Managing data to track progress

So after some messing about with the new air intake I decided it was time to think about tracking changes over time. The Rotofab intake took about 1hr to fit. Note the nice large cone.

Sounds much nicer with a bit of intake roar now. Some may note the crusty MAF hiding out there. I was hoping this model had the newer LS7 blade maf. But its still the old 2005 85mm LS2 type maf. Of course it must eventually die. But I'm going to use the MAF to give me a bit of info first.

Rotofab installed

A piece of straight 4 inch silicon hose has been ordered to sit where the MAF is now. I want to get all the airflow and torque tables right first before removing the MAF though so I will be failing/moving between Speed Density and MAF airflow models to identify any changes in calculated torque values etc. The summary is in Speed Density the tables are not right. This is because the OEM Speed Density values and tables are not right. I guess its easier to get one column in one table right rather than tables like this one right! There are 450 cells in this table and there are 4 tables like this!

E38 VE Polynomial factors

Also make any modification to Speed Density airflow and the tables all need redoing! Thats because they are static and map engine efficiency based on RPM, Intake pressure, temperature etc. This is also why lazy types just tune MAF airflow models. Thats if they arnt even lazier and just tune the PE table like one tune I saw this week!

All the UK tuner tunes I have seen have been guilty of this at least historically anyway. I suspect some of this is driven by the fact that people think they can get a good tune in 1hr for £250! Ask GM how long it takes them to build a tune for a new application. Im certain its months.

Anyway there is a very good forum post on EFILive regarding the engine torque tables which are crucial in managing communications with the TCM.
See here https://forum.efilive.com/showthread.php?18710-Improving-shifts-via-the-ECM

E38 Torque Model Tables

The table above is the one mentioned in the article and allows the engine to calculate torque output based on a number of factors similar in concept to how Speed Density airflows are calculated.

The plan is to visit Mr Wright at Surrey Rolling Road after most mods to get a good view of things. But rather than relying on a trip there every week to guage progress its possible to use EFILive logging to get information which is just as good depending on how accurate airflow models are. (Hence the discussion above about keeping the MAF in place until the Speed Density airflows match the data from the MAF).

So what data can we use? Well basically we can use measured and calculated grams of air per cylinder for a torque proxy and grams of air per second for a bhp proxy.

We can also use calculated torque values from the MAF and/or Speed Density (The topic of the torque table above) This is the main reason to keep the MAF for now. So I can get good torque calculations. Once Speed Density is giving me similar/same values I will retire the MAF.

As a plus EFILive Scan Tool allows me to export the data to CSV and therefore Excel or Access. This should allow me to do conditional evaluations of the data and tell me what spark timing at what RPM and load point gives the best calculated torque value. I was going to do the same thing but with g/cyl to proxy torque, but Jessie Bubb said he uses calculated torque while we were chatting at PRI this year. (He mentioned he even has some sort of Calc PID, Ill try and pry it off him to see how its supposed to work)

So anyway, what does one of these CSV files look like in chart form? Ok this is from the first Dyno day at SRR.

Log generated Dyno Graph (fwhp)

Does it look even remotely like the Dyno chat from SRR in the previous post? Yep. The data set at the bottom is not synced nicely. So cleaning that up would help. Also just querying the data is going to be more helpful and accurate. If I can figure out Microsoft Access I can upload each log as a CSV with different timing values in it and query out the highest calculated torque at each load point vs spark timing. Worse case picking out points and looking through each CSV import in Excel should allow a manual way of doing this.

So that basically is how I will be monitoring and tracking changes of modifications and ensuring spark timing is optimal. If these values increase, power should also increase by the same amount. So I can look at percentage gains to get the relative merits of each change. First up will be to log the Rotofab intake and see what that achieved. Hopefully that will be the next topic in this Blog.

Maloo Baseline and some dyno lessons for me

Thanks to Charley at Surrey Rolling Road I have a baseline.

This is in line with Oz numbers for a stock standard LS3 Auto, but pretty woeful none the less.

Maloo R8 SV A6 Baseline

Fuelling was consistently about 0.5 AFR out, so if I was braindead I could just add 4% to the commanded PE table and it would be about right.

But I try to avoid braindeath and instead will go the long way round, which should result in more accurate logging as well as better performance and correct tune values in the long run.

Afterall, if the airflow model is wrong from GM, then its going to mean timing values are out, not just fuelling.

Here is the log file from 2 runs on the dyno. See anything interesting?

Dyno runs

So a few things spring to my mind. First; 16.5* of timing seems very low. Sure there was a tick of KR (Knock Retard) but so little its not worth mentioning. Also max timing is only 18* in any case. So I need to check the tune and see what is being commanded.

Second thing I note is that manifold kPa is only 95, earlier in the run it was 99. So thats a definite intake restriction right there. Now considering the SV model has "bi-modal" intake for better airflow, this is particularly woeful. There is pretty much a solid 3-4% lost right there.

