Injen Intake: Great Sound, Awful Performance

[Justin D]

Hey all,
I am really struggling with my Injen Intake. The heatsoak during the summer is just destroying the performance. Ive seen intake temps hit 150 (!!), and rarley can I achieve over 18 PSI of boost when the sun is out. I realize this is just the nature of a Short-Ram style intake, but I didn't think it would heatsoak this badly. Has anyone modified their Injen in any way to aid in intake temps?

 

[15performanceblue]

What do you normally see for boost? I have injen intake and have driven it hard in 90 degree temps and never once had a problem or seen temps get that high. I hit 24 PSI no problem cold or hot. You may have a boost leak there.

 

[Justin D]

Are you running a aftermarket turbo/ protune? Becuase the stock one maxes out at 20.5 on the stage 1 map. I see those numbers at night when the temp is low, just not during the day. There is no way your car is making 24 psi with a stock or OTS tune.

 

[dyn085]

Heatsoak on a SRI for a FI engine isn't a huge deal for intercooled applications. You'll get some lag from a stop, but I it shouldn't be limiting performance elsewhere. Being on the OEM FMIC will be more detrimental than the intake itself in that combination, mostly because the intake will allow it to heat up faster and it has a tough time shedding the heat.

 

[Justin D]

Heatsoak on a SRI for a FI engine isn't a huge deal for intercooled applications. You'll get some lag from a stop, but I it shouldn't be limiting performance elsewhere. Being on the OEM FMIC will be more detrimental than the intake itself in that combination, mostly because the intake will allow it to heat up faster and it has a tough time shedding the heat.

That does make sense. I am running Cobb's FMIC but I still have this issue. I know its not a boost leadk becuase it performs perfectly fine when its cooler outside. My charge temps rarley get above 10 degres over ambient..

 

[dyn085]

I assumed you had the OEM FMIC when you said you the stage 1 tune. I would load the stage 2 and see if the issue persists. Also monitor your CAT to see what you're putting into the engine and maybe an ATR user can weigh in with whatever temp limits/compensations are imposed on the FiST. Do you have any datalogs?

 

[Sekred]

Hi guys,

Any increase in Intake temps will result in a similar increase in charge air temps affecting peak power for a intercooled and turbocharged engine.

Here is a link to a Calculator for turbo and intercooler outlet temps.

http://www.stealth316.com/2-turbotemp.htm

 

[dyn085]

Hi guys,

Any increase in Intake temps will result in a similar increase in charge air temps affecting peak power for a intercooled and turbocharged engine.

Here is a link to a Calculator for turbo and intercooler outlet temps.

http://www.stealth316.com/2-turbotemp.htm

While this is true in theory, we are basically splitting hairs when discussing that in an optimum-power scenario and that can be verified by watching/datalogging the intake temperature and CAT while doing a WOT pull. Colder air is always better/preferred, but with an effective intercooler the temperature difference in CAT at WOT is going to be negligible. This is why you see most FI racecars set up with a filter bolted directly to the compressor inlet and a sizable, effective intercooler. If you watch your intake temp on a WOT pull you are going to see it plummet to at or very near ambient very quickly-within a few hundred rpm iirc.

Obviously that will do little for temps while stopped due to the lack of airflow through the IC, but outside of the amount of time it takes to shed that initial heat soak there should be minimal noticeable differences. This is where people have to decide between the trade-offs of drivability and racecar, and a lot of that is dependent on the vehicles use or persons needs. Someone using the Injen on a car that sees a lot of highway commuting is going to have a different experience than someone who predominantly stays in-town.

Which I suppose makes me wonder when the WOT pulls are being done. If they're being done shortly after having sat stopped then the higher CAT is going to affect overall numbers much more than if the car was being driven and then simply slowed down before initiating the pull. Either way, datalogging is going to glean much more pertinent and necessary information.

 

[BlueBomber]

Hey all,
I am really struggling with my Injen Intake. The heatsoak during the summer is just destroying the performance. Ive seen intake temps hit 150 (!!), and rarley can I achieve over 18 PSI of boost when the sun is out. I realize this is just the nature of a Short-Ram style intake, but I didn't think it would heatsoak this badly. Has anyone modified their Injen in any way to aid in intake temps?

I did

I modified my injen intake with a 90* elbow and a flat piece of plastic so that I created a cobb style sealed airbox using my injen intake and modified the oem lower airbox and the oem inlet to the airbox.

