[sagarpadaki]

Wouldn't a steel bottle be better off than a thermos flask? I understand that steel absorbs heat from engine bay and inturn heats up the coolant . But on the flip side, the thermos maintains the 36 odd degree of temperature for a few hours atleast. I am sure you must have given this a thought and decided on the thermos. .

[suhaas307]

Originally Posted by Dr.Naren

It's really a great work. I have seen many tuners struggle to make good power with 1.2 TSI, thanks to super high IAT. This hack / engineering is working really well, thanks for all the hard data like IAT, Coolant temperature etc. I believe only thing to take care of is not to switch off the engine immediately after hard driving

Agreed!

But we have scheduled another logging session soon. Let's hope it works out!

Originally Posted by Dr.Naren

Suhaas, I have a doubt if Frank Mehta's Coolant cooler was actually a divorced circuit.

https://www.team-bhp.com/forum/modif...my-gt-tsi.html (Upping the Cool quotient: Add-on Coolant Cooling system on my GT TSI!)

Could very well be!

Originally Posted by sagarpadaki

Wouldn't a steel bottle be better off than a thermos flask? I understand that steel absorbs heat from engine bay and inturn heats up the coolant . But on the flip side, the thermos maintains the 36 odd degree of temperature for a few hours atleast. I am sure you must have given this a thought and decided on the thermos. .

The thermos flask is essentially a steel bottle!

Actually, I must clarify that the thermos flask has pretty much lost its efficacy, much to my disappointment!

Reason: The bottom few inches of the flask comprise of several (sealed) layers that lend such thermos-flasks their ability to insulate their contents.

However, we have bored a hole in the bottom of this bottle, right through all the layers, essentially reducing the bottle's effectiveness as a thermos flask to nought.

And before anyone jumps at this, I must also clarify that we are aware the steel bottle will heat up its contents a little more than a plastic reservoir would. We want to log the car again and see if we need a solution for this. There are a couple of options we are open to considering based on the log results.

[Mortis]

You could use maybe something like the zalman reserator as a coolant bottle. It has a 2.5L capacity and already fitted with nipples for coolant to flow in and out. Probably won't be able to handle the flow rate though. You could also strap a CPU fan to a copper bottle also.

[sandeepmohan]

Originally Posted by suhaas307

The engineers at Volkswagen are not stupid. They knew exactly what they were doing when they engineered this motor. They may have left something on the table for the enthusiasts, but the real reason for this compromised system is – cost!

I will not call this a compromised system at all. In my view, this is a brilliant system versus the standard IC system that relies on ambient air to cool down the charge. This car (or any car) was not designed to be driven WOT, all the time. There are purpose built cars for that. The occasional flooring of the right pedal will give you access to most of the power the engine can produced. For 99% of driving conditions, this system will do a better job than a air cooled IC. It should cost more to build and engineer this system versus an air only IC based system. That said, it is a one time R&D effort and cost after which you have a system that can work with a range of turbo charged engines.

The iconic 2004 Subaru Impreza WRX STI also used a water cooled IC but not anywhere as complicated as what VW have done. You basically hit a button on your dashboard that would spray the IC with water :-). The reservoir tank was located in the boot.

Wish I had taken the effort to sort out this heat soaking problem I had on my 2011 Linea T Jet. As I discovered much later and on reading others experiences on our forum, the stock IC was useless. I never understood what this was. All I knew was the engine felt starved of air on a hot day and it killed performance. Felt like the car had lost all its power.

Thanks for sharing. That is a lot of well thought out work being done on your car.

[venkyhere]

Originally Posted by suhaas307

And before anyone jumps at this, I must also clarify that we are aware the steel bottle will heat up its contents a little more than a plastic reservoir would. We want to log the car again and see if we need a solution for this. There are a couple of options we are open to considering based on the log results.

IMHO, 'material of the container' hardly matters, when you have a dedicated heat-exchanger in the front grille, to dispose off the heat. I would rather suggest you stick to the steel bottle, atleast it is robust and leak free, without needing much space, plus having a nice 'neck' to help with mounting. In my books, this is better than placing a bulbous plastic thing in the location where you have put this up. If the seals of the inlet/outlet hold good for this current thing, leave it be.

