So I cut up my front bumper...

[turbowop]

I can appreciate what you're trying to do here, I just think it didn't turn out aesthetically pleasing for the car. I mean...diamond plate? Srsly? I still don't see this providing any real-world gains, on the track or off. Sorry, dood.

 

In all honesty, the diamond plate wasn't exactly plan-A.

 

[broxma]

Dimension of front bumper opening - 29 x 7 (All bars cut, totally open)
Weight of one cubic foot of air - .0807
Surface area of one square foot - 144 in.
Total square foot of opening - 1.409
My personal weight this morning - 160

Everyone agree? Cool. Moving on.

1.409 x 5280 = 7439.52
7439.52 x .0807 = 600.369

Every mile you drive, your car pushes the equivalent in weight of almost 4 of me through just the front opening meant for the area taken up by the intercooler. Let's say that again. 4 human beings by weight pass through your intercooler opening every mile.

So lets say that this air dam increased the efficiency by 5%, hell I'll give you 10%.

Your IC looks to be about 20" in length. Intercoolers show a measured exponential decrease in efficiency for an increase in length past a certain efficiency. What this means is that while the first 20 inches may bring the charge air within 70% of ambient, adding another 4 inches, increasing from 20 to 24 inches in length, would only net another 10-15%. Further increases would yield less and less, the next 4" only increasing efficiency say 2-5%. This is just an example, not meant to be scientific but you can understand the principle.

Even given the 5-10% increase this air dam might have improved the efficiency, the same increase would have most likely been achieved increasing the length or efficiency of the core even given the decreasing return of doing so. In particular, increasing the real quality of the core which alone would have the most dramatic effect.

On a Subaru where airflow to the core is limited due to its mounting position and the lack of flow through the hood scoop, an idea such as this may improve things more dramatically, however a front mount configuration is in fact the most efficient setup aside from water-air cooling. No cooling system will be 100% efficient without added energy (See Laws of Thermodynamics), so your air dam idea while well intentioned, is probably not going to do anything for the car. The added weight of the diamond plate and resulting increase in resistance (See Drag) would most likely negate any improvements to the air cooling system.

/brox

 

[gtluke]

you aren't going to get any more airflow through it unless you duct the area behind it

 

[mitsuturbo]

Recently we got news that the front fascia is NLA in the USA.

Now this?

/ubbthreads/images/graemlins/bawling.gif Why? WHY?! Oh, god... please... think of the CHILDREN!

 

Wow brox! I'm impressed. You've turned this into a real science project. That's what I like about you. I'm not arguing with you, merely commenting on your post.

The core on my car 24 by 12. I managed to make the opening in the bumper 24 by 10.5.

The diamond does add turbulence, I agree with that. But the over all weight of the car decreased with this mod, because what was once a full bumper reinforcement bar is no longer.

Considering that I started with a completely uncut bumper, I feel a 5-10% increase in efficiency is way low. As for the boxing versus the already cut bumper, you're probably right.

 

[curtis]

Well the eff of the core is now probably as good as it will ever get. I figured up the area removed once and by cutting out all the slats and the center area it increased by like 50% or something. By streamlining the core the air isn't going to flow around the sides top or bottom and this is probably the first correct way ever done on here but you forgot it doesn't have to be that big due to the plates only about 40 to 50% of the frontal area is used to pass air from front to rear. /ubbthreads/images/graemlins/dunno.gif

So if you would have just cut the center out and not the top and bottom area it would have done just as good and maybe been more well excepted. Either way it did help I'm sure because around 30% of the air flow is lost because of air rolling around the sides. Maybe a shot of matte black on the diamond plate will change the looks of things.

This will always be a big debate if it helps or not just like the debate over top to bottom flow IC compared to side to side intercoolers. Frontal areas being the same a top to bottom will flow more due to the amount of turbulators in the core.

 

[broxma]

I'm just saying that there is an immense amount of air going through it already and such a system as realized is somewhat unnecessary. In all fairness, I have a way of conclusively and inexpensively determining the usefulness of your air dam. Just get two Extech mutlimeters with temp probes, connect one hot side and one cold with the dam on and off. I would estimate the real difference would fall into margin of error or only just a few percent different.

While efficiency is a statistic which can be objectively measured, and on an all out race car where efficiency in 10ths of a percent can make a difference between winning and losing, on a street car, we take some liberty in knowing simply that setup "A" is better than setup "B" without having to be at top efficiency. Let's look at it without taking aesthetics into account. Even if you realized a drop in cold side temps of 20 degrees, you may see a real increase in power of 2 or 3%, maybe. Now factor in aesthetics. Even in your own opinion, never mind the opinions of others, are you pleased enough with the appearance of the thing to justify the 2-3% increase(Possibly) in power? 2-3% falls within the margin of error of even the best dynos and would never be the difference in any competition unless you had two Micheal Schumacher clones behind the wheels of identical cars.

To put it into perspective, a single 90 degree bend in the intercooler pipe does more to detract from the efficiency of the IC system than the air dam could ever replace even under perfect conditions. Think about that. One bend, just the one at the throttle body, negates more in power percentage wise than the entire duct system could ever recover.

