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Uprated Charge Cooler from Alunox

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Uprated Charge Cooler for Lotus Esprit Turbo from Alunox


The charge cooler was introduced to the Esprit for the SE model in 1989, mechanical changes over the Giugiaro 910S (HC) turbo 2.2-litre were comparatively confined, yet horsepower grew by 14 per cent and torque by 17 per cent. With the standard Lotus charge Cooler, the engine is capable of holding a transient 280bhp for periods of up to 30 seconds.

So by holding the temperature of the charge to as close to the ambient as possible, will result in a more dense fuel air charge. This will increase the volumetric efficiency creating more power and torque.


So we come on to the new uprated charge cooler from Alunox.




The core volume has been increased by 3 times. Now we have a greater cooling effect on the air and have a bigger bank of air to supply the plenum chamber.

The bigger the better and the Alunox Cooler is about as big as we can get into the available space, it’s mounted on two rubber mounting bolts with new brackets. The unit is has a curved inlet and outlet design to aid flow.

Installation is very easy with all the hose connections being in the same position as the original unit.


Larger diameter hose connections for the water feed is optional and can be specified when ordering.




I can only comment from the driving experience at the moment. Also I am only running with the standard pump and radiator. You can still feel better torque on boost which doesn’t drop as fast at as the revs climb.

After driving hard, the charge cooler feels cool to the touch when putting your hand on the top surface.

The unit works well with my other modifications and enhances the Alunox manifold further.

Alunox are also looking to produce a high quality aluminum front radiator to match the thermal dynamics of the charge cooler as part of a kit to enhance further.

If enough Esprit owners are interested we may be able to get a group buy 

organised to keep the price down..

At present the charge cooler for a one off is in the region of £825.00 + VAT and the

front rad to be costed out, This could come down to £650.00 for a group buy

of 20+.. 

Let me know if you are interested....






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Free flow exhaust system at a sensible price should be next, tuning the manifold then a larger charge cooler the only part left which is an unknown is the exhaust.

I know Leon may be working on one, single, two or four port, tuned maybe to give a good growel like the boxter S.

It's getting exciting..............

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Doesn't an increase in front rad provide more benefit than an increase in charge cooler core size?

Sure I read this somewhere, wasn't lotus related but someone had put in a lot of work into analysis of charge temperature.....

Chunky Lover

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The large chargecooler that i posted does fit under the engine cover of the SE and X180R...


Lotus did have a kit to turn the AC condenser into an extended chargecooler radiator on the Sport 300 and X180R , so I'm sure that would be a good idea for increased capacity!


Vulcan Grey 89SE


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Hi Jim, I've had to make a small cut to underside of the cover to allow it to sit down. However Alunox are looking to reduce the standoff pillars on charge cooler cover plate to give more clearance.

This may be taking things a bit far ,but going back to the colour ,I know dark colours dissipate heat well but they also absorb it better too, so the charge cooler should be polished as not to absorb the engine bay heat.



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On my S4s I got my rad rebuilt locally to a 3 cord type and with some repumbing work joined it to the AC rad to increase capacity as per S300.

Easly up grade and with the 3 cord rad even has more capacity than the s300. I have removed the AC compressor as I'm running an S3 type vacuum pump in its place to feed my Nissan Patrol brake servo. 

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Doesn't an increase in front rad provide more benefit than an increase in charge cooler core size?


In a word No..The two basically work in series, The larger cooler will supply the extra

induction cooling by means of greater capacity with longer dwell time. However depending

on your coolant flow volume, it will heat and diminish VE as the induction charge gets hotter.

The bigger more efficient radiator at the front can allow the charge cooler to maintain the lower

temperature longer...

If you are just doing short bursts of speed then the bigger charge cooler on its own will give major

benefits. cool much better and longer..used with an increased front radiator capacity it will sustain

the cooling efficiency even longer.. Maintaining VE and performance.

Just increasing the front rad size on its own will give a small benefit but only as far as the std charge

coolers performance will allow.

To take it a step further, increasing the coolant flow volume with larger pipe size and pump as part of

the overall system has been proved to sustain very low induction temps in tests... I believe Alunox do

offer this facility as an option at no extra cost for those interested. 

however the plumbing in the larger pipes can be a  bit testing..



the increase in volume will increase turbo lag, not sure it would be noticeable


This will all depend on your turbo and system. Lag is more from the exhaust flow and spool up time,

Those of you who have now moved to the the new Alunox manifold will have no lag now and fitting

the larger charge cooler should not effect this..

On my system we have found and proved that by increasing the volume of the induction after the

compressor is a performance asset...

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If I ever do another Esprit, I'd like to think seriously about inducting from the other side.

Draw from the same side as the turbo, reconfigure, or replaced of course, push the air off to an inter-cooler where the current air-filter is above the fuel tank, feed from the current induction inlet. Then straight into a reconfigured plenum (something to defuse it all a bit), but thinking about it loosely, it doesn't seem too loony.

Life is like a sewer, what you get out of it, depends on what you put into it. (Tom Leahrer)

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Can you chargecool a carb turbo? or is it only the fuel injected cars?

Amateurs built the Ark

Professionals built the Titanic

"I haven't ridden in cars pulled by cows before" "Bullocks, Mr.Belcher" "No, I haven't, honestly"

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This will all depend on your turbo and system. Lag is more from the exhaust flow and spool up time,


yep, just a caution:

keeping the turbo the same, increasing the volume of the exhaust valve-to-turbine or compressor-to-intake valve will increase lag, though it may be miniscule for minor changes.

the 2 volumes and the physics of the turbo need be balanced

the pressurization ramp will be delayed from an exhaust side vol increase or higher friction/high inertia turbine; more gradual curve from an intake side vol increase

a turbo can be obviously be tailored to compensate if needed

no way to tell if the vol from the 3x cooler will be significant change from my couch, but consider:

an air-to-air intercooler positioned at the radiator would create lag measured in seconds

Edited by ragingfool35



just because I don't CARE doesn't mean I don't UNDERDSTAND

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Hi Chris, Yes you can put the charge cooler the carb turbo model. I've just been looking at the layout from the turbo to the plenum chamber , the cooler would mount the same way as mine regarding the cooler intake from the turbo , but you would then need to connect from the cooler exit to your plenum.

You will also need a front radiator and plumbing for the water supply.


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  • 2 weeks later...

I will be attending Castle Combe with a Charge Cooler for sale and hopefully a manifold. If anybodys interested PM me .




One of the ALUNOX chargecoolers or OEM?

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