Making your V8 a big four....

[Ron Earp]

About 10 years ago I was living up in Virginia and I knew a fellow that was a long-time Ford mechanic and part-time engine builder machinist. Those guys just race roundy-round tracks in the dirt, as is customary in the South, and he showed me a really neat motor they'd assembled some years before.

Basically, it was a SB Ford with a special crank and cam that essentially made a big four cylinder out of a V8. Purpose - well, I don't remember what he was telling me but I'm sure the theory didn't hold out since we don't see these conversions today. It ran, sounded like hell on wheels, and was pretty cool for a conversation piece in a large shop with space for conversation pieces like that.

Anyone know about these things, the purpose, and if they're still in use or sale? He told me he didn't make the crank and cam, they were purchased, and I don't remember how the firing order was or anything like that. That is actually what I'm curious about is the firing order - did it do a (1-7), (4-6), etc.

Any info or comments would be appreciated.

 

[Rick Muck- Mark IV]

Ron,

I understand that this is still done for midget Sprint cars. They use a purpose built block and crank with a Ford NASCAR type head and rods. Ed Pink builds them I recall.

Not as wild as the 300 CID Ford old pushrod 6 cylinder I saw a the Columus Ford swap some years ago with a head made out of TWO Boss 302 heads cut and welded. The Windsor/Boss series share bore centers and head bolt pattern with the 240/300 six series. Made the motor for Bonneville as I recall...

Rick /ubbthreads/images/graemlins/grin.gif

Rick

 

[roaldin]

Sounds to me like you're talking about a 180 degree or "flat plane" crank.
Most really high performance V8's use them now. The DFV for instance.
There's a bit about them here web page .
There are a few other advantages, eg it allows the use of shorter primaries on the exhaust (if that's what you need) because they don't need to crossover.
It's really two big fours.
Apologies if I've misunderstood your query. If you haven't heard of them before then look them up using "Flat plane crank" and you'll find more info' than you want to know. /ubbthreads/images/graemlins/smile.gif
They lose the V8 Rumble and sound a bit ordinary at low revs but they scream when they get going.

Tim.

 

[Ron Earp]

Nope, I know about different interval cranks and this wasn't it. As I remember he was talking about torque output and power pulses for flat tracking, it was definitely a "big bang" concept V8. It had split wires for the plugs with some terminals off the rotor, that is not used. It vibrated a bit more than usual and definitely didn't sound like a "normal" V8 or a flat crank 8.

To me it is almost certain this thing wouldn't offer any advantages but then again, there it was. He wasn't a driver, just a builder, and my impression was he thought it was POS but didn't really say that. Could have been a one off, but I remember him saying it was something you could purchase and named a company. Of course, he might have been referring to a machine shop in the next county that made the blasted things, I just don't know.

 

[Ron Earp]

Hey, MK-IV missed your post, sorry. I will check that out as that sounds like the ticket.

 

[ChrisL]

Ron,

Most 500cc Grand Prix motorbikes were using the “big bang” configuration in recent years. For those who are unaware, “big bang” is when alternating cylinders are on a synchronized stroke, ie. firing together.

The advantage was not horsepower, indeed I think they even sacrificed some. The advantage was in tyer grip under hard acceleration. The theory goes that a tyre will break traction momentarily with each firing of a cylinder, so if the time between each firing pulse was increased, the tyre would be given time to regain traction before the next pulse. The vehicle would therefore be able to accelerate harder out of corners and also give the rider (driver) more control.

I’ve never heard of this theory being applied to anything other than motorbikes, but I suppose it should hold true for any type of vehicle, especially in dirt where grip is more important that horsepower. Incidentally, the Moto GP Ducatis are said to have that same advantage simply because they are running two cylinder engines, compared to their competitor’s conventional 4 cylinder engines.

 

[roaldin]

Which still sounds like a flat plane to me. Each cylinder has a twin that fires at the same time, thus "a big four cylinder". There is a torque advantage promoted for this system. Vibration is an issue (discussed in web page above).
I'll go away now but it all sounds too similar to me.
I have seen a Cleveland with an "off the shelf" flat plane and companion cam in it. It went well but sounded appalling. They need about 8000 rpm before they start sounding good. /ubbthreads/images/graemlins/smile.gif

Seeya

Tim.

 

[roaldin]

Actually rereading your second post Ron, it has to be flat plane. If it's running two leads from one post (meaning four used, four unused) and therefore firing two together making it "a big four", then it has to be.

Tim.

 

[Ron Earp]

Yes, you are correct I'm wrong and I'm confusing the issue then. This is exactly what it is and I was messing things up by confusing firing and crank angle.

So, the thing ends up being a big four firing two pistons at a time as do Ferrari V8s and a whole bunch of others, including I think the Lotus V8. No way this thing would ever be as smooth as a 90 degree V8, at least, I don't see how it could be.

Any in practical use other than the Sprint car example above? Maybe it isn't so bad after all, it could lend a pretty neat sound to a GT40 at high RPM.

 

[roaldin]

To check it out DFV Animation site.
It is possible to have it fire two cylinders on each bank together to get a "big bang engine"
This fits the bill for having a different crank, different cams and the other stuff. It's also make it rough.
Wouldn't it also be possible to fire two together on a conventional engine with just cams and a normal 90 degree crank, or have I forgotten something (after all it's only 4.10 AM). /ubbthreads/images/graemlins/crazy.gif
Sorry if I'm confusing the issue. You got me interested. /ubbthreads/images/graemlins/smile.gif

Tim.

 

Some years ago there was a very inovative guy that I knew (now deceased) that built one of these engine using a Ford flathead V-8. He called it a Crossfire and it went like stink! Another neat project was a 2 cycle Chev V-8. I never saw or heard it run as I was off to the Navy and upon returning lost track of the guy. I heard he moved to Florida and passed away a few years back. Some fellows said the the 2 cycle Chev ran and that is all I know of that project.


Vic

 

[ChrisL]

Here's a thought.

If a "Big Bang" V8 = a 4 cylinder engine,
does a 2 stroke V8 = a 16 cylinder engine?

OK I'm just being silly here /ubbthreads/images/graemlins/tongue.gif /ubbthreads/images/graemlins/grin.gif

 

It might act a V-16 as it has more firing pulses, plus taking in more air and fuel.

Vic

 

[Chuck]

Vic,

Smokey Yunick was playing with those odd fire and unusual motors. I'd guess that is who you were referring to. Ran a shop in Daytona and would show up at NASCAR races from time to time with a rule bending car. Was always rumoured to be getting back door money from auto makers to try new ideas in engine design. There's a pretty good biography on him out there.

Chuck

 

[Jim Rosenthal]

I don't think there are 2cycle gas V8s out there, but there are 2cycle 2,3,4,6,V6,V8,V12 and V16 diesels. They were built by Detroit Diesel and there are literally millions of them around. Interestingly, even though every piston downstroke is a power stroke, they do not produce twice the power for their displacement, and certainly not for their weight; there is the power loss of driving the Roots blower that pressurizes the airbox, and the fact that 2cycle combustion is evidently inherently less efficient than 4cycle. Even in a diesel, where you always have, at least in theory, more air than you need to burn the fuel you inject. ALL modern high-speed diesels are 4cycle, and the power/weight ratios are getting impressive (as well as the overhaul costs because they've got the wick turned up so far with high turbo pressures etc etc)