Drivetrain IC Airflow Question
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Joined: Mar 2006
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From: Northampton MA
Originally Posted by inimmini
I finally made a couple of attempts to measure the effect of the IC diverter shown in post #216 on the IC efficiency. Rather than pierce the boots, I found I could just loosen the clamps and slide the thermocouple wires inside the inlet and outlet IC joints (see pic).
On my first attempt, I had very little time, so I couldn't go too far from home. I decided to take some readings under brisk but brief acceleration, up to about 5500 rpm in 3rd gear. This proved to be difficult, as the inlet air temp to the IC is highly dependent on boost, which in turn is pretty sensitive to the right foot on the gas pedal. I made 7 runs with the stock diverter first, and as the engine warmed up, the max in/out temps steadily increased from 186/95 (F) to 220/107. Even so, the IC efficiency held nearly constant in the 77 to 80% range - quite a bit higher than I expected. Air temp was 73 F. I only got 3 runs in with the new diverter, ranging from in/out of 202/111 to 214/104. This gave efficiencies of 72 to 78%, or no better than stock.
I suspected that the short, transient test may be strongly influenced by the heat capacity of the IC itself, rather than heat transfer ability to air. So, tonite I made some runs on a highway at 65 mph in 5th gear. On some long gentle hills, boost was running 10mm Hg vac, outdoor air temp 86 F. Stock diverter efficiency ranged from 55 to 68%, typically with inlet air temp of around 125 F, outlet 102 F (59% eff). After switching to the new diverter, inlet air temps had gone up to 128-129 F, apparently due to heat soak while I made the switch. Outlet temps, though were 98 - 99 F, or around 70% efficiency. The SC cooled off a bit after driving for ~ 5 min, and the last reading with the new diverter was 125/94 (79% eff), which I believe is the most directly comparable number to the stock diverter tests.
Overall, I'm satisified that the effort on re-working the diverter paid off. A home made diverter might truly be the most overlooked bang-for-the-buck mod! I believe I can still get a bit more air into the scoop by cutting back on the black inner plastic piece, which narrows the inlet more than it needs to.
On my first attempt, I had very little time, so I couldn't go too far from home. I decided to take some readings under brisk but brief acceleration, up to about 5500 rpm in 3rd gear. This proved to be difficult, as the inlet air temp to the IC is highly dependent on boost, which in turn is pretty sensitive to the right foot on the gas pedal. I made 7 runs with the stock diverter first, and as the engine warmed up, the max in/out temps steadily increased from 186/95 (F) to 220/107. Even so, the IC efficiency held nearly constant in the 77 to 80% range - quite a bit higher than I expected. Air temp was 73 F. I only got 3 runs in with the new diverter, ranging from in/out of 202/111 to 214/104. This gave efficiencies of 72 to 78%, or no better than stock.
I suspected that the short, transient test may be strongly influenced by the heat capacity of the IC itself, rather than heat transfer ability to air. So, tonite I made some runs on a highway at 65 mph in 5th gear. On some long gentle hills, boost was running 10mm Hg vac, outdoor air temp 86 F. Stock diverter efficiency ranged from 55 to 68%, typically with inlet air temp of around 125 F, outlet 102 F (59% eff). After switching to the new diverter, inlet air temps had gone up to 128-129 F, apparently due to heat soak while I made the switch. Outlet temps, though were 98 - 99 F, or around 70% efficiency. The SC cooled off a bit after driving for ~ 5 min, and the last reading with the new diverter was 125/94 (79% eff), which I believe is the most directly comparable number to the stock diverter tests.
Overall, I'm satisified that the effort on re-working the diverter paid off. A home made diverter might truly be the most overlooked bang-for-the-buck mod! I believe I can still get a bit more air into the scoop by cutting back on the black inner plastic piece, which narrows the inlet more than it needs to.
The diverter, especialy the OE unit, is not very efficient. Recovery time is, IMHO, the first step to building the "better mouse trap".
Remove the OE unit in the hood & see what you get. As the car sits after a run, there is more area for heat to exit, also more air to cool things down when you decide to make another run. The IC does not benifet much but the rest of the under hood does. This may help you with the "Ultimate Diverter Design", UDD for short.
