Any reason why I would need the coolant hose to the throttle body? Car doesn't get driven in winter. Have my blower off to do coupler (amongst some other things), and would rather just cap it off instead of reinstalling the hose that runs under the blower. 2010 XKR 5.0

 

Throttle body coolant/heat hoses have been around for a long time. They are designed to "fix" a problem which doesn't really exist with modern autos - throttle body blade icing. Proponents of GM motors have been removing these hoses for at least 20 years with no ill effect, and maybe a slight hp gain. I removed mine on my '07 XK about four years ago - no problems and no issues.

 

This is a common mod on the lt1 & l98 engined GM cars from the 90s. Here's a link that shows a 6 horsepower gain on a dyno with a 1996 trans am. 6hp from a simple mod like this would definitely be worthwhile. The motor tested is certainly different than the XK motor.....but it would be interesting if someone could do a before and after dyno test with this done on a xkr….
Modifications #8

 

I wouldn't for quite a few reasons.

 

Thanks for the responses guys. I think I'm going to go ahead and delete this. It's one less thing that could potentially leak (requiring supercharger removal to fix).

unfortunately I won't be able to do a before/after dyno. Car is already torn apart due to cylinder #7 misfire and supercharger coupler rattle. I'm going to make another thread about all of that, as well as post some pics of what the carbon buildup on my intake valves looks like at 75k miles. A catch cam will also be a plan of mine to install.


ranchero, can you list a couple of your reasons? Resale isn't one for me, as I plan on keeping this car, and it's only my summer weekend driver.

 

I'm not sure on the 5.0's but on the 4.2's with EGR the hoses to the TB actually cool the exhaust gasses being injected into the intake tract. For some reason they chose an @ 16" direct route from the back of the RH exhaust manifold and a @ 72" (6') routing from the front of the LH exhaust manifold back by the transmission and then up to the TB. To me there was a lot of engineering involved with that decision process. But again, it may not apply on a 5.0 with the front mount TB.

Another reason is temp balance and even though you are not driving it in freezing conditions, the pressure different across the throttle plate may hit the freeze point at certain above freezing temps and various humidity conditions.

Finally without completely understanding the cooling loop strategy you may be shutting off a vital flow that is a primary bypass when the T-stat is closed. Small block Ford will run the risk of flash steaming at the cylinders without the bypass working. 5.0 mustangs (Foxes) actually put a 3/16" restriction port in the heater hose so the engine would warm up quicker because that passage allowed flow through the radiator to keep the engine from warming up.

I guess my advice is to fully know and understand why something was done before deciding it was a single purpose design and no longer needed. Worst case would be you ripping the hoses out and the cooling system not working correctly and then pulling the blower back off to install them. PITA. At the least if you are concerned, replace them now. Age waits for no cooling system part.

 

Good information, thank you. The hose is rubber, and I think that it would be easy enough to re-route it so it's not under the blower in the event that it is a necessary part. In stock form with the sound symposer at the the back of the engine this hose is almost impossible to reach, but since mine has been deleted I can get back there fairly easy.

For now, I'm leaning towards deleting that hose. It will be a few weeks until its all back together, I'm researching where I can send the blower off to get it it ported/polished right now.

 

All this deletion/mod does is disconnect the coolant/heat to the throttle body - nothing more. All other functions in the coolant circuit remain fully intact - coolant continues to flow, just not through the throttle body. EX/PZ.

 

Yep and one less hose to worry about leaking, a tidier engine bay, and possibly lower IAT's.

 

Your IATs won't change due to the thermal conductivity from the head, through your lower plenums and into the lid which your intercoolers are bolted to.

There's so many other hot things between the tb and combustion chamber that it won't matter.

 

Disagree with Mandrake. In my posts I was purposely vague about intake temp changes, simply because I have never measured temp change. BUT, it does make a difference and dyno tests have consistently demonstrated this. My source was TPIS of Chaska, MN has both an engine and chassis dyno. They tested this extensively on GM LS motors, and always saw a power gain. TPIS has sold thousands of hose connectors for this mod. The only explanation for increased hp is decreased intake air temp. I think every little bit to decrease intake air temp, especially on supercharged Jaguars, helps. Most of all, it is "free horsepower" with absolutely no drawbacks/downsides.

 

I think it will help, but probably not enough to notice.

I am also curious as to why the water pump discharge has a small hose going into a tee that ties into the throttle body coolant outlet hose. That is the hose that runs under the S/C to the cooling return manifold at the rear of the engine. I'll get a picture of it tonight. I broke mine at the water pump, pump is getting replaced anyway so I just need to figure out how to blank it off at the pump on the new one.

 

You obviously have no idea how this system works or spent any time at all in the 5.0 X150 service manual. Took me about three minutes in the .PDF to realize it's a damn foolish plan of action...

 

So how much are you asking for to show him the right way.

 

I'd rather make him a fisherman than give him a fish. I deal with this stuff at work so no drama.

#notmymotorthatgetsmelted

 

I have done this mod for a short period of time. After checking temps of before and after on the T elbow I then came to realization that potentially on a supercharged car where top of the engine gets very hot, the coolant flow might actually be lowering the temps below what throttle body would be at without the coolant flow. To lower intake temperature on our cars , the best mod from my research is killer chiller, then there is methenol injection and there is an option to separate the coolant loop to intercoolers only and add an additional radiator and fan to this loop.

 

Anybody have a flow chart for the 5.0 S/C cooling system?

 

 

Thank you for the diagram...I have been doing some "fishing" and looking at the shop manuals, going to go ahead and re-route this line and bypass the TB.

Thanks to everyone who contributed without arrogance. This place is for learning as well as teaching, so I'll let everyone know if I "melt my motor"

 

I recently did the throttle body by-pass on my new-to-me '13 XK. The by-pass line continues underneath the intake manifold. This coolant line is the only coolant line beneath the intake manifold on my N/A 5.0 XK. The OEM coolant line is a thin-wall molded line with several curves. I replaced the oem line with Gates 3270, which is 7.9mm or 5/16" available at NAPA for $1.79/ft., which is far more robust than the oem.