440 source heads real world numbers

When I swapped from my 915 to the normal 440 source stealth heads my car picked up .2 in the 1/4. From what I've found online researching is the basic stealth heads flow around 268 cfm and the CNC version flow around 320ish. I have no idea what my old 915 heads flowed, they were pretty stock with a home port job done. Has anyone swapped from the reg stealth heads to the CNC version? Just curious as to how much I may be able to pick up with the CNC version heads. I'm looking to build a stroker in the future, but don't have all the coins at once to build it, so I thought maybe upgrading my heads now will be one less piece I need down the road.

I don't have an answer for you, but I would be interested in knowing, as well. I have a set of Stealths on my Bee.

I have the CNC'd Stealth Heads on my '69 RR. 4.30 gears, 3800 RPM converter. M & H 275-60-15 stickies, and SS springs. I had one track day at Maple Grove where I made 9 passes and a bunch of changes. When finished, the best pass was an 11.62 @115MPH. My 60' times increased by a tenth over the best pass ever.

The engine is exactly the same as the one I replaced, except it's now a stroker with the Stealth Heads. The first engine was 440 CI with Ported 452's that had 2.14/1.81 valves. That engine ran a best of 11.54. Don't remember the MPH.

I believe there is some more to gain with the new combo and some tuning, but the overall gain was not what I expected. The good news is the heads look stock when painted. The bad news...if i had spent some additional dough on better heads, I'd likely have a 10 second car instead of an 11.60 job. Since i have no roll bar, it's not a big deal. Ultimately, the Stealths are a good intro head. If you're looking to go all out racing, there are likely better alternatives.

I too am interested in a direct comparison of the CNC's vs unported. Good luck.

What cam in the 440 and in the stroker Tommy?

find some info on stealth lower lift flow numbers. from what i've seen that's the problem.

Maybe the valve job?

From my bench last Friday.... New head, ootb, stealth valves
and valve job. 4.375 bore, 28" test pressure;

Lift........ In/ex
.100----65/50
.200---144/104
.300---207/139
.400---235/168
.500---247/183
.600---250/192
.700---253/197

I've had a few sets of these come through the shop over the
past few years, and on my bench, mid-250's on the intake is
pretty typical for them in ootb form.

Rule of thumb is 2 hp per 1 cfm increase. So if the ported heads flow 50 cfm more than the unported heads you would be able to see up to 100 hp gain. I've run this test a few times and the rule of thumb is accurate as long as everything else on the engine can support the power increase.

are the new edelbrock rpm's much better?

Same head, same port as above, but with seats recut, mild
back cut on valves, and the bowls and short turns blended.
No rework on the pinch area or around the guide boss.

Lift------in/ex
.100----70/56
.200---146/105
.300---207/142
.400---244/168
.500---267/186
.600---271/201
.700---272/214

Ootb RPM head, ede valve job & valves
Lift-----in/ex
.100----67/50
.200---141/106
.300---209/144
.400---245/170
.500---269/186
.600---275/196
.700---278/201

Just keep in mind, not all ports on all heads flow the same.
These numbers are what these particular ports flowed on
these particular heads.

good to see you posting, don't be a stranger

For comparison, here are some numbers for an Ede E-Street
75cc head. The 75cc chamber definitely has more valve shrouding
compared to the 84cc heads, and has a noticeable impact on
the low and mid-lift flow numbers.

Ootb head with ede valve job

Lift-----in/ex
.100----62/52
.200---122/100
.300---183/137
.400---230/167
.500---262/185
.600---275/195
.700---282/201

From the same flow bench, here are some numbers from some
MCH CNC ported stealths. Stealth valves with back cut, MCH
valve job, full CNC ported, std port size. Average flow for one
left and one right cylinder.(#1 & #7)

Lift------in/ex
.100----70/60
.200---161/113
.300---222/143
.400---263/169
.500---289/189
.600---305/205
.700---309/215

We just ran a 438 inch low deck motor with 75 cc Edelbrock RPM heads and it looked to me like the heads wouldn't flow as much as the "classic" RPM heads. The power numbers were down a bit too. The flow numbers on the Edelbrock website are identical, but it didn't look to me like the 75cc casting would flow as well. Your post is the first set of numbers I've seen though.

