a sweet spot to optimize. Past that and your really reaching into WOT.

HT

[The Alchemist]

I agree on timing changes below WOT load values. Anyone can tune a car at WOT.

Finding MBT is the key to cruise and midrange performance. The closer you can run to MBT the better the throttle response will be as well as better fuel economy.

HT

couldn't be put better :D

[cmitchell17]

Could you put cruise control on on the highway going 65 or 70. Then used the BIDI and start with really low timing and keep moving up untill your throttle position gets the lowest?

[The Alchemist]

BIDI doesn't work on the E38.....thats the whole problem mate