Notice less power on warm days?

[ericem]

Just curious if everyone else experiences this as well or if it is more related to having alot of intake leaks?

[kimokalihi]

LOL you should make it so you don't have any intake leaks. That'll really mess up the way your car runs.

[93forestpearl]

Weather affects turbo engines significantly. Air temperature and humidty affect how much air your compressor moves, along with the change in effectiveness of your intercooler. It's normal for the butt dyno to notice less power at 95 degrees and humid vs. 65 and dry.

[ericem]

Hmm, today was very humid and kind of warm. Good or bad? Car felt extremely sluggish like response is far down. Yet on a cooler day car feels awesome pulls very strong.

I am not saying I have air leaks, saying if I do how much it will affect it. I really need to relook of my intake. Maybe ill spray water. I really wish I could pressure test the intake for leaks with a pump need to make something somehow.... I know siliconeintakes sells something but it's so expensive.

I think if the car would get 450km + out of 52L I would be happy. What is most annyoing is driving at the pace of traffic doesn't seem so easy seems like I have to give it so much throttle yet I can't really keep up..... or lets say if I wanted to pass I really have to floor it, yet when it's cool I can just stay at 1/4 throttle and the car pulls strong and I am pretty happy lol.

[ericem]

Aha! Got a idea for tomorrow

http://cgi.ebay.ca/AUDI-S4-RS4-TURBO-BO ... arParts_SM

I also have a valve stem.

[kimokalihi]

I'd like to do a little pressure test on mine.

[ericem]

Let me stop by lowes tomorrow and ill show pics of what I came up with.

[Apex3]

Yup, heat slows you down, why do you think everyone wants CAIs?

[cj91legss]

hmm yesterday i too was experiencing some not so great times while driving...

[ericem]

Technically stock intake would be a CAI, I also need to make a heatshield for the turbo as the IC gets very hot especially when sitting.

[gijonas]

In my car i notice this daily.I can pretty much feel a difference when i drive through a section of road where the clouds are shading the sun.

[Apex3]

Technically stock intake would be a CAI, I also need to make a heatshield for the turbo as the IC gets very hot especially when sitting.

I know, I just meant that's why people care if their intake is cold air. From what I've seen the majority of cars have CAIs stock.

[ericem]

Hmm, was busy today and never got around to it, but have it all on paper on a easy to make boost tester.

I honestly believe the stock BPV even though I spent $100 to replace it, it still leaks. Depending how I hit the throttle it sometimes takes of perfect, other times laggy and hesistant. Let me tell you guys I have replaced alot of parts, fuel pumps, only thing I didn't replace was the fuel filter, and sock on the fuel pump which will go in tomorrow.

Also oxygen sensor is damaged and wiring is all damaged and cut up, also debating knocking out the cat in the mid pipe. I have a catless downpipe and I am not sure how the 2nd cat is holding up or if it's even doing anything. Will post progress as to what replacement of all sorts of parts does lol.

[tturnpaw]

It's called heat, friction, and normal wear and tear. Not only that but higher intake temps mean the ecu will be retarding timing to stay further away from detonation. Which alone will back down power. Heatsoak is your enemy too.

[wtdash]

Heatsoak is your enemy too.

My TD04/TMIC is heatsoak-central when temps get above 80F.....Not helped by the small stock scoop. I don't have any measurable proof, but the car is just slow when it gets above 80.

I either need to go FMIC, AWIC, bigger scoop, IC sprayer, or Meth cooling.....or all of the above.

TD

[kimokalihi]

All of the above? Haha. Good luck doing a FMIC with an AWIC and a big scoop (which serves no purpose with FMIC lol).

Does meth require any sort of engine management or ECU modifcations? Or can you just start spraying it in on a stock setup?

[wtdash]

All of the above? Haha. Good luck doing a FMIC with an AWIC and a big scoop (which serves no purpose with FMIC lol).

Dude...it was a joke! Give me a little credit....

Does meth require any sort of engine management or ECU modifcations? Or can you just start spraying it in on a stock setup?

Yeah, it'll require something...haven't done enough research.....But Lee/Skid542 ran it on his stock setup w/13 (?) PSI.

[tturnpaw]

Wtdash, can you log your intake temps and ambient temp? If you can considering I have the same setup but with fmic we might be able to see some good results from an fmic. Then I'll take video on spool etc before I upgrade. Are your 25d cams reground? It won't be too long till delta has mine.

[wtdash]

Wtdash, can you log your intake temps and ambient temp? If you can considering I have the same setup but with fmic we might be able to see some good results from an fmic. Then I'll take video on spool etc before I upgrade. Are your 25d cams reground? It won't be too long till delta has mine.

No. Don't have the temp sensors.

My DOHC cams are EJ20K Turbo cams....they're in my Forester project...which is still 'in transition'.

TD

[tturnpaw]

Does anyone have profiles for those cams to compare?

