Dyno Questions from a novice

I'll toss out 340 RWHP.

Next?

Larry

I tried to get the cam specs but the 23001 did not come up. My guess is 380 RWHP
Stock iron closed chamber heads?

It is very hard to estimate HP without knowing what intake manifold and compression ratio the engine has but I would guess that the stock exhaust will be a limiting factor.
I would guess 330-340rwhp.


Ron

Stock 4V quench heads. I think my compression ratio is 10.5 to 1, I will dig out my info and confirm. The manifold is stock

I agree the exhaust will cost me the most HP

Anson

Cam is a Howards CAM part number 230041.

Im gonna go with 321.7 . The only reason I have gone so low is that the numbers are almost always lower than people expect. I have seen some fairly potent seeming motors on the dyno that have not performed as expected. It will also depend on the make of the dyno. Have fun and let us know.

With the stock exhaust, I will go with 315 RWHP.

John

Is it a Mustang dyno or a Dynojet?
The #s on the Mustang dyno are usually lower.

Ron

Dyno Dynamics machines are even lower still.

Stock cans cost me 35 rwhp.
Will

Dyno numbers are properly used to tune an engine so absolute bhp is irrelevant. What's done is to make a run, then go home and make further changes and re-run on the same dyno to see which way power & torque moved (if at all).

You've done the first part. How does the car drive? If you're satisfied with it, you're finished. If not, dig in...

Assuming:

393C with 4.03" stroke by 3.85" bore, 6" rods
10.5:1 compression
Hydraulic flat tappet cam with specs:
302/308 degrees advertised
224/234 degrees duration @ 0.050"
0.538"/0.562" lift
112 deg LSA
ANSA mufflers and 4-into-1 headers (not the original factory log style)
Ford cast iron square bore intake
Holley 770 Avenger carb

on a Dynojet chassis dyno, I would expect the above to make right at 300 RWHP @ 5000 RPM,
with torque peak around 4000 RPM. That number may require a 1" spacer under the carb
(open or HVH style, 4 hole standard didn't do as well in our dyno testing on the factory
iron intake). You mention the headers are original. If you mean the orignal log style
tubing manifolds without a collector, you may lose 20+ HP.

Dan Jones

I'm way high on my guess compared to everyone else.
With a 20% loss through the ZF, we get only 360fwhp with 300 rwhp.
What is the motor missing? It's got decent cubes and compression. Cam is not huge but decent, I think?
Heads? Intake/carb?
Dan?
Will

> It's got decent cubes and compression.

Yes.

> Cam is not huge but decent, I think?

The cam is not well matched to the engine and the ramp rate is
very mild.

> Heads?

Heads are not the limiting factor.

> Intake/carb?

The intake is one restriction, particularly if run without a spacer.
The carb should be sufficient for 400 FWHP or so. The biggest
restriction are the ANSA mufflers. We lost 50 HP on a 400+ HP
351C with them. He could see 30 HP with an intake change, assuming
the exhaust is taken care of.

Dan Jones

The numbers are in. The dyno was a Mustang and all of the pulls were consistent. The best was 292. Attached is printout from the dyno.

Dan your prize is in the mail for guessing the closest. I am interested in talking with you about cams. I think I will pursue an upgraded exhaust (Maybe the GTS headers and mufflers) and that should get me over the 300HP mark.

Thanks
Anson

What were the numbers like for the other Pantera's that attended?
Will

> Attached is printout from the dyno.

Would you email me that directly? The attached one is too small for me to read.

> Dan your prize is in the mail for guessing the closest.

I have an unfair advantage. With the Dynomation simulation program and the
data collected on the flow bench along with the testing on the 351C dyno mule,
Glen Hartog's 408C, Mike Drew's 408C and Orville Burg's 393C I can make very
accurate predictions.

> interested in talking with you about cams.

Sure thing. I should be home from Saudi Arabia very soon and would be happy
to talk.

> I think I will pursue an upgraded exhaust (Maybe the GTS headers and mufflers)
> and that should get me over the 300HP mark.

The GTS headers are fine but the GTS mufflers are not much better than the OEM
ANSA. We lost 50 HP on those on a 408C. Mike Drew's modifed versions (cans
gutted and filled with a perforated Y-pipe so no baffles) lost 38 HP on a 351C
versus 50 HP for the unmodified versions. We suspect that the internal diameter
of the tips is the biggest remaining restriction, though it could also have a
reflection off the y pipe.

Steve Wilkinson had a prototype set of 4-into-1 headers and mufflers that will
be available in either mild steel or stainless steel at a very good price (IIRC
$1200 for the stainless set of headers and mufflers). By the constuction (the
super thick flange is the tip off), I believe OBX is manufucaturer. The mufflers
look externally like ANSA's but are modified internally and have a larger ID in
the tips. Steve said they picked up something like 25 HP over the ANSA's. He
seemed willing to lend a set for dyno evaluation once they are in production so
I hope to test them.

On most Pantera headers, the collector internal diameter is only 2 1/4" and is
very short. I expected this to be a major restriction but the dyno has shown
it's not that bad. Testing against a set of long tube headers with 3" diameter
collectors has shown the Pantera headers do give up some power in the lower RPM
ranges (due to the short primary lengths) but the horsepower difference at the
top end is small. As I've mentioned before, the mufflers are the major
restriction. We've been testing 3" inlet/outlet straight through Magnaflow
mufflers with a 3" diameter intermediate pipe clamped or bolted (depending upon
the headers used) to the headers. I'd like to also test 2.5" intermediate pipes.
I suspect those will not show much of a penalty compared to the 3" diameter since
the collector diameter is smaller. Then I'd like to test the 3" inlet, dual
2 1/2" outlet Magnaflows to see if they work as well as the 3" inlet/3" single
outlet vesions. THere is a possibility there is an adverse reflection off the
internal Y-pipe. If that's the case, I'd expect to see dips at particular RPM's
but not across the entire RPM band. 2 1/2" inlet mufflers might even be
acceptable but I'll have to contact the muffler manufacturers for pressure drop
info to know for sure. My guess is that a 2 1/2" intermediate pipe feeding a 3"
inlet muffler would not lose any power the a 3" intermediate pipe. I run similar
Magnaflows on my daily driver '87 Mustang and like them quite a lot.

Flowmasters have a reflection problem that makes them sensitive to placement
(distance to from the collector to the muffler). Closer tends to be better so
maybe not a big problem in a Pantera.

Mike McDougal has posted on the Cherry Bombs he uses. I didn't get a chance
to dyno those but Mike reports they made a noticeable difference.

Dan Jones