Alright I have been having some problems with my TII. It just isn't as fast as it should be. When its cold it is alot faster though. When I first turn on the car it will boost alot higher and hold the boost. Why is this? Could it be something to do with whats wrong with my car? Thanks alot.

 

A) you're getting used to the speed so what seemed fast now seems like nothing

B) Colder air is denser so when your intake temps are low you can make more horsepower and boost. Unless there's a HUGE difference between when you boost cold or hot I wouldn't worry about it.

C) I noticed similar symptoms before I blew my engine. As compression dwindled so did power and boost, but I doubt thats happening to your car.

 

Well I am sure I am not imagining it. I can get full boost in 2nd easy when cold and have trouble getting half boost in 3rd when warm. I can't really figure it out myself.

 

Why are you seeing full boost when its cold, ANYWAY!!

Thats the quickest way to go pop. Your turbo might be having problems making full boost when its hot. If theres a leak at the turbo flange, it will be worse when its hot. Check for intake leaks, too. Is your TB stock? If there is coolant flowing through it, your intake charge will be hotter. Hope this helps.

 

I bought my car in January. A few weeks after I bought it we had record low temps in the high teens. When I got off work on the weekends around 11 or 12 my car absolutely flew . Now that summer is here my car feels awfully slow

 

My 87 N/A seems the same way to me .. Its obviously not turbo related In my case.. but when the engine is cold I get alot better throttle responce .. and everything just feels more powerful. I haven't worried about it cause its just my comute/work car. I always attributed it in my own head to ... the engine being choked when cold (richer fuel mixture) and thus producing a bit more power. Maybee your car is running a bit to lean when warmed up ... do you have a A/F gauge?

 

i wanna know why youre running your car hard when its cold. like bob13bt said, thats a way to blow the engine. dont do that, at all. but yeah if your turbine is cracked on the housing somewhere, the crack will get bigger as the metal gets hot and expands. and if you still have the coolant line running through your throttle body, you need to bypass that. it is definatley affecting your power.

 

Well I have an egt gauge but not yet installed. All I have is an intake installed so far. I only ran the car cold a few times but noticed what happened and have been testing it. I am not sure if something is wrong with my engine or what but my car has some problems, performance wise. I want to get a compression test to rule that out then I will take the turbo to be looked at. I don't know about the throttle body, but my car is stock besides the intake. Thanks alot guys. Oh and you don't have to warn me about running the car cold, I know but have been testing things out to figure out whats wrong with my car. Thanks again.

 

This is really interesting. I am planning to buy an FC RX-7. I definetly look into this.

Also, could you guys please look at my other thread about restoring an FC RX-7?

https://www.rx7club.com/forum/showth...threadid=81104

Thanks!

 

Hot air just doesn't make as much power as cool air.

**** and this guy is POSITIVELY FULL OF hot air! SPAM removed by management... ****

 

You should not flog on a cold engine. Dosn't matter if it is a Geo Metro or a RX-7. You have metals that are not the same in your engine. They expand at different rates. They should be allowed to do that slowly. If you just beat the hell out of it when cold you will start the early death of your car.

That intake is probally part of your problem. Respect your car and it will return the favor.

James

 

So do all of you guys really think I can be losing that much boost from just warmer intake temps? My car runs pretty damn cool too since I got my fluidyne radiator.

 

Colder air is more dense than warm air. There are more molecules of air packed tightly together. So when the ambient air temp is, say 50 deg, there are more air molecules drawn into the intake than if it was 80 deg. Thats right, theres MORE AIR. With more air in a given space, you will make more power.

Cold weather is kind of a natural turbo or supercharger, just not as extreme. The engine doesn't run richer or leaner, the ECU compensates for the extra air w/extra fuel via the MAF.

And we're not putting the smack down on your driving habits. You know not to redline it until the temp gauge comes up to normal, right? Of course, otherwise you would have a post that says "Damn, blew my motor up, WHY?"

And yes, I have more power when its < 65-70 deg

 

Ok well I don't think the warmer intake temps would make this much difference myself. I dunno. Oh and something weird happened today, my car is alot faster. I hit full boost in every gear, actually a little higher than stock which I attribute to my intake. Pretty weird but I am not complaining. Want to go to the track now and see what I get.

 

Do you have a cold box intake, or is the intake getting hotter air as the radiator & turbo warm up? (I'm just an NA guy with the stock air snorkel.)
Bill.

 

Ok well all I have is an adaptor on my AFM and a cone filter on it. Thats it basically. Now my car is running strong and full boost. Don't know why but I am not complaining, lol. Think ima order my DP/MP now

 

you should never push your car into boost before its not fully warm, but i know someone beat me to this fact. its probably a leak somewhere soncerning the turbo.

Mike

 

WTF?

First of all, it has nothing to do with warm or cold ambient air The only relevant thing that will significantly affect performance w/ cooler engine is the efficiency of the intercooler. It will start to heat soak, and the efficiency will simply dwindle. The intact track can heat up and reduce efficiency as well, but it is marginal

Second, don't beat on your car when it's cold.

Third, it has nothing to do with what I mentioned above. You have a leak somewhere. Find it.

 

Ok, your telling me outside air temps dont make any difference in horsepower?!! Cold air is better for power!!! Yes, intercooler efficiency is very important too, as well as reducing chances of detonation.

Heres my point. If it is 50 deg outside, and the air intake temps after the intercooler are 80 deg, that is still cooler than 80 deg outside air and 110 deg intake temps.

Your ******* crazy man, last night it got down to <30 deg and my car has NEVER had more power. Oh yeah, but this is just my opinion....

 

Oh yeah. One more thought. When a car is cold the engine is tighter. The metal is contracted. So there for it will maybe have higher compression. As metal gets hotter it expands. And the compression may lower. Just a thought.

James

 

Sorry to burst your bubble but cold air DOES add horsepower. Why do you think they make CAI?? And if it was only for intercooler performance then why do they add HP to N/A cars?

my .02

 

Calm down people.

My point was that in-efficiencies in the intake tract are the only valid "hypothesis" you guys have managed to formulate. Of course ambient temp makes more power. But with the stock IC averaging less than 60% efficiency most of the time, you will find that FAR more is lost through it, than will be seen with ambient temp. changes.

This is not even a valid point, as I stated above. He has a leak and he needs to fix it.