How badly does a intake manifold heatsoak on a 8 valve?

[tryingbe]

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/dodge/omniproject/2017/heatsoak.jpg


http://www.thelostartof.net/tryingbe/dodge/omniproject/2017/microsquirt/enginebay/IMG_20170918_175720767.jpg

[wheming]

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!

[mopar-tech]

On the Reliant with the big intercooler the air intake temp was actually below ambient at the end of a pass.

[masterjr33]

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?

[Shadow]

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.

[contraption22]

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?

[chromguy]

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.

[contraption22]

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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[zin]

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

[tryingbe]

Cool! ;)
(^^See what i did there?? )


Cool! No pun intended. :eyebrows:



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.


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.



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.

[tryingbe]

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.

[johnl]

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?

[contraption22]

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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[mopar-tech]

61635


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.

[contraption22]

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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[johnl]

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.

[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.

[mopar-tech]

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.

[masterjr33]

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$.

[wheming]

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....

[chromguy]

Has anyone tried to coat the inside of the IM to reduce thermal transfer to the charge? Just an idea

[contraption22]

You have to wonder how much heat transfer actually takes place from the manifold to the charge air at high RPM.

[masterjr33]

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....

you and me both. 70$ is nothing. its a nice dinner out. no big deal.
HONESTLY . if you really want it. you can buy the material yourself for about 20-40$
i measured needing a 15x4 inch piece to cut up myself. 3/8ths inch thick.
The "holes" can be done with a drill press and hole saw/bit.
so can the mounting holes. wouldnt be too hard.
but i went from building a engine on free time for a long term swap.
to a "need to put it in to keep the car running"..
The place that was going to do it was going to use a special blend to withstand 450 intermittent heat, 300 continuous.
and then CNC it for me. I was going to need to order 100$ (70x100 =7,000)
I was trying to get a vendor to go in with me on 30-50 of them. but didnt happen at that price range.
you COULD use two smaller pieces and make 2 seperate
like this picture below.
https://scontent-ort2-1.xx.fbcdn.net/v/t31.0-8/22769826_1706282676050545_1342942943100636635_o.jp g?oh=7c5395a3691d5dc83753b6e083a4a874&oe=5AAB6851

I had my 2 piece lower ceramic coated in and out ( wasnt supposed to be coated inside)
http://www.turbododge.com/forums/attachments/engine-general-exhaust-induction/226986d1495675431-assembling-top-end-img_20170524_190110-1-.jpg

Seems more to trap heat in the aluminum. more than it does prevent heat from the turbo getting to it.
Also had the exhaust coated in and out. and a sheet of insulation between them bolted to the fuel rail bolts.
http://www.turbododge.com/forums/attachments/engine-general-exhaust-induction/227018d1495675431-assembling-top-end-img_20170524_190138-1-.jpg
the intake still gets very hot.


check out the stock below

https://www.google.com/shopping/product/13898295073955435985?q=3/8+phenolic+sheet&biw=1474&bih=774&sa=X&ved=0ahUKEwiP6ffnqozXAhXo5oMKHdSpASEQ8wII7wIwAg

https://www.ebay.com/i/202013315225?chn=ps&dispItem=1

https://www.ebay.com/i/252985617117?chn=ps&dispItem=1

[tryingbe]

You have to wonder how much heat transfer actually takes place from the manifold to the charge air at high RPM.

Wonder? I have logs that show faster the engine speed, the lower the intake air temperature. Doesn't that imply very little heat transfer take place between the HOT intake manifold and the CHILLED inter-cooled air?

[tryingbe]

Has anyone tried to coat the inside of the IM to reduce thermal transfer to the charge? Just an idea

Or just WOT when you want your intake air temperature to be lower....

The only heatsoak intake issue I have is hot restart, car wants to run super lean, but I can tune that out.

Honestly, heatsoak intake is not an issue for me while I am boosting as you can see, faster I go, cooler the intake air temperature gets.

When I am not boosting, do I really care how hot the air intake temperature is? Actually, I take that back, the hotter the intake air temperature while I am cruising the better, I can get better MPG!

[Shadow]

Wonder? I have logs that show faster the engine speed, the lower the intake air temperature. Doesn't that imply very little heat transfer take place between the HOT intake manifold and the CHILLED inter-cooled air?

Bingo! :thumb:

[johnl]

Wonder? I have logs that show faster the engine speed, the lower the intake air temperature. Doesn't that imply very little heat transfer take place between the HOT intake manifold and the CHILLED inter-cooled air?

