custom intake

[93vinx]

ok i'm loking into making a custom intake, but i'm not sure if i wanna use map, i was thinking about converting to maf but wasn't sure what was involved, searched posts but nothing was supportive, i already figuired out the iac and tps but i'm not sure how map would respond would it throw the signal off with so much more air?

[Anonymous]

Mine hates me, but I still love it. Sometimes.

I am also going into a custom manifold setup. I am staying with MAP, Just becuz I will not have a single pipe to put the MAf onto, and my car is setup for MAP from the factory. Also I think that MAP is a little more precise becuz it measures vacuum and not air flow, and you do nto have the restriction.

[93vinx]

but how would all the extra air affect the map sensor, also what kinda low end loss are we looking at if we loose the runnner design? even a guess would be nice a couple of my contacs told me like 20 hp and 20 torque as there estimate which is alot even if you ain 20 at the top but only a dyno will tell

[Anonymous]

If everything works right...

I will get way more than 20, I'm aiming for a 60hp gain. Now, before you laugh, if a STOCK 3.4 can dyno out 240hp at the wheels with a box on top of the LIM, a setup like mine will be far superior. As far as lowend, it will be bad. I will probably have little on the downside of 4-5k. But with a 8000 redline that is ok. First I need a better oil pump tho.

The extra air would make the map sensor add extra fuel, which is perfect. Without boost, a factory MAP sensor will keep your air/fuels dead on even with some good mods.

[93LuminaZ34va]

I thought it was the opposite.... Speed/Density systems (with MAP) were more prone to need tuning for even slight mods, since all they see is vaccum, which is easily affected my timing, etc. MAF systems could see the difference in air flow (more or less) for whatever reason and trim the fuel tables to compensate, therefore making them more flexible to mods......

[Anonymous]

That is true. But the more mods you give your mtoor, the more air it can pull in. This in turn changes the absolute pressure in the manifold. So the MAP reads the change, and adjusts the fuel so it doesn't screw up the air/fuel ratio. And from what I have heard MAP sensors are really flexible, they can add a lot more fuel, or take away a lot depending on the conditions. This is how I can drive from 6000-7000ft straight down to sea level, and the car still runs perfect. With carbed cars, you can't do this. They would need to be jetted, and depending on the motor, a different sized power valve.

[93LuminaZ34va]

True on the carbs. But, MAF's have a MAP sensor too, it just isn't the prominent sensor in the system, and trims for altitude in the MAF system, just as it can in the Speed/Density..... I beleive there is also a BARO sensor in them too... or there was in my Camaro RS.

[RacerX11]

You are wrong, Aaron. The MAP doesn?t compensate as much as you think for increased airflow. The Speed-Density based EFI systems (MAP) are assuming a given engine volumetric efficiency for a given engine speed and manifold pressure. When you change something with the engine that affects the volumetric efficiency (ported heads, headers, intake, TB, etc.) you are changing how much air is flowing into the engine at a given engine speed and manifold pressure.

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.

If you are planning for 60HP over stock, you will definitely need some tuning. The MAF system is much more tolerant of mods, as it is measuring actual air mass flowing into the engine.

Marty

[brian89gp]

94-95 is MAF and MAF alone.

Marty is right, the MAF responds better (MAP doesn't really respond at all unless tuned) to mods.

If you want some MAF vs MAP go over to the thirdgen board, there are pages upon pages of topics on this very comparison.

[93vinx]

ok another thing i red was that you can put a delay on the map sensor and it launch you better, i guess when you do wot the map retards timings by putting it on a delay it holds off. btw this was out of a chevy performance book.

[Anonymous]

Then how does the car automatically adjust for altitude changes. Becuz I've had my car at sea level, and took it straight to 8400 and ti still ran good. Of course it lost power, but the air/fuel didn't change at all.

[RacerX11]

As you go up in altitude, your ambient atmospheric/barometric pressure drops. At sea level, the barometric pressure will be ~100 kPa (depending on weather conditions). At 8400ft, the barometric pressure will drop to around 73 kPa.

At WOT, your intake manifold is at the ambient barometric pressure, so at the higher altitude, the MAP sensor reads a lower pressure, and the ECM will put in less fuel. Your air/fuel ratio stays the same, but you lose power. In this case, the ECM is reading a point on the map and putting in less fuel.

This has nothing to do with compensating for increased airflow due to engine modifications. Your MAP sensor will never read a pressure higher than ambient (unless you have some sort of ram air or forced induction).

Marty

[SappySE107]

It also knows the ambient MAP pressure and adjusts in the computer for it. The computer scales it for you, with MAF, it reads the air coming in and works perfect without calculations. Only issues with MAF (if you can tune your computer) is that MAP is faster to see changes, and is closer to knowing the airflow at the valve compared to the MAF seeing the flow at the TB.

This thread should explain why I predict your engine is gonna blow up at sea level.

[Anonymous]

Than it won't go to sea level

No but I do not understand why this would make my motor blow. I could see if I did not do something to adjust my air/fuel, but if I take care of that I shouldn't have any problems.

Well I will borrow a buddys air/fuel gauge, and use that after I put them on. Even if it was off, the most it will do is not run right, smoke a lot, foul plugs, etc. Nothing that can't be fixed. He also has a fuel curve controller, like an emanage, so if that will hook up I can easily adjust fuel curves to see how that changes things and to see if I need a seperate controller. But I would think that as long as I take vacuum from all 6 runners, combine them and hook my MAP up to it that it should work fine. But I guess I am wrong here. What happens is you take vacuum form each port, usually via a 1/8" line. Then you have a vacuum "canister," like a box, that each line screws into. Then there is a connector for brake booster, MAP, and other misc vacuum lines.

SappySE107, do you think that we could add enough fuel with modifying the chip alone, or would it take more? But still, that will be a pita, sending it to and fro just to tune. Wish I wasn't halfway across the country.

[SappySE107]

With all the shit you have done or will have done, you need custom tuning which requires the car. The injectors are going to need to be upgraded most likely. At your elevation you will be better off because you wont see the full extent of mods anyway.

It wont blow right away but in its current state I would imagine a ton of knock and a lean condition at higher RPM. Not a good situtation.