4.5 in (114 mm) bores are probably about it for complete flame travel with gas. Pro Stockers seem to be in the 9-10k range with those bores. To me that's harder to take than maybe 19k from Ferrari or BMW.

F1 are probably 93-97 mm bores (they don't say). I'd guess that flame travel isn't the problem. Remember they can get 3 L with any number of cylinders.

My guess is that they have developed 250-300 cc cylinders for optimum flow at crank speeds in the 15-19k or so range. Who's to say someone won't try a 12 with 250 cc/cyl and 20k+. We think our OEM engineers are restrained; F1 packaging and desire for light weight, low CG engines makes our OEM limits look easy!

 

I'm waiting to see about CVTs when they can build one to hold up to real power. In terms of power you won't need VVT or VTEC or even multi-cams because all you'll need is an "all or nothing" cam like the OHV design offers. One cam for peak power at one RPM and that's all, the tranny does the rest...to a point anyway. Even the weakest of motors could be insanely fast.

 

theres a much easier way to do that, when they develop batteries that can do the job anyways.....

useing a very powerful electric motor, because they have a perfectly flat torque curve. an electric motor that has 400ft/lbs will have it at 1rpm or 20000 rpm. chrysler built a crazy electric intrepid i think it was, it had like 400hp but the batteries lasted like 10 minutes.

 

If I'm not mistaken, our mutal idol Chuck directed him this way. Great minds associate together

Hmmmm.....then what the hell am I doing here?

 

So the cam in an D/OHC motor needs supports and bearing surfaces - just like an OHV motor. Only difference is the supports and bearing surfaces sit on top of the head/s opposed to in the block.

D/OHC motors usually only run one timing chain or belt - just like an OHV motor.

An OHC motor runs one timing gear - just like an OHV motor. Of course the number of gears required "increases" in "V" and multi-cammed motors, but since when is timing gear failure such a high liability?

FWIW, my beater SOHC '86 Honda has yet to experience any valvetrain failure - or any failures period for that matter, in 210K miles. On the other hand, 2 out of 3 LS1 owners around here have all bent pushrods at some point or another Same goes for my good ol' LT1

As far as the front of the motor being a mess, only difference between an OHC and OHV motor is a longer chain/belt connecting the crank to the timing gear/s.

But who the hell really cares? The bottom line is OHC motors are far less complicated and far more reliable than the die-hard traditionalist is willing to acknowledge and OHV motors hinder power far less than die-hard ricers are willing to acknowledge

 

To some degree yes, to some no. I can get a cam from Isky, Crane, Comp Cams, Shnieder or several other companies for my 1973 car, and it costs less than $500 for a cam swap including new rockers/lash pads etc etc

Since some of the newer cars are not as often going to be raced, there may be a smaller market to actually pedal cams to since many 'kids' dont tear that far into the motor themselves, and power consists mostly of stickers, nitrous, or a turbo, so kits may well be VERY pricey for newer cars.

 

I didn't check the link yet, I thought I already posted the info in this forum on the Coates spherical rotary valve engine (it was designed before thier time, just not perfected).

www.coatesengine.com

Coates International Patents US Patent 4,944,261, issued July 31, 1990, "Spherical Rotary Valve Assembly for an Internal Combustion Engine".

 

Honda built a 250cc V8 bike engine that did 22,000 redline, long ago (early 80s I believe).

The cam sits over the rockers, and the rockers touch the lash pads (insignificant piece in terms of weight/size), thats it. No pushrods, no heavy lifters, and a much more aggressive opening ramp that almost is flat. The rockers are the wear surface, and those are replaced at the time of your cam swap for fresh 'wipe' surface, $100 for my engine. I also happen to have a dedicated oil spray bar over the assembly, instead of just random oil being sprayed out onto the valve cover ceiling.

