Developing an ideal intake for a turbo setup

[BRZoomTX]

Originally Posted by STV3

If your intercooler is doing its job, then the intake should not matter at all on a turbo charged car.

Yes, but the colder the air goes in, the colder it comes out. Filter placement for street cars makes a huge difference. There is a reason the factory routed the snorkel for the intake outside of the engine bay. There is also a reason strip cars remove headlights or cut out bumpers for direct shots of air to the turbo rather than leaving them sitting in the bay with no filter. That cold shot of air makes a huge difference. It gets very, very hot under there N/A alone, much less with a hot turbo baking under there too.

The best two filter locations for these cars are behind the front bumper in the OEM snorkel location, or deleting the washer reservoir as shown in the pics above.

An alternate method I was going to try before changing plans, was deleting the washer reservoir, cutting out the OEM driver size DRL bezel, then making a "funnel" to shoot cold air up towards the filter (think the brake cooling kit, but one side only, and only a smaller tube to direct air up). This prevents changes to the intake itself and gets the desired cold air, along with no risk of water induction since you have nothing directly connected to the intake.

@IBill4You The cost to have a shop bend piping to attach with a new coupler will be completely worth it. Decide where you want it, then go to any local exhaust shop. As long as you use the same sized piping as your intake piping you will be fine.

[STV3]

Originally Posted by [Ron]

Yes, but the colder the air goes in, the colder it comes out. Filter placement for street cars makes a huge difference. There is a reason the factory routed the snorkel for the intake outside of the engine bay. There is also a reason strip cars remove headlights or cut out bumpers for direct shots of air to the turbo rather than leaving them sitting in the bay with no filter. That cold shot of air makes a huge difference. It gets very, very hot under there N/A alone, much less with a hot turbo baking under there too

Sucking 25-30 degree cooler air into a 1000+ degree turbocharger isn't going to make much of a difference. Maybe 1-2 whp if you are lucky.

If you are chasing down every last bit of HP or trying to cut another tenth off your 1/4 mile time, then sure it may be worth it. But for the average person I wouldn't over complicate things. I would just make sure to put the best flowing/biggest filter you can get on there.


Also I've owned a turbo charged car for about 11 years now and have had a CAI, Short ram, and straight filter on the turbo and it never made any difference on the butt dyno. Only difference you will notice is the sound.

[BRZoomTX]

Originally Posted by STV3

Sucking 25-30 degree cooler air into a 1000+ degree turbocharger isn't going to make much of a difference. Maybe 1-2 whp if you are lucky.

If you are chasing down every last bit of HP or trying to cut another tenth off your 1/4 mile time, then sure it may be worth it. But for the average person I wouldn't over complicate things. I would just make sure to put the best flowing/biggest filter you can get on there.


Also I've owned a turbo charged car for about 11 years now and have had a CAI, Short ram, and straight filter on the turbo and it never made any difference on the butt dyno. Only difference you will notice is the sound.

A 20-30 degree difference is actually quite a substantial change in terms of free horsepower. I invite you to review the following article to see how IAT affects power on intercooled turbo setups.

http://stratifiedauto.com/blog/the-e...rged-vehicles/

tl;dr: 20 degree drop in IAT showed large gains throughout the powerband and a 30whp peak gain on this particular car (MazdaSpeed6). Drive a N/A 86 before and after an e85 tune to see how much of a difference 30whp is in these lightweight cars.

Same dyno, same car, same tune, same day:

[IBill4You]

Just wanted to say thanks to all the big names (and all others) that appeared in here for input.

[King Tut]

Originally Posted by [Ron]

A 20-30 degree difference is actually quite a substantial change in terms of free horsepower. I invite you to review the following article to see how IAT affects power on intercooled turbo setups.

http://stratifiedauto.com/blog/the-e...rged-vehicles/

tl;dr: 20 degree drop in IAT showed large gains throughout the powerband and a 30whp peak gain on this particular car (MazdaSpeed6). Drive a N/A 86 before and after an e85 tune to see how much of a difference 30whp is in these lightweight cars.

