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Engine compartment temps and flow direction

goldNSX

NSX Prime Moderator
Joined
15 May 2004
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6,898
My CTSC is running pretty hot with the engine cover in place and I wonder if anybody every measured the air flow through the engine compartment. The fan had to go with the CTSC but I'm looking into a DIY-solution with a custom fan. And no, the engine cover stays in place. :)
Reason: when the pulley gets hot I get the belt slipping some times. The pulley gets hot you can't touch it with you hand longer than a fraction of a second.
 
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i'm interesting to see what fan/airflow solution you come up with.
One of the most promissing solution would be an air intake scoop for the right side as one exists for the left side to the air filter.

My provisional solution is showed in the pics. Even with that easy solution I can lower the temps by about 10 degrees C (18 F) at the pulley. As it's only pressing part of the air in the engine compartment.

I've asked SoS and Downforce so far but nobody has the time to do this mod. Anyone can do a set of 100 or so? :)
 

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I had my kit 2011, so it's the latest version of the 'fixed' tensioner.
 
Yes, GY gator...
It's definitly the pulley/belt getting too hot under spirited driving conditions.
 
One of the most promissing solution would be an air intake scoop for the right side as one exists for the left side to the air filter.

My provisional solution is showed in the pics. Even with that easy solution I can lower the temps by about 10 degrees C (18 F) at the pulley. As it's only pressing part of the air in the engine compartment.

I've asked SoS and Downforce so far but nobody has the time to do this mod. Anyone can do a set of 100 or so? :)


Nice solution! I was thinking about the exact same thing last week.
 
Nice solution! I was thinking about the exact same thing last week.
I was first. :tongue::D

Joke asside, why did you think about it?

If only we could find a group of customers how would buy this thing. It's very cheap to produce and only needs elementary input to make it perfect.
 
I was first. :tongue::D

Joke asside, why did you think about it?

If only we could find a group of customers how would buy this thing. It's very cheap to produce and only needs elementary input to make it perfect.


I am trying to find ways to make the car faster. And cooler engine compartment for the ITBs is one of them. I did take out my engine compartment fan as well.
 
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One of the most promissing solution would be an air intake scoop for the right side as one exists for the left side to the air filter.

My provisional solution is showed in the pics. Even with that easy solution I can lower the temps by about 10 degrees C (18 F) at the pulley. As it's only pressing part of the air in the engine compartment.

I've asked SoS and Downforce so far but nobody has the time to do this mod. Anyone can do a set of 100 or so? :)

Interesting! Following this thread.
 
SoS sells this Downforce engine hatch duct garnish which is slightly higher for addes cooling: http://www.scienceofspeed.com/produ...e_products/NSX/Downforce/engine_duct_garnish/
Unfortunately the moving air detatches in the low portion of the rear window so I'm not sure how much more cooling would benefit. Nice part though.

Did anybody install it and can tell us if the opening is bigger (more diameter?) than the one of the OEM piece to allow more air flow?

I still think that a scoop on the right side would be more efficient as is cooling part of the front of the engine too.
 
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I took some measurements today. My solution lowers temps at the pulley by about 9 F or 5 degrees C.
 
Gold NSX,
If you are serious about that piece I am getting a custom piece made by a very good welder. He is making it out of aluminum and will fit perfectly like the SOS/DF on the driver side.
 
I am going to drop the car off at the shop in a few weeks when the weather is nicer.

The factory engine bay fan is about 5-6 I am seeing if he can create something to utilize the whole space to get the maximum air into the engine compartment.
 
Gold NSX,
If you are serious about that piece I am getting a custom piece made by a very good welder. He is making it out of aluminum and will fit perfectly like the SOS/DF on the driver side.
Thanks for your offer. Let me know what price he's asking for.
 
Gents,

I love DIY projects as much as the next guy but the heat transfer coefficient of metal to air is very very low. Just imagine how long it takes a warm engine to cool down sitting outside. While this vent duct solution might be of some benefit in creating hp to a ITB setup it may not work as well as you think for a CTSC or standard OE style intake which already gets cold air from outside the driver side vent.

Yes, there may be some benefit by cooling the engine bay further but is it enough to really matter? I'll bet my money no. If you're trying to create more HP by cooling the air intake charge temps (or curtail heatsoak) spray water or install an aftercooler.

