pump gas?
- Thread starter juggy61
- Start date
The AVGAS that I have seen is 100LL (low lead). Yes, you can run it, but you will eventually ruin your cat (if it is still installed) and your oxygen sensor.
juggy61 said:
How about elaborate on his question a little.
How much hp on pump gas and what was the turbo used, boost, etc...
Turbo, boost, etc, really don't have that much effect - beyond being able to push that much air into the engine in the first place, anyhow.
Max power on pump gas (or any grade of fuel, for that matter) is controlled by three main factors - how well your head can flow, how cold you can get the intake charge temperature, and what displacement you have in your engine.
Max power on pump gas (or any grade of fuel, for that matter) is controlled by three main factors - how well your head can flow, how cold you can get the intake charge temperature, and what displacement you have in your engine.
the turbo should make a difference. A small turbo running big boost is going to produce a good bit more heat than a big turbo running a lower psi to make the same power
I've always wondered about that. Why is this? Compressing air from atmospheric pressure to 30psi generates the same amount of heat no matter what compression method you are using, whether it's a big turbo or a bicycle pump.gixxer750 said:
Anyone know the answer?
PS: The biggest HP Supra I've seen on pump gas is still 525 at the wheels. And this is a big build, pistons, head, big turbo, huge IC, injectors, standalone, etc, etc...
CPT is correct. Typical avgas is l00LL. Because of the lead in it you'll trash your emissions gear. Not to mention the stuff is expensive these days. I buy 90 gallons at a pop and paid $4.50/gallon just a few days ago.
(LPG)
You know when via two methods.
Either you get some kind of device that can monitor our timing, in which case you should be able to see when the ECU starts to pull timing to combat knock, or you go to a dyno with an external knock sensor that can detect the pinging directly.
If you start to experience knock, you need less boost, better fuel, or a richer air:fuel ratio, or possibly a combination of these.
Edit: And IJ is right on the money with the octane boosters, they are a simple way to painlessly separate you from your hard earned coin.
Either you get some kind of device that can monitor our timing, in which case you should be able to see when the ECU starts to pull timing to combat knock, or you go to a dyno with an external knock sensor that can detect the pinging directly.
If you start to experience knock, you need less boost, better fuel, or a richer air:fuel ratio, or possibly a combination of these.
Edit: And IJ is right on the money with the octane boosters, they are a simple way to painlessly separate you from your hard earned coin.
GrimJack said:
Imagine a straw as your small turbo and pipe as your big turbo. Now pump 30 psi through both of them. The straw will flow 30 psi, but the air would have to move at a much faster rate causing more heat. The big pipe will flow the 30 psi at a slower speed, creating less heat.
So the turbo size does matter.
I have a few dyno graphs of a few turbos.
MK3 GT40 .88AR 20psi 562hp.jpg
MK3 SP61Bolton 24psi 543whp.jpg
MK3 SP63 22psi 478whp.JPG
MK3 SP63 24psi 532whp.JPG
MK3 SP74 31psi 564whp.jpg
Granted there are other factors that affects the overall power, but you can see that the bigger turbo makes more power with less boost. Except the SP74, don't know what happened there... :dunno:
Hmm... I see the analogy... but I'm not completely understanding the logic.
If the turbo was the biggest restriction in the flow, I could see that.
I realize that larger turbos will make the same or higher power levels at lower pressures, but I've always been under the impression that the flow of air at, say, 500 whp is virtually the same no matter what turbo is pushing it.
So... why would a turbos of different sizes create different heat levels at the same airflow?
If the turbo was the biggest restriction in the flow, I could see that.
I realize that larger turbos will make the same or higher power levels at lower pressures, but I've always been under the impression that the flow of air at, say, 500 whp is virtually the same no matter what turbo is pushing it.
So... why would a turbos of different sizes create different heat levels at the same airflow?
GrimJack said:
compression...as you compress air energy is converted into heat. The less you compress it, the less heat is generated. You can flow 200CFM @ 20psi or you can flow 400CFM @ 15psi, while 400 is greater than 200 the amount you compressed the air is less and thus less heat was generated.
or at least that's how I was shown
GrimJack said:
It has to do with the efficiency of the compressor wheel. The turbo is like an air pump. We'll make the analogy that we have one pump that is twice as big as another. Theoretically speaking you can move twice the air with the larger pump rotating at the same rate (that is not actually correct, but for this example we just need to know that the bigger one pushes more). Now when a small compressor is moving a large amount of air, it is whipping through the air at a very high speed creating heat. The larger turbo can move the same amount of air at a slower speed, disturbing the air less and causing less friction giving a cooler charge.
When we talk about boost we are actually representing the volume flow rate of air. In this case the engines intake is the largest restriction and that is why manifold pressure occurs. However, it is mass flow rate that makes the power. In this way, a larger turbo can provide a cooler more dense charge into the intake that results in less boost, but more mass flow and you get more power. Hope this makes sense.
yep, called the adiabatic process
http://www.stealth316.com/2-adiabat1.htm
grim, youre right, 30psi from a smaller turbo produces similar heat as 30psi from a larger turbo, however since the smaller turbo takes more psi to make the same power, at the same power levels, the larger turbo will run cooler.
in other words, if 30psi from the smaller turbo makes 525hp on pump borderline detonation, it will take less pressure, therefoe less heat to make the same power from the larger one so you still have a little more to play before reaching borderline det again.
http://www.stealth316.com/2-adiabat1.htm
grim, youre right, 30psi from a smaller turbo produces similar heat as 30psi from a larger turbo, however since the smaller turbo takes more psi to make the same power, at the same power levels, the larger turbo will run cooler.
in other words, if 30psi from the smaller turbo makes 525hp on pump borderline detonation, it will take less pressure, therefoe less heat to make the same power from the larger one so you still have a little more to play before reaching borderline det again.