Same dyno, same car, same tune, same day:

To be fair, that is a "Virtual Dyno" and not an actual Dynojet. With that being said, having the car out on the road with real world airflow through the radiator and bumpers should produce better IAT change results.

[BRZoomTX]

Originally Posted by King Tut

To be fair, that is a "Virtual Dyno" and not an actual Dynojet. With that being said, having the car out on the road with real world airflow through the radiator and bumpers should produce better IAT change results.

Just noticed it was an actual virtual dyno reading, although VirtualDyno is very accurate to actual dyno numbers when weight is calibrated correctly. Regardless, with the same weight and tire calibration on the same road, VirtualDyno does a good job of showing visible power differences, although the graphs above are over smoothed.

But very good point anyway. IAT would be affected even further once on the road. Any gains shown on an actual dyno by moving the inlet out of the high ambient temp engine bay would just be further increased on the street.

The best goal is to position the intake inlet or filter in an area where it will mostly (if not completely) take in air from outside of the car. Any position were a significant amount of air is being taken from the bay is poor placement. Taking in hot air from the bay is leaving free power on the table.

[STV3]

Originally Posted by [Ron]

A 20-30 degree difference is actually quite a substantial change in terms of free horsepower. I invite you to review the following article to see how IAT affects power on intercooled turbo setups.

http://stratifiedauto.com/blog/the-e...rged-vehicles/

tl;dr: 20 degree drop in IAT showed large gains throughout the powerband and a 30whp peak gain on this particular car (MazdaSpeed6). Drive a N/A 86 before and after an e85 tune to see how much of a difference 30whp is in these lightweight cars.

Same dyno, same car, same tune, same day:

Yes, but IAT is measured after the intercooler. I'm not saying that a lower IAT temps isn't going to net you more power, because I know it does. I am saying a CAI will not reduce you IAT's by much or at all if you have a proper intercooler set up. 25-30 degree cooler air being sucked in will not be 25-30 degrees cooler after passing through a turbo and all of the piping if your intercooler is operating in its efficiency range.

Why are you bringing up N/A 86's when we are talking about turbo charged cars. Two different worlds.\

Also, that dyno chart is only showing the difference in power between the higher and lower IAT's. Don't see anything about them achieving that via CAI.

Also the AFR seems to be leaned out a bit more on the higher HP run.

[IBill4You]

Aside from the AFR discrepancy and removing the intercooler from this equation just temporarily (because optimizing an intercooler specific to an application is a whole different topic) I assume your main point is that a lower pre turbo IAT will have either no or negligible affect on the IAT post compression (which causes heat as a byproduct).
I am not a physics major and would never remember the chem calculations. Can anyone conclusively say that the air post turbo compression will contain the same number of oxygen molecules regardless of pre compression temperatures? If my memory serves me correctly all equations will have a starting O2 density based on starting temps. Does anyone know what happens on a molecular level when the air is compressed that would make pre turbo IAT irrelevant or is this still a balance between reducing pre turbo restrictions vs pre turbo air temp variance?

[BRZoomTX]

Originally Posted by STV3

Yes, but IAT is measured after the intercooler. I'm not saying that a lower IAT temps isn't going to net you more power, because I know it does. I am saying a CAI will not reduce you IAT's by much or at all if you have a proper intercooler set up. 25-30 degree cooler air being sucked in will not be 25-30 degrees cooler after passing through a turbo and all of the piping if your intercooler is operating in its efficiency range.

Why are you bringing up N/A 86's when we are talking about turbo charged cars. Two different worlds.\

Also, that dyno chart is only showing the difference in power between the higher and lower IAT's. Don't see anything about them achieving that via CAI.

Also the AFR seems to be leaned out a bit more on the higher HP run.

