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Under Bonnet Temperatures Causing Heat Soak

edizio

By edizio,
in Engines & Forced Induction

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edizio Enthusiast

edizio

Posted
Posted

Hi!

So my next DIY project is to stop using the standard air temp sensor, which I believe is actually a water temp sensor. I actually read on this forum that the GM sensor is a pretty good alternative with a resistor in parallel (using powerfc so can't modify resistor values) if you can plumb it into an area of the system that doesn't get so heat soaked. Thinking just after the intercooler which is actually cold piping even after driving for many miles; in comparison to the hot to touch air intake plenum. I'm planning to do this in the next few weeks, so I will post a walkthrough of this like I did with my AAC cleaning.

This should help the tuning process as currently, after driving 50miles/80km, I'm having to retune slightly because the AFR is getting a little leaner than I want. It's only 1AFR leaner, so sitting at around 15.7 instead of 14.7, but I'm quite picky. The reason for the heat is because I'm running a single GT4294R turbocharger that's non-ceramic with no turbo blanket/wrapping on the down pipe. The fuel lines and right hand side of the bay is heat wrapped well but this isn't really helping things with the air intake which does tend to get hot. This brings me to my next subject: -

What are the thoughts on wrapping and turbo blankets? I hear that wrapping can cause cracks but haven't really heard anything bad about the decent turbo blankets. DEi are supposedly good manufacturers of turbo blankets but quite expensive.

If anyone has any comments or suggestions on a type of turbo blanket, I'd be massively grateful!

vetter2769 Proficient

vetter2769

Posted
Posted

I've just started experimenting with turbo blankets and heat wrap, currently have my mates 33 dump/front pipe wrapped, with a $40 turbo blanket and it makes a big difference, he had the same problem, you just could not put your hand on the pipe leading over the engine into the plenum it was incredibly hot, also his strut tower (turbo side) and strut brace would heat up it was ridiculous, now that problem has almost gone away thanks to some cheap wrap and a cheap blanket.

No idea how long it will last but it appears to be good quality stuff, it has been on for only 1 decent drive, so can't report on longevity.

XGTRX Veteran

XGTRX

Posted
Posted

Your setup is all you need. The wrap and blanket will make a huge difference. No need to ceramic coat as the wrap and blanket is much more effective to reduce under bonnet temps especially if you wrap down to the cat. Ceramic coating just looks prettier.

Ben C34 Grand Master

Ben C34

Posted
Posted

has anybody tried bonnet spacers?

I haven't. But the problem is the back of the bonnet is tyoically a low pressure area, so if you raise it or add a vent at the back air will come in there. Which from a generally getting fresh air blowing around the place perspective is a good thing, but it will negatively impact the amount of air coming through the radiator and intercooler. How much? Don't know.

Whilst that will probably reduce the engine bay temp a bit, and seem better to the non scientific approach of touching the rocker covers or plenum, whether it actually aids cooling the engine is questionable and could actually make it worse, as the radiator

And intercooler might not work as well.

End of the day its pretty easy to chuck some spacers on and see how you go. I would be inclined to tape some string around the area to see which way the air is flowing. Or streamers, they look heaps cool on cars.

Blackkers Experienced

Blackkers

Posted
Posted

I used 15mm bonnet spacers and removed the rubber liner just in front of the windshield. This was an old boosted honda prelude I owned many years ago but it made a few degrees of difference to coolant temps on the track for sure

  • Like 1
R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Hi!

So my next DIY project is to stop using the standard air temp sensor, which I believe is actually a water temp sensor. I actually read on this forum that the GM sensor is a pretty good alternative with a resistor in parallel (using powerfc so can't modify resistor values) if you can plumb it into an area of the system that doesn't get so heat soaked. Thinking just after the intercooler which is actually cold piping even after driving for many miles; in comparison to the hot to touch air intake plenum.

That's not really heat soak from under bonnet temps. That's just because it's bolted to the head and adsorbing heat... If you want to alter that you need to use a phelonic gasket or whatever they are called to insulate it from the head and it'll be cool.

The factory sensor is also quite slow to react, but after 5-10mins you'll see the IT temp is not actually that much higher than ambient. In the half a second the air goes through the plenum I can't see it picking up 30 degrees or anything.

  • Like 1
Badgaz Experienced

Badgaz

Posted
Posted

I haven't. But the problem is the back of the bonnet is tyoically a low pressure area, so if you raise it or add a vent at the back air will come in there. Which from a generally getting fresh air blowing around the place perspective is a good thing, but it will negatively impact the amount of air coming through the radiator and intercooler. How much? Don't know.

Whilst that will probably reduce the engine bay temp a bit, and seem better to the non scientific approach of touching the rocker covers or plenum, whether it actually aids cooling the engine is questionable and could actually make it worse, as the radiator

And intercooler might not work as well.

End of the day its pretty easy to chuck some spacers on and see how you go. I would be inclined to tape some string around the area to see which way the air is flowing. Or streamers, they look heaps cool on cars.

i'll give it a try...i've bought some 10mm spacers and i also have a gktech cooling panel...its not very scientific as i really only watch water temp....but i usually pop the engine bay after a long drive and it will be interesting to see if everything is still as hot to touch (obviously not the really hot bits)

XGTRX Veteran

XGTRX

Posted
Posted

Also a front end undertray will create negative pressure near the sump which has proven very effect in engine bay temps and also reduce turbulence in the engine bay to increase cooling efficiency of the intercooler and radiator. There are a few tests done that back this up. I think autospeed saw up to 10 degree drop from memory.

  • 8 months later...
burn4005 Proficient

burn4005

Posted
Posted (edited)

It's a bit late but I thought I'd share an intake temp sensor I have found that fits in the stock position m12x1.5

It's long enough to stick out in the air stream and has an open element so reacts quickly.

531991_150.jpg

http://www.finjector.com/verkkokauppa/eng/intake_air_temp_sensor_long_25_mm_open_type_fast_element_for_turbo_engines_m12x1_5-p-531991-28/

Edited by burn4005
  • Like 1

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