The hot CTSC casing is caused by heat being transferred upwards from the engine block itself. You'll have better luck isolating this heat transfer by using phenolic gaskets and removing the engine cover.

Now let's pretend you manage to get your CTSC casing ice cold. Heat is created by compressing the air. You'll still end up with pretty darn high charge temps which increases exponentially as boost increases. Having ice cold rotors and casing isn't going to be enough to cool the compressed air entering the engine at high velocity. Even the common aftercoolers have much more surface area if you lay out all the fins on the heat exchanger just to cool sufficiently.

The hot pulley is caused by friction. If you have a slipping belt it will aggravate the situation even more. The small belt used on the CTSC has to turn A LOT of torque on that supercharger. It's the achilles heel of superchargers; parasitic drag. This friction creates heat. It's not caused by radiant heat surrounding the pulley which can be cooled with an air duct.
 
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RYU, thanks for your input, I agree with on some of your arguments:

1. An aftercooler would help cooling compressed air down. More hp -> best solution and you do the engine a favor. We're looking into it next winter. It's up to $3000.

2. During my testdrives I measured the hottest areas of the compressor at the pulley and the bearings. The rest of the unit was considerably cooler. Yes, it's friction of the belt and bearings under load. My belt isn't slipping anymore, well during 100 miles yesterday, as I torqued it slightly more (and due to the lower engine compartment temps).

The belt is torqued at it's limit now. I once had it torqued to the amount that the supercharger bearing were making terrifiing noises. No thanks. :wink:

3. Even if I mount an aftercooler the belt, pulley and bearings get still hot (friction).

4. I'm not looking for more hp mainly and cooler intake temps. Only an aftercooler would help here. At the given hp-numbers I'm looking for consistent power and a slipping belt in spirited driving is annoying.

5. An intake scoop is $165 from Downforce. If they could do a similar thing for the right side at below $200, it would be very cost-effective compared to $3000 for an aftercooler, again to avoid a slipping belt and get more consistent power.

I'll do some pics of my temps reading as soon as it stopps raining. Thanks again, I like these (only found on prime) discussions where we look deeper into it. :)
 
I think the point Ryu is making is that regardless of what you do in the engine bay to cool the ambient air around the supercharger, the heat soaked blades inside the supercharger will still cause the new cool air to warm up. You did mention that you wanted to get cooler AITs (air intake temps), but the only way to do this is with alcohol/water injection or an after cooler. If you are looking for lower Engine Bay Temps, then a scoop might help a lot. I think the best approach would be to thermally coat the supercharger and the headers as well as getting a thick plastic gasket between the charger and the engine so the engine heat does not transfer to the charger as much. Just a thought.
 
Good points, syndicate.

You did mention that you wanted to get cooler AITs (air intake temps), but the only way to do this is with alcohol/water injection or an after cooler.
See my point no. 4 above. RYU's argument is correct but what does it help me to get cooler IAT if the belt is slipping due to the heat around the pulley? The slipping belt under hard driving is the first thing I want to attack. -> cooler engine bay temps. :)

I think the best approach would be to thermally coat the supercharger and the headers as well...
I've opened a different thread about that recently. I was told by a friend who investigated coating headers that it's not long-lasting. The best way to coat would be the inside of the headers. Coating the supercharger may have no positive effect. If the air gets hot the heat has to be transferred out of the supercharger. It's even more critical if you don't allow the engine to loose it's heat. The inside gets cooled down a bit be the fresh air. If you want to cool the supercharger down the best place is the pulley and the bearings as they play a big role in generating heat around the pulley (video/pics follow).

Again, if any vendor would be willing to do a minimal batch of scoops for less than $200 each it believe it would be sold fast. The production cost in China is very, very low. I know that parts get sold faster if you can say that they result 1-5 hp but some people just spend their money for preventative maintainance. The less heat you have in your engine bay the longer every single (expensive!) part within it lasts. :) So it's not only good for SC/Turbo cars. :wink:
 
Good points, syndicate.


See my point no. 4 above. RYU's argument is correct but what does it help me to get cooler IAT if the belt is slipping due to the heat around the pulley? The slipping belt under hard driving is the first thing I want to attack. -> cooler engine bay temps. :)


Yeah I totally missed that :redface:
 
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