i have run both stock Source heads , home clean up , and now CNC Source heads .
On a 440 ci RB +0.055 bore . Solid flat tappet cam 258@050 - 540 gross lift (0.020 lash) , 10.75ish:1 comp
Best ever pass on old heads was a 10.994@120.66 . Only ever ran 1 10 second pass mostly ran 10.10/18 range
With the CNC best pass is in my signature - 10.88's . In fact at a street meet last night with no track prep I ran a 10.893 with a PB on the sixty of 1.497.
Currently has a Eddy Victor manifold , gasket matched only , with Prosystems HP1000 carb .Mostly ran a M1 single plane and sometimes a BG 825 on older Source heads - BUT I had also run the Victor and HP1000 for minimal gains . On the chassis dyno there was about 30RWHP gain . This was all in flow - as the gain was in the swap from the 825 to the HP1000 . Timing needs did not change and only needed I think 1 more jet size in the rear .
I know I need more cam but I am not legal for sub 11's and I do have a another block that is calling out for a 4.25 crank kit
I am very happy with the result . are they a race head NO are they a good performance head YES with the proper prep . The straight plug is really nice too .

Tex

Here's some numbers from a random port on the standard stealth that Brian from IMM flowed for me. This is a home port work that I did.

What he said!

Matt, Both engines ran the Comp Cams .557" lift street roller (23-742-9) is the part number. I love seeing the real world numbers for flow on these heads. They confirm what I thought was the case. Does anyone have flow numbers for 906/452 heads, ported with large valves? It would be nice as a comparison.

i have a set of iron stage 5's that fast68plymouth tuned up.

lift-----in/ex
.1------72.5/57.2
.2-----148.2/117.1
.3-----212.2/168.2
.4-----256.3/200.0
.5-----278.7/202.5
.6-----290.2/204.9

Great seeing you posting Dwayne.

What did you think, they're not flowing much better than stock heads with 2.14/1.81s? The port is significantly bigger though.

TBH I've been trying to figure out why my Stealth headed engine doesn't rock like it should. I had a head off a couple of weeks ago and was tempted to bring it to my machinist to flow it. I went through them, lapped the valves (looked good), and changed the springs, but the ports and valve job are just OOTB.

Its not hard to get a set of 906s to flow what these heads are flowing. I'd think cleaning up a bowls a little, and big valves, and they'd be there. Mr Porter knows for sure how much is required to get them there.

Its certainly very possible your ported iron heads flowed better. I think 906s can safely flow around 280 and not risk cracking from being too thin. Some people get over 300 out of them.

While I have 440source heads and really like them, it still irks me that they over-inflate the flow numbers on their website.

"Intakes flow about 280-290 CFM as cast, with the potential to reach at least 330 CFM or more with porting."

While I see many people posting how "normal" home port jobs on
OE iron heads can easily flow 260-270-280+, the fact is, those
cases are few and far between. The typical big valve 906/915 type
BB head that was home ported or not done by a shop that is well versed in
preparing racing heads usually flows in the 240's, or less. It's takes
a fairly skilled person with a good understanding of those heads to
get them to flow in the 270's +.
This is one of the main reasons heads like the RPM's and Stealths
so often outperform ported OE heads without any additional work
done to them. The home ported "260+ cfm" heads aren't usually as good
as the owners think they are. Unless they have been on a flow bench,
you'd really just be guessing.

Here are some numbers from some recent heads that came through
my shop for freshening/updating. Neither of these sets of heads were
home ported, but done by a regular machine shop that wasn't necessarily
specializing in head port work. They had the usual big valve install
and some amount of associated blending along with some blending
of the pushrod pinch area.

915 head, older MP 2.14 intake valve with back cut/ new Ferrea
1.81 exhaust valve with back cut, and I freshened the valve job.

Lift------in/ex
.100----70/48
.200---145/99
.300---196/133
.400---227/161
.500---236/181
.600---234/191

906 head, SI stainless 2.14/1.81, no back cut, used valve job
(But not many miles on it) with radius as bottom angle on
both intake and exhaust.

Lift------in/ex
.100----69/48
.200---124/94
.300---180/129
.400---227/158
.500---241/178
.600---245/193

So, it's pretty easy to see how even an OOTB Stealth head
should be able to provide a nice improvement in performance
over these two sets of reworked OE heads, and these are
really fairly typical of what I see.
I will add this, for the average home porter, the 346/902/452 heads
are much easier to get to flow 250+ cfm, and are also a better bang
for your porting $$$ if you're paying to have the heads reworked.

