Turbo systems for X1/9's

[Bjorn Nilson]

I am almost sure my turbo works the same way as your T5R. It opens a bypass valve to the non pressured side of the compressor. I found a good video that explains the pros and cons with having a BOV vs a BPV. I will start with the built in BPV and find out if it works as expected even if it cannot be adjusted. Adding a BOV later would be an easy thing if necessary. And for sure the BPV should be connected to plenum.

I have more things to do with the turbo. It has a built in waste gate as well and the rather big actuator is hitting the rear wall. I need a smaller actuator with a straight rod and need to adjust the angle on the compressor side to make it fit. That will make it easier to have the water IC (barrel type) fitted as well.

 

[Bjorn Nilson]

I modified the right vent duct to fit the oil cooler. Unfortunately the UT oil cooler didn't fit but found another 9 row cooler with banjo inlets. It worked out quite well and air flow is surprisingly good (checked with my vacuum cleaner in blow out mode). If you're planning for an oil cooler this might give you some inspiration.

The width of the plastic duct is perfect for a 9 row cooler. I removed the upper part, and made some paper templates and transferred to aluminium sheets.

Finished product.

Finally added a heat shield to reroute the hot air upwards.
I am not sure about how to connect oil inlet/outlet on a cooler positioned like this. Should I connect the inlet hose to the top or bottom? Does it really matters? Please let me know your thoughts.

 

[Dr.Jeff]

I modified the right vent duct to fit the oil cooler.

Nicely done, very clean craftsmanship.
I'm using the same oil cooler. Because of the turbo I wondered if a larger one (more plates) might be even better. But ultimately my arrangement allows me to mount the cooler directly under a electric fan that will cool the intercooler. I think the added air flow of the fan will be more than enough cooling with the existing size unit.

As for the side vents, I've modified mine rather radically to increase the air flow into the engine bay. In these pics they are not finished, still need to do some bodywork to clean things up and attach the scoops to the body:

Should I connect the inlet hose to the top or bottom? Does it really matters?

Your layout positions the cooler ideally. Here is a simple diagram of recommended mounting options for a universal oil cooler:

As for top to bottom or bottom to top, it may depend on the rest of your system. For example what other components it contains. Here are a couple more diagrams:

Still doesn't directly answer the question but maybe you can see how it might depend on other factors. Otherwise I think top top bottom makes the most sense.

 

[Bjorn Nilson]

Still doesn't directly answer the question but maybe you can see how it might depend on other factors. Otherwise I think top top bottom makes the most sense.

I've searched the net for information about inlet/return placement with no luck. But found an interesting study in general oil cooling from University of Uppsala. https://uu.diva-portal.org/smash/get/diva2:825739/FULLTEXT02.pdf

I also think that top to bottom makes sense. -Less oil pressure would be needed to fill and rotate the oil trough the cooler that way. To prevent cooler from draining when not in use (below 76 degrees Celcius), I will mount the return line in an arch to have feed/return lines at the same level.
At first I tried a cooler with a fan but it was too big and didn't fit. Instead I went for a narrower but taller 9 row cooler. But I still want a fan and I found a pushing 5.2'' Spal that I am planning to fit under the hood right above my ''heat sink''. If there is room enough I will even have two of them as they can serve as injector coolers as well.
I like your big scoops. They look big enough to even host a cooler with a fan. But I assume you are going to attach them permanently to the body?

 

[Dr.Jeff]

found an interesting study in general oil cooling

I only read the summary (the rest needs to be translated first), and it sounds like their "best" solution was to add a second oil cooler after the existing one. Isn't that the same as just using a larger oil cooler in place of the existing one? But I may be missing more details in the body of the report.

They look big enough to even host a cooler with a fan. But I assume you are going to attach them permanently to the body?

Yes the scoops will be a permanent part of the bodywork (it is just taped on in the pic). And having the oil cooler inside it would make access difficult. But with the cooler mounted under a fan it offers cooling air at all times. That should prevent heat soak when the vehicle is stopped or not moving quickly. That is one possible issue with relying on just the side scoop for cooling air flow. But I don't think it will be a real issue, I tend to over design things.

