How badly does a intake manifold heatsoak on a 8 valve?
One word, TERRIBLE.
Now that I converted to MS, I can log a lot of things. I have a BMF intake, the air intake temperature sensor is located near the 4th runner, on the side of the plenum where the metal is thick. Both my exhaust manifold, and turbine housing are ceramic coated. The harder I accelerate, the cooler my air intake temperature. :lol::lol::lol: My intake air is coolest at the end of my run. :confused::confused::confused: My turbo seems to blow cold air to cool the intake manifold, not blowing hot air to warm everything up. :eyebrows::eyebrows::eyebrows:
Look for MAT, that's the MS word for intake air temperature.
http://www.thelostartof.net/tryingbe...7/heatsoak.jpg
http://www.thelostartof.net/tryingbe..._175720767.jpg
Re: How badly does a intake manifold heatsoak on a 8 valve?
Cool! ;)
(^^See what i did there?? )
What was your MAT at the start? And you finished at about 120-124°F? What was the ambient air temp that day?
Looks like that intercooler is doing pretty good job!
Re: How badly does a intake manifold heatsoak on a 8 valve?
On the Reliant with the big intercooler the air intake temp was actually below ambient at the end of a pass.
Re: How badly does a intake manifold heatsoak on a 8 valve?
Pretty crazy it starts at 200 and goes down so hard the whole time. With all the heat sheilding I was hoping to see better numbers from a set up such as yours.. Where are you putting your air filter?
Re: How badly does a intake manifold heatsoak on a 8 valve?
I remember a customer who wanted to wrap his intake with a layer of Al leaving 1/4" for coolant, so water cooled intake. lol
I told him that once the air starts moving, and you have a Good I/C with proper sized turbo for power output, the actual temp of the heated intake has minimal effect on the temp of the air passing through it.
Re: How badly does a intake manifold heatsoak on a 8 valve?
Quote:
Originally Posted by
mopar-tech
On the Reliant with the big intercooler the air intake temp was actually below ambient at the end of a pass.
Assuming an air-to-air intercooler, I'm pretty sure some thermodynamic laws would need to be broken for that to happen. Unless you were spraying nitrous at the time?
Re: How badly does a intake manifold heatsoak on a 8 valve?
Quote:
Originally Posted by
contraption22
Assuming an air-to-air intercooler, I'm pretty sure some thermodynamic laws would need to be broken for that to happen. Unless you were spraying nitrous at the time?
In theory, the thermodynamic laws do allow for this to occur. The process is called adiabatic expansion and I use this at work (I am a scientist) to cool molecules down to approx 10 Kelvin (-263C). The idea here is a pressurized gas(Boost) is allowed to expand and thus cools the gas. This could happen after the cooling fins in the end tank/IC hose or plenum.
To help understand, let's look at the opposite process called adiabatic compression that causes a gas to heat up under compression such as in your engine or your trusty air compressor. You run your air compressor and the heated air(caused by adiabatic compression) is cooled down by the big air tank (or long line etc), now that extra heat is now removed. This ambient temperature compressed air is now expanded by adiabatic expansion as it leaves your air blow nozzle and thus it must cool down. Place your hand in front of the nozzle and it will feel cool, you can use a thin glove to eliminate the effect of moisture on your skin.
This type of expansion and compression is the basis of refrigeration/heat pump (Carnot cycle).
Since the temperature drop is caused by expansion after cooling of the charge, we must be losing boost pressure. Of course, the pressure must drop from the IC to plenum for flow to occur.
I hope this helps.
How badly does a intake manifold heatsoak on a 8 valve?
I can imagine the pressure drop numbers that would be in an environment that could create such a condition would be pretty bad.
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Re: How badly does a intake manifold heatsoak on a 8 valve?
I imagine the heat soak issue is one of the reasons for the expansion of the use of plastic intake manifolds, as they don't absorb heat like a metal would. Other than not being able to easily modify, the plastic seems fantastic (pun intended)...
Mike
Re: How badly does a intake manifold heatsoak on a 8 valve?
Quote:
Originally Posted by
wheming
Cool! ;)
(^^See what i did there?? )
Cool! No pun intended. :eyebrows:
Quote:
Originally Posted by
wheming
What was your MAT at the start?
I did a few runs before and was idling to change tune, so MAT started at 196.8F, coolant temp was 201.4F at the start of this V35 log.
When I WOT (at the beginning of the screen shot of this graph), air intake temp was 163F.
Quote:
Originally Posted by
wheming
What was the ambient air temp that day?
Weather history says it was 84-73 degrees between 6pm - 12am that day. The log is dated 10:24pm, so closer to 73 degree than 84.
Quote:
Originally Posted by
wheming
Cool! ;)
And you finished at about 120-124°F?
Coolest intake air got was 122.6F, and the end of the run. 7 seconds after the run, intake air temperature was at 140F.
Re: How badly does a intake manifold heatsoak on a 8 valve?
Quote:
Originally Posted by
masterjr33
Where are you putting your air filter?
Where it fits, between the upper and lower intercooler pipings, in the space between the radiator and fuse box.
