Strip Dominator on stock displacement engine

I have one with a Demon 650 DP (no choke) on a .020 over 351C with a Crane "Hi-Intensity Hyd. Boss" cam, 4V closed chambered heads, Duraspark ignition and a Mind Train 2.5" exhaust system (not a shred of fibreglass packing left-she rumbles).

The engine starts instantly, hot or cold, idles patiently, and pulls hard all the way. Never stumbles or stammers. Particularly nice at 65 mph when you downshift from fifth to fourth and lean into it.

She'll get 19 mpg if you keep your foot out of it.

Gotta admit that sounds much more positive than what I anticipated! Definitely worth considering...

> Is anyone running strip dominator on stock displacement, stock compression
> engine with mild cam? How do you like the part throttle behavior? Tip in
> response?

Tim Tullio got pretty serious about intakes and did a bunch of road and
drag strip intake testing with his Pantera. The engine consisted of an
Erson hydraulic flat tappet cam (232 deg duration @ 0.050", 108 LSA,
0.545" lift), Rhoads lifters, 4V quench heads, flat top pistons, 735
Holley, coatings, C&A rings, MSD ignition, wrapped headers, and MPG
Stinger exhaust port stuffers. Intakes tested included an Edelbrock
Torker, Weiand Xcelerator 4V, Offy Port-o-Sonic 4V, Holley Strip Dominator,
along with a couple dual planes. Tim spent a lot of time optimizing the
carb for each intake. Tim reported the Holley Strip Dominator was 4 tenths
quicker in the 1/4 mile than the Torker and had, by far, the best driveability
(smooth with no flat spots) of the single planes. He said it rivaled
the dual planes down low, as far as driveability was concerned, and by
3000 RPM was pulling away. Unfortunately, he didn't have access to a
Blue Thunder high rise dual plane for those tests. Also, the Edelbrock
Performer RPM Air Gap was not yet out, nor was the TFS single plane.
Tim said he was unable to get some of the other single plane intakes
(like the Torker) to smooth out at lower RPM, despite a lot of tuning time.

In my street 351C dyno testing, the area under the curve for the Edelbrock
Performer RPM Air Gap and the Holley Strip Dominator were fairly similar.
Shifted accordingly, the acceleration the intakes provide would be
similar but the manner in which they provide it would be different.
The Holley would pull harder at higher revs and the Edelbrock at lower.
It's pretty much a matter of preference. Some people like an engine that
pulls hard in the lower revs, others like a power delivery that rises with
rising RPM.

One possible discriminator carb heat. The air gap intakes (single or dual
plane) don't provide for carb heat but the Blue Thunder dual plane does.
Out-of-the-box, the Blue Thunder didn't do so well but with some flow bench
work to bring the 4 bad runners up to match the four good runners, the
Blue Thunder works very well. With aluminum aftermarket heads, carb heat
isn't an option so wouldn't be a discriminator.

One area of testing I'd like to pursue is smaller port single planes
(Holley Street Dominator, Weiand Xcelerator 2V, TFS, Parker Funnleweb)
on 4V heads. I've not run any of those on the street but experience on
other engines suggest that a good small port single plane intake can work
very well on the street.

Dan Jones

quote:

Originally posted by larryw:
... idles patiently, and pulls hard all the way. Never stumbles or stammers ...

Notice he wrote his 351C 4V pulls hard all the way and never stumbles.

A 351C 4V with throttle response described as pulling hard!

The ports are too big my arse!!

quote:

Originally posted by Cowboy from Hell:

Notice he wrote his 351C 4V pulls hard all the way and never stumbles.

A 351C 4V with throttle response described as pulling hard!

The ports are too big my arse!!

