[flash]

Back when I was still naturally aspirated, RS Barn suggested a Thermal Intake Gasket. I knew about these things already, and knew that there were successes with this sort of item on other cars, in terms of reducing intake heat transfer from the manifold to the head. Basically it acts as an insulator and transfers less heat. Seemed like a good idea, so when I decided to supercharge the engine, I bought one and installed it as directed.



Unfortunately, whether due to the material, or due to the loose tolerances in the holes, or both, the gasket did not hold up under boost. I developed a leak, which showed up as a small vacuum leak (about 2" of mercury), and caused a lean condition. Fortunately I caught this before I ran it lean and did any damage. Upon inspection, I found that the bolts didn't retain torque, and the gasket pattern from the manifold didn't quite match up right, leaving a very thin contact spot on the #4 cylinder.



Mine is not the only car to experience this problem. I now know of 2 others, and there may be more. One of them may have had the problem contribute to a detonation condition which blew a motor. (It is purely a theory at this time, and more investigation would need to be done to determine if that was the case)



Unless you have a vacuum gauge hooked up, or notice odd idle condition, or use an A/F meter and notice that things are lean, you won't see it until it's too late. It acts like it has a bit of an attitude, and doesn't happen all the time. For example, when my engine was cold, everything was fine. As soon as it got hot though, things lifted up and the leak showed up. I was able to repeat this condition in the garage using a pressurization contraption, and subsequently locate the leak.



These things may work fine naturally aspirated, but I have no data to say one way or the other. I'm pretty sure though that there are plenty of naturally aspirated cars running them without issue. You can probably contact them for that information.



At this time though, I must caution against using them in a supercharged application, at least until the problem can be identified and resolved. I have switched back to the OEM gasket, and I highly recommend that anyone running the supercharger do the same thing immediately. It would only take a matter of seconds of high RPM detonation to ruin a motor. The risk is too high, and without knowing what the problem is, and the knowledge that the benefits are minimal anyway, it's not worth it to find out the hard way.



Changing the gasket is a simple job, and can be done with the manifold still in the car. You only need to loosen the 2 bolts that hold the lower mount (about 3 turns), remove the dip stick retaining screw, lift up the fuel rail and hold it back, and then unbolt the manifold, lift it up, slip the gasket out, and then insert the new gasket. It took me a whopping 30 minutes yesterday to do the entire job.

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[vliegwielolaf1234]

Have a original gasket in there , never seen much use for a thermal one in a street car .

On the other hand i did install a SC <img src="/forum/images/smilies/968/wacko.png" class="smilie" alt="" />

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[flash]

lol - yeah - i only did it because i figured that any temp removed was a good thing. i didn't count on the expansion and gap thing that happens when things get hot. it may only be that the intake gets hotter now under boost, and the gasket can't keep up. not sure. i only know it leaked, and mine isn't the only one.



regardless, the leak is gone now with the OEM gasket.

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[Cloud9...68]

Anybody out there with one of these on an N/A car who has experienced any problems? I have one on my car, but I also have ceramic coated piston tops, combustion chambers, valve faces, exhaust ports, and exhaust manifolds, along with the D1R heat shield and a louvered hood, so hopefully my underhood temps will be pretty reasonable, even under track conditions. I think I will re-check the torque of the intake manifold bolts periodically.

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[flash]

i haven't heard of any N/A problems



15 lb/ft

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[Scott Collins]

I have one installed- two years and counting with no problems. Pretty sure it helps in the hot summer months here in Central New Jersey.

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[Cloud9...68]

[quote name='Scott Collins' timestamp='1365217788' post='141000']

I have one installed- two years and counting with no problems. Pretty sure it helps in the hot summer months here in Central New Jersey.

[/quote]

That's good to hear - when you say it helps, what do you mean? I got one simply because I was tearing my engine down anyway, and I figured that lowering the intake temperature by a few degrees couldn't hurt. Do you actually feel some sort of improvement relative to the standard gasket? Thanks.

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[flash]

it won't help at all with performance, but it can help with hot starts. the air is moving too fast through the manifold to make any change in intake temp. but it does act as an insulator and can help limit heat soak from the manifold, and help prevent boiling of the fuel in the injectors, both of which can happen when it's really hot and you shut the car down.

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[tamathumper]

And what is "really hot"? I'm pretty sure we don't have to worry about that in upstate New York.

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[Scott Collins]

When I installed it along with a top end engine redux, including a "Widefire" head gasket and new water pump, the idea was to reduce heat transfer from the cylinder head to the intake manifold. Sort of a preventative measure, but not something I expected to produce more torque or hp for racing through the neighborhoods of Central NJ. <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" /> The car had no issues with overheating and still does not.



I posted quite a bit on this job at the time, including my experience with the different water pumps available for our cars. I look for the thread last week when the water pump subject came up on the boards but could not find it.



Between mid-July and end of 'Aug we have temps from 85-100+ deg, usually with very high humidity.

