I've heard a legitement argument about the intake decreasing low end power, and it's true, after installing my intake, my Max doesn't "get up and go" like it did before I installed an intake. I actually have to wait (not too long) till at higher rpm's till I really get goin. It does, however, have more high end, but is it really worth it??? One would think so simply because of the y-pipe. Those who had the y-pipe before an intake know that w/out that intake upgrade, the y-pipe doesn't perform to it's true potential. But has anyone ever tested this? Is the sacrafice of low end power made up by the high end? Or maybe it's just me

 

if you want to help make up for some of the lost low end, by a UDP or if you have enough money, by a new flywheel. Both of these mods will significantly increase your low end.

 

Things that improved my lowend:

Y-pipe
B-pipe
Poorman's CAI

The reason the open cone setup take away a little lowend is because they lack the pressurizing effect of the stock airbox. If you wanted to have lowend teamed with the same topend as a cone setup, you should have done the Poorman's CAI. My car makes approximately 3-4 more fwtq from 2000-4000 than my old HKS intake. After 4000 rpms the Poorman's CAI and HKS intake flow nearly the same.

Dave

 

what about setting up tubing so that you can sort of do a ram air effect with the cone filter. i wonder if anybody has done this before, and if you gain more horse power by it. something to think about.

 

I agree. A CAI will give all the low end back along with the top end. I couldnt run worth a #$%@ at the track with the underhood style intake.

 

i lost a little lowend with just the CAI...i think when i get my Y and the rest of it all it will come back...

 

i thought exhaust work(y-pipe, mid-pipe, test pipe) improves highend while taking away lowend torque. the purpose of doing exhaust work is to decrease back pressure; however, a certain amount of back pressure is needed to provide torque at lower rpms. i think this is how it works:

when the piston is halfway or more on the downward stroke the exhuast valve opens and the pressure is released so when the piston is coming back up it takes less work to push the exhaust out. at higher rpms, a more free flowing exhuast decrease back pressure significantly and allows the piston to travel easier on the upstroke. but at lower rpms, if there is backpressure present, when the exhaust valve opens the gases escape more slowly so some of the pressure is still being used to push the piston down - thus creating more torque. without this back pressure at lower rpms, wouldn't you lose torque because the exhaust would just escape freely and not provide any extra pressure to help push the piston down? what do you guys think?

 

im not a mechanic but that sounds yeah that sounds logical

 

my cai give me more high end then low end, it didnt seem to rob from my low end. most intake/exhuast mods you do will help high end more then low end. because the higher your rpm is the more air its being sucked in and pushed out so the better it breathes and exhales, the better it going to perform. and in higher rpms is when it needs more air sucked and pushed out.

 

Actually, back pressure has nothing to do with it. Back pressure is bad. What you want to do is increase exhaust velocity. You've got to have exactly the right sized piping to get the best exhaust velocity. Contrary to popular belief, bigger piping isn't always better. To big of piping slows exhaust velocity and kills lowend torque.

The Courtesy B-pipe isn't really 2.5" ID. I've measured it and it's more like 2.35" or about .2" bigger than stock. The Courtesy B-pipe runs mandrel bends and a smaller resonator which improves flow and keeps the velocity at a good pace. The Stillen Y-pipe is about 2.50" exiting ID, 2.25" primaries, lacks precats, and uses mandrel bends. The RT cat uses the standard 2.5" ID. The stock muffler is 2.25" which means it could rob a tiny bit of power, possibly. Overall, this setup is very uniform and uses mandrel bends and has no real bottle necks. This is what creates good power throughout the rpms.

When I installed my B-pipe and custom made extension between the RT cat and B-pipe, my car felt much stronger from idle to 4500 rpms (torque) with little notable difference up top. My ets dropped by over a consistent .1 and my mph went up 1.5+mph consistently. Clearly my car is pulling harder down low because my 1/8th mile et and trap speed is where I saw most of the improvement. If the mod gained me more topend, I would have seen little improvement in the 1/8th.


Dave

 

I think that was what i was getting at.

 

Here's a post from someone on an Infinity board, that actually knows something:

Q-J Air Intake Mods Why Not? q45tech
(52/M/Atlanta, GA) 2/28/00 10:27 am
The following site contains 24 current tutorials on how engines work and factors to improve performance: everything from mufflers to rod lengths.
http://www.performanceprofessor.com/

EVER WONDER WHY? When you add a cone /Popcharger type air filter to Q or J that the idle is bad in Summer. (same applies to no mods but 30F vs 90F outside). The system is optimized for 60F (SAE standard temp) outside.
The air density (=% of oxygen) decreases by 1% for every 11F. Thus with an under hood cone intake you can lose 7% more or +20 horsepower easily if its 90F outside but 160F under the hood. The AC and radiator can raise the underhood to 180F plus in Summer traffic jam. The aluminum intake further heats the air. (Why new BMW M5 has hood vents).
We made a series of measurements with electric thermometers. This superheated air causes the MAF/ECU to go into overheat mode reducing timing and performance (very over rich) to protect against knock. Cone Dyno measurements with hood open and fan blowing cool (90F) air vs hood closed are dramatic.
If you live where it gets above 70F stick with stock air box and just drop in a KN element---better yet buy a box of 6-12 factory filters from TJ and change every 10-15k.

0(Dessert)..>>>...100%(Rain/Fog) humidity drops power 7%;
baro pressure (Sealevel) 29.92" uncorrected (not what TV weather reports)is 1% for every 300 feet in altitude. Thus Atlanta @1000' power is down 3.3%. Denver @5280' is 17.6% low on power.

 

The post above makes me even more jealous of those lucky sacks who get to run on sea level tracks on a cold and dry night.

Dave (stuck running at 1100' and 60%+ humidity<-freaking midwest)

 

Wait a minute are you saying my engine is gonna overheat b/c of my intake? I have a Stillen intake. So what should I put the stock air box back on? I'm not gonna put mods on my car if they're gonna mess up stuff.

 

By the way my intake increases my low-end power. The engine always had great torque, but now it seems to pull stronger, especially when accelerating in 5th or 4th gear from 30-55MPH, or say if you're powering up thru 2nd gear from like 5MPH. I mean isn't that what it's supposed to do also?