Thread: Custom headers and some questions

I will be up for a custom set of extractors to get to my power goal. I want to make at least 800 hp aspirated from my 532. Exhaust valve size is about 1.8" from memory, and the exhaust shape is BBC.

Here are my questions:

1. Should my primaries be the same length the whole way or stepped?
2. How long should the primaries be?
3. What size collector?
4. Does HPC really help bring down temperature and make more power? I think street fords quoted for every 50 degree temp drop you make 10% more power so that would be at least 50 - 80 hp for me.
5. What size should the rest of the system be?

Thanks.

Prob a lot more qualified to give you exact specs than myself but here's my 2c worth. There are some programs available to give you exact specs .
1. As close as possible to same length
2. 2-1/8" primaries ,length ? .Daimeter of pipes are going to be limited some by the vehicle they are for .
3. Merge collect 3.5-4"
4.A definite yes to HPC even if not for exact gains from the coating on the pipes but cooler engine bay temps will increase power.
5. 3.5-4" system with X-pipe.

Greg, will i get away with my twin 3" system with the cutouts?

I will still be driving it on the streets and its already pretty loud. Can i use the cutouts when im at the track to mimmick the twin 4" system? They are 4" exits.

Ill try and find an exhaust program online.

Guy i spoke to some time ago said twin 3's were good for 800HP . No harm trying it for sure . The cutouts will help .

Ive been reading plenty today.

Ill have a read of those now Greg.

I ran your engine thru pipemax to get the pipe lengths/diameters for you but I have only guessed on some of your specs...

If you could, please post your:

Bore:
Stroke:
Rod Length:
RPM where you make the power or rev limit:
Compression Ratio:
Valve sizes I/E:
Cam Specs: Duration/Lift/LSA/Centreline

Click the thumbnail and check out if I'm close on the specs:

Bore - 4.44"
Stroke - 4.3"
Rod length - 6.8"
RPM range - max 7000 rpm
Comp ratio - 12.9:1
Valve size - waiting on the heads to come back but i BELIEVE the valves will be 2.3" intake and 1.82" exhaust. I think! :P
Cam - yet to be chosen - maybe retaining mine or regrinding it if possible.

Where can i get that program?

I'll do another run with these new specs when I get back from work.
Its Pipemax by Larry Meaux, I bought it off him via his website... Great little program, aside from exhausts it also calculates required cross sectional areas, CFM requirements.

Its not free, but not expensive and in my opinion worth the money.

Have a read of what it does here:
PipeMax36xp2

Did up another one for you, I guessed the cam specs, but the program works more on the Volumetric Efficiency/Engine size and RPM anyway.

Thanks for that. Its about what i was expecting.

Can someone explain what the line " Best hp/tq tuned collector length " means?

It means you will make the best horsepower/torque with that length/ diameter collector

In that example it tells you to use a collector that measures 16.8" long measured from the END of the primary pipes... The other numbers: 33.6, 67.1, and 134.3 are the collector lengths that will also work, also measured from the end of the primary tubes. Basically anything after the primaries can be looked at as a collector. Use a standard collector style,no need to spend $$ on the merge collector fanciness.

So, if you have a full length muffled exhaust system I guess you could use the 134.3" for the length of the system. Run an X-Pipe in the middle at 67.1".

Its gonna be loud even with 3" pipes and mufflers mate.. If you dont have mufflers already take a look at the magnaflow range which is a nice sounding muffler with not too much power loss.

OK i couldn't work out what the high inch numbers meant. I thought it was after the end of the primaries but couldn't savvy the 134 inches.

Yeah loud tell me about it. I already have the twin 3" system. Can't say im a fan of X pipes. I had mine removed because i disliked it that much.

Thanks for the help. Anything else you want to add im happy to hear it.

Just touching back on this topic, for the primary section, is it better to use the same sized primary, 2 step or 3 step primaries? What are the advantages and disadvantages of each?

what did your head porter recommend ?