Cold Air Handling, an Hypothesis....

[Lee_Burough]

I Saw a DC Tech cold air setup the other day. I looked awesome, BUT, it eliminated the fuel cannister Something many states will not allow if you want your car to be street legal.

Looking at my TTA's air box and fuel cannister layout gave me a thought:

The TTA has an air box grabbing air from the inside of the left front fender just behind the headlight. It is an arrangement that provides cooler air and still allows fitting the fuel cannister AND the airbox in the same spot where the GN/TR fits only the fuel cannister.

Why is that significant? Because the TTA mount holds a slightly smaller fuel cannister AND an air box in the SAME space the GN/TR uses for the fuel cannister only.

Hypothosis:

Can GN/TR owners mount a cold air supply pipe AND a smaller fuel cannister in basically the same space the factory mounted the stock fuel cannister?

If yes, we could keep the fuel cannister when we add cold air plumming systems accessing the inside fender well .. ..AND still pass emissions......AND have cooler MAT's

The TTA arrangement moves the smaller fuel cannister closer to the radiator, leaving space for the air hose to course between the cannister and the windshield washer resevior.

Moving the GN/TR cannister aside and using a smaller cannister would leave a path for the air pipe to course directly to the inside of the fender wall where it will find cooler air....or, fabricators could make a mount to offset the smaller cannister and then run the cold air kit down immediately below the stock mounting position of the TR cannister, combining characteristics of the current DC and the TTA systems.

The outcome could be two important things: 1) Lower MAT's and 2) Emissions compliance in many states that require visual and dynamic emissions testing

I'm new to this hobby, maybe its been tried already, has it?
__________________

 

[TR Custom Parts]

Most of the other cold air systems out there let you keep the fuel vapor canister in the stock position, I recommend to my customers to move it over about an inch for a little more clearance. Real simple to do.

 

[Lee_Burough]

That sounds good Boosted, does your system provide access to the cooler behind the headlight as well?

 

[TR Custom Parts]

Yes it grabs the cooler air behind the headlights, unfortunately I only make kits for the 84-5 Hot Air cars and the 86-7 Intercooled TR's but nothing for the TTA's. If you have a TR also check out my site.

 

[bruce]

If you were to monitor the air temp actually in the plenum, You'd see that is really doesn't change that much. After less then even a minute of running time, it starts to warm at even a faster rate then the coolant temp..

GM cut almost too many corners on the GN powertrain, and while you might see some gains, they might not be for the reasons you think.

Just as one example.
There is what is called MAF dropout, and just say your car is just on the edge of it. So you install a Ram Air kit and the drops the gm/sec just enough to get you away from the Dropout, OK you go faster. But you didn't cure the real problem.

Just meant as thinking material.

 

[Lee_Burough]

MAF dropout

OK, I'll bite....What is MAF dropout? Why is it important?

I noticed the MAT rising 4 degrees at one point yesterday while coolant temp rose only 1 degree in the same Tlink recording....I know you hava a point here, make me/us smart on this MAF dropout, pretty please

 

[TurboDave]

Re: MAF dropout

Originally posted by lburou
OK, I'll bite....What is MAF dropout? Why is it important?

I noticed the MAT rising 4 degrees at one point yesterday while coolant temp rose only 1 degree in the same Tlink recording....I know you hava a point here, make me/us smart on this MAF dropout, pretty please

Once you get your MAF to peg at 255 for more than a few seconds (indicating significantly more air flow than 255), you'll start seeing what MAF drop out looks like, and start feeling it in some cases. But I doubt you'll actually see it on your ALDL based scan tool. Too much time lost.

 

[d0n_3d]

i flow 255+ gps constantly and i don't experience this dropout you guys are referring to? i will hit 255 on turbolink while only going 3/4 throttle...this is with the ls1 maf sensor and translator with boosted gn's cold air kit

 

[bruce]

Re: Re: MAF dropout

Originally posted by TurboDave


Once you get your MAF to peg at 255 for more than a few seconds (indicating significantly more air flow than 255), you'll start seeing what MAF drop out looks like, and start feeling it in some cases. But I doubt you'll actually see it on your ALDL based scan tool. Too much time lost.

It actually varies by prom version.
There are some variances in the different bin files.
The time period randomly varies, it might be just as the MAF hits the trip frequency/ code spot, or possibly several seconds later.