The large side scoops and opened ducts are part of a overall plan to manage thermal levels in the engine bay. In addition to these scoops the engine cover (bay lid) will be a open mesh to allow free air movement, the bulkhead between the engine bay and the rear trunk has been completely cut out for a open flow rearward, the rear taillight panel has also been cut open (with another mesh grill) for rear exit of air. The intercooler and oil cooler will lay flat over the area above the transmission; between the front firewall, left strut tower and the intake manifold. The fan is mounted to drive air across those coolers, with ducting to then direct the airflow toward the turbo and out the back of the car. The undercarriage will be covered to help control this direction of flow. The intent is cool air travels from the sides and top, through the bay (as described), and out the (low pressure) rear.

 

[lookforjoe]

I am almost sure my turbo works the same way as your T5R. It opens a bypass valve to the non pressured side of the compressor. I found a good video that explains the pros and cons with having a BOV vs a BPV. I will start with the built in BPV and find out if it works as expected even if it cannot be adjusted. Adding a BOV later would be an easy thing if necessary. And for sure the BPV should be connected to plenum.

I have more things to do with the turbo. It has a built in waste gate as well and the rather big actuator is hitting the rear wall. I need a smaller actuator with a straight rod and need to adjust the angle on the compressor side to make it fit. That will make it easier to have the water IC (barrel type) fitted as well.

Sorry, I didn't catch your earlier request for input - as I'm sure you now know, the valve is connected to the plenum, as close to the TB as possible. The diaphragms tend to tear/rot with age, so you should dismantle it (if you haven't already) and flex the diaphragm through it's range of motion to check fo cracks from the outer ot inner layers. It is possible to raise boost bleed off by putting a stiffer spring, and/or shimming the existing spring to increase tension & therefore resistance to opening. There used to be kits for that. I probably still have one of the shim kits from waaaay back when I ran factory TD04HL turbos.

 

[lookforjoe]

Nicely done, very clean craftsmanship.
I'm using the same oil cooler. Because of the turbo I wondered if a larger one (more plates) might be even better. But ultimately my arrangement allows me to mount the cooler directly under a electric fan that will cool the intercooler. I think the added air flow of the fan will be more than enough cooling with the existing size unit.

As for the side vents, I've modified mine rather radically to increase the air flow into the engine bay. In these pics they are not finished, still need to do some bodywork to clean things up and attach the scoops to the body:
View attachment 33271View attachment 33270

Looking Good, Jeff! Don't see examples of your thorough work very often - That opening looks very nicely finished!

The size of the stock opening would be a concern for me, when relying on it for either an IC or OC. So little air is actually fed through the side vents in stock form.

 

[Ulix]

Wouldn't an oil flow bottom to top help to get any air out of the oil cooler?

 

[Bjorn Nilson]

Wouldn't an oil flow bottom to top help to get any air out of the oil cooler?

That's what I am wondering about as well. At least in theory air in the cooler would escape much easier. But I think more oil pressure is needed to push the oil trough the cooler from bottom to top. I hope for more comments on this subject and will wait fitting the AN hoses.
I am following this thread with interest.

 

[Janis]

That's what I am wondering about as well. At least in theory air in the cooler would escape much easier. But I think more oil pressure is needed to push the oil trough the cooler from bottom to top. I hope for more comments on this subject and will wait fitting the AN hoses.
I am following this thread with interest.

At my understandings there is absolutely no matter in point of pressure - is inlet on top or bottom, because height of the highest point from pump is same.

Centimetre or millimetre of water - Wikipedia

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Ūdens staba metrs — Vikipēdija

lv.m.wikipedia.org

 

[rachaeljf]

Oil flow from bottom to top will be marginally better for self-bleeding, but with the viscosity of oil and the size of the oilways, a top to bottom flow will self-bleed anyway.

 

[Dr.Jeff]

I'm with @mkmini and @rachaeljf , if there is air in there then it will travel back to the engine one way or the other - it's a closed system so there is no bleed off - the same air will go through it either direction. Furthermore as the hot oil drains back (after shutdown), it will drain back the same amount and same direction regardless of hose orientation (gravity flow with engine off). The only possible difference is what I alluded to earlier, if you have other components tied into the system; for example an external thermostat or remote oil filter. Then the relative location of those components might affect oil drain back to some extent.

