CAI question

[fbird3800]

Should i pay and get a slp or fasttoys ram air or do the free mod. Is the free mod just as good

[scottblack]

Fast Toys seals alot better than the homemade systems, and in almost every case is built better. It also has a warranty and manufacturer's guarantee. It is proven. I don't see why you wouldn't get one???

Scott

[HAZ-Matt]

What free mod are we talking about? Better than simply doing the Free Ram Air mod? Probably a little better. Beter than making the scoop yourself? Not really. It's a question of utility. Do you think the 1700% increase in price over one you can build yourself is justified by the increase in workmanship (which I will conceed that the FTRA may be built a little better than one can do in the garage) or the increase in gains (which I suggest would be minimal compared to one built by yourself)? I do not think that there is enough increase in utility to justify the difference in price. Need me to clarify? Here goes:
Commom areas of superiority claimed by FTRA (or SLP CAI, they are very similar, so I will simply discuss the FTRA which may be better than the SLP anyway)...
1. Better seal, as advocated by Mr. Scott Black:
I think the FTRA will seal better than a scoop that is not built properly, or built with minimal effort. With a little silicone, that can be fixed up in a jiffy. Even if it isn't there will likely be little difference in gains.
2. No seal means loss of "ram air compression" effect: Ok we know that to have a real ram air system that we need a sealed path to the throttle body. But wait a minute... fluid dynamics tells us that you can't get the air to compress at less than 0.6 Mach and that in order to do so you need a divergent nozzle (intake). FTRA as are all other scoops are convergent. Convergent nozzles actually decrease pressure according to the physics. Basically this means that you can't get a real ram air system on a standard street car.
3. The FTRA increases intake pressure by capturing air from a high pressure area. If you don't seal the homemade one, it will lose compression: I agree, if in fact that area of the vehicle is higher than ambient atmospheric pressure, then an unsealed scoop will leak compressed air. However, the problem is that the air pressure may have a higher dynamic pressure but not a higher static pressure. Dynamic pressure results from it's momentum, while static pressure is a property resulting from it's motion in it's container. There will be no noticable increase in static pressure (which is the increase that you need in order for ram air to work).
4. FTRA's better seal will prevent hot engine bay air from entering the scoop: Again, I agree. But the temperature effect on an scoop that is not sealed will probably not be very great compare to the amount of air that is flowing in from the main inlet of the scoop. This excludes air that may enter through the OEM intake slot.
5. FTRA has a block off plate: I made one out of aluminum to block my free ram air mod. It is very easy to make, and you can make one too.
6. The removable front rubber seal: I'm sure there is a way to make this too. However, I think that inclusion of this is odd. Especially on the LS1 models. There would have to be a very significant change in intake pressure to warrant use of this seal. I'd actually like to see some data comparing performance with this seal in, and with it out. Temperature differences between the ambient air at the intake of the scoop and the original airbox slot location are probably not enough to warrant blocking off the front of the airbox. I would assume that when the engine needs to breathe, it would be better to leave the extra source of airflow open. Again, I'd like to see some data.

So, basically it comes down to do you want to pay a lot of money, or put in some manpower to build it yourself? I'm sure the FTRA is well built, and I'm sure it does give nice gains (this is my littel disclaimer ;) ). However, if you have to spend the $170 on textbooks then you may consider going the cheap route and seeing nearly, if not the same, gains.

And that is my two cents. Also, I didn't invent the physics, I just reported it.

[ September 17, 2002: Message edited by: HAZ-Matt ]</p>