custom intake

[RacerX11]

So are you going to make adjustments, or not? At first, you kept saying you weren't going to make any changes, as MAP compenstaes for everything. Now you are saying you will be "taking care of it"?

The air/fuel gauge is a good idea. Just remember, lean is bad, rich is OK. You aren't going to hurt anything running rich (unless you run it so rich you wash down the cylinder walls and dilute the oil). With this setup, you are more likely to run it lean (like Ben said), which will burn stuff up in a hurry if you aren't careful. Burning a hole in a piston, or burning a valve is not something easily fixed.

Don't take your MAP reading from some canister or resevoir. You need to hook up all 6 vacuum lines teed together, with as little volume as possible. Running the MAP sensor off a canister used to supply vacuum to the brakes, etc. will result in very slow response, which you don't want.

Marty

[Anonymous]

Ok then when I order them I will tell them not to include the box thingy and I will rig it up myself.

Well originally I thought the MAP would be able to compensate enough. Now that I know it can't, I will get ahold of this emanage and the gauge and work from there. I also should get new injectors, but I havn't thought much about sizes and such. I will already have a aftermarket FPR, and the stock pump should do fine for now. And I may not even need to use the emanage, cuz I have a feeling that will be a bitch. And people mostly get those to adjust ignition timing for boost. SInce I don't have boost, ignition timing shouldn't be an issue.

[RacerX11]

When you order what?

You might still need the vacuum resevoir for the brakes and other vacuum accessories, just don't plumb the MAP sensor into it.

Marty

[Anonymous]

Thr throttle bodies and air horns.

I totally forgot about the brakes. Yah so I will have them include that.

God I thought I knew so much about how this motor worked, and now look, this project has gotten 100 times harder and I don't even have the throttle bodies yet.

[RacerX11]

I thought you said several weeks ago you had already ordered the 40mm TB's????

[Anonymous]

No I am ready to. I have the series number, I know all the specs I want, etc. I was going to, then this topic took flight, and I want to wait it out a little.

And I redesigned my design on CAd. Instead of pointed them straight up, I think I am going to do a crossram setup. The fronts cross the rears and they sit at an angle. The reasoning is the runner will be around 8" long, so I have some prayer of a low end. Plus the ports are almost a perfect 90*, so I do not need any turns, so no mandrel bends, which aren't cheap. If you have a spare LIM, put it against a wall, it is very close to meeting flush with the wall and floor.

[pocket-rocket]

I beleive there is also a BARO sensor in them too... or there was in my Camaro RS.

There is on our cars too. The ECM uses the MAP sensor to find out what the barometric pressure is right before you start the car.

[pocket-rocket]

Here is the important part, so pay attention: At full throttle, your manifold pressure will be at the ambient atmospheric pressure, so modifying the engine to flow more air will not result in any more fuel being added at WOT. The pressure in the intake doesn?t change at WOT before and after mods, so there is no fuel adjustment that happens. Nice try, but not how it works in the real world. A lot of factory systems tend to be tuned on the rich side, so adding minor mods will increase airflow, and lean the mixture out, resulting in better power. Once you add enough airflow, it will start to lean out and you will have to do some tuning.

Marty

Shouldn't the take care of a lean condition using the O2 sensor (if it is in good shape) to a point?

[Anonymous]

My 02 is new and working, but it is only taking readings fromt he rear bank. The muffler shop guy, who I trust his opinion, siad that wouldn't hurt it any since it measures percentages and not amounts. But with this setup, maybe....

[RacerX11]

Ben can say for sure, but I thought the O2 sensor closed-loop fuel compensatation wouldn't work at WOT. Plus, even if it did, the standard narrowband lambda sensors don't respond quick enough for full power usage. By the time the sensor detects a lean condition and compensates for it, you have already done the damage.

Marty

[dohcfiend]

ummm. that's some serious shit that custom intake. u gonna make that lumi a trailer queen? This is just a thought, but doesn't the MAF/MAP operate off of some kind of table or chart. I don't know if the ecm/pcm is programmed to compensate that kind of mod or not. if not u will not be getting the max potential ou tof your mod.
maybe u should work with an auto electronics company and come up with an independent unit or a reprogrammed ecm or something. just a thought and nothing more i am not saying i am right or wrong, it is just what came to mind when i read this thread.

[pocket-rocket]

Ben can say for sure, but I thought the O2 sensor closed-loop fuel compensatation wouldn't work at WOT. Plus, even if it did, the standard narrowband lambda sensors don't respond quick enough for full power usage. By the time the sensor detects a lean condition and compensates for it, you have already done the damage.

Marty

Yeah, I think you are right, at WOT, the O2 sensor is not used.

[Anonymous]

It is serious. I hope it will be streetable tho. It should be. I designed it using a crossram setup, so I have about 8"-12" of runner length, which should hold a lot of my low end.

Now I am using steel pipe for the runners. What size? I was thinking 1.75-2", but then I did the math. 40mm is equivalent to about 1.57", so round that to 1.625", and that is 1 5/8". But our factory ports are about 2" by 1 1/8". So I took that area, and figured out the diameter of a circle with the same area. The diameter ended up being 1.67". Now cut off about 1/4" or so becauz the ports are kinda D shaped. So both of these figures point to about 1 5/8", but that is the size of my headers. Now shouldn't my intake runners be a good 1/4" bigger than my header primaries? I was thinking if I took some porting into account that I should just use 1.75" pipe, but I want to hear what you all think before I spend blind money.

Thanks for the help!

[RacerX11]

Don't forget a proper intake runner has a taper to it to keep intake velocity up. A straight tube won't be as effective.

Marty

[Anonymous]

Don't forget a proper intake runner has a taper to it to keep intake velocity up. A straight tube won't be as effective.

Marty

Meaning I should try to curve it if possible?

I'd rather not becuz I do not want to buy any mandrel bent pipe, that shit isn't cheap. And then there would be all kinds of welds, and unlike the headers, I'd like this to look good.

Any idea on size tho?

And what would be the optimum runner lengh? I want a powerband similiar to what I have, but moreso on the high end.