1) Correct, but every little bit helps. Sucking hot air straight from the engine bay robs your motor of power. Why do you think nearly all OEM airboxes are closed with a cold air snorkel? The gains are proven. Replacing the factory intake with an aftermarket intake that does not replicate the same air source is a waste. Heat shields on aftermarket intakes help, but not as good as a properly designed intake getting a direct shot of air.

2) I mention N/A simply as an example. 30whp gains in this car are worth the additional effort due to the lighter weight than most cars. 30 free WHEEL horsepower is just a stupid amount to potentially leave on the table. I'm assuming you've never ridden in a N/A e85 BRZ/FRS because otherwise you wouldn't be arguing with the clear data here.

The difference from 150hp to 180hp is night and day. Even a tuned car making 160whp on 93 switching over to e85 is a very noticeable gain. Not to say you would always gain 30hp for a 20 degree drop in IAT, but there will always be noticeable gains. You claim you've owned turbo cars for over 10 years. Surely you would notice how much better the car feels during the winter months, no?

3) Moving the intake out from the engine bay to a direct shot of cold air directly lowers IAT. It doesn't matter how the example attained lower IAT. Any mod that lowers IAT supports the data.

4) Not sure what your point is with AFR either. The small .2 to .3 change in AFR doesn't equal 30whp.


The clear answer to intake placement is determined with a very easy task. Let your car run for 10 minutes, then lift your hood up slightly and hold your hand under the hood. Now, drive down the road with your windows down and hold your hand out the window. Where do you think the colder, denser air is?

If you answered "the engine bay", well I don't really have a response to that.

Originally Posted by IBill4You

If my memory serves me correctly all equations will have a starting O2 density based on starting temps

You are correct. There is only a certain point an intercooler will cool the compressed air down to, and that point varies by intercooler design, but cooling air starting at a much lower temperature clearly will increase efficiency. The compressed air coming out of the intercooler will be colder with a direct, cool shot of air, than taking the air source from a near blistering hot engine bay.

In hotter climates like the Southwest heat, it is even more critical to have a direct cold air source for the intake. That, or at least make sure you're running some sort of heat extraction out of the engine bay like functional side vents or a vented hood. In my case, I am doing both. Every little bit helps and is freeing up more power regardless of how little the gains are.

[Poodles]

If the car was supercharged, going to a CAI isn't going to help much because a SC doesn't heat the air as much. A turbo heats the air quite a lot, and while a good intercooler setup will do wonders, it can still heat soak.


If you really want to know the truth of the matter, put temp probes on either side of the intercooler and use a hot air intake and a CAI and see the difference on your own setup. I've seen this done enough times to know the CAI setup is superior.

[cdrazic93]

@King Tut, theres your mention, lol

[King Tut]

Originally Posted by cdrazic93

@King Tut, theres your mention, lol

I didn't even get the notification. Thanks though bro.

[IBill4You]

Originally Posted by King Tut

I didn't even get the notification. Thanks though bro.

I was kind of hoping that if I tagged one of you guys, then the others would make an appearance. I'm thankful for the presence of the knowledgeable boosted guys here for sure. I specifically tagged @Sportsguy83 because I knew he had a filter mounted directly to the compressor housing and tracks his car (although he is kind of cheating with that vented hood ).

[AVOturboworld]

Originally Posted by Poodles

If the car was supercharged, going to a CAI isn't going to help much because a SC doesn't heat the air as much. A turbo heats the air quite a lot, and while a good intercooler setup will do wonders, it can still heat soak.

"Keep in mind that higher temperature air isn’t a good thing, but it is a necessary evil shared by both superchargers and turbochargers because “when you compress a gas, its temperature will increase…” (Turbocharging, 2002, p. 1). Many people think that only turbochargers increase the intake temperature, because they are connected to the exhaust manifold. That is not true. Both systems increase the intake air temperature. "

Quoting somebody else to save some typing. Bottom line, it's the compression of the air that heats it up, not the heat of the turbocharger or supercharger. Keeping the air as cool as possible pre-compression and post-compression is thus important.