[ImmortalZ]

Originally Posted by Mortis

You could use maybe something like the zalman reserator as a coolant bottle. It has a 2.5L capacity and already fitted with nipples for coolant to flow in and out. Probably won't be able to handle the flow rate though. You could also strap a CPU fan to a copper bottle also.

The fan would draw hot ambient air and blast it onto the copper bottle. Which would help...how? And compared to the radiator fan's 1000+ CFM, what would a piddly CPU fan do anyway?

Originally Posted by sandeepmohan

I will not call this a compromised system at all. In my view, this is a brilliant system versus the standard IC system that relies on ambient air to cool down the charge. This car (or any car) was not designed to be driven WOT, all the time. There are purpose built cars for that. The occasional flooring of the right pedal will give you access to most of the power the engine can produced. For 99% of driving conditions, this system will do a better job than a air cooled IC. It should cost more to build and engineer this system versus an air only IC based system. That said, it is a one time R&D effort and cost after which you have a system that can work with a range of turbo charged engines.

The iconic 2004 Subaru Impreza WRX STI also used a water cooled IC but not anywhere as complicated as what VW have done. You basically hit a button on your dashboard that would spray the IC with water :-). The reservoir tank was located in the boot.

Wish I had taken the effort to sort out this heat soaking problem I had on my 2011 Linea T Jet. As I discovered much later and on reading others experiences on our forum, the stock IC was useless. I never understood what this was. All I knew was the engine felt starved of air on a hot day and it killed performance. Felt like the car had lost all its power.

Thanks for sharing. That is a lot of well thought out work being done on your car.

I think you've missed the point entirely. It is not a new revelation that this is an air to water system (well, most of it anyway). An air to water system is superior to air to air systems in terms of performance. It is the complexity and maintenance requirements that make it unattractive. However, there are now several modern cars, performance oriented or otherwise, which run air to water charge cooling systems. The B4 S4 and any other model and variant which have the 3L supercharged V6, the new 2.9 turbo V6, any modern BMW M product, any BMW product with the 4.4L V8... the list goes on. Hell, BMW went as far as adding water injection to the M4 CS.

And I do not agree that a car is not designed to run on WOT all the time. Any car worth their salt will be tested in extremes. Engines are tested by running them at WOT for hours on end. Cooling and oiling systems will be designed for that. Cars are compromised in terms of performance so that even the most hamfisted driver will not kill it as long as they confirm to the service intervals. At least, that's how things used to be before modern emissions regulations. Now with emissions regulations being what they are, engines with particulate filters will pretty much hit limp mode very very quickly when used in extremes.

In any case, we're looking at an engine design from the 80s repurposed to hit displacement related tax rebates. And evidently, every penny that can be pinched, has been pinched. Why else would they do this to save a few clips and a coolant reservoir? There is no explanation. The design is severely compromised by sending 85degC coolant into the W2A core.

Comparing an IC spray to a full water to air system is like comparing the effectiveness of a fire engine to pissing on the fire. It is not a "water cooled" intercooler in any sense of those words. It's a push button overboost that works for short periods of time.

[rageshgr]

Originally Posted by suhaas307

Hi Venky,
...

Awesome mod Suhaas. The double divorced one. But one wondering I have is:
1. Now turbo shares the loop with engine . So doesn't that make the turbo run hotter than before because the coolant is now shared with engine as well?

[sandeepmohan]

Originally Posted by ImmortalZ

An air to water system is superior to air to air systems in terms of performance. It is the complexity and maintenance requirements that make it unattractive.

I don't remember saying the air to water system was a ineffective or a new approach. Am well aware that it has been around for well over a decade. I said it was better to an air to air system.

You have to remember that nobody ever lifts the hood on their cars these days. Heck; I've seen folks run their cars for 2 years without an oil change. To introduce more check points on a car isn't ideal. It is different compared to us folks trying to extract more out of the engine.

Originally Posted by ImmortalZ

And I do not agree that a car is not designed to run on WOT all the time.

I stand by what I said. The cooling and lubrication systems on a VW Polo GT Tsi isn't anywhere remotely close to what is engineered for, say an Audi S5. They are two very different cars.

Originally Posted by ImmortalZ

The design is severely compromised by sending 85degC coolant into the W2A core.

Agreed and a question that needs to go to the engineers at VW on why they chose this approach. There will be reason but I doubt if that reason was to save a few dollars, considering they already spend a lot in designing and building a complex air to water system.

