Lets not forget TVR and Lotus flat plane V8's.

 

The Champ cars (CART) are still flat cranks. 2.65L turbo V8's with anywhere from 700 to 1100 hp revving close to 16,000 rpms.

 

Ever look at the headers on an old (60s era) GT-40 race car? They cross over half the tubes from one side of the V8 engine to the opposite header collector. Like SStroker says, you CAN make a traditional (non 180* crank) V8 have even exhaust pulses for better exhaust scavenging if you cross over the appropriate primary tubes to the other side's collector. The engine used in the GT-40 did not use a 180* crank. They got the exhaust pulses evened out by doing very creative and complicated plumbing with the exhaust primary tubes.

What's a better way to go? I have no idea.

What I DO know is that high-winding, high output motors LIVE ON EXHAUST SCAVENGING TO MAKE POWER. While stuff like this is almost certainly not worth the expense or hassle on a street motor it's like the Holy Grail for a race motor. Anything they can do to improve it goes straight to the rear wheels.

 

Yeah, Ford tried a number of exhaust combinations on that engine. That may have been one of the first uses of "180 degree" headers on a 2-plane crank V8. Off hand I can't remember an earlier one. Anyone?

F1 V10s don't use crossovers. IMO packaging is one reason, but 5 cylinders can be tuned fairly well. Interestingly, at least one F1 engine has the exhaust pulses entering the collector in sequence; 1st cyinder at 0 degree(*) position on the collector, next cylinder to fire at 72 *, next at 144* etc. This should give a swirling exhaust stream. My guess is that it's for aero as the headers dump upward just forward of the wing. So, would one side swirl clockwise and the other counterclockwise? I think so to perhaps help minimize span-wise flow on the wing. Hmmm, when they race in Australia, do they reverse the rotation?

Current Cup and ProStock headers, from what I've seen, are 4-2-1 (Tri-Y), not 4 into 1. There's not much in the popular press about that, but there is visual evidence on TV, at least on Cup cars. 4-2-1 tunes well when it's done correctly, and it's very old, but good technology. My take is more average torque over the usable rpm band. At Martinsville that looked like about 4500-9000 or 4700-9200 if we can believe the telemetry. Combine that broad torque curve with a good traction "advisory" system, and you could probably dominate such a track. I'd like to know if plate engines with a 300 rpm power band also use 4-2-1s.


Newest Car Craft (yes, Car Craft!) has a fairly good header article by Jim McFarland. Some of it is very basic, but check out the primary pipe diameter/cylinder size/torque peak rpm equation. We have found it to pretty much hold true.

 

They actually changed the cranks to flat plane for IRL to sound better. They lose power with the flat plane cranks although the headers do work better. I think the firing order hurts a plenum style intake though where the 90 degree cranks work better usually. You can run a 180 crank in prostock too and almost no one does.

 

OldStroker,

Pretty much all of the higher end header companies use the rotating collectors sequencing. This has been done for a long time and is worth a little power. You are also right that there are a lot or tri-ys in PS and WC.

 

Warren Johnson tried the falt cranks in pro stock back in the late 80's. If my memory serves me he used the engine at several events and it did fairly well. When he stopped using the engine, I remember an interview with him where he was asked about it, he said that the engine had more potential. He has never used it again in an event since. Maybe not as much potential as he thought.

Also on the 4-2-1 headers. I can't speak for nascar, but the current pro stocks that I was able to get a look at recently (Dallas) were not using that style. They did have the tuned "merge" style collector. Similar to a megaphone.

My .02 pesos

 

The reason they don't use it in higher displacement motors is because of the insane vibrations. I remember BMW and their M3GTR project which ran a flat plane version of their M5 engine in an M3 body, the engine made plenty of power, but it also did vibrate a lot. One reason you don't see large displacement flat plane crank V8 engines.

 

Ferrari uses flat crank v8's. The biggest problem with a flat crank 90 degree v8 is the vibration. It is horizontal which will shake a car sideways compared to virticle with a clocked crank.

 

Its a bit off topic, but I wasn't sure where to place this. I've seen pictures of older cars (50's-60's era??) Where they have two engines, sometimes more. When they connected these two, how do they orient the cranks?
I've put up 4 possibilities with flat and cross plane cranks.
The only example I see now is for modifed tractors, and I couldn't find any info on that.

 

I don't remember the WJ 180 deg engine but I do remember Larry Mogan experimenting a few years ago. It wasn't any better than his traditional setup but Grant Lewis did qualify at least once. The engines sound like a pissed off bumblebee. They appear to be reving higher than they actually are. Morgan would have it fired up in the pits and just whack the throttle a bunch of times to freak people out. I guess it was his version of the Top Fuel throttle burp.

edit: It wasn't a 180 deg crank, it was a revised firing order 15736842 sorry for the off-topic post

 

The 60s dragsters sometimes coupled the engines thru wide flywheels with starter ring gears meshing! I doubt that they oriented them, but if they did, it was probably to get a firing impulse about every 45 degrees. With 153 or 168 tooth flywheel ring gears, the math doesn't work out too well.

Tractor pullers often have torque converters or some kind of coupling that slips so orientation doesn't apply. If one or more engines "poop the bed" the others just keep on pullin'.

If you were bolting two engines end to end, you'd probably try for even firing, not multiple cylinders firing together. Some of the reason a V16 is so smooth is the 45 degree firing order spacing.

 

Actaully the following picture is what made me curious to ask this (and exactly what you described).

I was thinking that also, that the engine would run more smoothly if they were offset with eachother. Initially I was thinking that the vibrations of the crank might interfere with that design, but it wouldn't matter if you are connecting the two with gears (duh! ).

Sort of makes me wonder...If you put a larger ring gear on one. The other engine would stay at a higher RPM at all times and offset the power curve. (Or tune them differently)
Probably a pain to get it to work that way though.
I wonder if I'd get slapped for recomending an F1 engineer cut his engine in two.

 

Some tandem twin engine dragsters in the 60s used two different engines, like a hemi and a SBC, for example. Most used identical engines up to twin Ford DOHC Indy engines. That's 64 valves! You could shape the engines' torque curves differently, but I suspect the few non-identical engine cars were mostly for effect. It's tough enough getting two identical engines to work together.

V10 F1 engines are treated as two inline 5s on a common crank for intake and exhaust tuning. With a 90 degree V and 72 degree crankpin spacing you can figure out the firing pulses and why they are treated as two engines.

 

Could you do that for each cylinder?

I don't mean to get too ideal, or theoretical...but...Could you just go ahead, and spend tons of money looking at different pistons and head and intake designs, etc. With each cylinder having its own throttle body(so that they act independent of eachother). And take all of those combinations, tune them all differently and come up with a plethora of various dyno graphs for this engine, with different combinations of parts, fueling tuning, etc.
Then divide you hp/tq graph by how many cylinders you have. That would give you the power per cylinder on your engine for every combination of parts. Then feed that into a computer program to determine your best total power curve by combining 10 graphs (one for each of the v10 cylinders). I'm guessing they already do this?