I say go for it and take one for the team. I cant imagine shaving the gaskets will harm anything but I would be super careful and use a mini dremel sanding bit.
The build is coming along nicely, due to poor cooling would you consider a dual cooling setup, for instance 2 seperate reservoirs, split the radiator into 2 and run a seperate pump including the original, 1 system cooling cylinder 1+2 and a seperate one for 3+4, and split the other peripherals throughout each loop
Hi LUKE = i put a ej207 jdm sti , virgin block into my 2001 forester - did heads with brian crower guides springs valves - s/s swirl polished viton seals - and 5,500 klm did the no 4 by-pass coolant upgrade - i could tell a differance with in 5 klm drive - i have big radiator new new new everything - great modification instant benefit = thank you paramedic life subaru saver LUKE !
Opening up the slots in the gasket might affect the back pressure in the lower area of the block (because of the restriction created by the smaller slots), which could possibly could make the flow issue around cylinder 4 even worse (more stagnation) by making the path of least resistance around cylinder 2. Although, I believe that if you open the one near the rear of cylinder 4, you might could increase flow there a tiny bit more. It also looks like there is a fairly dead area of flow around the top of cylinder 2 (flow wise). I used to have access to computer modeling software that would calculate approx flow lines in 3D models to locate the "stagnant" areas where flow velocity is approximately zero (eddies). This would be fun to model.
Your 100% right and you hit one of the key points I’m going to highlight in the closing video to this series. Way to stay on top of all this and connect the dots man. Brilliant. 😁
This is a great series. I discovered the coolant mod a few months ago and thought it was brilliant plus the getadomtune guy has a patent pending on it. There's no way that it wouldn't work and it's a great preventative mod. Also, I haven't thought about modding the head gasket and I'm considering doing that, too. It's like porting your manifolds to match the gasket except the other way around. If it isn't done haphazardly, it can be beneficial. Think about the extra pressure and turbulence on that part of the head gasket that's not even necessary.
I get the point with the cooling mod and the negative pressure etc. But like you say, coolant will circulate the path of least resistance as it is forced around the engine. Its a lot easier for the coolant to escape through the mod pipe into the heater pipe then it is to force itself through the jackets into the rear of the cylinders and up through the exit port. I feel like this mod would be beneficial for the lower half of the cylinder but it would only slow down coolant movement to the top. It seems to me the sensible thing Is to port the gaskets and leave it at that.
Thanks buddy! This is actually my field of expertise professionally. Have a masters in fluid mechanics and hydrologic engineering - applying those concepts to our Subaru engines has been really rewarding and it allows me to create some unique content (I think). Cheers!!!
@@SubaruONLY I actually looked at studying hydrodynamics at uni with a view of applying it to a motorsport engineering degree there after. Partying got the better of me in 6th form though 😂 really cool to see this level of detail though and its somthing I geek out over. More suspension geometry and setups along with weight reduction though these days 😅 applying this kind of thinking and theory to road cars is somthing that I'm crazy into at the moment anyway, so it's awesome to see someone else with such a keen eye for details that make a car
great info. about cyl.4 going out first due to the knock sensor being right next to it. learned a thing or two. thanks. Also, i got my getadomtune hose. just gotta find time to install it before i start to upgrade more parts to my baja turbo.
Good fluid flow explanation. I'm pretty sure sure you're familiar with Navier-Stokes, Bernoulli equations lol. Anyway the coolant flow asymmetry favouring one cylinder over the other is clear. Subaru's idea of a sacrificial cylinder (number 4) for knocking also seems odd. Sometimes I wonder what their engineers were thinking. Btw did they make the head gasket slots smaller to help prevent gasket blowouts? But the pressure from the coolant flow through behind the restriction will try to lift that gasket lip up, maybe damaging it in the process. It's all a bit weird. Very interesting though. Great vid.