Final thing of partial note is long term fuel trims differ between banks. Now looking at the trims over time I can see they are similar but never match, this suggests injectors, engine, exhaust etc differ enough that fuelling needs to vary across banks. Max trims are 4% which is well within the ability of short term trims. So long terms will go as is my practice and short terms will remain. I can use short terms to adjust injectors to give one bank more than the other in closed loop and even adjust the tune to give one side more in open loop too. I did this to slightly richen up cylinder 7 which in the LS series is often slated to run slightly lean. (eg Corvette Foum post)

So with the tune up and the logging tool up at the same time you can enable highlighting. What this does is show you where in the tune you are at that point in the log. From this you can see that below in the graphic the log says I have 18.5* timing, but the tune says I should have 22! 

So where is the missing 3.5!? I did not log all the spark modifiers, but Id suggest that if its not burst knock paying a visit, then its likely to be some torque management playing havoc. Especially as the front wheels were not turning and the ECU/BCM may consider this abuse.

Highlighting logs and tune EFILive

In fact this is quite likely as it threw a few codes to do with the ABS system and a myriad of other things at the time. All of which were reset with a power cycle and scan tool after the dyno.

So there we go a baseline and some lessons for me in where to find more power.

You may ask why GM delivers a vehicle that doesn't achieve full power potential from new.  I would agree, its a bit sad. But then I wouldn't have a hobby! 

A cursory review of Oz forums shows that a common mod in the VF which gains best value is an intake and a tune. Strangely I have an intake (See last couple of posts). I also have EFILive! Popping an exhaust on doesnt seem to be necessary at close to stock power levels. I measured the exhaust and I am pretty sure it sports a 2.5" from the factory. This is far better than the chunderous 2.25" mess that they used to come with and explains why the Oz guys just do intake and tune. Some good results from that are had too.

So my mission will be to address the issues as follows;

1. Gain 4 or so kPa from a new intake (Rotofab Chevy SS 2014 aka VF model)
2. Clean up airflow model so that commanded fuelling equals delivered fuelling
3. Figure out whats taking the timing out and address the cause

What am I expecting to gain? Good question. Id be pleased with 10% which is more than some guys get from fitting a cam! Though of course their baseline was with tune. So that will be my next mission post tune.

The ultimate goal is to deliver more power than a supercharged GTS with a lighter weight and better fuel economy.

On that topic Im surprised that the Maloo drinks far more than the E1 with the LS7 in it. Its reading 17mpg average! Shocking. The E1 says 26, but really its more like 23 due to injector scaling. Still thats almost 50% more. So really my number 4 aim above is to increase fuel efficiency, which by using less fuel under power enrichment as well as freeing up the intake should be a natural consequence.

Time flies

Time flies, it seems like only a few months back I bought the Camaro. Well here we are 3 years later and its sold.

Actually it sold a few months ago to a good keen bloke from up North. It ended up being pretty aggressive. Mainly from the 3600 stall converter. Stab the throttle and you were rewarded with instant wheel spin, this would occur at most road speeds. Except perhaps on the motorway.

Chris the buyer, said it was too violent and aggressive. Id call that "working as designed".

So it was a sad sale. But it had to go to make way for this item.

100% tax deductible commercial vehicle. Which just so happens to have a Corvette LS3 V8 in it. Same basic config as the Camaro, RWD Automatic V8. Its an HSV R8 SV Maloo.

Some fancy features with heads up display etc. I already have a set of Winter tyres as it will be doing loads of miles. It arrived into the county in September, but sadly its now not going to be ready until mid November! A bit frustrating, but at least Im not managing all the to and fro about the place to get it certified and on the road.

So I wonder how long this will remain stock for?

Oh dear, a new camshaft that just coincidentally arrived around the time of the Maloo. Best I keep the two apart for a while. The Maloo has a 3 year warranty, so no point throwing that away too quickly.

Though this part looks a little more mod friendly..

The filter is HUGE, I learnt my lesson with the VXR8 which was that filter area counts as power goes up. Should be no problems with the plans on the table for the Maloo.

So ok, Ill come clean. Current plans are:

1. Rotofab 2014 SS Intake
2. Pacemaker 1-7/8 long tubes with ceramic coating into dual 3" exhaust
3. Comp custom LXL lobe Cam for durability
4. Comp conical valve springs

That will be it at that point, not looking to go too crazy. Though crazy if it does happen may consist of;

1. LS7 Ported intake
2. RHS Small bore LS7 Pro Elite heads 
3. 1.8 ratio Shaft rockers

Not planning on FIsting the engine. Too much aggravation. Solution would be to start afresh and do it properly, not the knock limited bolt on kits most use.

Alternately I can put the engine from the VXR8 into the Maloo. To be honest that's probably the most "sensible" longer term plan.