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supertrapp exhaust and cooling on F4i engine

So what's the right amount of oil after adding all the tubing? Should it be just the standard oil capacity + new tubing volume? :confused
 
plus whatever is in the cooler

Webberstyle said:
So what's the right amount of oil after adding all the tubing? Should it be just the standard oil capacity + new tubing volume? :confused
Click to expand...
 
Right. It turns out, it isnt ALL THAT critical how much oil is in there, as long as you have the minimum amount. We have had serious oil pressure issues since the bike motors arn't designed for lateral acceleration. This year we're doing a dry sump, but in previous years we've used an accusump, which is an extra 3 or 4 quarts of oil that gets plumbed straight into the oil pickup. This way, if we starve the sump of oil, we have a couple seconds before the oil pump runs dry.

However, the accumsump doesn't pull those extra quarts of oil out of the engine until the motor is running, so for a while we run like twice the amount of oil as the engine was designed for. We have no problems with it at all.
 
Since water has a lot more mass than air, it requires a lot more airflow than water flow to move the same mass. We'll be running the stock water pump. I'm going to try a fatass 8A fan and separate it from the radiator as far as possible, and shroud it. I could try finding the water pump specs, measuring mass flow of coolant, finding air mass flow for certain velocities, etc. but in the end I'm not sure if it really matters. Surely, it's complex, but I'm pretty certain if I just use a large-enough radiator with the right fan, we'll have the cooling we need, especially coupled with the air-liquid oil cooler
 
btw..have u messed with the fuel map?? if it runs too lean it will definitely get hotter
 
Thanks Chi. Stuff like that is what judges would frown upon though. This car is marketed as a "weekend autocross vehicle" under $20,000 so they want it kept as simple as possible. You can't even put random aesthetic shit like spoilers on without doing the math for it :rolleyes
 
its called a total loss evaporative cooler system..the sprayer only cost 80 bucks...it uses sprays water on the radiator which in turn evaporates and increases the radiators efficiency...u can do your math on it..it works :) damn the judges...
 
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nah..i never got passed intro to algebra...but being a former marine i have done my fair share of McGyvering:)



Webberstyle said:
Dude, you wanna be on the team? :laughing
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xtasie99 said:
I have to say, you're one hell of a seat of the pants dyno.
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well thank you! the bike in question was my f2 that i'd already put about 12k on before the pressurization of the airbox, so i was very familiar with it. at around speeds way lower, than what you think would matter the bike seemed more "revvy" and the throttle response was better. now i'll admit it wasn't huge, but it was there. wonder what that difference in air pressure does to the engine vaccum and air resistance??
 
Haha, that water tank weighs 30 pounds.

As a comparison, I spent 6 hours making a carbon fiber gas pedal to save 1 pound over an aluminum pedal.

Judges would see that thing as a huge bandaid to fix a problem that shouldn't be there. Pike's Peak cars use them because they are trying to get rid of like 400hp in heat. We are trying to get rid of like 30.

And Miran, to adequately design a cooling system, all those things you said, should be done. The judges will want to hear all of that. However, have fun trying to find the specs on the stock water pump. I'm not sure anyone has got that number, and if they do they arn't sharing. We're running the drysump off of the water pump shaft we're running an electric water pump, which makes life easy for the cooling guy.
 
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xtasie99 said:
P + (rho*V**2)/2 = constant

or:

Ps + q = Pt

where:

Ps = static pressure
q = dynamic pressure
Pt = total pressure

and:

q = (rho*V**2)/2

Assuming a standard day at sea level:
T = 59 degrees Fahrenheit
T = 518.69 degrees Rankine (Rankine = F + 459.67)
Ps = 2116.2 lb/ft**2 (=14.696 psi)
rho = 0.0023769 lb*sec**2/ft**4

At 40mph = 58.67ft/s

Pt = 2116.2 + .5*0.0023769*58.67^2
= 2116.2 + 4.09
= 2120.3 lb/ft^2

= 14.7242 PSI

So, assuming you have a perfect intake that completely stops the air and converts all dynamic pressure into static pressure (which isn't true, since the intake is sucking air) you make an additional .028 PSI of boost.

I have to say, you're one hell of a seat of the pants dyno.
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Nice... but what's the temperature of the air behind the engine and under the gas tank? I seriously doubt its 59 degrees Fahrenheit...
 
I was calculating the difference between two velocites. It doesn't really matter what arbitrary temp I used. But just so you know, that is standard temperature/pressure. Those are the numbers you use by default unless you have a reason to do otherwise.
 
But, it does matter. Look at turbocharged four stroke engines: they typically use an intercooler to keep the air charge temperature down. This is an extreme version of what we're talking about.

Yes, the velocity differences are very small and negliable at less than warp speed. But to say that air temperature does not matter in an IC engine...
 
When the heck did I say temp doesn't matter to an IC engine? I didn't extrapolate horsepower figures- I showed a difference in pressure. You can decide for yourself how many hp 0.028psi of boost makes, or whether that increase needs an intercooler, or if the gravity due to the moon effects the color of your blinker fluid.

I examined the effect of the velocity of the air on static pressure. I compared this pressure with the static pressure at STP. I could have plugged in a temp of 238472395465 degrees on both the static pressure and the dynamic pressure and it would have given me the exact same answer. A change of 0.028psi.
 
FYI it was in the mid 30's the 1st time i took it out with the pressurized box :teeth
 
this is why rain gauges don't have funnels on top of them

xtasie99 said:
P + (rho*V**2)/2 = constant
...
Click to expand...
that looks to me like you have the throttle body out in the wind with no 'funnel' in front of it. at high speeds, the funnel doesn't need to be that big; at low speeds, it would have to be much larger to produce the same "boost".
 
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