It resolved heat soak issues for the way -I- drive my car.

Your experience may vary, but you have everything but the elbow, coupler and new air filter needed to do what I did.

Opening up that hole where the OEM airbox draws from in the radiator shroud makes a big difference in intake air charge temps

additionally try using weatherstrip or something to better close off the injen heat shield where it meets the battery box, as that seemed to be where most of the hot air bled into the injen design heat shield from

however this only goes so far, which is why I went the airbox route.

 

[redsilvy]

I did

I modified my injen intake with a 90* elbow and a flat piece of plastic so that I created a cobb style sealed airbox using my injen intake and modified the oem lower airbox and the oem inlet to the airbox.

It resolved heat soak issues for the way -I- drive my car.

Your experience may vary, but you have everything but the elbow, coupler and new air filter needed to do what I did.

Opening up that hole where the OEM airbox draws from in the radiator shroud makes a big difference in intake air charge temps

additionally try using weatherstrip or something to better close off the injen heat shield where it meets the battery box, as that seemed to be where most of the hot air bled into the injen design heat shield from

however this only goes so far, which is why I went the airbox route.

Do you have any pictures of your setup?


My intake gets pretty hot as well but I still will hit 24-24.5 psi even on really hot days.

 

[Sekred]

While this is true in theory, we are basically splitting hairs when discussing that in an optimum-power scenario and that can be verified by watching/datalogging the intake temperature and CAT while doing a WOT pull. Colder air is always better/preferred, but with an effective intercooler the temperature difference in CAT at WOT is going to be negligible. This is why you see most FI racecars set up with a filter bolted directly to the compressor inlet and a sizable, effective intercooler. If you watch your intake temp on a WOT pull you are going to see it plummet to at or very near ambient very quickly-within a few hundred rpm iirc.

Obviously that will do little for temps while stopped due to the lack of airflow through the IC, but outside of the amount of time it takes to shed that initial heat soak there should be minimal noticeable differences. This is where people have to decide between the trade-offs of drivability and racecar, and a lot of that is dependent on the vehicles use or persons needs. Someone using the Injen on a car that sees a lot of highway commuting is going to have a different experience than someone who predominantly stays in-town.

Which I suppose makes me wonder when the WOT pulls are being done. If they're being done shortly after having sat stopped then the higher CAT is going to affect overall numbers much more than if the car was being driven and then simply slowed down before initiating the pull. Either way, datalogging is going to glean much more pertinent and necessary information.

I wouldn't call it Theory, a form of Physics would probably be a better description of what I was trying to explain.

As for turbocharged vehicles built for some form of track use, most make an attempt (what I have seen) to draw in colder air from outside the engine compartment whether that is by using tubing or by positioning of the turbochargers.

IC efficiency is fixed, colder air in equals colder air out.

 

[dyn085]

I wouldn't call it Theory, a form of Physics would probably be a better description of what I was trying to explain.

As for turbocharged vehicles built for some form of track use, most make an attempt (what I have seen) to draw in colder air from outside the engine compartment whether that is by using tubing or by positioning of the turbochargers.

IC efficiency is fixed, colder air in equals colder air out.

In science, a theory is the way facts are interpreted. While I understand that in the general population the word is used regarding speculation, the scientific community uses it in what is basically the exact opposite. In layman's terms, I agreed with you.

While I do agree with you, I still encourage SRI owners to datalog their intake air temp, ambient air temp, and charge air temp for comparison. What they will find out will support exactly what I've said both about WOT and general driving-charge air temps will be completely reasonable. The only discernible difference is going to be while at idle and stopped or accelerating from a stop-most notably on hot days.

Colder air in does equal colder air out in most situations, but we're still splitting hairs in the majority of driving conditions.

 

[Azov]

I really don't see what the big deal about the high intake temps are about. By the time you see how hot the compressor outlet temp is, and the charge air temp is, you won't complain a bit.

Yes it gets hot when I'm sitting in traffic in 100 degree weather but when I eventually move, that temperature lowers to about 15-20 above ambient.

 

[dyn085]

I really don't see what the big deal about the high intake temps are about. By the time you see how hot the compressor outlet temp is, and the charge air temp is, you won't complain a bit.

