Bingo, that is the point. The stock 4.6 is good for a ver reliable and
long lived 450 horsepower on all stock internals, with no ill effects. That
is 150 horsepower (+50%) increase, without changing anything in the bottom
end or the heads.
Ford sees a 50% horsepower increase on their OHC modular engines with a
simple bolt on blower, on SOCK internals, while the Corvette and Viper push
rod offerings are maxed out and need all new internals to up their
horsepower numbers from the maxed out factory figures...
Come on now clare, this is not rocket science...
Go ahead and get your apples out and tell us just how this reflects well on
the Viper or the Vet's "technology" advantages?
The SRT10 viper and the normally aspirated 'stang both had 9.6:1 CR
stock. In 2007 the standart viper had 9.2:1. In 2008 the SRT10 goes to
The 2008 SRT10 8.4 liter Viper puts out 600 HP normally aspirated for
74.5 HP per liter at 6250 RPM. It puts out 560 ft lb of torque, or
almost 67 ft lbs per liter.
If you boosted this engine to 7psi ((same as Stang) you would see
almost 100 HP per liter, and torque in the 90 ft lb per liter range,
with CR down around 8.5:1
The GT500 supercharged 5.7engine has 8.4:1 native compression ratio .
It makes 500 hp at 6000 RPM. That's almost 88 HP per liter. It puts
out 480 ft lbs on 150% of atmospheric pressure at the intake.
That/s just over 84 ft lbs per liter.
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Can the Viper engine take 7 psi of boost with no internal engine
modifications? The Mustang's 4.6L can take 9 psi with no modifications.
The GT500's engine isn't even breaking a sweat at 500 hp. Ford slapped
an inefficient Roots blower on it and detuned it. A Kenne Bell twin
screw kit on a GT500 will make nearly 700 rwhp on pump gas. That
equates to 150 hp/liter and you can fill up the tank at Sunoco. This is
also done without removing the valve covers or oil pan from the engine.
I wasn't talking about the N/A Cobra engines. My comparisons are
between today's Viper and Mustang engines. Ford builds more headroom
into their modular V-8s. Can a Viper engine handle a 50-60% increase in
power output without removing the valve covers or oil pan? I know the
Mustang's OHC engine can.
I'm not even talking about the blown 4.6L from the factory. The Mustang
GT engine can take 9 psi with little risk if the tune is right. Where
the Viper and Z06 engines are pushed closer to their limits from the
factory the 4.6L engine in the Mustang is not and it still makes
hp/liter numbers on par with the other two engines. If Ford pushed the
4.6L as far as the Viper and Z06 they would pass those motors in
hp/liter output, IMO. I know the after market tuners are getting 30-40
more rwhp from them with tuning alone while maintaining reliability and
meeting emissions requirements. Imagine what Ford could do with tuning
the 4.6L in the Mustang if they had the motivation.
The whole point of the discussion here is that, IMO, OHC engines have
inherent design advantages over OHV engines. The fact that Ford's OHC
4.6L in the Mustang is matching the Viper and Z06 hp/liter numbers and
still has enough headroom to handle 9 psi of boost shows the superiority
of the OHC design, IMO. Ford could easily place four valve heads with
VVT and raise the redline to 7,500 rpm (the OHC design makes high
redlines easier to achieve) and get 400+ hp from their 4.6L engine.
This would be more hp than the LS2 using 1.4 liters less engine
You can also read this as Chevy and Dodge engineering their motors to be
ready to roll right off the showroom floor, whereas Ford is leaving it
up to the customer to spend aftermarket dollars to bring the engine up
I know you've already claimed that Ford doesn't have to, but have we
heard of _any_ development to do so, especially in light of what's
coming down the line? We've heard that the new Corvette motor is a
given, but what's up with the Boss/Hurricane? Rumors abound...
That's the problem. We have to imagine.
I might say that the whole point is to discuss the
advantages/disadvantages. I don't think it's a given that OHC motors
have it over OHVs.
Sorry, Michael, but I can't buy it. I see it as the 4.6 being "under-
You can say similar things for every maker. Every engine being made
today could benefit from more research, engineering, and testing.
However, doing so would perpetuate the discussion forever, as it's all
conjecture. Let's talk about what you can buy right out of the showroom
and drive home. ;)
I read something about the Bullet engine the other day but it was mostly
guessing. I would imagine that any Mustang variant between the GT500
and GT with have to be N/A or it will cut into GT500 sales. My guess is
the Bullet will be a beter tuned GT engine that cranks out around 340
hp. I think Ford looks at the Boss label as a premium one and will do
something special for the engine like giving it a high redline, four
valves and/or raising the displacement to five liters. I think it will
also be priced accordingly (aka too high). Then again, I could be full
of shit too.
