Go Back  RX7Club.com - Mazda RX7 Forum > Tech and Performance > General Rotary Tech Support
Reload this Page >

Heat management, hope this is the right place for this

General Rotary Tech Support Use this forum for tech questions not specific to a certain model year

Heat management, hope this is the right place for this

Old 01-03-19, 12:25 PM
  #1  
Full Member
Thread Starter
 
Join Date: Oct 2017
Location: Georgia
Posts: 55
Likes: 0
Received 4 Likes on 4 Posts
Heat management, hope this is the right place for this

Ok, so some changes I plan on making make me wonder about heat. I see that generally, for the engine bay, there are three locations I see people mainly wrapping/shielding/coating. Remember, my experience and skill level are layman at best, Iím trying to learn as I go. Can someone help me out understanding heat management? Some of what I see seems like it would be a double edged sword!

So, I understand as I pull power out, things are getting hotter. Bigger radiator, check. Iíd like to keep my top mount intercooler as long as I can. So, heat levels in the bay affect this quite a bit it seems, hence looking into methods of further cooling things off.

Back to the shielding:

The header/downpipe shielding seems a no brainer.

Turbo wrap, keeps heat from radiating into bay? For how long really? And that heat has to go somewhere, Iím picturing it raising the charge air headed to the intercooler. So, eventually raising the intake temp of the forced air into the engine itself? Does it cook the oil? Extend the cool down time after a run?

Manifold shielding seems about the same as the turbo shielding to me. That heat has to pass through the motor eventually? Or gets to the point it canít help anymore and eventually is actually radiating heat into the bay?

Isnít heat the bane of the rotary? Is it worth the drop in engine bay temps if all that heat is in or has to pass through our motor? Would venting or ducting be a better choice? Is this something that I need not even be thinking about? At what HP does this sort of thing become truly needed or useful at all?

Thanks for your time,
John



Ok, so thatís a stupid amount of questions to expect answered, but hopefully my point is evident? Is it worth my while or needed?

I havenít mentioned my car or upgrades because Iím guessing I am not the only one who may want this information, hoping to see what others consider the threshold for need or usefulness.
JLS 89 T2 is offline  
Old 01-03-19, 01:02 PM
  #2  
38 years of 7's
iTrader: (1)
 
mikejokich's Avatar
 
Join Date: Jan 2012
Location: Alabama
Posts: 318
Received 46 Likes on 39 Posts
This thread may help answer some of your questions.
https://www.rx7club.com/3rd-generati...ement-1127373/
Mike
mikejokich is offline  
Old 01-06-19, 05:15 PM
  #3  
destroy, rebuild, repeat
iTrader: (1)
 
gxl90rx7's Avatar
 
Join Date: May 2004
Location: Charleston, SC
Posts: 2,958
Likes: 0
Received 1 Like on 1 Post
before doing any of that.. ducting to your coolers is more important. make sure no air can get around the radiator, i stuff foam between the radiator and chassis

as far as engine bay, im not a fan of wrapping things, it can cause too much heat to collect in the manifold or downpipe. I run a metal heat shield between the intake and the turbo/exhaust parts and let the natural airflow through the engine bay take the heat away without stressing the manifold or downpipe
gxl90rx7 is offline  
Old 01-07-19, 08:42 PM
  #4  
Full Member
Thread Starter
 
Join Date: Oct 2017
Location: Georgia
Posts: 55
Likes: 0
Received 4 Likes on 4 Posts
Thanks for the replies. And the link, a nice read, but some pretty specialized stuff you did there! No results from your testing though, it needs an update!
I plan on trying to fab up some sort of shielding for the intake so it draws cooler air than the engine compartment, once i have the new radiator in. I will do intake temp testing when i do. Even got one of those vented headlight covers even though i find them a little ricey, and suspect they are more form than function.