I don't know if anyone has mentioned it, and it seems that this is over a year old now...but I believe the coolant passages on the headgasket are sized like that for a VERY specific reason. That is, metering coolant flow. If the ports are too big, the coolant will flow too fast and not spend enough time absorbing heat from the head/block. FelPro has a good article explaining this. Let me know what you think!
May be a year old, but certainly still worth discussing! Yes, 100% agree with you, especially about the time the coolant needs to spend inside the head to absorb heat from the head surface. That still leaves the problem of preferential flow due to inlet and outlet port locations. Any thoughts on that one?
@@SubaruONLY It seems like it might just be a design flaw like you discussed. It's clear that having the huge intake/exhaust ports of the coolant flow cause the path of lease resistance. So the water flows there first and doesn't leave much flow on cylinder 4. Looking into a few different type of cooling system designs, it seems this is a more parallel path. I'm working on an inline 4 cyl engine now that has a series path cooling system. The coolant flows through the block and then enters the head on cyl 4. Then flows back towards the front of the engine in the head. Hopefully that makes sense! I'm not sure about boxer motor design, but it seems like this might be the only way to do it reasonably.
Yes, likely a constraint with the design and local of all the ports. Yes, that inline description make sense. Sounds cool, this for a Motorsport application?
Great video! Just wondering if you're running an oil-cooled only turbo setup, would any modifications needed to be done to the opposite head so the flow isn't impeded? I'm assuming that since the turbo is on that side and has coolant flowing to it from the back of the head, it's helping flow coolant over cylinder #3, correct? Would you just route the turbo coolant feed straight my AOS then back to the upper-coolant reservoir, basically bypassing the turbo section completely since it's no longer needed?
I know this was a year ago, but I definitely would not work to increase flow of the coolant. Those restrictions are deliberate. Their purpose is to increase the amount of time the coolant has to pull heat from the engine, and in turn increase the time the radiator has to pull heat from the coolant.
But when you install the reverse coolant mode, wouldn't that starve the inner side of the 4th cylinder head side by not allowing the coolant to reach it?
Hey Luke, This is really an excellent add to the body of information for EJ motors. i tried to look for a coolant flow diagram but failed. nothing like the oil flow diagram thats out there. Thank You!
Hi mate im just asking why my subaru impreza 2002 radiator coolant hot on top and boiling but on below is cold, but when I removed the thermostat its still open meaning pump failing or head gasket?
Need help, so I installed a 4 cylinder cooling mod then I put a 6-7L Subaru OEM coolant, did the burp but for some reason my coolant reservoir didn’t change still empty even I put 6-7L of Coolant? Any guess?
I've never seen anyone modify the head gaskets before. Is there some documentation to this or are you just considering it? Would this cause any issues with the water pump? I have no idea how good the pumps are.
So what's your opinion on the strategy for Subaru not to use cylinder 4 cooling mod for the purpose of letting it runner hotter for better knock control?
Are you referring to letting cyl #4 run hotter for better knock control? I don’t think that’s an accuse statement, from my understanding, the heat build up in #4 creates conditions where knock become less controlled and more inconsistent. Also, tangential question, you sound like you have some serious experience in this area, if you don’t mind me asking, what’s you background with these engines? You an engine builder or high performance machinist, just curious. No replacement for real world experience in my opinion, that’s a 10X when it comes to one’s options, especially when there’s so many messages board experts out there. Thanks again and cheers!!!
@@SubaruONLYI'm an inventor. Built and owned a few EJ207 swapped cars. EJ runs one knock sensor; FA uses two (like most modern engines) --leading me to believe Subaru engineers are trying to improve knock control. Just a theory. I'll be testing my first prototype for a new EJ cooling system design this month. If all works well, maybe I'll send you a kit to try out?
Great Video!!! Got a question. Are there any benefits of installing a reverse coolant mod in a EJ253 2.5L SOHC? I'm In the middle of doing a Head Gasket Job and while the heads are at the Machine Shop it would be a great time to install one if there are some. Thanks for any info.
