H/Boss Engine OHV!!!

[MustangFanatic]

Fourcam over at SVT Performance just confirmed today that the new H/Boss engine is indeed an OHV design. I've only included the actual post where he confirms and the original post but feel free to read the remaining 28 pages worth of debate on the next gen Boss. Fourcam has proven in the past to be very accurate with his information but having said that this is the internet so everything should be taken as a rumor until confirmed.

 

IF (and I stress if) this rumor is true, how does everyone feel about the development? I'm undecided at this stage having owned both OHV Small-block Fords and Modular powered Mustangs, each has their own strengths and weaknesses. Certainly many would feel this is step backward from a technology perspective but from someone who owned several OHV small block powered Ford's, that design has plenty of potential for big HP and torque . The most exciting development is the over-square design and a larger bore spacing than the current modular creating a robust platform for performance applications. At the the end of the day, if this new motor makes more power than a modular with equal efficiency and greater performance potential, I don't care what valvetrain design is used. Let the debate begin...

 

http://www.svtperformance.com/forums/showp...amp;postcount=1

 

http://www.svtperformance.com/forums/showp...p;postcount=676

[MustangFanatic]

Further update from Fourcam - it appears the modular may live on in "revised" form...

 

http://www.svtperformance.com/forums/showp...p;postcount=706

[68fastback]

Hi Steve, I just asked Fourcam (on SVTperf) if he'd take a look when he can at the SU thread where I posted the various engine intake-offset pics and see what he thinks in that context. I can only see OHC in those looong intake-offset pics, but he may see something I'm missing.

 

Dan

[robertlane]

For the next-generation Boss, Ford will revive the Boss 302 (5.0L). Don't think about old or current architectures though.

[MustangFanatic]

For the next-generation Boss, Ford will revive the Boss 302 (5.0L). Don't think about old or current architectures though.

 

Robert, exciting news indeed - just wish it was coming before MY '11!! I've been waiting a very long time to get behind the wheel of my very own Boss 302!!

 

Dan, thanks for linking up with Fourcam, seems all available information is telling the same story - a it's a great one - Boss 302!!

[robertlane]

Yes, it's going to be a great, long awaited and overdue introduction! I think Ford is absolutely doing the right thing by bringing the Boss 302 back. The downfall is that so many cool Mustangs are coming back and I can't afford them all.

 

What is one to do? Boss, Shelby GT500, Shelby GT350, Mach1....... Damn you Ford! Damn you!

 

When was the last time a Mustang fan could have so many choices?

[monzter]

When was the last time a Mustang fan could have so many choices?

 

I guess 1969..when we could choose the regular mustang..351 V8, 428 Cobra Jet V8, Boss 302, B0ss 429 and i'm sure i'm missing some other model.....sure looks like we're heading in that direction again. Can't wait...

[68fastback]

For the next-generation Boss, Ford will revive the Boss 302 (5.0L). Don't think about old or current architectures though.

 

A new architecture ...at 5.0L?! Not old, not current. Leaves only the H/Boss ...or a small new motor different than the H/Boss (?!!). Now I'm getting very confused by what you said, Robert. Help! Is this like a refreshed mod as opposed to the H/Boss or just a 5.0L H/Boss or??????????????????????????????????????????? ???????????????????????????????????????? ?????????????????????????????????????????? ;-)

 

I ask that because I see FRP is now offering two 5.0L blocks based on punched 4.6 DOHC mods -- one seemingly conventional, and one made of that super tough 'diesel-blend' iron ...like the redux Boss-crates shown at last years's SEMA are using (and different than that bullet-proof alloy 4.6 DOHC "aluminator" block).

 

I'm convinced the Roush-Bowles yellow-mule is an SOHC H/Boss even though there's been some recent 'saw-it-up-close' info to the contrary (which makes no sense to me if it was the same motor in the HRM pics).

 

Then today BlueII (BOF) says the Roush-Bowles is absolutely positively take-it-to-the-bank OHC (which I totally agree with and have been saying since Sept based on the vintage FoMoCo engine pics/comparo I posted.

 

Robert, any additional insight or clarification you can share?

 

Hmmm, maybe SEMA this week will have a big surprise?!

[moabman]

Now I'm confused too! I thought the mule was running a 7 liter displacement NA OHC engine not a 5 liter. I don't think they would share a common block. Explanations welcomed

 

And what is that coax cable in the photograph for?

[68fastback]

I think there's a 'revised' modular at 5.0L (via bore). My hunch (dunno) is it's just a punched 4.6 DOHC but with a much-strengthened block (as in the special-iron 4.6 FRP is now listing) to prevent bore-distortion at high output in a production-life context, but it seems others have thoughts/info that it's a substantially more 'revised' mod (which makes no business sense to me).

 

The Roush-Bowles mule is the debated OHV/OHC 7.0L (clearly OHC from the MMFF & HRM pics to my eyes).

 

What is also confusing things is that apparently Roush was testing an OHV version also (never saw a pic of that tho).

 

So, based on the research/analysis I've done and the posts here At SVT and BOF, I think we're talking about:

-a truck H/Boss (not to be called BOSS) with OHV or OHC (dunno but, astonishingly, that's the one everyone seems to agree is OHC!)

-a BOSS-mustang 'revised' modular 5.0 DOHC

-an H/Boss OHC hi-po motor coming, in alloy too

 

Mark, see if you can make better sense out of it -- I think there's just a lot of discussion that's actually talking about different engines.

 

Here's the links to the various discussions I've found:

 

SU 7-liter thumper thread

 

SVT-performance OHV/OHC discussion

 

more SVT discussion later in thread:

 

BOF (blueII, etc) saying for sure H/Boss in Roush-Bowles mule is OHC

 

 

...and this one is internesting: GM 4V pushrod heads by arao engineering -- a foreshadowing or an abberation? note that they are using the term "LSX" on their website -- a registered trademark of GM! ...that can't be an accient, imo - maybe it's like microsoft's approach to testing products -- do it in the field <lol>...still, an interesting approach.

 

One things for sure -- this will all be very interesting and I'll keep my eyes peeled at SEMA.

[MustangFanatic]

For what I'm hearing, Ford is evaluating both an OHV and a OHC engine for production - and the OHC engine is not the H/Boss and would not share much with the current modular family other than a similar displacement - 5.0L.

[07SHELBY GT]

I don't know if it matters to you folks,Roush always said that he would NOT have abandoned the pushrod architecture as quickly as Ford did,Restating some of the previous facts would be useless but pushrod motors DO have some advantages.

[68fastback]

Possibly there are different pictures and vintages of information that have gotten confused recently.

 

I think the 5.0L 'revised' mod and the 'experimental' 7.0L H/Boss (pictured recently by HRM and MM&FF) in the Roush-Bowles yellow mule are both OHC.

 

Possibly an OHV engine was also evaluated (dunno and I've never seen a pic of one) and possibly even the production engine will be OHV (though I sure hope not and seriously doubt that).

[MustangFanatic]

Dan, I'm with you there - every published pic I've seen suggests an OHC valve train structure. I don't believe we have yet seen a pic of an experimental OHV engines (not to say that they don't exist, just that they haven't been documented)

 

However, Fourcam is noted for his connections and accuracy of the information he disseminates. I seriously doubt he would "publish" his information if he didn't feel that it was reasonably accurate - he wouldn't want to risk damaging his reputation in the online community as a knowledgeable resource.

 

I'm not opposed to either structure, OHV or OHC - I just want to see Ford step up and offer a V8 engine with serious naturally aspirated potential - something in the neighborhood of 400 - 450 hp without artificial respiration, with good low speed torque and ability to rev. Frankly I don't care which valvetrain arrangement as used as long as the objective is achieved.

[68fastback]

Yeah, that's the quandary since the pics were OHC and fourcam's info is typically excellent ...but so is blueII's.

 

Lacking an OHV pic, a description of some sort would be nice, i.e. did it look somewhat like a vitage FE ...were the valvecovers 'refined' pieces like the "experimental" OHC pic ..or were they vintage-like stampings, etc.

 

I actually do have some strong preferences depending on the displacement square-point. The modular's square-point is 4.6 so would have to be only 3.5L or so to be a nicely oversquare NA screamer. Emissions considerations aside a small displacement NA like that would do fine on 2 valves and, therefore, pushrods would do just fine, imo. But start going severely undersquare with long strokes at 5.4 and it needs 3 or 4Vs to breath with the relatively tiny bores.

 

If we want to see an NA screamer as a redux Boss 429, then it needs to still be nicely oversquare at that displacement to breath with 2-valves. At roughly FE-spacings, I think three valve OHC is indicated.

 

Then, add emissions and CO2 considerations and the ability to do really effective VVT/VCT/GDI/2-plug/DoD all in the same motor and pushrods start to reveal their prehistoric inappropriateness, imo.

 

I realize the above is the 20,000-foot view, but just wanted to try to concisely state why I'm solidly an OHC bigot ;-)

 

I think we should look for GM to also, and once again, sip from the OHC cup in the next 5 years or so.

 

<edit:> I've been searching the boards and still can't find anything to support that motor being OHV... sure hope it's OHC!!

