jackhild59

iTrader: (7)

I hope you misunder-estimated me. The only thing we care about is moving more air through the system. Temperature reductions are the result of moving more air. To do this, the OP must reduce pressure under the hood, thereby increasing the pressure differential measured across the heat exchanger.

Your packing ice around an intake example is not in the least related to my point. I believe that it tells me you don't understand my point, so I am going to ignore that. BTW, I checked the thread and you seem to be the only poster talking bout turbochargers- and yes Greenbuds car is turbocharged, I know that.

Let me restate some things. The OP intent/hope is to reduce temps under the hood. The poster is speculating that a Vented hood will help him accomplish that.

To accomplish this he must move more air. The only way he has to measure airflow is to measure pressure differential. He needs to reduce the pressure under the hood.

How is this so complicated that only *you* understand?

ATRON3000

What are the advantages, if any, of a v-mount intercooler... it would seem that hot air from the radiator would warm up the intercooler more.

In what way is it more efficient than a front mount?

FC-Dan

I could be wrong, but I believe that its overall airflow that matters more, not the pressure. Just because you increase the pressure on one side of the intercooler does not necessarily increase airflow.

FC-Dan

It looks like that he just misunderstood what you said. It appears that he thought you were talking about boost pressure when you were talking about the pressure difference between the front and the rear of the intercooler. But I believe that Evil Aviator has a point with the intake temps. I imagine that greenbuds whole purpose of this v-mount/vented hood setup is to reduce intake temps. Lower engine bay temps are also a good thing but I would say the focus is to lower the intake temps. Not to mention that it looks badass.

And to answer your question atron3000, v-mounts allow fresh air to pass through both the radiator and the intercooler. Front mounts restrict air to the rad. And v-mount systems have less piping, which I know is a good thing, but I honestly cant tell you the reason why at the moment. Less lag i suppose?

And your v-mount setup looks awesome njgreenbuds.

jackhild59

iTrader: (7)

The pressure differential is a function of airflow. As the EA stated, the actual airflow is difficult to measure. For our purposes we cannot measure or calculate the airflow because we do not have enough information. Measuring the pressure differential is for all practical purposes measuring the airflow.

Make delta P higher, you have more airflow. Make delta P lower, you have less airflow.

That is why you measure the *differential*.

jackhild59

iTrader: (7)

But it is not obviously relevant to the discussion. I cannot even tell from the posted pics if greenbuds intake is under hood or ambient, since the pics are of hoods, vents and vmounts.

You can imagine that, but that is not what he said or implied. Since njgreenbuds said to 'reduce temps', I took it at face value. Since the primary purpose of a V-mount is to improve ambient airflow to the rad for improved cooling vs. a FMIC in front of the rad, and in his second post he asks for a discussion of the physics affecting airflow, this is the direction I went.

Increasing airflow will reduce temps-on everything-radiator, intercooler, intake piping, etc etc.

Yes, it does

stylEmon

iTrader: (2)

I would think that logging and comparing intake temps and water temps in all three tests, from the same baseline, would be sufficient...?

Evil Aviator

No, it will not. If you post your results it will just add to the misinformation on the internet.

Yes, I did think you were initially talking about air pressure within the system.

Your idea of measuring pressure under the hood would probably work OK if the system were fully ducted. However, it would only indicate which setup flows better through the intercooler core rather than how much it affects performance. Please keep in mind that the flow bench testing you see in auto magazines is considered the lowest form of life in the realm of performance testing, and it is usually only used when it is impractical to properly test the system as a whole, or when a vendor wishes to inflate the performance value of their product. Most professionals measure airflow through a heat exchanger with an anemometer as opposed to a manometer.

Also, testing the intercooler inlet and outlet pressure would not do such a great job of indicating any natural convection that would be expected of a vented horizontally-mounted intercooler.

I was under the impression that the OP was in search of better engine performance. Are you saying that he was actually concerned with the temperature of his hood?

Anybody with 1-2 years of college studies in the subject matter should understand the basics. Unfortunately, most people reading this do not have such a background. It is not possible for me to teach to that level in a few internet posts, and there is very little chance for somebody of average intelligence to understand an incredibly complicated book such as Aerodynamics for Naval Aviators without an instructor. If you have read a lot of my other internet posts, you will know that I always try to explain physics as much as possible so that the members of this forum can figure things out on their own. However, I am simply not up to the task in this case. If you have perceived the stated limitation of my abilities as arrogance, then I guess I am doing pretty well overall even though I do not have the competence to accomplish everything that I would like.