Really been enjoying your videos, I'm looking at picking up a 98 legacy wagon as a little project car. My plan is to go all the way to the short block and possibly build from there; pistons, rods, bearings and all that. Was wondering if you could make a guide on ordering OEM parts. Subaru's diagrams are confusing to me and it's hard to tell what actually comes with the parts you order. Thanks!
Any thoughts on whether the reverse cooling mod is necessary on a Supercharged NA car? I think if you did it, you'd need/want to do it on both cylinders 3 and 4?
I really appreciate everything you do on your channel, you go out of your way to make people comfortable working on their Subaru. But, Please, Please, Please, STOP calling this a "reverse" cooling mod. This is just spreading more misinformation within the Subaru community. There is more than enough misinformation ( and just plain bad ideas ) in the online forums. This "mod" does not "reverse" the flow of coolant. You actually had it right at one point in your video when you stated that it allows a second outlet for the NORMAL flow of coolant. All this "mod" does is take advantage of the built in cooling port that would normally be used anyway if the head was in a non-usdm turbo Subaru (right hand drive). Anyone can simply look this up in the shop manual for jdm vs. usdm models. And, as a point of responsibility, you should point out that the pressure differential this would create will reduce the flow to the other side of the engine. Which could raise the average running temp on that side by 1-2deg c. Which also affects how hot the turbo cartridge will run ( and thus its usable lifetime ) since it is the recipient of water flow from this exact same port in the other head. "Reverse" cooling is where the flow from the pump goes directly into the heads, then through the blocks water jacket and out to the radiator. You should know this from your involvement in other motorsports. And, as a suggestion, since you are an engineer, you may want to run a few numbers before getting out your cutters. I think you will find that modifying the head gaskets may only give 1-2deg c improvement ( if that ). I really want to see your channel succeed. There are so few people showing old-school Subi-love anymore. Please take more care in your research and presentation on your videos. As it stands, by attaching your IRL professional credentials to this video, you actually make yourself look bad because you are propagating misinformation. You are also putting your current employment at risk, as more and more companies are letting go of employees when they find out that they are producing media on any of the social media platforms other than LinkedIn. Signed, A concerned car enthusiast and TH-cam citizen.
Getadomtune.com He is the originator of the mod. He chose the diameter of the mod carefully to make the most of it. Don't just grab some fittings and throw them on. Do it right and get the results.
I say go for it and take one for the team. I cant imagine shaving the gaskets will harm anything but I would be super careful and use a mini dremel sanding bit.
The build is coming along nicely, due to poor cooling would you consider a dual cooling setup, for instance 2 seperate reservoirs, split the radiator into 2 and run a seperate pump including the original, 1 system cooling cylinder 1+2 and a seperate one for 3+4, and split the other peripherals throughout each loop
Hi LUKE = i put a ej207 jdm sti , virgin block into my 2001 forester - did heads with brian crower guides springs valves - s/s swirl polished viton seals - and 5,500 klm did the no 4 by-pass coolant upgrade - i could tell a differance with in 5 klm drive - i have big radiator new new new everything - great modification instant benefit = thank you paramedic life subaru saver LUKE !
Opening up the slots in the gasket might affect the back pressure in the lower area of the block (because of the restriction created by the smaller slots), which could possibly could make the flow issue around cylinder 4 even worse (more stagnation) by making the path of least resistance around cylinder 2. Although, I believe that if you open the one near the rear of cylinder 4, you might could increase flow there a tiny bit more. It also looks like there is a fairly dead area of flow around the top of cylinder 2 (flow wise). I used to have access to computer modeling software that would calculate approx flow lines in 3D models to locate the "stagnant" areas where flow velocity is approximately zero (eddies). This would be fun to model.
🎯
Your 100% right and you hit one of the key points I’m going to highlight in the closing video to this series. Way to stay on top of all this and connect the dots man. Brilliant. 😁
Correct, the gasket "slotting" allows Subaru Engineers to fine tune the coolant flow through the engine.
Subaru p/n 21170AA020 - PLUG-WATER BYPASS is the OEM fitting for the no4 cylinder head plug. Add on a small length of hose & a tee from eBay- sorted.
