How does MORE air intake Decrease Performance?????

[lukavichy]

This concept that has been floating around about lost horsepower with the K&N FIPK system, is hard to believe. They say there is a decrease of about 2 hp loss up to 3600 rpm, and then a increase in hp 4000 rpm and above. I have not heard of this decrease from actual owners of the FIPK intake system, so I think these other people are getting this Information from a dyno chart that I have never see on the K&N site. Can somebody send me a link to this chart???

Once again can somebody tell me how MORE air to the engine can decrease performance off the low-end!? It doesn't make sense?!? But im sure somebody has an answer to this and I would like to hear it. Thanks.

[arkie6]

Originally posted by lukavichy
Once again can somebody tell me how MORE air to the engine can decrease performance off the low-end!?

Well, if the computer thinks it is getting less air than it really is, then this will hurt performance.

Here is my theory why the K&N FIPK and similar setups have not performed as well as desired. Toyota made it difficult for aftermarket airfilter manufacturers to make a replacement system for the air filter box by placing the Mass Air Flow (MAF) sensor in the top of the air filter box. And they complicated matters even more by making the air tube at the point where the sensor enters an odd shape. It's about 3" in diameter, but it is flattened in about 1/2" at the sensor mounting. If aftermarket manufactureres don't duplicate this nearly exactly, then performance will suffer unless they re-calibrate the ECU accordingly (nobody that I am aware of offers an airfilter/revised software package for the Tundra like some BMW tuners do). Anyway, the MAF just measures air temperature and air velocity. The computer takes this info and calculates the mass of air entering the intake using the cross sectional area of the air inlet tube at the point of the MAF sensor. If you alter this cross sectional area of the tube, then you screw up the calculation and will likely end up with a leaner condition than desired. Now the O2 sensors should feed this info back to the computer and be able to make minor corrections, but very minor. I haven't looked at a K&N FIPK where the MAF mounts, but I doubt that it duplicates the factory air tube cross sectional area at that point. Even a small increase in diameter or lack of that 1/2" depression will result in significantly more air flow for a given velocity. That is my $0.02 on the subject.

If you want more air flow into your engine, just install a freer flowing drop in air filter (K&N, TRD, or Amsoil) and open up the inlet to the air box a little more. There are several options for this. That seems to be the best option at this point for a performance increase, and it's relatively cheap. But don't expect much change in performance from just this mod. For more info, do a search for airbox mods.

[KLS]

The engine does NOT get more air at lower rpms with the K&N FIPK.

If you thought bigger is better, Toyota or K&N would use 4" intake, or 5", or 6". It doesn't flow better. Why do you think Toyota has it's "Split Port Plenum/Induction System?" Why not straight 4" to the heads?

The system needs to be engineered for the flow rate. The K&N system is evidently engineered for street racers that run over 4000 rpm. It is not engineered for people that operate from 2000 to 3000 rpm. Why? I guess they think that is where their market is at. Would you buy their product if it added 15 hp at 2500 rpm and lost 15 hp at 4800 rpm? I would, but if they advertised with the whole truth, would it sell?

And, yes, K&N did have that dyno chart on their web site, and yes, I can't find it either now. I guess that it didn't sell enough intakes.
Ken

[lukavichy]

Thanks alot for the input, it has helped alot! Finally I get some good feedback on this stuff! Thanks again.

[lukavichy]

Does anybody out there HAVE the FIPK system for there tundra that can give some input on this subject about the performance of the K&N FIPK? Can you really feel the difference?

[Toasted Coastie]

I recently installed the FIPKII. It came with no directions, but was easy enough to figure out. I didnt put it on the engine until I had my new exhaust also. I put the exhaust and fipkII on at the same time. The more air being sucked in, the more has to be pushed out. Air flo cant just be more in and nothing else.

I find that yes, above 3k there is a big difference. Loss, if any, is not noticeable at lower rpms. I tow a boat and drive with the overdrive off most of the time, so this boost at higher rpms is nice. I find that at stop lights, signs and other standing still times, if I touch the gas to hard, i squeel alot.

I notice when my rpms get to 3k, the truck rockets, but it was always fast. sure sounds sweet though.

[HockeyFreak]

I've had the Gen II FIPK on my truck since last November. I have absolutely nothing bad to say about it! I do think there is a slight loss of low end, but anything above 3600 rpms....HOLD ON!! I am getting true duals put on June 1st, so we will see what happens then.


hf

[lukavichy]

Does anybody own the regular FIPK and not the FIPK II, that can tell me there opinion. Thanks for the info for the Generation II guys but im really looking for opinions of just the regular system.

[tremo]

Originally posted by KLS
And, yes, K&N did have that dyno chart on their web site, and yes, I can't find it either now. I guess that it didn't sell enough intakes.
Ken

The K&N FIPK Tundra dyno results are here:

http://knfilters.com/FIPK/charts/57-9014.jpg

You can also get to them under their FIPK page:

http://knfilters.com/FIPK/fipk.htm

by clicking on "FIPK Information by Part Number page". Look for Part #57-9014-1 near the bottom of the page.

Note that the graph looks different from the original as the torque curve is missing from their results...

Seee-ya,

Jim.

[ronkyker]

I have a paper copy of the dyno chart for the FIPK. I am really dissapointed in the performance. I installed Iridium plugs, JBA catback, and the FIPK on my '01 v8 and the low end really sucks now. You really have to nail it from a dead stop to keep the rpm's up and feel any torque. I think it was a lot better stock. Even the the power curve that K&N ships with the unit shows a drop in performance below about 3500 rpm. I don't know about you but if I get my truck over 4000RPM it feels like its is overworked. The truck stays below 2000 rpm in most of the driving I do and as a result of the mods it is very sluggish. Is it possible that I need to have it tuned? I am very dissapointed. Performance combos claimed I shold get 40 HP and 40lbs of torque. I feel like I have lost about that much. Any ideas?

[bloodypulp]

i'm guessing that an open intake can actually reduce the amount of air entering the engine. the airflow restriction may be decreased thru the k&n filter element, but it does not mean that more air will always reach the engine.

PRESSURE
the OEM airbox, by being restrictive, pressurizes the intake tract. moving air thru a smaller orifice will increase the pressure. without the airbox, the intake system relays on engine vacuum and movement of the vehicle. there is less vacuum generated at low engine speeds. at higher engine speeds there's more vacuum, so more air sucked into engine. the K&N intake is getting air from a relative 'dead zone'. the RamAirPerformanceSystem intake gets air from the front of the vehicle, instead of the front-side OEM airbox. the front nose area of a vehicle is the location of greatest positive air pressure. which is where you want to be if you are an inlet. but ram air is mainly beneficial at lower vehicle speeds, when relative airspeed is not high enough. so by using a K&N FIPK you are moving the powerband up, by not using ram air.

if you want to see the latest ram air designs in use, look at current motorcycle designs. the latest engine designs use centrally located ram-air ducts feeding into an airbox. reliable streetbikes are producing 200hp per liter naturally aspirated. the engineers have to be doing something right by using airboxes.

air will always take the path of least resistance. it will want to move in open spaces, not into your intake. the airbox will contain the air from escaping and maintain positive air pressure for the RAM effect. not to mention, reducing intake noise.

TEMPERATURE
the open intake is sucking in warm air. air which travels thru the radiator and around the various engine components. the OEM airbox gets its air from a cooler source, the fender area. similarly, the RAPS tube is getting cooler air from outside, not in the engine bay.