Throttle Body Bypass pipe

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sisplish
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Throttle Body Bypass pipe

Post by sisplish »

Hi all, I am newbie to forum and have just registered a V8 Dax Rush back in November :)

Quick and hopefully fairly straight forward question for my first post, I currently have my heater feed pipe from the inlet manifold capped off but have an 8mm pipe from the manifold(opposite side) feeding the throttle body linked back to near the pump inlet bypassing the radiator. As I have just had the car register I am venturing out in the cold and can see from the temperature gauge that the thermostat is doing its job and holding at around 88D. I am just a bit concerned that with the thermostat just on the boarder of open and shut is that I don't have enough flow through the engine.
I have a couple of options;
1) Leave as is assuming correct bypass flow through 8mm throttle body link.
2) By pass throttle body with the same setup.
3) Link heater feed to near pump inlet bypassing radiator. Problem with this is that most of the flow could bypass the radiator as the heater feed pipe is around 16mm. Also the thermostat only really has a 18mm flow hole when open. The Thermostat currently has a 3mm hole for air, this could be drilled to say 6mm?
I have read a number of threads but none saying the bypass was through the throttle body.
Any comments will be much appreciated.



DaveEFI
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Post by DaveEFI »

The coolant temperature sensor is normally on the engine side of the thermostat. If you had poor circulation within the engine, it would overheat and show on the gauge.

The heater circuit is independent of any bypass needed. On my SD1 EFI with aircon, there is a valve which shuts down the flow to the heater totally when the AC is in use.
Dave
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ChrisJC
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Post by ChrisJC »

There should be another circuit, the Thermostat Bypass circuit which is always open. It's in parallel to the heater circuit, so as Dave says, if that is shut, you still have circulation.

What inlet manifold / front cover do you have?

Chris.
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sisplish
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Post by sisplish »

Have attached a picture below to show my current setup. On the left of the photo is the heater connection capped off, after the thermostat I have a pipe direct to the radiator, no bypass from this location, Then just close to the water temp sensor is a pipe currently connected to the Throttle body on the plenum. As I have no other bypass pipe I am now considering to bypass the Throttle body plenum pipes and connect the pipe on the right side of the intake directly to near the inlet of the pump.
Current setup is Hotwire/Gems intake manifold running Megasquirt MS11 with Serpentine front cover.


Image

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ChrisJC
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Post by ChrisJC »

You are right - on that manifold there is no bypass because the heater matrix is always hot, and the temperature control is done via air flaps.

I would just connect the heater hose to the bottom radiator hose and see what that does for you.

Chris.
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sisplish
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Post by sisplish »

Guys, Thanks for comments, plan as follows:-

Disconnect throttle body pipe from manifold and cap off one side/use for bleeding any air etc. Connect Heater 16mm pipe to pipework near inlet pump and add a flow restrictor if required to make sure most water heads through thermostat when open.

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ChrisJC
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Post by ChrisJC »

sisplish wrote:Guys, Thanks for comments, plan as follows:-

Disconnect throttle body pipe from manifold and cap off one side/use for bleeding any air etc. Connect Heater 16mm pipe to pipework near inlet pump and add a flow restrictor if required to make sure most water heads through thermostat when open.
Seems reasonable to me. I doubt if you will need a restrictor, but it will be interesting to find out.

Chris.
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R/R L405 4.4 SDV8

sisplish
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Post by sisplish »

Pipework adjusted at the weekend, went out yesterday in sunshine but only 4C..Wet roads no traction!
Heater feed pipe now connected directly to bottom hose near pump inlet. throttle body pipes blocked off. Temp seemed perfect holding about 79-80d on my temp sensor which is about 10d wrong! re-sealed in 88d thermostat in housing as had slight leak from housing now fine.
I measured actual heater outlet which was 12mm compared 6mm bypass outlet so should defo have much more bypassflow. Thermostat opening hole is around 20mm
Will have to see how it behaves in the summer may need to restrict slightly.

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Post by SuperV8 »

Do you not have a bypass coming out the front of the inlet manifold?

I'm using the GEMS inlet manifold, with the heater outlet going to the heater matrix, and the thermostat bypass (can just see the blue hose to the left of the alternator) running down the side on the block and into the thermostat housing. Using a remote housing thermostat means the flow from the bypass is slowly blocked off as the temps increase so you get full flow through the rad. One mod I intent to do is to restrict/remove the heater circuit which bypasses the radiator.
Image

Tom.
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