...I'll Back that UP!!
I've had Aluminum 'Small' Port Heads sitting in My shop, for Years, ready to go on the Cleveland...But I can't bring Myself to install them! Because I Know, I WILL Experience a Huge Drop in Power!!
'It' is NOT About 'Velocity'! It IS about 'Volumetric Efficientcy'! Deep Breathing!
You CAN build over 700 HP with the Cast Iron, Closed Chambered heads in Combination with the 'Correct' Componants and Proper Machine Work! If You can handle the extra 75 Lbs. over the Aluminum.
The 'Feel' of a Quicker Throttle Response Does NOT Equate to Higher Levels of Horsepower and Torque!! That's My Opinion.
Huge Ports Forever!! And I Don't care How Much 'They' Weigh, a Lot More Weight has been stripped from elsewhere, on this Pantera.

I Will get the Machine through the Curve!...

> Notice he wrote his 351C 4V pulls hard all the way and never stumbles.
> A 351C 4V with throttle response described as pulling hard!

Hard is relative.

> The ports are too big my arse!!

For most uses, including the power levels that you advocate for the street,
the ports would work better if they were smaller. Larger ports mean slower
velocity and slower intake flow port flow is more susceptible to reversion.
Momentum is the product of mass and velocity. If the velocity is low, the
momentum is low and may not be able to overcome the rise in pressure that
occurs when the intake valve closes which allows reversion flow (from the
cylinder back into the intake tract). A low air speed also implies a weak
pressure wave action (and subsequently weak resonant tuning).

There are waves that travel the length of the intake tract. The frequency
of these waves are a function of the runner length and cross-sectional area.
Note that these waves move within the intake (and exhaust) flow. Depending
upon their direction, they can either aid or hinder flow motion. One
characteristic of an finite amplitude wave is that when it hits an abrupt
area change (such as a runner opening into the plenum in an intake manifold
or a primary pipe ending in a header collector), it will change direction.
So an expansion wave moving up the intake tract will change direction when
it comes to the plenum opening changes and become a compression wave heading
towards the intake valve. By timing (via the valve opening events, intake
runner length and cross-sectional area, header lengths and diameters) the
waves can aid in cylinder filling on the intake side and cylinder evacuation
on the exhaust side. Get these events right and you can certainly have
volumetric efficiencies of over 100%, especially near peak torque but also
near peak power.

There's a reason Engine Masters competitors like Kaase and Storlien shrink
the ports of their heads to match the RPM range and displacement. There's
also a reason why Ford engineers made the ports smaller from 4V to A3 to B351
to C302. For a given engine configuration, it is reasonable to assume there
is an optimal timing of the wave harmonics which would also determine an
optimal runner cross-sectional area and length which imply an optimal velocity.
This cross-sectional area would only be optimal for one RPM and perhaps its
harmonics so picking the area needs is a compromise for the RPM range desired.

Dan Jones

Hard to argue that just right wouldn't be just right.

If you think about passenger car (street tires) performance engine at 351cid, and what you have is not optimal port size and flow, would you err on the small side with not enough flow and cross section, or big side with too much cross section and enough flow?

I'd take the Cleveland approach. If it was small four banger, I'd think twice about that decision.

Anyway, it was the 4V single plane, part throttle experiences I was interested in this thread and appreciate everyone's contributions. Seems more viable option for me than what I anticipated.

More inputs are, of course, welcome.

Whether or not it is accurate, I had heard that the 4v intake port was designed for a 370 cubic inch engine.

According to the original catalog listing for the A3, B351, and C302, the A3s are a tad large for my 357. I suppose my compensation for that is just to drive the car at a higher rpm?

I did try a set of the B351 heads, cleaned up in the intake ports and found them disappointing. The A3s for my liking were right on it.

I do have a feeling though that the definition in this case for "optimizing" the ports has to do with total area under the curve and not necessarily peak HP, that might be where I felt the difference?

For me there was no point in increasing the wheel spin off of idle with smaller ports. A little torque kill in the right parameters can be a good thing I think?

So the Holley intake works by increasing port velocities on 4v engines? Does it do that by maintaining flow rates with increased velocities?

Wouldn't that intake need to be tuned to a specific camshaft profile to work?

