"Cold Air vs. Short Ram"

[5.0Thunder]

The CAI thread earlier got me thinking about a question I have always had but neglected to ask.

Has anybody run any dyno tests using Short Ram (hotter air, less resistance) vs. Cold Air (cooler air, more resistance)?

I would assume that the increased flow resistance of the extra tubing in a cold air intake would decrease flow compared to a short ram, but does the warmer air in a short ram kill a similar amount of power? Is the power decrease due to tube length in a Cold air negligible compared to the decrease caused by warm air in a short ram?

[Damnittsteve]

Of god. Is this not discussed enough all over the net?

[CWO]

Of god. Is this not discussed enough all over the net?

No, every topic ever posted here has never been discussed anywhere before. Google links directly to this site. STFU if you have nothing to say.

OP, I wish I had more to add, but I couldn't tell you the benefit of one over the other. My thinking is that any gains would be negligible.

[whitetrash]

If memory serves me correctly the short ram set up netted the same or better power on the 03 cobra. And less chance of sucking up water

[46Tbird]

A longer intake tract means there is a higher volume, and therefore mass, of air that is moving. That air has inertia, which helps to load the cylinder when the intake valve opens.

There is a point where the effect is most pronounced, and you can tune for that.

In general, thinner and longer runners create more power at low RPMs, but become restrictive at high RPMs. And in general, short fat runners make power at high RPMs but don't carry enough air mass to fill cylinders at low RPMs.

There is a perfect visual represention of runner length out there: early 60s dual-quad Mopars.

The big Chryslers needed a lot of torque to get rolling so they used long, narrow intake runners:


The Max Wedge cars were set up for high RPM, so they used short, large runners:




Same basic logic follows with intake tubes. Sure, you can slap an air filter on your throttle body (if you're speed density) and give it a go. My guess is you'll be slower.

[samuel642000]

Of god. Is this not discussed enough all over the net?

Can you go back to dormant ?

[91CoupeMike]

Anderson power pipe.

Next

[00pooterSS]

The CAI thread earlier got me thinking about a question I have always had but neglected to ask.

Has anybody run any dyno tests using Short Ram (hotter air, less resistance) vs. Cold Air (cooler air, more resistance)?

I would assume that the increased flow resistance of the extra tubing in a cold air intake would decrease flow compared to a short ram, but does the warmer air in a short ram kill a similar amount of power? Is the power decrease due to tube length in a Cold air negligible compared to the decrease caused by warm air in a short ram?

Longer piping doesn't create a restriction. It actually causes the air to build velocity and help with V.E.

It also has the added benefit of cooler air.

In short.. go long.

[Damnittsteve]

Can you go back to dormant ?

depends, can you make it worthwhile to me?

[Lone Star Performance]

The issue with back to back dyno testing is that they are always done with the hood up and fans blowing at the car, so the heat is always pushed up and away from the motor, so either one on a dyno don't prove to be much more than the other, the fender well kit being marginally better. BUT, real world situations, the filter in the engine bay gets HOT ass air being pulled in, whereas the CAI air is always ambient temp.

I had good results switching from my JLT ram air to the Kenne Bell Cool Air kit on my car. Air charge temps were consistently lower with the filter in the fender. Granted this is on a blower car which generates a lot of heat under the hood

Here is a good read regarding the two....

http://www.kennebell.net/KBWebsite/Common/pdfs/HotAirWARNING.pdf

[5.0Thunder]

A longer intake tract means there is a higher volume, and therefore mass, of air that is moving. That air has inertia, which helps to load the cylinder when the intake valve opens.

There is a point where the effect is most pronounced, and you can tune for that.

In general, thinner and longer runners create more power at low RPMs, but become restrictive at high RPMs. And in general, short fat runners make power at high RPMs but don't carry enough air mass to fill cylinders at low RPMs.

There is a perfect visual represention of runner length out there: early 60s dual-quad Mopars.

The big Chryslers needed a lot of torque to get rolling so they used long, narrow intake runners:


The Max Wedge cars were set up for high RPM, so they used short, large runners:




Same basic logic follows with intake tubes. Sure, you can slap an air filter on your throttle body (if you're speed density) and give it a go. My guess is you'll be slower.

Great explanation. It makes perfect sense as far as moving air mass and inertia. I never thought about the stream of flow coming into the filter of a short ram setup and the boundary of that stream. Intuitively, it would seem that there would be less vacuum in a short ram setup but there would definitely be much less moving mass in the control volume of the intake.

Longer piping doesn't create a restriction. It actually causes the air to build velocity and help with V.E.

It also has the added benefit of cooler air.

In short.. go long.

Longer pipe does always create a small (mostly negligible in our slow flowing engines) increase in flow resistance due to friction at the walls (also why they are always smooth) and bends throughout the pipe system. You're definitely right about velocity increasing in a pipe as opposed to open atmosphere, due to mass conservation principles where Flow Rate = Cross Sectional Area * Velocity. Decreasing the cross section (using a tube as opposed to open atmosphere) proportionally increases velocity per unit flow rate. Of course a very small cross section will decrease flow rate so velocity can't linearly increase but nobody is trying to downsize their flow tubes really.

[racrguy]

Another thing to think about is the surface texture or the lack thereof. Sometimes a "rough" surface will make more power than a smooth one because of boundary level air.

[5.0Thunder]

Another thing to think about is the surface texture or the lack thereof. Sometimes a "rough" surface will make more power than a smooth one because of boundary level air.

Don't quite understand this concept. Texture only causes turbulence and the only benefit of that would be the mixture of fuel and air, but the flow pattern changes entirely once the air enters the manifold runners before injection anyway. I believe you would want a laminar flow before fuel injection to increase velocity/inertia, then the valves could cause enough turbulence to mix/atomize the air/fuel before compression and combustion

[00pooterSS]

Longer pipe does always create a small (mostly negligible in our slow flowing engines) increase in flow resistance due to friction at the walls (also why they are always smooth) and bends throughout the pipe system. You're definitely right about velocity increasing in a pipe as opposed to open atmosphere, due to mass conservation principles where Flow Rate = Cross Sectional Area * Velocity. Decreasing the cross section (using a tube as opposed to open atmosphere) proportionally increases velocity per unit flow rate. Of course a very small cross section will decrease flow rate so velocity can't linearly increase but nobody is trying to downsize their flow tubes really.

And I thought I was being technical lol.

Cool to know though.

Back to your original question, I have nothing to back it up, but I would have to say the benefits of cooler (denser) air have to by far over come the loss due to the very minor restriction of the longer pipe. The pipe is hardly that much longer anyway on most vehicles.

[5.0Thunder]

And I thought I was being technical lol.

Cool to know though.

Back to your original question, I have nothing to back it up, but I would have to say the benefits of cooler (denser) air have to by far over come the loss due to the very minor restriction of the longer pipe. The pipe is hardly that much longer anyway on most vehicles.

Yeah, I agree with you about cooler air being more advantageous and outweighing the disadvantage of increased plumbing. I wish I had some data recording equipment to see exactly what temperature difference there is in a fender mount as opposed to short ram.