I think you both get what i am asking though, is it detrimental to my engine to use some of these wraps to cool the bay.
I'd like to find a diagram of the air flow paths in the engine bay of a stock set up verses a modified one. All i need is a wind tunnel, a clear hood and front clip and lots of string. Should be easy, right?
JLS 89 T2 is offline  
Old 01-08-19, 10:36 PM
  #5  
38 years of 7's
iTrader: (1)
 
mikejokich's Avatar
 
Join Date: Jan 2012
Location: Alabama
Posts: 318
Received 46 Likes on 39 Posts
I would definitely wrap or ceramic coat the downpipe. There are two main reasons it helps. First, the underhood temperature will improve. I first ceramic coated my downpipe on my FD back in 2004 before it was common. The temps improved, particularly in the FD. The second is for the turbo and turbo spool both in the T2 and the FD. The exhaust gases lose velocity as they cool. By keeping the gases hotter longer, the exhaust velocity stays high and thereby decreases back pressure and thereby improves spool up and can slightly increase overall boost if your setup allows it. As for colder intake air, every 10F decrease in intake temp will potentially increase horsepower by 1.8% in a forced air inducted car. Again, this is dependent on the ability to use and transfer this colder air into the engine. That is why on my current rebuild I went overboard on delivering the coldest air possible to the engine.

As for an update on the thermal management thread, I just in the last two weeks having been road testing and tuning. The early numbers are looking good. I will post an update soon. My intake air at the stock location fast acting AIT sensor was 24-26C with outside ambient air of 18-19C on early testing runs. Even after 45 minutes I was still only 30C. This again is on a twin sequential FD, so that air is going through the spooling primary turbo. My underhood temp on the same day was 100-105F after popping the hood right after finishing. I was vey happy with all of this.
Mike

Last edited by mikejokich; 01-08-19 at 10:38 PM. Reason: grammar
mikejokich is offline  
Old 01-17-19, 08:01 AM
  #6  
Viable fossil
iTrader: (14)
 
Sgtblue's Avatar
 
Join Date: Oct 2003
Location: Mid-west
Posts: 10,380
Received 177 Likes on 154 Posts
Originally Posted by JLS 89 T2 View Post
....
I plan on trying to fab up some sort of shielding for the intake so it draws cooler air than the engine compartment... , is it detrimental to my engine to use some of these wraps to cool the bay?
Not as familiar with the FC but having the intake source ambient air Is always preferable.

And no, using header wrap on the down pipe wonít hurt the engine. As mentioned there is a slight performance advantage, though itís probably not going to be noticeable. DEI wrap is available at any chain parts stores but I recommend also using their spray sealant/paint with it. Give the pipe a good scuffing, spray the sealant, wrap and the spray the wrap. I personally prefer a couple good stainless worm-gear clamps to hold the wrap in place rather than those one-use stainless zip-ties that DEI also sells.
If you ever have the occasion to remove the DP you can also have it heat-coated. A little pricier but looks nice.

Sgtblue is offline  
Old 01-19-19, 10:11 AM
  #7  
Armchair engineer
iTrader: (2)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: http://www.k2rd.com
Posts: 24,650
Likes: 0
Received 131 Likes on 117 Posts
wrapping the downpipe is a good idea as long as its stainless

it is also valid to wrap the cold side of things too, for instance on my P port the intake is right over the exhaust, and instead of wrapping the non stainless header, i wrapped the intake.

so if you want to insulate something from heat, its perfectly valid to put the insulation on the cold side instead of the hot side...
j9fd3s is offline  
Old 01-19-19, 12:07 PM
  #8  
Viable fossil
iTrader: (14)
 
Sgtblue's Avatar
 
Join Date: Oct 2003
Location: Mid-west
Posts: 10,380
Received 177 Likes on 154 Posts
Originally Posted by j9fd3s View Post
wrapping the downpipe is a good idea as long as its stainless....
Not IMO. That's why I suggested using the DEI sealant/paint in the event he had a mild steel DP. Adhesion is great and with the stuff it doesn't matter if the DP is stainless or not. Even a mild steel DP will out last two or three engines. Mines' been on a mild steel BONEZ for a dozen years or more. Using it over the wrap prolongs it's life and has the added benefit of keeping it from being itchy to work around. Not as pretty as jet-hot or a heat coating, but effective and you can use it without removing the DP.

Hi-Temp Silicone Coating Spray | Design Engineering, Inc.
Sgtblue is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Rixie7
New Member RX-7 Technical
8
03-24-17 07:07 PM
junito1
Race Car Tech
36
10-29-16 10:40 AM
Cat G
Introduce yourself
1
04-15-14 03:32 PM
Bigus Dickus
Rotary Car Performance
12
06-02-02 10:38 PM


Thread Tools
Search this Thread
Quick Reply: Heat management, hope this is the right place for this


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: