Pontiac GTO Forum banner

1 - 20 of 25 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1 (Edited)
Like many of you, I've been looking for some affordable horse power and cold air induction has been one of the areas of some interest to me. I've checked out several of the aftermarket CAI's and have not been impressed. My major concern is that they pull air from under the hood, usually the last place to look for cold air. Additionally, many of these units are not emissions approved and they strike me as a tad pricey!

So I checked out the stock system to see if it could be the basis of a CAI. What I found was mostly good news. The air box has a large, forward facing opening, a generally smooth interior, adequate volume above and below the filter element, and a large diameter discharge opening to the MAF. I would like a larger filter but a K&N type filter would probably provide sufficent flow for most applications in the 400 to 500 HP range. The plastic MAF to throttle body pipe (MAF pipe) is a bit of a disaster in my opinion, with a reduced diameter, ribbed walls and sloppy heat welded plastic seams all combining to compromise air flow.

Conclusion #1: The MAF pipe needs to be replaced with a unit that is resistant to heat soak (plastic) and has a smooth interior with a nice transition to the throttle body. Power gains? My guess is no more than 10 and more like 3 or 4 HP.

Conclusion #2: Replace the stock filter with a K&N type filter. Power gains? Again not much, perhaps 2 to 4 HP on a good day.

Next I looked at the intake of the stock air box. Its' large opening passes through the front bulkhead and draws air from behind the left headlight. After a through inspection I concluded that the stock air box was an effective cold air system in the factory configueratioin. To confrm that this was indeed the case I did a little test. I purchased two digital indoor/outdoor thermometers. I placed the sensor for one unit (the reference temperature) on the bottom of the front bumper cap, this is where you generally like to put a ram air intake if you have that option. This placement put the unit out of the sun and in the fresh air stream as the car moved forward. I then suspended the sensor of the second unit in the center of the stock air box opening. I placed the display heads for both units on the dash and hit the road.

My results: At 55 mph with an air temperature in the low 70's the difference in temperature on both displays was less than one degree F at all times, while moving forward. At rest both readouts would climb, the reference unit always maintaining a lower temperature by 5-7 degrees F. Once in motion it only took about a minute for both displays to return to near identical readouts. The delay in temperature drop can be attributed to the so-so response time of the thermometers.

Conclusion #3: Aftermarket CAI's have little to offer the GTO.

My opinion: Current CAI's are of little value. I know that dyno results may improve (Remember dyno results on a cold air system are generally of little value because the hood is almost always open and the air flow over the vehicle is not normal because they cooling is done by external fan. Under these conditions even a really good CAI or even Ram Air Intake will often show little or no gain but track times will improve) when they are installed but there is no reason to believe, at this time, that this has anything to do with a reduction in intake air temperature. Any gains are more likely due to improved airflow through the air filter element and MAF pipe. Additionlly, most units have an open element which means that when you close the hood you are feeding your engine nice tosty preheated air, the exact opposite of the desired condition. Some have suggested that these CAI's produce power by repositioning the IAT (intake air temperature) sensor to a more desirable location. This may be the case, but such a change has nothing to do with the CAI's primary goal of delivering cool air to the throttle body. If data are available that show that relocating the IAT produces more power sign me up! I just cant see spending $200.00-$300.00 for a complete CAI when relocationg the IAT may be all that is needed.

So my plans for now are to look for a high flow MAF pipe (anybody know who has them and how much they cost?), get a K&N filter and see if I can extend the air box intake to some exterior location to create a "ram air" intake for the stock air box.


Ok folks, let's hear what you think,

Warren
 

·
Registered
Joined
·
194 Posts
I will have to agree with your three conclusions. I think the stock air box is fine and should support as much air as needed so far. I think the stock paper filter should be replaced with the k&n panel filter. Also I would replace the stock induction tube with one of the CS tubes from NZ because of the carbon fiber and the smooth inside of the tube. Good conclusions!
 

·
Registered
Joined
·
23 Posts
Discussion Starter #3
Thanks for the feedback. I've seen several people comment on the CS MAF pipe but I have yet to see a price or a web site that has any purchasing/product info. Perhaps you or some other member can help me out on this.

Thanks

Warren
 

·
Registered
Joined
·
23 Posts
Discussion Starter #5
Thanks for the info on the CS pipe, it's a nice looking unit but I think I'll try making my own. I'll post the results when it's done.
 

·
Registered
Joined
·
590 Posts
I put the K&N CAI on and like previous ones on my Fbods, I must say it makes a difference. The car lifts quicker and faster, the plenum is smooth and polished on the interior. the car gets the air from same area as oem air box.
seat of the pants says there's a little more there.

in addition to flow, remember, stock air intake boxes and entire systems are deisgned to be quiet in the cockpit. the K&N system certainly produces a throatier intake sound.

haven't dynoed yet, though. (huntin' season and all :D )
 

·
Registered
Joined
·
7 Posts
wakarr said:
Ok folks, let's hear what you think,

Warren
Thanks for sharing your views and findings... I find the Aussie sites are usually a good place to learn how "best" to gain HP at reasonable price/return ratios. http://www.ls1gto.com/forums/showthread.php?t=5949

Thus, I believe the threads on other GTO sites in the US and Australia can point you in the right direction.

The following is an image that describes where to place the hole, the site explains how to.

The following seems reasonable for a new MAF pipe. http://www.capa.com.au/ls1_induction.htm

I hope my references in this reply comply with editors wishes...

Best wishes, Bio
 

·
Registered
Joined
·
23 Posts
Discussion Starter #8
Thanks for those helpful links. I plan to start work this weekend. I'll keep you posted.

Warren
 

·
Registered
Joined
·
22 Posts
How about this type of home made inlet?

Worth 1.5 mph in the 1/8 over stock.

Ed


 

·
Registered
Joined
·
107 Posts
EDC said:
How about this type of home made inlet?

Worth 1.5 mph in the 1/8 over stock.

Ed


I did the same on both my 1995 B-bodies. In fact, almost all B-body enthusiasts do so. It really smooths out the flow from the box to the manifold, and it costs about $10, if even that much. Now all you have to do is paint it black to match and you're good to go!
 

·
Registered
Joined
·
22 Posts
SDMF Jon said:
I did the same on both my 1995 B-bodies. In fact, almost all B-body enthusiasts do so. It really smooths out the flow from the box to the manifold, and it costs about $10, if even that much. Now all you have to do is paint it black to match and you're good to go!
I'm looking into having it made in one piece and adding a cone air filter. Maybe even marketing the thing later on...

The car will more than likely be converted to speed density so I can run a new inlet pipe to where ever I want after that!

Ed
 

·
Registered
Joined
·
107 Posts
EDC said:
I'm looking into having it made in one piece and adding a cone air filter. Maybe even marketing the thing later on...
You can do that, and I don't want to stifle your ingenuity, but it's really, really simple and cheap to buy those PVC pieces from Home Depot or Lowes. A couple of elbow joints and a couple of feet of straight pipe with some PVC glue at the connections.....IMO, it's just too easy to do that instead of spending big bucks on something else.

But, a single piece will certainly look better and will save someone the "hassle" of doing it themselves. Good luck, and let us know how it goes!
:cool :cheers
 

·
Registered
Joined
·
22 Posts
SDMF Jon said:
You can do that, and I don't want to stifle your ingenuity, but it's really, really simple and cheap to buy those PVC pieces from Home Depot or Lowes. A couple of elbow joints and a couple of feet of straight pipe with some PVC glue at the connections.....IMO, it's just too easy to do that instead of spending big bucks on something else.
That's exactly what I did to make this prototype. Tough to sell it to the public though! ;)
But, a single piece will certainly look better and will save someone the "hassle" of doing it themselves. Good luck, and let us know how it goes!
:cool :cheers
Maybe carbon fibre??? :D

Ed
 

·
Registered
Joined
·
107 Posts
EDC said:
Maybe carbon fibre??? :D

Ed
Ed, carbon fiber would be ideal, of course. But it's also costly. It all depends on how much you and your potential buyers want to spend. For me, PVC may be a bit heavier, and require a more work to put it together & paint, but it's much cheaper. I dunno....like I said, everything boils down to the $ for me. Heck, I can't even afford a GTO! It's all moot to me!

*runs away crying*
 

·
Registered
Joined
·
22 Posts
SDMF Jon said:
Ed, carbon fiber would be ideal, of course. But it's also costly. It all depends on how much you and your potential buyers want to spend. For me, PVC may be a bit heavier, and require a more work to put it together & paint, but it's much cheaper. I dunno....like I said, everything boils down to the $ for me. Heck, I can't even afford a GTO! It's all moot to me!

*runs away crying*
My sister works for a local company that makes high end racing sail boats form CF so maybe they can help... :)

Ed
 

·
Registered
Joined
·
590 Posts
just got my coffee table GTO book from pontiacmall, anyway,
there's this little part i wanted to share...

" COLD AIR INDUCTION SYSTEM

The big ban theory revisited. The cooler the air, the denser the charge, the more powerful the combustion in the combustion chamber, i.e. bigger bang. That's why the GTO ducts cool air into the intake manifold from a road level inlet tucked out of sight behind the front air dam. "

I saw this "duct" when I pulled the oem air box out, and now the K&N cone hangs right over it. So these cars are more "bottom breathers" than many believe. You're not just pullin' warm air from engine compartment, as many will argue :D

I'll be putting some more holes right around this area for increased air, being aware of the dreaded hydralock. Maybe even a directional duct, like you can buy in racing supply catalogs.
 

·
Registered
Joined
·
1 Posts
I live in Minneapolis. My '04 GTO has had noticeably more power output since the weather has turned cold. Especially after dipping below freezing.
My conclusion is that:
1) The engine is breathing air heated by the radiator.
or
2) Some type of anti detonation sensor has a very conservative setting.
Either of these would offer an easy performance mod.
Anyone have thoughts?
 
1 - 20 of 25 Posts
Top