Engine and Transmission Tech

> Anyway 140cfm looks to be very conservative given the dyno figures

140 CFM is meaningless unless accompanied by the pressure drop
the flow rate was taken at. Flow at a 10" or 15" drop reads
much lower than flow at a 25" or 28". Pictures of the Merlin
exhaust ports and chambers look very much like the pictures I
have of David Vizard's welded and ported Rover heads (see
attached photos).

Several weeks back, I was contacted by a guy who has tested
the Merlin heads against a set of home ported 4.6L Rover heads.
His maximum power at the flyweel is 274 hp @ 5565 RPM with the
4.6L Rover heads and 285 hp @ 5547 RPM with the Merlin heads.
Not much of an improvement but that's likely due to intake and
carb, as well as the camshaft. He was running an Edelbrock 500
CFM AFB carb on an Edelbrock Performer Rover dual plane intake
with a 1 inch spacer and K&N filter and stub stack. The cam
was Real Steel's Typhoon hydraulic grind which is 218/218 degrees
duration @.050" and .480"/.480" lift. The Merlin heads have a
slightly larger combustion chamber which dropped the compression
from 10.4:1 to 9.8:1. He's ordered a single plane intake from
Willpower and has Real Steel's Tornado cam to try, along with a
600 CFM AFB carb.

Does anyone know what headers, intake manifold and carb were
used on the Merlin test engine on the Real Steel website?

Dan Jones

I just went back and looked at an old article (Headline News - Flow Tests
Blow by Blow) in the February 1996 issue of CCC Magazine that presented
the results of flow bench testing a set of Wildcat Engineering Rover heads.
The Wildcat heads were still under development at the time and were fitted
with 1.88" intake valves and made peak flow of 127.54 CFM. No pressure
drop was quoted but it was noted that value represented a gain of over a
ported Rover race head of 24%. They must be testing at a lower pressure drop.

Dan Jones

Dan -

Do you know the size of the valves in the Vizard heads? They appear to be much larger than the 1.7/1.5 "largest" I've seen for the Rover. The seat inserts must be very thin (OD minus ID) and they look to be butted right up against each other.

Dan and all, I think Wildcat flow rates at 10", might explain the alleged 140cfm. with Merlin's. On Davids' head,moved "outboard" approx. .25" toward center of bore? I have (4) raw cast Stg II Buisk V6 heads I planned to Electron Beam weld together. I home ported one cyl. with Ferrea 2.02 Int. and 1.55 exh.both w. 7mm stems pulling thru a 3.75 bore @ 28" netted 294cfm/.600 lift. The "ancient Stg II" head is superior in design and flow compared to anything being produce"anywhere" for the Rover. All of the current designs seem afraid to change to a race inspired design. It seems to me, anyone spending the $ for Wildcat's or such would also want the best including intake, exhaust and billet cam? Maybe I'll just lumbar-on with waay ancient "907" heads.roverman.

Wildcats website says they test at 10"..
[www.roverv8engine.co.uk]

Even a stock Rover head flows 140 @28"

[users.erols.com]

My question on Merlin heads would be this. Are they actually any improvement over a well ported 64 Buick 300 head?

Greg

> Do you know the size of the valves in the Vizard heads?
> They appear to be much larger than the 1.7/1.5 "largest"
> I've seen for the Rover.

I do not.

> The seat inserts must be very thin (OD minus ID) and they
> look to be butted right up against each other.

I'm running 1.775"/1.5" in my Buick 300 heads in the stock
location and they are quite close to each. I suspect Vizard
has moved the guides a bit.

> Dan and all, I think Wildcat flow rates at 10", might explain the
> alleged 140cfm. with Merlin's.

140 CFM @ 10" equates (roughly) to 234 CFM @ 28".
Eyeballing the port, that seems optimistic. Flow
at 10" converted mathematically to 28" usually does
actually flow as well as the converted numbers
suggest, though.

> The "ancient Stg II" head is superior in design and flow compared
> to anything being produce"anywhere" for the Rover. All of the
> current designs seem afraid to change to a race inspired design.