VW could have picked a better place for the charge air cooler but that will require longer plumbing which you probably don't want. We don't know the reason for the existing layout.

Originally Posted by ImmortalZ

Comparing an IC spray to a full water to air system is like comparing the effectiveness of a fire engine to pissing on the fire.

I was not comparing the two systems. I was just highlighting another solution that was tried by another manufacturer a long time ago.

[suhaas307]

Update:

My little Polo is inching closer to the 40,000 km landmark, and if it wasn’t for the lockdown, I would have easily breached the landmark before July.

The changes made to the car, specifically the downpipe and the divorced coolant circuit, have transformed it, and the driving experience it delivers is nearly flawless.

I say nearly, because fiddling with the coolant lines has resulted in a slight vibration that can be felt through the pedals. Diagnosing the problem has revealed that the coolant lines are now vibrating against certain components only when the car is stationary and idling, consequently causing the rattle. Personally, it does not bother me too much and I am relieved that it’s not a serious issue. Venkat has nonetheless promised to rectify it.

Venkat has also been exploring options that could, potentially, further improve upon the divorced coolant circuit mod. He had something of a eureka moment in June, and immediately swung into action.

The idea: Incorporate an additional radiator – in series - along with the existing one that services the charged-coolant line.

Adding an additional radiator in series with the exiting one would not only increase the surface area for improved cooling of the errmm.. coolant () flowing through them, it would also expand the capacity of the coolant for the charged air. The goal is to further reduce the IATs, if possible.

It was decided that a new radiator will be used, identical to the secondary radiator, to achieve this.

Venkat pulled a few strings and managed to source the secondary radiator over the counter, and after picking up the part, I headed straight to his workshop to get it fitted. The cost of the new radiator was around 13k.



Parallelly, Akshay from GT Tunerz sent across a Borla ProXS muffler as I was looking to address the exhaust note with an aftermarket end-can. I found the Borla muffler to be reasonable, and based on feedback from others, I as told that it’s designed to be on the quieter side.



I arrived at Blackworks nice and early, and Venkat immediately removed the front bumper and inspected all possible mounting points, brackets, room available for the additional radiator, etc. The plan was to initially mount the new radiator above the existing secondary-one, but space constraints forced him to explore other options. After carefully studying the bumper and the frame behind it, he concluded that the best option was to mount the new radiator in front of the old one, as the bumper had sufficient room to accommodate it.

We also realized that mounting the radiator did not require a lot of work as the unit is quite light to begin with and will not need heavy-duty mounting points or brackets. Even though the necessary brackets were prepared, we did not use them.

So, how was this executed? Here are the highlights:
1) The front bumper was removed, the area was inspected, and it was settled that the new radiator can be mounted in front of the existing one.
2) Venkat used rubber hoses, similar to the ones used for the coolant lines, to run the new radiator in series with the secondary one. Initially, we were looking at getting a custom U-shape silicone hose but finding one on short notice proved to be impossible. We found the rubber hoses lying around the workshop that did the job just as well.
3) Since the new radiator was is super light, we did away with the heavy-duty brackets for mounting and utilized the frame behind the front bumper (that houses the primary and secondary radiators) to mount the additional radiator onto it.

Installing the additional radiator did not take more than a couple of hours.

First, the front bumper was removed, and the location for the new radiator was finalized:




Once positioned and marked, the plastic frame that houses the primary and secondary radiator was trimmed to accommodate the additional plumbing.




The other end of the radiator with the dummy plastic housing also required a little trimming to accommodate it in the space available behind the front bumper.



The bumper too required a little trimming to ensure that the new radiator does not foul with the bumper (notice the small bits of bumper on the floor)



The stock radiator hoses:


The re-routed plumbing now consists of one additional U-shaped rubber hose that connects the exit point of the original radiator to the entry point into the new radiator.



Photograph of the new radiator mounted in series with the secondary radiator and positioned in front of the secondary radiator:



After the installation, we took the car for a spin, hooked up VCDS to the OBD and noticed something extremely unusual after about 15 minutes into the drive: The IATS had shot up to 85 degrees! We pulled over to the side of the road immediately, inspected the plumbing (which appeared to be fine) opened the secondary reservoir and noticed that the coolant level had not dropped at all and in fact, the coolant was cold – a clear indication that the coolant is not doing its job of absorbing heat from the charged air.

