Throttle Body By-Pass Value discussion
05-25-2014, 02:23 PM
#76
Bumping this for my pal 9k 
As we were just discussing in the racing forum, the likely best benefit is to block the whole thing. The hose is routed to take hot coolant from the rear iron, run it through the TB, and back around to the water pump inlet. In short, hot coolant is recirculating back around into the engine rather going to the radiator and being cooled down. The line is fairly small though so it is not a huge problem.
However, the heater core is set up the same way and is continuously recirculating hot coolant from the rear iron through the heater core and back to the water pump inlet regardless of whether the heater is on or not. This is a pretty good size line. In really hot climates it might help to have a valve to block this flow, but the system should be clean with fresh coolant before doing so. Opening it up once in a while to flush flow through might be needed. Letting it lay stagnant could create a corrosion or sludge issue, less so if you maintain the coolant well. Replacing a heater core is a major job, so don't take the mod lightly.
As we were just discussing in the racing forum, the likely best benefit is to block the whole thing. The hose is routed to take hot coolant from the rear iron, run it through the TB, and back around to the water pump inlet. In short, hot coolant is recirculating back around into the engine rather going to the radiator and being cooled down. The line is fairly small though so it is not a huge problem.
However, the heater core is set up the same way and is continuously recirculating hot coolant from the rear iron through the heater core and back to the water pump inlet regardless of whether the heater is on or not. This is a pretty good size line. In really hot climates it might help to have a valve to block this flow, but the system should be clean with fresh coolant before doing so. Opening it up once in a while to flush flow through might be needed. Letting it lay stagnant could create a corrosion or sludge issue, less so if you maintain the coolant well. Replacing a heater core is a major job, so don't take the mod lightly.
05-25-2014, 03:12 PM
#77
could you even take it one (granted more involved) step further and instead of blocking it off...run the line through a small rad? only as a solution to keeping coolant stagnant in the line while cooling it a bit before the pump?
Posted From RX8Club.com Android App
Posted From RX8Club.com Android App
05-27-2014, 04:51 PM
#79
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 240 Likes
on
110 Posts
It would slow down warmup unless you controlled it via a thermostat at some temp but certainly would increase the amount of heat that you could shed from the system.
05-27-2014, 05:44 PM
#80
SARX Legend
Thread Starter
iTrader: (46)
And to add to this, one time we installed a reman and it overheated almost instantly after a couple of minutes of idling. We had installed ne heater and coolant hoses and forgot the restrict-or in the line that goes to the AST. We installed it and all was good, I still don't understand why though.
05-27-2014, 08:01 PM
#83
And to add to this, one time we installed a reman and it overheated almost instantly after a couple of minutes of idling. We had installed ne heater and coolant hoses and forgot the restrict-or in the line that goes to the AST. We installed it and all was good, I still don't understand why though.
05-28-2014, 12:14 AM
#89
They show the one for the heater though with a part indicator. Plus it was easy to check mine right now since the engine is out and I'm working on it ...
Nada, both hoses are straight through, no restrictor between the coolant tank and either the water pump or radiator, at least on the USDM version.
Just checked all my heater hoses too. If there's a restrictor in there it must not be much of one because I can blow through them all like they are wide open.
Am I the first person to have actually ever checked? All of these particular hoses are OE factory. I've only ever changed the main large diameter radiator hoses. This may need further input from other owners.
Mine has that one, maybe this is the one Brettus is referring to? It flows from the thermostat discharge side. This hose is not an issue IMO. Seems to be the only restrictor on my car.
The only time it's ever gotten hot coolant temp was making a bunch of back-back runs on the dyno and I figured out later this was caused by the oil temp going through the roof because they had the fan shoved into the center front bumper cover opening only. I don't track or street drive much though.
.
.
Nada, both hoses are straight through, no restrictor between the coolant tank and either the water pump or radiator, at least on the USDM version.
Just checked all my heater hoses too. If there's a restrictor in there it must not be much of one because I can blow through them all like they are wide open.
Am I the first person to have actually ever checked? All of these particular hoses are OE factory. I've only ever changed the main large diameter radiator hoses. This may need further input from other owners.
Mine has that one, maybe this is the one Brettus is referring to? It flows from the thermostat discharge side. This hose is not an issue IMO. Seems to be the only restrictor on my car.
The only time it's ever gotten hot coolant temp was making a bunch of back-back runs on the dyno and I figured out later this was caused by the oil temp going through the roof because they had the fan shoved into the center front bumper cover opening only. I don't track or street drive much though.
.
.
Last edited by TeamRX8; 05-28-2014 at 12:35 AM.
05-28-2014, 12:56 AM
#91
Driving my unreliable rx8
Wasn't there a restrictor in the heater hose on early models Then it was removed around 05 and only put in to solve the miac when people complained about it? What tear is your car tema?
05-28-2014, 01:15 AM
#92
SARX Legend
Thread Starter
iTrader: (46)
I'm not 100% sure about the rear heater hose but I think mine has one there too. There is definitely one in the hose that goes to the top of the AST (15-277) and when we started the car without it, it overheated rather quickly at idle. The hose was replaced with just normal heater hose and the owner did not know the OEM one had a restrictor. So we cut the restrictor out of the OEM hose and installed and all was well. Made no sense to me why but the car has been running fine ever since.
