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-   -   [intake technical discssion] (http://forum.e46fanatics.com/showthread.php?t=927656)

bryce-o 06-14-2012 03:15 PM

[intake technical discssion]
 
Hey guys,
I've been doing some live monitoring of data on my 330ci today. Setup:

Catless technik headers
Eurocharged reflash

In stop and go driving, my IAT ranges about 20-30 degrees above ambient temperature. Highway driving is 8-10 degrees above ambient.

This is in 80-90 degree temperatures.


I know cold air intakes are touted as being the best on this platform [cosmos, dinan], but how much better are they really?

More airflow, less restriction, better efficiency, these are variables that are harder to log or compare on a N/A motor. I wish it was as easy as my twin turbo cars were, but that's not the case. So, based solely on IAT, does a true cold air intake, like the dinan long tube, provide better Performance?


Hopefully, a fellow e46fanatic is willing to measure IAT with said intake. Otherwise, I may purchase a cosmos to run tests of my own. Thoughts?

Drewfus2101 06-14-2012 04:10 PM

I've got a 'fender-well' intake with a K&N sitting right behind the fog light. When I get done with the brakes this weekend, I'll see if I can't log some IAT numbers.

Also, there is more to the short-tube vs. long-tube than just IATs. I ran a short-tube, which was just a K&N attached to the MAF for a short time. I had a heat shield too. Part throttle response was horrible and the car just never felt right. I'm pretty sure (now) that this was because there was too much turbulence in the air before it got to the MAF. So the long-tube intakes smooth all that out and the short-tubes just can't.

When I put on the long-tube, the difference was immediate. Throttle response was so much smoother. MAF data between the two would help show this, but other mods would skew the numbers between different cars.

bryce-o 06-14-2012 04:17 PM

Nice points. I was fully aware of the short ram intake issues, I've done substantial searching and reading since I've joined this forum. It would be great if we could compare IAT delta info with stock, bmw perf intake, and dinan cold air (fender well).

I'm also researching how to extrapolate flow and density data from common data log v
Channels. Will keep this thread updated with what I find.

bryce-o 06-15-2012 11:49 AM

Cooler day today, 75 degrees ambient. IAT is 6 degrees above ambient, highway driving. The stock intake appears to be very stellar at moderate outside temps. I bet 50-70 degrees outside, it'll be tough to beat

///Miller325ci 06-19-2012 01:54 PM

Dinan's airbox is basically made from the same material as the stock box... but you get more airflow and capacity...

smooth1 06-19-2012 02:45 PM

Heat soak in the engine bay is going to play a role on IATs no matter what, but those numbers are still very very good. I'd also like to see more comparisons done. I think everyone will benefit from these results being available.

OP, once I finish MS45 support in my BMWLogger application I'll be in touch with you. It would make comparing data runs immensely easier as you can record, playback, and graph the data out, as well as export to CSV for side by side comparison.

aggieE46 06-19-2012 03:17 PM

What are you using to monitor the data?

Where in TX are you? You're more than welcome to monitor the IATs on mine with my Dinan.

I've been considering wrapping it, too. We could do a before and after if you were interested.

xixixi 06-19-2012 04:43 PM

I did these test already with a gt1? Maybe an Autologic? IIRC difference from idling for around 20 minutes and the hwy was about 30 degrees. I'll try to dig up the thread. I think it was in general chat! I don't run any under shields, nothing in the the corners of the front bumper. Nothing under the front fenders. Zero under shields. No front fog, all plastic mesh removed from the front bumper. etc

bryce-o 06-21-2012 03:51 PM

Quote:

Originally Posted by ///Miller325ci (Post 14500496)
Dinan's airbox is basically made from the same material as the stock box... but you get more airflow and capacity...

thanks, i've been looking at that, but i'm not positive exactly how much more airflow and air mass you achieve with the dinan box.

Quote:

Originally Posted by smooth1 (Post 14500638)
Heat soak in the engine bay is going to play a role on IATs no matter what, but those numbers are still very very good. I'd also like to see more comparisons done. I think everyone will benefit from these results being available.

OP, once I finish MS45 support in my BMWLogger application I'll be in touch with you. It would make comparing data runs immensely easier as you can record, playback, and graph the data out, as well as export to CSV for side by side comparison.

thanks. i think heat soak will affect mainly the open filter intakes, at least the ones where the filter is still in the engine bay. the stock airbox seems to do a great job of isolating the intake air from the warmer air in the engine bay. i'm interested in your logging software, will definitely look into that once it's available

Quote:

Originally Posted by aggieE46 (Post 14500714)
What are you using to monitor the data?

Where in TX are you? You're more than welcome to monitor the IATs on mine with my Dinan.