Same is true for the oil pressure - the workload required by the pump to flow from top to bottom vs bottom to top. The oil has to travel the same distance and elevation either way, so it is the same workload on the pump. Again, it is a closed system so no difference.

I'm more concerned with the height of the oil cooler compared to the inlet/outlet on the engine block. Not in terms of pressure but in terms of flow. I'm using an adaptor mounted in place of the stock oil filter, so the oil supply and return (for the cooler) are pretty much at the lowest point of the system. My cooler will be considerably higher up in the engine bay to take advantage of a better cool air flow, i.e. above the oil level in the crankcase. That means after shut down the oil will want to drain back from the cooler into the engine. So on start up it will take longer for the oil cooler to refill before feeding the oil back to the engine. Is there a low restriction one-way check-valve that can be attached to the lines at the adaptor plate (to retain oil in the cooler system)?

 

[Dr.Jeff]

The size of the stock opening would be a concern for me, when relying on it for either an IC or OC. So little air is actually fed through the side vents in stock form.

And perhaps even more so when the vehicle isn't moving. Seems heat soak may take place inside the air box around the cooler. Then the somewhat limited air flow of the smallish stock openings will have a very difficult time removing all of that heat. Therefore I agree with the idea of adding a fan to it, as @Bjorn Nilson said: "But I still want a fan and I found a pushing 5.2'' Spal that I am planning to fit"

 

[Dr.Jeff]

Speaking of "heat soak" after the engine is shut down....

Engine bay thermal management is a big task with the X's design, particularly when more heat is being generated by a performance engine. There are a couple ways to avoid this; have a electric water pump that continues to circulate coolant after the engine is off, or a electric fan to push the hot air out of the bay after shutdown. Obviously the fan approach is much more practical. Another approach with turbo engines is a "turbo timer". Essentially it keeps the engine running for a specified period of time after the key switch is turned off. The idea is the continued circulation of coolant and oil will bring down the temp as it idles. Personally I don't like this approach, but it works well as far as thermal management is concerned.

For my "TurboX" project I will use a electric fan to cool the intercooler and oil cooler. The air will then be ducted toward the turbo area to push the heat out the back of the car (open rear panel). So having that fan run-on after engine shutdown will serve two benefits; reduce the temps of the coolers and extract the hot air from the bay. Both will help to avoid heat soak.

In a previous discussion @lookforjoe described a timer module to allow the cooling fan to run-on after engine shutdown. I've been contemplating using a temp switch instead of a timer. Several manufacturers have done it this way. Lots of VW's used a switch like this:

Mounted in the cooling system, it is a simple grounding switch set at a specified temp. For this circuit, the fan is wired with constant power so it will run until the temp of the switch is reached and the ground is cut - regardless of ignition key position. Different temps are available. The principle is the same as with the X's injector (or carb) cooling blower switch.

The possible drawback is if it takes a really long time to cool down then it will partially drain the battery. But in terms of thermal management it's benefits preventing heat soak are worth it. Especially in situations like the turbo engine where a LOT of heat is generated and the oil will 'coke' and clog the passage if the temp isn't brought down.

But I keep debating if it will be better to use a timer or a temp switch to control how long the fan runs on. Or maybe someone has a even better approach?

 

[rachaeljf]

Hi Jeff, with a water cooled turbo the trick is to keep some coolant circulating through it after shut down, rather than running the rad fan or an engine bay fan. This can be achieved with a circulating pump, or in the case of the Uno Turbo, a phase change (i.e. boiling the coolant) thermosiphon. With an oil cooled turbo you need a "turbo timer" or other means to idle the engine to cool things down, or an auxiliary oil pump.

The UT method is quite clever. The turbo coolant return pipe goes from the top of the turbo centre housing to the top of the header tank, i.e. it returns coolant above the normal coolant level in the header tank. With the engine running a constant flow of coolant is obtained. With the engine stopped, the coolant level in the turbo to header tank pipe settles at the same level as the coolant in the header tank, with an air space above. If the turbo centre housing gets too hot from heat soak, the coolant boils in the housing and instantly lowers the liquid level in the turbo to header tank pipe. To correct the levels, coolant from the engine rises up into the turbo from below. Thus heat is removed from the turbo until the temperature is below the boiling point of the coolant and the oil doesn't get carbonised.

