How well does a cowl indution hood work? I have never understood exactly how. I have a ram air style cowl induction hood and was considering cutting out the ram air hole to let air in but I figured if the cowl induction works to let air in over the engine I would leave it.
bigblackdmax
- Status
How cowl induction works?
The base of the windshield is a high pressure area at speed. Cowl induction just puts an opening to let that high pressure air "escape" into the back of the hood.
Sorry to contradict but there is no high pressure area at the base of the windsheild. Just like an airplane wing air must pass over and under the truck. The air passing over must travel faster and farther the the air underneath. Now compared to the front of the truck that breaks the wind this creates a vaccum (this vaccum is how wings create lift). Near the wipers there is accutually a low pressure area due to the fact that the air "drops" over the raised portion of the cowl. Cowl induction (term is misleading) works by "sucking" out the hot air from under the hood near the windsheild and as a result more cold air is drawn into the engine comparment from the front of the vehical. The engine bay acts more like a tunnel and there is more fresh air passing through the engine compartment. This helps two fold, for both cooling and fresh air for the engine to breath.
See this website for a better explaination
http://www.limboland.net/Merchant2/...2/merchant.mvc?Screen=PROD&Store_Code=pt&Product_Code=PZH101F&Category_Code=EBP
Ram Air is a little different, it has the opening at the front of the vehical where there is a high pressure area and grabs the high velocity air which helps to push air into the air box just before the filter. This helps to reduce the pressure differential across the filter and therefore reducing the effort that the engine must use to drawn air into itself.
I was thinking of installing a cowl hood on my truck but since I never see temps above 100'C or 212'F during the summer my truck would have a hard time reaching proper operating temps during the cold Canadian winters.
Hope this helps
Absolute
See this website for a better explaination
http://www.limboland.net/Merchant2/...2/merchant.mvc?Screen=PROD&Store_Code=pt&Product_Code=PZH101F&Category_Code=EBP
Ram Air is a little different, it has the opening at the front of the vehical where there is a high pressure area and grabs the high velocity air which helps to push air into the air box just before the filter. This helps to reduce the pressure differential across the filter and therefore reducing the effort that the engine must use to drawn air into itself.
I was thinking of installing a cowl hood on my truck but since I never see temps above 100'C or 212'F during the summer my truck would have a hard time reaching proper operating temps during the cold Canadian winters.
Hope this helps
Absolute
If you read up on that old theory about lift, flight, airplanes, wings, high pressure, low pressure, and air moving faster over the top of a wing you'll find out that it has been debunked. Why it is still taught to kids in HS I don't know.
Flight happens because of wing incidence.
Point being, the high pressure spot where the windsheild meets the hood is there because the air builds up against the change of incidence in the truck's shape at that point.
Flight happens because of wing incidence.
Point being, the high pressure spot where the windsheild meets the hood is there because the air builds up against the change of incidence in the truck's shape at that point.
For a cowl induction hood or a ram air hood to work you would need to seal it somewhat well to your aircleaner. And then your not really going to be force feeding your motor but more making sure it has plenty of nice cool air. I dont really see it feeding positive pressure to the turbo but it may give you a few ponies especially dependant on outside temps. JMO
Well to talk about selling parts I noticed that GTA runs a AFE intake and LTChip runs a K&N filter. Hey Ratlover I can't exactly remember but did you remove the filter completely once while on the dyno and noticed very little gain in performance.
I am always open to the fact that I am wrong (I have been trying to find the diffinitive source for good info on this) but This I do know, a cowl hood on a Dmax at best will only serve to get rid of A little heat and do nothing for performance.
Spicers famous report which was backed by many individual experiments by the members here have shown that the ad hype from K&N should be illegal, the filters do not add to the performance of the dmax and do not filter better then the stock filters. People with Afe intakes also have not been able to produce any solid numbers on dynos while using them. Many of the senior members here will state this. Naturally aspirated gassers do get benefit from intake kits but that is different technology.
Sorry to give misleading info but every one screws up now and then.
Later
Absolute
I am always open to the fact that I am wrong (I have been trying to find the diffinitive source for good info on this) but This I do know, a cowl hood on a Dmax at best will only serve to get rid of A little heat and do nothing for performance.
Spicers famous report which was backed by many individual experiments by the members here have shown that the ad hype from K&N should be illegal, the filters do not add to the performance of the dmax and do not filter better then the stock filters. People with Afe intakes also have not been able to produce any solid numbers on dynos while using them. Many of the senior members here will state this. Naturally aspirated gassers do get benefit from intake kits but that is different technology.
Sorry to give misleading info but every one screws up now and then.
Later
Absolute
Dynos are static stands that cannot replicate the conditions of on-road driving with regard to increasing airpressure to the intake be it from an induction hood, cowl, swiss cheesing the airbox or an AFE type deal. You have to take that into consideration and therefore dyno tests done statically are not to be used to debunk performance improvements of these systems.
Is there a way to measure performance improvements dynamically? How about track times? Anyone try controlled tests of track times with various intake systems on the same truck same conditions?
Is there a way to measure performance improvements dynamically? How about track times? Anyone try controlled tests of track times with various intake systems on the same truck same conditions?
I did pull out the factory paper filter and noticed no real difference on the dyno. It did a fine job of showing me there is no perf gain to be had with a drop in style filter in the factory housing.
IMO a cowl induction or ram air set up will only give you cool air(a good thing) and not really do any ramming into the motor. JMO. And for it to do that it would need to be reasonably sealed to the intake.
One could take a stock air box or a afe stage 2 and seal it up or make some ducting and acomplish the same thing. Sealing it against the back of the headlight and removing the pass side headlight at the track is a cheap/easy solution and what I would go after unless you want the :bling: of having a cowl induction.
