CAI v. SRI...:^)
 

So....I got a second, shorter filter for my AEM CAI and I thought I'll test the differences using the DH. Here's what I found:

Acceleration differences between each? Negligible. I ran 80 km/h to 140 km/h at least 3 times with each setup, same road, same environmental conditions, same test regime. All fell in the low to mid 6 second range in 4th.

SRI ran above ambient at all times during driving around. CAI would do ambient or slightly below.

Noticeably different was stopped behaviour. The CAI would rise about 5* a minute pretty consistently. The SRI jumped ~ 30* in the same time. Both would take 10-15 seconds to return to their base temp, though, verifying that, if you're moving, the SRI does not hold heat above it's slightly elevated base temp.

So, in conclusion, the highway test data indicates no acceleration differences, when the two systems are starting at their base temp. The SRI arrangement has a very slight edge in tip-in response and doesn't die off up high rpm, as SRIs are purported to do, it's the same as the CAI up there.

However, with SRI, better run hood up in the staging lanes if you track, or use the CAI, where it doesn't matter much hood up or down.

How were you measuring temps?

I'm curious as to how your CAI was pulling in colder than ambient temps.

End of second sentence....

You're going to want to put the hood up either way at the drag strip. Check out your BATS (boosted air temps) if you don't think so. - TMIC

i hope you know unless you are doing something to cool the air off, it is physically impossible for you to pull in air cooler than ambient... seriously, writing something like that doesn't set a little flag off in your head? just... someone, explain the reasoning for that... i just want to see what you can make up to back that up lol

The guy is retarded. He failed at installing fuel pump internals- absolutely had no clue what to do with the double retainer clips if I remember correctly and he's going to run tests and do data-logging? That's just one on top of many other things. Give me a break.

Pulling in air below ambient.....

Nice to see you back again 12, maybe you can last longer than an afternoon this time, if you're a little more circumspect in your character assassination. :laughing:

Anyway, the sensor resolution is a little low on the IAT sensor, no doubt but, how about carb icing as an example of air temp drop below ambient because of moving air? Shyt man, planes can ice up many degrees above freezing due to that. Maybe that's what's leading to the reading below ambient still-air temp outside here. Now, sensor res on the outside temp sensor, who knows? All I can say is that the IAT temp dropped consistently a tiny bit under that on the CAI, when the car was moving at speed. I was definitely surprised by this as well.

FP internals installed by me still going strong...bet that's because I'm not a know-it-all, afraid to ask a simple question when needed. :fing26: Your rock is calling, 12.

If any of you tards knew anything about how to measure your own temps, rather than flaming the OP, then you would know that the car uses a different sensor and sensor location to read ambient temps. Different sensor location means that the sensors will heatsoak under different conditions, which can result in IAT reading lower than the ambient temp sensor. It doesn't mean his CAI is somehow magically icing down incoming air or anything. Hell, on cold winter mornings, I've had BAT's lower than ambient after a 10 minute drive to work.

For what it's worth, IAT temps don't mean diddly poo for a turboed car. Start reading BAT's and doing things to make them go down. That's where your real performance is. Why bother keeping the incoming air a few degrees cooler when the BAT's don't drop a bit from running a full lenth CAI. Short ram = less weight, quicker throttle response, plus it's safe for all of the idiots out there who worry/drive through standing water too.

Well, I kind of figured it had to be a sensor resolution, location issue. I just put out what I found and hoped to learn something from it. I often do learn stuff here but, the "learning conditions" aren't always what I'd call favourable.

Back to the point here, despite these sensor variations and the fact there are still some other variables I can't completely control for, I still think this collected data has a degree of validity in explaining the actual situation each type of intake imposes on the car.

So, here's a Q for Bnoon: I'm sitting in the staging lanes running for few minutes, hood closed, w. SRI and, my IAT shoots up 60 or 70 degrees say (which is totally realistic based on what I've observed here). It's gonna take 10-15 seconds to drop to it's lowest possible temp once moving, I pull up to the lights. Do you not think ingesting air that much hotter is going to negatively affect performance on that run?

moving air isn't any colder... you feel colder because it is taking the heat away from you quicker because more of that cold air is going over you.
Planes ice over because with an increase in altitude, the air becomes less dense. Air that is less dense in the same volume is colder.

Right, got that, HLR.

