I cant find any good setups on firebirds, but how big is too big? It seems if I run all 4in it looks kinda massive under the hood. I was thinking a 4 to 3.5 elbow, 3.5 pipe to a 45* then having a filter infront of the coolant tank. Thoughts? 3.5in big enough? I would love to run the factor setup but I know it would kill power as it lost 12 RWHP when I had my SBC setup.

 

Mine's 4" throughout and it's a Firebird



Pretty basic. I planned on running it below the battery tray but just did it like that for now.

 

4 inches pile! 4 inches! Mine is a firebird also and it is overkill but it looks awesome in my opinion.

http://i225.photobucket.com/albums/d.../wiring102.jpg

 

3.5" should feed majority of motor needs under 500hp or so.

 

If you're running the 85mm (3.35") MAF, just go with 3.5" piping. No point in going bigger since the MAF is the restriction.

 

Stock throttle body is just about 4 inches o.d. Stock maf for trucks and aftermarket mafs are 4 inches also. Using 4 inch piping makes connections easy. No reducers.

 

Its actually closer to 3.75" for stock LS1 TB. You can buy silicone 4 to 3.5 and 3.75 to 3.5 reducers to make it easy. I have 3.75" to 3" on my LS1 TB

 

Heres mine. 4" all the way



I must have a wierd TB, it measured 3.9" OD. The silicone couplers come in just under 4" ID so its a snug fit, I didnt have to clamp it down much

The truck 85mm MAF on the other hand has a 3.9" inlet and 3.7" outlet which I couldnt compress a 4" coupler down to. Luckily the air filter came with various diameter rings that put the OD back up to 4". Wrapping it with several rounds of electrical tape would also work for a ghetto rig

 

3.75 was a SNUG fit to get it on but 4" was pretty loose... it may be 3.8-3.9". I will check my 99 TA real quick...

I stand corrected I guess...My TA is closer to 3.9" or so. I tried a 4" coupling on the TB on my camaro which is suppose to be from a LS1 fbody, and it was pretty loose and I wasnt sure if it could snug down.. So i got the 3.75 one and it was very snug but did slip on...Its about as tight as a 4" ID coupler on a TPI 58mm throttlebody ovaled out..
So not sure if there was a difference in TB's over the LSx cars other than the throttle spring style, or maybe I got a truck one? Not sure. Looks like 3.75 and 4" could work for either one.

 

There ya go O.P. 3.75" all the way!

 

I was thinking internal diameters.

Hey Pocket, did you make make that pipe or buy it?

 

Made it from 4" mandrel bend exhaust tubing

One 90* leg cut short and one 45* cut in half

 

Might have changed a bit throughout the years, Mine's is like Pocket's. My 4" rubber elbow fits nice and snug overtop of the TB.

 

No MAF here. Running a SD tune for now. I see the 4in to 3.5 elbows so I may go that route.

 

I have used these guys for all my intake coupler needs. They make all kinds of bending reducers as wel as regular couplers. Some 3.5-4" exhaust pipe can be bought, cut and easily pasted into the engine bay. How I made my 3.5" CAI
http://www.siliconeintakes.com/

 

To bad no one makes 3.75" aluminum tubing. That is about as big as I can go in my car. I will check the KPA on my next dyno session to see if my 3.5" tubing is still flowing enough air.

 

3.5" tubing can flow a ridiculous amount of air...

 

"3.5" tubing can flow a ridiculous amount of air..."

I am hoping enough to support say 550hp. With bends etc there are losses to the air flow and I don't want the total accumulation of losses in the whole intake tract to be less than what I need. I would like more of a safety margin. I have been monitoring the LSx boards and it seems they are going to 4". If my KPA in the plenum is in the 98 to 100% range than I feel I am just fine.

 

Pipe size is one thing, but the filter will be the most restrictive I think... you need to get that large enough to pass the air...

However based on how my turbo car runs with and without filters installed, and i have rather small 3.5" inlet filters by AEM, I think they pass alot more air than most will need. So a good large sized 3.5" filter should do well for 550 hp.

Most carb systems pull a minor amount of vacuum and make most power that way. I wonder if EFI will work in a similar manner?

 

FWIW, here's mine (Camaro, though):




4" to 3.5" reducing elbow, stock LS1 MAF, 3.5" rubber coupler, 3.5" aluminum tubing, 3.5" 45 degree elbow, AMSOIL 3.5" EaO cone filter. Except for the filter, I got the parts from www.intakehoses.com, including the T-bolt clamps.

 

Mine is run pretty much the same way. Finding the couplers is the hard part. It's like I can't find anything other than 2.5" couplers or 6" couplers lol.

I DID run it right off the TB, I just used a coupler to put the maf on the end of the tb, and then slipped the filter over the end of the maf. It's a shallow/short filter, but it works well. I will probably go back to the elbow set up when I relocate the battery and clean up the engine bay though.

 

I used those guys for mine

 

Is this a K&N kit or did you piece it together yourself?

 

Pieced it together myself lol. I got a K&N sticker with the filter so I put it on there. It's 4" aluminum tubing painted black. Everything came from intakehoses.com (other than the filter)