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Air Filter Location Arguement


KG78Z

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I am in the process of having a 280zx turbo engine put in my 78 280Z. The guy I have doing the install for me and I got into a bit of a discussion about the location of the air filter. He (the mechanic) said it needed to be up in front of the IC. I said he should just keep it in the engine bay. His arguement was that the colder air from the front of the car would make more horsepower. I said that the temp of the air coming in was not that big of a deal since it was going to get seriously heated up going through the turbo, then cooled down from the IC. It would be much easier to keep the filter in the engine bay. Which would be the best? Thanks for the help.

KG78Z

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If you can, put it in front of the I/C. In my case, I selected a cylindrical shaped filter by opening random boxes in the auto parts store. I mounted the filter right behind the left headlight. If you look up from underneath the car, in the wheel well, you will see there is a nice "box" area that is somewhat protected from road debris and splash up in the fender against the rear of the headlight bucked. I fit a 5" round by 6"long filter up in there and hold it in place with a metal bracket bolted to the tow hook bolt. The 2.5" intake hose runs from the filter, down under the frame rail in front of the sway bushing, and back up behind the radiator to the AFM and Turbo Inlet. In this location, it gets cool air and it does not block front end airflow. Getting the 2.5" tube up behind the radiator required oval tubing (round steel pipe and a vice) for a short section. If you want some photos of this setup you can start here. http://www.hvmp.com/dc or I can take some updated photos and post them. The bellypPan needs to be left off or modified for this to work.

 

I am not sure if the added length of intake is offset by the cooler temp of intake air in my case. Whatever the case may be, the car runs strong.

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I would keep it in the engine compartment if you have a turbo. There is no point in getting cold air from in front of the intercooler (and blocking air going thru the intercooler) by having it in front of it. I am in the process of making a seriously turbo'ed Z and I am going to either put the K&N filter directly off the throttle body or piping it somewhere in the fender so it might still be able to get a little bit of colder air. Others thoughts are welcome though.

 

Aaron

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It is absolutely worth your effort to get cold air on the inlet side of the turbo. You mechanic is correct 100%.

 

I would keep it in the engine compartment if you have a turbo. There is no point in getting cold air from in front of the intercooler (and blocking air going thru the intercooler) by having it in front of it. I am in the process of making a seriously turbo'ed Z and I am going to either put the K&N filter directly off the throttle body or piping it somewhere in the fender so it might still be able to get a little bit of colder air. Others thoughts are welcome though.

 

Aaron

 

I think you need to study some basic turbocharger theory before you start building any type of "seriously turbo'ed Z". I am not sure how you plan on putting the filter on the TB and still running a turbo. Are you planning some kind of suck through design with the TB before the turbo? Why? It is a flawed design that way, though it can be made to work. There is little reason to go this route however with the abundance of turbo 280zx engines out there which are really an easy swap into any 70-83 Z.

 

I really don't want to have to get into the theory of why and how you need cold air for your turbo inlet, but you do. There is tons of info allready written much better than I can write on the subject both on this site and other places on the internet. I suggest you guys do some reading and learn exactly why cold air is a good idea.

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I would have to agree with Drax, when I built my motor I wanted every possible horse I could get. Not to mention the possible damage cause to the motor when you detonate because your sucking 120 deg air while racing during the summer months. I think its crazy not to get it out in front, mine does not block my IC or my rad. Any one who knows how turbos work will tell you to put it out front!

. I said that the temp of the air coming in was not that big of a deal since it was going to get seriously heated up going through the turbo, then cooled down from the IC.
The hotter it goes in the hotter it comes out. :idea:
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I will agree with everyone who said get it out of the engine compartment. I would also like to add that the shorter the tubing between the filter and the turbo the less chance for air to pick up heat.

 

As far as being in front of the intercooler, I don't see that as much of a problem, because for the most part, on the street, the intercooler is like a heat sink for the air passing through it, when you are off boost it will cool down again, and we just aren't on boost that long for the small amount of blockage that a filter causes to be a big issue. JMHO, but if someone has empirical evidence contrary to this, I would like to be enlightened.

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Guest bastaad525

yeah get it up front, but you dont necessarily have to block off any part of the I/C to do it either. My filter just pokes straight out from the radiator support, sitting right next to the I/C, not in front of it. Not that I think it'd matter much if it was in front of it, I just didn't feel like springing for the expensive 90* bend mandrel pipe they sell for that.

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