Hum...wait a minute, presuming the ports mismatch to an A3 could be worked out, would it work on an A3 head too?

How much you want for that manifold?

> I had heard that the 4v intake port was designed for a 370 cubic inch engine.

A formula for the required minimum port area in square inches is:

Amin = (RPM * Stroke * Bore * Bore) / 190000

This formula is based upon the fact that volumetric eficiency stops increasing
at around a port velocity of 0.6 Mach.

If I did my math correctly, for a 7000 RPM 351C, that works out to 2.06 square
inches. A 4V intake port is approximately 2.5" tall by 1.75" wide which is
4.375 square inches. Under the valve seat, I've measured from 2.37 (untouched
with considerable casting flash) to 2.79 (cleaned up) square inches. Only a
small taper area is benficial so that huge mismatch doesn't help things.
I've got a set of C302B's from Alan Kulwickis shop from back when they were
making in the 750+ HP range with a flat tappet 358. The ports aren't terribly
large.

> I suppose my compensation for that is just to drive the car at a higher rpm?

While they work better the higher the RPM, they will still be oversized unless
your idea of higher RPM is Pro Stock territory.

> I did try a set of the B351 heads, cleaned up in the intake ports and found
> them disappointing. The A3s for my liking were right on it.

Heads are one part of a combination. Without knowing everything else about
the combination, you don't where to pin the blame. Perhaps the cam, intake,
headers or some other part you chose was better suited to the flow characteristics
of the A3's. Local circle track racers prefer the smaller port C302's to the
A3's because of the better throttle response. That's not to say the A3 isn't a
great cylinder. The 4V closed chamber head is a pretty good head, especially
on a larger displacement engine and the A3's are superior to the 4V's. In practice,
it often comes down to the particular head characteristics or the particular
combination of parts. I had planned to demonstrate this by testing several sets
of small and large port C302's and ported/unported A3's on my 403C but the dyno
is broken. It's not clear when the dyno will be back on line (repair parts no
longer available which required an upgrade and an adapter which is on back order)
nor when I'll be able to get back on it. If my white Pantera is ready before then,
that test will have to wait for another time.

> I do have a feeling though that the definition in this case for "optimizing" the
> ports has to do with total area under the curve and not necessarily peak HP, that
> might be where I felt the difference?

Possibly. If the engine made less power in the low and mid range, the
top end might feel stronger by comparison, even if it wasn't. The right size
ports work better across the RPM range but the difference is less as the RPM
increases.

> A little torque kill in the right parameters can be a good thing I think?

It will take a bunch of RPM before you get back to parity, much less make
better power if the head ports are considerably larger than they need to
be.

> So the Holley intake works by increasing port velocities on 4v engines?

No. The Strip Dominator has 4V ports.

> Wouldn't that intake need to be tuned to a specific camshaft profile to work?

It's always best if all the parts are tuned to the same range.

> presuming the ports mismatch to an A3 could be worked out, would it work
> on an A3 head too?

The Strip Dominator has 4V ports so you'd need to weld or epoxy the intake
manifold port floors.

> How much you want for that manifold?

Who are you asking?

Dan Jones

The intake port of a 302 is 1.94 x 1.04. That's an area of 2.01.

You say 2.06 is correct for a 351c at 7,000rpm?

With all due respect to your formula, consider me a non believer and leave it at that. That is absolutely ridiculous. Period.

> The intake port of a 302 is 1.94 x 1.04. That's an area of 2.01.

and if that were the minimum port area of a 302 head, it would be
relevant but it's not. The minimum area is typically just under
the valve seat or at the pushrod pinch.

> You say 2.06 is correct for a 351c at 7,000rpm?

That is the minimum area to keep the Mach number under 0.6.
It is a minimum that assumes an ideal valve discharge. In
practice, the area needs to be somewhat larger (factored by
the valve discharge coefficient). An inefficient head can
have a discharge coefficient considerably below 1.

Dan Jones