jorj7

Intercooler temps need to be below 199 degrees (non pressurized system at 6,500 ft elevation), though I get concerned when it's over 190 and I try to keep the coolant temps below the red line on the temp gauge. Above that I'll get knocks and loose power (ignition retard).

__________________
George
90 S4 Grand Prix White (Murf #5 - 210 mph top speed)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com

Rob Edwards

George, are you logging the actual race on the ST2, or just when you're testing with Bill in the car? It'd be awesome to see the datalogging of the 90 miles. _Lots_ of big dots down in the lower right corner of the graph...

jorj7

In May of 2011 Bill and I were going to ST2 log the race, but the race was red flagged. I hadn't wanted to try doing the logging while I'm solo just in case something goes wrong with ST2, EZK, or LH. I have logged some races with the LM-1/LMA-3.

__________________
George
90 S4 Grand Prix White (Murf #5 - 210 mph top speed)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com

GregBBRD

What fuel/octane do you run?

ptuomov

You have the option of increasing air flow further and also to increase the heat exchanger sizes, since it’s a race car. Are you thinking that you’ll lose more in terms of additional drag than what you’d get in terms of cooling benefits? There’s a lot of air flow one can work with at 218 mph...it’s like airplane up there at those altitudes and air speeds.

Please remind me if you have only external evaporative cooling with water spray, or are you also spraying water into the intake manifold? How large is your water tank?

IcemanG17

I'm wondering if a new intake would help? Maybe the one Doc makes that gave such great gains on lightly modified 5.0 and especially the strokers? Of course more power = more heat which seems to be the limiting factor?

Erik N

BADASS!

ptuomov

In my opinion, the stock S4 intake is reasonably well matched with a centrifugal supercharger, stock S4 cams, and 6200 rpm max. If you look at the pressure and mass flow curve of a belt-driven centrifugal blower, you need to augment the torque curve at mid range and then you can let the naturally-aspirated torque curve to fall down as rpms go up.

hacker-pschorr

You both make good points, but where do you draw the line??

Sure he could throw out the stock intake, make different cams, maybe a stroker crank, maybe a Corvette transmission, completely re-do the body for better aero, new ECU etc... where does it end??

The answer is, it will never end unless you finally put your foot down and just work with what you've got, and sometimes that is the best way to go.

I think what makes this project so damn impressive is just how stock it is, and he still has more room at the table to go faster without really changing anything!! No I'm not saying George's car is stock....hopefully I'm making some sense here

I'm not picking on you guys, this is a challenging problem I deal with all the time with my projects and ptuomov I know you do too. What I like most about your car is same as George's car, how much of the stock parts you retained.

Like Twin Turbo Todd likes to say: "Making power is easy, everything else is difficult". He knows his car in it's current form with those turbo's is good for another 400-500hp, but that will open up a lot of other issues with cooling, drive-train longevity, and most important: traction.

ptuomov

I like the philosophy of making minimum necessary changes from stock and also not making changes that make things worse. A part of that philosophy is identifying the bottlenecks. In Mr. Suennen’s case, he’s identified cooling. I think it’s a logical thing to ask how can that bottleneck be alleviated with minimum changes.

As I posted earlier, bigger cams and a custom shorter runner intake manifold alone would not be beneficial changes to this engine, unless a lot of other things would be changed also. Making those changes while keeping everything else wouldn’t be something that I’d want to do.

Jim Morton built a helluva engine for this car, too.

SwayBar

George, congrats on your run - excellent prep AND driving!

The one thing that concerns me though is the intercooler temp, that is much too warm.

Let's say the ambient temp is 100 degrees. The air temp out of the intercooler and into the engine should be roughly 135 - 140 degrees.

It appears that your reported intercooler temperature is the water/coolant itself, which means the actual air temp entering the engine is even higher than that.

More efficiently removing the heat from the intercooler-coolant will allow lower air temps entering the engine which first and foremost promotes reliability by reducing the chance of detonation.

I know that will be tough given lack of room, but maybe you can consider increasing coolant flow with a bigger pump and lines, and/or increase the amount of coolant, and/or increase the size of the heat exchanger, and/or more efficient air flow thru the heat exchanger - all in an attempt to bring those intake charge temps down to a more reasonable level to maximize your reliability and chance of finishing.

jorj7

Greg,

I use the highest octane unleaded race fuel I can find at the location. In Ely that's 104 octane. I'm also running water injection, which raises the effective octane rating. Back when they allowed water/methanol injection I was running premium pump gas, but they banned that in 2014.

__________________
George
90 S4 Grand Prix White (Murf #5 - 210 mph top speed)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com (http://928.jorj7.com/)

ptuomov

I agree that the intercooler cooling circuit is the first thing to look at if one is looking to make improvements.

The good news is that the charge to coolant heat exchanger is clearly working. So the improvements can be found from bigger water reservoir, faster water circulation reservoir, larger heat exchanger shedding the heat from the coolant, and more air flow thru that heat exchanger.

jorj7

As I've gone up in speed classes, I have increased the size and number of intercooler heat exchangers. I currently have three, a larger one in the passenger fender and two smaller ones in the driver's side fender. I am running water injection as well as the water evaporative sprayers. I have one pre-supercharger and one pre-throttle plate nozzle. These were used when I was running water/methanol injection, but the nozzle sizes were changed when I went to only water. This is an Alcohol Injection Systems kit with a AEM progressive controller. I have a 5 gallon fuel cell that I use for water.

__________________
George
90 S4 Grand Prix White (Murf #5 - 210 mph top speed)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com (http://928.jorj7.com/)

jorj7

I'm sure upgraded intake, cams, valves, heads, and exhaust system will help get more power but I've got limited budget and expertise. As noted, heat is a big limiting factor. So lately I've been focusing on that and aerodynamics. Also any other mechanical thing that breaks or needs attention.

__________________
George
90 S4 Grand Prix White (Murf #5 - 210 mph top speed)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com (http://928.jorj7.com/)