05-28-2014, 09:53 AM
#94
05-28-2014, 12:55 PM
#97
Heh Heh Heh,
I crossed up a heater core thread with the throttle body thread. Looks like a common solution though.. I have my throttle body bypassed. Seemed like the right thing to do. I did not plug, I bypassed.
The valve approach mentioned is incredibly attractive for the heater hose. I want to look at it and the fluid routing a bit more, but it really looks interesting.
Thanks,
I crossed up a heater core thread with the throttle body thread. Looks like a common solution though.. I have my throttle body bypassed. Seemed like the right thing to do. I did not plug, I bypassed.
The valve approach mentioned is incredibly attractive for the heater hose. I want to look at it and the fluid routing a bit more, but it really looks interesting.
Thanks,
05-28-2014, 09:02 PM
#98
apparently they quit using the one in the heater hose from the factory as posted above and discussed in the thread linked below? Have never heard any noise in mine, but do use the higher viscosity Evans NPG-R waterless coolant and underdrive pullies
https://www.rx8club.com/rx-8-discuss...n-miac-181950/
couldn't find any TSB on it though ...
.
Last edited by TeamRX8; 05-28-2014 at 09:15 PM.
05-30-2014, 01:37 PM
#100
From GA RX8 Club, if the first words did not give it away.... after re-reading some of this..
Yall know and probably get tired of me talking about cooling the rotary engine.
I have tried many, many different things toward trying to get to that goal. The last "package" that I had including a different fan controller ( works VERY well) mazmart pump and thermostat for the cooler months and then adding a small secondary radiator for the really hot months--like over 90F. Those set ups have really worked well for me. Cooling is stable and within parameters. Engine still warms up normally.
Well it was a pita to reinstall the secondary cooler and clear the air out of the cooling system every year so I was thinking about a system in which i wouldnt have to be doing that.
Solution----remote fluid thermostat from Derale! $55 from summit racing. This is hooked up to the heater hose between the heater and the radiator. It allows a small amount of coolant to flow through at all times ( approx 5%), it has only 3/8 inch fittings ( the heater coolant system does need a little resistance) and it begins to open at 170F and is fully open at 200F. PERFECT. Now just install it once and leave it alone--no more summer/winter cooling systems!
Now it is sweet, spot on and this fool doesnt have to fool with it anymore!
And
So my stable year round cooling package now consists of ( and I dont think all of these items are needed)
1-Mazmart w/p and thermostat--thermostat drilled with one 1/8 inch hole ( i will not go into all those reasons)
2- flex a lite fan controller that activates BOTH ( this is important)fans at 185F
3- a very small open fin design Summit racing cooler 21x 7 mounted directly on the front bumper support ( the back side of the cooler does not have to be open to the air--if it is--ok but it doesnt have to be, but the face of the cooler needs to be in the airflow. That front bumper support is also a HUGE heat sink. Dont forget to open up your grill a little
4- derale fluid thermostat that starts opening at 170F--look it up and read the details.
5- coolant bend of water /coolant 70 W 30 C
6- oem radiator cap
7- oem radiator
8- pull the a/c condensor away from the radiator approx 1 inch this allows the fans to pull air better
9- proper radiator hoses --the biggest bottom radiator hose you can get. full supply to the water pump is critical.
Yall know and probably get tired of me talking about cooling the rotary engine.
I have tried many, many different things toward trying to get to that goal. The last "package" that I had including a different fan controller ( works VERY well) mazmart pump and thermostat for the cooler months and then adding a small secondary radiator for the really hot months--like over 90F. Those set ups have really worked well for me. Cooling is stable and within parameters. Engine still warms up normally.
Well it was a pita to reinstall the secondary cooler and clear the air out of the cooling system every year so I was thinking about a system in which i wouldnt have to be doing that.
Solution----remote fluid thermostat from Derale! $55 from summit racing. This is hooked up to the heater hose between the heater and the radiator. It allows a small amount of coolant to flow through at all times ( approx 5%), it has only 3/8 inch fittings ( the heater coolant system does need a little resistance) and it begins to open at 170F and is fully open at 200F. PERFECT. Now just install it once and leave it alone--no more summer/winter cooling systems!
Now it is sweet, spot on and this fool doesnt have to fool with it anymore!
And
So my stable year round cooling package now consists of ( and I dont think all of these items are needed)
1-Mazmart w/p and thermostat--thermostat drilled with one 1/8 inch hole ( i will not go into all those reasons)
2- flex a lite fan controller that activates BOTH ( this is important)fans at 185F
3- a very small open fin design Summit racing cooler 21x 7 mounted directly on the front bumper support ( the back side of the cooler does not have to be open to the air--if it is--ok but it doesnt have to be, but the face of the cooler needs to be in the airflow. That front bumper support is also a HUGE heat sink. Dont forget to open up your grill a little
4- derale fluid thermostat that starts opening at 170F--look it up and read the details.
5- coolant bend of water /coolant 70 W 30 C
6- oem radiator cap
7- oem radiator
8- pull the a/c condensor away from the radiator approx 1 inch this allows the fans to pull air better
9- proper radiator hoses --the biggest bottom radiator hose you can get. full supply to the water pump is critical.