6th Gear
Joined: Sep 2002
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From: Hampton, VA
Originally Posted by stevecars60
Nice Job
The diverter, especialy the OE unit, is not very efficient. Recovery time is, IMHO, the first step to building the "better mouse trap".
Remove the OE unit in the hood & see what you get. As the car sits after a run, there is more area for heat to exit, also more air to cool things down when you decide to make another run. The IC does not benifet much but the rest of the under hood does. This may help you with the "Ultimate Diverter Design", UDD for short.
The diverter, especialy the OE unit, is not very efficient. Recovery time is, IMHO, the first step to building the "better mouse trap".
Remove the OE unit in the hood & see what you get. As the car sits after a run, there is more area for heat to exit, also more air to cool things down when you decide to make another run. The IC does not benifet much but the rest of the under hood does. This may help you with the "Ultimate Diverter Design", UDD for short.
My stock Upper diverter has been out for a while as well.
But whatrt you are suggesting will lead to removing any sealing around the top side of the IC allowing air to just pass over and not be forced through.
Am I getting this right?
My little dose of LITHIUM
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Joined: Jul 2005
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From: Albuquerque New Mexico
I interpret Steve's comment as follows: At rest, removing the stock bonnet diverter panel increases the area that can radiate heat away from the IC. At speed, removing the stock bonnet diverter allows a greater volume of air to be forced into the IC. There's no doubt, from my photos and otherwise, that the Alta diverter makes a very good seal against the underside of the bonnet with the stock bonnet diverter removed (the paint on the underside of the bonnet is being removed by the Alta seals at a pretty rapid and constant rate!)
I stand to be corrected.
I stand to be corrected.
6th Gear
Joined: Mar 2006
Posts: 1,710
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From: Northampton MA
Originally Posted by gandini
I interpret Steve's comment as follows: At rest, removing the stock bonnet diverter panel increases the area that can radiate heat away from the IC. At speed, removing the stock bonnet diverter allows a greater volume of air to be forced into the IC. There's no doubt, from my photos and otherwise, that the Alta diverter makes a very good seal against the underside of the bonnet with the stock bonnet diverter removed (the paint on the underside of the bonnet is being removed by the Alta seals at a pretty rapid and constant rate!)
I stand to be corrected.
I stand to be corrected.
The BMW design, OE diverter, does work, but it is only designed to force air through the IC. I have seen as much as 12 minutes quicker, under hood temp recovery, without the OE diverter ( or any diverter for that mater ). Yesterday was a good example, 103 in the sun, over 100 in the shade ( closer to 15 minutes ). The car needs to be moving at 20 -25 mph to see temps drop off. Yesterday was a good test day ( had the day off - sweated my a## off ), but things that required a chain saw, axe, shovel, picking up 100's of bales of hay, not so good.....
IMHO, the Alta diverter is the best low cost solution for both, recovery & under hood temp reduction ( unless you join the DIY club ). To do both, reducing under hood heat & force air to the IC, the Alta does a pretty good job. On the other hand........DFIC rules
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Joined: Feb 2006
Posts: 437
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From: Greenville, SC
About the rubbing that the Alta div does.... could you not use some thin weather stripping (foam w/sticky backing) material and make a kind of cushion between the rubber on the Alta and the bonnet paint?
Also, Gandini, when you were looking to buy the RamAir scoop, did you also, look at the Extreme scoop? I am guessing that you were looking to keep the appearance of the stock mail slot, but wanted more air. I am looking to get the most air..... it was wicked hot here yeaterday and it's going to be worse they say today. So looks are second on my list. With that said, it looks that you have one of the better solutions. I think that the extension on the front - that closes the gap is part of the trick/solution also.
Thanks everyone for their ideas!
Also, Gandini, when you were looking to buy the RamAir scoop, did you also, look at the Extreme scoop? I am guessing that you were looking to keep the appearance of the stock mail slot, but wanted more air. I am looking to get the most air..... it was wicked hot here yeaterday and it's going to be worse they say today. So looks are second on my list. With that said, it looks that you have one of the better solutions. I think that the extension on the front - that closes the gap is part of the trick/solution also.
Thanks everyone for their ideas!
