RAM AIR MYTH OR TRUTH

[SonnyakaPig]

Originally Posted by Wandering Scot

On our racebikes we found that with a VERY efficient ram air system and sealed air box we didn't see any positive pressure to offset the vaccum on the engine till at least 90 mph.
Keep in mind, this is on a much smaller engine; 600cc's.
I wouldn't even want to try to figure out at what point a 6.2 V8;s vacuum would be overcome.
Good info, thanks Ted!

The magazine, GMHTP, ran a test of a number of CAI's. Their test measured data when the car was driving between 40 and 75 mph.

They measured MAP in KPa and explained for their "testing, 100 KPa roughly represents normal atmospheric conditions and shows that the engine is consuming air without any restriction. Numbers higher than 100 represent extra air that is being forced into the intake by a "ram-air" effect, while lower numbers show a slight vacuum in the intake manifold."

Most of the intakes that they tested showed a slight vacuum between 40 and 75 mph, with numbers slightly less than 100 KPa, but there were a few intakes like the ADM street intake, for example, that maintained a 100 KPa result for one of the two runs that were performed for each intake.

The AFE intake showed 102 KPa at 40 mph, 101 Kpa at 52 mph, 100 KPa at 63 mph, and 101 Kpa at 75 mph.

Granted, there were a number of other relevant factors to consider for this group comparison, such as IAT drop, outside air temperature, and hp/tq gains.

It was a very interesting article.

I'm not claiming to know the answer on the ram-air debate, but I just wanted to point out these findings given your mention about when the vacuum is overcome on our engines.

[CFD]

The idea of ram air, back in its day was quite effective, but not in the way it implies. The early big block cars from the factory were feeding air through a 12" long snorkel with a 1 1/2" openning, adding any free flowing filter arangement had great bennefits in itself. Also keep in mind ram air was designed in the day of normally aspirated engines, an increase in air velocity does affect the the way a carburetor performs differently than it does fuel injection. In the case of Harley's longer intake tracks produce more power in general and "ram air" via velocity stacks etc. inreases air velocity, this along with the scavenging effect created by exhaust gases when the valves are in the overlap position produces significant hp gains, again on carburetored engines. With all that said the the early muscle car years with large hood scoops,cowl induction and ram air will always be what we think of when it comes to performance, it's in our blood, I'll even go as far as saying our kids will be putting scoops on their electric cars.

[MadMav]

The true mystery here is how Mr. Ted Jannetty builds all these cool cars when he spends 23 hours a day on this forum.

Mav

[ackeight]

Ram Air only works on SCRAM jets

[Mr_Draco]

Originally Posted by Wandering Scot

On our racebikes we found that with a VERY efficient ram air system and sealed air box we didn't see any positive pressure to offset the vaccum on the engine till at least 90 mph.
Keep in mind, this is on a much smaller engine; 600cc's.
I wouldn't even want to try to figure out at what point a 6.2 V8;s vacuum would be overcome.
Good info, thanks Ted!

The OP has the data. You need to travel at speeds in excess of 300 mph. There are a couple other threads on this and one has a post that goes more in depth into the math and that proves it.

[csjcsj]

So you are saying that the CAI such as Vararam is not letting any more air in as like the CAI, K&N, RotoFab etc..... Performance of the Ram Air CAI would only work if you were going like 300 MPH?????

[Mr_Draco]

Originally Posted by csjcsj

So you are saying that the CAI such as Vararam is not letting any more air in as like the CAI, K&N, RotoFab etc..... Performance of the Ram Air CAI would only work if you were going like 300 MPH?????

Yep. That's why most people now are calling them a OTR (over the radiator) CAI and getting away from calling them a Ram Air CAI.

[csjcsj]

Ahhh, I see. A friend of mine had a normal CAI (cant remember what brand), but someone (his mechanic) told him he needed a Vararam OTR so he could get more air flow in, for more HP, since he had a cam in it.

[third1]

Good read Ted

[axis]

Originally Posted by csjcsj

Ahhh, I see. A friend of mine had a normal CAI (cant remember what brand), but someone (his mechanic) told him he needed a Vararam OTR so he could get more air flow in, for more HP, since he had a cam in it.

Chilling your blinker fluid will also produce higher HP numbers since the air goes right past it on the way to the air filter.

[VADER SS L99]

So how does the LS1 WS6 get its extra 15hp? It has the same airbox as the normal Trans Am right? So was GM just lying to all who bought the car saying it had 325hp when it only had 310? Just wondering.

[Apex Motorsports]

Originally Posted by VADER SS L99

So how does the LS1 WS6 get its extra 15hp? It has the same airbox as the normal Trans Am right? So was GM just lying to all who bought the car saying it had 325hp when it only had 310? Just wondering.

They made that extra 15hp and then some. The difference was tuning. The SS Camaro was rated 325 also.

[zero]

ram air been big thing in sportbikes for years, many tests around to show the gains on a dyno and on the bike a speed. Here`s just one test

http://www.sportrider.com/tech/146_9912_ram/index.html

[JANNETTYRACING]

Originally Posted by VADER SS L99

So how does the LS1 WS6 get its extra 15hp? It has the same airbox as the normal Trans Am right? So was GM just lying to all who bought the car saying it had 325hp when it only had 310? Just wondering.

I owned both a 2000 LS3 SS Camaro and 2000 WS6 RamAir Trans Am.

The difference in the Ratings had to do with the Air box Opening, The Camaro Was 1/2 the size of the TransAm opening.

Really had nothing to do with the Hood Openings.

Ted.