Yep, a graphed curve will illustrate the diminishing returns that your logs show. Still, I wonder if an isolator, simple and cheap, at the head would offer a benefit at the base of the curve, if only in spool point? The plastic intake manifolds on new cars offer more than just a lower production cost, they also reduce heat transfer to charge air.

[GLHNSLHT2]

My 87 ShelbyZ underhood temps were always pretty hot on those 100+ degree days we get up here during the 1st week of august. When I made an upper plenum for my 2 piece I put a phenolic spacer under it. On those days you could get out and rest your hand on the plenum while you looked under the hood right after shutting the car off. Most of the time it was cool to the touch from the cold air coming out of the i/c.

There's a few of those plenums and phenolic spacers floating around the community. If you're going to do phenolic at home make sure you use plenty of water and a mask while cutting it. As a machinist I hate the crap. Destroys the coolant in the machine, but I guess it's better than me breathing it. I'm not sure how thick a spacer you'd have to go to be able to move the intake mounting holes enough to have meat in the head to hold raised stud locations so the runners line up off the top of my head.

[tryingbe]

I just realized something.

For maximum MPG, intake air temperature needs to be HOT when cruising.

For maximum power and less chance for knock, intake aor temperature needs to be cool when boosting.

It would seem I somehow unknowingly stumbled upon the best of both worlds for a street car?

For my last tank of E54, I got 27.56 mpg. :eyebrows:

[Dr. Johny Dodge]

one way to keep the intake and plenium cooler is to simply paint them black

- polished metal retains heat thus things like chrome oil pans are not so cool - no pun intended

have you leaned on your black valve cover and noted the bare aluminum fins are hot enough to almost brand the palm of your hand but the painted surface is only just nice and warm ?

painting the tanks on the intercooler should help too but not the fins as that would reduce the efficiency of the fins
painting the tanks should help move the heat from the tank material into the tubes to cool also

I don't think much of the heat in the intake is going to be from the head - simple airflow through the ports should help draw any heat away from the intake as might the water outlet at the front at the t stat
more so the heat radiates up from the turbo .. and I've seen my turbo get really hot after a hard pull
so much so that 1-2 min later the turbine housing and s/v housing are cherry red .. still , and probably were hot enough to see through moments before

I don't think heat soak of the intake is an issue or ever was much of one even with the old log motors but I do think it would be nice if the fuel rail , injectors and regulator weren't heat soaking along with the intake
I've thought a few times a small scoop under the crossmember and a small duct leading air up the firewall and out somewhere might help as you might be able to direct the air where you want it with a little thought.. maybe a couple of holes in the side of each strut tower ?
- some air movement management around the turbo might help the most

perhaps our next step forwards in intake manifolds should look to 3D printing a new plastic one
- if that were simply a modded two piece bottom we would be off to a good start
(though I'd imagine the knock sensor might need to be moved off the intake)

[contraption22]

I don't think heat soak of the intake is an issue or ever was much of one even with the old log motors but I do think it would be nice if the fuel rail , injectors and regulator weren't heat soaking along with the intake


I'd figure the fuel system would be even less susceptible as it constantly has cool fuel from the tank circulating through it.

[Dr. Johny Dodge]

not so much as the tank gets warmer the longer you drive - thus one of the reasons for a returnless system

[johnl]

https://www.amazon.com/HM-FC-Titanium-Blanket-Fastener/dp/B01A6F02TW?SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-d-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B01A6F02TW

$27 turbo wrap


As for ducting, isn't the base of the windshield a point of high pressure when moving? And, aren't there low pressure points under the car? So .. . duct pickup from the cowl directed down onto the hot side, swing valve, and downpipe?

[wheming]

Anyone that wants one of those, i have one! It didn't fit with my setup.

[johnl]

And then there's a corrugated stainless/ceramic/stainless sandwich.

http://www.thermalcontrolproducts.com/index.php/our-products/industrial-heat/stainless-steel-heat-shields/

[tryingbe]

https://www.amazon.com/HM-FC-Titanium-Blanket-Fastener/dp/B01A6F02TW?SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-d-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B01A6F02TW

$27 turbo wrap


You must not have BMF intake manifold.