I've been considering wrapping it, too. We could do a before and after if you were interested.

i'm in houston. i've been using the ultra gauge ($65 lol) to just observe real-time data. i use my iphone to take notes about the IAT range i've been observing.

the dinan cold air intake (long tube) is a great idea, i think it sees at least the same (probably better) IAT's than the stock box. how much better, is the question on my mind. it undoubtedly provides more air and better flow, but i haven't been able to get MAF readings to translate into those variables yet.

Quote:

Originally Posted by xixixi (Post 14500958)
I did these test already with a gt1? Maybe an Autologic? IIRC difference from idling for around 20 minutes and the hwy was about 30 degrees. I'll try to dig up the thread. I think it was in general chat! I don't run any under shields, nothing in the the corners of the front bumper. Nothing under the front fenders. Zero under shields. No front fog, all plastic mesh removed from the front bumper. etc

interesting. i know the IAT's will sky rocket under sustained idle (i've witnessed this). the highway cruising, with lots of airflow, generates pretty low IAT's compared with ambient temps (within 5-9 really, in 70-80 degree weather). ambient temps from 85-90+ result in about a 10-15 degree difference, on thh highway.

around town, the stock intake isn't as effective, as my IAT's climb to 20-25 degrees above ambient in stop and go driving, where i don't get over 40 mph

xixixi 06-21-2012 04:17 PM

I forgot to mention, my MAF has nothing between it and the filter. I gutted it, took the wire screen out and the plastic one. Might be worth knowing, I'm unable to find the general thread. Maybe Iceman can find the thread, I remember him posting in it.

smooth1 06-21-2012 05:24 PM

Quote:

Originally Posted by bryce-o (Post 14507339)
thanks. i think heat soak will affect mainly the open filter intakes, at least the ones where the filter is still in the engine bay. the stock airbox seems to do a great job of isolating the intake air from the warmer air in the engine bay. i'm interested in your logging software, will definitely look into that once it's available

You're thinking of engine bay air vs intake (Air box) inlet air. The air box does a good job separating the two, but I'm thinking about heat soak of the parts that the air actually passes through. :) I see this all the time on the dyno.

bryce-o 07-05-2012 01:19 PM

update: temps in SE texas are in the upper 90's, low 100's, will full humidity. the IAT's in the morning and evening hours are still within 5-8 degrees of ambient, while cruising on the freeway. mid-day or early afternoon, during stop and go traffic, the IAT's peak about 30 degrees above ambient. this is with very limited airflow across the front of the car. during highway cruising in these temps, the IAT's are about 10-14 degrees above ambient. i've been considering trying out a different intake (dinan or bmw performance airboxes, mainly). i like the throttle response of a closed-box intake (yes, i've driven cars with long-tube CAI's). i think the BMW performance intake or dinan airbox will provide more airflow and air mass, while maintaining low IAT's. not entirely sure about switching out the intake yet, my car is making decent power with only catless headers and a custom eurocharged flash.

jared_wiesner 07-05-2012 02:16 PM

Dinan relocates the IAT with their cold air intakes on the M5 for example. I have relocated the IAT down to the air pickup area of my long tube cold air intake. IAT temps are much more stable. Much more power off the line after idle in hot temps.

xixixi 07-05-2012 10:17 PM

Quote:

Originally Posted by jared_wiesner (Post 14544277)
Dinan relocates the IAT with their cold air intakes on the M5 for example. I have relocated the IAT down to the air pickup area of my long tube cold air intake. IAT temps are much more stable. Much more power off the line after idle in hot temps.

This is interesting. You plugged the hole in the intake and relocated the IAT from within the manifold to where? Sounds cool! :thumbsup:

jared_wiesner 07-06-2012 08:50 AM

Yep I plugged the hole in the manifold and relocated the sensor to a hole I drilled in the side of my brake cooling duct in the front bumper. IAT temps are now only 1-2 degrees higher than ambient temp outside. My long tube intake also picks up from a hole in the bumper right next to the brake duct.

I may have to move the sensor during the winter months though. I doubt it would like to be subjected to the salty water.

TxZHP04 07-06-2012 09:45 AM

Quote:

Originally Posted by jared_wiesner (Post 14544277)
I have relocated the IAT down to the air pickup area of my long tube cold air intake. IAT temps are much more stable. Much more power off the line after idle in hot temps.

The only problem with this approach is that the sensor readings are now more indicative of ambient temps than they are the intake charge entering the cylinders. While this fools the DME into allowing more timing thus producing more power, it could also result in too much timing under heat soaked conditions and increase the likelihood of detonation. Just because the sensor doesn't see it doesn't mean the heat soak doesn't still exist. You may be fine but it's definitely something you want to be aware of and monitor closely to ensure the longevity of your motor.

jared_wiesner 07-06-2012 10:26 AM

Quote:

Originally Posted by TxZHP04 (Post 14546782)
The only problem with this approach is that the sensor readings are now more indicative of ambient temps than they are the intake charge entering the cylinders. While this fools the DME into allowing more timing thus producing more power, it could also result in too much timing under heat soaked conditions and increase the likelihood of detonation. Just because the sensor doesn't see it doesn't mean the heat soak doesn't still exist. You may be fine but it's definitely something you want to be aware of and monitor closely to ensure the longevity of your motor.

