PorKen

Fred - I am probably biased, but I think the S3 cams are the best of the lot.

Your GTS/S4 setup looks to be better than the stock S4. More intake duration can mean broader peaks, with less knock potential, AFAIK.
It's too bad you don't have a dyno available. It really helps see what is going on - if you can get consistent dyno results.

Once I am done with chip tuning, I would like to put some S3 or Colin cams in my '88.


I am not using a ST, so I don't know which particular cylinder has a knock, just that a knock has been detected.
(I am logging the EZ knock output, with a code patch.)

Without testing one, I will probably knock 2-3° off of the WOT advance.

24# will be a requirement. Along with (-3° or) -4° cam retard.

Bill Ball

Hi Ken:

Neat stuff. Just to make sure I understand your dyno chart above...

Are the blue, green and red lines with the same hardware (X-pipe, injectors etc.), just differences in cam timing, fuel and ignition mapping? Maybe you already specified that. Sorry if I missed it.

Amazing work, especially w/o using a Sharktuner.

PorKen

Bill - I edited post above to show the overview of changes per graph.


Red is cam timing, new programming and tuning, past X-pipe and 24# for blue.

Red line has a couple knocks in the 3000s, but was otherwise knock free.


Note there are some advantages to not being limited to what can be done with a ST.

FredR

Ken,

Do you or any of the chaps on this list have any notional idea of what octane improvement is gained by throwing a jar of STP octane boost into a tank of 95 [89 your gasoline?] octane? The chaps in Dubai can get their super 98 brew but in Oman we do not have the luxury.

I note with interest your comment about not being able to run 89- presumably that is with your advanced state of tune. My work here suggests that stock programming struggles to run our 95 witch-**** brew.

Regards

Fred

jcorenman

I generally don't like to to post dissenting opinions in other folks' threads, but since you asked...
This is our '88 S4 (#413), stock everything except x-pipe with cats (19# injectors, cams at zero).
And Sharktuned, conservatively, for 91-octane: https://rennlist.com/forums/10465564-post54.html

PorKen

I don't recall asking, and I wasn't 'knocking' the ST, which I think is a great tool for regular folks.

I was referring more to variables, maps and code that are not exposed in the ST.


You'll note that my 006 X-pipe graph, is about the same as your baseline with X-pipe.

I have only just started tuning 'the hard way'. Hopefully there is more to be had, consistently.

PorKen

FWIW, the 020 graph had terrible fueling, because as well as the cam timing I was testing some new code.
High 11 AFRs, except for the jolt where the HP peak is.

When I went to fix it, I made a rookie assembly language error and made it way too lean (stupid base 16, 0-9 A-F).
By that time, the dyno guys wanted to go to lunch, and I had my cam timing results anyway.

Anyhu, 310 rwhp should be easy enough to get to.

hans14914

So, are 24lb injectors the right size for the S4 cams and exhaust, or would you recommend ~30lbs?

PorKen

I am logging >90% duty at 5700 rpm with 24#, ~12.5 AFR, half-rate off.
(1/2 rate is only a few % reduction and is a unnecessary complication, for me.).

Since the S4 seems to like it on the rich side, I kind of wish I had put in 30#.


Looking at Jim's S4 graph and the results of this past dyno, I wonder if I may have gone the wrong direction with the cam retard.
If I can get around 310 and keep the monster first torque peak, cams at zero is fine with me.
I would sacrifice some of the big torque for more HP, if it was worth it.

I am going to reset the cams, keep the mixture fat (<12.5), and dyno again with 92 octane.


It will be a good experiment, but mainly, I have to crush (or roughly match) Jim's results.

BC

And then put in 50% e85 in the tank and dyno to show people that even with a half of a tank of the spruce juice that you raise the knock threshold to "none" and you can advance away?

MjRocket

Ugh!.. On your recommendation I just bought 24# injectors... Back to the drawing board.

Speedtoys

...IF you have the capacity to add 15% more fuel to your engine to meet your mixture target, sure.

If someone is on 19s, no. If they are on 24s...marginal, maybe.

BC

Correct. 24s we're not enough on an 86. I went to 36 lb

Speedtoys

And on boost with 50% liquor in the tank, 36's were not up to the job either.

PorKen

Back to cam zero...runs better, feels stronger, logs as faster...on 92 octane.

Not sure how I always get caught up in playing with the cam timing.
I'm going to blame Hilton.


Anyhu, during the hours of drilling PKT brackets, I 'saw' what an ideal WOT table should look like.
One that would automatically compensate for weather, gearing, weight, terrain (hills), etc.

WOT programming can essentially be done in a 'flat', RPM only table, because there is no throttle restriction.
Trouble is, weather, etc. change the MAF to RPM relationship, pulling the AFR up or down.
Stock maps have part throttle data mixed in so WOT AFRs are often erratic.

At full throttle, airflow and ignition are essentially fixed by RPM according to the cams and intake.
Weather etc. change the percentage up or down over the whole range, but the curve, RPM to RPM, stays pretty much the same.
EG. colder air makes MAF volts higher at the same RPM, so the map should compensate by returning a reduced value at that RPM.
EG. dyno roller weighs less than the car = less MAF at street tuned RPM = lean AFR, map needs richer.


I already had made a completely new (16-bit) base MAF table for WOT, so all I had to do was make a progressive slope from low MAF to high MAF.
The WOT table is overlaid over this base table as normal. To make adjustments, all I have to do is edit a single value in the WOT table.

Note that it is read diagonally, from upper right to lower left, as MAF and RPM values go up.
The upper left and lower right areas are never read.


I am still tuning the individual RPMs, but fueling is now very stable (like my S3s), even in the 5600-6000 range.
I guessed on the slope, but even as-is, the AFR change from gear to gear is minimal.
I am going to apply this to the EZ WOT map, next.


While setting this up, I realized that I had done this in the upper RPM ranges on my S3 chips without understanding why it worked.
My S3 chips are super consistent. Now I know why, specifically.

WOT overlayed

base slope w/o WOT