Warren928

So what your saying is that the MAF, fuel pump, and raidator cannot withstand short runs of 600 hp spurts? I am not a consistent track racer who pushes the envelope continually, and I wont be doing several 1/4 mile runs on after the next, my style of driving is fairly laid back with the exception of wanting massive amounts of acceleration occasionally. I think most blown 928 owners are in the same catagory.

Are the Tim murphy SC's running 515 rwhp using a modified MAF, upgraded pump, raidiator and other parts not mentioned in their typical kit?

Z

On both Tim and Lag's car's the MAF is stock. Lag's 513rwhp and Tim's 525rwhp were with the stock fuel pumps, as well as the stock radiators. The parts that differed from the basic kit were the pulley's used to make higher boost. Tim's car currently has a different fuel pump and fuel delivery configuration. That was done after the 525rwhp that he had, but before his most recent 556rwhp results. Lag changed to 42lb injectors some time after his 513rwhp, while Tim has 30lb injectors. You will not peg the MAF at 600 crank horsepower. It does not max out at 5v like has been claimed at times.

Warren928

Z, did they have any run hot problems or run lean conditions at those levels? Does the 86 fuel pump differ in volume capacity from the 87 and up?
Anybody know how much HP the stock MAF can handle?

CMW

After 7 pages of "mostly" reading all the posts my 1 question is to Warren is what is the goal behind the goal. for example is the goal to just reach 600 Crank HP or for what.

On my Supermodel car my goal was to get sub 5 sec 0-60 times and 12's quarter miles.
It needs to be my daily driver and maintain the same general level or maintenace and relibility
as a stock GTS.

Warren928

Chris, I want to reach the 600 hp mark for a number of reasons. First, its fairly unchartered territory on an 86 shark which makes the goal a great accomplishment in my own opinion. Secondly the benefits might be great. There is more potential for 1/4 time's in the 11's, 0-60 times in the low 4's or even high 3's, not sure on the 0-60 potential.

blau928

I vould likink to vish eferyvon a good luck and happy drifink viss der 928 Kompressor....! May vee all haf 600 PS and drife verry slowly..

Otto und Herr Wachtmeister Klaus from Comedy in the Auto Club. Brought to you by Dyno Charts Worldwide, "Giving you the highest power peak on your chart, Area under the curve is no longer relevant when you have the tallest peak."

Otto: Ja, herr wachtmeister, mein auto ist 600PS stark, aber ich fahre nur 100kM die stunde warum das ist nur fur spiel..

Klaus: Gibst schon in Amerika "bragging rights" dabei von "dyno chart".. Der auto ist naturlich unikat, und gut zu haben.... wunderbar...! Man, du musst nicht ein Porsche haben, ein amerikanischer auto fur das ist zehr super... Bei uns in Deutschland wir wollen fahren auf der autobahn, und nicht spinnen uber das "dyno chart..." Wenn der auto ist so stark, mann must auf der 'ring fur ein tag... kein 30 sekunden auf dyno.... oder..?

Otto: Aber das ist Amerika, die loite kann das nicht... Nur auf "Open road racing, oder bei renncourse... Ferstehen zie..?

Klaus: Nein, aber wiefiel mal auf ORR oder Rennen..?

Otto: Einmal die jahre.. Und ich fahre stoplight GP auch.. Wissen sie..? Sowie Road & Track von 0-100km/h auf 5 sekunden, und macht spass..!

Klaus: Liebe Otto, mein gute freund auf 20 jahre lang... Nochmal... Du hast ein Porsche, und das ist kein drag racer... Wenn du will das haben, warum kaufen sie nicht ein davon..? Das ist sowie ein drag racer auf die renncourse Hockenheim oder so... Unglaublich...

Otto: Ja, du hast schon rechts, aber, in Amerika ein mann ist sehr individual, und kann was er will mit alles...

Klaus: Alles Klar...!

Ladies and gentlemen, this excerpt of Otto and Klaus has been brought to you by Comedy Hour on the R'List...

Have a nice day...! Nicole, you will get lots of email for translation...!

Z

No
Have no idea if there's any difference in the '86 and the '87+ pumps.
The one on Lag's car had not maxed out yet at 513rwhp.

blau928

Warren,

Two identical cars:

Car A with less ultimate peak power, but with more total area under the power curve.

Car B with more peak power and less area under the power curve.

Car A will accelerate faster through the gears than car B provided the level of traction is not overcome... This is undisputable physics... If it is acceleration you want, and you are chasing the stoplight GP, then you need the power lower down, so that you can launch better "out of the hole".... Ask any of the experienced racers, and they will concur... There was just a lengthy discussion on this principle by Mark Kibort in another thread referencing final drive ratios and average torque/HP applied to the wheels over a period of time... Go look it up, it has many excellent points.

In any event, you will have to manage traction at this power level. Furthermore, stoplight GP is an entirely different game than going for more "total power" or area under the curve. If you just want a peak of 600 CHP, then that is much easier than a fatter curve or more total HP..

I will not get into the debate about TS VS CS, as this is a futile proposition on this forum. Either can be tuned to produce tremendous powerbands.

Ken,

Design your system for your intended use, and you will be very happy. Lots of points already posted, and sufficient to design and build anything you want.

Mike,

According to John Speake, and several others, the MAF can be pegged and more rapidly degraded using a blow through design as with the CS systems. John has emulated the MAF, and redid Tim's MAF as well as far as I know. A pull through as with the TS systems does not have this limitation (pegging the MAF) unless it is at higher levels, due to the MAF being on the intake side. Todd from Protomotive has also peged the 928 MAF's when I spoke to him years (2) ago. The amount of airflow is also related to the BSFC of the engine, as the power output is a direct derivative... (fuel+air+spark timing)

In any event, I prefer to design for reliability over the longer term. The MAF may not be pegged the first 20 times, but when it does, you will have to buy a new one.. In addition, Warren has an 85-86, and I think he can only get a "kit" from Andy K at this point. The info from Tim's kits would not equally apply due to differences in the design and airflow of the different systems.