It's a nice idea, and under certain applications I can see function. It has already been mentioned that without ducting behind the core it is really a mute point and I am inclined to agree. Getting the air into the core is fine, but as my math demonstrated, flow across the core really isn't a problem. Efficiently getting away from the core from behind would be more of a concern for me.

/brox

 

[Hertz]

Quoting curtis:
By streamlining the core the air isn't going to flow around the sides top or bottom and this is probably the first correct way ever done on here



One Lap car.

This method is detailed a little bit in "Forced Induction Performance Tuning A Practical Guide to Supercharging and Turbocharging" by A. Bell. There's some good science backing the use of cowls and such...

I can't find any book that says performance mods need to pretty, but I'll throw my hat in the ring here... looks like some solid work, I think the drawback is it is so visually interrupting. You could have excluded the cowl and got the same responses here.

 

[broxma]

And I agree. I have that book in PDF which is where I get my energy loss figures for certain bends.

The question here is very much one of taste, but even given taste, is it really necessary? I think a similar objective could have been accomplished by just blocking off the passages to the sides, rather than building what appears to be a rather heavy contraption. Objectively, air will take the path of least resistance and given the option of IC restriction or an opening just to the side, it will back up and go sidewards. Given no sidewards option, it would be forced through the core without the use of such an elaborate mechanism.

Good book BTW.

/brox

 

Thanks to all who recognized the functionality aspect here. I realized from the very first post that aesthetically the response would be mixed. I DIDN'T expect that Delta Female would get her panties in such a twist over this, however. I get that everyone is entitled to their opinion, and it admittedly didn't turn out exactly like I envisioned. And the diamond plate wasn't my first choice. But I still think it looks good.

As to your query on weight broxma, this whole deal is actually quite light. It is assembled entirely of aluminum, and I'd estimate the weight at between 2 and 4 lbs. It is comprised of .063" thick aluminum DP, .063" thick aluminum angle, and aluminum rivets. In retrospect I should've used .125" thick DP, as the top panel has too much flex in it.

I know that some of you feel that I'm simply destroying a very loved, very rare car. I can understand that sentiment, but I also don't feel that my version is restoration friendly. It has been abused in its lifetime, and I feel that this particular chassis is better suited for modification. When I bought the car in 2005, I paid $300.00 bucks for it, and it was probably worth $250.00. If you had about 6 or 8 grand you could probably bring the interior/exterior back to near perfect. And that doesn't include any hidden rust that would need to be repaired. I would rather enjoy that money other ways.

 

[SmoothCustomer]

Who cares, screw the usdm bumper anyways.

 

[belize1334]

If it were me I'd have used the shape of the existing passage and funneled it into the frontal area of the FMIC. But, to each their own. For supposedly cherishing the exterior of these cars practically everyone cuts the front bumper so I'm not gonna throw stones over how you choose to do it.

 

Here's how I'd look @ mods. Let's say there's a prize at the end of the day, is the the 5% gain you're going to get from the mod worth it? Is it going to give you an edge over your competition? While everyone mods their car to their taste, I gotta say damn!!! That looks really bad!! It doesn't flow with any of the lines of the car.

Those guys drifting are in competition so there's a prize @ the end of the day. Hence the function over form is the ultimate goal in that application.

 

[jcgalntvr4-244]

Buy a JDM front bumper cut the middle out ... fixed .... have a nice day /ubbthreads/images/graemlins/grin.gif

 

Quoting Garfield Wright:
It doesn't flow with any of the lines of the car.




Now that's not true. The top of the box runs perfectly along, umm, where the chrome strip, well, used to be. And the sides, umm, they uhh, well you know, they, seem to, uhh yeah. You're right.

But that was never the point. I would like to say that after spending a day with it and reviewing the pics I took of it, I feel that I took the pics close range in an effort to focus on the mod itself and not the "mod on the car". I don't think the pics do it true justice, although other pics likely wouldn't change any minds.

 

[SmoothCustomer]

Quoting jcgalntvr4-244:
Buy a JDM front bumper cut the middle out ... fixed .... have a nice day /ubbthreads/images/graemlins/grin.gif



Way rather see him hack up a usdm bumper than a jdm one.

 

^^^Yeah I'm not sure I could do that either.

 

[RedTwo]

Quoting SmoothCustomer:
Eh it will look better black. You don't like it? You should see what the s12 guys do. Well I looked for you, and I couldn't find the picture I was looking for, but imagine this only it's cut all the way to the bottom of the bumper.

That's basically how my I/C looks, other than sitting higher into the grill...
Not my choice of material but and interesting idea. I would have ventured into 'flaring' the surrounds more at an angle (around 30-45*) to the i/c face to 'dirve' more air into the core, or at least look like that's what it will do /ubbthreads/images/graemlins/laugh.gif Kinda like the Evo X has going on.

 

[jcgalntvr4-244]

Quoting SmoothCustomer:
Quoting jcgalntvr4-244:
Buy a JDM front bumper cut the middle out ... fixed .... have a nice day /ubbthreads/images/graemlins/grin.gif



Way rather see him hack up a usdm bumper than a jdm one.



Why not .... the JDM fronts are so much more avail than the USDM bumper... /ubbthreads/images/graemlins/dunno.gif