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Some thoughts and doubts about intercooling

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Rui
Do you really need that power at low speed? I'd be slightly scared at the prospect of using 200+ bhp cross-country! Or maybe you are into motorised bog-snorkelling?
My engineering experience has taught me that simplicity, and established solutions that are known to work, are always good; and that while trying new things is (usually) fun it is also (usually) expensive and difficult. Certainly if I were going to intercool mine, which I'd love to do, I'd pay Maarten in Holland a visit and get him to install his kit. He has done it before, knows what he is doing, and his solution is proven to work.
You are quite right that water will conduct away more heat, but isn't the simple and low-tech solution to that a water spray mounted on a conventional in-front-of-radiator air to air intercooler? I seem to recall that this is what rally cars use for short-term power boost. You could set that up for a few 10s of pounds or less.
As far as turbo lag goes, you would have to adjust the turbo anyway if you intercooled it, and the standard turbo setup on these vehicles is very conservative: for example mine doesn't really start to work until about 1800rpm. I very much doubt that a properly tuned setup would give worse turbo lag than you have at present.
The online pages on performance all suggest that a combination of large bore exhaust, intercooler, injection pump adjustment and turbo tweaks are the way to go if you want to boost performance. I *think* Maarten also offers the option of a different camshaft if you want still more power - you'd have to ask him.
The info I've read over the years suggests that you can raise the output of the 1HD-T to the 200 - 230bhp range without trying too hard. I've no doubt you could go beyond that, but you would have to start thinking about the other drivetrain components, and also the stress on the motor itself.
Sorry to be boring, but I really would go the "tried and tested" route with a FMIC, unless you are feeling very rich!
Christopher Bell (Typical "belt and braces" engineer)
Devon, UK
1HD-FT
|
|Hi all,
|
|I'm still interested in intercooling my 1-HDT 12
|valve. I already have a air/air core from a 15B engine
|(the same in Megacruiser) to be front mounted -
|although I haven't paid it yet. :))
|
|For our Cruisers, I see this issue in the following
|way.
|
|Our options:
|
|FMIC - Front mounted intercooler (air/air) - like
|Maarten, Safari and custom mounts like the one I'm
|thinking.
|
|TMIC - Top mounted intercooler (air/air) - lot's of
|4x4 use this, Subaru use this (except for WRC, where
|the factory cars change it to FMIC...). I think it's a
|poorer design since it will certainly be heat soaked
|in real world use.
|
|So, the FMIC will do the trick. But!... Certainly will
|be effective at high speeds and probably will increase
|turbo lag due to all the piping. In slower speeds,
|it's efficiency reduces drastically.
|
|Wich leaves me to the million dollar question: what
|about a TMIC air/water intercooler? Sure it's more
|expensive, more complex and more prone to failure
|mainly because the circuit has more components. But
|for the slow speed offroading, wouldn't it work best?
|
|Water keeps temperature 37 times better than air, from
|what I read. For a big rig like ours wouldn=B4t it be
|our best choice?
|
|Thanks
|
|Rui from Portugal
|
|1HDT
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Rui,
Yes an air/water will be more effective in terms of heat removal but you
have to consider what temperature of water you have available and what
temperature your air after the turbo will be, one from the other is your
delta T.
A lightly worked engine and turbo will not be providing much boost so the
air side will not need much cooling but you will have a cool bottom of the
radiator.
A hard working engine and turbo will be providing the air charge at a higher
temperature while the radiator will also be hotter ie when you need the
charge cooling most the delta T will be smallest, also when offroading the
air flow onto the rad will be limited.
At least if the application is bog-snorkelling the radiator could be
considered water/air? For that matter the front mounted IC would also be
water/air.
Malcolm Bagley
Stafford, UK
1975 FJ45 Pickup (In Work)
_______________________________
|Which leaves me to the million dollar question: what
|about a TMIC air/water intercooler? Sure it's more
|expensive, more complex and more prone to failure
|mainly because the circuit has more components. But
|for the slow speed offroading, wouldn't it work best?
|
|Water keeps temperature 37 times better than air, from
|what I read. For a big rig like ours wouldn=B4t it be
|our best choice?
|
|
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On 10/24/06, Rui Cruz <[Email address removed]> wrote:
Rui
You need power to do more work in a shorter time, i.e. go faster on a
motorway. For slow speed you need torque, for which an intercooler is
frankly of little use.
Because of that, an water cooled I/C will not improve your slow speed
offroading significantly, neither will an air cooled one, regardless
wjhere it sits.
---
Rgds,
Roman (London, UK)
'92 HDJ80
 
Hi Guys
So an IC be it water to air or air to air is only worth its weight in salt
if you are moving enough to generate air flow to cool the thing in the first
place is that correct.
If the vehicle is standing still or moving very slowly say in off roading
or traffic it will retain the heat for longer because of lack of air flow
around the engine and through the main rad and the IC rad is that correct.
The more power the engine generates the more heat is generated and so
unless you are moving a fair bit heat is hard to get rid of.
So if that is the case how do fairly staionary engines like on diggers
bulldozers etc keep cool enough.
cheers
john 92HDj 80 1HDT
 
Some diesels don't run much boost with the turbo and don't have an IC
Some use water/air and use a bigger engine fan
Some don't have a turbo
The generators I deal with at work are quite stationary and either have an
air/air IC or one of the above options. One of our engines is a V12, 27
litre displacement with 4 turbos, air/air IC and a 5ft diameter fan but only
rated at 720KW (little less than 1000hp).
Most diggers have relatively small engines with lots of gearing (often via
hydraulic drives). Peak or maximum power is not usually an issue; to get a
long life with continuous operation the engines are not highly rated. Torque
available is the important consideration.
Malcolm Bagley
Stafford, UK
1975 FJ45 Pickup (In Work)
_______________________________
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