Unfortunately, we had wrapped up at the workshop as it had gotten late, and I decided to drive home gingerly to avoid causing any damage. The plan was to drive again to the workshop in two days to diagnose the issue.

Two days later, upon a detailed inspection at the workshop, we realized that the coolant from the secondary reservoir is now being circulated through the lines – something that was not happening after the install two days earlier. We attributed this to an air-bubble somewhere in the circuit that caused the circuit to be blocked. Perhaps the drive back home that night had shaken the circuit a little causing the circuit to burp the air out and allowing the coolant to finally circulate through the lines. After the drive back home, I also noticed that the coolant level in the secondary reservoir had dropped quite a bit and I topped it up with water – about 700 ml to be precise.

The results:

On the day when I had gone back to Blackworks to diagnose the issue, Venkat hooked up the VCDS to the OBD and a few hard runs revealed that the IATs has dropped by a few degrees to around 40 degrees. WOT runs resulted in a temperature spike to around 50 degrees. At first it seemed like the slight drop in IAT was marginal and that there was no real benefit of the additional radiator, but Venkat then noticed that immediately after the WOT run, the IAT which had creeped up to 50 would now fall to the early 40s in a matter of 3 seconds. Before the installation of the additional radiator, any spike in IATs would take at least 30 seconds to about a minute to fall back to acceptable levels.

So, although this modification has not resulted in a huge drop in IATs, it has resulted in:
a. Recovery rate of IATs after WOT runs has improved drastically. In essence, the IATs now take just a few seconds to recover after wide-open-throttle runs instead of taking 30 seconds to recover. This effectively ensures that the engine can now deal with sustained flogging without having any impact on performance at all.
b. The divorced circuit and secondary reservoir can now hold a much larger volume of coolant-water mixture since the new radiator has expanded the volume of the circuit.

In the real world, the car now pulls quite strongly in the mid-range and it feels like some additional horses have been unleashed. In fact, during one particular pull on an empty stretch in the city, I was surprised by just how incredibly punchy the engine felt in the midrange that I cannot wait for a revised Quantum map to exploit the potential unlocked by Blackworks and the revised coolant setup. The timing of this modification, with the impending monsoon season, couldn't have been better. Now that the IATs are in check and the new radiator has been installed, and with Bangalore ambient temps hovering in the mid-20s, the car feels like it's running on steroids!

A note on the Borla ProXS muffler:

Venkat swapped the stock muffler for the Borla unit, and I have to say, it’s not as impressive as I thought it would be. There is just bass now, a lot of it in fact. There is no tone or note as such. Delving into the details made me realise that the ProXS muffler may perhaps be a tad too large for the small-capacity 1.2 TSI, which is the reason for the only-bass-no-pitch exhaust note. Deleting the resonator further compounded the issue as it not only got a whole lot louder, but the drone at 3k RPM was more than apparent and intrusive. It was an absolute pain in the city, and I’m sure I would lose my mind on the open road and highway drives.

The search for a suitable muffler and a nice exhaust note continues, unfortunately.

Stay tuned for more updates.

[roamer012]

Originally Posted by suhaas307

On the day when I had gone back to Blackworks to diagnose the issue, Venkat hooked up the VCDS to the OBD and a few hard runs revealed that the IATs has dropped by a few degrees to around 40 degrees. WOT runs resulted in a temperature spike to around 50 degrees. At first it seemed like the slight drop in IAT was marginal and that there was no real benefit of the additional radiator, but Venkat then noticed that immediately after the WOT run, the IAT which had creeped up to 50 would now fall to the early 40s in a matter of 3 seconds. Before the installation of the additional radiator, any spike in IATs would take at least 30 seconds to about a minute to fall back to acceptable levels.

