low mount 2560 on a 1.6, currently routing the oil/water lines. oil is done and water feed will come from the block port on the exhaust side. for the water return, i'd like to route it upwards from the turbo to allow for thermal siphoning after shutdown (as Garrett recommends). I also spoke with a friend who is the current turbocharger Design Release Engineer for GM's 2.7L turbo, and he agrees the return line should run above the highest point of the feed line and with no up/down kinks or bends. Also, i have the kraken mixing manifold and the location of the water return port on it might be too close to my turbo intake piping to work.

so the options i'm seeing are to route the return line to the back of the head to either the NPT port on the Supermiata reroute housing or to replace the cursed water plug fitting with an AN fitting and run it to that. an AN fitting on the supermiata block off plate on the front of the head is an option too, but i'd like to keep the front of the engine clutter-free so rear of the head is my preference.

what i am unsure of is, since both the water feed port and the head are pushing water out, would routing the return line to the head cause any significant flow restriction/turbulence or pressure build-up in the chra from water feeding in from both of the lines while the engine is running? or could the flow from the water return line be scavenged by the water draw in the radiator return hose? i just want to be sure i don't end up with two water feed lines pressurizing the chra when the engine is running.
As for water bypassing the thermostat during warm up, car is mostly track duty so warm up times don't matter all that much, but the cursed water plug is pre-thermostat with the supermiata reroute, so that is an option if it's preferable.

am i making a huge deal out of nothing? there's a right and wrong way to everything, and returning below the feed point is wrong in principle, but i know that's the most common water routing for these cars (maybe just due to laziness and simplicity?)

thanks in advance

 

The head and the hole on the hotside of the block are both feeds and neither is a return. As you postulated, the water will not flow if you choose those two. Choose a location on the water pump inlet, the lower radiator hose, the return line of the heater on its way to the water pump inlet, or the end tank of the radiator on the return side.

 

thanks six, i figured as much but wanted a second opinion. water pump inlet/mixing mani might not work due to lack of space between the fitting and turbine intake pipe, but its a "**** it ill do it like everyone else" last resort, and i'll pass on drilling into my $400 radiator or teeing off the rad hose. however the heater core hose option is right there by the turbo and it would allow me to keep the down-to-up flow.. would intercepting the heater core FEED pipe and the heater core FEED hose with one of these guys work? going off the assumption that heater core flow is weak enough to where the water wouldn't just pull a 180 turn back to the chra like in the return-to-head scenario - plus the heater core would almost work as a type of heat sink after shut down. thoughts?

 

What Six said.

I realize feeding it back into the mixing manifold is just putting hot coolant right back into the engine, but it's how it's been done for a long time and it works fine.

 

You could always convert to an electric water pump. I've used a lot of BMW's e90 vintage water pumps and am a big fan, they're only $325. Simple 3 bolt mounting, in and out are ~1.25" barbs. You could control it via AiM's PDM32 with 10" display for $2800, and you could then use a PWM function to regulate water temperature, including running it post shut down with a high-side temp switch to keep the PDM on until water temps cool. You could then use a bypass valve to divert turbo water through the heater core regardless of heater settings during extreme temps, and duct a 4" fan/tube from the front bumper area directly to the HVAC unit, again of course triggered by the PDM. I've also thought about using the half-bridge function to reverse the direction of the fan to aid in warm up during severe cold weather.

Or do what everyone else does and just return it to the mixing manifold. Your choice.

 

judging by the time stamps of your post and mine, i assume this was in response to six?

do you think my idea with the y fitting is incredibly unnecessary and stupid? or am i onto something here lol. the engineer in me cries at the thought of putting it back in the mixing mani because of thermodynamics but i know i should probably follow what everyone else does and be done with it

 

Ideally, forget the block feed and run one line to the SM T/Stat housing and then one to the mixing manifold.

DNM

 

well why didn't anyone tell me it was as easy as doing this? u guys r jerks for gatekeeping this info

 

meh, block feed is the obvious of the two feed options to me. directly next to the turbo, out of the way of anything else in the bay, and i've got it so might as well use it. SM t/stat housing port belongs to my aftermarket water temp sensor anyway

 

Your (2) bolded (by me) statements seem to be contradictory, or else I'm just not understanding.

he agrees the return line should run above the highest point of the feed line and with no up/down kinks or bends statement is correct, although bends are not a big deal.

replace the cursed water plug fitting with an AN fitting, I don't know what plug you mean.