Re: How badly does a intake manifold heatsoak on a 8 valve?
Quote:
Originally Posted by
chromguy
In theory, the thermodynamic laws do allow for this to occur. The process is called adiabatic expansion and I use this at work (I am a scientist) to cool molecules down to approx 10 Kelvin (-263C). The idea here is a pressurized gas(Boost) is allowed to expand and thus cools the gas. This could happen after the cooling fins in the end tank/IC hose or plenum.
To help understand, let's look at the opposite process called adiabatic compression that causes a gas to heat up under compression such as in your engine or your trusty air compressor. You run your air compressor and the heated air(caused by adiabatic compression) is cooled down by the big air tank (or long line etc), now that extra heat is now removed. This ambient temperature compressed air is now expanded by adiabatic expansion as it leaves your air blow nozzle and thus it must cool down. Place your hand in front of the nozzle and it will feel cool, you can use a thin glove to eliminate the effect of moisture on your skin.
This type of expansion and compression is the basis of refrigeration/heat pump (Carnot cycle).
Since the temperature drop is caused by expansion after cooling of the charge, we must be losing boost pressure. Of course, the pressure must drop from the IC to plenum for flow to occur.
I hope this helps.
Thanks for that succinct explanation.
Do you suppose that post IC adiabatic expansion, induced by a longish pipe getting to the IM, might offset some of the lag caused by that longish pipe?
How badly does a intake manifold heatsoak on a 8 valve?
I think you’d need a really poor flowing intercooler to create the pressure drop necessary for adiabatic cooling to take place, or at least enough cooling to take place as to be measurable/beneficial.
At that point, the pre-intercooler backpressure and exhaust backpressure would more than negate any possible gains.
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Re: How badly does a intake manifold heatsoak on a 8 valve?
Attachment 61635
Quote:
Originally Posted by
contraption22
Assuming an air-to-air intercooler, I'm pretty sure some thermodynamic laws would need to be broken for that to happen. Unless you were spraying nitrous at the time?
Nope.
Compared the intake temp with the ambient temp and it was clearly a few degrees cooler. You could see the temp drop as the car progressed down the track. Possible there was some cooling from fuel being sprayed in at the throttle body but I don't recall if I was still doing it at that point when racing the car but the system was still there and on stand by.
It is a whole lot of intercooler, still got it too.
Re: How badly does a intake manifold heatsoak on a 8 valve?
I think the fuel evaporation explains it. I know the blow-thru carb guys do experience an intercooling effect from the evaporation taking place in the intake, just like water/alky injection.
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Re: How badly does a intake manifold heatsoak on a 8 valve?
It might be worth noting that the silicone hose "horn" that runs from down from the compressor to the intercooler in this pic likely has a slight adiabatic effect.
Back to question of heat soaked IM, with our 8V heads the IM and EM share a gasket, and that means a heat insulating spacer at the head has to be ablative, be able to withstand exhaust gasses.
A few years ago, I made a 3/8" phenolic spacer which divides the upper and lower half of a two piece IM. As indicated by laser thermometer it works; it isolates a lot of heat in the lower half. Won't help with Harry's BMF IM here.
Phenolic, depending on type can be high temp and even be somewhat ablative. I never did find an appropriate type, able to stand up to exhaust gas. So I was thinking of a steel insert/donut/o-ring to shield the ID of a very high temp rated phenolic at the point where the exhaust gasses pass through the phenolic spacer. Meanwhile the adjacent phenolic is insulating the lower IM runner from the head. Bolts/studs, however, remain a heat path problem.
All of this assumes that the heat soak emanates from the head . . we still have the adiabatic heating from the compressor.
Just now found this - https://patents.google.com/patent/US8367178B1/en
A ceramic/phenolic paste for aerospace heat shielding.
Re: How badly does a intake manifold heatsoak on a 8 valve?
I thought there was some sort of group buy for a phenolic spacer for the 2pc intake? You're right, it doesn't help the BMF though.
Sometimes its amazing with all the design compromises we can make the kind of power we do.
Re: How badly does a intake manifold heatsoak on a 8 valve?
All this discussion jogged a memory- I considered at one point a water cooled intake with its own pump and radiator. Decided it was not worth the trouble, but something to think about.
Re: How badly does a intake manifold heatsoak on a 8 valve?
Quote:
Originally Posted by
wheming
I thought there was some sort of group buy for a phenolic spacer for the 2pc intake? You're right, it doesn't help the BMF though.
Sometimes its amazing with all the design compromises we can make the kind of power we do.
I looked into it. found a place. found the material. god some quotes . noone seemed to want to be on board. they were going to be about 70-80$.
Re: How badly does a intake manifold heatsoak on a 8 valve?
Quote:
Originally Posted by
masterjr33
I looked into it. found a place. found the material. god some quotes . noone seemed to want to be on board. they were going to be about 70-80$.
I thought I was?! Lol. It's like any other time folks even vendors have tried doing things. Everyone is interested until they realize its not free! What's another 70 bucks into my setup....