Ford has no competition against the Mustang so they really don't have to
do squat. Funny thing is that without competition they are offering us
a very good car. IMO, they are giving us the best lineup of Mustangs
ever. I include the 1960s Mustangs in that statement.
I don't think OHC engines are an order of magnitude better. IMO, they
allow more tools at the engineer's disposal to make power reliably and
with less manufacturing cost. The OHC engines offer multi-valve heads,
VVT, multiple intake runners and very high rpm capability to name a few.
They can be designed to match an OHV engine and then some. Just look
at the newer OHV engines, they are taking design elements (like VVT)
that have existed in OHC engines for almost a decade or more.
The other thing that I think is going to ultimately make OHV engines hit
a wall is displacement. From what I see in the Vette and Viper they
have to have cubic inches to get the power levels those cars need. How
far can they go with this design philosophy? Even in the hay days of
the 1960s there were displacement limits. The Z06 is at 427 cubic
inches already with and engine that is stroked to the moon and back.
Basically, an engine is an air pump. The more air you move the more
power you make. The OHC design allows more flexibility to move the air
more efficiently. Not and order of magnitude more efficiently but a
What you call "under engineered" I call untapped potential for making
more power (i.e. headroom). I think Ford intentionally does this to
give the Mustang buyer the ability to tweak his car to get more
performance for cheap. I think Ford chiseled this in the Mustang's list
of commandments when they conceived it back in the 1960s.
Well then we have to through the engine in the GT500 into the mix. That
starts a whole different discussion between forced induction and N/A.
IMO, that is a short argument because forced induction is the clear
winner in any hp/liter discussion.
Hey, most of us are (some more than others though). At any rate, if
Ford does come out with Bullet/Boss/Hurricane engines, what the hell
will they put them in?? The Mustang can't go much higher in price,
which would be a must for those engines.
Not yet, at least. But that's all part of what we're talking about
Absolutely! I think the Mustang is one of the best deals out there now,
even with "only" 300hp. ;)
Totally agreed. Like Patrick used to say (poorly paraphrased), it's a
great time to have a driver's license. ;)
They'll either go to V10s or big blocks. LOL!
I was sort of being facetious, but at least I was able to make my point.
Great thought, but I don't think Ford goes that far. I think they
figure out how to make money and that's about it.
OK, sounds good to me. :)
For the life of me, I can't figure out why they stopped making the
If you take all the years it's been out collectively, that's a given.
However, if you go a year at a time, my money would probably be on Honda
aftermarket parts. I see a helluva a lot more ricers with aftermarket
stuff than Mustangs.
You can build a 1966 Mustang totally from parts for significantly less
than you can restore a "decent" Cuda , Challenger, Charger, or
virtually any other Mopar of the period. And Chevy falls in between
somewhere. A Camero or Chevelle is easier / cheaper to rebuild than a
Mopar because there are more parts available, at a significantly lower
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Right now I think Ford is in survival mode and I doubt we will see those
engines any time soon. Ford doesn't lack good engines now and, IMO,
doesn't need the added financial burden of delivering them. Besides,
you make a good point, They have nothing to put them in at the moment.
I still doubt the Camaro and Challenger will see the light of day. I
just don't think the bean counters are going to let them happen. Not
enough profit in them to matter in the company wide bottom line. Bean
counters don't care about image cars.
I also give Ford tremendous credit for producing the Cobra from 2003 on
up. Those cars are no-holds-barred ass kickers. They are made in the
true spirit of the muscle/pony cars back at peak of the 1960s. No other
car maker has had the balls to deliver those kind of vehicles in recent
Actually, I think they will go the OHC route first. Did you hear that
Chevy is bringing the ZR1 back? Wanna bet it has an OHC engine? ;)
IMO, the other reason they do this is to allow them to be beat on by
their drivers and still keep running past the warranty period.
My guess is they didn't want to spend the money to R&D, and tool up, for
the new truck chassis. The bean counters probably said the cost wasn't
worth the profits. It looks like they killed the full time AWD,
supercharged Sport Trac too. That looked to be one beast of a vehicle
in the spirit of the old GM Typhoon and Cyclone.