[moabman]

The one thing I don't understand other than from a reliability standpoint is the reluctance to take advantage of the OHC's ability to rev. I'm not talking about a 10,000+ screamer but how about a 7500 or 8000 rpm machine?

[68fastback]

The one thing I don't understand other than from a reliability standpoint is the reluctance to take advantage of the OHC's ability to rev. I'm not talking about a 10,000+ screamer but how about a 7500 or 8000 rpm machine?

 

I think that's actually another aspect of square-point. At 3.5L or so (short-stroke oversquare) the modular would have the potential to really scream and exploit it's inherent DOHC hi-rev breathing in NA trim. It's just not practical to do that at 5.4 (undersquare and long-stroke/high piston-speeds) in a production engine with the existing bore-spacing. It's actually not a bore-spacing problem at all -- it's a square-point 'problem' diven by pushing displacement with stroke. The mods are square (bore=stroke) at 4.6L. The rumored 'revised' modular gets to 5.0L with bore, like the manracer, so holds promise for a nice NA 5.0-BOSS ;-)

 

The old FE was square at aound 7.5L (or more depending on actual bore/siamese-liners-in-alloy, etc) and the 385-series at over 8L (depending, etc.). The stroke on the 5.4 mod is big (for it's small bore) as big as the Boss 429!! Therefore the revs must be kept constrained. Therefore a S/C is used in lieu of more power-strokes/min (rpm). It's not because DOHCs can't rev. It's because a highly undersquare engine can't rev regardless of displacement. I mention it's not OHC realted because of misconceptions I've seen posted on various forums -- it has to do with the modular's design-point not anticipating the revised HP-wars, imo, and therefore having to push displacement via stroke to the point where it can't rev enough to exploit the DOHCs real advantages without a S/C and without compromising reliability or excessive costs of exotic materials. A short-stroke 3.5L DOHC modular might happily scream to peak power near 8K rpm with appropriate intake and cams.

 

That's why I'm so enamored with the notion of a large-displacement NA OHC 3V/4V H/Boss with a 7.5 liter (or higher) square-point such that destroked to 5.8-7.0L can actually exploit the high-rev breathing benefits of the multi-valve OHC design in NA trim. No reason why 10K (and more) in race trim and 7500 or so on the street would not be entirely reasonable without the need for exotic materials (expense) to keep it togehter ...and then cruise at 30mpg (also not unrealistic, imo) with VCT, GDI and DoD which would also seem best optimized in a 3V OHC configuration. My bias is that this is the future.

 

Small-displacement highly oversquare DOHC all-out road-racers routinely spin to over 18K rpm(!) ...and over 8K in dead-stock street trim. Of course some can afford to be even more oversquare beacuse the distribution of power-strokes on the crank of a V12 permit small rod offsets (short stroke) and still generate adequate torque with big HP up through the incredible rpm ranges of the racers.

 

The old 289s were quite oversquare at 4.0 x 2.87 and the 302s still nicely at 4.0 x 3.0 -- even the 351 was 4.0 x 3.5. One can only imagine what those engines could have unleashed with a multi-valve OHC architecture and stronger deep-skit castings like the modulars. ;-)

 

I find it interesting that the H/Boss's bore-spacing at an equivalent oversquare ratio of the old SB302 would displace in the vicinity 5.7L. A 3V (or 4V) OHC version of that would be killer in a Boss 351 for a Trans-Am redux or in NASCAR, for that matter (present OHC restrictions notwithstanding). In the 70s the Bud Moore prepped 351s turned around 8500rpm down the back straght at Watkins Glenn if I recall with 2 [canted] valves and pushrods! Not unrealistic, imo, for an oversquare 3/4V OHC deep-skirt H/Boss version with production bottom-end to make peak HP at well over 9K rpm and rev a half-gear's width past that with reliability PJ & GF could have only dreamed about.

 

I find the prospects of such an engine the most exciting powerplant since the birth of the mod and an ideal OHC application.

[MustangFanatic]

Excellent post Dan!! As always, I bow to your superior intellect and understanding of engine design dynamics.

 

Bottom line, is the current modular is constrainted in a max HP application because of it's inherent undersquare nature and not the valvetrain structure. From an engineering standpoint, certainly the OHC is a more efficient valvetrain design and my preference if I were to have the option to chose. The recent developments certainly give all of us reason to be excited about the prospects of both a serious Boss 302 street engine and a competitive large displacement NA V8....if we could only get them to market NOW!!

[moabman]

Yep, a great discussion of geometry and its effects in engine design. Now, if I understood you correctly, our 4.6 mod is square at that displacement. So why don't they push the rpm range? I know it can't do the 10,000+ but at square couldn't we get to 9,000 NA pretty easily?