To be frank i was expecting it to not work when i began to read your post. And your findings also more or less say so. Agreed that the setup is now cooling down faster compared to previous setup however any tangible gains can be confirmed by a dyno run only. My skepticism was not based on some prior experience but from the findings of similar setup but in different conditions

CPU Cooling

.
That said, i do love what you have done with your car and really appreciate your honest findings where in you call a spade a spade instead of glossing over stuff. Can not wait to find out what else you have in store

[suhaas307]

Originally Posted by roamer012

To be frank i was expecting it to not work when i began to read your post. And your findings also more or less say so. Agreed that the setup is now cooling down faster compared to previous setup however any tangible gains can be confirmed by a dyno run only. My skepticism was not based on some prior experience but from the findings of similar setup but in different conditions

I wouldn’t go so far as to say that it doesn’t work. There are a few positive take-aways from the new radiator that perhaps I should have illustrated better in my post:
1. Increased coolant capacity = larger thermal mass
2. Increased radiator surface area = better heat dissipation. Better to have it and not need it than the other way round.
3. Fully reversible besides a hole in the plastic frame.
4. Approximately 10% drop in regular operating IAT. Law of diminishing returns and all that.

So there are some benefits to be had from this. But the biggest benefit I see is the unlocking of possibilities.

For example, I can now consider running a far more aggressive map to take advantage of the improvement in cooling. I could consider even upgrading the turbo - something that a lot of international tuning houses had attempted unsuccessfully due to inadequate cooling.

That said, i do love what you have done with your car and really appreciate your honest findings where in you call a spade a spade instead of glossing over stuff. Can not wait to find out what else you have in store

Thank you

There is a lot in store, rest assured.

However, I am for the moment giving the engine and transmission a break from fiddling and will now turn to the chassis or maybe even cosmetic upgrades. *wink*

[Turbohead]

I honestly didn't expect such drastic results after putting the radiator in front of the existing one. I thought it would be a wasted effort because I assumed air flow around the radiator at the back will be a fraction of the one in front of it.

Glad to know that you're exploiting the limits of that small turbocharged engine. I sincerely hope the DSG gearbox will be as reliable as possible.

Also, can you share details on the Sachs dealer in India?

[roamer012]

Originally Posted by suhaas307

I wouldn’t go so far as to say that it doesn’t work.

Perhaps that came out wrong on my part. The efforts put in by you and Blackworks team are commendable and would be of help for many others reading your posts.

What you have said about increased thermal mass and all is true but that is what i was trying to show to you from the youtube video. IMO gains are definitely there but the quantum is to be determined (As i understand, IAT itself hasn't dropped by that much but the rate of drop in IAT after WOT runs has increased substantially).
As for turbo swap i would double check since the same as confirmed by you has been tried unsuccessfully by many others and the solution being proposed here is also not very revolutionary (Meaning it too must have been tried by others). Also I might be wrong but running two intercooler in series is bound to create drop in boost built up by turbo or increase turbo lag (which itself might be accentuated by bigger turbo).

Nonetheless please do not take my skepticism in negative way. I sincerely hope you are able to plonk down bigger turbo and make this the GTI which was never offered by VW but should have been. Maybe someday people up north also get to enjoy the benefits of talent and workmanship available down south for tuning and modding.

PS - I am in no way expert in thermodynamics and fluid dynamics, all comments made are from my limited power of inference from my engineering days. And for all i know i might be completely wrong in doubting your setup.

[suhaas307]

Originally Posted by Turbohead

I honestly didn't expect such drastic results after putting the radiator in front of the existing one. I thought it would be a wasted effort because I assumed air flow around the radiator at the back will be a fraction of the one in front of it.

Also, can you share details on the Sachs dealer in India?

Originally Posted by roamer012

Perhaps that came out wrong on my part. The efforts put in by you and Blackworks team are commendable and would be of help for many others reading your posts.

What you have said about increased thermal mass and all is true but that is what i was trying to show to you from the Youtube video. IMO gains are definitely there but the quantum is to be determined (As i understand, IAT itself hasn't dropped by that much but the rate of drop in IAT after WOT runs has increased substantially

Both you and Turbohead are absolutely right in your observations. The gains are purely incremental.

After the divorced coolant setup was in place, the gains were noted to be quite significant. We experienced a drop of almost 40 degrees in IAT in Bangalore summer! To make further gains from those figures is not going to be easy at all. I think the fact that we managed to get a further (slight) drop and a significantly improved recovery rate are all the gains I could ask for.

@turbohead: unfortunately I am not in touch with the Sachs dealer in India, but I think a few BHPians who follow this thread may be able to help you with that.

Also, just to clarify, this is not an intercooler upgrade or two intercoolers in series, but two radiators in series.

