Intercoolers

[nicdav]

Hi all,
toying with the idea of Front mount intercooler at the mo for my Fiat coupe16v turbo... I know the standard intercooler is quite limited when it comes to upping turbo pressure, i think there have been a few cases of the PLASTIC inlet and outlet of the intercooler failing with higher than standard boost??
I bought (at start of rebuild) a Lancia delta (all alloy) intercooler which i was hoping to fit in place of my standard one as its a very similar size, i'll just need a clever bit of plumbing..... Was wondering if this intercooler would be adequate for the modifications i've done (hope to be running in the region of 350bhp, with cosworth t34 running no more than 1.4 bar),
ALOT of people have advised front mount, but this means modification of my front bumper which is a bit of a pain....

If a FMIC would be the way to go then so be it, was just wondering If the Lancia intercooler could do the job???

Nick

[Guy Croft]

I'm sorry Nick, I do not know.

There are several experts here that may know a robust answer to this, let's wait and see.

GC

[Walezy]

I had in my Integrale 16v 1,8 bar boost and never had any problem with intercooler but the rubber pipes sometimes exploded :). I am not sure if cooling was enough efficient with that pressure but whole setup was working fine.
By the way, is that possible to get 350HP from only 1,4bar boost?

[nicdav]

Yes, i believe that a guy in greece who i've spoken to on the Fiat coupe forum has made 320 bhp @ the wheels on only 1.2bar boost, from very similar mods as i've got, only difference at the mo is i've only got 440 injector and i'm not mapped yet,
His mods are: Wossner pistons/Pauter/C&B cams/SuperSprint manifold/T304b turbo/630cc injectors/DIY headwork&maps/FMIC/3"dp
He's managed 320whp@1.2bar & 336lb/ft.....
Anyway back on topic... I might give the Integrale intercooler a go then, i'm not gonna be running anywhere near 1.8 bar like you were...
Nick

[Kev Rooney]

The reason for failure on most plastic tanked intercoolers is that the end tanks are only crimped into position as per most automotive radiators. These also suffer from tanks becoming loose due to excess pressure ( failed head gaskets or trapped airlocks ).

A cheap and effective fix for your existing intercoler is to use a ratchet packing strip tool and put several wraps a around that will prevent the tanks lifting and pushing the crimps back. Obviously you need to check that the intercooler is able the flow the amount of boost as a 'blockage' will actually generate extra heat that needs to be removed.

An all welded construction intercooler will be better , and dearer, but these can also suffer from cracking of the tanks due to repeated expansion if inadequate flow for the boost being used.

[SteveNZ]

Any intercooler will work. Chances are it will be far from ideal. Factory intercoolers generally become very restrictive at higher than standard boost and flow. Get it flow tested if you want to be sure

[chicken]

I am assuming that the car will be used for limited competition rather than a daily driver. As much attention as you have put into your engine a lesser intercooler seems out of place. Have to measured your temps after the intercooler?

Plastic end tanks will fatigue differently and there is a likely eventual failure. This is more consistent in high performance systems. The aluminum also adds to the heat mass of the system (a good thing). But true as it is that any intercooler will work I would suggest getting the specific intercooler for your needs. An all aluminum front mounted intercooler is very nice for competition. It does not need to be huge. As the volumetric area becomes larger so too does the time to fill it take longer. The plumbing should be well thought out; diameters, materials, etc. It can be nearly as important as the intercooler. As headers and collectors are a science and art form for some, so too can the intercooler system be executed and yield similar benefits above avearge.

I sympathize with wanting a neat and compact solution as I decided not to use a front mount myself. The heat soak is noticeable. If the engine ever went to a competition level I believe it would only be prudent to use a front mount instead. That may be the next one. =)

[Georges Fonso]

Hello Nick and all,

A front mount intercooler is the obvious easy solution until you get to think about heat soak, stone damage, reduction of airflow to the car's other radiators and so forth, even extra aerodynamic drag for what it's worth... That's why I would definitely try to make the best out of the existing intercooler or the all-alloy Integrale one, even if that calls for extra pipework. How?