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[flash]

engine bay temps, and everything in the engine bay, easily reach 200 degrees fahrenheit after running the car. when you shut it down, the temps climb quickly. the airflow through the engine bay, which removes that heat, is no longer there. things heat soak in less than a minute. that can cause problems in hot starting. the fuel can "boil" and make it more difficult. also, the temp sensors are all on the upper end of range, and consequently the DME tells the system to do things to compensate. these don't always match with starting. this is exactly why they don't want you to shut down your engine on a track, unless there is a risk of fire.



the thermal gasket is designed to help with this scenario. by insulating the intake manifold from the head, which is the heat source, it is designed to lessen the heat transfer, and thereby reduce the temps of the fuel in the injectors. this only applies to the heat soak scenario though. once again, things are moving too fast for this amount of heat to be a factor when things are running.



it will not increase power at all. the air is moving far too fast for any such device to have any measurable impact on temperature. the air is still going to enter the head at whatever temp it is picked up at. the heat of the manifold will also not change the intake temp enough to make any difference in power. it's all about the temp of the air at the inlet.



unfortunately the plastic gasket does not respond to heat the same as the aluminum. when you raise the intake temps like you do in supercharging, and then add the pressure of the boost, it results in expansion which tends to loosen the bolts. this results in leaks. you could loctite the bolts, but i don't know that it will hold. i haven't investigated yet, but perhaps the bolts could be changed to studs, and then locking nuts could be used. otherwise, diligent re-torquing would be required. i used to have to do that on the race car all the time. most people do. on a street car this would be a pain in the butt.



again, i have yet to hear of a problem on a naturally aspirated car. i tend to think though that most people using it are doing so for track use, and they would be re-torquing all of these bolts before every event anyway, just like they would do with the exhaust, lugnuts, spark plugs, yada yada. consequently i don't know that anybody is going to have a problem. even if they did, the dangers are minimal. on a supercharged engine though, those dangers become far more of a problem, as any lean condition, especially under heat or load, can result in catastrophic failure.

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[Lear35A]

Not following the logic here. If the boost in the intake manifold causes a leak, it seems to me the pressure of the airflow into the head would be lower than anticipated. Consequently there would be too much fuel not too much air. That would lead to a rich condition, wouldn't it?



Y

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[flash]

at idle, not on boost, a vacuum leak introduces more air into the system, and unregulated air at that. this causes a lean condition.



on boost, the MAF gets involved, and the DME gets confused. due to the leak, it "thinks" the engine is working less than it is, based on the MAF and O2 sensor readings, and pulls back fuel. however, the revs and TPS still dictate the need for the fuel at the higher load. this results in a lean condition. if we had a MAP sensor, things might be different, as it would be responding to pressure, and not flow.

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[Lear35A]

I don't think detonation at idle is a concern.

The <acronym title='mass air flow'>MAF</acronym> is upstream of the "leak" under boost so it is telling the DME I've got this amount of air going into the cylinder. The injector delivers the amount of fuel necessary for that amount of air. Due to the leak, though, there is actually less air going into the cylinder. That says rich to me. Still don't see what I'm missing.

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[flash]

no, it isn't, but it alerted me to the problem.



the way the MAF works is pretty complicated. it senses the flow as a sum of the components both before and after it. you would be amazed at how touchy it is to things in the flow path, on both sides. it takes very little to confuse it. i just went through this extensively when tuning my car. made me bat**** crazy. even the internal curvature of the 3" elbow dramatically affected things, to the tune of a 20hp difference and a huge low end stability problem. this is also "upstream" of the MAF. the mixture is full lean off throttle with one elbow, and 10.9 off throttle with the other. same size diametrically. same length of pipe. but the profile differs slightly. it's enough though to change the flow characteristics.



the same thing happens with a boost leak. it changes the flow before the supercharger. it's a pressure differential issue. remember that boost is the result of flow and restriction. it is not merely a factor of rpm. change the flow characteristics, and you change the boost. for example, porting a head may make things flow better, but it will lower boost readings. anything you do to reduce restriction will lower boost readings, though it may make more power.



when the boost reading goes down, the MAF "thinks" the engine is working less, and reduces fuel because it thinks it doesn't need it. the load reading at the ECU is a combination of MAF reading, TPS, and O2 readings. it takes those and crunches numbers and then tells the timing and fuel systems what to do.



if that isn't enough of an explanation, you're either going to have to trust me on this, or try it yourself.



this stuff isn't nearly as simple as some might think it is, and it's nothing like naturally aspirated.

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[DaveN]

Simple +1 for me. I had an elusive idling problem after a track day. Never could pinpoint the issue until rebuild. Thermal gasket distorted and torque good to hell on the manifold bolts. Back to OEM on fresh engine.

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[Cloud9...68]

[quote name='DaveN' timestamp='1365400768' post='141104']

Simple +1 for me. I had an elusive idling problem after a track day. Never could pinpoint the issue until rebuild. Thermal gasket distorted and torque good to hell on the manifold bolts. Back to OEM on fresh engine.

[/quote]

Was this with the supercharger, or was it before you added the SC?

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[bombfactory]

Glad you were able to find the vacuum leak Flash - and doubly glad that I didn't break your car during the tuning session. It was only 3/4 throttle, honest!

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[DaveN]

Cloud, that was with the SC.

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