reducing under bonnet temps

A

ALaN

Member +
alright guys and gals, i'm currently trying to lower under bonnet temps and had a thought but i'm looking for others thoughts on it,
would it be a bad idea to fit a turbo blanket on the exhaust housing of a ct9 as it is so small and already struggles with the build up of heat or would it be ok?
Cheers
 
Franza1

Franza1

Supermoderator & Area Reps Manager
Well i have fitted one all ready but i havn't run the car with it on, i can;t see it making much of a detremental effect to it to be honest. it's the same as any other turbo it's going to transfer a bit of heat from exhaust side to compressor side naturally, but you could also look at it in a way that's it's not going to transfer as much radiant heat.
 
sx_turbo

sx_turbo

Lifer
my turbo has a blanket on it, and my mani is heat wrapped, but personally i dont think theres much difference.
 
GTti

GTti

Member +
Perhaps the first step is to actually find out your underbonnet temperatures. What makes you think there is a problem?

I think the only poor design aspect is the top mount intercooler that suffers from heat soak. Then again they had no where else to put it.
 
scot-ish

scot-ish

Member +
where your filter and intercooler is located is important for heat soak, and also if your seriously bothered, you could bridge the coolant to the inlet, try reducing the temp of the inlet after a bit of hard driving,

i heatwrapped my mani on the last car, made a bit off a difference like, but the mani on 106 is alot larger than the starlet
 
A

ALaN

Member +
i'm still running the standard top mount which is my problem but i can afford a front mount til i get paid at the end of the month but even so reducing radiant heat is always good as dropping 50 degrees gives some where in the region of a 5% increase in power on an n/a engine so i imagine it would be similar on a turbo if not more.my filter is relocated to the front and i've heat wrapped the mani and down pipe but the turbo is still bare so alot of heat is coming from there.i just wasnt sure what effect it would have on the turbo with all the heat being trapped in as i know the wastegate cracks with the amount of heat it usually has to deal with.
 
Franza1

Franza1

Supermoderator & Area Reps Manager
ALaN said:
i'm still running the standard top mount which is my problem but i can afford a front mount til i get paid at the end of the month but even so reducing radiant heat is always good as dropping 50 degrees gives some where in the region of a 5% increase in power on an n/a engine so i imagine it would be similar on a turbo if not more.my filter is relocated to the front and i've heat wrapped the mani and down pipe but the turbo is still bare so alot of heat is coming from there.i just wasnt sure what effect it would have on the turbo with all the heat being trapped in as i know the wastegate cracks with the amount of heat it usually has to deal with.
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well it's not necessarly the ammount of heat it has to deal with it that makes it crack it's the rappid heating and cooling cycles that causes that, in theory lagging the turbo will make it less prone to cracking as it will allow the turbo to cool down more gradually.
 
dac69er

dac69er

Super Moderator
my underbonnet seems to get pretty damn warm. i have a front mount. all my ic pipes are lagged and i get inlet temps of 38-40 degrees. surely there is something odd there?
 
munday

munday

Member +
dac69er said:
my underbonnet seems to get pretty damn warm. i have a front mount. all my ic pipes are lagged and i get inlet temps of 38-40 degrees. surely there is something odd there?
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I dont think those temps are too bad at all mate
 
dac69er

dac69er

Super Moderator
munday said:
I dont think those temps are too bad at all mate
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really? would have thought that 30 degrees would be more like it? really tempted to raise the rear of the bonnet to see if it will improve matters but i dont like how that looks!
 
M

mr2 rev3

Member +
dac69er said:
my underbonnet seems to get pretty damn warm. i have a front mount. all my ic pipes are lagged and i get inlet temps of 38-40 degrees. surely there is something odd there?
Click to expand...


i didn't think you was supposed to wrap your intercooler pipes???
 
munday

munday

Member +
dac69er said:
really? would have thought that 30 degrees would be more like it? really tempted to raise the rear of the bonnet to see if it will improve matters but i dont like how that looks!
Click to expand...

A quick calculation assuming you are running a bar and have an inlet temp of 20 decrees C and a compressor efficiency of 70% (typical of a good turbo)

Then you compressor outlet temps will be roughly 113 degrees C!

EDIT: And it also gives you an intercooler efficiency of 78%! Very good imo
 
Last edited:
sx_turbo

sx_turbo

Lifer
mr2 rev3 said:
i didn't think you was supposed to wrap your intercooler pipes???
Click to expand...

wrap the pipes in reflective heat lagging, (heat wrap with tin foil glued on it) and it works like a charm :)

when running my old hybrid @19psi i had inlet temps of 40 degrees, with an autobahn fmic
 
munday

munday

Member +
monka said:
how the hell did you work that out
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bucketep91 said:
just what i was thinking lol and why?
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Just some simple maths guys ;)

Why? Well why not? its great to know what the likely outlet temps are so that you can get an appropriately sized intercooler and also work out how well the IC is doing its job...Very handy calculations to do. Its also easy to work out air density changes so that you can theorize the max power difference between intercooled and non intercooled engines...Maths is cool :p

Edit: Ricky those are pretty good temps!

:drive:
 
scot-ish

scot-ish

Member +
munday said:
A quick calculation assuming you are running a bar and have an inlet temp of 20 decrees C and a compressor efficiency of 70% (typical of a good turbo)

Then you compressor outlet temps will be roughly 113 degrees C!

EDIT: And it also gives you an intercooler efficiency of 78%! Very good imo
Click to expand...


65% intercooler efficiency is it not ??

as his temp to the inlet manifold is 38-40 degrees C

correct me if im wrong tho
 
munday

munday

Member +
scot-ish said:
65% intercooler efficiency is it not ??

as his temp to the inlet manifold is 38-40 degrees C

correct me if im wrong tho
Click to expand...

Which method did you use mate?

I did....

Intercooler efficiency = Actual temp drop/ Maximum possible temp drop

Which is 113 (temp of air from turbo) - 40 (temp post ic)
-----------------------------------------------
113 - 20 (assumed ambient temp)

= 73
--
93

= 78%

(hope this comes out in the right format!)
 
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