You can get carb icing at sea level in the right conditions. Temps between -5 and +15 are ideal, plus humidity high, load on engine high, intake velocity high. The kind of icing most relevant here, if at all, is throttle icing, caused by the reduction of pressure as the air passes through the venturi tube of the carb, b/c that has most to do with the speed of the incoming air. Fuel vaporisation icing and impact icing aren't relevant here, I don't think.

I'm just not sure I can make the link expressly between the situation that creates throttle icing and any decrease in IAT v. outside temp from CAI. I think Bnoon's explanation is more likely.

And the endless battle rages on!!!!!!!

:popcorn::horse:

This is the kind of objective data that we need. Let's not shoot the messenger because we might not like the message. I was one that originally thought CAI should theoretically have a big advantage over SRI on our platform. I have since rethought that based on experience, and had since become relatively ambivalent on the issue.

Darth has done something solid and repeatable. Others can do the same thing and should be able replicate the data because, IMHO, his testing method, including choice of rpm range and gear, reduces the likelihood of driver error. Yes, sensor location and heat soak affect results but sensor location and resolution should affect both modes equally.

Guys will draw their own conclusions and are doing so. The debate will not be over, but this really helps. To me, and it's just my own interpretation of the data, is that the differences are slight, probably do not amount to enough to favor one mode of operation over another, execpt in one small area which may not matter to many. To me the remaining significant difference is that it will take longer for the CAI to develop heat soak, but once their soaked, they will perform equally.

His results are similar to my more simple test of temp rise in the engine compartment. I found that you can quickly get a 30 degree rise under the hood with the engine idling just a few minutes compared to ambient temp measured at the left front wheel well where the CAI is located. But that simple testing didn't say anything about how quickly the underhood temps would drop once the car was underway. Darth has helped us greatly with that, regardless of any personal attacks he may have to endure.

If someone wants to step up and do the same thing measuring BAT's then they should do so. I would like to know the results. I doubt there would be much difference compared to the testing done by OP.

Personally, I will still run CAI because I think that until I hit heat soak, I do have cooler IAT's. And the relationship between IAT increase and BAT increase remains 1:1 unless you can get more efficient intercooling or other means to drop BAT's. Intercoolers are way less than 100% efficient.

IAT's do matter.

Good work, Darth

Well for one, hood closed you're going to get heat soak on the intercooler. Intercooler temps are by far more important than IAT temps because the BAT temps are what the engine will actually "see", especially WOT. If you drop your IAT temp 30 degrees with a CAI, BATs will still be uneffected and you'll still run like crap. Run your CAI with stock TMIC and let it heat soak until the fan turns on, log runs. Do the same with the short ram... You'll find neglegable differences other than the IAT. BATs will remain the same.

If you can drop the BAT's 30-100 degrees by installing an air/water intercooler or meth, then you'll get some MAJOR differences. My BAT's are within 15 degrees of ambient even in summer. CAI vs short ram made no temp differences for me at all and the short ram gives better throttle response. It was an easy decision for me.

My testing was done in summer and IAT's didn't make a bit of difference, the BAT's were the same with CAI vs short ram. Not even close to 1:1 ratio and that was before the aftermarket intercooler. It has nothing to do with the intercoolers effcient rating either, it has to do with the air going through the turbo and being compressed, which raises temps. A 30 degree IAT difference made no difference at all on my BATs.

You're violating the rules on MSF.ORG tricky, directly insulting a member, darth, make a mod aware of this. get with darksun280 or lenny127

It doesn't matter much to me really, it ain't the first time, it ain't gonna be the last I hear from this dude, I bet.

He's rockin' on my knowledge base? I just got one phrase for that..."Here's the paper"....

Interesting contentions from Bnoon. I think I'll test out that little idea too. I think I can see if different IATs affect the BAT pretty easily as, I have both of those on the same screen on my Dashhawk, don't even need to datalog. I'll look it over, do some runs and see what happens.

Either your sensors on the car aren't working properly or it's the DH.

a) Show data/proof that the sensor resolution is little low on the IAT sensor?

Planes can because they're several thousands miles up in the air and their speed of travel is much faster that of your typical MS3. Like Element said, higher in the sky, the more the air becomes dense among other things

I wish I recorded my logs from few months ago. Some were (in degree Ferrenheit)
AAT: 35, IAT: 35, BAT: 50,

Now, you can't forget to take into account modifications. Are the readings done on a fairly stock MS3 whose OEM DP/Headers are shielded beyond death? Run aftermarket headers/downpipe- and just by doing this you'll see that temps inside your engine bay have increased.

