Lagavulin

11 psi, stock block, Ott x-pipe, dual mandrel 2.5" exhaust.

The run is what it is, period. Keep reading though if you want to hear post-run observations/critiques/excuses. I know they'll sound like excuses, but nonetheless, I'm trying to be objective.

I am a bit disappointed as I was expecting more as my calcs said I should make around 530 rwhp with 11 psi of boost at 6400 RPM with my Ott x-pipe and new dual mandrel 2.5" exhaust. What (..possibly) happened?

The car was dyno-ed at a Porsche dealership in conjunction with the Chicago PCA Club, lots of nice cars there! The next highest dyno run was by a By-Design modified 996 which put out 289 rwhp. Needless to say, the other Porsche owners were very impressed by the 928's numbers.

Well, when I got home I looked at the chart again after some of the shock wore off, the first thing I noticed was that the run ended at 5900 RPM. Of course, that's my fault, but how could I do such a stupid thing? Well, I failed to mention to the operator who drove the car on the dyno to take it to 6500 RPM; he was evidently being conservative and cut the run off before the perceived 6000 RPM redline indicated on the tach. Doh!; my fault for not communicating.

The last item is that the air/fuel ratio was rich as it stayed at 11.5 for most of the run, and it popped up to 12.1 right at the very end; my fault again for not tuning better.

With that said, my/our goal is to optimize the car for 11 psi of boost, nothing more, as that boost level is pretty much the max for a 10:1 cr engine. So, I'm thinking there will be one more dyno run this year before winter puts the cars up for hibernation.

First and foremost, we've got to get a better fuel curve and get it as close as possible to 12.5 throughout the entire run. Secondly, take the engine to 6500 RPM! That shouldn't be a problem as the local dyno lets the owners operate their car during the run, and make no mistake, I will be bouncing it off the rev limiter to end the run!

The results, for better or worse, will be posted for all to see/critique.

sweanders

Time to change the sig?

Impressive numbers, I want one of those kits from Tim..

Hmm.. Need to pile up some money first..

sweanders

Btw, isn't 289hp pretty low for a 996? Did they all stop at 6000 rpm's?

ErnestSw

Lag,
It appears, to my feeble brain, that you have NOTHING to make excuses for. Those are impressive numbers by anyone's standards.

Tim Murphy

I should send the dyno operator a thank you note for pulling out of the gas so I can keep the top honors for just a bit longer.

Good job!! I wish I could have been there to see the faces of the 911 guys when the numbers came up. I wonder if anyone from that group posts to the 911/993 boards? It would be interesting to listen in on what they have to say about your numbers.

Gretch

Hoo Ha!!!!!

Bring it on TIM, my wrenches are at the ready!!!!!!!!!!!!!!

BTW, Exactly what do you call your kit, just so I am using an approved reference in my signature.................

G

jim morehouse

Murph and Tim,
Just curious about Murph's car vs the kit. I think I remember reading that the kit is 7 psi, right? Is there any reason for the kit not to be at 11psi? Significant mods required? Just a conservative 'safety' factor?

thanks and congrats to both of you,

Jim

Gretch

"Murph" and Tim are the same person, (Tim Murphy) You prolly ment to adress Lag.......

Good question............bet Tim has an informative answer..............

SL8GT

Jeez, Lags!

You got nothing to be "sorry" for! Awesome numbers. Period.

Not too many cars around you can't spank.

And after tweaking the a/f ratio, you'll have better numbers!

Curious: does the dual 2.5" flow enough or would you be better off with dual 3"?

Congrats!

DerSchlechtSpecht

Wow, I should definatly get a 928.

Christian

Tim Murphy

Well, the kit is actually setup to produce 8psi of intercooled boost. Lag's car has become somewhat of a test mule car by his own choice. You see, when we did Lag's car he was only supposed to get 8psi and when we ran the car for the first time it made 11psi and appeared to run absolutely perfect. So, since I had already given the candy to the baby there was no way to get it back if you know what I mean. We discussed it and decided to keep it there and do some more testing on the car to make sure everything was right on. Lag upgraded the fuel injectors to 42lb and also replaced his head gasket with a multi layered steel head gasket that we had custom made for the 928 by Cometic. I had replaced my head gasket a couple years ago with a stock one and when I turned up the boost I pushed it out when I had a fuel problem and resultant detonation. Lag also invested in a Wide Band O2 sensor and programmable meter to monitor the air/fuel ratio through out the operational range of the car. This has provided us with some great feedback and has also confirmed (reason I had a problem stated above) one particular issue that may be problematic with running higher boost levels. I have a remedy for this that is in development and hopefully will get tested before the snow flies here. This BTW is not an issue at 8psi boost. I also purchased a set of EGT sensors and gauges that we will be installing on Lag's car to monitor the fuel distribution and make sure we are getting the correct amount of fuel to each cylinder. Since we have taken the HP levels of the car way beyond what the factory did we need to verify the system will support what we are doing. I would like to think that this is the way the factory would have evaluated it. If we find areas of weakness we will find ways to make it right. Until then, 8psi is what you get with my kit because that is what I feel is well tested and dependable. Besides, 450rwhp is still pretty awesome power if you ask me.

BC

Can you PM or email me about those Cometic gaskets Tim? If there is any lead time involved, I need to make sure they are ready when I bolt everything back together.


Can you go into more detail on the issue you note above?

Thanks!

Tahoe Shark

Excellent job, nice horsepower & torque. How many miles have you driven on this configuration? Are you pushing the car at all? This sounds like the hot ticket! A little to much boost for me but impressive none the less.

Tahoe Shark

Excellent job, nice horsepower & torque. How many miles have you driven on this configuration? Are you pushing the car at all? This sounds like the hot ticket! A little to much boost for me but impressive none the less.

Z

After Lag's, the best run of the day was actually done by a modified 911 turbo of some sort. That one did 298rwhp and also 298rwft/lbs, and was run up to 6,400 RPM. I didn't see the run for that 996 or get the data for it. It was the last car of the day and I was already preparing to leave.

The new exhaust definitely made a difference from the start of the run at 2,000 RPM, and all the way up. A 3" system might be better yet, but there's not a whole lot of room under there for one that size. The chart only really goes down to 2,100 RPM. He's making 300rwft/lbs of torque there now, which is 30rwft/lbs more than he was with the old exhaust system.

There were a few people at the dyno that said the exact same thing.
There are two guys that were there who told me they are now actively looking for 928s, and asked if I knew of any for sale.

I don't know about every day, but I can say that he has every single time that I've ever been in it.

There was also some variation of 911 there with a supercharger kit on it. (Sorry, but I really don't know the difference in "911" model variations.) He made a good bit less than he was expecting to based on the claims of that kit's manufacturer, and nowhere near even 300rwhp. He definitely wasn't happy, and there was definitely a phone call to that kit supplier planned for first thing this morning.