Heres my problem... I just recently ordered MAC Long Tube headers. They are 1 5/8 pri and a 2 1/2 collector. They will be put on my 302. The problem is I just recently decided that in a couple months I want to get a new engine. Its a DSSRACING 347 Pro Bullet Long Block pushing 490-510hp. Will these headers be OK with this set up or should I invest in larger tubes and collector size. And just to let you know I rather stay with a smaller size if they are going to pull more torque. Thank you in advance for all the help.

 

probably want to go bigger on header size, 1-3/4 LT's work pretty good on most medium displacement small blocks in your HP range. 1-3/4 LTs, 28 or so inches long (if your keeping it along a 6500 peak power range) with 3 inch collectors. Pretty standard stuff. As for the rest of the exhaust I would reccomend a good x-pipe and some bullet mufflers.

Carb'd or injected?

 

The car is fuel injected, Im now still not sure what header size I want because Im kind of undecided on what engine i am getting. I was looking at the 347 but I dont think that it is streetable for me to drive. I just dont think that I can afford it so now I im looking at the 306 which is putting out 390-410 depending on the cam that I use.

 

a 347 can very streetable, as long as the pistons can properly support the oil ring (r/s ratio is of little concern here, pontiac's 455 has a worse r/s ratio than a 347)

You can go with an 1-3/4, will still work pretty well (1-3/4 x 30). or a 1-5/8, but the smaller headers actually require longer primary tubes with the same basic rev range.

I dunno if this will help, but

http://www.airflowresearch.com/

hit the dyno tab tests and compare engines to yours, however it looks like an 1-5/8 LT would support 400 hp nicely

 

looking at the website I think that Im going to go with the 1 3/4 because I plan on doing major work and going by the numbers shown on that website It looks like I might need them. But I have one problem, do you think that I can put the 1 3/4's on my 302 before I get my new engine without any problems?

 

As long as it uses a standard Ford exhaust bolt pattern, NP. However the 1-3/4 primary dia is a bit big so exhaust flow will slow down. I'd just wait for the new engine to come along

 

Thanks alot for all the help. I eneded up getting the MAC Longtube 1 5/8; 2 1/2 col. ceramic coated headers with the 2 1/2 MAC Pro Chamber H Pipe (off road- no cats).

 

wow, whos checkbook do you have acess to? I thought you were selling it? So you are gonna keep the stang and put a new motor in it?

 

I go to school and work 3 jobs. Its my own checkbook.... unfortunatly.

 

oic, i was JW, since you were gonna sell it. Too bad you dont have acess to Michael Jackson's checkbook, where hes going hes not gonna need it