How does a Grill Block help with engine warmup?

[wmjinman]

Originally Posted by t vago

Good points, all. I do not remember reading about any "optimum" temperature, as such, but pre-ignition / detonation are things to steer away from.

Preventing overly hot temperatures was one reason I went with a heater core-based heater, as opposed to an exhaust manifold-based heater. It'd be near-impossible to get 300 F out of coolant (and if you're getting that high a temperature out of coolant, you've got other issues...) Another reason was that it was easier to route coolant hoses than it was to route air hoses.

As for the actual temperature? Your guess is as good as mine. I do know that my truck seems to love 130 F as its intake temperature. I would go higher, except that might start wandering into pre-ignition / detonation territory.

Yeah, I think excessive intake air temperature is why they started putting intercoolers on turbos. Good to know yours runs well at 130, though. I'll move my target range's upper limit to there for my testing.

And your heater core idea is probably really good for cruising with a warm engine, but if your goal includes faster warmups, the benefit of warm intake air wouldn't start until AFTER the engine was already warm enough to have hot coolant in that heater core, would it?

And at the risk of being a kill-joy, if I understand right, keeping the engine nice & toasty even at low power levels, is one of our goals, right? So wouldn't the heater core air heater be undermining that effort a little? But the exhaust's heat will always be there, though, and isn't going to cool the engine down by having some heat sucked off it.

[t vago]

Originally Posted by wmjinman

Yeah, I think excessive intake air temperature is why they started putting intercoolers on turbos. Good to know yours runs well at 130, though. I'll move my target range's upper limit to there for my testing.

You reminded me... I still have these other books, from when I was interested in turbos: Forced Induction Performance Tuning, by A Graham Bell; Turbochargers, by Hugh Macinnes; Maximum Boost, by Corky Bell; and Supercharging, Turbocharging and Nitrous Oxide Performance, by Earl Davis and Diane Davis.

All of these books mention intercooling primarily as a method of cramming even more charge into the cylinders. The use of intercoolers is as a method of detonation control was mentioned as a secondary purpose (even if still important), because intake temperatures will rise as a consequence of being compressed by the boost device. The books note that detonation / pre-ignition becomes a concern when intake temperatures are well above ambient temperature, though (like around 200 F above ambient). Further, any boosted application could benefit from using an intercooler, it would seem. For instance, A. Graham Bell mentioned that even otherwise stock cars with mild levels of boost (as with an aftermarket turbo kit) can benefit from an intercooler, since he found that their stock ignition and cam settings would not need any adjustment due to boost.

This tells me that a 60 F rise in temperature is probably nothing to worry about for our warm-air intake ideas, but anything above that might merit a little bit of caution.

Originally Posted by wmjinman

And your heater core idea is probably really good for cruising with a warm engine, but if your goal includes faster warmups, the benefit of warm intake air wouldn't start until AFTER the engine was already warm enough to have hot coolant in that heater core, would it?

That is true. However, the engine starts heating up its coolant about as soon as it's started, and I have noticed decreased warm-up distances (which would translate into reduced warm-up times).

For instance, on my daily commute, I've taken the below measurements. The distances are approximate due to their being landmark distances from my house, but they do serve to point out that warm-up times are significantly reduced.

.	Stock	With WAI
Needle moves off bottom	0.9 miles	0.7 miles
UltraGauge reports 190 F	5.5 miles	3.9 miles

Using either coolant or exhaust heat, raising the intake temperature will also raise the combustion temperature, and will raise the exhaust temperature. Raising the temperatures in this fashion will raise the rate of heat transfer into the engine block, which will decrease warm-up times.

Originally Posted by wmjinman

And at the risk of being a kill-joy, if I understand right, keeping the engine nice & toasty even at low power levels, is one of our goals, right? So wouldn't the heater core air heater be undermining that effort a little? But the exhaust's heat will always be there, though, and isn't going to cool the engine down by having some heat sucked off it.

You could say the exact same thing with using the heater at full blast on an idling car. Since it's somehow able to keep operating temperature even at idle, I'd say there was still some available waste heat from the coolant to be used, especially considering that the idling engine does not suck in anywhere near as much air as that heater at full blast.

[wmjinman]

Good points. Actually, I have the Hugh McInnis book, too!! And by using a heater core, at least you don't have to wait as long for warmup as if you used the main radiator.

A few times when I had the heater going full blast, I was wondering if my wimpy-ness was costing me MPG. It probably was. :-/

[Miller88]

The grille blocks on my Focus definitely help with warm up times. NOT because they are blocking the radiator, because it's not air moving past the engine block.

I hit the highway quick in the mornings. Running at 55 there's going to be a good amount of air running through the radiator (which isn't flowing any coolant since the coolant is cold) and past the engine block. Aluminum blocks don't hold heat as well as cast iron. I suspect that's why.

Makes a HUGE difference on the focus. Almost no difference on the Cherokee.