dyno results
Thread Starter
Rennlist Member
Joined: Mar 2004
Posts: 2,262
Likes: 47
From: Ohio
dyno results
I just had the race car dynoed today on a dyno jet 248 and rwhp is at 196 and 202 T. I seem to have an issue where the HP drops about 12-15hp between 5500-5800 rpm and then returns to it's previous level. Any ideas why? I have dyno runs from 2008 on the same dyno and don't see this drop.
Thanks,
Thanks,
Rennlist Member
Joined: Nov 2006
Posts: 2,079
Likes: 7
From: Waldorf, MD
Yes, 5500 RPM is where the variocam advances timing again. It's also that way from idle-1500 RPM. Unfortunately I don't think the dyno chart will give any usable information on the lower RPM range.
Trending Topics
Nordschleife Master
Joined: May 2004
Posts: 6,446
Likes: 95
From: Altered States of America (B'ham)
Mike sent me the dyno and asked me to post, see below.
Mike, I am guessing that your timing belt is off by one tooth. This happened to me after a rebuild a few years ago and the dyno chart is very similar. After dealing with the misalignment, that 10+ hp dip went away. I'm pretty sure that I posted that dyno on this forum, but I don't have time to search at the moment.
Mike, I am guessing that your timing belt is off by one tooth. This happened to me after a rebuild a few years ago and the dyno chart is very similar. After dealing with the misalignment, that 10+ hp dip went away. I'm pretty sure that I posted that dyno on this forum, but I don't have time to search at the moment.
Last edited by Lemming; May 9, 2012 at 07:12 PM.
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
Porsche Reveals Coupe Variant of the Electric Cayenne With a Fresh Look
Verdad Gallardo
10 Porsche Colors That Have More Personality Than Most People
Verdad Gallardo
Guntherwerks' Final Speedster Creation Is the Ultimate Porsche Restomod
Verdad Gallardo
10 Reasons I Hate Going to the Porsche Dealership (& the 1 Reason I Stay)
Joe Kucinski
Porsche Shakes Up The Nürburgring Lap Record Table Once Again
Verdad Gallardo
6 Ways the Porsche 911 GT3 S/C Redefines Performance
Joe Kucinski
10 Wildest Homologation Specials Porsche Ever Sold
Verdad Gallardo
Super Rare RUF BTR III Comes Out of Hibernation, Looking For a New Home
Verdad Gallardo
10 Porsche Opinions That Can Start a Fight
Joe Kucinski
Rennlist Member
Joined: Nov 2006
Posts: 2,079
Likes: 7
From: Waldorf, MD
Well, that would explain the HP dip then, as the timing advances from the variocam the DME is compensating for the timing off by 6* or so... For a bone-stock 968 I would expect to see ~200hp at the wheels.
Nordschleife Master
Joined: May 2004
Posts: 6,446
Likes: 95
From: Altered States of America (B'ham)
Mike, here is what I consider a "normal" 968 dyno on the same dyno model. This is from back in 2008. Car was chipped, with header and mostly open pipe.
Last edited by Lemming; May 9, 2012 at 03:59 PM.
Nordschleife Master
Joined: May 2004
Posts: 6,446
Likes: 95
From: Altered States of America (B'ham)
Mike, I may have been hasty on my "1 tooth off" diagnosis. When I got home I found the dyno (mustang, so lower numbers) that shows the effect of being 1 tooth off. As you can see, the effect on the HP and torque curves is much longer lasting.
Nordschleife Master
Joined: May 2004
Posts: 6,446
Likes: 95
From: Altered States of America (B'ham)
Here is an example of my old engine #2. As you can see, it has a dip at nearly the same rpm range as yours. We never determined why this occurred, but I'm guessing that it was timing, just not one tooth off.
Thread Starter
Rennlist Member
Joined: Mar 2004
Posts: 2,262
Likes: 47
From: Ohio
We have never really "tuned" the engine for max hp/t. I am in a hp/weight class and at these level i will be about 40lbs heavy. If the power comes up some I should be right at my min weight. All dyno's are different and my last dyno was about 207t and 200 hp just 1 month ago.