Very reasonable observation. Caution is advised, however...

I thought through that very thoroughly before I relocated the sensor. Tricking the DME with a reduced air temp would be foolish. The air temp actually entering the cylinders is what is important.
Thats why I made sure my sensor is essentially inches from my air inlet.
While it seems resonable that the sensor be up in the manifold right next to the runners, the problem is that it becomes heat soaked from direct connection to the hot manifold. The air however cannot heat up from convection in the intake tract nearly as quickly as the sensor heats up from conduction.

It's pretty well known that the air is flowing in quickly enough to stay cool without heating up from convection.

So, essentially the idea is to get an accurate reading on the air temp going in, not to trick the DME.

Check out the Dinan university Dyno testing info. It's pretty interesting to see what they documented surrounding the IAT and the info it receives.

TxZHP04 07-06-2012 03:24 PM

Quote:

Originally Posted by jared_wiesner (Post 14546898)
Very reasonable observation. Caution is advised, however...

I thought through that very thoroughly before I relocated the sensor. Tricking the DME with a reduced air temp would be foolish. The air temp actually entering the cylinders is what is important.
Thats why I made sure my sensor is essentially inches from my air inlet.
While it seems resonable that the sensor be up in the manifold right next to the runners, the problem is that it becomes heat soaked from direct connection to the hot manifold. The air however cannot heat up from convection in the intake tract nearly as quickly as the sensor heats up from conduction.

It's pretty well known that the air is flowing in quickly enough to stay cool without heating up from convection.

So, essentially the idea is to get an accurate reading on the air temp going in, not to trick the DME.

Check out the Dinan university Dyno testing info. It's pretty interesting to see what they documented surrounding the IAT and the info it receives.

Sensor doesn't necessarily need to be in the intake manifold next to the runners, even BMW doesn't place it there on the MS45 cars. On MS45 cars, the IAT sensor is in the MAF sensor housing - not that far from what you have done. It really doesn't matter where the sensor is located though as the magnitude of the temperature itself is irrelevant. The sensor value is merely an input used to help determine acceptable ignition timing (and probably a few other things) so what is key is that the DME is tuned for the temperatures actually being measured. Change the temperature reference and you effectively change the tune. There's probably enough safety margin in the tune that combined with knock sensors it's not a major issue, just something to be aware of.

jared_wiesner 07-06-2012 03:47 PM

Well, I get what you saying but I respectfully disagree. The tune is designed to read proper air temp through the manifold. If your driving down the road and flushing the engine bay with cold air, its values are very close to ambient air temp. If your sitting at a stop light heat soaking the sensor its values travel artificially high.

During Dinan's dyno testing of an M5 this difference meant a loss of close to 50 horsepower between running the car on a dyno with a closed hood and the factory IAT location. That can't possibly mean the ECU was somehow taking into account the fact that the car was stopped and heat soaking and artificially giving the IAT a higher temp. It means the ECU was getting a bad value to the tune of 50 lost ponies. Even with the hood opened, relocation of the IAT resulted in a gain of 10 horse.

Again, the idea is to provide an accurate reading of the air going into the engine at all times. The location where I have my sensor gives almost the same reading as measured in the factory location at 60MPH because of the air keeping everything from heat soaking. This is what the tune is designed for. Running the engine at speed. The air when your stopped is the same temp, the sensor is just getting thrown off because its heat soaked via conduction.

The M54 location is much better in the MAF but it's still not ideal and does provide artifically high numbers after heat soak even in this spot.

bryce-o 07-23-2012 04:18 PM

another update: the stock airbox is AMAZING at reducing IAT's after hard driving and maintaining low IAT's while crusing, when the ambient temps are in the high 70's. texas was exceptionally cool over the last few weeks, with a lot of rain and clouds keeping temps down. stock airbox was within 4 degrees of ambient, during light crusing or highway driving at 70 mph.


i know this is only 25% of the equation, with more air mass and better flow making potential gains, as well. for me, i've concluded that the stock airbox is more than adequate for my needs. catless headers and a reflash, whist on the stock airbox, is good power for a n/a bmw 3.0L. i'm going to hold off on more power mods while i complete some preventative maint (cooling system, ccv, vanos, etc).

i'll explore cams and dyno tuning upon completion of those overhauls. i'm sticking with the stock airbox for as long as i can, as i'm convinced it's a well designed intake and can support higher power levels than i'm currently at.


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