If you are concerned only with shutdown thermosyphoning, the block port to turbo to SM housing would be proper (I am picturing your low mount CHRA to be vertically between those two ports). It may be true that, during running the engine you would get very little flow, but that does not seem to be your concern.

And, I would expect the (2) ports to have slightly different head pressures, so you should get a little bit of flow, even when running.

As far as (2) feed ports being used: Water pump pressure is nothing compared to the static pressure from the temperature and radiator cap. That is a non-issue.

As an example of concept... The ideal that I mentioned above would flow from SM T/Stat port, through the CHRA, to the mixing manifold when the engine is running; driven by the water pump. When the engine is off, the coolant will flow in the opposite direction (from the mixing manifold through the CHRA, to the SM T/Stat) due to thermosyphoning. (assumes that CHRA is hotter than the block, which is the only time of importance).

DNM

 

Correct, replying to Six. Edited my post now to clarify that.

^This one

 

yeah they are. i was willing to move the aftermarket water temp sensor off the SM housing port over to the cursed water plug fitting location if that return path to the SM housing worked. otherwise the temp sensor is staying in that port. sorry for the confusion

he meant up and down bends so as to not have the high point in the system be a bend in the line before reaching the return port.

the cursed water plug on 1.6 miata heads under the dash temp gauge sensor. notorious for springing a leak and a pita to fix because of location. can’t recall why it’s there/what purpose it had in the gtx.



it is vertically between those two locations, but my concern is pressurizing the chra when the engine is running - both the feed and "return" would be feeding water into it. unsure if this is the case or if one flow would just overpower the other as you mentioned, but it would be an expensive experiment to do if it did any damage to the chra.

this is an ideal system and one which i was imagining and curious as to if it would work. except with using the block feed and SM housing port for return. but lacking pressure readings on both ports or some kind of empirical data to base off, its probably not worth the headache to figure out myself.

 

If choosing between flow after shutdown and flow during peak temperature operation, my choice would be clear. Stop worrying about what is easy or what works after shutdown and do the right thing. I don't know a soul who experienced chra bearing failure on an aftermarket turbo because of a height difference in water lines.

Perfect is very often the enemy of good.

 

Okay. Good input Six. Consensus is take outlet to mixing manifold.

The MSM is a low mount turbo with feed from block. The return goes into the metal pipe that runs from the heater outlet to the mixing manifold. So, again, the mixing manifold.





DNM

 

yeah i’m just going to the mixing mani. but that presents its own headache i was trying to avoid




mocking up the intake pipe with a 1.8 crossover tube cause it’s roughly the same as what i’ll have. but there’s almost no room between it and the fitting to the manifold. and that’s before the adapter and water line are there. i might have to get a intake pipe welded to clear the water return



also the oil drain fittings might be too big to have a line between them. might have to ditch the an and do a regular hose barb and rubber hose sadly

 

Plenty of room to work with.

 

Stray information regarding "the cursed water plug on 1.6 miata heads under the dash temp gauge sensor. notorious for springing a leak and a pita to fix because of location. can’t recall why it’s there/what purpose it had in the gtx."

The big outlet tube on the Miata in your pic was in fact the outlet to the radiator on the GTX. So the water plug fed into the return tube, and went back to the mixing point. That return tube also provided an inlet from the turbo, to take its flow to the mixing point. And the beginning of the return tube was connected to the flow from the oil cooler/heater, the heater core, and the intake manifold coolant flow. The return tube was twice the length of the Miata return tube, and had a 90 degree bend around the back of the block.

Just for reference.

I asked Flying Miata if I could use your original plan at the top of this post, and they said they did not think the pressure differential would be high enough. So same answer as given by 6 and others here.(since I bought my turbo kit from them I feel happy to pepper them with questions.)

Truth is I tried it anyhow. Problem was it dumped the high temp fluid from the turbo right onto the temp sensor in the Super Miata coolant reroute, so I had biased temp readings for the ECU. Not so great. It does show it had flow, but it had other problems for the ECU control as a function of temp.