Throttle coolant block off.

[rhipsher]

It works great in the summer time. But when it starts getting into the 30's not so well. When it gets cold and the aluminum throttle body contracts it causes the butterfly plates to stay open. Get tired of idling at 4000rpm's at the light. Unblocked it and when the hot coolant makes its way back into the throttle body it works like a charm. Luckily or unluckily it doesnt stay cold very long in Texas before that "fry an egg on the sidewalk heat" makes it's way back. I'm going to put a summer/winter valve in line.

[Paul Workman]

Originally Posted by rhipsher

It works great in the summer time. But when it starts getting into the 30's not so well. When it gets cold and the aluminum throttle body contracts it causes the butterfly plates to stay open. Get tired of idling at 4000rpm's at the light. Unblocked it and when the hot coolant makes its way back into the throttle body it works like a charm. Luckily or unluckily it doesnt stay cold very long in Texas before that "fry an egg on the sidewalk heat" makes it's way back. I'm going to put a summer/winter valve in line.

Hmmmm.... I'm not having that problem, and I have installed the plugs in the IHs and capped off the coolant line that loops thru the TB from the passenger side. Starts, idles, and runs just fine...28 degrees...no coolant in the TB. Having this discussion w/ Marc H, he and I agreed that once the engine fires, and runs for just a little while, there is plenty of heat under the hood to prevent frosting.

And, after all, these cars were taken to Canada in the dead of winter, something like -30 or -40F, if I recall, and fired them up. At the moment the engines fired, the coolant would be at ambient temp, or waaay below zero. There was no discussion about them having issues like you describe, FWIW.

My point is, if your throttle plates are sticking at +30F, then something needs to be adjusted, methinks. But, just to be sure, I'll fire her up (temps in the low 20s now) and let you know how it goes.

P.

[rhipsher]

Yes my dear Workman! But you've also got to remember I have those 3/8 thick finalic plenum spacers and even after hours of driving my plenum is only luke warm to the touch. And my throttle body is cold to the touch. Those things really work to keep the top end cool. As soon as I unblocked it the throttle body was very warm to the touch and my butterfly valves worked great. Makes perfect sense. Of course iknew that's what the problem was. Just kept forgetting to unblock it.

[xlr8nflorida]

Originally Posted by rhipsher

Yes my dear Workman! But you've also got to remember I have those 3/8 thick finalic plenum spacers and even after hours of driving my plenum is only luke warm to the touch. And my throttle body is cold to the touch. Those things really work to keep the top end cool. As soon as I unblocked it the throttle body was very warm to the touch and my butterfly valves worked great. Makes perfect sense. Of course iknew that's what the problem was. Just kept forgetting to unblock it.

Are those spacers to keep motor cooler and not lose HP due to heat soak?

I can't remember who sold those? Do they work?

[rhipsher]

The plenum spacers take the place of the brass plugs cuz they totally block coolant from entering the plenum from the injector housings. So by unblocking the drivers side coolant hose it only allows coolant to flow to the throttle body and back hence keeping the throttle body warm and freely working. If you take a 1.00 piece of aluminum and measure it then hold it tight in your hand for a minute the heat in your hand will cause it to expand .001 of an inch. And when your talking 150 degrees irt will expand even more. Carter will back me up on that so its not unreasonable to see how going from a 98 degree day to a 30 degree day that the aluminum contracting could cause the plates to stick open and not close all the way. I know because I just proved it today by allowing coolant back into the throttle body and that was the end all be all of the problem. Sometimes its just that untechnical.

[carter200]

Rick is very correct on his explaination. Replacing the OEM throttle body plate with my billet plate is worth up to 50hp. The spacers Rick mentioned are a tried and true way to keep heat soak from the plenum.

Rick, it's getting cold here so how about sending some of your heat my way.

[USAFPILOT]

what plate are we talking about that can get you 50HP? Are you serious?

[Paul Workman]

Originally Posted by rhipsher

Yes my dear Workman! But you've also got to remember I have those 3/8 thick finalic plenum spacers and even after hours of driving my plenum is only luke warm to the touch. And my throttle body is cold to the touch. Those things really work to keep the top end cool. As soon as I unblocked it the throttle body was very warm to the touch and my butterfly valves worked great. Makes perfect sense. Of course iknew that's what the problem was. Just kept forgetting to unblock it.

A new wrinkle...In your OP there was no mention of thermal spacers. But, at the moment you first fire it up after a 30 degree soak, the coolant will be close to 30 degrees too, and if, as you say, the problem is binding of the throttle plates due to the cold (not saying your TB isn't doing what it obviously IS), are the plates bound up upon start up??

Again, I refer to the development documentation in "Heart of the Beast" where these LT5s were cranked after cold soaking in temps at least 60 degrees colder than your +30 degree experience...and there was no mention of sticking throttle plates. And, like the HOTB report, I'm not having the problem - even running the Z in the teens (temperature, degrees F)

"I'm just sayin'"...Somethin' ain't raht 'bout your stickin' plates. Temp might be the ingredient that points it out, but if your one example proves removing the bypass will prevent it, then my one example proves it isn't necessary and we have a conundrum.

Anyone else with a bypassed TB having idle issues - with or without a thermal isolator?

P.

[Paul Workman]

Originally Posted by carter200

Rick is very correct on his explaination. Replacing the OEM throttle body plate with my billet plate is worth up to 50hp. The spacers Rick mentioned are a tried and true way to keep heat soak from the plenum.

Rick, it's getting cold here so how about sending some of your heat my way.

Using a relative hp vs. air temp(only) calculator, for a 400 hp motor there is a 56 hp difference for intake air variance between 110 degrees and 30 degrees ambient air temp (pressure fixed at 30"Hg and humidity fixed at 50%) Not to get OT, but at WOT I'll wager with or without the spacer the difference in air temp entering from the outside until it enters the IHs is nowhere near the 80 degrees it would take (according to the calculator) to make a 50+ hp change due to intake air temp. I'm not arguing that air temp doesn't make a difference to hp. But, I'm dubious that the spacer in question can directly or indirectly affect intake air temp - especially at WOT - to the extent as to make anywhere close to the 50 hp difference. JMO.

P.

[rhipsher]

Paul it doesn't happen on start up. Only after you push the gas peddle. And im willing to bet that the cars you mention that were started in -60 degrees didn't have the throttle coolant blocked off either so it would of never of happened to them.