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What do you think of the design of the air intake? It starts with a nice scoop in the grille, which does not quite meet up with the primary duct to the airbox. That duct is interesting, because rather than duct the cool air to the airbox, it just kinda runs it by the intake, with three openings to the engine compartment that at low speeds at least would get hot air to the airbox. It's cross section is reduced a bit by an foam insert, presumably for noise abatement. I'm tempted to pull the foam and tape up the holes and gaps to keep the air cooler to the airbox.
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Compounding that, the air box has a secondary intake that opens up to just above the transaxle at high rpm.
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I’m fairly sure that small filter in the tube is a hydrocarbon trap and more than likely it’s designed with those gaps because the vehicle components are moving and you’re not going to see “that much” escaped air upon constant airflow going into the tube from that front bumper inlet. Removing the foam from the section that goes into the box won’t really benefit it in any way that I see. Even if you tape the area where the foam was the hydraulic area is not any larger. Taping the vents on the tube might be some benefit but probably not noticeable. I do find the opening flap on the bottom very interesting though. I had the whole front end and intake apart this past weekend and it was cool to see everything.
 

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I think I saw this mentioned in some air intake comparisons and discussions. I do have to wonder if there is any zigzag section up front to help remove water before going straight into the filter box (a fairly typical arrangement); if not, the passthrough is probably for water to safely leave rather than entering the engine.

The gap between the scoop up front and the intake tube is almost certainly because the engine and attached airbox will move a bit and if that gap were bridged by something the material would probably fail quickly as it gets pulled and tugged.

The positioning of the light green foam doesn't look to me like it would be for hydrocarbons (at the intake? I sure hope fumes aren't sneaking out the front and I don't see what that little filter could do just on the side there) but maybe it is. I doubt it would hurt to try removing it.
 

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OEM intakes are very good. Most aftermarket intakes are poorly designed and will pull in hot air from the engine bay. When you see an intake test being run with the car stationary with the hood open and a fan being aimed at the engine bay, you're not getting accurate results. That's not how aero works in the real world.

You can see how good/bad an intake is by just monitoring the intake air temp sensor and comparing that with the ambient air temp.
 

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(I've also read that many gains from aftermarket intakes occur because of fooling the sensors into leaning the air/fuel mix and tend to give a rougher powerband.)

Probably a better intercooler (maybe with a homebrew GR-FOUR stencil haha) would help more. ;)
 

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(I've also read that many gains from aftermarket intakes occur because of fooling the sensors into leaning the air/fuel mix and tend to give a rougher powerband.)

Probably a better intercooler (maybe with a homebrew GR-FOUR stencil haha) would help more. ;)
I would always focus on making improvements after the MAF. on a Subaru, this was a turbo inlet, intercooler, intercooler piping.
 

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anything you modify on the intake or exhaust side will change the overall airflow. i wouldn't really touch that stuff unless you have access to the ecu to monitor all the critical sensors.

this is especially true when you remove the stock cat on turbo cars. you've now made the turbo more efficient and the ecu may not realize the restriction was removed and automatically adjust how to control the wastegate.
 

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Discussion Starter · #9 · (Edited)
The cage containing the foam looks like it would snap right out, increasing the duct area, but given the other intake it might not matter at all. No rain gutters in the grille scoop, so yes you'd need a bottom exit for liquids somewhere along the way to the airbox.

At the boost this engine is running compressor heat and intercooler efficiency are going to have the greatest effect on MAT, but every degree of IAT that goes in has to have an effect. Just thought it was an interesting setup on a car at a pretty high state of tune.
 

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anything you modify on the intake or exhaust side will change the overall airflow. i wouldn't really touch that stuff unless you have access to the ecu to monitor all the critical sensors.

this is especially true when you remove the stock cat on turbo cars. you've now made the turbo more efficient and the ecu may not realize the restriction was removed and automatically adjust how to control the wastegate.
absolutely. as time goes we will understand how much the stock ECU can learn with, or without a tune before things get dicey. people will toss a turbo inlet hose, intercooler, or replace the stock intercooler piping on the car, and pull logs to see if the stock tune can cope, then we'll know for sure.

there should be no question though, when you mess with pre MAF stuff you are absolutely changing how a critical sensor (the MAF) in the AFR calculation is going to read data. even if the diameter of the tube for the MAF housing is absolutely the same, if the way the air goes through that housing changes because the flow path ahead of it is altered, it will alter how the hotwire reads the flow.
 
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