 

I saw an electric car on Tech TV that ran 12s (was beating Vipers), but looked like crap, seated one only, and was around $70,000

 

You guys are missing the point. DOHC, VVT… can be used to make power, but in the engines we’re typically talking about they are unnecessary to do it, and the extra expense will not be justified.

For example, let’s take our typical 350 v8. Assuming 100% VE (which isn’t going to happen, but for the sake of argument) at 6000rpm the most air it will ever pump will be 608cfm (real world, it will probably have a VE of 70-80% and only use that much of the 608). To feed each piston that works out to be 220cfm per port. That’s less then what a set of box stock vortec heads flow, and could be easily gotten from a set of mildly worked lowliest heads made in the last 20 years (ex, a set of LG4 heads could do this with a good valve job and a bowl blend). Assuming that the cam, intake, exhaust… is matched to this rpm range, putting bigger, better flowing heads on it will make little if any additional power. The heads on there already flow everything that the piston moving up and down in the bore can pump. BTW, assuming 80% VE, this head setup with the right cam and other parts should be able to rev to about 7500rpm and make a HP peak of about 450hp at around 6000rpm. If you suddenly found a set of heads that flowed 300cfm and slapped them on, you’d have to change everything else to work well into the 8000rpm range to even use 300cfm flow. At this point we’re already way outside of anything that a manufacturer would bother trying to build, if they really need that kind of HP, they’ll build a big block and spin it 2K rpm less, costs much less and is much more reliable.

Now the reason that it doesn’t happen in race setups is mostly 2 fold. First, on some level, the race setups still emulate factory setups, they may not use any factory parts, but for rules, sponsorship… reasons they do for the most part keep basic factory layouts (I’m not sure what F1 and similar setups have to do with this, these are much smaller engines then we’re talking about, an f-body with a 3L that has to rev to 17K to make power would be a dog to drive on the street and never pass emissions). The second reason is that it’s unnecessary. Top fuel cars are not limited by power produced, they are limited by what you can build a clutch and tires to hold. They can’t use the power that they’re making now. If they accidentally release the clutch too quickly they blow off the tires and kill their run, if they accidentally release it too slowly they kill the clutch and kill their run, it’s not a question of HP, they’ve got more then they can use.

This leaves the question, why would ford build a DOHC V8 for their production car line? Well, not because it was necessary from a technology standpoint. It’s much the same reason that the new Cobras (and many other sports cars) come with 17” or larger wheels. During development ford found that the car was fastest on a road course with smaller diameter wheels (assuming similar compounds and contact patches), but marketing took over with “no one will take a performance car seriously that comes with less then 17” wheels.”

Domestic auto makers have a problem here. They’ve got a perfectly functional, reliable design that makes more power and gas mileage then they need. Switching to OHC makes things more complicated, expensive and much harder to package with only a minimum advantage, which could real world be made up in tuning. The problem is that there is a segment of the ‘automotive enthusiast’ market that look at their ‘primitive’ pushrod engines and say something along the lines of “why would I buy stone age technology?”

The problem here is that people are stupid sheep, not that sticking to pushrods is hurting their car's performance.

 

ya, but there are at least 2 cams in a v8 is what im saying, so there is more hardware required.....if it was easier and simpler then it would be cheaper and would already be commonplace.

also, bent pushrods on 2 out of 3 ls1's ? your high on something pal, there are about 25-30 guys i hang around with driving ls1 f-bodys and none have had any problems, nor have i even heard of that problem. my brother is a tech at the local dealership and he said that problem shows up once about every 3 months there.

your 210k mile honda isnt a race car, so thats not really what were talking about....talkin about the benefits for a race engine

 

"Now that's an eye opener! Not everyday you see a motorsports professional's resume on the internet.
Nick, what brings you to an f body message board? Just my curiosity running abound.... hope you'll be sticking around!"