There are several tricks that can be done to lower IAT below AAT. One method pro-dragsters use is "icing". Setup a proper water/air intercooler and run an ice pack reservoir.

Other method is something called "powerwire" some plug and play fiasco that supposedly lowers the temp readings by like 20 degrees using an resistor to alter the signal being send to the PCM- therefore allowing the PCM to lowering the amount of timing....

And there are few others.



Don't assume.

This doesn't make sense. You relocate those sensors inside the engine bay anywhere you want they will still get heat-soaked which will affect your IAT- but it will not affect the IAT to a point that it will read lower than AAT.

Yeah I highly doubt that. If you had this at several times you should have recorded a log. In winter, when temps were around 20 degrees F I would be able to match my my AIT and IAT and my BAT were (the lowest in this case) just 15 degrees higher- see the numbers I gave above.

For what it's worth, IAT temps don't mean diddly poo for a turboed car. Start reading BAT's and doing things to make them go down. That's where your real performance is. Why bother keeping the incoming air a few degrees cooler when the BAT's don't drop a bit from running a full lenth CAI. Short ram = less weight, quicker throttle response, plus it's safe for all of the idiots out there who worry/drive through standing water too.[/QUOTE]

There's only so much you can do to lower BAT's.... that some of these methods are just silly and much of a hassle to see such minimum gains especially on a street car. You want bigger gains go BT. These cars aren't exactly in the big power territory- 10 sec drag cars...

Weight, throttle response are so minimal it won't even make a difference.

I guess ignorance is bliss. Calling someone retarded isn't an insult and if you consider it- fine. I'll report you and about six other users for personal attacks)

Thanks for the test, Darth Vader.

I was aiming for the CAI also, but IAT temps are negligible because of BAT which apparently the same with both intakes. I also think temps drops significantly once the car is moving past 5 mph.

Our cars perform when it's moving, not idling IMO. LOL!



What I'm about to say is somewhat off topic, but has ralation to the whole air temp subject...

I was watching the news once, it was summer, and the topic was about saving energy (electricity) in your home. One of the tip was to keep your ceiling fans on to at least a medium setting to keep the rooms at least 5 degrees cooler. It's much more cost effective than running your A/C 5 degrees cooler. Apparently, moving air molecules are cooler regardless of ambient temperatures. Same thing as "wind chill" in the winter. When air is moving, it feels colder than what it is. Anyways, I tried it and it seemed like our electric bill went down, and I've been practicing this tip until now.

I hope this helps, but just to let you know, I'm no scientist, so my logic might be flawed.

A bit more difficult to test this than I thought. I took out the car and ran it several times with normal highway IATs, then let it sit and heat up the IAT real good. Unfortunately, this also changes the BAT, of course. BAT rises more slowly so, I figured I could sneak in a hit before it got too far out of whack. Naturally, though, IATs start to drop as soon as you start to move. I could find no clear difference in acceleration when starting the maximum 20 or so hotter than cruise on IAT I could work out or starting from cruise temp. That's too close to make a difference and it's just too hard to isolate IAT from the rest of the system.

The dragstrip is the only place I can see this being an issue and, only if you're forced to sit idling for a prolonged period in staging with the hood closed, baking up IAT and the BAT. It's happened to me, some douche wiggles right in front of me and I'm next up, they gotta look at the track for a minute or two, I can't jump out and open the hood, thus both of us sit there cooking up a heat-fest under the hood.

lolwut...you think the air is more dense at higher altitudes...come on dude really...think about that....

This is the kind of shit that makes my wife roll her pretty blue eyes and call me and all of you guys fucking nerds...

CAI vs. SRI and cooler air is all bullshit. By the time the compressed air hits the piston it's at the same temperature.

The only reasoning that I can come up with to justify a CAI is that hot air needs more energy to compress than cold air but we are talking peanuts here.

^^ Did you seriously just type that in this thread ?

Internal combustion engines (ALL) do better with cooler air.... no if,and,but about it.

What's wrong with my post?

Basic Physics.
The Inlet air Temp is measured at the MAF, the pressure at the MAF is slightly less than atmospheric, if a gas is reduced in pressure, the temperature reduces also to slightly below whatever the air was when it was pulled through the filter.
It is the opposite of when the gas is compressed by the turbo, in that case as the pressure rises it is heated up, hence the inter cooler.

Agree and not debating that fact. My post made reference as to CAIs offer a SIGNIFICANT reduction in air temp. We have to consider that when the turbo compresses the air changes density and temperature, then it goes through the intercooler cooling it even more to then hit the hot piston... I don't think that a CAI or SRI makes a huge difference.