I figured I'd throw in these numbers too....
452 heads with 2.14/1.81 valves, done by a well known mopar
volume head rebuilder, no porting, no blending. To the best
of my recollection, these are the worst flowing big valve heads
I've come across. They had a big "bowl hog" type cut done under
the valve job that really hurt the flow. IIRC, these flowed less than a
completely stock head with the OE valves and valve job.

Lift------in/ex
.100----67/52
.200---118/97
.300---169/129
.400---196/141
.500---217/145
.600---222/145

Andy, were those the 75cc "RPM" heads or the "E STREET" heads?
If they were the RPM heads, were the chambers machined or as cast?

Sorry, .575" lift roller, not the .557 i had written above.

As a point of reference, these are the intake flow numbers for a
906 "F" head dated 10 11 8. While not all F heads are great, the
best flowing untouched 906's I have tested have been F heads.
This particular head had a very well preserved OE valve job and
Is tested here with an OE valve and no back cut.

Intake test only-
Lift------In
.100----62
.200---122
.300---179
.400---214
.500---224
.600---235

On a head like this, once you start to blend the bowl and increase
the potential for more air to flow through the port, the short turn will
become a limitation and the port will go turbulent, usually between
.400-.500 lift, and the flow will drop off unless you start reshaping
It.

[quote=fast68plymouth]While I see many people posting how "normal" home port jobs on
OE iron heads can easily flow 260-270-280+, the fact is, those
cases are few and far between. The typical big valve 906/915 type
BB head that was home ported or not done by a shop that is well versed in
preparing racing heads usually flows in the 240's, or less. It's takes
a fairly skilled person with a good understanding of those heads to
get them to flow in the 270's +.
This is one of the main reasons heads like the RPM's and Stealths
so often outperform ported OE heads without any additional work
done to them. The home ported "260+ cfm" heads aren't usually as good
as the owners think they are. Unless they have been on a flow bench,
you'd really just be guessing.

Here are some numbers from some recent heads that came through
my shop for freshening/updating. Neither of these sets of heads were
home ported, but done by a regular machine shop that wasn't necessarily
specializing in head port work. They had the usual big valve install
and some amount of associated blending along with some blending
of the pushrod pinch area.

Very true. The areas of the 906 casting that need work to get the CFM in the 260 + range are kinda hard to get to. Then when you start getting real good number you cut through the short side. The numbers you are posting reflect the numbers that I get on my bench. So far the best 906 that I have tested was 300 CFM. The short side was flat as a board. No idea how they got that lucky.

So how does that guy from out west get 340+ cfm out of 906's?

A few years ago there was a magazine article where someone was
offering CNC ported 906 heads. I believe it was Muscle Motors.
As I recall they were reported to flow something 312cfm on the intake
side. I've had a set of those in the shop, just as delivered from MM
with 11/32" stem valves, 2.19 intake and 1.81 exhaust.

Lift------in/ex
.100----68/61
.200---145/109
.300---241/145
.400---256/171
.500---284/191
.600---290/204
.700---288/204
.800---290/205

On my bench, while not 312cfm, that's still a very good 906 head,
and as big as they looked, it was only like 217cc's as I recall.

I have an old article that explains that some of the well known Mopar ported head that you see for sale are advertised with flow numbers at 32 - 34. Not the 28 that most people are used to. I have had some on the bench and they flow around 275 280 at 28. Crank it up to 32 and they flow around 320.

Wonder how long it takes those 300 cfm 906 heads to crack and hydraulic cylinders?

Back to some Stealth numbers...
I had a set of Stealths come through the shop that had a season
of drag racing use on them. I re-cut the seats, back cut the valves,
and blended the exhaust bowls. On the intake side I opened the
pushrod pinch to 1.125", blended the bowl and also opened up
the bowl area in the roof adjacent to the guide boss, as well as
removing most of the guide boss itself.

Lift-----in/ex
.100---70/56
.200---143/112
.300---205/145
.400---249/170
.500---279/188
.600---286/201
.700---289/210

The straight wall in the intake ports on these heads are fairly
"lumpy". I think if you started out with the level of work the same
as the test above, then straightened out the lumps on the straight
wall, and took a little off the other three walls, and then smoothed
everything up, you'd end up with a port that flowed somewhere
around 295-300 cfm.

Fast68, you are the Man! Thanks for injecting some reality.

R.

Can't argue with real world numbers, very insightful!

Very happy flow bench. Ron

dwayne it is good to see you posting again, i had stock stealth's and changed to some of porters indy -1's that were heavily reworked. i couldent be happier with the results, the stealths went on the wifes challenger and when money allows i will send them to porter as well.