As Jim S. mentioned, it seems we have a mutual friend in Chuck Riddeck. I started checking the board out at Chuck's request here over a year ago. I consider him a good friend and we consult each other from time to time on various issues. Chuck has actually worked with us on many of our prototypes and is currently working with Ian Bisco with their Nascar engine development team.
Most of the threads here are found with satisfactory answers and thus I'm not much compelled to make an answer public most of the time. Hence, I believe I have 10 posts to my credit. As you can imagine, time is a commodity I don't have much of. Nor is my knowledge of your V8 engines. They aren't exactly my forte. I may pop in from time to time but I'll be about as regular as a chap on a peanut butter and cheese diet.

"Nick,
Are you in any way involved in Cosworth's CART or Nascar programs? Just curious."

No sir, the Nascar program -in the states- is under the direction of Ian Bisco. The UK team is headed by Bruce Wood. I wouldn't mind working directly within that effort but I am already spread thin as it is. I'm limited to consultation on the most part of that endeavour. Although the program does provide a rather unique challenge, mainly in the form of the pushrod valvetrain kinematics, it's not something I would mind tackling.

In F1 engine development we have surpassed most concerns in terms of valvetrain stability. Our main focus is in the area of weight reduction in the piston assembly. Aluminum beryllium alloys have been outlawed but with that came a new statute, that the material has a specific modulus of elasticity of 40 Gpa/(gm/cc). With that we have gone on to produce a metal matrix composite -an aluminum/ceramic alloy- for our pistons that is very near in weight to the aluminum beryllium alloy of old. One-third that of your SAE 4032 forged piston. This material has also showed promise as a poppet valve material as well as a cylinder liner. Allowing the development of a dry liner and an even smaller sectioned crankcase.
Much of this is now common knowledge so I can say it here. Of course there's much more that I cannot. Needless to say, material science is playing a big part in engine development today and with bmeps in the 17.5 bar range at peak power, we are making more power then we would have ever thought possible ten years ago. You'll just have to wait and see what the future brings.

Cheers,
Nick Hayes

 

It actually is commonplace - just not for The Big Three OEMs.

Just stating the facts. What I smoke in my own time is my own business Honestly, 2 out of 3 LS1s in our local car club bend pushrods at some point or another. But then again, most of them can't drive either The cars your brother the tech services probably aren't driven nearly as hard.

I'll take that as your way of saying, "Yes, OHC motors can be just as reliable as the good ol' pushrod motor in production cars"

As for race motors, the valvetrain is rarely responsible for motor failure in racing series that run OHC motors - in other words just about all sactioning bodies other than NASCAR and NHRA-type stuff.

 

Well, there are quite a few street engines in excess of 100% ve... so it does happen. Granted, you'll usually see better numbers from the tuned runner intakes like the Accel Super-Ram but it does happen with the shorter runnered Vic Jr, HVH1000's and the like.
I think much of what you said is off the mark, mainly because it is grossly over simplified. No inertial effects, no frictional losses, no bueno.
I don't see any OEM going back to a big block. The trend is towards lighter more efficient engines and a big block aint it. Most of this has been about eliminating losses and I think the biggest brakthroughs will come from some form of valve actuation. BMW is a good company to look at there..... they probably set the standard in innovation. As Nick stated, all that glitz has a cost and may not be practical for a more reasonably priced performance car. Tech is getting cheaper all the time though, so we'll see.

Nick,
Thanks for the feedback. We don't see Chuck much around these parts anymore. I'm sure he's busy... just got a set of cylinder heads back from him though, and they're here way before schedule. They are literally works of art.... I don't know whether I should use them or build a display case for them.
Hope ya stick around sir.

-Mindgame

 

By the way, Joe Sherman built a carbed 302 Ford here some time back. That motor never made less that 100% ve with either the Edelbrock Performer or the Vic Jr. Used some rather unorthodox methods in the building of that engine.... pistons facing the wrong direction etc., but the bugger made over 400 hp. Nothing to sneeze at.

-Mindgame