Headers

[SappySE107]

Putting the fans in front will require something to compensate for going through the AC condensor (i think). A slim fan is the best bet. That or just run a primary fan. I want to run the front headers over the trans, and some creative bends to make up the length (not too sharp). Having a 5 speed means there may be more creative freedom for the rear primaries.

John used 1 3/4 or 1 7/8 inch since he was planning on supercharging his engine. Who knows if that ever got done...he disappeared from the forums.

[Anonymous]

Im not too sure on the AC condenser needing that good of air flow over it or not... it would be worth looking into.

John, I think, has disappearing because he knocked up his g/f and the baby was probably born fairly recently... not entirely sure on that. I see him on AIM everynow and then, but other than that I never see him post. He probably doesnt know whats going on w/ all the forum switches lately.

As some of you know, John ran six tenths faster in the 1/4 mile and a gain of like 8mph with those headers. (He went from a 14.9 to a 14.3)

[Anonymous]

Screw low end!!!

love the 5-speed.

anyway i will probably want a 2 1/4" collector that way i keep all the high end since the 5-speeds dont really need the low end(on the track at least) I am undecided whether to run them in the stock location or go under. Going under will give more of a possibility for equal lengh, but harder to do.

also, with 48" lengh, there might be enough to run the primaries, the front 3, side by side under the car, then have them collect near the rear axle, there is ROOM there cuz i dont have a bigass POS tranny there .

This sounds bettter, closer to equal length too. Then run the 2 1/4 straight back, off to the passenger side.

for the back 3, run them in a trianglelated shape(not collected) for 48" down the stock setup, then collect them and run it to the driver side.


By doing this, we get headers, close to equal length, and we get true duals. this sounds liek a good plan, even tho the exhaust would be pricey, 2.25" mandrel bends(X2), 2.25 muffs, cat, and res(all X2). damn. And i cant reuse my old stuff, its all 2.5.

Do the headers have to be mandrel bent?

If so, we can go through Shane(redzmonte), he gets good deals on mandrels.

[brian89gp]

Why would you want true duals?

And as far as how I think, the stock fan behind the radiator blocking air going through would be the same as a fan on the front side blocking air.

[Anonymous]

True Duals offer more performance gains than Y-ing the pipes.

what are you talkign about on the fans??? we dont care if they block air, they are just in the way of the headers. But if we move them to in front of the radiator, they can push air through and get out of our way.

[SappySE107]

well, pushing air through a restriction causes deflection. Im not worried about the AC performance, im worried about it restricting flow from the push type fans. Actually I dont care, im not using push type fans.

[brian89gp]

True Duals offer more performance gains than Y-ing the pipes.

Then you must go through the pain of making sure that each bank that the collector to tip distance is the same and has the same back pressure and flow restrictions. Or I say you should do this.

what are you talkign about on the fans??? we dont care if they block air, they are just in the way of the headers. But if we move them to in front of the radiator, they can push air through and get out of our way.

Same as placing a sheet of cardboard in front of the radiator, if you do not have enough air to cool the radiator then you are going to be overheating all the time.

[Anonymous]

Then you must go through the pain of making sure that each bank that the collector to tip distance is the same and has the same back pressure and flow restrictions.

No you dont. doesnt matter if they are the same lengh cuz theyre just going out anyway. and if they are the saem size with the same bends and the same muffs, etc, then theoretically b.p. should be the same.

Same as placing a sheet of cardboard in front of the radiator, if you do not have enough air to cool the radiator then you are going to be overheating all the time.

thats whent he fans turn on, therefore pushing air through the radiator to cool the water which cools the motor

[Anonymous]

The reason I say use 2" collectors to save bottom end is because with this heavy of a car, you DO NOT want ALL topend. You could go to 2.25" or even 2.5" collectors if you wanted INSANE topend, but how the hell would you drive it off the race track? Shit, I dont know about you, but I wouldnt want to have to dump the clutch at 4k just to get a good 60'. (Even with 2" collectors, you are still going to gain topend over the stock hollowed-out logs for exhaust manifolds )

Aaron, you are confused on the fan situation... Think of it this way: Are the fans BLOCKING air right now, in their stock position? No. If you move them to the front of the radiator, will they block air there? Yes. Therefore, the radiator MAY not get sufficient airflow over it to cool the engine. Understand now? Sure, youre way may work, but wont the engine temp be jumping all over the place? Temp goes up, fans come on, temp goes up, fans come on. PLUS the fans are programmed to TURN OFF over 50mph in the chip because at 50mph there should be sufficient airflow to cool the radiator (and because they cant spin that fast I think). Therefore, with the fans in front, its possible you could have cooling problems at 50mph+.

About running "true" duals... I think it would be a better idea to have the 2" collectors meet into a 2.5" or so pipe then Y off in the stock position. That way, you can equalize the pressure (assuming that the collectors are the same length, does this matter?) and have even flow for both banks of cylinders.

I like the way this thread is going, lots of info being shared. Lets keep the bickering out of this or necks will be wrung!

[Streetrodder83]

Something I have heard, and by no means have I taken it as gods word. Is that a single 3" can out flow dual 2.5". Whether this is true or not I have nothing to offer to prove or disprove this. This is one of those things I heard a few years back, and don't remember who I heard it from. I also don't know if it was in referance to 3" manderal compared to 2.5" crimped. Another you could do Aaron is find some lower profile fans to mount on the backside make a custom bracket to mount them. The fans could cause an issue with cooling out front, you have to look at it this way each blade covers up surface area of the front of the radiator, including the shrouding, if you use that. The potential is there for a negative effect on cooling. You can try it, and see if it works, but don't be disappointed if your cooling is affected.

[SappySE107]

I can change the fan stuff easy enough. Depending on where you live, the secondary fan can be removed. Well, if you get rid of the AC anyway I have no problem without the secondary being plugged in, but that is only test it from 70 degree days too. I doubt I will have an issue unless I am back in Phoenix.

[Anonymous]

Ya, Im not worried about the secondary fan really either. Ive NEVER had both fans come on. The only time the secondary fan is on is when the AC is on. Would it be possible to change the chip so that the primary fan comes on instead of the secondary fan with the AC? If so, then I could probably get rid of the secondary fan without any problems.

[Anonymous]

Ive heard that the secondry fan ONLY comes on whent he AC is running, but i am not sure. I have never seen mine on either, except when i went to the track up here AND ran my AC, then it was on. I understand the fan thing now. but above 50 there shouldnt be cooling problems, even if the fans are blocking lets say 40% of the airflow, becuz at 50 there is A LOT of air rushing in. at any rate i think i can run the headers with the stock fans if i just take them out and go straight down, but not out too much.

I also like the way this thread is headed, becuz there is defianttely a need for headers.

[bwawuz02]

well i heard that tuning the exhaust to match the intake was the best bet. me and john (KickingZ) had talked about it after he made his first set. that's where i came up with the short runners. but like intake runners the shorter they are the fatter they have to be. plus with 20-30" runners the setup should easily fit inside the engine bay (5spd). i personally think that 40"+ runners is rediculous. maybe on a pushrod motor.

and as for the true duals, H-pipe me baby. also if you've ever seen the exhaust manifolds on a 325i, after they collect they run dual to the back of the car, but in the engine bay the 2 pipes get really close together and the O2 sensor is in where they meet. it's like the two pipes are tangents of each other. hopefully some of you know what tangents are.

[Streetrodder83]

Here is a site you guys might want to checkout http://www.headerdesign.com it has a general overview into some of the considerations for headers, they also have a small program you can use to punch in a few numbers and it will give a basis to start out with for primary and collector sizes. Just something for somewhat of a starting point.