Marc Shaw

Why does any thread with the mention of "chip" always seem to end up heading in the same direction??

Marc

Newbium

"Why does any thread with the mention of "chip" always seem to end up heading in the same direction??"


It's just one of those cosmic mysteries that can't be answered.....

Geoffrey

"Right, which again supports my premise that tweaking the AFR is a total waste for a stock engine!"

That simply is not true. Why run an engine any richer than you need to? Doing so is not only a total waste of fuel, but in my opinion, it means that you have not properly tuned the engine.

dougn

can you advance the timing more if you run a richer air/fuel?

Geoffrey

The answer is "it depends" For what we are talking about here, no, running the engine richer does not allow you to advance the ignition timing.

I have had some engines that have been ignition angle sensitive and when turbocharged have had such a poor engine design or have had poorly selected components that I have been able to run a richer mixture so the engine doesn't detonate at reasonable ignition timing. I would say these were not ideal cases.

NineMeister

Probably because most people simply make do with the one in their ECU, whereas others insist on carrying a spare on their shoulder..

Red rooster

Marc,
I tell myself every time not to get involved ! This WILL be my 2007 resolution.

Snowing out there ? We are in for a Heat wave ( + 12 C ) !! That will make the boys in Florida jealous - well maybe not !

Geoff

fstockcarrera

The commonality is an abrasive pompous *** who adds little to the discussion.

However some of us are searching for the extra 5%-7% + that may be gained with tuning alone. Now Where is the Ignore button.

Lorenfb

"However some of us are searching for the extra 5%-7% + that may be gained with tuning alone."

Right, and some will believe any amount of hyperbole without supportive data, as performance
is always an easy sell! Just "drop the line" and "reel 'em in".

Rennlist "stands" above other forums in that it provides its members realistic
info to make intelligent decisions whether for DIY repairs or for purchases.
Rennlist members range from very knowledgeable Porsche owners to those
that have very limited automotive backgrounds. So, is it unreasonable to ask
that members be provided comprehensive data which support marketing
claims? That's one of the many functions of a forum, i.e. providing its members
the ability to learn and "expose" the issues.

"The conculusion is that air fuel ratio does not have a material effect on overall power within a fairly wide range."

See, with the above statement we have from a tuner, we've basically clarified
the issue of whether tweaking the AFR via a custom chip has any merit,
i.e. none for a stock engine! The thread has been beneficial even though some
were concerned about its direction.

Geoffrey

"See, with the above statement we have from a tuner, we've basically clarified
the issue of whether tweaking the AFR via a custom chip has any merit,
i.e. none for a stock engine! The thread has been beneficial even though some
were concerned about its direction."

Loren, I think you are thinking one dimensionally. I agree that as long as the engine is operating within the range of say 12.5-13.5:1 (or there abouts), you will see little power gain from changing air fuel ratios. Based on the Report 186 it suggests that the engine should output within 12.35hp (5% of 247) of peak power. So, you do have 12.35hp to gain, although in practice with the 911 engine I have seen more like 3rwhp gained or lossed which is minimal and not material on the street (in my opinion). However, you do gain in fuel economy and I believe that to have merit. You gain in a reduction of carbon on the inside of the engine which has merit especially in the 911 engine where the engine has short rods and the pistons rock excessively. When carbon builds up it reduces the piston to cylinder clearance and begins to score the pistons between the top compression ring and the top of the piston. While we are focused on performance, there are other considerations that are made that will improve the overall package. I believe that a good tuner will think about these things. Further, in Bob's case where he races in a class where drivers are separated by .01 of a second, 3hp may be the difference between 1st and 2nd. I guess I believe that anything worthwhile doing is worth doing right which means optimizing air fuel ratios for each engine whether you gain hp or not.

Larry Herman

Bob's only separated by .01 seconds when he's just cruising around. When he's in the zone, the gap grows considerably (but I know that you know that).

Geoffrey

"When he's in the zone, the gap grows considerably (but I know that you know that)."

Been on the wrong side of the gap huh???

Larry Herman

Not when we raced Carreras. Just ask Bob! Of course I do remember one April Lime Rock race when I had 5 track days that spring and Bob had 25! Needless to say who was quicker that weekend.

Geoffrey

Yep, and I remember watching Bob school the field at LRP in the rain. He qualified 5 seconds a lap faster than the next car...in the rain..and had the FTD over GT3 Cups. He would have won the sprint race if the Marshalls hadn't determine that he jumped the start (from the pole however that can happen???) and given him a stop and go penalty. It was later found that they did that because they enjoyed watching him slice through the field. He finished 8 seconds back and if it were 2 laps longer he would have passed the leader.

DrJupeman

Here's Bob during that race. Ah, the big wing days...