Header Size Question-3.2 Carrera heads
 

Looking at a set of Black Friday priced B & B headers for my Proto Motive 3.3 Turbo motor. Because of the 3.2 Carrera heads I am assuming 1 3/4 inch primaries instead of 1 5/8 inch. Correct? I sent a message to B & B yesterday but never got a reply.

Turbos require velocity and heat for power. To optimise power the primaries should be the same size as the exhaust ports. Carrera ports are ~39mm so the ID of the primaries should be as close to that as possible. Our 1 5/8" primaries have an ID of 39mm which we use for this application.
You get what you pay for with headers. The balancing act of quality and design vs economy. We build custom for the application and use the right alloys for the job.

Just curious, you found 1 3/4" headers for sale? BB makes them?

Go with the bigger ones for the kind of upper rpm range 550 HP power you're after with those heads.

Yes bb makes 1 3/4, I had a set once. I believe Brian also makes them, ck him out.

I went from 1 5/8 to 1 3/4 on my 3.2 back when it had the supercharger and it lost a ton of bottom end power. Put the 1 5/8 back on and my car was back to normal.

When looking at the B and B line up the 3.2 Carrera non-turbo headers were 1 3/4 and the standard 3.3 turbo headers were 1 5/8. I made the assumption that the 1 3/4 would be a better fit for the 3.2 heads. Maybe I was wrong? The price was hard to pass up but will not get the technical assistance that could have been offered by RarelyL8. I do not want to lose bottom end.

I have 1.75" primary's, worked Carrera heads, and have a problem with too much bottom end/wheel spin. I'm going to my 3rd set of cams this winter, moving up to 993SS. I have no problem lighting up my 315's which creates a problem at times. Philip

What mm are your ports opened to? 45?

44-45mm.

Nice. What power are you making? Spool times and turbo?

Interesting cam choice.. I have a set of these on the shelf as well. They are going into a N/A 3.0 CIS build in the next few weeks.. should be interesting to see how they perform.. from what I understand, this is about the limit for CIS.


What cam are you running now? Are you changing out in an attempt to cure what you've stated above, or moving from stock or SC to the 993SS?

I'm running Elgin 330 cams now. Timed at 1.65. I still cant use 1st gear with more than 1/2 throttle with out breaking loose. trying to move the torque higher. Philip

You should't just look at the headers / manifolds as a isolated part. You must look at both individual part / item as well as the overall design of the system. Sometimes you can get a good result from playing mixi-match, othertimes this can yeild strange or un wanted side effects or yeild disappointing results across the powerband and diminish response etc...

There are a number of factors that will play into what is the best exhuast design, ie the best design for you. You need to really understand the overview behind the R & D behind the perspective firms product you want to go with. Often time the customer is all excited off a prospective number, not realizing this figure could be based on a vehicle with mild power plant work or heavy up grades or operating at much higher boost pressure levels. Much will depend on what the system was designed to yeild.

Depending on what you have done engine, the combo of bits and goodies, etc can really
effect what you need.

The physical header design and how that design functions with supporting components both in isolation and in conjunction. So, you can get some ideas here. But it's just that. Ideas.

I will say this, besure that the waste-gate is up to the task of controlling any up grades, and besure to size it correctly.

Happy belated Thanksgiving everyone and enjoy all Christmas shopping chaos to come!