6th Gear
Joined: Mar 2006
Posts: 1,710
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From: Northampton MA
"About the rubbing that the Alta div does.... could you not use some thin weather stripping (foam w/sticky backing) material and make a kind of cushion between the rubber on the Alta and the bonnet paint?"
The hood is aluminum with the thinest paint job I have ever seen ( under hood ). Not to worry, the weather strip won't wear through the hood.
The hood is aluminum with the thinest paint job I have ever seen ( under hood ). Not to worry, the weather strip won't wear through the hood.
6th Gear
Joined: Sep 2002
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From: Hampton, VA
Originally Posted by stevecars60
You are correct.
The BMW design, OE diverter, does work, but it is only designed to force air through the IC. I have seen as much as 12 minutes quicker, under hood temp recovery, without the OE diverter ( or any diverter for that mater ). Yesterday was a good example, 103 in the sun, over 100 in the shade ( closer to 15 minutes ). The car needs to be moving at 20 -25 mph to see temps drop off. Yesterday was a good test day ( had the day off - sweated my a## off ), but things that required a chain saw, axe, shovel, picking up 100's of bales of hay, not so good.....
IMHO, the Alta diverter is the best low cost solution for both, recovery & under hood temp reduction ( unless you join the DIY club ). To do both, reducing under hood heat & force air to the IC, the Alta does a pretty good job. On the other hand........DFIC rules
The BMW design, OE diverter, does work, but it is only designed to force air through the IC. I have seen as much as 12 minutes quicker, under hood temp recovery, without the OE diverter ( or any diverter for that mater ). Yesterday was a good example, 103 in the sun, over 100 in the shade ( closer to 15 minutes ). The car needs to be moving at 20 -25 mph to see temps drop off. Yesterday was a good test day ( had the day off - sweated my a## off ), but things that required a chain saw, axe, shovel, picking up 100's of bales of hay, not so good.....
IMHO, the Alta diverter is the best low cost solution for both, recovery & under hood temp reduction ( unless you join the DIY club ). To do both, reducing under hood heat & force air to the IC, the Alta does a pretty good job. On the other hand........DFIC rules
Yes you may dissipate heat better under static conditions but you will sacrifice a lot under motion.
I have posted details elsewhere but basically I left a large gap ( ooops ) in the rear seal once and couldn't figure out why my IC was running higher outlet temps. Efficiency had dropped ~ 5%.
The alta style does well but I don't like something covering the IC with the hood open. Vanity really. I like showing off the nice big IC I paid good money for.
As far as the DFIC...well...we'll see.
Bonnet diverter
I'm also not convinced that removing the bonnet diverter is a good thing. I agree with Obehave that under motion, the ramps in the bonnet diverter should help force air thru the IC better than having a large open space over the IC. In the latter case, a vortex could form that prevents flow thru the IC. At rest (heat soak condition), the large head space probably does promote some convection currents that help dissipate heat better than if the bonnet diverter were in place, but I can't see how this would make much of a difference since the small scoop opening still blocks access to fresh air.
I think if the bonnet diverter is removed, the IC diverter has to have very tall vanes to grab the air and prevent the head space from simply becoming a re-circulation zone.
I think if the bonnet diverter is removed, the IC diverter has to have very tall vanes to grab the air and prevent the head space from simply becoming a re-circulation zone.
6th Gear
Joined: Mar 2006
Posts: 1,710
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From: Northampton MA
Originally Posted by obehave
I agree with improving the diverter I was just questioning removing the OEM unit and not replacing it with something. Just removing it is not a good idea.
Yes you may dissipate heat better under static conditions but you will sacrifice a lot under motion.
I have posted details elsewhere but basically I left a large gap ( ooops ) in the rear seal once and couldn't figure out why my IC was running higher outlet temps. Efficiency had dropped ~ 5%.
The alta style does well but I don't like something covering the IC with the hood open. Vanity really. I like showing off the nice big IC I paid good money for.
As far as the DFIC...well...we'll see.
Yes you may dissipate heat better under static conditions but you will sacrifice a lot under motion.
I have posted details elsewhere but basically I left a large gap ( ooops ) in the rear seal once and couldn't figure out why my IC was running higher outlet temps. Efficiency had dropped ~ 5%.
