JLT CAI or RAI? Whats best for NA...

[DSMach1]

Im not lookin' to FI the motor anytime soon, its my daily grinder. But for a bit more power and for the money, would a CAI or RAI be best. Its an internally stock motor with the exception of exhaust and canned tune. I plan on doing some sort of stage 2 cam in the near future and wonder which one would be good. Ive always been a fan of keeping the filter outta the engine bay, but i notice the same gains out of the RAI. Also, i ask this question cause i dont wanna buy the RAI then down the road find out that the CAI would be a better choice to go with, and vice versa if i bought a CAI originally. Oh, and im wondering if in fact a JLT intake will lean out a motor that isnt tuned for that piece. Thanks...

[Ben99GT]

I prefer the RAI, some prefer the CAI.

I hear these work pretty good too though...


I also hear they make more power than the C&L.

[DSMach1]

Thanks for your take on this, im thinking a RAI will be in my best interest. Nice picture

[3150Mach1]

The JLT CAI produces a couple more ponnies then the JLT RAI.

[Bad_Mach]

Originally Posted by 03Mach150BP

The JLT CAI produces a couple more ponnies then the JLT RAI.

IMO, the CAI looks alot better too. Only thing bad about the CAI, is you have to pull the Mass Airflow Sensor wires out of the stock loom so they can reach the relocated Mass air. But, not too big of a deal.

[Ben99GT]

Originally Posted by 03Mach150BP

The JLT CAI produces a couple more ponnies then the JLT RAI.

I do not subscribe to this theory

And I know that's what JLT will tell you, but I believe the increase in IATs (seen only in idle conditions) is more than offset by the reduction in inlet length and the elimination of the extra bend in the inlet tract. JMO

[ModularSpeed]

Originally Posted by Ben99GT

I do not subscribe to this theory

And I know that's what JLT will tell you, but I believe the increase in IATs (seen only in idle conditions) is more than offset by the reduction in inlet length and the elimination of the extra bend in the inlet tract. JMO

And that is why this guy is a good asset to forums ^

100% correct. Assuming both have similar temps when the car is moving, (+/- 1-5 deg.) who in their right mind would think the CAI would make more power?

I have datalogged both underhood and fenderwell kits on the same day, and when the car is moving the IAT's are pretty much identical on both kits. I think the last time I did it, the CAI averaged about 2-3 degrees cooler at speeds under 45MPH....above 45MPH the IAT's were almost identical.

Looks? Who wants that?

[Troll]

Originally Posted by Ben99GT

I do not subscribe to this theory

And I know that's what JLT will tell you, but I believe the increase in IATs (seen only in idle conditions) is more than offset by the reduction in inlet length and the elimination of the extra bend in the inlet tract. JMO

I would think the air temp difference would be greater when not at idle, since cold air from the fender has less time to heat up as it passes through the engine bay. Meanwhile, the RAI draws all its air from under the hood. Unless you still have the scoop hooked up, I suppose. Hmm...I guess it prolly makes less difference in a Mach than other cars, 'cuz of the scoop.

How does a shorter inlet make a difference? And how might the ginormous inner diameter of the jlt setups affect things?

[Troll]

Originally Posted by ModularSpeed

...the CAI averaged about 2-3 degrees cooler at speeds under 45MPH....above 45MPH the IAT's were almost identical.

What was the outside temp? If 2-3 degrees nets another ft-lb, why not?

Looks? Who wants that?

Hey, mine looks spiffy. It's got flames on it.

[ModularSpeed]

Originally Posted by Troll

What was the outside temp? If 2-3 degrees nets another ft-lb, why not?

Because 1-2 more ft. lbs under 45mph does nothing for me. 2.5 seconds or so of having another ft.lb out of 10-11 seconds wont net much.

Both kits are great, but IMO the RAI is a better choice.

[Ben99GT]

Originally Posted by Troll

I would think the air temp difference would be greater when not at idle, since cold air from the fender has less time to heat up as it passes through the engine bay. Meanwhile, the RAI draws all its air from under the hood. Unless you still have the scoop hooked up, I suppose. Hmm...I guess it prolly makes less difference in a Mach than other cars, 'cuz of the scoop.