Wow, I've been missing out on all the fun..........

2" tube on the exhaust.......28"..........

Lift.............Stock 906..........906 Ported

.100................66/54................89/60
.200.............131/103............161/129
.300.............189/145............212/185
.400.............222/168............257/216
.500.............234/176............297/234
.600.............237/183............331/253
.700......................................347/264

These 906 heads were on our 500" engine when Comp Cams forgot to turn the water on to the engine. It got so hot that the paint was burning off the cylinder heads and all the exhaust valves seized to and pulled the bronze guides out of the heads. The valves were then pounded out of the guides, the guides knurled on the outside and pounded back into the heads, reamed and the valves stuffed back in. With 15 bent valves and 11-56% leakdown it then made 730 HP on 93 octane pump gas. Oh yeah, the heads never cracked and still don't leak water.

Lift......Best OOTB Stealth ever tested.......Fully ported

.100...............73...........................73
.200..............151..........................152
.300..............214..........................218
.400..............245..........................267
.500..............262..........................308
.600..............276..........................337
.700..............281..........................346

With the 2" pipe the Stealth exhaust ports will approach 300 cfm when ported.

Jim L - Are you still using a SF-110 (like myself) and having to throw big correction factors into the results (again, like myself), or have you upgraded flow benches since the last time I asked about your equipment?

When I see BIG starting numbers like this it raises LOTS of questions about flow bench calibrations.

.100...............73...........................73
.200..............151..........................152
.300..............214..........................218
.400..............245..........................267
.500..............262..........................308
.600..............276..........................337
.700..............281..........................346


I have had a lot of Stealth heads on my bench and when I test I test EVERY port on every head. The most I have ever seen was 267cfm. Start with high numbers end with high numbers and those in the know, know better.

I spoke with my customer the day other on this set of Stealths I have in the shop. From our original conversation I had assumed he was only looking for the "bowl blend" level of porting done to these heads. After our conversation the other day he indicated he was more interested in having them flow solidly in the 280's+, so I went in and opened the pinch to 1.140 and trimmed the guide boss and the port roof adjacent to the boss. This is the same port as the other two tests from earlier(#1).

Lift------intake flow
.100----71
.200---146
.300---211
.400---254
.500---277
.600---285
.700---290

Here are some intake port volumes to give an idea of how much work is involved to get from one level to the next. I didn't check the OOTB port volume, but the bowl blend only removes a couple of CC's worth of material.

Recut seats, blend bowls = 210cc
Open pinch to 1.140, narrow guide boss = 217cc
MCH full CNC ported and valve job = 252cc

On an Edelbrock head, if you do a basic port and polish it'll flow right at about 300cfm, and those ports are usually in the 228-230cc range.

Same oh, same oh. Too bad I'm not wealthy. Just staying alive.

This! ^^^

I look at it this way: I see 9 out of 10 very good head porters have results within 10 cfm of each other. Then I see one guy with results that are nearly double that of the other guys. Who is the outlier? Or, am I to believe that Dwayne and the other head guys here are a bunch of know-nothing hacks?

I had Jeff's/MCH Eddy's checked on a local bench and the numbers were within 1 cfm of each other. Trust, but always verify.

Not all flow benches are the exact same on results, same on the operators sometimes also
Changeing the subject for clarification, is the 2 HP per CFM directly related the the head flow results or does it apply directly to the C.I. of the motor the heads are on In other words if the heads flow 200 CFM will they only make 400 HP regardless of the C.I. or does it mean that those heads on a 300 C.I. motor will make 600 HP

Thanks for the softball question.....

Ground Rules: This is a rule of thumb question and will get a rule of thumb answer.

The number is actually a little bit more than 2 hp / cubic inch, but it applies to head flow. The size of the engine determines what rpm this peak power will need. So let's pretend the number is 2.000.

With a 200cfm head on a 400 cubic inch v8, suppose peak power was at 400hp at 4000 rpm. Put that same set of heads on a 300 cubic inch v8 and peak power becomes 400hp at 5333rpm.