Yes it gets hot when I'm sitting in traffic in 100 degree weather but when I eventually move, that temperature lowers to about 15-20 above ambient.

What we're discussing is that the added intake temp adds to the compressor outlet temp. Not directly, but I'm sure there's an equation somewhere. That added temp has to be removed by the intercooler and causes it to heat up faster.

Also, 15-20 degrees over ambient isn't very good.

 

[BoostBumps]

Ignition Timing - Charge Temperature Compensations

Timing Compensations (CAT):

This is the base table for timing compensations based on Charge Air Temperature. The values in this table are multiplied by the Timing Comp. Mult. (CAT) table to allow fine adjustment in 3D form with RPM and Load.



This is the multiplier for timing compensations based on Charge Air Temperature. The values in this table are multiplied with the values Timing Comp. (CAT) table to create the final compensation.



Results for Different CATs:

CAT 70F = (+15.00 * 0.06) = +0.9 Degrees Added
CAT 100F = ( 00.00 * 0.06) = 0.0 Degrees Added
CAT 110F = (-25.00 * 0.06) = -1.5 Degrees Pulled
CAT 120F = (-43.75 * 0.06) = -2.6 Degrees Pulled

[HR][/HR]

Primary Differences between COBB stg1 OTS and COBB stg 2 OTS maps:

• +1.0 psi boost added
• ~ 2.0 degrees timing added lower Right Quadrant of Borderline Timing Tables (>1.3% load / > 4000rpm)
• Load Limits are slightly raised between each stage OTS map

 

[RAAMaudio]

ABS plastic will absorb quite a bit less heat than aluminum tubing, partly why it is used for intakes.

As noted sitting in traffic will heat up the air a great deal more as not much blowing through it so more time to absorb the heat.

Once more air is flowing through the intake it has less time to heat up and the under hood temps might go down a bit.

I heat wrapped my intakes really well to eliminate at least some of the issue, on my car I have a tubular manifold 4 inches or so below the intake so pretty much had to anyway and I have a grill mounted velocity stack to pull in real cold air(which could be heated a bit by the radiator in traffic).

Gold foil works the best but I did not care for the look so chose silver but neither is that great if just foil. I used foil/fiberglass cloth backed, then a layer of 1/8" fiberglass insulation with a heavier aluminum layer on it then to smooth it all out better, seal up any gaps, etc, one more layer of the aluminum/fiberglass cloth backed material. This is far more effective than a later of just gold heat tape.

I did not log temps before and after which I wish I had to show the benefit of the insulation but I can say for certain right after making a run, popping the hood to check things out, the tubing was a great deal cooler after I insulated it.

 

[BoostBumps]

Really did not see any appreciable difference between ABS intake tubing verses aluminum tubing...Particularly during cruising conditions with outside air constantly flowing through the intake tubes...





Impact of adding simple Intake Duct Extension tube....This small change made a noticeable difference...



Intake Duct Extension Tube:





CP-E CAI

 

[RAAMaudio]

Well done Sir!

 

[BoostBumps]

Well done Sir!

thanks Rick!

Adding the duct extension made the most significant difference...And just adding a hole there made things worse by drawing in hot air radiated from the front surface of the radiator....

 

[RAAMaudio]

Here is what I have built and later will mod a bit more when finished moving and settled in, rebuild the side of the radiator support for more direct flow and position the inlet right behind the grill, had to angle it for now and add more insulation to the tubing and at least the bottom of the air filter housing.
I will build a heat shield over the manifold as well as ABS ducting to force all the air as to go through the coolers as possible.

Best tuning run to date, 24.09 PSI, 280 WHP, 276 Ft Lbs, 86.6 intake temp, 94.4 charge air temp at 7399 RPM.
This is without anything sealed up to ensure proper airflow through the coolers, lots of air going around them out the sides, bottom, engine bay, etc. During runs in 70 degree weather the charge air temp was around 2 degrees over intake temp.

I will learn how to post up cool stuff like you guys do after I have moved and again settled in, finished the mods, etc...

Inlet fits snug in the cutouts for the bumper, etc...when the bumper cover is back on the car.
The aluminum tubing you can see in past the blue hose is tapered and smoothed for cleaner flow, I do this all the way through the system, intake to exhaust tip.

I will also open up the lower grill and looking for a way to make some nice holes in the bumper cover to flow more air directly at the IC and still look good, not much luck yet.