^agreed

CAI's and SRI's are less about temp (even though they are sold on this principle....) and more about removing restriction...just look at your IAT's with your stock box...if you did (like i did) you will notice that once you get going your temp is the same as ambient....same as it would be in a SRI same as it would be in a CAI....the few degrees of temp you MAY get are not going to change the performance of your car drastically...what you are doing by adding either of these things is allowing more VOLUME to be taken in allowing for the car to add more FUEL and thus more POWER.....so if they do the same thing why are there two different types? really only benefit i see of a CAI is that it doesnt heat soak...but as i stated earlier that probably wont make much of a difference.....so i went with a SRI...why? shorter pipes mean less friction loss (which again is probably very minimal anyway)...plus it is a snap to install and a hell of a lot cheaper

if you really want to gain power through decreased temps...then you need to invest in a better intercooler....simple as that

/thread

I agree.... sorry for the mix-up... glad ALMOST all are on the same page.

Sort of, and generally agree, but it is not just VOLUME, but rather and also MASS that matters when comparing CAI and SRI. Both present more volume potential than the stock air box, granted. But let's understand our terminology: volume can be the same with either CAI or SRI based on fluid dynamics flow principles depending on the pipe dimensions and the flow rate of the filter. But (here's the important point) the same volume in terms of cubic feet of air varies significantly in MASS depending on its temperature.

Cold air is denser, it has greater mass and, accordingly more oxygen molecules in the same volume unit. That's why, in theory, at least, if you can get colder air into the intake before it is compressed by the compressor wheel of the turbo, colder air will exit into the intercooler. When the IC's efficiency ratio, let us say 70% is then applied, bringing the BAT temps down by 70%, you still end up with colder air going into the engine if you had colder IAT's at the start.

I say this in theory only, because I think it has been established here that the IAT's recover quickly on our car when the intake is run in SRI mode and the difference is only noticable for maybe the first 10-15 seconds after a stationary car starts to move. That will be irrelevant for most purposes except for when a CAI equipped car has not reached heat soak and the SRI car has. This might be important at the drag strip under limited circumstances when you can't keep your hood open. Probably more theoretical than real and maybe not worth the time to discuss.

Just wanted to clarify that it is total air MASS and not merely volume we should be looking at when comparing the two modes of operation at any given point in time of a WOT run.

^totally understand

in my statement i was comparing the CAI and SRI vs the stock air box...you are gaining volume over the stock air box...but yes mass flow is different between the SRI and CAI

thanks for the data. its been tested before but its always nice to do it for yourself and to confirm it.

its entirely possible for the DH to read intake temp below ambient just because the sensors are in different locations... that's not to say that the intake temp is ACTUALLY lower than ambient..the DH is just reporting what the sensor is seeing, at that location.

clearly douchey12inch is just trying to start shit and argue with darth...which of course he failed at doing, while also claiming "higher in the sky, the more the air becomes dense among other things" lawls

Data like that is pretty much almost common-sense. Plus, I didn't realize that there's just so much room to relocate these sensors just so they could read differently (will probably never read IAT below AAT to begin with) and if they do by any chance- will hardly make such a significant impact.

You don't say? Thank you for pointing out the obvious.

Clearly, I'm not here to start shit.

In regards to density/altitude- oppps, did I say that- I meant that on the contrary. Excuse my blunder.

Damn... I wonder how this conversation would go if we were all high and drunk.

It does make sense because the sensors are in different locations, hence will heat soak at different rates.


No doubt about it. My air/water would hold on to overnight temps because water heats up slower than air. Water temps were always lower than ambient temps in the early morning when IAT and AAT were near 40 degrees, water temps and BAT would still be at much cooler 15-20 degree temps. Logged DashDAQ logs and posted them a long time ago.

Wrong. Dropping BAT's is worth a LOT of HP, especially on a street car. Just by increasing the air density, let alone being able to run more boost due to detonation resistance. Absolute temperature = temperature + 459.6. Using 29 Hg" for this example, the air density at bat temps of 130 degrees is .0652 lbs. per cubic foot. Now if you drop bats by 40 degrees the air density is .0713 lbs. per cubic foot This is an improvement of 9.3%! A 300 HP engine will gain 27.9 HP from air density alone!!! The turbo will spool quicker and you can run another pound or two of boost without pre ig... Now, when I had stock TMIC, BATs were 150-180 in the summer around town. With air/water I have BATs within 15 degrees of ambient at worst, a drop of up to 100 degrees in some of my logs. Dyno 301/320 with a BAT of 98 degrees on an 89 degree day hood closed with a fan blowing on the HE.

