[Fot] Collective wisdom

[JS Performance Motoring, LLC]

An overflow tank does not flow.
A header tank or surge tank does flow, and helps burp any steam or air
pockets that are trapped in the engine.

Two different approaches.  I prefer the latter, but many are successfully
running the simpler overflow tank setup.


Jason Sukey
JS Performance Motoring, LLC
440.984.7720
jason at jsperformancemotoring.com
www.jspmparts.com
https://www.facebook.com/JSPerformanceMotoring/


On Tue, Jan 20, 2026 at 9:12 PM Scott Janzen via Fot <fot at autox.team.net>
wrote:

> I’ve never understood overflow tanks to need “flow”. Plz correct me if I’m
> wrong, but i thought they were there just to provide for the expansion and
> contraction of coolant when heated, etc
> Sent from my iPhone
>
> On Jan 20, 2026, at 6:31 PM, vfracing--- via Fot <fot at autox.team.net>
> wrote:
>
> 
> Chuck;
>
> That heater core port on the back of the head provides flow to an
> otherwise blind spot in the head over an exhaust valve.  On a race car
> without flow through that port it could lead to early exhaust valve
> failure.  The best way to ensure flow is to plumb it to the intake side of
> the water pump, set up as if there were a heater installed.  We control the
> flow by using a 5/16 line, providing some flow but not overly bypassing
> anything.
>
>  Note that blocking that flow on a street-driven engine is OK as the
> exhaust valve is not overly stressed during street driving compared to what
> we do on-track!
>
> Hope this helps.
>
> Phil
>
>
>
> On Tuesday, January 20, 2026 at 04:16:51 PM EST, Chuck Gee via Fot <
> fot at autox.team.net> wrote:
>
>
> Hello all,
>
> In an effort to constantly improve the car, I’ve been looking at the
> cooling system on my TR4.  It currently has a header tank mounted to the
> firewall that functions as the high spot in the system.  This tank feeds
> the top of the radiator but doesn’t really circulate during operation.
> I’ve been thinking of plumbing the feed off of the back of the head into
> the top of the tank so that it circulates.
>
> Normally this rear head feed is plumbed to the back of the water pump.  In
> an exercise of overthinking, I’m not sure if there will be sufficient
> circulation since the tank is plumbed to the radiator.  Does it matter?
> What is the collective wisdom?
>
> Here are some pictures to help illustrate.
>
> Thanks,
>
> Chuck
>
>
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