mark kibort

Dennis, am i seeing things, or is your driver side exhaust cam lobe, opposite to mine when the indicator boss or mark is pointing up?

ah, never mind, you bounce back and forth with your driver vs passenger sides. that was the passenger side.

mk

mark kibort

is that the 968 stuff????

mk

Bill Ball

20 degrees may sound like a huge error, but without the Porsche tool, when we eyeballed the alignment of the lobes versus a photo or our eyeball estimate of what the cam lobe separation should be, considering the included angles of the valves, we could make arguments a tooth in either direction. The arguments were between one another. If any of us were working alone we could have easily convinced ourselves things were right on.

Even on the pair with the alignment bosses, one of the bosses and been ground down so there was no tip left. It was not nearly so clear as in the shop manual photo.

We tried a variety of ways to improve our eyeball technique, including Mark's suggestion of figuring where the missing boss must have been from a comparable cam, but we kept getting inconsistent results. Again, it was hard to get all 3 of us to agree. I did not like any of these estimates. None of us really did. All of our eyeball estimates were +/- 10 degrees. There's your tooth error.

So, out came the dial gauges. With them, we could determine max lift repeatably within 1 degree unless we made some sort of boo boo.

Here you can see the extension Jim made to get the indicator on the lifter. The area you have to work with to get a shot at the lifter w/o cam interference is rather small, but it worked like a charm.

IcemanG17

Sweet work and pics guys!!!

Dennis your new and improved motor is really gonna be something!!! With the exhaust setup you have and some sharktuning you should be close to a NA 5.0L dyno record!! I think the current record is close to 350whp

Dennis K

Quick update:

Yesterday, I replaced the old cam chains w/ new Iwis standard chains (racing versions were not in stock anywhere for months) and replaced the tensioner pads with new ones. With the old chains & pads, we had measured the lobe separation angle between the intake & exhaust at around 116º. After replacement, the LSA dropped to 113º on both sides, which is exactly what we wanted. It shows how just much of a difference replacing the stretched chains and worn pads can make.

By the way, the specs in the factory manuals show a 114º LSA for S3 cams and 110º for GT cams, so we're right in the ballpark.

BC

Wow.

atb

Pretty marked difference. Will be interesting to see how your motor reacts.
Narrower LSA in very general terms means a little rougher idle and more bottom end? Then again, you've got bigger lobes now than a stock S4 so I guess you get more all around.

Bill Ball

And I will add that Dennis' pads were not terribly worn. The chain groves on the "tight" side were pretty shallow, far less than most people would think indicated replacement, and the "loose " side pads were unworn.

Dennis K

That's right Bill, I forgot to mention that. I should have taken a pic of the old pads.

drnick

do you guys have an update on the installation and running? ive just been driving my car after installing the cams as per jims timing recomendations... will aim to dyno later this week. only touble for me is tha ive installed headers at the same time so i cant tell what has done what. im guessing ive gained 30 bhp total but we will see. the big question in my mind is whether the timing needs altered any further??

Andre Hedrick

Dennis and Bill,

So that what was in the boxes I gave NorCal 928?

Bill Ball

Andre:

You mean the Porsche engine support tools? They were well-used on this project. THANKS!

nick:

Dennis should come in and report, but he has been having too much fun driving his car. It screams. We have done some seat-of-the-pants dyno runs on the local freeway and it feels very strong. Dennis had headers already, and these cams added some power, along with the lightweight lifters . We were going start Sharktuning today, but we still need the early style diagnostic connector cable to do that (on backorder). We plan to get to the dyno in a couple of weeks.

Jim Morton

Nick:

As Bill already mentioned, Dennis' engine is running well. The AFR readings are not too far off and we did use 24# injectors from the get go with these cams/headers/etc.

Given how Dennis' engine runs, I have had the same cam profile ground on a set of GT cores with the narrower lobe centers, all on a shift of the intake cam. I will install these cams into my GTS later this summer. In the mean time, I now have a Sharktuner setup and am working on getting a good handle on using it. As Bill mentioned, we are getting it wired for the 12Pin style diagnostic connector as opposed to the 19P connector sent with the ST. Once past this hurdle, we'll begin tuning in Dennis' engine. From there, I dive into my GTS !

Andre Hedrick

Cool, I have never seen them before and this was a first!

Dennis K

Dr. Nick -

The motor has been installed. Go to this thread for an update (with video):
https://rennlist.com/forums/928-forum/428483-5-0l-track-motor-build-is-finally-done.html

The car runs extremely well. The pull at 5000 rpm seems greater than at 4000 rpm. We're just starting down the road of Sharktuning. As we get further along I'll update the above thread.

Andre -

Many thanks for the engine support stands. Go to the thread I linked above to see more pictures of your donation in action. It made life a lot easier having those pieces.