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Strange enough warmer air produces better MPG numbers though... :smart:http://mopar.mopar1973man.com/cummins/2ndgen24v/mpg-fooler/mpg-fooler.htm Colder air tend to reduce MPG's... :stuned:

Don't make it sound like something that it is not. Whether the air is cold or hot the mileage should remain the same, the fact that VP44 trucks like to do their antics during winter is not the same thing. As for a heat shield, I have a temperature probe zip tied to the BHAF. It seems that if water freezes outside, there is basically no difference. As ambient rises, there starts to be a difference ranging from maybe 5-10* higher than ambient when ambient is 50-80F. 80*+ gets around 10-15* rise. Pulling a trailer will yield 5-10* higher than the unloaded readings, maybe even higher. EGT's and the BHAF temp correlate very closely with each other as the exhaust manifold seems to radiate a lot of heat which is seen in the BHAF temps. Consequently, pulling a trailer raises EGT's which in turn raises the BHAF intake temp. As for engine operation, I notice when temps get to 10 below my truck really flys. When it gets really hot, my truck is obviously not as happy. If I had to guess, I would say -10F produces 10 more HP than at 100F. I really don't think it is noticeable enough to make a note of and go out of your way to make intake temps as cold as possible. A 20* difference isn't going to make a difference big enough (or at all) to offset the cost of whatever you did to make them lower. I calculated it once and there is hardly any difference in the heat of compression when comparing even -10F to 100F, though the air at -10 is more dense so you get more air to burn the fuel in. Don't mistake that for why it won't start in the morning, the engine block is freezing and takes all that heat away..
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yeah. waht he said i think. i have seen more power in colder weather with and without the bhaf. it only lasts until the engine warms in my case. and then just returns to normal. egts pretty much the same winter or summer. i am sure if i collected alot of data that ther would be a diffarence, but i think it would be matginal at best. again my:2cents:

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  • Owner

Not enclosing the BHAF, will that increase the exhaust temps?

under daily driving mine have not changed and i have no heat sheild at all.

I didn't see any change really stock air box and BHAF... Just the BHAF breathed better and didn't leak dirt into the system.

Don't make it sound like something that it is not. Whether the air is cold or hot the mileage should remain the same, the fact that VP44 trucks like to do their antics during winter is not the same thing. As for a heat shield, I have a temperature probe zip tied to the BHAF. It seems that if water freezes outside, there is basically no difference. As ambient rises, there starts to be a difference ranging from maybe 5-10* higher than ambient when ambient is 50-80F. 80*+ gets around 10-15* rise. Pulling a trailer will yield 5-10* higher than the unloaded readings, maybe even higher. EGT's and the BHAF temp correlate very closely with each other as the exhaust manifold seems to radiate a lot of heat which is seen in the BHAF temps. Consequently, pulling a trailer raises EGT's which in turn raises the BHAF intake temp. As for engine operation, I notice when temps get to 10 below my truck really flys. When it gets really hot, my truck is obviously not as happy. If I had to guess, I would say -10F produces 10 more HP than at 100F. I really don't think it is noticeable enough to make a note of and go out of your way to make intake temps as cold as possible. A 20* difference isn't going to make a difference big enough (or at all) to offset the cost of whatever you did to make them lower. I calculated it once and there is hardly any difference in the heat of compression when comparing even -10F to 100F, though the air at -10 is more dense so you get more air to burn the fuel in. Don't mistake that for why it won't start in the morning, the engine block is freezing and takes all that heat away..

Didn't mean that but I should of explained better... When the VP44 seem to hit the high point of MPG's is right at about 100*F IAT temps. Below this the MPG's tend to fall and performance curve starts to increase HP. As for increase of EGT's I really don't see a change from using the stock box plumbed to outside air to BHAF. Now of course looking at EGT's between summer and winter it changes outside temp do have a factor of cooling the air in the intercooler even more (hence it design purpose). So the air at the BHAF might be warm but if you not using a winter front in the dead cold of winter then the air in the manifold will be roughly +40* to +50*F over outside. In the summer I see roughly +30* to +40*F on the IAT. So on a 104*F day I see 130*F in the manifold. But on a 0*F day I will see roughly 45*F in the manifold. But the fact remain the mainfolds on the 24V do have a coolant passage in it heating the air again so... :shrug: The 1/2" pipe plug just forward of the IAT sensor is a coolant passage... So just remember the air inhaled and compressed is heated... Then it cooled by the intercooler and then heated again by the coolant passage in the head... Can't win for losing... :rolleyes:
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I didn't see any change really stock air box and BHAF... Just the BHAF breathed better and didn't leak dirt into the system.

Didn't mean that but I should of explained better... When the VP44 seem to hit the high point of MPG's is right at about 100*F IAT temps. Below this the MPG's tend to fall and performance curve starts to increase HP. As for increase of EGT's I really don't see a change from using the stock box plumbed to outside air to BHAF. Now of course looking at EGT's between summer and winter it changes outside temp do have a factor of cooling the air in the intercooler even more (hence it design purpose). So the air at the BHAF might be warm but if you not using a winter front in the dead cold of winter then the air in the manifold will be roughly +40* to +50*F over outside. In the summer I see roughly +30* to +40*F on the IAT. So on a 104*F day I see 130*F in the manifold. But on a 0*F day I will see roughly 45*F in the manifold. But the fact remain the mainfolds on the 24V do have a coolant passage in it heating the air again so... :shrug: The 1/2" pipe plug just forward of the IAT sensor is a coolant passage...

So just remember the air inhaled and compressed is heated... Then it cooled by the intercooler and then heated again by the coolant passage in the head... Can't win for losing... :rolleyes:

i dont have all the data that mike has gathered. it is interesting to see it though. but you can pretty much feel the truck behaving this way when it is driven. in the seat of your pants.

--- Update to the previous post...

Are any of you running a bhaf with an aftermarket turbo ?

stock hx35 here

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I have a 6" inlet amsoil filter and a filter wrap thingie. With that sock wrap thingamajig i cant see any dirt getting in. I also have a bhaf that i tryed from napa. It seemed like it didnt flow as well. My turbo is a 64 and thats not real big. Maybe i should test it somehow with egt amd mpg ?

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  • Owner

I also have a bhaf that i tryed from napa. It seemed like it didnt flow as well.

Just stick the filter minder in the head of the BHAF and you'll know if its restrictive or not. The filter minder works from water column not mercury column so to pull the filter minder full span takes a very little amount of vacuum no more that sucking 44oz drink straw. Seriously...
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  • 1 month later...

Just installed my BHAF tonight and decided to do a heat shield. The BHAF hits just a bit on the hood insulation but doesn't seem to be hurting it. Two things I wanted to ask.....seems that it takes more acceleration to make boost now, does that seem correct? Also, any need of running the filter mnder and if so how does it come out of the stock air box? I can't seem to get it out by trying to pull it out, sure i'm just missing something tho :shrug:

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  • 2 weeks later...
:cool::hyper:Thanks Mike for the link. Just got one installed with cover for prescreen. Awsome deal. Looks great in ther truck. Glad to finally get the K n N out of truck so buddies will quit ribbing me about it. Question do you know/think Ca. smog will have a problem with it.
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:cool::hyper:Thanks Mike for the link. Just got one installed with cover for prescreen. Awsome deal. Looks great in ther truck. Glad to finally get the K n N out of truck so buddies will quit ribbing me about it. Question do you know/think Ca. smog will have a problem with it.

No you should have any problems with CA smog and your air filter becasue you do not move the stock location of the IAT sensor.
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