A whole lota JMO
IMO a cowl induction or ram air set up will only give you cool air(a good thing) and not really do any ramming into the motor. JMO. And for it to do that it would need to be reasonably sealed to the intake.
One could take a stock air box or a afe stage 2 and seal it up or make some ducting and acomplish the same thing. Sealing it against the back of the headlight and removing the pass side headlight at the track is a cheap/easy solution and what I would go after unless you want the :bling: of having a cowl induction.
A whole lota JMO
ok, no one liked my riddle.
Answer: At 60, the air pressure at the base of the windshield is pos 0.9 inches water, enough to pressurize the cabin perceptibly when the vent is open. If there is an avenue to the motor (black seal removed for example), air goes in, not out.
To lend perspective to power: a 20 psi turbo creates 550 inches of water pressure, that's a 0.2% improvement to turbine output if you can capture .9" for intake. If in the process of ducting the new cold air source, you create 10" of head loss (easy to do), then you are going backwards.
Clearly the TD doesn't really benefit, except from cooler air supply.
Answer: At 60, the air pressure at the base of the windshield is pos 0.9 inches water, enough to pressurize the cabin perceptibly when the vent is open. If there is an avenue to the motor (black seal removed for example), air goes in, not out.
To lend perspective to power: a 20 psi turbo creates 550 inches of water pressure, that's a 0.2% improvement to turbine output if you can capture .9" for intake. If in the process of ducting the new cold air source, you create 10" of head loss (easy to do), then you are going backwards.
Clearly the TD doesn't really benefit, except from cooler air supply.
I never expected to get this many replies. I realize that it probly won't help with horsepower. I was just hoping to get hot air off my engine and MAYBE keep it cooler for towing and drag racing. I basically got it for looks just hoping for this other stuff. Keep posting and I'll keep learning. Thanks Kevin
I've been looking into a cowl for removing underhood heat as well. HERE'S AN IDEA!.....someone that hunts (with the wind in mind) and has some of that "white dust-in-a-bottle" could hang your wife out on the hood and squirt some across that cowl .....of course taking into consideration the wifes size and shape as she may affect airflow.):h ):h ):h .........seriously though . Ed.
.....of course taking into consideration the wifes size and shape as she may affect airflow.):h ):h ):h .........seriously though . Ed.since we have opened up this can of worms AGAIN, I have a problem I am working on.
Carhauler has an aftermarket cowl induction hood the dealer set him up with. They also cut vents in it at a know lo pressure area (mildly low, they should have located them further fwd, IMO) He says that the truck runs hotter when the cowl slots are taped over. He tows extreme weights and hi-drag loads.
makes no sense to me really, but if there is a high there, it dumps onto the turbo area.
Carhauler has an aftermarket cowl induction hood the dealer set him up with. They also cut vents in it at a know lo pressure area (mildly low, they should have located them further fwd, IMO) He says that the truck runs hotter when the cowl slots are taped over. He tows extreme weights and hi-drag loads.
makes no sense to me really, but if there is a high there, it dumps onto the turbo area.
The only way I could see that happening is if the underhood presure exceeds the pressure at the base of the windshield . . . which is not out of the question (I suppose) but I have no data to support that either way.
As far as the intakes go (not sure how we got on that topic) my AFE stg2 PG7 picked up a consistent 7hp and 19lb/ft at the wheels . . . with no assistance from forward motion . . . and besides that, it looks :bling: makes a cool whistling noise and I can afford it.
As far as the intakes go (not sure how we got on that topic) my AFE stg2 PG7 picked up a consistent 7hp and 19lb/ft at the wheels . . . with no assistance from forward motion . . . and besides that, it looks :bling: makes a cool whistling noise and I can afford it.
Well Ive been drinking again but I'll throw a few ideas out for play...
I was wondering if the high pressure area at the base of the windshield was relative to the front of the truck or to a sealed engine intake (nascar style) ?
In our dmax, is there a high pressure area when compared to the engine bay after the air is drawn in through by the fan?
To me these seem like two different situations.
I have just ordered a cowl induction hood and it will be installed monday. I wiil tie little pieces of wool to the cowl vent to see which way the air is being drawn at both idle sitting and at highway speed.
If nothing else it will give good info on heat reduction or potential for the members on this site to refer to.
Peace,
Absolute
P.s.
If non of this makes sense let me know cause like I said ... Drinking again!
I was wondering if the high pressure area at the base of the windshield was relative to the front of the truck or to a sealed engine intake (nascar style) ?
In our dmax, is there a high pressure area when compared to the engine bay after the air is drawn in through by the fan?
To me these seem like two different situations.
I have just ordered a cowl induction hood and it will be installed monday. I wiil tie little pieces of wool to the cowl vent to see which way the air is being drawn at both idle sitting and at highway speed.
If nothing else it will give good info on heat reduction or potential for the members on this site to refer to.
Peace,
Absolute
P.s.
If non of this makes sense let me know cause like I said ... Drinking again!
Well here I am Again and bin drinking a little but today I was driving around and these were my observations from the cowl hood install...
1) Engine runs a little cooler at highway speeds
2) When you let off the gas and cost down hill engine temps drop much faster then stock hood and they drop to a lower temp too.
3) If driving in ambient air less then 32'F or 0'C I would block the cowl induction off to maintain proper engine temps.
4) did not tie wool yet to truck hood to find if it draws air in or helps it to escape.... ?
Later
Absolute
1) Engine runs a little cooler at highway speeds
2) When you let off the gas and cost down hill engine temps drop much faster then stock hood and they drop to a lower temp too.
3) If driving in ambient air less then 32'F or 0'C I would block the cowl induction off to maintain proper engine temps.
4) did not tie wool yet to truck hood to find if it draws air in or helps it to escape.... ?
Later
Absolute
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