dhpro

iTrader: (3)

A few engine bay questions:
1. Why is the hood sealed? Where is the air being directed - I'll assume out the bottom? Can I further assume that the sealed hood is deigned to improve the rad & heat exchanger efficiency?
If thats the case:
2. What happens when a hood like Spectre's is installed with heat extractors, that will basically alter the air flow dynamics by sucking air out the top front? Theoretically, this sounds proper as it wud drag all the incoming air thru and up across the cooling fins? If those fender vents are functional, wouldnt it imply underhood temps/airflow was an issue - nothing is done for nothing IMO.
3. The plactic shroud/engine cover...wouldnt this only contribute to underhood temps? The blower must only have to work harder to stay cool with all that heat trapped under it?
4. Air intake: Is the OEM design with the rubber ribbed portion on purpose? Is this to slow down the air and create turbulence before entering the TB? If so, why? We've all seen the startling results from even this minor mod
These might seem like minor issues, but as all u guys finish up the major mods and start dialing in the ponies, the incremental power and efficiencies become more important. GM engineers spent millions on these small elements and I doubt much was left to chance. An engine cover like ours isnt cheap, and seems expensive for aesthetics alone as an example, and neither are the 2 little cones on the intake tube before the TB...

aurora40

iTrader: (1)

1) I believe so. If you look at the engine bays of most all modern cars, they are sealed everywhere so that all airflow has to come through the radiator.

2) Those fender vents are purely cosmetic. And who knows what happens with an aftermarket hood. Presumably in the middle of the hood is a low-pressure area, so it would pull air through from the engine bay.

3) Those shrouds are generally for noise abatement, as well as cosmetics. Take it off and see the difference. On my V1, you can hear a lot more injector ticking with it off. GM doesn't just design a car for maximum power, it also has to meet other reasonable criteria. The blower can't work harder to stay cool, FYI. And most of the heat should be removed via the intercooler/heat exchanger, not dispersed through the case. Though part of the intercooler assembly is exposed even with the cover on.

4) Those ribbed designs are generally because the intake box is rigidly mounted, but the engine is not. Open the hood and have someone stab the gas pedal. The engine moves, and things like the intake and exhaust need to be able to accomodate that. As far as airflow, air flows through the center. I doubt the ribbing has much effect on the airflow. I assume your comment about the improvements was sarcastic because there is little gain when replacing it?

dhpro

iTrader: (3)

I was referring more to how the air flows thru the bay and out, than how it gets in actually...

The front lip, its position on the hood fore/aft and the hieght is actually what determines the amount of low pressure...its never usually by chance but design and a question I'll be asking Spectre (ie: how many CFM and how does the drip tray effect that - 1/16th more spacing can make huge diff I discovered on my truck)

I just intrinsically have a prob with these cosmetics...anything that traps heat over the blower cant help...

I'd guess there's some truth in what ur saying about the flex of the hose, but there are plenty of flow dynamics that Im sure played a part...why else have those 2 cones sticking off it? Trucks also had some whacky shapes and it turned out to be designed to slow the air intake charge and create less turbulence as it hit the TB. Also, the aftermrkt hoses tend to be metal/alum and that gets much hotter than plastic, heating the charge and reducing power. I ASK ALL THESE QUESTIONS AS THE MOST IMPORTANT THING FOR MAKING POWER ON A BOOSTED MOTOR IS A COOL AIR CHARGE...reducing underhood temps can add as much as 10rwhp if its big enuf change and that can help win races or at least increase life of parts! So ceramic coated headers would be a must as well...

scatillac

iTrader: (12)

The coil output could be influenced also as retained heat would tend to increase coil internal resistance.

Some of the aftermarket "valve covers" that hide the coils would have this effect also.

With that said, I'm sure the GM engineers designed in some compensating heat tolerance, as long as the heat remains in the ball park of the OEM design.

I run mine without the cover and trade off some heat decrease for a bit of valve train noise.

vmapper

iTrader: (8)

wacky shapes are usually intake silencers. (for most cars, especially 4 bangers) the intake will generate an awful sound if not silenced.

aurora40

iTrader: (1)

That is probably a helmholtz resonator, to reduce intake noise vs any kind of flow improver.

Also, if you think aftermarket parts like vented hoods are all made with highly calculated decisions vs just looking cool or sounding good, you probably haven't bought very many aftermarket parts...

dhpro

iTrader: (3)

Haha...Ive spent enuf that I shud have every aftermrkt part there is but I'd guess there's still a few I missed...but I've also broken most as well...here's my build thread
http://s167.photobucket.com/albums/u138/dhpro/?start=0