I was reading through a book I have, Building 4.6/5.4L Ford Horsepower on the Dyno", and I came across a topic that got me really thinking. The topic is intercooling. Until I read this I thought that intercooling was nothing but good.

I've retyped the article and have attached dyno charts for evidence.

 

Interesting...very interesting

 

Nice but, hope there's no copyright problems....

 

I don't think I have to worry about copyright problem cuz hey, I could just come over and show you the darn book now couldn't I? I'm not selling this info, I'm just sharing it.

 

Under copyright fair use doctrine, it is permitted to excerpt and quote materials for the purpose of review, teaching and training, etc. The law is admittedly a little unclear and non-specific - that allows the judge some leeway.

This sharing is intended to create discussion, so it may well qualify under review. The images, now, well. . .

 

Heck, it made me want to buy the book, so how is that bad?

I always find it interesting when accepted "truths" are put into question and find they shouldn't be accepted so easily. Thanks for the post.

 

The article and pictures have been removed due to copyright infringement. You can summarize the article and using quotes but cannot copy it word for word and post copies of scanned documents. Regardless of whichever debate you want to start about this, feel free to ask the admins if you have an issue as we were told specifically by Brad that this is not allowed. Several sites have been forced to shutdown due to copyright infringement.

 

Ok, now that everything has been removed and we're legal again, what was the thrust of the article. Summarize! You've just piqued my curiosity, so I'd like to hear what you were getting at, I always thought intercooling was nothing but good too.

 

I think it was you lose 3psi of boost when using a intercooler.

 

That's there issue??? Do these folks have any grasp of the ideal gas law? (Pv=nRT in case you are wondering) Pressure by itself doesn't mean diddly squat. Mass flow is what matters. aftercoolers cause pressure lose for two reasons:

1) Resistance of flow through the cooler is greater than section of pipe would be and they tend to have longer piping runs due to the requirement to mount the cooler in the air stream (at least for air to air aftercoolers)

2) Ideal gas law. The volume of the aftercooler doesn't change, but you are decreasing the temperature. The ideal gas law says in a fixed volume, if you decrease the temperature the pressure WILL decrease an equal amount.

The first decrease is an issue and you need to design the system to minimize friction losses. The second reason just isn't an issue. The only thing that matters is the mass and the temperature. Mass should be as high as possible and temperatures as low as possible. Higher mass flow means more fuel can be burned. Lower temps mean a leaner mixture can be burned AND you can use more timing without risking detonation.

For any properly designed and implemented system, the gains from the lower temperatures will more than offset any losses from the slight decrease in mass flow caused by friction.

And yes, I KNOW there are lot more variables to consider when it comes to making power on boost. But for this, we are mainly talking about four: P (pressure), V (volume), T (temperature) and M (mass). All those other variables are really not relevant to the aftercooler issue.

 

It's a total lost cause to explain things rationally like that using physics on this forum. Believe me, I've tried many times. Just call it "magic" and move on.

 

maybe you didn't explain things well enough Jake

 

But isn't the lower temp better for the internals?

 

I would imagine lower pressure would be easier on the internals as well as temperature.

 

It's not a matter of being "easier on the internals" as it is having to retard spark timing and richen up the mixture to prevent detonation with a given fuel octane. In the end, it's pretty simple: Intercooled (or, more properly, aftercooled) air-charge is lower in temp and denser, allowing for more timing advance and a leaner mixture to safely produce more power at the crankshaft, with no change in fuel octane. Period. There is no way that a non-intercooled FI rig can make more power at the crank than an intercooled setup, with all other factors being equal.

 

Well said Dave. This is the truth!!

 

If they didn't get it how I explained it, they're never going to get it. It's the same people that will argue till the end of time about synthetic oil.

 

Not true Jake! Not true! One of my jobs while in college was tutoring other students. Some of them were also engineering students, but most of them needed help with difficult subjects like "Math 100". Aka: high school math for idiots.

Some of these folks just didn't get it. It was worse than talking to a brick wall (at least the brick wall doesn't reply with some idiotic, moronic and just plain STUPID reply!). But, if you keep working at it, keep approaching the problem from many different (and usually VERY creative!) ways, you could actually get a few things across to some of the folks.

But at the end of the day, you REALLY wanted to just bash your own head into a brick wall to dull the pain!

 

Well that's just like your opinion man.

 

Im an engineering student. I understand Math 100-10,000.