The alta style does well but I don't like something covering the IC with the hood open. Vanity really. I like showing off the nice big IC I paid good money for.
As far as the DFIC...well...we'll see.
Vanity??? No, I'de do the same thing.
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Joined: Sep 2002
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From: Hampton, VA
Originally Posted by stevecars60
Yes you do sacrifice some IC air under motion without the OE diverter, no argument here. The big thing is, when removed, the under hood temps drop quicker thus making better descisions as to how to control IC air as well as the rest of the underhood. Like you say, you loose 5% which in the big picture is not a lot considering how hot the rest of the system is, radiator, block, exhaust..... IMHO, if you can reduce heat the whole system will make more power. I'll bet your mod allows more cooling overall than the OE piece with the added benifet of better air to the IC, even with your big IC.
Vanity??? No, I'd do the same thing.
Vanity??? No, I'd do the same thing.
Bear in mind though that the 5% I mentioned is based on steady state cruise measurements and may have a larger impact under hard driving conditions.
It also equates to 10-15ºF range. An 11ºF change alters HP by 1%. Once again all of this under steady state cruising. I'm quite certain the impact under hard acceleration would be greater. It may only be 2-5 HP( no I don't have a 500 HP MINI) but it's HP I'm not giving away
This kind of brings back the age old "what to do when you're stopped" discussion. Water, CO2, fans, a little door that pops open on the hood, all the above...
6th Gear
Joined: Mar 2006
Posts: 1,710
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From: Northampton MA
Originally Posted by obehave
The downside to this discussion is it would be very hard to do back to back tests to measure rise time, return to stable temp time, etc to see which is the most beneficial. Kind of a bummer really.
Bear in mind though that the 5% I mentioned is based on steady state cruise measurements and may have a larger impact under hard driving conditions.
It also equates to 10-15ºF range. An 11ºF change alters HP by 1%. Once again all of this under steady state cruising. I'm quite certain the impact under hard acceleration would be greater. It may only be 2-5 HP( no I don't have a 500 HP MINI) but it's HP I'm not giving away
This kind of brings back the age old "what to do when you're stopped" discussion. Water, CO2, fans, a little door that pops open on the hood, all the above...
Bear in mind though that the 5% I mentioned is based on steady state cruise measurements and may have a larger impact under hard driving conditions.
It also equates to 10-15ºF range. An 11ºF change alters HP by 1%. Once again all of this under steady state cruising. I'm quite certain the impact under hard acceleration would be greater. It may only be 2-5 HP( no I don't have a 500 HP MINI) but it's HP I'm not giving away
This kind of brings back the age old "what to do when you're stopped" discussion. Water, CO2, fans, a little door that pops open on the hood, all the above...
Bottom line, when stopped there's not much you can do. Alta's solution works with the water. The downside is it only lasts as long as you have water. The under hood scoop I made works but the Alta with water works better ( as far as recovery & direct air on the IC the contraption, at speed, works as well as or better - it's on the bench for the next step ). I believe that we can have a passive solution that will work and a piece that most of us can DIY without $$$ of tools.
Just because, I put some IK24's in yesterday. In this state the only gas you can get has 10% eth. I put about 100 miles on yesterday at 103d & another 100 today at 96d.... runs better than w/ the 22s. Interesting
6th Gear
Joined: Sep 2002
Posts: 2,196
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From: Hampton, VA
Originally Posted by stevecars60
snip....
Just because, I put some IK24's in yesterday. In this state the only gas you can get has 10% eth. I put about 100 miles on yesterday at 103d & another 100 today at 96d.... runs better than w/ the 22s. Interesting
Just because, I put some IK24's in yesterday. In this state the only gas you can get has 10% eth. I put about 100 miles on yesterday at 103d & another 100 today at 96d.... runs better than w/ the 22s. Interesting
Pretty much the same weather here.
MIght have to try that. Thanks.
3rd Gear
Joined: Jul 2005
Posts: 163
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From: Forked River, NJ
Originally Posted by stevecars60
"About the rubbing that the Alta div does.... could you not use some thin weather stripping (foam w/sticky backing) material and make a kind of cushion between the rubber on the Alta and the bonnet paint?"