[brweber352]

(Has been edited to remove false information)

This is why I went FMIC. In the winter the TMIC was great, but when summer rolled around it was horrible, espeacially after sitting at a stop light. I used to love waking up really early in the winter to drive to work early just to get the sub 30 degree wheather. One thing I used to do was grab a cup of ice and dump it on the TMIC in the afternoon on the way home, or whenever I felt like adding a lil extra power. A large cup of ice is pretty cheap at gas stations, and free at your friends or home. You will actually notice the idle go down and start to lope when you do this, kinda like a cam installed.

Brian

[93forestpearl]

General rule of thumb, every 10 degree increase in intake temps = 1% loss in total horsepower. Every 10 degree decrease in intake temps = 1% gain in total power. This applies to NA and Forced induction. Basically, a 200hp engine at 50 degress will make about 210hp at 0 degrees and 190hp at 100 degrees.

1% for ten degrees is really really conservative. The amount of fuel one has to pull amounts to much more than that. I've witnessed much larger variances on cars given the same dyno. Granted, 99% of the tunes people pay for do not account for temperature within a reasonable amount of error.

You can also gain more power by lowering the temp of the FUEL. This is why almost every new car has Electronic Returnless Fuel Systems, on our cars the leftover gas that is not used is returned to the fuel tank. Think about how hot that fuel gets when it goes up into the engine compartment,then that hot gas goes back into the tank, do this continually and the gas in the tank starts to raise in temp. New cars utilize a regulator built into the pump so it doesn't have to travel as far and get hot before it's returned to the tank. I'm still learning about these sytems, but it makes huge sense when you think about it, these cars also utilize a fuel temperature & pressure sensor. I think some of them don't even use regulators(at least not in a traditional sense), but rather sensors and a module to control the voltage to the pump to vary the amount of fuel being pumped to the rails under different loads.

No, it really doesn't make sense. The longer fuel sits in the engine bay the more heat it soaks up. Keeping the fuel moving through the engine system and back to where it can actually cool is better than the fuel sitting in the rails and lines waiting to be used.

Find me a fuel system in a higher horsepower car that uses a returnless system. There are none. New Subarus really don't use a returnless system either. They do use a fuel pump controller, but it goes away when people really mod them beyond silly "stage" crap. Not that it really matters. There have never been heat issues in any Subaru that I know of when it comes to the fuel system. This includes pretty wildly modified cars with pipe sets that introduce massive amounts of heat into the engine bay. Still no issue.


Anyways, for people that it really matters to, they utilize a fuel surge tank with two more three pumps. Its pretty simple and I'm going into detail here.

BTW. Technically, our cars have a standard airbox with a air pickup located facing the inside of the fender, this is not a CAI. A CAI actually locates the filter inside the inner fender well, usaully at a low spot to pickup cool dense air, they also utilize a conical/spherical filter which has more surface area than a stock panel style filter. Don't get me wrong, our stock intake is pretty good as it is, but it's not a CAI. Just because I point my custom intake towards the hole going to the inner fender doesn't make it a CAI, it's just a short ram that gets cooler air than if it was pointing somewhere else.

Brian

Seriously? The level of the filter is by no means a qualification for ingesting cold air. LOL. The air the car intercepts is not going to be colder 12 inches down from the factory location. Dear god.

An intake is all about the amount of fresh air available to the plumbing, whether it's 10 ft in the air or 10mm off the ground. Placement doesn't matter. If you pull the foglight cover off the SS bumper cover and keep the factory plumbing, viola, you have a cold air intake.

Also, don't count on conical filters having more filter surface area than a K&N or whatever. Have you ever actually measured the pleat number, depth, and length on a conical filter? You will be surprised what you find, and what is not published (ahem, K&N). Besides, 98% of stock mount turbos would struggle to find the limit of the cheapest conical filter.

[brweber352]

93forestpearl, I have read alot of your posts and you have way more knowledge about all this than I do by far. I can only hope to someday amass as much knowledge as you have about making serious power. I have no option but to trust your knowledge and experience.

My knowledge has come from magazines, internet forums, and various people that claim they know what they are doing. My only experience at making more than stock power has been on this sole subaru. This has been my largest hurdle in learning, since I have to trust what people say and write. Of course different people have different theories and opinions on what works and doesn't, and different engines and setups will respond differently (from what I've heard and read). So I guess most of my knowledge is useless until implemented, and I can make my own opinion on what works and doesn't.

In the furture I will only post knowledge that I have collected from hands on experience, not what I have merely heard or read from various sources. I apologize for posting false information. I will edit my above post so more false information is not passed on to someone else.

Thanks for clearing that up 93forestpearl. To the original poster, sorry for cluttering your thread with false information.

Brian

[wtdash]

My car seems to run better in the heat w/the AC on. Is there a reason for this?

[Legacy777]

My car seems to run better in the heat w/the AC on. Is there a reason for this?

Can you define "run better"

That can mean a whole lot of different things. With the AC on there's more load on the engine, and they do tend to idle better. But beyond that....not sure what else would constitute "running better".