If I were doing a new head for the Rover, it would be a canted
valve design but not hemi. Hemispherical chambers have poor
octane tolerance. Instead I go with a canted valve with a
generous quench pad like a closed chamber 351C or my favorite
Ford Motorsport C302B heads. Canted valves permit larger valves
in a given bore size and unshroud as the valve opens and the
quench chambers tolerate more compression on a given octane
rating. Specifically, I'd scale a Ford Racing D3 head. With
relatively small port areas, they flow 434 CFM at 28" with the
best low lift flow Vizard has ever measured.

> Wildcats website says they test at 10"..
> [www.roverv8engine.co.uk]

Okay.

> Even a stock Rover head flows 140 @28"
> [users.erols.com]

I don't see any Rover V8 head data on that site
though I do see 1.8L Rover data. The Buick 215
and Buick 300 (ported and unported) appear to be
heads that I flowed. The Olds 215 appear to be
numbers I posted from the British V8 newsletter.
The Ford C302 heads that he claims were ported
by Stiegemeyer Racing were heads I had flowed at
Stiegemeyer but Stiegemeyer did not port them.
I only used his bench. I see some typos in that
data, though.

> My question on Merlin heads would be this. Are they actually any
> improvement over a well ported 64 Buick 300 head?

Good question.

Dan Jones

Dan, Thanks for your skilled reply, as always. Initially, I like the "late" design of the Mopar 5.7/6.1 semi-Hemi chamber. Fast burn/turbulence, quench and relatively shallow chamber. All it needs is a "real" Hemi rocker cover with plugs in the middle. Regarding the "Merlin" head, they seem pretty- Smokey Yunic about it? I haven't seen any data of port velocities, flow, intake manifold or all the cam spec's on their "sales" motor. I don't remember seeing flow's on the stock, alum. 300 head, but can't be too impressive with 1.625 and 1.315 valves. Changing seats, valves and porting are all expensive."Merlin" may be a good investment for a street motor but would be nice to get the facts. roverman.

Dan, I called Real Steel a few weeks and got some replies. Their 5 litre stroker was run with a Australian single plane manfiold and 465 Holley if I remember correctly. Apparently they do not give much credit to Performer carbs. Don´t remember the exhaust sizes but since I have ones with 1,5" primaries Charlie at Real Steel felt that they might restrict the output. In case somebody wonders I am the person Dan wrote about. I did receive the Wilpower manifold, cleaned it up some and have fitted it. Unfortunately we have snow at the moment so a trip to rolling road is not possible with summer tires. Weather forecast predicts rain for the weekend and the roads should be clear by next Monday so maybe next week it might happen. I am curious to see if the manifold helps the situation. I don´t think that the 500 cfm should restrict that much. I might do something to up the CR to about 10,5:1 and may even take the heads to a shop for flow measurements.



Edited 1 time(s). Last edit at 11/13/2009 07:25AM by minorv8.

> Dan, Thanks for your skilled reply, as always.

You're welcome.

> Initially, I like the "late" design of the Mopar 5.7/6.1 semi-Hemi chamber.
> Fast burn/turbulence, quench and relatively shallow chamber.

Agreed.

> I haven't seen any data of port velocities, flow, intake manifold or all
> the cam spec's on their "sales" motor.

Here's what's posted on their website:

On Friday May 4th 2007, we dyno tested the final version of our "Merlin F85"
heads. The heads were fitted to a 5 litre engine, which had been converted
from a 3.9, using our 5 litre stroker kit. The heads performed very well,
and you can see by the graph on page 4, that we obtained 353ft lbs of torque.
Also, the torque exceeds 321 ft-lbs between 2500 & 5500 RPM. These figures
were obtained using 10.5:1 compression, and our new "Tornado camshaft,
224/231 degrees @ .050 lift, .508"/.512" lift. The cylinder heads are much
stiffer than the standard Rover unit, which can distort easily, and the
rocker gear is not very stable. Two extra rocker pedestals are supplied for
each head. Rocker covers are supplied, complete with bolts. Valve guides
are manganese bronze, and the valves are stainless (1.73 & 1.45 ). The
exhaust seats are very hard, and will withstand most fuels including LPG.
As supplied, the heads are good for .500" lift. Use an BYRC9YC spark plug
to begin with. Exhaust ports are raised slightly. Regular inlet manifolds
fit. Special head bolts required.

