CAI vs. SRI articles

[AutoBox]

argh...basically a cai restricts the amount of air that flows to the turbo....same thing can be said about a full exhast compared to a dump pipe....the longer the tube the worst for the turbo, less responsive, more work to get the air needed...this fact alone out weights the "gain" u get from the cold air of a cai.....another fact to think about is that a turbo is very hot, especially spinning at higher then stock psi....even thou the air coming into the turbo is cooler with a cai it still exits the turbo at the same temp as air from a sri.....i wish someone would take the temps of the air after the turbo on a sri and cai setup and put this debate to rest....another fact is with the longer tubing of a cai u actually heat the air up before it gets to the turbo, especially when u are boostin 10-15psi , the tubin with all the bends causes the air molecules to bang into each other and distrbute flow to the turbo....if u look at any "good" turbo setup, u never see a cai anywhere, ram air...sure cus its not restricting the air flow, ur just throwin cold air at the sri....u want ur turbo ti havd unrestricted air flow just as u would want unrestricted exhast flow......leave cooler air duties to the intercooler, thats what its there for.....

 

[BrianV]

argh...basically a cai restricts the amount of air that flows to the turbo....same thing can be said about a full exhast compared to a dump pipe....the longer the tube the worst for the turbo, less responsive, more work to get the air needed...this fact alone out weights the "gain" u get from the cold air of a cai.....another fact to think about is that a turbo is very hot, especially spinning at higher then stock psi....even thou the air coming into the turbo is cooler with a cai it still exits the turbo at the same temp as air from a sri.....i wish someone would take the temps of the air after the turbo on a sri and cai setup and put this debate to rest....another fact is with the longer tubing of a cai u actually heat the air up before it gets to the turbo, especially when u are boostin 10-15psi , the tubin with all the bends causes the air molecules to bang into each other and distrbute flow to the turbo....if u look at any "good" turbo setup, u never see a cai anywhere, ram air...sure cus its not restricting the air flow, ur just throwin cold air at the sri....u want ur turbo ti havd unrestricted air flow just as u would want unrestricted exhast flow......leave cooler air duties to the intercooler, thats what its there for.....

Having owned several turbo cars before, having dyno tuned them, and having read lots of articles on this, SRI for turbo is better. I had a 300zxTT and this had been covered there in much more detial. My friend has a Supra Turbo and the same results found. It's just that the average owner of a MSP hangs out too much with owners of 'RICEY' cars where the whole idea of CAI sounds great. There are a handful of N/A cars where SRI is more powerful then CAI (Nissan Maxima is an example).

 

[Heathen23]

Try looking at the dynos for each product and make a decision. To each their own. I don't think a blanket statement applies CAI/SRI is better, I think design characteristics even the cone or shielding used plays a big role in the results.

 

[InsidiousMSP]

I'm convinced a SRI is the best for the MSP until I see someone with just a CAI and boost controller trap over 98.5mph in 85 degree weather like I accomplished with my short-ram (stock exhaust).

 

[jred321]

Huh?

*** RANT- ON ***

Amount?

I've asked this before on these debates but I just can't understand the pro SRI logic so here goes: If, at maxium boost, my engine is getting say 7psi of manifold pressure that is governed by the wastegate how on earth can you think that there is magically "more" air going into the engine based on what is before the turbo? What do you mean "more"
Especially if we know that same 7psi is going to be colder and denser with a CAI.

Please explain

*** RANT - OFF ***

boost pressure != amount of air, put simply

Having owned several turbo cars before, having dyno tuned them, and having read lots of articles on this, SRI for turbo is better. I had a 300zxTT and this had been covered there in much more detial. My friend has a Supra Turbo and the same results found. It's just that the average owner of a MSP hangs out too much with owners of 'RICEY' cars where the whole idea of CAI sounds great. There are a handful of N/A cars where SRI is more powerful then CAI (Nissan Maxima is an example).

try fitting a cai in a 300z or supra, a major reason why more people use an sri, convenience. especially when running bigger intercooler piping, bigger turbo, etc... space becomes limited

i personally want a shielded sri with a fresh feed of air, but the reasons people are giving are never hard facts, which is why this will never end

 

[BinaryRotary]

The intercooler is what ultimately determines the temp of your intake air charge. Heat from compression and ambient temps from close proximity to the exhaust will heat up air from the intake of a turbocharged car whether it's filter is right next to the head or peaking out the bottom of the car.

That being said, I'm not saying a CAI is useless. If you put a pot of hot water on the stove for 2 minutes it's going to be hotter than if you put a pot of cold water on the stove for 2 minutes, but what I'm trying to say is that intercooler efficiency plays a larger role than ambient air intake temps.

Its just that an SRI provides a shorter path and better effeciency. The air is going to be heated, no matter what you use.

Take it for what it's worth.

 

[boostaddict]

Perhaps the truth (who'da thought)

After thinking about this here's perhaps a good explanation of the SRI vs CAI. I'll stick with what I said earlier about the engine's getting the same amount of air since the pressure is fixed by the wastegate and the temp is going to be lower if it starts out lower via a CAI... *but* if the SRI give less restriction then the the turbo won't have to work as hard to make that set pressure. It's wastegate will be a little more open at peak boost so there will be a little less backpressure on the engine... which is good. Since it wouldn't need to work quite as hard you should also see peak boost sooner (not needing as much exhaust gas to drive it hard enough to make that pressure) which is all good too.