 

[lookforjoe]

I'm more concerned with the height of the oil cooler compared to the inlet/outlet on the engine block. Not in terms of pressure but in terms of flow. I'm using an adaptor mounted in place of the stock oil filter, so the oil supply and return (for the cooler) are pretty much at the lowest point of the system. My cooler will be considerably higher up in the engine bay to take advantage of a better cool air flow, i.e. above the oil level in the crankcase. That means after shut down the oil will want to drain back from the cooler into the engine. So on start up it will take longer for the oil cooler to refill before feeding the oil back to the engine. Is there a low restriction one-way check-valve that can be attached to the lines at the adaptor plate (to retain oil in the cooler system)?

Aren't you using a thermostat housing adapter under the oil filter? That would resolve the issue, since it won't even open until the temp gets up there.

 

[Dr.Jeff]

Thanks @rachaeljf. Actually I am using a UT's turbo unit with water cooling. And I hopefully have it plumbed to be able to function like the UT in terms of thermosiphon. But I like to over do things and wanted a little more positive way of removing the heat after engine shutdown. Considering I'll already have a fan installed for other purposes, and it will direct air toward the turbo before exiting the bay, that seems like a easy way to add assurance that things cool down. It really won't hurt to have it wired for some after run. The question is which method of control to choose.

The thermosiphon principle is how they used to design dirt bike cooling systems when 'water cooling' first appeared on them. There wasn't a water pump, just the cycling of coolant due to heat differentials in the radiator vs the engine. Worked pretty well. But things progressed and a actual pump was added to the system. In a way that's what I'm hoping to do - make it a little more modern design.

 

[Dr.Jeff]

Aren't you using a thermostat housing adapter under the oil filter?

Actually no. But it likely would be better to have one. However given the turbo is oil and water cooled and adds a lot of heat to the oil and coolant in a hurry. Plus the added boost to the SOHC will increase thermal load. I figure a oil thermostat isn't really needed, it will warm up very quickly. At which point the decreased resistance in flow (without a t-stat) is a benefit. But your point is good about it acting as a drain back valve.

I have a t-stat controlled oil filter adaptor plate on my VW engine to feed the external oil cooler and remote filter. But that's a NA setup, front engine, huge radiator, and great water pump (compared to the Fiat's). So warmup will be much slower.

 

[Dr.Jeff]

I just saw a thread by LarryC regarding the engine cooling fan for the '79 carb'ed X. It has a similar temp switch to the ones I posted about earlier, allowing the cooling fan to kick on after engine shutdown until a set temp is reached. The rate of temp drop is amazing:

Carb/intake Cooling Fan Temp Measurements

I was in the garage after a hot run today (90s ambient) and decided to record the drop in intake temperature after the carb cooling fan kicked in. I placed the thermocouple on the base of the carb on the side facing away from the air flow. The temperature drop is spectacular, and then levels...

xwebforums.com

Supports the benefit of a fan in the engine bay to help thermal management.

 

[lookforjoe]

Thanks @rachaeljf. Actually I am using a UT's turbo unit with water cooling. And I hopefully have it plumbed to be able to function like the UT in terms of thermosiphon. But I like to over do things and wanted a little more positive way of removing the heat after engine shutdown. Considering I'll already have a fan installed for other purposes, and it will direct air toward the turbo before exiting the bay, that seems like a easy way to add assurance that things cool down. It really won't hurt to have it wired for some after run. The question is which method of control to choose.

The thermosiphon principle is how they used to design dirt bike cooling systems when 'water cooling' first appeared on them. There wasn't a water pump, just the cycling of coolant due to heat differentials in the radiator vs the engine. Worked pretty well. But things progressed and a actual pump was added to the system. In a way that's what I'm hoping to do - make it a little more modern design.

I would say it is essential the thermosiphon aspect is plumbed correctly, since you want to draw the heat from inside out. Blowing air from the outside may help in terms of bay heat management, but it won't do anything for turbo longevity. The rapid oil coking that occurs with non-water cooled turbos is impressive - unless you have a timer to run the motor for x minutes prior to shutdown. I tried to find a Volvo schematic that clearly shows the height relationship of the water circuit relative to the block & coolant reservoir - no luck. As long as the turbo water passage (lower port) is fed from the coolant return pipe, and outputs (upper port) to the air cavity of the coolant tank, all should be well.