As for turbo swap i would double check since the same as confirmed by you has been tried unsuccessfully by many others and the solution being proposed here is also not very revolutionary (Meaning it too must have been tried by others). Also I might be wrong but running two intercooler in series is bound to create drop in boost built up by turbo or increase turbo lag (which itself might be accentuated by bigger turbo).

Yes, I believe similar solution for the cooling issue was achieved by a few. Our own member FrankMehta got something similar done to his car a few years ago. There are two other cars in the EU that have explored similar solutions too.

There is one specific tuning firm from EU that could not benefit from the hybrid-turbo upgrade solely because the car was limited by its cooling system. They found that divorcing the coolant circuit would help achieve much higher power figures on their hybrid-turbo setup and hence had made some headway in that department.

Your point on the drop in boost build up or turbo lag is interesting. I’m not sure if my car suffers from lag as a consequence of the radiator upgrade. I haven’t experienced any as such, after the modification. In fact, quite the opposite! I find that the car feels like it’s on steroids!

Having said that, the rattle on the pedals at idle is an issue I’m looking forward to address. And the car is due for a service as I feel the punishment over the summer (data logging, repeated WOT runs and 0-100 runs in the summer) has had some effect on performance.

Nonetheless please do not take my skepticism in negative way. I sincerely hope you are able to plonk down bigger turbo and make this the GTI which was never offered by VW but should have been. Maybe someday people up north also get to enjoy the benefits of talent and workmanship available down south for tuning and modding.

PS - I am in no way expert in thermodynamics and fluid dynamics, all comments made are from my limited power of inference from my engineering days. And for all i know i might be completely wrong in doubting your setup.

Absolutely not, sir! Your scepticism is definitely welcome. I did not sense any negative connotations in your post at all. I am no expert in thermodynamics or fluid dynamics either. I wholeheartedly welcome feedback and you have raised some good / interesting points that are worth pondering over, surely.

Also, there is no way I will be able to achieve GTI levels of performance. I embarked on these upgrades not with the intention to create a replica-GTI, but with the goal to improve upon the car’s drawbacks to the extent possible.

[bhuvan_prasad]

Wow, Venkat and you are really at it, giving it your everything to perfect the setup. It definitely seems to be working, gains will not always be massive beyond a point, but the 30s to 3s drop is good, especially if you're flogging it on a track. Think of it this way, you're flat out, then brake, and by the time you are done with the corner, and back on the power, your IAT's are back to the good, healthy range, and you get full power without the ECU retarding the timing due to high IAT's. On the street, and especially in Bangalore's lovely traffic with severely limited WOT opportunities, you might not find the difference to be night and day, after adding the extra radiator, but it's good knowing the setup exists.

I am no expert regarding the map, but since your IAT's are consistently low, you will see power gains via that, and usually more aggressive remaps for an inter-cooler are not done, as far as I have heard. You will just have more power all the time, rather than more power only for some time, unlike earlier.

Sad that the Borla ProXS muffler didn't work out, it sounds good on my NA 1.5 Honda city VTEC, with no drone. It does get loud post 3000RPM, but that is ok, normal city driving, it is quite discreet.

Originally Posted by roamer012

As for turbo swap i would double check since the same as confirmed by you has been tried unsuccessfully by many others and the solution being proposed here is also not very revolutionary (Meaning it too must have been tried by others). Also I might be wrong but running two intercooler in series is bound to create drop in boost built up by turbo or increase turbo lag (which itself might be accentuated by bigger turbo).

Nonetheless please do not take my skepticism in negative way. I sincerely hope you are able to plonk down bigger turbo and make this the GTI which was never offered by VW but should have been. Maybe someday people up north also get to enjoy the benefits of talent and workmanship available down south for tuning and modding.

The turbo lag will not increase as their has been no modification whatsoever to the factory charge intake flow and piping. This is not an air to air inter-cooler in which the intake charge flows through the core of the intercooler.

I am currently based in Gurgaon, and I hear you on the people up north bit being able to enjoy the benefits of such workmanship. If you are looking to modify a car extensively, with lot of machining and custom design plus fabrication, it makes sense to have your car sent on a maruti truck for 15-20k. I have actually done this and so have a few others, the fun drive back to Delhi is the icing on the cake, and doubles up as a reliability test and good shakedown for the car as well.