Chuck Schreiber

Thx for the info, I appreciate it!

To be honest with you, I never spent any time paying attention to any of this. Now one day post TBWP, it's all I'm thinking about!

PorKen

0° vs. -12°, two different auto S3s, but roughly the same mods.

Extending the torque output by 600 rpm is like installing a supercharger. +42 RW HP/TQ SAE @ 6250 RPM


Retard = good, yes?


Red '86.5 auto, 150K miles, X-pipe, RMB, -12° retard, 87 octane, S300s Black Edition 1.0 chipset

(STD) (UNC 60F)

PorKen

Who needs a dyno? Followed a stock appearing C5 up a hill in the black car. C5 could not get away.

I couldn't believe I was staying right behind him...then I hit the rev limiter in 2nd, flat shifted to 3rd, and started gaining on him.


Followed him on to the freeway, and still had no problem. He merged onto another freeway; waved as I passed by. Made my day.




Even more awesome is that I was on my way to log the new air filter I'm trying out, so I was recording the 'run'.
(Flat 12.5 AFR, no knocks.) If I'm comparing correctly, it is breathing the same as it did in December weather!
About a 4% improvement, which would put me near 325 rwhp sae or 360 chp! (Stock LS-1 = 350 chp sae.)

Second pic is the definition of minimal exhaust, but it's not that loud with the -12° retard/87 octane.
HeX-pipe into GT resonators. The final H-pipe gives it a warble at full throttle that is just...glorious.

jbrob007

Ken,

Wouldnt that air filter set up suck in a lot of hot air off the engine..? Correct me if I'm wrong, but doesnt the engine like fresh, COLD, air better...?

Joel

PorKen

In a stock engine compartment, yes.

This car doesn't have a radiator shroud, air tubes, airbox, fuel cooler, a/c lines, heater hoses, or a hood seal, so cool air is always flowing back there.



I'm starting to think about some sort of shroud for it, so it could be fed by the air tubes, so I can put one in my (stockish) white car.

Chuck Schreiber

Ken,
Went to Seans yesterday and he adjusted my cam timing along w Richard Kohlers.

On Richards car, Sean set to -6 degrees (1-4) Pass side and -4 degrees (5-8) driver side and he noticed a BIG difference on mid-upper RPM power with NO downside at lower RPM according to his Assometer.

We set the GTS the same and even w my knock sensor issue the difference was significant.
(went from -2 0, to -6 -4 respetively)

Can't wait to get the knock sensor nailed down and pick up even more power!!

dprantl

This was done without any ignition timing or fueling changes? I thought that just changing cam timing and leaving everything else alone would not give much if any improvement?

Dan
'91 928GT S/C 475hp/460lb.ft

Chuck Schreiber

Dan,
I could definately feel it, but yes, I"m sure if you shark tuned along w the changes you could really take advantage of the cam timing.

I also think that w Ken's tool being able to dial the cams in flat out makes the car run better.

Spending time w Sean, the cars that he's dialing in after TBWP jobs are around 6-7 degrees off front one bank to the other. Pretty significant.

PorKen

Retard needs (low restriction) air!

Back to back runs in 3rd on a closed course, conical K&N (w/3.5"-6" bellmouth adapter) vs. open airbox, -12°/87 oct.

Taking the lid off is another few grams/second, so compared to a stock, closed airbox, the difference is huge.


Vacuum is higher with the K&N in certain areas above 3500 rpm (which also tend to correspond to higher airflow), which I can only attribute to higher velocity airflow. There does seem to be more swirl, or something, because I've been able to increase the ignition advance?

Contrary to what you would expect, it runs 'richer' with the K&N, as the airflow vs. rpm relationship is skewed towards airflow.

jbrob007

Ken,

I have the Cam Timing tool... I'll be ordering the "bump stick" shortly. Were gonna set the cam timing on my 5 Speed and Mike's Auto - both cars are 86.5, S300v3.6 chips, cats & stock exhaust with RMB. Where should we set each cam...? -6 degrees (1-4) and -4 degrees (5-8)?

Gettin' kinda antsy to get this done and go for a ride Thanks!

QUOTE=Chuck Schreiber;9563304]Ken,
Went to Seans yesterday and he adjusted my cam timing along w Richard Kohlers.

On Richards car, Sean set to -6 degrees (1-4) Pass side and -4 degrees (5-8) driver side and he noticed a BIG difference on mid-upper RPM power with NO downside at lower RPM according to his Assometer.

We set the GTS the same and even w my knock sensor issue the difference was significant.
(went from -2 0, to -6 -4 respetively)

Can't wait to get the knock sensor nailed down and pick up even more power!![/QUOTE]

PorKen

Those chips are optimized for zero. (-2, 0, cold)


S4-up have closed loop ignition timing with knock sensors and may be able to make use of some retard without tuning. S3s don't.

BC

I will assume that now you will be investigating how you can control the cam advance/retard separately on the exhaust and intake cams.

jbrob007

Damn your quick!! You answered my question in less time than it took me to order the bumpstick

Thanks again...

dprantl

Well that's easy, just slap in some tensioners from a 968

Dan
'91 928GT S/C 475hp/460lb.ft

PorKen

I thought I was on to something...but I guess not.

313 SAE at -2° was the peak, and I have just been losing torque.

It was a bad dyno day, hot, problems with the dyno, tach pickup, etc. Even with all that, it's clear, over -8° doesn't do any more good. Also, the K&N does not make any more power than the stock airbox with the lid off.

Lurnin' is good, and it is making 310 SAE (320 STD) on 87 octane, which is cool, I suppose, but the loss in torque doesn't justify all the extra work of cam timing (months of tuning, my sanity ). There might be a couple MPG gains, it revs easier, blah, blah, but going by power output, the best setting is -8° or less.


Other years may have better results for HP, with larger valves, or? The (my) S3 is apparently stuck at 310±, w/o some more radical improvements.


Now, I'm stuck with two full tanks of 87 to work through, before I can go back to 0°...