[quote=bnoon;501983]It does make sense because the sensors are in different locations, hence will heat soak at different rates.

Yes, it will heat soak at different rates, but not much of a difference if your still running air/air inter-cooler.

Ah, I wasn't referring to air/water cooling but air/air so there will be still a big difference. I'm not disapproving with what you're saying here.


You can get these HP gains going different routes as well and similar bat temp reductions but obviously will end up being more expensive in the long terms than just going with a air/water cooler. Obviously, reduction in BAT's is what's a concern here and going with air/water cooling will out perform a air/air cooling system. If I'm not mistaken the cooling ratio of water/air is like 4-1 where as air/air is 1-1. It's also cost effective in the long term but you run higher risk of over-heating the water if something goes wrong.

Like I said, I'm not disagreeing or arguing with what you said here because all are valid points. My fault, thought, I should have mentioned that I was referring to air/air cooling.

is the pressure really that much lower though to actually change the temp by even a degree? Does the DH measure the pressure at the MAF? If so i'll go out and measure them and tell you guys the difference in temp that lower pressure will make, very simple equation, just PV=NRT. I've driven in below 20 degree weather and so far i have yet to see colder IAT than AAT. I've had a BAT match IAT for a min or so, and stay within 10 degrees for a few miles, but nothing ever below AAT.

Whatever, not trying to start anything. Really make a difference? obviously the one guy made a typo in dense air higher up, who ever said the thing about msf rules against insulting others is an idiot. If that is a rule and were it enforced i think msf would be down to... oh, noone very quickly.

fun convo lol

Well dont forget too, 2 different sensors 2 different cars, I dunno what the margin of error is on these sensors.

Seriously, I dont care, the sensors are different, different cars, basically a waste of time comparing unless there is a gross difference, when you start comparing a couple of degrees, its a waste of time.

bnoon (obviously) is running a water/air inter-cooler and the majority are running air/air cooling system- TMIC or FMIC. Obviously, huge differences in regards to heat-soak. If you're running a water/air cooler it's possible to get your IAT cooler than AAT. If you're running an air/air cooler it's not possible to get your IAT to go below AAT UNLESS some trickery is done- which I mentioned earlier. Due to the conditions at the drag strip pro dragsters implement an "ice box" reservoir with their water/air cooler to get their IAT below AAT.

Regarding your question about DH measuring pressure- I couldn't find the parameter, if it could read pressure in general it's possible it could read it on other vehicles.

I want to quote bnoon again:

Air/water cooling is a bit "extreme" for the average Joe. Most will either upgrade their TMIC or switch to a FMIC. Like stated earlier those extra "27.9 horses" could be gotten from somewhere else. There are other means of counteracting detonation that will allow you to run more boost as well.

Again, getting that additional pound of boost without pre ignition could be gotten from somewhere else and you're still limited by other factors that would otherwise make that extra lb or two of boost relevant.

This whole thing with quicker throttle response by going with a SRI- you sure it's not a placebo affect more than anything? Regardless, the difference is so minimal that unfortunately it just won't make any sort of difference compared to the same vehicle running a CAI.

Someone I think scoffed when I said there's a chance that the sensors might be malfunctioning- which obviously is quite possible.

Today on my way to work the DH displayed the following:
AAT: 78 F
IAT: 78-89 F
BAT: 98-140 F

Actual outside temp was 81 degrees F this was in the city, stop and go traffic running air/air cooling- FMIC. With this setup in 80+ degree weather my BAT's (on average) are within 40-50 degrees of AAT. From time to time they might peak up to 60 or so but obviously go down quickly the second the car starts moving.

In winter, on days when we were in 20-30 degree F days my temps would like:
AAT: 28
IAT: 28
BAT: 45-58

Like Element said, I too, would be able to match my BAT's with my AAT for quite some time.

Going back to today, I made a quick stop at the post office. I was already driving for about 45 min and my AAT was around 78-79 F. When I left the post office, about 10 min into the drive, I noticed that my AAT rose to 100-109 degrees F . Yeah, there's no way that we were even close to those temps. I thought it might have been a temp glitch in the DH so I unplugged/plugged it and same- next to check if the sensor is corrupt. Despite the AAT (incorrectly) hitting 109 degrees F- BAT and IAT were in their normal temp readings.