This is a great series. I discovered the coolant mod a few months ago and thought it was brilliant plus the getadomtune guy has a patent pending on it. There's no way that it wouldn't work and it's a great preventative mod. Also, I haven't thought about modding the head gasket and I'm considering doing that, too. It's like porting your manifolds to match the gasket except the other way around. If it isn't done haphazardly, it can be beneficial. Think about the extra pressure and turbulence on that part of the head gasket that's not even necessary.
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
amazing explanation, appreciate your efforts and time, man
Thanks buddy. Got more coming soon!
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
I get the point with the cooling mod and the negative pressure etc. But like you say, coolant will circulate the path of least resistance as it is forced around the engine. Its a lot easier for the coolant to escape through the mod pipe into the heater pipe then it is to force itself through the jackets into the rear of the cylinders and up through the exit port. I feel like this mod would be beneficial for the lower half of the cylinder but it would only slow down coolant movement to the top.
It seems to me the sensible thing Is to port the gaskets and leave it at that.
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
Very good information, I really appreciate the indeath breakdown on cylinder 4.
I'll be installing my cooling mod sometime next week! 😎
Nice. It’s a good idea!!! 👍 still big proponent for these upgrades.
Love your explanation of the coolant taking the path of least resistance 👍 and how the cooling mod helps
Thanks buddy! This is actually my field of expertise professionally. Have a masters in fluid mechanics and hydrologic engineering - applying those concepts to our Subaru engines has been really rewarding and it allows me to create some unique content (I think). Cheers!!!
@@SubaruONLY I actually looked at studying hydrodynamics at uni with a view of applying it to a motorsport engineering degree there after. Partying got the better of me in 6th form though 😂 really cool to see this level of detail though and its somthing I geek out over. More suspension geometry and setups along with weight reduction though these days 😅 applying this kind of thinking and theory to road cars is somthing that I'm crazy into at the moment anyway, so it's awesome to see someone else with such a keen eye for details that make a car
Nice man. Feel you, can’t help it. Cheers!
great info. about cyl.4 going out first due to the knock sensor being right next to it. learned a thing or two. thanks. Also, i got my getadomtune hose. just gotta find time to install it before i start to upgrade more parts to my baja turbo.
Sick car. Love those Baja turbo models. Bucket list car for me for sure!!! 😁😁😁
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
Good fluid flow explanation. I'm pretty sure sure you're familiar with Navier-Stokes, Bernoulli equations lol. Anyway the coolant flow asymmetry favouring one cylinder over the other is clear. Subaru's idea of a sacrificial cylinder (number 4) for knocking also seems odd. Sometimes I wonder what their engineers were thinking.
Btw did they make the head gasket slots smaller to help prevent gasket blowouts? But the pressure from the coolant flow through behind the restriction will try to lift that gasket lip up, maybe damaging it in the process. It's all a bit weird. Very interesting though. Great vid.
Sorry I missed this. GREAT comment, I wonder the same thing. Cheers!!! Hope all is well.
I don't know if anyone has mentioned it, and it seems that this is over a year old now...but I believe the coolant passages on the headgasket are sized like that for a VERY specific reason. That is, metering coolant flow. If the ports are too big, the coolant will flow too fast and not spend enough time absorbing heat from the head/block. FelPro has a good article explaining this. Let me know what you think!
May be a year old, but certainly still worth discussing! Yes, 100% agree with you, especially about the time the coolant needs to spend inside the head to absorb heat from the head surface.
That still leaves the problem of preferential flow due to inlet and outlet port locations. Any thoughts on that one?
@@SubaruONLY It seems like it might just be a design flaw like you discussed. It's clear that having the huge intake/exhaust ports of the coolant flow cause the path of lease resistance. So the water flows there first and doesn't leave much flow on cylinder 4. Looking into a few different type of cooling system designs, it seems this is a more parallel path. I'm working on an inline 4 cyl engine now that has a series path cooling system. The coolant flows through the block and then enters the head on cyl 4. Then flows back towards the front of the engine in the head. Hopefully that makes sense! I'm not sure about boxer motor design, but it seems like this might be the only way to do it reasonably.