Back in the day, I spent Christmas vacation in the ME Library at my University. They had a complete set of Journals of the SAE. What a treasure chest. I read papers by men like Fred Duesenberg with power curves of the same engine with a two valve head and with his four valve head. I read papers on the development of the Dynaflow, which was basically the beginning of torque converters. And from the '50s I read papers from the pioneers of the hot rod industry. The paper that changed my thinking was on flathead Fords. The author had built an engine in three different displacements and posted dyno curves for each configuration. The max power for each size engine was exactly the same. The curves were just arranged from largest engine to smallest engine, along the rpm scale. Displacement only shifted the power curve right or left, it didn't change the amount.

R.

some people use clay for the port entry test, some use nothing,some use a machined radius made for a particular cyl head, the flow #'s can be all over the place. I started using a radius to get more consistent results.

I see numbers like this and just about unbelievable hp numbers thrown around on a different site that I find hard to believe at all. If I believed some of the numbers thrown around at that site then I would be saying that porter works true magic on every head they touch. And I mean magic thats just not possible. Ron

LaRoy Engines, You guys are able to pull some incredible 906 head flow numbers, and dyno horsepower results!!! What head flow numbers and dyno results are you able to get with ported 440 Edelbrock RPM heads on a 440 and larger cubic inch like 470 or 505 ?

Interesting articles about LaRoy Engines I found with a few minutes of google searching. I've been impressed with them during the Mopar Muscle Engine Challenges they have entered and done well.

http://www.hotrod.com/events/coverage/mo...ax-performance/

http://www.hotrod.com/events/coverage/mopp-1203-the-amsoil-mopar-muscle-engine-challenge/

http://www.bigblockdart.com/forum/showthread.php?21093-La-Roy-Engine-in-Mopar-Muscle-WOW-AGAIN

https://board.moparts.org/ubbthreads/ubbt...heads-from.html "I'd recommend Jim and Cody LaRoy of LaRoy Engines in Challis, ID. They do hand porting only and put the Edelbrock RPM heads into the 345 cfm range at .700" lift and the Victor heads 365 cfm at .700" lift. (208) 879-2969."

http://www.forabodiesonly.com/mopar/showthread.php?t=172734

I've had a ported set of 906 heads, and a ported set of 915 heads. Lost both after 5 or 6 years of bracket racing and occasional nitrous use. While I believe it's possible to get good numbers out of them...it just doesn't make sense to me to spend all that time or money on 40 year old castings that are prone to crack.
Bought a set of Edelbrock RPM's, broke two engines under them in 8 years of hard running, then cleaned them up and sold them to my brother for 75% of new price, and he's got three years on them.

Bought a set of Stealth CNC heads, and bolted them straight on my street 440, love them so far, and like the Eddies, I bet I can recoup 60 to 75% of my investment if I decide to re-sell at some point.

Bottom line, if I'm going to spend 1000-1500 on CNC or hand porting, it only make sense to spend that on a solid, reputable, and repairable casting.

I usually want to see track results rather than bench racing. PRC's stuff does what it does, and it proves the numbers he gives. I've seen this first hand having closely looked over his work - and not just his heads. The huge numbers I see elsewhere are always bench and dyno numbers and are never backed up on another peice of equipment. Nothing associated with a car racing in some form where actual output could be quantified without ambiguities. I'm all for teting and bench racing, but unless it's accelerating a mass downa track, it's just conjecture.

I would love to get a peek at the 906 heads used for the flow numbers above. They are awesome!

I'd like to see them in a car, to see how they stack up at the track.

Bowl hog? Is that like running a 70° stone as far as you can take it? If not porting, how should it be done when installing bigger valves?

The throat size is a percentage of the valve size. Go to big and you might as well scrap the heads or use them for door stops.

"If not porting, how should it be done when installing bigger valves?"

IMO, if you're planning on installing larger valves in an effort to increase the airflow capabilities of the heads, then some amount of porting should be considered as a mandatory part of the big valve upgrade.
In fact, if I had to chose between mild bowl porting or bigger valves, I'd take the bowl porting, especially if the heads in question are 346/902/452 heads.

Inches of vacuum when tested?

"Inches of vacuum when tested?"

As stated in my first post, tested at 28" pressure on a 4.375 bore.

To revisit the volume rebuilder 452's....
As rec'd-

Lift------in/ex
.100----67/52
.200---118/97
.300---169/129
.400---196/141
.500---217/145
.600---222/145

Recut seats, back cut valves, blend bowls, open pinch to 1.040-

Lift------in/ex
.100----68/60
.200---139/109
.300---201/146
.400---244/171
.500---259/182
.600---255/188
.700---255/190

With the 2.14/1.81 valves installed, the later (346 and newer) heads really respond well to a little blending work.