You can post them if you like, especially since everyone is so sure that it’s wrong.

Even though that same cam(and a bigger one) has already gone mid-11’s in a similar combo.

A cranking compression test would help shed some light on that situation.

Yes, both the intake and 800 carb were run on the engine on the dyno.

I feel that the converter was not flashing at 3500rpm but, not too much lower.

Correct, the xe274 cam is not really set up for stock manifolds but, I wasn't unhappy with the results when I tried it. About what I would have thought.

The headers will not be going back on as I'm interested in the FAST class, I've been making changes to move in that direction.

The fuel delivery issues are up on the list of things to check.

This is more a general question, do the F.A.S.T guys dyno their engines with their exhaust manifolds with part of the exhaust?

my quickie guess is the engine is in the process of eating the fuel pump push rod. that would account for the majority of power loss. just a first place to look guess.

I can tell you one thing...Dynomax Super Turbo mufflers are great for a nice mellow sound, but flow like garbage. Get a straight through style muffler.

yes with the ones i have seen.

So in a nutshell changes are

Ported factory intake instead of the RPM
Manifolds with Super Turbos instead of headers and Flowmasters
Custom cam instead of XE274
800 AVS instead of 850 HP Holley

Assuming you don’t have a fuel supply issue, if the cam is right and you’re determined to make it work with the manifolds i’d try the RPM again with the 850. Maybe your ported intake doesn’t work that well. If it picks up alot try the AVS to see if it likes it or not compared to the Holley.

I also think Super Turbos aren’t a great choice, but not sure if it matters with the manifolds or not. Thats where I’d go after the intake if you’re determined to make it work.

how much could the exhaust manifolds be ported ?
if that is a possibility, do the FAST guys do anything in addition to having that gritty stuff [i forget the name] pumped through them ?

My 108 mph, exhaust manifold Charger lost about 4 mph with one failed Super Turbo muffler.......twice.

One of my old street and strip drag cars would pickup .9 ET (12.23 with them on and 11.39 removed) and 9+ MPH (109.4 versus 117.8 with them off with no other changes ) by removing the 2.5 inch pipes with the old Turbo muffs with 2.5 inch O.D. tailpipes that exited in front of the rear tires on my 1969 Dart GTS 440 powered
My Duster had a set of the cheaper crimp together Magnaflow 14x7x 3.0 inlet and outlet oval muffs straight through with perforate pipe, it ran 7.01 ET in the 1/8 mile with them on and 6.98 with them off Those muffs were mounted behind the rear end between the 1/4 panels in rear sub frames. That really surprised me and impress me I can't find them anywhere to buy them now

thinking about all this i have to wonder if the ultimate goal is a FAST engine then all of this irrelevant. i can't think of anything here that would apply to a 500cube high compression purpose built engine. if fast is the ultimate goal then i'd leave all this behind and move on to the challenges of a more sophisticated goal. just my thoughts.

Two replies I’ve seen on here that bare looking at. First is the fuel pump push rod. I had this issue with mine. Only lost .125 but killed a ton of speed. Second is the turbo mufflers. Not a good choice for flow especially with a 500” engine. I switched from Pypes Street Pros to their Race Pros and picked up a bunch.

Bill

The F.A.S.T. guys that are serious I imagine would ?

I'm in the process of restarting my F.A.S.T. build and when it goes on the Dyno it will be with the manifolds I plan to run. I'll also bring my headpipes and a second shorter set if the ones I plan to run won't fit the space allowed.

There are things one can do, port matching is a must. The last set of stock manifolds I tweaked for a friends build needed at least an 1/8" of material ground out of the port entrances on at least 2 surfaces to get it to match the gasket.

I have a set of reworked A body 383 manifolds that have had as much grinding as can be down withOUT cutting them in half and a piece welded in place where there was an internal divot to clear the flange bolt install. The divot was removed , welded from the outside and the flange tapped for a stud instead of the bolt. After all the work was done they were Jet Hot coated inside and out, I don't know if they were extrude honed. The manifolds were done by the late Greg Gessler.

I am going to try to compare them to an untouched set when I dyno to see how much it picks up.

I did.

Bill

Crap. Another good one. Sad and sorry to hear

Same here. Greg Gessler did a pair of exhaust manifolds for my FAST 70 Nova small block car.

This is the first I had heard of his passing. RIP Greg.

-> Greg Gessler obit <-

that's very impressive!