How does a shorter inlet make a difference? And how might the ginormous inner diameter of the jlt setups affect things?

There is little IAT difference at speed, in fact, some here have observed slightly lower IATs with the RAI above 40 mph. At idle or low speeds, you don't have air flowing through the engine compartment hence lower (and more consistent) IATs with the CAI. But that consistency of IAT comes with added inlet length and an extra bend in the inlet tract.

You always want an inlet setup as short and straight as you can reasonably get it. Extra pipe length reduces flow and responsiveness, and bends in the inlet act just like adding pipe length. IIRC, every 90 degree bend acts as the the equivalent of adding 3-5 feet of overall length.

And if you're a drag racer, it's hard to beat the RAI setup with a yanked passenger side headlight. The air path won't get any more direct than that.

[na svt]

Originally Posted by Ben99GT

I do not subscribe to this theory

And I know that's what JLT will tell you, but I believe the increase in IATs (seen only in idle conditions) is more than offset by the reduction in inlet length and the elimination of the extra bend in the inlet tract. JMO

I've data logged the IATs (RAI/CAI/Stock) and all were consistent once the car was moving. The IATS at idle for the RAI were a little higher at idle but since you don't race at idle it doesn't matter. I gained 3rwhp after tuning with my JLT RAI but at $80 (used) is was worth it. I switched to a 3" UPR intake tube and the fit was much better and there were no hp losses but this was with the stock 80mm MAF. A 90mm MAF may lose a bit with a 3" tube though. In the grand scheme of things RAIs/CAIs don't offer much bang for the buck but they do make it much cleaner under the hood and allow easier access to some parts on the passenger side.

[Ben99GT]

Originally Posted by na svt

A 90mm MAF may lose a bit with a 3" tube though.

[DSMach1]

Wow, this is alot more information than i ever woulda asked for. Thanks alot guys...

[ModularSpeed]

Originally Posted by na svt

I've data logged the IATs (RAI/CAI/Stock) and all were consistent once the car was moving. The IATS at idle for the RAI were a little higher at idle but since you don't race at idle it doesn't matter.

YYYuuuuuuup.

[tmhutch]

Nice thing about the CAI it can be positioned so the air filter hangs a few inches below the front bumper. If a person doesnt have to drive their car through water puddles or heavy rain this is not a problem and it makes the CAI much better than the RAI. My before and after testing showed an improvement OVER the RAI on the dyno. Cant remember how much. Would have to search for my old post on the other boards. Unfortunately not everybody has the luxury of dry weather only driving.

[ModularSpeed]

Originally Posted by tmhutch

Nice thing about the CAI it can be positioned so the air filter hangs a few inches below the front bumper. If a person doesnt have to drive their car through water puddles or heavy rain this is not a problem and it makes the CAI much better than the RAI. My before and after testing showed an improvement OVER the RAI on the dyno. Cant remember how much. Would have to search for my old post on the other boards. Unfortunately not everybody has the luxury of dry weather only driving.

Really? So RAI with or without a shield, will make less power with the hood open, then a CAI on a dyno???

Was this back to back testing? What kind of power difference?

I do not doubt your experiences, but that is very hard to believe.

I could actually maybe see that happening (noticeable power anyways) if the RAI has no shield, and the engine/cooling fans are on....as I have seen NUMEROUS times where are car made more power with a shield, because of the hot air hitting the filter from the fans kicking on, throwing off the MAF.

[tmhutch]

Originally Posted by ModularSpeed

Really? So RAI with or without a shield, will make less power with the hood open, then a CAI on a dyno???

Was this back to back testing? What kind of power difference?

I do not doubt your experiences, but that is very hard to believe.

I could actually maybe see that happening (noticeable power anyways) if the RAI has no shield, and the engine/cooling fans are on....as I have seen NUMEROUS times where are car made more power with a shield, because of the hot air hitting the filter from the fans kicking on, throwing off the MAF.

Yep, good point. The previous system was actually a Densecharger so it drew air from inside the fender. Did the swap right on the dyno. I think the CAI with the filter exposed below the bumper line would be like driving around with a RAI and the headlight removed. On the freeway at speed or pretty much any speed it is REALLY surprising. Couldnt believe it everytime I hit the gas on the way home from the dyno.