Theory on aftermarket intakes

Increasing engine horsepower is like growing corn. To get more yield the farmer irrigates. Eventually, the corn has all the water it needs. What’s the next bottleneck? Probably nitrogen so add nitrogen. When the crop has all the nitrogen it needs then maybe potash.

How much power you can get out of an engine is determined by how much air you can move through it. So, find the biggest bottleneck and upgrade. Eventually or maybe right away the air box becomes a bottleneck, one of many.

The thing we don’t like to talk about is the engine itself being a bottleneck. Sooner or later if we keep increasing power, it is going to pop. So, if you wish to tread this path, first start out with a built engine with all forged internals.

I pulled a K&N out of my wife’s car a previous owner had installed. The pores in the filter were too large for my comfort. It was like looking through a fine window screen. But, it looked like it would flow more.

I know some people complain of the air sensor getting dirty when using this filter. Well, the rest of the dirt is going into the engine.

I drive a Mitsubishi product and if you install anything on it other than the factory air box the mass air sensor has trouble. This can be fixed by taking the vehicle to a tuner. That, I’m told can cost up to $500 per session.

People on the Mitsubishi forum have tested intake filter assemblies and we know what product filters and flows the best. So, I know what to buy if I wish to go this route but then I still face a tuner charge. I’m happy to stay with the factory box and if I want more flow I can always change the air filter sooner than recommended.

We have people on the Mitsu forum making 600 wheel horsepower out of 2 liters. There is not much you recognize when they raise the hood. If wise they will pull the engine and send it back to the builder once a year for inspection. This is amazing stuff to a poor boy like me.

Ooooo good topic! Ill opt in my opinions here:

Most of the cars I see with cone filters and a short intake install its just been slapped on basicly for the “trick” factor. Driving the car shows no difference other than a cool sound. I’ve seen the same cars tested a dyno with both multiple times and as expected saw no difference in torque/HP. In a buddies Jeep he noted a serious decrease in fuel economy almost right away. Granted, that may have been him just enjoying the differant grunty sound and putting his foot further on the gas pedal too. In some vehicles there was a small HP gain but how often to really go deep into your HP pockets? Almost never. It boggles me to death how people just don’t understand that if you want to accelerate better, or race to the next red light faster its improved torque you want.

I like sticking with the stock intake system. It was designed around the car and I don’t drive a crazy modified, high power engine around either. Most of the cars I work on are also just daily drivers that don’t need an improved intake. They need fuel economy, emissions passing, and reliability. Where I live is also insanely wet 2/3 of the year. I know it takes a lot of moisture, or a lake to hydra lock a cylinder up but the stock intakes on most cars do a better job of allowing moisture from road spray to separate and not get sucked into the intake. That being said the hydra locking argument could go on for days and days. I know what kind of water can go through and engine after a hose was accidentally pointed at the intake of an idling car. It didn’t die or lock, sputtered a bit, shot some grimmey moisture out the pipe and that was it. Has never skipped a beat since either. People forget that the old fashioned way to clean carbon from an engine was to spray water into the carburetor and steam clean the cylinders.

The cars I see and agree/understand having a short air and cone intake are usually ones that have had an engine swap to something more fun and there just wasn’t the room to mount the intake system that came with the car the engine came out of. In that same breath most of them are turbo engines that have some form of an intercooler on them so it doesn’t really matter if the going in is warmer.

As far as K&N filters go, I have used them in all my vehicles. I don’t believe for a second that you’ll get any HP gain from it. Yes, am OEM paper filter for my car is $8 and it would take 6 or 7 paper filter changes to equal what the K&N filter and cleaner/oil kit cost me, but its amazing how many people will offer you $10-$15 to borrow it over night and re do their filters with it. I know air flows differantly through my panel K&N filter because the noise it makes is different. Wether its better flowing who knows.

I tend to go with you’re better off changing the exhaust system first for something larger and has better flow first. No sense having the ability to get air in faster/smoother if you can get the exhaust out better first. Turbo or NA.

The coolest intake kit I’ve ever seen, also the most expensive is a replacement intake manifold for VR6/R32 VW engines with a turbo on them. It had super short intake runners and a built in liquid to air intercooler that ran on a small electric pump and reservoir mounted on the rad shroud filled with the same type of coolant the engine used. Everything about that system is designed for reducing air restriction. The charged air feed was direct and short from the turbo to the manifold, and the fresh air feed to the turbo was short too. Some serious brains went into that kit. It was a while ago but that car on the dyno was 400 and change horsepower. And sitting shotgun I was actually a bit scared at how fast it accelerated and drove. Thank god for grippy tires, biiiiiiig brakes, and all wheel drive.

I just find it fascinating that people will spend $100 for a 1 hp gain, when that same $100 could go into a full tune up that would probably bring back 5-6HP the engine has lost being run on old worn out stuff. IE Ignition components. It also fascinates me that people will spend $1000 on performance upgrades when the key fundimental parts like the block, crank, bearings, pistons and rings, all have 250,000+ km on them and aren’t going to improve.

Unless you race your car on the track it makes more sense to improve torque. Saying that I’ve learnt over the years that the best way to have more torque is to have more displacement.

One power mod I did make to my car that did give it a couple extra ponys and a bit more torque was swapping injectors out. The stock injectors -albeit not cheap- were just very basic single pintle ones designed for the economy box the car was sold as. I swapped them out for a set off a super charged version of the same platform. They have a much higher maximum flow rate as well as a much better and finer spray pattern. You can feel it particularly when you push the car into wide open throttle and the computer ignores the ECT and O2 sens. I did have to adjust the idle and Co mixture afterwards but it defiantly feels a bit zippier.

That was a good read about the propane. You don’t see a lot of that anymore. When will the topic of water/methanol injection come up? 🙂

This is what I have on in my car ,it’s made by an Australian company , it’s a lot bigger than the standard intake , the car is a 2005 Holden Commodore SV6 , with the 3.6 litre HFV6 –

also these , which are insulators , to give a cooler intake charge,
Do they work , well yes , to a degree they do , the car sounds throatier due to the intake and has a more torque down low , this is aided by the insulators , but however a bit has been lost at the top end ,
I look at like this , I’m a runner , if I went out with a peg on my nose and went for a run , it would not be long before I was left gasping for breath , a car is the same , its a big air pump , suck , squeeze , bang &blow, if you can help it breath better that has to be a good thing , if I was to fit a freer flowing exhaust it would gain a bit more , but I don’t like the sound that some of them make .