Originally posted by Rocky:
Well - everyone has to make trades on the configuration of their motors for various reasons (cost, fitment, etc.)
I am convinced (as is my builder) that Doug is right, and the limiting factor in this build is at the end of those headers.
Does Hall sell Fiat parts?
Most of the disappointment is from the exhaust BUT I've played with that intake and I can tell you that just a Torker is night and day over it.
The Holley Strip Dominator is documented 25hp over the Torker. Not by me. By an ancient magazine article and possibly confirmed by one of Dan Jones dyno pulls? I'd have to re-review those?
What you have in that manifold is a pretty thing but it is the best to use with an automatic transmission, not a manual.
I was running a Holley 4779 with a leaned out idle circuit so it wouldn't smart you eyes at idle.
I think that it is the entire header itself that is the issue. This is ancient technology that the Pantera chassis on "under" headers restricts.
You need a 2" primary tube header, about 36" long primary tubes, and a 3-1/2" collector about 6" long to maximize exhaust contributions.
Simply put, that's a no can do in a Pantera. Not on UNDER the car headers.
Most headers are going to have two long and two short tubes on each side. That's more a function of what the builder can get into the assembly and to get it to fit to the chassis more then desire. Even the 180's are not going to have all equal length tubes to them.
In an early Mustang it is possible to get equal length primaries, or very close to it.
So sure, there is usually a compromise somewhere. I do remember Dan Jones saying that the Blue Thunder intake had 4 ports that flowed well and 4 that didn't and it needed to be reworked. That was proven on McLain's flow bench. Makes sense to me from my own results with it.
To be 100% truthful, I ran the Shelby lettered version of it. It is said that the Blue Thunder is a "continuation" but I can't verify that. I gave up on it 25 years ago. It's a good thing it's pretty, 'cause it sure isn't very smart?
How much power there is to find in the exhaust probably varies from set up to set up, but your induction flow has got to compliment the exhaust. Your's doesn't.
It is probably safe to say that with the right headers, there should be 75 to 100hp hiding and ready to be unleashed.
With a 1-3/4" x 24" long primaries, right there that's a killer BUT just simply changing the collector on THOSE headers is probably an honest 25 to 30 hp gain. I'd do that as a minimum.
The problem is, it doesn't fit well through the rear suspension.
Look at the headers from Pantera Pro-formance. They reduced the collector to 3" for clearance to get it through the suspension BUT it's a real collector and ANYTHING helps. The primaries on their GTS headers are also 2".
If I were you, I'd start borrowing sets of headers to try on the dyno before you settle on a combination. Maybe even a set of 180's to compare the power differences with? Check out Dan Jones dyno's. I know he was working on headers but don't remember how far he got with those tests?
The headers that you have are certainly alterable collector wise. The issue is going to be if it will clear when you put them on the car.
Why don't you let someone else do the hard work and either buy in or copy what they did?
Also a full 2-1/2" exhaust won't hurt either. Those only loose a couple of horse power at the very top rpm's to a full open 3" exhaust. That's not bad at all but 2-1/4 is restrictive.
None of this is your fault. From the very beginning the original Pantera exhaust was a bad compromise.
When 350hp was a lot of power for the street, that wasn't a problem. Things change.http://www.precisionproformance.com/
And just to add on another thread here, I wouldn't be surprised at all that 1.8 rockers show a noticeable increase AND that is a cheap trick as well.
Just be sure that the valve springs can handle that extra lift.
Of course this experimenting would be simpler if the dyno was yours and you could mess with the set up under no pressure to get off of the machine?
So what do you need 500hp for anyway?
That's your dyno in your garage right?