CAI diameter

I recently came across cold air intake layin in the garage from a previous project . Another tip for the sweeper! I had to alter it to fit, but managed to keep sensor intact, with some drilling fit like a glove. I later used some more garage/basement goodies and a couple trips to hardware store, to fabricate a ram air/forced induction type inlet. I installed it in my lower air dam, and amazingly it works great. But I wonder, after ready IAT sensor threads, if Im even using the right size tube diameter as cold air intake. Wanted to see if it made any difference before investing in a new CAI. Any ideas on a good manufacture for CAI on our engines? Thanks. I will try to add pix asap.

I call it the ram air-grabber! Lol.

What diameter tube did you use?

Im not positive, but it is smaller than original equipment. Its also a bit smaller than throttle body opening, the rubber adapter is notched down so I would say 3 inch? You can see it better here.

Assuming you've done nothing else to the engine or exhaust, this set-up is probably adequate for intake air flow, but I question the effectiveness of the cold air duct, as the filter has full exposure to the hot engine bay. The result is likely that your engine is breathing about the same amount of air as before, and now it's warmer air, which is not good. You may want to scan for IAT & KR before doing any WOT runs, or further modification to the engine. just my .02.

The open cone in the engine bay works on NA set-ups, and in some intercooled turbo intalls, but for a roots blower application like ours, it could be the kiss of death. Virtually all modern intake systems are very careful to seal off the engine bay from the air intake, and for good reason. Colder air is HP, and in our case it's insurance against knock (aka the devil).

With the airbox gone and the underhood intake being metal it will **sound** meaner. ...looks interesting and decent workmanship.

You'd get more air (at peak) with the standard airbox with the "muffler" removed - there's other info on how/why to do that elsewhere on this site - reason is the air's drawn strictly from outside the (warm) engine compartment and the rubber air horn tends to insulate the air making the trip into the TB. The set up you have should work OK, but the comparison's kind of like a couple kids drinking thru straws. No matter how big you make the cup (the air filter) at a certain point the rate of drinking is limited by the diameter of the straw. The kid with the smaller straw, all other things being equal, can slurp less volume of drink per unit time.

There are others on the site w/similar cars who can measure knock retard with their scanners. Do you have a scanner? If so you could compare figures with them and judge by the data if this is helping or hurting; I could be wrong. Data would tell.

Others on this site have made a similar setup but with a homemade box to cover the cone filter from engine heat. I'm sure this would help. The box would also aid in making sure the air coming from the scoop is actually taken in by the intake instead of flowing into the rest of the engine bay.

Based on your 4th picture, that air filter is not adequate for even a stock L67. That doesn't even address the size of the pipe or the fact that it's a warm air intake. Like Albert said, a gutted stock box would most likely perform better.

You want the pipe to be at least as big as the TB. If you don't mind having a warm air intake, just stick a 4" ID x 9" cone filter into the stock rubber coupler.

While we're on the subject -- what did you do with/to the IAT sensor (it's normally fitted in the air intake box near the filter)?

Looks like he fitted it in the underside of the tube, up near the throttle body, above the crossover pipe. Guessing this keeps IAT nice and warm.

I do not own a scanner YET. Only mods thus far, autolite 104's, 180 stat, boost/vac and oil pres gauges in door vents. I have noticed slight differences from my gutted airbox set up and this experiment out of boredom and curiousity. Actually just starvin for HP! lol. This Warm Air device wasnt well thought out. Thank you for your opinions and advice. I am switching back to air box i think. First Ive got some reading to do.

knuckled1 wrote:

I do not own a scanner YET. Only mods thus far, autolite 104's, 180 stat, boost/vac and oil pres gauges in door vents. I have noticed slight differences from my gutted airbox set up and this experiment out of boredom and curiousity. Actually just starvin for HP! lol. This Warm Air device wasnt well thought out. Thank you for your opinions and advice. I am switching back to air box i think. First Ive got some reading to do.

I think your airbox device *was* thought out, inasmuch as you assembled found parts to do a job you wanted, and you should pat yourself on the back for the effort and actually completing the work. It was not engineered--that's where the scanner data and such comes in, and that's what will make the big difference for you. Gotta give you proper respect and acknowledgement. You tried, and for many that's at least 105% of the struggle so to speak.

That said - now that you've noticed you're starving for HP, I hope you're planning to read about putting in a larger downpipe and other mods that are outlined on this site. I think there was a thread that summarized the HP-increasing mods in order of cost/difficulty but I can't find it. AA or Karma might know where it is. And while you are at it you might want to read the thread about "calling out" Alex.

Albertj

Lol. Thats why I came to this site. It was fun for me and I learned a little bit more about MY car. Jugglin projects right now too. Thx again, and I appreciate the direction and guidance from those willing to respond. I have done other minor mods,stereo,amps,subs,door and deck lid speakers. Replaced many,many parts just to keep this car lookin the way it does. I have replaced almost EVERYTHING! lol. Do it again too if I had too. That list would be great. Im about to change SC nose cone this weekend. Waiting on coupler, got rebuilt one but has stock coupler. Noticed the "bastard" pulley squealin couple days ago, cant wait to do that again. Put used one on last time, wont cut corners on this one again.

IAT is located closer to filter end on underside, tried to keep it away from exhaust best I could on the fly. Actually your right it is a bit close to TB and crossover. Is there a way to insulate crossover pipe? Sensor really should be as close to airfilter or air box as poissible, didnt notice this till you mentioned it. Thanks,I think? Lol.

Sure, you can insulate the tube, but some of the heat is soaked directly from the TB itself (there is 200ºF) coolant circulating through it). The heat from the coolant just conducts right through your rubber adapter and into the tube, and to your IAT sensor.

They make throttle body spacers to block the coolant and insulate from heat soak, but I don't see much value in these. The intake air, if drawn from a cool place, passes through the filter, tube, and even a warm throttle body without being heated very much. What little heat is absorbed by the air is actually helping to keep these intake parts cooled.

You want the IAT sensor to read the air as close to the actual intake air temp as possible. Ideally, it should be located right inside the filter cone, or in the tube a few inches downstream. This way your IAT sensor will not soak up heat as much, and your readings will reflect the air, not the temperature of your TB.

It is also permissible to mount the IAT sensor on the outside of the filter, although you may read higher temps from the exposed engine bay (which your intake is breathing, so technically accurate). This idea works best when you construct an air box around the filter/intake area to seal off the high temp air from the bay. Of course, your sensor will be reading lower because your intake is actually breathing cooler air - that's the whole idea!

Makes sense. Thank you Aaron. Workin on that airbox today.