They didn't list the lobe separation angle. Do you know Jukka?

> I don't remember seeing flow's on the stock, alum. 300 head, but can't be
> too impressive with 1.625 and 1.315 valves.

Valve Buick 300 Exh/Int Buick 300
Lift 1964 ratio 1964
(inch) aluminum (%) aluminum
ported unported
Int Exh Int Exh
1.775" 1.5" 1.625" 1.312"

0.100 66 47 71.2
0.150 99 82 82.8
0.200 129 104 80.6 105 96
0.250 155 119 76.8
0.300 174 130 74.7 135 108
0.350 187 139 74.3
0.400 191 146 76.4 142 115
0.450 194 150 77.3
0.500 196 152 77.6 149 115
0.550 200 153 76.5
0.600 200 153 76.5 154 116

Flow numbers were taken on a Superflow bench at 28" H2O with a clayed intake
radius but no exhaust pipe. Heads were ported by Jon Carls of JDC Engineering
in Minonk, IL. 6000 Series Ferrea Buick V6 Stage 1 valves were used. Intake
valves are part number F6238 (1.775" head diameter, 11/32" stem, 4.735" long
with a 0.271" tip). Exhausts are part number F6237 (1.5" head diameter, 11/32"
stem, 4.735" long with a 0.254" tip). Intake head shape is a 10 degree Super
Flo. Exhaust is a 29 degree tulip. Ferreas 6000 Series valves are competition
parts suitable for solid roller cams. The larger valves required larger seats,
p/n 30903 for the intake and p/n 30647 for the exhaust.

Pictures of the ported heads are shown here:

[www.bacomatic.org]
[www.bacomatic.org]

I thought the valve OD would need to be reduced slightly but it looks like they
just fit. I gave Jon a junk head to experiment on and he said he actually pulled
better numbers on the test head. I can see spots where he intentionally went
through the aluminum into the water jacket. These heads are destined for a
street application, so it was important to leave adequate wall thickness.

I'm happy with the results. The exhaust to intake flow ratio is good
and the low and mid-lift numbers are excellent. Pretty good for such a
small valve head and should support my HP goals.

The unported Buick 300 heads flow about as well as a factory Ford 5.0L
HO Mustang head and the ported heads flow about as well as the entry
level aftermarket small block Ford heads, though there are much higher
flow heads available for the SBF.

Valve Ford 5.0L Ford GT-40 Ford GT40X
Lift HO E7TE
(inch) cast iron cast iron aluminum
unported unported unported
Int Exh Int Exh Int Exh
1.78" 1.45" 1.84" 1.54" 1.94" 1.54"

0.100 54 47 54.6 53.1
0.200 92 78 107 94 107.8 110.2
0.300 130 95 157 119 159.5 144.7
0.400 141 102 183 128 197.2 150.3
0.500 155 106 192 128 217.4 150.4
0.600 158 105 196 129 227.8 149.4
Super Ford MM&FF
Sept. 1991 Jan. 1998

> Changing seats, valves and porting are all expensive."Merlin" may be a
> good investment for a street motor but would be nice to get the facts.

Yes. While the Buick 300 chamber size works well on my 4.8L engine,
it would be nice to have an option with a smaller chamber that can be
used on smaller displacement and stock piston short blocks.

> Dan, I called Real Steel a few weeks and got some replies. Their 5 litre
> stroker was run with a Australian single plane manifold and 465 Holley if I
> remember correctly. Apparently they do not give much credit to Performer
> carbs.