 

The other question was: do the powdered metal rods prohibit getting to 8-9k? I can't believe Ford would go to the trouble of developing a square OHC engine and then limit it with a rod design. If the rods don't present a limit, why aren't more people experimenting with engine modifications to build power in a higher RPM range?

[68fastback]

Yep, a great discussion of geometry and its effects in engine design. Now, if I understood you correctly, our 4.6 mod is square at that displacement. So why don't they push the rpm range? I know it can't do the 10,000+ but at square couldn't we get to 9,000 NA pretty easily?

 

The other question was: do the powdered metal rods prohibit getting to 8-9k? I can't believe Ford would go to the trouble of developing a square OHC engine and then limit it with a rod design. If the rods don't present a limit, why aren't more people experimenting with engine modifications to build power in a higher RPM range?

 

Just my opinion, Mark, but I think you're right-on...

 

The 4.6 '01Cobra (DOHC) has less-robust cracked-powder rods compared to the ones in the Shelby 5.4S/C and is still redlined appropriately higher, at 6,800 with the revlimiter cutting in at 7,200. With a CAI and a custom Evo tune and the rev limiter off it pulls decently to about 7,800 -- though I told my friend he should not make a habit of that <lol> since cracked-power is reportedly stronger on compression than tension and I've read that the dominant force starts to shift from compression to tension a bit above 6K in a typical V8 (undoubtedly a generality but a valid consideration, imo).

 

I suspect if the 4.6 was [destroked to] a 3.5, that point would move higher still since, to my mind, the less stroke-generated piston-speed, the more rpm are possible at the same piston 'retrieval' force (rod tension). I've never seen that specifically considered, but it would seem rather axiomatic if the limitation is rod tension. Consistent with that, even the Ford GT with H-beams is redlined at 6,500 compared to the Shelby's 6,200 likely because of the high piston speeds and attendant 'retrieval' forces. Again, just my take and there may be other considerations making it not worth pushing it further, like S/C bearing limitations of 14,000 rpm in a factory motor having to pass a Ford 150K cert, etc.

 

In an all-forged H/Boss BOSS 351 (nicely oversquare and with fairly light production forged-aluminum short-skirt pistons) that 'crossover' point even with forged cracked-powder might make a factory redline of 7200-7500 feasible (dunno) and nothing says Ford can't use a forged H-beam depending on the rules and engine homologation requirements for a 'factory' TransAm series. If that's the case, Ford will still have it's work cut out if GM successfully homologates some of the 'vette titanuim goodies in the Cammy, but even then, the superior multi-valve breathing should be able to give up a few power-strokes/sec to a poorer-breathing but titanium-revving 2-V pushrod motor and still kick butt.

 

I don't even want to think about what an all-out H/Boss racer with similar titanium pieces could be capable of ;-)

 

Many generalizations and prematurities in the above, I realize, but it's fun to 'pre-paint' some straw-man images of where this might be headed.

 

Even in the 60s, wedge-head pushrod 427FE deep-skirt side-oilers racers ran routinely to 8,500 rpm with what would be considered non-exotic quality forged pieces today, so I'm hopefull a more oversquare OHC H/Boss would be formidable -- and probably why the old SOHC 'cammer' was banned across the board.

 

If Ford goes this route, I can't see any true ponycar series sanctioning body (i.e. not some bastardized NASCAR Busch-series push-down chassis with a ponycar-shaped CF body) banning the only continuously produced pony car. Maybe I just inadvertantly defined what will cause there to be more than one pony-car venue?

 

<edit:> admittedly we haven't cnsidered a lot here.. deck height can also affect piston-speed/dynamics/side-loading/piston-height for a given stroke and even bore spacing can indirectly affect this ...smaller-diameter but wider crank counterweights permit lower deck-heights which permits shorter rod lengths and more compact packaging for the same stroke but at the expense of piston-speed -- not as much a problem for oversquare engines within the limits of how short the piston can be stable in the bore and still clear the crank weights, etc... and I'm sure there are many more engineering considerations I know little or nothing about)

[Alloy Dave]

Dan,

 

Sorry if this post is a bit out of place, but it seemed to fit somewhat here.

 

I admit I don't really understand this engine, but thought you may have read about it or be interested.

 

Something to keep you busy for an hour.

 

http://www.sandersonengine.com/

[68fastback]

Cool design, Dave! ;-)

 

Carroll Shelby also has been involved with a unique internal combustion engine, the OX2

 

So many designs look good but I think the traditional IC engine is here to stay :happy feet: ;-)