So that's my take it doesn't let "more" air in... but it takes less work to get the air in. Maybe another way to say it: SRI doesn't give you more, it takes less away.

Now we just have to wait and see from the AEM results which makes a bigger (knowing our tiny IC) difference lower temperature or less restriction.

 

[jred321]

http://www.rx7club.com/showthread.php?threadid=245867
there is not one correct answer...

 

[03MSPRO]

http://www.flyinmiata.com/index.php?action=product&itemid=85347

not enough room for a cai?

 

[jred321]

http://www.flyinmiata.com/index.php?action=product&itemid=85347

not enough room for a cai?

umm, i think we all know there is enough room in a protege for a cai. i dont think that was under question. i'm saying high horsepower cars don't use them in part due to the space constraint they are under. i'm sure you could find a 300z (not supra, they just take out their headlight) running a cai and running quite quickly, but is it worth it?

and im not pro cai (see my post above for what i am pro), i just don't see proof for either case, just lots of theories that aren't hard to test but nobody has

 

[AutoBox]

i think u guys are confusing a ram air setup to a cai....no supra i have ever seen has a cai, 300zx has a cai style setup cus the filters are already close to the endter of the headlights (jwt pop charger setup)....like stated above a cai will hurt more then help in a turbo setup, why worry about cold air at the begining if it gets chilled by then end (after hittin ic) ????? s*** even high hp n/a sets dont use cai.........and as i sated before ram air is totally didfferent then cai so dont confuse them.....

 

[BinaryRotary]

The real issue here is the intercooler and not the intake. The MSP has one of THE shittiest IC setups I've ever seen.

 

[jred321]

part of the equation is intake temp. if you have colder air after the compressor due to it being colder before the compressor, the intercooler will most likely still be able to extract the same amount of heat from the air, so it will be that much colder at the throttle body than warm air that was intercooled. that is the cai argument, the colder the air in the beginning, the colder it is in the end. the intercooler will be the major player, but if you can make the temps be that much lower by starting that much lower, is it worth the sacrifice in volume of air? by some people's arguments, it seems like they don't car about intake temp at all since the turbo will heat it up hotter than engine bay temps anyways and that the intercooler is everything, which we know is not true, as hot air getting sucked in will hurt. 300z's and supras use ram because of convenience, since the filter in both is right behind the headlight and the headlight can be removed to get a feed of cold air directly to the filter. so they are getting cold air, just a huge volume of it. the question is whether on our application or similar, where this isn't possible, whether the sacrifices are worth it, and that has yet to be answered and will not be because people have different goals for their cars, like there will never be a 1000whp protege owned by anyone on this board like the supra guys, so what they use for an intake might not be the best for our 200whp applications. has anyone measured the airflow by a cai to show that it is restricting in our applications and that the superior airflow of the sri is truly the way to go? or will the cai still flow more than our system needs? nobody has or will answer this most likely.
there is no answer to the question, and the intercooler is not the sole solution, as a bigger intercooler has its own drawbacks. it's all about sacrifices in different places to get a nice balance, and what one person sees as the way to do things another will see as the wrong way, but it is merely different.

 

[jred321]

No there is. Get a FMIC

then you worry about pressure drop, the turbo working harder than it would normally to make the same pressure at the manifold and therefore falling off on its efficiency, blocking flow to the radiator so the engine is running hotter, etc... it is not the only solution, there is more to the equation than simply the intercooler, although it is a major part. it's a game of tradeoffs, there isn't one perfect system for everyone, some people see some tradeoffs as acceptable, others don't. it's about preference and goals for the car.

 

[AutoBox]

i agree with u jred but thereis no point to fuss over this cus we dont know the intake temp after the turbo on a cai or sri application....but from common physics i will stick with the fact that a long tub with alot of bends is not more effeiecnt then a short one....like u said, someone has to see if the cold air the cai draws can overcome its ineffiency and creat more power.....but i will tell u once the colder air goes thru the longer tube it isnt gonna be much colder the a sri suxin hot air, basic thermaldynamics here as well....im actually tryin to draw logical conclusions until we have hard numbers for our cars......

 

[BinaryRotary]

I don't believe that a 20* drop in temp is going to make much of a difference when you throw it into a 450 degree oven. We're talking about air here, air heats up so quickly its ******* ridiculous.

 

[BinaryRotary]

Here is a link to an INDEPENDENT report on CAI vs SRI, made from just about every major company. Look at it, its quite suprising, AEM did the worst.

www.tprmag.com/issue/1/1_challenge.shtml

 

[4001]

then you worry about pressure drop, the turbo working harder than it would normally to make the same pressure at the manifold and therefore falling off on its efficiency, blocking flow to the radiator so the engine is running hotter, etc... it is not the only solution, there is more to the equation than simply the intercooler, although it is a major part. it's a game of tradeoffs, there isn't one perfect system for everyone, some people see some tradeoffs as acceptable, others don't. it's about preference and goals for the car.

Have people who have installed a FMIC had this problem so far with the MSP?

 

[jred321]

Have people who have installed a FMIC had this problem so far with the MSP?

what problem? there isn't a problem there, it is just things that will happen, regardless when installing an fmic. air flow to the radiator will be hindered. there is more pipe and area to fill, the turbo will have to work harder. they aren't problems, just issues to consider. and our radiator is tiny, i'm weary of it and would upgrade to a regular protege radiator if i was getting rid of the stock intercooler just to be safe, but that's just me.

 

[4001]

If theres more air intake coming from a FMIC would that negate the increased IC piping