Throttle body coolant routing bypass - LotusTalk - The Lotus Cars Community
 
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post #1 of 5 (permalink) Old 02-22-2015, 04:23 AM Thread Starter
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Throttle body coolant routing bypass

Is there a performance advantage to bypassing or plugging the coolant pathway through the throttle body? My Exige sees below freezing temps so would blocking it cause any problems? My dearly departed Elise has a vf2 sc'er that was bypassed, but i don't know if this had any negative impact on reliabilty or idling issued. The vf2 tune had a high idle that was sometimes erratic.

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2008 Exige S240 ST
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post #2 of 5 (permalink) Old 02-22-2015, 05:34 AM
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Passing coolant through the throttle body is there for cold start emissions reasons, and throttle body sticking at freezing temperatures.

I'm not aware if there's any performance benefit, but I guess someone more knowledgeable should shed light on the matter...

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post #3 of 5 (permalink) Old 02-22-2015, 06:50 AM
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The big problem is this: at near freezing temps and high humidity (doesn't have to be at or below freezing), the pressure drop that results from a low throttle angle causes the temp to drop. This can create icing that is especially dangerous for cable throttle cars. Electric throttles can be less prone to sticking open and sometimes even have a de-icing mode where they will slam shut and break up ice. I have no idea if Lotus/Toyota use that on these cars.

I really don't think the air temps go down any measurable amount when you block the coolant lines, so I wouldn't bother. Now, my '05 Elise has the coolant lines bypassed, so the biggest benefit is that I don't have to fight coolant if I pull the throttle off. I've had to do that a few times, so that's been nice.

Lastly, the throttle doesn't have the chance to transfer much heat to the air - no fins and a fairly small surface area. The de-icing works because the ice won't form on the bore, but I the heat transfer to air can't be that noticeable. I'd leave it alone over the winter and maybe do a before and after over the summer and measure the temps.


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post #4 of 5 (permalink) Old 02-22-2015, 08:41 AM Thread Starter
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I had no plans to plug the coolant routing in the TB.
I was just curious because Vision Function install instructions
calls to plug the holes.

If the car is only driven in hot, arid climates it must not be an issue
to plug the coolant conduits.

Thanks

2006 Elise ST (someone else has it now . . . )
2008 Exige S240 ST
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post #5 of 5 (permalink) Old 02-23-2015, 05:16 AM
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Quote:
Originally Posted by sleepe View Post
I had no plans to plug the coolant routing in the TB.
I was just curious because Vision Function install instructions
calls to plug the holes.

If the car is only driven in hot, arid climates it must not be an issue
to plug the coolant conduits.

Thanks
no reason to plug the holes as long as the coolant is drained out of the TB sufficiently...

go ahead & bypass it if you're going to be digging around anyways, you might see a slight increase on a dyno (maybe 1-2hp tops at op. temp), but probably not enough to feel it in your seat... I plan on doing the same thing at some point soon myself just because i'd rather not have my TB heatsoaked

there aren't any drawbacks if you plan on driving in 'sane temperatures' aka above Siberian winter weather

'05 ST Elise: DHP exhaust, Quantum Zero's, Forge MS radiator, s111 v3 eliminator, s111 DSbrace, ce28n, ic7 dash...

Last edited by driftwood; 02-23-2015 at 05:24 AM.
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