Carb preference can be like religion to some. In my experience, the
Carter AFB and AVS carbs (same as Edelbrock Performer carb) make fine
street carbs and can be easily tuned for fuel economy and power. On
higher performance engines, Holley 4150 type carbs will generally make
better power, given equal flow ratings. Also, Holley's modular design
makes it easier to modify for more radical engines. 465 CFM is still
on the small side for a 5L engine. The Ford 5.0L HO used a Holley 4180
of 595 CFM from the factory (before switching to fuel injection) and on
modifed 5.0L engines of 300 to 350 HP, it is common to use a 700 CFM
Holley DP (Shelby used a 715 CFM Holley on the 306 HP 289 HiPo V8's).

> Don't remember the exhaust sizes but since I have ones with 1.5" primaries
> Charlie at Real Steel felt that they might restrict the output.

1 5/8" primaries should help. Are these 4-into-1 or tri-y design?
In my dyno testing, the mufflers have been the biggest restrictions.
I've seen losses of 50 HP with mufflers. The best mufflers lose
virtually nothing to open headers.

> I am curious to see if the manifold helps the situation. I don't think
> that the 500 cfm should restrict that much.

500 CFM carb on a dual plane is more restrictive than 500 CFM on a single
plane open plenum intake. That said, Vizard's testing has shown that some
open plenum intakes are very sensitive to being under-carb'd. However,
that was on a 350 SBC with race heads, so the results may not carry over
to our little port engines.

watch vacuum levels on the dyno pull, if it starts going up...

> I might do something to up the CR to about 10.5:1

Milling the heads to get 10.5:1 will make a worthwhile difference.
Compression raises the torque curve at all RPM levels, so the area
under the curve is much greater than the peak difference might suggest.

> and may even take the heads to a shop for flow measurements.

Please!

Dan Jones

> They didn't list the lobe separation angle. Do you know Jukka?

It´s a Comp Cams grind and the LSA is 110 degrees.

>1 5/8" primaries should help. Are these 4-into-1 or tri-y design?
In my dyno testing, the mufflers have been the biggest restrictions.
I've seen losses of 50 HP with mufflers. The best mufflers lose
virtually nothing to open headers.

They are 4-1 with unequal length primaries. Design based on available space. Rest of the system is 2" dual with single jaguar X-type mufflers in the back.

Those Vizard heads are works of art. I see that the chamber was welded into a heart shape. I'm a little curious about the 8 shaped head bolt holes. Was the head angle-milled?

The heads were moved on the deck to get the valves closer to the cylinder centreline.

Update: took the car to rollers today after the manifold swap. The result was 20 hp increase to 305 hp and a loss of torque low down. Single plane was better than Performer from 4700 rpm upwards. The big surprise is that practice and theory met big time. That´s what it was supposed to do. So, suffice to say that Performer manifold is close to its limits at around 280 hp. Now, there are interesting options for the coming winter...

Jukka, So by "rollers", 305hp. measured at rear wheels? Perhaps you could post a print-out? If that single plane is open plenum, you may consider a "drop-in" divider similar to what "Huffaker" used for street use on their race manifold.Carb spacer? It woud take some experimentation to optimize for for your build, but this plate is tunable.roverman.

Roverman, sadly the hp figure is corrected at flywheel. And yes the intake is open plenum and the 1 inch thick spacer is 4-hole version to suit Edelbrock carb. I haven´t seen any pics of the Huffaker divider, I tried to search the net for manifold tuning tricks but there were very few pics to be found.

Jukka.. ca you give details about the engine at the time of the last dyno..

Bore , stroke , compression.. etc, etc?

Jukka, You may want to consider, "stepped primaries" on hedders, say 15/8"x12" up to 13/4", depending where you want the power at, or anti reversionary cones at exhaust ports. Either should produce a stronger "signal" to carb and possibly enhanced torque curve. Goot Luch, roverman.

As we can see, the out-of-box Merlin head, lags behind the large valved/fully ported, 300 head. We'll se what the "worked" version does. roverman.

My '64 Buick 300s fitted to my 4.6 SD1 (ported by The Head Stud Development Co, Melbourne, Australia)

1.75in / 28" = 191cfm@550 thou lift
114cfm @10"
1.5ex= 147cfm@550lift