First of all, I'd ensure that the intercooler is not causing excessive pressure drop at my intended boost level. Probing before and after the intercooler is really easy, just compare boost gauge readings at the plenum chamber (after the throttle body) and at the turbocharger's compressor housing, by tapping at the wastegate actuator's hose. I would aim for a pressure loss less than 5% of my maximum boost pressure. To stretch it a bit more, i would use a differential pressure gauge, as this would show me the actual pressure loss in real-time without the need to log boost gauge readings under the "same" load and engine speed and then do the substractions or having to substract readings while driving the car at anger and using two identical boost gauges side-by-side... You can get a decent industrial differential pressure gauge for less than 100 Euro if you do your search at industrial automation and instrumentation companies.

Once I've made sure that the intercooler flows OK, it's time to see how much it cools the air. I wouldn't be surprised to see that, at full boost, the air temperature at the turbocharger exit can top that of the engine coolant! Under all circumstances, I wouldn't like to see my charge air temperature rise above 45 degrees C, and that's in summertime weather of 30-35deg C ambient. An intake air thermometer is a must now, and you can get really accurate digital ones, using K-type thermocouples, for very reasonable money, again at industrial equipment factors. Even though a before/after reading is not that important, it will give a better insight as far as the intercooler's thermal efficiency goes. If the turbocharger setup overwhelms the intercooler, and its efficiency drops below 80% {that means we're aiming for (ambient temperature / charge temperature) >= 0.8}, then the intercooler can be regarded as "marginal".

There are still ways to improve the given intercooler's efficiency, though:

1. Make sure the intercooler and its associated piping, at least downstream of its exit, do not get heat soaked by underbonnet temperatures. Insulating them by means of thermal wrap is a convenient method, as well as shielding the intercooler so as to reflect heat by nearby hot components. Also, let's make sure that the engine bay gets adequate venting. Sure, bonnet vents are not always the most neat implementation, but they sure do a very neat job when "strategically"placed...

2. Make sure the intercooler gets as much cold air as possible, by means of air supply openings as well as air directing ducts. It would be nice if one could make some ducting out of sheet metal and fit it on the face of the intercooler core, sealing its surround so that all air goes through the core. An electric fan, on the back side of the core could also help a lot, and the one used by Smart cars for their own intercoolers is a convenient size and adequate flow capacity.

3. Water spray: a hands-on, practical and easy "band-aid" for "marginal intercooling"... Subaru Impreza STIs use a water spray system for their top-mount intercoolers, and to a great benefit too. The Subaru spray nozzles give a spray pattern far superior to most windshield wiper nozzles, and one that is surpassed only by "new-age", "umbrella-spraying" nozzles, like those found on the latest Fiat Punto or VW Golf, for instance. They are also quite affordable, at less than 15 Euros each, at your local Subaru dealer. Two or three of them, aimed in such a way as to cover the entire area of the intercooler core, will work wonders. They can be supplied with water by a simple stand-alone windshield washer pump, tapped to the car's windshield washer tank -- better yet, get a separate tank and pump from the local breakers' and accomodate it in the engine bay or in the trunk. The pump can be actuated either manually or by using a home-made electronic thermostat-timer combo, sensing the inlet temperature and driving a relay connected between pump and battery, for a given time (e.g. 15 seconds) each time the temperature rises above the preset threshold. Designs, component listigns and assembly instructions for such circuits can be fount on the internet. One can even source a do-it yourself kit at Electronics DIY shops.

4. Water injection is yet another fantastic tool, even though its cost alone (referring to a proper system with adequate instrumentation and decent ancillaries) will suddenly make the front mount intercooler seem like a wonderful idea in the first place, indeed!

Best regards,
G.F.