Marc,

I agree that a properly built Blown Stroker (6.0L or 6.5L) would make more power across the powerband than a blown 5.0L or 5.4L. I have said this since the first time we spoke about me wanting to build a Forced Induction Stroker.

Congrats to those that have done so (Pressurized their cars), and Best of luck to those that are trying. And yes, may we all have more powerful 928's and enjoy the sarcasm.

Cheers,

Warren928

Oh sure, that's exactly my point too!

Z

Well, I can definitely say that the MAF was absolutely not pegged on Lag's car at 513rwhp. That's because I was personally sitting in the car measuring it for myself. I will also say that it would not be pegged by any 928 engine that I've ever heard of. Obviously there will be some airflow level that would eventually peg the MAF, but it would very likely be an amount of air that what would make significantly over 1,000hp. If a 928 engine somewhere is ever built that has a high enough power level to peg the MAF, it will definitely not be using the Porsche engine management system anymore anyway. The only instance where the MAF would be more rapidly degraded with a blow through system would be if no intercooler was used at higher boost levels, or if the intercooler were inadequate.

John redid a MAF for Lag, but the car was never really run with that MAF on there other than for some brief testing. Tim's MAF is a stock one.

The MAF output is a direct result of the mass of air passing through it. It doesn't make any difference whether that mass of air is blowing through or being drawn through as far as pegging the MAF would be concerned. What moves the air through is the pressure differential from one side to the other, and the MAF just measures it. If it were to occur, the MAF would get pegged at the same level of air mass passing through it regardless of whether the air was being blown through or drawn through.

If that's true, I'd be very interested in hearing any details of the engine, since it would have had to be making way, way above the power of any 928 engine that's ever been mentioned anywhere that I've heard of. Do you know what output voltage level it was supposed to have been pegged at?

Trust me, long before you peg the MAF even once, you'll be much more concerned with the reliability of an awful lot of other things, and you'll wish that a new MAF was all that you had to worry about.

Warren928

Blau, I think murph's kit will work on my 86' 928 with the intake manifold / fuel rail conversion to S4, but I could be wrong. I'm not sure if anyone has done a murph kit on an S3.

blau928

Mike,

Maybe there is a misunderstanding on what pegging the MAF actually means.... The LH as far as I know, does not support more than 5 volts as an input to correlate with the load tables on the chip. In other words, there are no load tables for values greater than the 5v. While the MAF itself may not be destroyed from the airflow, the pressure and heat of the aircharge will destroy it faster in a push through versus pull through due to the fact that on a pull through system the charge is NOT pressurized... The heat from pressurizing is the culprit of destruction, and the cyclical use at elevated temperatures will destroy it faster than ambient air moving through it with no positive pressure.... Very simple physics here, no need to guess.

Th LH will set an error code aka "limp home mode" if the detection of an erroneous sensor reading is intercepted..... If you are at such high power levels, and this happens, the car will run very lean. Tim's kits do not as far as I know come with a secondary fueling system that would overcome this design limitation of using the stock LH and MAF. Warren has not spoken about replacing the electronics with another "box" such as MOTEC, or an Electromotive Tec3 etc. In addition, I don't think anyone's kits comes with this as part of it.

In terms of reliability, there are many things I am saying to uprgrade before getting to 600hp, while many including yourself are saying are not neccessary. In my philisophy as I have stated earlier, the approach should be systematic, and not piecemeal. This is a fundamental difference that I have had with many, and agreement with some. Warren has asked for "bolt on" to put on a stock 85-86 928 32V, and I have said repeatedly to him to consider ALL the variables.....

With respect to Tim's kit, I have said I think it is extremely good. However, there are in my opinion differences which I would upgrade certain parts, or replace them entirely. Now, as I was strongly eluding to in my sarcastic remarks in German, for most of the people on this list, and in this country, they will not be using their cars to the limits it would be in Germany. Unless they race on the track, or drive in the open road racing events. Even then, it would be a few times per year, and not on a daily or weekly basis. If they did, they would be in jail for a very long time irrespective of how good an attorney they had.

Warren,

I think it is now time for me to say enough.... No hard feelings, but as many before me, and I am sure many after, I will be refraining from commenting on what why and how one should approach engine design and building. It is becoming a he said she said, I know, therefore you don't, or my friend did this, so it must be right. As before, I wish everyone well in their pursuit of power in the 928 community.

Cheers,

Fastest928

the maf (closed loop) stops at approx 60% throttle. Not even strokers with high VE and almost 500 ft lbs of rwTQ peak the maf at 60 % throttle! It is irrelavent what the MAF reading is past 60% throttle.

Once at full throttle, or past the 60% throttle point, the ECU uses a fixed map...whose offset is determind by the relationship between the maf and o2 readings...most if the "full throttle map offsetting" is done in the first 10 minutes of startup.

Engines do not know is the air supply is "boosted" or not....the 928 only understands Mass air flow, and to a lessor degree, throttle position, engine temp, etc.

Marc

Mongo

hmm I just thought of something..

Didn't Kelly Moss Motorsports make a 928 32v motor that was 800 HP and carbuerated too??? I read about it a while back that it was supposed to be dropped into a tubular frame chassis-ed 944

Jim bailey - 928 International

Stig it has individual throttle bodies so it looked like it had carbs but is injected.