http://www.thelostartof.net/tryingbe/dodge/omniproject/2015build/intake_exhaust/pic053.jpg
http://www.thelostartof.net/tryingbe/dodge/omniproject/2015build/intake_exhaust/pic054.jpg
http://www.thelostartof.net/tryingbe/dodge/omniproject/2015build/intake_exhaust/pic057.jpg
http://www.thelostartof.net/tryingbe/dodge/omniproject/2015build/intake_exhaust/pic061.jpg
http://www.thelostartof.net/tryingbe/dodge/omniproject/2015build/intake_exhaust/pic062.jpg
http://www.thelostartof.net/tryingbe/dodge/omniproject/2015build/intake_exhaust/pic063.jpg
http://www.thelostartof.net/tryingbe/dodge/omniproject/2015build/intake_exhaust/pic064.jpg
http://www.thelostartof.net/tryingbe/dodge/omniproject/2015build/intake_exhaust/pic072.jpg

[Dr. Johny Dodge]

And then there's a corrugated stainless/ceramic/stainless sandwich.

http://www.thermalcontrolproducts.co...-heat-shields/ (http://www.thermalcontrolproducts.com/index.php/our-products/industrial-heat/stainless-steel-heat-shields/)

THAT could be a winner ^

especially for the log motor guys that almost all need something to replace the old o-e heat shield under the fuel rail

I made a shield for my log motor long ago from a piece of mirror plate stainless - it had been cut to fit flat in a dart/duster cluster to mount custom gauges but had never been cut for the gauges it made the perfect shaped and sized heat shield for my log motor
I simply added two L shaped brackets that I riveted to it so I could bolt it to the manifold at the stock heat shield mount points
then I drilled the fuel rail where the clips hold the o-e shield to the rail , drilled the piece of stainless to match and put two screws in to hold it all together

two pieces of stainless like mine with something to sandwich in between would be really cool

[Dr. Johny Dodge]

something to keep in mind is the idea of a shield that cannot soak up gas if you have a fuel leak
- but something that can keep the fuel from dripping directly on the exhaust also is good to consider
on my log motor , the first time I drove it I had am O ring on the injector leak (no heat shield)
every time the injector fired it shot a little stream of gas directly at the swing valve housing where it instantly vaporized
one of those "I'm glad I caught that deals" lol

[masterjr33]

And then there's a corrugated stainless/ceramic/stainless sandwich.

http://www.thermalcontrolproducts.com/index.php/our-products/industrial-heat/stainless-steel-heat-shields/

you can get tons of that at the junkyard. just look under newer cars.. even the the focuses have that.
almost all BMW do. even older. jags and lexus.

You could get a 5 foot by 3 foot piece in a 10 minute trip.

[tryingbe]

Relocated the MAT sensor to right after the intercooler. Temp is much more stable.

http://www.thelostartof.net/tryingbe/dodge/omniproject/2019/mat/mat1.jpg

http://www.thelostartof.net/tryingbe/dodge/omniproject/2019/mat/mat2.jpg

[chromguy]

Makes sense

[minigts]

Is this a good idea to move the sensor here? What is the advantage, other than knowing your temp values are going to be lower. Genuinely curious as to the validity of this and why it wasn't or isn't done more often.

[tryingbe]

Is this a good idea to move the sensor here? What is the advantage, other than knowing your temp values are going to be lower. Genuinely curious as to the validity of this and why it wasn't or isn't done more often.

It makes my hot start a lot easier.

[minigts]

This is good info! Wondering if somewhere I have an issue with my air charge temp sensor since I have this issue now. I have tried just about everything swapping out all kinds of spare parts with no change. My next option is to retime the car with the stock cam gear from the adjustable on it now.

[contraption22]

This is good info! Wondering if somewhere I have an issue with my air charge temp sensor since I have this issue now. I have tried just about everything swapping out all kinds of spare parts with no change. My next option is to retime the car with the stock cam gear from the adjustable on it now.

Isn't your issue cold start as well?

[thedon809]

Most cars nowadays put the intake temp sensor in the intake tube before the throttle body.
https://drive.google.com/uc?export=download&id=1QYWZ3CCJPBBn1j-RLavg0K-aQUQNB27x
My eagle hemi 5 speed swapped 2002 ram 1500.
https://drive.google.com/uc?export=download&id=1QYkIqw58LGCjAhVS4HhM4tM0NiChDfI1

[minigts]

Isn't your issue cold start as well?

It can happen, but after the car sits overnight it will start right up.

[chromguy]

My CSX is cranky when hot but fires up if I open the throttle a bit. I was thinking on running a test as I have a MPFlash installed. I will hot start with a T1 tune to see if that solves the issue.

[minigts]

My CSX is cranky when hot but fires up if I open the throttle a bit. I was thinking on running a test as I have a MPFlash installed. I will hot start with a T1 tune to see if that solves the issue.

Mine does it when hot and no amount of throttle helps. Has to be either timing, wiring or a bad new sensor for my issue.