So except for the Mustang (with a few engine variations), are you saying
that Ford is out of the performance picture for the time being?
I think there's been enough publicity for those cars that if those
makers _don't_ put them out, people will be really pissed off and you'll
see a bad ripple effect. I also think the bean counters realize that.
Dodge still has the Challenger on its web sites as "coming soon". If
Dodge makes the Challenger and Chevy doesn't make the Camaro, Chevy will
take a spanking for it.
Cobras certainly are kick-ass cars, but I still think you have to
acknowledge cars like the 300C, Magnum, Charger, and of course the
venerable SRT-10 (both Viper and truck). Overall, Dodge has the most
in-your-face attitude with what they've offered in recent years. And it
all goes back to the Neon SRT-4.
Guess we'll have to wait and see... ;)
Musatangs have had their warranty issues just as much or even moreso
than the other makers. There are plenty of bad memories to go around
when we start talking about intake plenums, Cobra specs, etc.
This is where Ford needs to wake up and smell the coffee. They've got
the 450hp Harley F150, but nobody knows about it, and it's limited
production. Hello, marketing???
Speaking of blown motors, that's a nice setup. Saleen inverted twin-
screw running 6lb of boost on top of a 5.4. Bump the boost a bit and
you're over 500hp. So there ya go, Michael. Screw Mustangs, it's time
for another blown F150.
Yes, OHC engines have some advantages. My point is, under NORMAL use
the advantages are negligable. The engines must be wound tight to make
use of most of the advantage - Horsepower alone tells only a small
part of the story. Today's AVERAGE car runs somewhere around 2000 RPM
at legal highway speeds in top gear.
Under NORMAL HIGHWAY DRIVING an engine with dual overhead cams and 4
valves per cyl has little if any advantage over a pushrod 2 valve
engine of the same displacement. It has NO advantage over that pushrod
engine in durability or longevity, all else being equal.
It has a definite DISADVANTAGE when it comes to cost to repair.
It is also at a disadvantage packaging-wise- as it is significantly
larger in virtually all dimensions than a pushrod engine. It is also
generally HEAVIER if made of the same materials.
Yes, many high output OHC engines are lighter than the equivalent OHV
engine, but just because the "low tech" engine elected to stay with
cast iron heads and block instead of the aluminum used by many/most
OHC engines for at least the heads, and most often the blocks.
That said, today's thin cast iron blocks suffer only a small weight
penalty over the average aluminum block of only a few years ago.
So - if you are talking no-holds barred performance engines, and
maintenance/repair costs (as well as production costs) are a secondary
consideration - yes, OHC engines have an advantage.
DOHC has a marge larger advantage over SOHC than SOHC has over OHV
technology when you get into the higher output higher speed engines
because variable cam geometry is so much easier on a dual cam setup.
This does NOT make a pushrod engine necessarily a lesser engine for
some 90+% of owners and drivers.
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Truth be told we could all get by with three cylinder shoe boxes for
basic transportation. People don't buy high performance car because
they need them. ;)
I disagree with the above. With VVT, multiple intake and/or exhaust
valves, dual tuned runners etc. the power band can be enhanced from idle
to redline. In the OHV engines I have run to high mileage the bigest
chance of parts failure has rested with the valve train. It can be a
ticking lifter, bent push rod or a bum rocker arm. IMO, these
components are the Achille's heals for OHV engines. They don't exist in
an OHC engine and therefore con not be the cause of failures. The
durability of Ford's 4.6L is legendary already and I chalk a lot of it
up to the OHC design. Fewer reciprocating parts mean greater
reliability and longer life, IMO.
I will give you that OHC heads are more a throw away part the their OHV
counter part. That being said the infrequency of early catastrophic
engine failure in today's engines (OHV and OHC) makes this a minimal
issue. If today's cars are maintained well engine failures are few and
I agree. But I think we also both agree that for high performance
applications OHC engine have inherent advantages that OHV engines can't
match. Remember the 427 SOHC engine Ford had in the 1960s? The OHC
design made it one of the best engines of that era. It was the only
engine that NASCAR banned because it was eating the Hemis alive. The
OHC design made it too durable to run with push rod motors. This also
reminds me of the only turbine car to run in the Indy 500. It bitched
slapped the entire field of cars that year until its gearbox failed with
two laps remaining. I wonder what we would have in today's cars if they
hadn't banned the turbine and SOHC engines? At a minimum I think we
would have seen OHC engines in production cars much sooner.
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