While the spikes on DS really don't look like alot, you can definetly hear the injecotor turn off. I was running some injectors on the ecm bench today, and things were intersting to say the least.

 

[Two Lane]

So, in an effort to lower air temperature in the plenum, are phenolic spacers effective?

If not, are there other practical solutions?

 

[Two Lane]

And, do the Direct Scan readings re: MAF drop-out indicate Cold Air set-ups are ineffective?

 

[scottyb]

I moved my vapor canister to the location of the original airbox, but it wasn't necessary because I had my home-made cold air kit with the canister in the original spot. I moved it because I planned to put an alcohol tank in the corner where the canister was originally.

 

[TurboDave]

Originally posted by Two Lane
And, do the Direct Scan readings re: MAF drop-out indicate Cold Air set-ups are ineffective?

Has nothing to do with manifold temps. It's a function of the math within the ECM's and the buffer overload that is experienced.

Oh BTW, no, phenolic spacers are a waste.

 

[bruce]

Originally posted by Two Lane
So, in an effort to lower air temperature in the plenum, are phenolic spacers effective?
If not, are there other practical solutions?

The spacers serve no real purpose for dropping manifold temps for the air,
HOWEVER.
They do increase the plenum volume which is a good thing.

 

[TurboDave]

Originally posted by bruce


HOWEVER.
They do increase the plenum volume which is a good thing.

On a normally aspirated car, yes. But they haven't been proven to be of ANY benefit in turbo applications where the manifold spends much/all of it's HP time at high positive pressures.

 

[bruce]

Originally posted by TurboDave


On a normally aspirated car, yes. But they haven't been proven to be of ANY benefit in turbo applications where the manifold spends much/all of it's HP time at high positive pressures.

Then why fo the sheetmetal intakes, for the GNs, go to a larger one?.

If you look at the reason for 3-6 running lean, it's about air distribution, while the Power Plate is one answer, another is seriously enlarging the Plenum volume, that also can even out the air distribution.

 

[TurboDave]

Seems to me the only cars I've seen sheet metal manifolds running on are what, 7,8 and 9 second T/R's? maybe a few 10 second rides. You know, the one's that ingest a LOT more air and fuel than our run of the mill street cars do, and need the specialty designs that sheet metal manifolds render.

 

[bruce]

Originally posted by TurboDave
Seems to me the only cars I've seen sheet metal manifolds running on are what, 7,8 and 9 second T/R's? maybe a few 10 second rides. You know, the one's that ingest a LOT more air and fuel than our run of the mill street cars do, and need the specialty designs that sheet metal manifolds render.

So the air distribution problem in the GN doesn't exist?.
OK,

 

[TurboDave]

Distribution problem, yes. Didn't say it didn't exist. My point was that a phenolic spacer (or metal for that matter) in and of its self have not been proven to be of any benefit. Adding a spacer isn't going to change the "distribution" appreciably. Just volume.
Devices that actually change the distribution (re-shaped upper plenums, or "power plates") are going to do more to cure the distribution problem.

 

[bruce]

Originally posted by TurboDave
Distribution problem, yes. Didn't say it didn't exist. My point was that a phenolic spacer (or metal for that matter) in and of its self have not been proven to be of any benefit. Adding a spacer isn't going to change the "distribution" appreciably. Just volume.
Devices that actually change the distribution (re-shaped upper plenums, or "power plates") are going to do more to cure the distribution problem.

Now, you've changed things to suit your point.
If you look back I said increasing the volume was a good thing, and didn't limit it to JUST using a spacer.
With some work you can about double the oem plenum's volume, and that does work. Which gets back to the original statement that you disagreed with. A large plenum will even out the distribution, and you don't need to be running 9s to notice it. And a simple glance at a how HAC ducting is done will clarify what the real problem is.

While a spacer alone might not make a huge difference, things add up. Rework the plenum, add a spacer, and you can make a difference. Not to confuse things, but I increased my plenum 30 CID, and then had to add 8% more fuel to get back to a given AFR. To me that would indicate, the engine was flowing more air, and needed an increase in fuel. And again, to me, I think increasing the airflow, and amount of fuel an engine consumes, maintaining a specifc AFR, would be a good thing.
YMMV