Yes, likely a constraint with the design and local of all the ports. Yes, that inline description make sense. Sounds cool, this for a Motorsport application?
Great video! Just wondering if you're running an oil-cooled only turbo setup, would any modifications needed to be done to the opposite head so the flow isn't impeded? I'm assuming that since the turbo is on that side and has coolant flowing to it from the back of the head, it's helping flow coolant over cylinder #3, correct? Would you just route the turbo coolant feed straight my AOS then back to the upper-coolant reservoir, basically bypassing the turbo section completely since it's no longer needed?
is the return pipe(black hard line) have the hose that goes to the top port on the heater core?
I know this was a year ago, but I definitely would not work to increase flow of the coolant. Those restrictions are deliberate. Their purpose is to increase the amount of time the coolant has to pull heat from the engine, and in turn increase the time the radiator has to pull heat from the coolant.
Yes, coolant needs to have the residency time in the heads to absorb enough heat. Agree. Cheers buddy!!!
But when you install the reverse coolant mode, wouldn't that starve the inner side of the 4th cylinder head side by not allowing the coolant to reach it?
Don't think so.
It doesn't starve the inner side of cyl3.
I have a ej25 and I spon a baring can I put a ej207 crank on my ej25
Hey Luke, This is really an excellent add to the body of information for EJ motors. i tried to look for a coolant flow diagram but failed. nothing like the oil flow diagram thats out there.
Thank You!
Thank you. That’s pretty much the same reason I decided to make the videos on this subject. Not much out there. Cheers buddy! 👊
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
Hi mate im just asking why my subaru impreza 2002 radiator coolant hot on top and boiling but on below is cold, but when I removed the thermostat its still open meaning pump failing or head gasket?
Yes, your on the right track. Most likely one of those two issues causing the over heat. Good luck! 👍
Need help, so I installed a 4 cylinder cooling mod then I put a 6-7L Subaru OEM coolant, did the burp but for some reason my coolant reservoir didn’t change still empty even I put 6-7L of Coolant? Any guess?
Even I put coolant in the reservoir between full and low lvl line, every time I drive it it’s go back to the very bottom of low lvl
I’d keep adding coolant till it stop dropping in the secondary reservoir. Must still have some air pockets.
And good luck!!!
I've never seen anyone modify the head gaskets before. Is there some documentation to this or are you just considering it? Would this cause any issues with the water pump? I have no idea how good the pumps are.
So what's your opinion on the strategy for Subaru not to use cylinder 4 cooling mod for the purpose of letting it runner hotter for better knock control?
Are you referring to letting cyl #4 run hotter for better knock control? I don’t think that’s an accuse statement, from my understanding, the heat build up in #4 creates conditions where knock become less controlled and more inconsistent. Also, tangential question, you sound like you have some serious experience in this area, if you don’t mind me asking, what’s you background with these engines? You an engine builder or high performance machinist, just curious. No replacement for real world experience in my opinion, that’s a 10X when it comes to one’s options, especially when there’s so many messages board experts out there. Thanks again and cheers!!!
@@SubaruONLYI'm an inventor. Built and owned a few EJ207 swapped cars. EJ runs one knock sensor; FA uses two (like most modern engines) --leading me to believe Subaru engineers are trying to improve knock control. Just a theory. I'll be testing my first prototype for a new EJ cooling system design this month. If all works well, maybe I'll send you a kit to try out?
For sure man. Send me an email and we can touch base and correspond there, cheers and looking forward to seeing the results!
Great explanation. Thanks for the videos they are very helpful
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
Great Video!!!
Got a question. Are there any benefits of installing a reverse coolant mod in a EJ253 2.5L SOHC? I'm In the middle of doing a Head Gasket Job and while the heads are at the Machine Shop it would be a great time to install one if there are some. Thanks for any info.
