long story short,got a new tune ,put stock 2000 up mass air meter and air filter box on.took the pro m open element cai system off to do this and now instead of about 14.5 lbs of boost i have a little over 13.now if the stock air box caused the boost to drop that much wouldnt that also cause a horsepower loss?no other changes but its not as strong as before the change.now i know this has been beat to death but if the cai kits dont increase horse power as some say then loosing boost i know will drop horse power.so,do i get another cai kit ,get the boost back,or leave it as is?and its mike tune so i know thats not the problem.

 

Your assumption is that the boost gain from an aftermarket filter is a real gain, and not just a measurement anomaly. I believe that it is an anomaly.

If you were really gaining a pound-and-a-half of boost, there would be a clearly measurable HP gain. But there isn't. On my stock engine with a JLP AF, I show as much as 11.5 lbs of boost. Yet I run 100 MPH trap speeds, the same as someone with a stock airbox.

 

A recent article in MMFF showed no benefit to a basically stock engine. Once boost is turned up along with other mods, the CAI did show some minimal gains. Kind of like longtubes.

 

The question should be "Does CAI make HP" the awnser is very little but like most mods the more HP your running the more you can add, can you really feel 5-7 hp, no, but the blower noise alone my be worth the price though. T

 

I just installed a MAC Intake and C&L elbow today that I bought from ebay for 130 used. The blower wine is louder and the trucks a little more throttle responsive. I would go with something like Chickenears or JLP. Thats what I was gonna get but got a great deal on my setup

 

Probably not. The stock air box flows less air, but it's cooler because it pulls it from the wheel well. The CAI flows more air, but it hotter because it pulls it from the engine bay. But it does compliment the blower whine.

 

Your VOLUME of air increased, but the air quality decreased. Hence, your boost goes up because of the added volume used by the supercharger,but with no significant H.P. because of the warmer air. I use my stock air Box with a S&B filter with a 3 inch cut-out and flange on the bottom of my box and a flex hose running to the front lower grill. this gave me the added volume I needed over the stock box. I dynoed 2-3 H.P. on average over 3 other trucks with exact mods on dyno day in Miami, and my boost was about the same as theirs. Just my 2 cents.

 

so i guess what everone is saying is leave the air box alone .but i still lost the boost but i guess what tim says is i lost the boost but it didnt really make any horsepower so if i want to get the power take the 6 lb pulley off and get a 8 lb pulley? it really sounds like i need a kb instead of putting so much hot air in with the bigger pulley.i do have the jdm-kooks headers and 4.10 gears so after no changes on the truck since i got it in 99 i think im going to get a kb or whipple unless i pull this wild hair out and leave it like it is.

 

I didn't say that at all. I said that I don't think that you really gain any boost when changing airboxes, so you don't really lose any when you change back to stock.

Other things being equal, you can't make more boost and not make more HP. So the boost gain must not be real.

 

I'm not really getting the explanation that the boost rises, but the warmer air causes there to be no HP gain.

First, there are plenty of folks with sealed aftermarket boxes. They show the same boost gain and the same lack of HP gain. Each pound of boost without increasing SC RPM should be worth about 15 rwHP. I gained an indicated 2 PSIG or more boost. I have run my JLP box with a sealed lid. Still shows the same boost as with the perforated lid. Where is the 30 rwHP?

Second, plenty of folks have shown that once the truck is moving fast, the underhood air near the filter gets pretty close to ambient. Where is the 30 rwHP?

Finally, plenty of folks have done dead-cold dyno pulls with the hood open and fans blowing. Where is the 30 rwHP?

I have not seen any credible explanation for the boost-gain-but-no-power-gain phenomenon. So the only explanation that I am left with is that it is a measurement anomaly.

It would be cool if someone instrumented the truck and explained it. Guaranteed "A" in shop class (and maybe even Physics).

 

What you talking about Willis?

 

Whats to explain??

 

BOOST[sic] is a measure of resistance.

If BOOST goes up, it doesn't necessarily mean you are making more power. the engine can only flow so much air through the heads and exhaust manifold and 4 cats.

I believe the boost gauge will measure more boost, but that doesn't mean anything.

Remember an engine is a giant air pump, the more it that FLOWS THOUGH IT, the more power it makes. plain and simple. If there is a lot of air trying to get into the engine, that doesn't mean that air is actually going through the engine, and producing more power.

 

Completely true statement. So let's apply it to the situation at hand.

If we put a wad of paper in the exhaust, the boost will rise, but the power will go down, which proves out the theory. Similarly, when the air is superheated by an overspun blower, power-per-PSIG decreases as the actual quantity of air (i.e., oxygen) decreases per PSIG.

But in the case at hand, everything is staying the same except the intake side. No resistance has been added anywhere. Two more pounds of real boost (which is measured in the manifold, I assume) will result in two more PSIG of cylinder fill, and more power. So the boost can't be real.

If we increase the SC RPMs, the indicated boost goes up, but so does the power. No so with the filter swap (at least on a stock motor).

Does anyone have a diagram of the boost measuring circuit? Maybe we can figure this out that way. What part of the circuit is changed when an air filter is installed?

 

thanks for helping me understand this alot beter than i used to .im sorry i didnt understand what you meant at first and didnt mean any harm.but i understand what everyone is saying so im leaving it like it is.it still runs fine and in this heat its not doing to bad.