19bonestock88's 2004 Saturn "Ion Green Line" build...

[19bonestock88]

Made some more progress on the car. Hood vents are half done and some preliminary testing done. So far it’s looking promising. Today we had ambient temps in the upper fifties (not quite ideal but not bad) and I had IATs near 70F. On the flatter stretches of freeway at 60mph indicated (63-64 actual) I was holding steady between 25 and 25.5% engine load, almost 2100RPM, and instant mileage jumping around between 51 and 53mpg. I still haven’t installed all of the hood vents (which help massively with heat soak) and I’ve yet to install smooth covers on my new wheels, and I still have a splitter/front belly pan to install. I venture to say it’s coming along nicely!

[MeteorGray]

Lookin' good!

I like hood vents myself.

I'm convinced that my batteries, belts, hoses and other heat-damageable things last longer when the intense engine bay heat is allowed to escape up and out of the engine bay.

In fact, I've installed hood louvers on my Mazda, Jeep and F250. I've measured the under-hood temps, and the louvers do allow the heat to dissipate much better and faster than a solid hood top.

Relative to fuel mileage, I have found the louvers do not affect that for better or for worse. But I am (obviously) convinced the vents are well worth the effort in other ways.

For those who like to keep the engine bay warmer in wintertime, it's no problem to keep the heat in by attaching a sheet of aluminum from underneath, using the same studs that hold the vents in place on the hood.

[19bonestock88]

Related to heat dissipation, my coolant temps have been about the same as always. Switching bumpers has totally deleted any kind of upper grille opening but has made a usable lower grille opening, with the total area coming in about 10% less than my previous setup with an unblocked upper and a 80% blocked lower grille. What I am definitely noticing though, is less heat soak, manifest in lower IAT temps after brief periods of sitting. It makes sense given that one of my current vents is directly above the airbox. I drove the other day with ambient temps around 40F, and while the hood surface was ice cold, there was heat pouring out of the vents. I’m hoping that since the other vents I have marked are closer to the radiator, I’ll see a change in coolant temperature (and hopefully more drag reduction) when I finish my hood

[MeteorGray]

Unless there is a problem that causes the radiator cooling system to max out with the thermostat fully open at all times, I doubt venting the hood will make a difference in coolant temperatures. At least, they don't for me.

In my vehicles, none of which have grill blocks because in my semi-tropical climate I often need all the cooling I can get, the coolant temperatures are regulated by the thermostat at an optimal operational level. The addition of hood louvers have not changed that at all for me, and I really didn't want it to because temperatures below optimal can cause other operational difficulties, including a potential hit on fuel mileage.

[cRiPpLe_rOoStEr]

Originally Posted by MeteorGray

Unless there is a problem that causes the radiator cooling system to max out with the thermostat fully open at all times, I doubt venting the hood will make a difference in coolant temperatures. At least, they don't for me.

I'm also not so sure to which extent a vented hood would effectively enhance the cooling, even though it might occasionally lead to an easier air flow which may actually increase the heat dissipation from the cylinder head.

[19bonestock88]

Got some more progress done on the car today. Other than driving it and not being able to log efficiency due to the evap issue I have finally started on the rear aero. I started with the rear lip and passenger side filler panel from a Saab 9-3 Linear and made holes with a hole saw to help with the parachute effect until I make a full underfloor

[19bonestock88]

I’ve started the process of removing weight from the car. I know it helps mileage by almost nothing but it improves dynamic response. So far I have the carpet out and the outer sill covers/kick panels drilled to save weight. Plans are to eventually delete the headliner, airbags, air conditioning, and to have holes drilled in most of the interior panels to save as much weight as possible

[Ecky]

My interior panels weigh basically nothing, but they're definitely a source of vibration. I'd say pulling everything out, I might save maybe 10lbs tops. I've been tempted to take my interior apart and slowly reassemble, tackling vibrations one by one.

[19bonestock88]

I’m in the same boat, most of the interior panels weigh very little with a few pieces as an exception. I figure that if I could save 20lb on interior panels alone I’ll prob save 8-10 by poking all the holes but it’ll look cooler than a simple gutted interior. Longer term I’d like to find some lighter seats; the factory Recaros I swapped in are almost 50lb for each front seat. I’d like to get my car down to 2499 or less

[19bonestock88]

One of the heavier interior pieces is the glovebox. It’s not ridiculously heavy but it’s prob 3lb, and the panel in front of the passenger airbag (which I plan to take out) is heavy with paneling to direct the airbag toward the occupant. I’d say those will provide the bigger parts of my interior weight loss. I have the new glovebox drilled already