Prob not really needed for a stock engine tune. But couldn’t hurt either.
Really been enjoying your videos, I'm looking at picking up a 98 legacy wagon as a little project car. My plan is to go all the way to the short block and possibly build from there; pistons, rods, bearings and all that. Was wondering if you could make a guide on ordering OEM parts. Subaru's diagrams are confusing to me and it's hard to tell what actually comes with the parts you order. Thanks!
Sorry for the late response. I’ll put together a guide on this for sure. And BTW, I’m back!!! 😎
The issue could be warping... never seen anyine doing it before.
Any thoughts on whether the reverse cooling mod is necessary on a Supercharged NA car? I think if you did it, you'd need/want to do it on both cylinders 3 and 4?
Think it would be a good idea for sure. Ever do it?
So the reverse coolant mod actually has real benefits?
I think so. I use it on all my subies.
Interesting thx!
Fuckin love the intro.
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
I’d like this guys videos so much more if it wasn’t for the constant hand motions..
Please continue
Late comment here (BIG TIME, lol) - I did a whole series. Hope you’ll check it out. And BTW, I’m back producing lots of content!! Cheers!!!
I'd love to show you some photos of the work I've been doing on my Version 5 Type RA V Ltd ; )
Think we’re chatting now over email - thanks for sharing! And please keep the correspondence coming. Love it!! 👊
@@SubaruONLY Will do, mate! Glad you like the car!
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
I'm worried about my engine now lol!
Lol cylinder #4 is where my head gasket blew out on my coupe
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
I really appreciate everything you do on your channel, you go out of your way to make people comfortable working on their Subaru. But, Please, Please, Please, STOP calling this a "reverse" cooling mod. This is just spreading more misinformation within the Subaru community. There is more than enough misinformation ( and just plain bad ideas ) in the online forums.
This "mod" does not "reverse" the flow of coolant.
You actually had it right at one point in your video when you stated that it allows a second outlet for the NORMAL flow of coolant.
All this "mod" does is take advantage of the built in cooling port that would normally be used anyway if the head was in a non-usdm turbo Subaru (right hand drive). Anyone can simply look this up in the shop manual for jdm vs. usdm models. And, as a point of responsibility, you should point out that the pressure differential this would create will reduce the flow to the other side of the engine. Which could raise the average running temp on that side by 1-2deg c. Which also affects how hot the turbo cartridge will run ( and thus its usable lifetime ) since it is the recipient of water flow from this exact same port in the other head.
"Reverse" cooling is where the flow from the pump goes directly into the heads, then through the blocks water jacket and out to the radiator. You should know this from your involvement in other motorsports.
And, as a suggestion, since you are an engineer, you may want to run a few numbers before getting out your cutters. I think you will find that modifying the head gaskets may only give 1-2deg c improvement ( if that ).
I really want to see your channel succeed. There are so few people showing old-school Subi-love anymore. Please take more care in your research and presentation on your videos. As it stands, by attaching your IRL professional credentials to this video, you actually make yourself look bad because you are propagating misinformation. You are also putting your current employment at risk, as more and more companies are letting go of employees when they find out that they are producing media on any of the social media platforms other than LinkedIn.
Signed, A concerned car enthusiast and TH-cam citizen.
If I have an RHD engine here in Australia would I benefit from doing this mod?
@@WildDanHibiki Want to know this too!
Correct. This is not REVERSE COOLING. This is just adding back a coolant flow that exists on twin turbo Subaru engines. (look it up)
Late reply here (BIG TIME, lol). Just wanted you to know I’m back and got some cool things unfolding on the channel. Cheers and hope you are well!!! 👊
What reverse coolant kit do you believe works best?
All the same. Make your own cost 20-25
Getadomtune.com He is the originator of the mod. He chose the diameter of the mod carefully to make the most of it. Don't just grab some fittings and throw them on. Do it right and get the results.
maxs1000rr getting your own fittings and hoses will do the same thing for much cheaper.