victor25

Yep, if you still have cats and if your still blowing air to the cats, then yes, for the first few minute or so
You can look at post 26 for comparison results

ptuomov

If I understand your post #26 correctly, you are not comparing the intercooled car with and without the smog air pump connected to the intercooler. Instead, you are comparing a car without a heat sink intercooler to a car with a heat sink intercooler.

If you want to do an honest, apples to apples comparison, you will repeat everything exactly the same way but with and without the smog air pump connected. The math is a tyrant in the sense that the full load, full throttle difference will be about 2F between the smog air pump connected vs. not. If you get a double-digit F difference, you either aren't replicating the experiment correctly or you're in line for the next Nobel price in physics.

DKWalser

I like the idea, too. However, I doubt it works even for weekend cruising. Here are my concerns:

Background: To work, any IC has to be cooler than the boosted air passing through it. How well it works is a function of how much cooler the IC is and the size of the IC. How long an IC will remain cooler than the boosted air is a function of the volume and temperature of the cooling fluid passing through it. In this case, the cooling fluid is air from the smog pump. Air is not very effective as a cooling fluid, which is why air-to-air IC's are usually a lot larger than air-to-water IC's for the same engine -- you just need a lot more air than you would water to carry away the heat.

Concern: It's July and you've been cruising for a couple of hours through the Arizona desert. By that time, the IC is apt to be well over 180F. (Ambient temperature of over 100F plus 2 hours of driving equals everything in the engine compartment is too hot to touch!) The smog pump will not flow enough air to make a material difference in the IC's temperature under such conditions. I would expect that, if the IC without the smog pump is 185F, with the smog pump it might be at 182F. Not much of a difference.

185F is less than 240F, so, assuming the boosted air is at 240F before the IC, the IC would provide some benefit. However, to provide a noticeable benefit, the IC would need to be fairly large.

So why do the dyno runs with the smog-pump-cooled IC show a benefit? I suspect that it just takes more time for the IC to heat up. It's a large chunk of aluminum and requires a good deal of energy to heat it up. Which means, if the IC starts out at 80F, it would take a lot of cruising -- with or without the smog pump -- before it heated up to the point of losing effectiveness. If that's the case, the IC would work for weekend cruising if that means relatively short trips. Drive for more than an hour or two, and I suspect the IC will not be doing its job. Using the smog pump to cool the IC is unlikely to extend the time that the IC is effective by a noticeable amount.

Yes, that's just a WAG. I'd love to see some data to know whether my intuition is correct.

victor25

Thank you, Thank you all... Please be seated, I would like to start by thanking the 928 community for there support. I'd also like to thank my wife for divorcing me and allowing me to have the money to play with these cars. Lastly I'd like to thank my High school physics teacher for helping me realize my dreams. Thanks again, and thanks for coming out tonight.. I hope you all have a safe drive home, please keep your Porsches under 100

ptuomov

"They" tell us a lot of things. Like for example, "if you like your plan, you can keep it."

victor25

Dave you are probably correct. Especially in the Arizona Heat!! So for you it'll be an extra $800 for the Bosch 0-392-022-002 water pump, the front mount heat exchange, 14' of 3/4 water hose, relay setup, fill cap assembly, expansion tank, and an extra days or evenings work to get it all installed


OH lets not get started on the insurance thing!!! I no longer have health insurance cuz of that bull ****!! And I am not about to pay $550 a month for insurance that has a $12,000 deductible.




.

Mongo

victor25

As promised I would do a test for before and after with the air pump as a cooling agent.
this is my drive to work 2 days in a row. One without the air pump connected an one with. the difference is not huge but it is there.
This is a first test, and I have not calibrated the air temp sensor, but both are runs are with the exact same settings other than the air pump

ptuomov

That difference appears too large to be explained by the air pump flow. If the power of the car is in the ballpark what we've discussed (1000 kg/h) and if the smog pump pushes out about the typical smog pump number (10 kg/h), it's difficult for the temperature impact to be more than just a couple of degrees F. Certainly not 20 F degrees. Now, either my assumptions about air flow are wrong or the conditions between experiments changed somewhat - the formula itself is correct.

What is clear from the graphs is that the heat-sink effect is large. Intercooler without any coolant flow will work pretty well on the street if one is driving under boost less than 1/3 time.

victor25

This is just the first couple of runs. I agree that it's not the optimum solution, but it does make a difference. Obviously this would never work for racing or hard driving, but it does make a difference and work good for driving around town. It keeps the big boost heat spike under control as an "air pump cooled" heat sink . We all know a good heat exchange and water pump does a much much better job. I will continue to collect data on long and short runs. I will also post a water cooled comparison later.
One thing I am wondering about is if I spend 20 min driving someplace, turn the car off for 10 min, then drive again. This would cause a huge heat soak in the intercooler. The question then is can the air pumps air bring the intercooler back down to a decent temperature?? More info to come.....

ptuomov

If you mean that it works as a heat sink to take out the spikes and cool the boosted periods on average if the engine is 1/3 time under boost and 2/3 under vacuum, then I would agree.

I am highly skeptical of the air pump making more than a couple of degrees difference at steady state high load. Even with perfect heat exchange, the ratio of mass flow rates is such that it can't make a meaningful difference. The only unknown in that conclusion is the smog pump flow rate, which would have to be measured to be 100% certain about the conclusion.

Pfc. Parts

You're using the air pump aren't you.