The hood is aluminum with the thinest paint job I have ever seen ( under hood ). Not to worry, the weather strip won't wear through the hood.
The hood is aluminum with the thinest paint job I have ever seen ( under hood ). Not to worry, the weather strip won't wear through the hood.
6th Gear
Joined: Mar 2006
Posts: 1,710
Likes: 1
From: Northampton MA
Originally Posted by lambspeed
Unless their has been a change, The hood is steel. Aluminum would be nice though.
Aluminum is 1 of my favorite materials.......
I tried to read most of this thread, but might have missed something along the way. I did not see anyone mention a quick trick to help air flow through the IC. First remove the IC screws. Add a couple of washers under the IC where the screws go (long ones). Then Add a couple of washers to the front screws of the IC. ON top. This pushes the back of the IC up and pushes the front of the IC down. This helps the air to flow better through the IC. It is a minor change but you will notice the angle change. If you use this with your modifications developed here, you will have to adjust the height of the seals to the bonnet. There is a limit on how much you can do this, the IC starts to rub agains the metal surface below the IC. I also do not use the IC plastic cover with this modification. Enjoy.
Bomboasy
Bomboasy
Originally Posted by bomboasy
I tried to read most of this thread, but might have missed something along the way. I did not see anyone mention a quick trick to help air flow through the IC. First remove the IC screws. Add a couple of washers under the IC where the screws go (long ones). Then Add a couple of washers to the front screws of the IC. ON top. This pushes the back of the IC up and pushes the front of the IC down. This helps the air to flow better through the IC. It is a minor change but you will notice the angle change. If you use this with your modifications developed here, you will have to adjust the height of the seals to the bonnet. There is a limit on how much you can do this, the IC starts to rub agains the metal surface below the IC. I also do not use the IC plastic cover with this modification. Enjoy.
Bomboasy
Bomboasy
Did you notice any improvements by tilting the IC? How thick of a build up are you using? Are you using stock or aftermarket IC rubber boots? Any sealing problems?
JS
Originally Posted by bomboasy
I tried to read most of this thread, but might have missed something along the way. I did not see anyone mention a quick trick to help air flow through the IC. First remove the IC screws. Add a couple of washers under the IC where the screws go (long ones). Then Add a couple of washers to the front screws of the IC. ON top. This pushes the back of the IC up and pushes the front of the IC down. This helps the air to flow better through the IC. It is a minor change but you will notice the angle change. If you use this with your modifications developed here, you will have to adjust the height of the seals to the bonnet. There is a limit on how much you can do this, the IC starts to rub agains the metal surface below the IC. I also do not use the IC plastic cover with this modification. Enjoy.
Bomboasy
Bomboasy
Thread here...
https://www.northamericanmotoring.co...ad.php?t=72261
Originally Posted by PARTSMAN
I did something similar to this except I cut the ends of the IC, tilted it, and welded it back together.
Thread here...
https://www.northamericanmotoring.co...ad.php?t=72261
Thread here...
https://www.northamericanmotoring.co...ad.php?t=72261
Sorry, I don't see where you cut and welded in the photos.
JS
Originally Posted by JS
Juaquin,
Sorry, I don't see where you cut and welded in the photos.
JS
Sorry, I don't see where you cut and welded in the photos.
JS
I put the IC in a horizontal band saw and followed the "square" of the IC, basically slicing off the ends that go into the boots. I didn't go all the way as to slice them completely off, just enough to tilt it.
It will be coming off pretty soon though, as I will be cutting up all the stock ones I have to re-configure so that the ambient flows front to back.
IK-24s
Originally Posted by obehave
Nobody carries them locally
Need to order them on line. Any good pricing suggestions?
Need to order them on line. Any good pricing suggestions?
Matt
6th Gear
Joined: Mar 2006
Posts: 1,710
Likes: 1
From: Northampton MA
52o this morning, with the 24s the car starts just as it did with the stock & the IK22s. So far 300m & this car realy likes the 24s best. Only time will tell but so far, it's all good.
Obe, I got the plugs from an import car parts place. Ordered & got them the next day. For the 4, it was about $46 including tax.
Obe, I got the plugs from an import car parts place. Ordered & got them the next day. For the 4, it was about $46 including tax.