You are correct. However, if you use the same intercooler and test the car at the same speed, then that would remove a lot of the variables such that pressure testing would probably work OK for simply testing to see which setup flows better.

Yes, less piping volume would decrease lag, although only by a small fraction of a second. Still, less lag is less lag, even if you can barely feel the difference.

In my viewpoint, the biggest performance advantage of a H-mount intercooler is the elimination of the two 90 degree pipe bends that are typical of an FMIC system.

The problem is getting the same baseline. Heat exchanger efficiency is generally defined by the change in temperature (T2/T1) at a given ambient temperature (T0) and airflow rate through the core. Common testing procedures ignore the airflow rate factor by maintaining the same vehicle speed in each test, resulting in the empirical formula of E = ((T1-T2)/(T1-T0)). You would need to have the same ambient temperature (T0) and compressor outlet temperature (T1) if you intend to yield valid results by only recording the IAT (T2). While you could maybe luck out and have similar atmospheric conditions (T0) for each test, you can forget about having consistent compressor outlet temperatures (T1). Therefore, you would at least need to measure both T1 and T2, and at least spot check T0 to make sure it is similar in both tests.

As for measuring both the radiator and intercooler, I guess it is just my personal opinion that the radiator doesn't really matter. That is simply based on my viewpoint that a cooling system either works or doesn't work. Whether the radiator works better or worse, there will be no significant performance gain or loss as long as the radiator can at least keep the engine at its intended operating temperature. Therefore, if the radiator works in the first place, making it "better" will accomplish nothing of value. The intercooler, on the other hand, WILL affect engine performance if it works better or worse.

NJGreenBudd

iTrader: (1)

Look, simply stated: Evil Aviator knows his ****. Point blank, don't F with Evil.

I took physics, I understand temperature exchangers, my bottom line is whether or not a vented hood will make a big difference in intake temps. I am not going to try to log pre and post VMIC pressure, I am really only interested in intake temps under boost, with different hoods.

My setup is not nearly finished, I have a lot of ducting to be done, I have things to clamp and to to seal, I'll post once it's finished.






On a separate note, I was going to have to wait 12 weeks to get my hood delivered but should have it in two weeks due to pure luck, can anyone guess my final hood design?

FC-Dan

Hmm, did you get the trusty dremel out and cut a bunch of strips out of an NA hood, then take a pair of pliers and bend up the rear parts of the remaining strips? Voila, free vents.

stylEmon

iTrader: (2)

panSpeed?

NJGreenBudd

iTrader: (1)

I was going to make my own hood but opted to buy one, by the time you add up the cost of an NA hood and some vents you might as well pay a bit more for one that is already proven and looks nice,

It's not a not Panspeed either.

Hood should be in the US by the 8th, and here a few days later.

Unseen24-7

I came across this a while back and it really got me thinking...

http://www.240sx.org/links/installs/hood/hood.htm

Obviously for a vmic setup (or na for that matter), the vent would need to be much bigger than the one in that write-up. If you are really concerned about the loss of strength in the hood I guess you reinforce it with some fiberglass (or CF).

IMHO, that is the cheapest/easiest way to get a stellar vented hood.

stylEmon

iTrader: (2)

Shine Auto is gonna make the PanSpeed hood if they get 15 people.
They want 400!!!! I am in, who else?

https://www.rx7club.com/shineautoproject-161/fc3s-panspeed-style-drop-vented-hood-842889/

NJGreenBudd

iTrader: (1)

stylEmon

iTrader: (2)

looks nice. Have you seen any temp drops?

NJGreenBudd

iTrader: (1)

Haven't driven it with the new hood yet, just got it delivered yesterday and fit last night. I'll post up once I have some intake temps with the new setup. Though, I'm having trouble finding my logs of the TMIC setup, maybe someone with a similar setup(TO4B vtrim, TMIC, stock hood) could post temps so we can compare?

88rxn/a

iTrader: (6)

wow, dude that looks really good!

connors14

iTrader: (2)

just an idea could u make a front lip to direct air upward to increase flow through out the vmic and out the top of the hood?

levelzero

iTrader: (1)

I actually did my hood a few weeks ago. I'm still NA and did it mostly to help reduce heat soak when stopped. Stopped at a light you can actually see the heat waves coming out of the passenger side vent. The pics were taken before I had finished sticking them down, they actually sit fairly flush.