guys and gals, i need some help here. a few years ago in one of my magazines i seen an article where a dude had a small block chevy that ran backwards (?) and used the exhaust ports for the carb intakes and the intake ports on the heads as the exhaust. told my buddy about it and he dont believe it. now i open my horse backstreet choppers mag and seen this bike doint the same thing, the exhaust is the intake and the intake ports are the exhaust. 2nd picture down http://www.stevensonscycle.com/inde...t=show&albumid=48&photoid=5376154154960091714 can someone please explain how this is done, and are there any advantages to running it this way. what about costs ? i think its the coolest thing. dont see this every day. thanks in advance. leonard
Primarily, it takes a camshaft that is ground ("timed") for this use. I'll leave it to others to tout the advantages. Ray
Just to be different! Valve sizes end up wrong for starters. Plumbing the intake becomes too complicated.
You're talking about two different things here. Backwards running engines actually turn the crank in the opposite direction, from typical rotation for a specific engine. Backwards BREATHING engines can still have crank rotation the "normal" direction, they just breathe in through the "exhaust" ports, and blow the hot waste out the "intake". The photo of the bike you referred to is a reverse breathing, normal rotation engine. In either case, it's accomplished with the cam profile.
I remember yrs ago a guy had a Flatty that was set up with 6 Carb at the exhaust ports and exhaust out the top, I believe he was a the Salt Flats, and the run was a problem as it stuck in low, and he said O WELL and ran it. If memory serves me he clocked 101. 2nd run was OK and ran 110 in high, believe it was in an old Hot Rod Mag artical. Iceman
Ford's new diesel has the intake on the outer part of heads, exaust and turbo in the valley of the V/8.
Imho, and I am by no stretch an expert on flathead engines is that people did this the RIGHT way, way back then to get away from the exhaust ports going the long way through the water jackets to exit the block. This did away with a lot of known hopped up flathead engine cooling problems, again, imho. pdq67
Backwards running engines are actually pretty common...WAY O/T here, but my current snowmobile (2009 MXZ 800R) can run in reverse. In fact, when I want to back up with it, when the reverse button is depressed, the engines electronic timing gets retarded 180*, and almost stalls, then fires right up backards.
Two stroke engines can run backwards easily. In my wayward past I rode a lot of off road motorcycles and an old Bultaco Matador I had would almost stall going up a steep climb and if you pulled in the clutch at the right moment, it would fire and run backwards. Big suprise when you revved it up and let the clutch out.
True, most guys who reversed the intake/exhaust did it to get better intake flow, John Bradley did it to his flathead once, carbs on the side and headers out the top....there were also a couple of Buicks ... one on Don Ewald's "from the beginning" pages, front-mounted blower with intakes running to the former exhaust port and headers off the former intake ports.....cams obviously had to be reconfigured.......since not a lot of guys did it, my expectation is that it was not worth the extra work.
I read an article about Smokey Yunick ran his 308 Hudson backwards and flipped the rearend over so the engine would torque to the left for circle track racing This was in HOT ROD magazine years ago
they aren't running backwards.....just because the intake and exhaust are swapped doesn't mean the are turning in a reverse rotation.
thats exactly what i was talking about. not the actualy one i seen in the mag, but the same concept. thanks for the explanation on how its done, with a special cam. cool but looks expensive to convert. leonard
OK guys here we go again. this has come up several times before and IMHO aleays was a dumb idea with the exception of the Ron Main/Dick Landy flathead. But anyway lets think about how a cam works. After the power stroke the exhaust opens and as the piston comes up as the exhause closes the intake opens and the cycle begines again. If you reverse the rotation of the cam in relation to the crankshaft in effect the cycle is reversed and the intake and exhaust events become backwards. Now your intake valves have become exhaust valves and your exhaust has become intake. Now you need new manifolds to accept this and using intake valves for exhaust insures a trip to the valve grinder in the near future. But it is not a special cam. It's a special cam drive. switch your chain for gear or the other way around. But it's still only for the "Look At ME" crowd
LOL, I'm glad I don't like attention. I had a Merc Mark 75 "Dockbuster", an inline 6 2 cycle, that had no reverse gear (or nuetral). To reverse the engine, you shut it down, pull the shift lever back, hit the key, and if goes well and you held your face just right, it'd fire up and run backwards. Evidently, commonly thru docks, hence the nickname...
Same as one of these. Mercury Direct Reversing, Direct Drive, 6 cylinder outboard. I've restored a few.
Ill bet you could package a pretty cool turbo set up on a sbc like that. All 8 coming out the top driving twin turbos to feed the (now) exhaust ports with port fuel injection. I know the idea isn't traditional hot rodding but the turbo would probably make up for the small ex valve size and the old intake valves could really breathe. If I win the lottery I'll build one and stick it in a 55 ford truck!! Obviously I know nothing worthwhile about this subject.
Here we are confusing running an engine counter clock wise instead of clock wise. Easy to do on some two strokes. But this thread is about swapping the intake and exhaust ports and still running the engine in the conventional rotation
That sbc is using the small exhaust valves for intake, and the larger intake valves for the exhaust, so its breathing will be far from ideal. However, the Harley in the OP's link has the front head swapped with the rear head, so it should flow as well as a normal Harley (except for the funky intake it uses). But still, no advantage other than the wow factor. wow.
Note the exhaust is not discolored and the firing order from the arrangement visible ain't gonna work. 5 stars for the distributor thinking tho!! Has this ever run? When it does, drivability will not be much different from normal (up to 4000 rpm or so) The Hudson story is correct...........jump on the gas and the torque loads the chassis to the left.........perfect for TURNING left. All those who have broken that left hand engine mount know that the regular motor is trying to turn right. The piston goes up and down just the same forward or reverse so if the cam lobes are tweaked the intake valve is still the intake valve. Check the plug wires for firing order, flip the starter (Smokey prolly push-started his).........drive away.......backwards.
P-38 Lighting had counter rotating engines to offset torque.Different cam and starter to make it happen.
i talked with this guy, real nice. he said it runs on ethenal. also he said he ddnt do anything with the vfalves(in case your wondering)
The licence plate would indicate reverse flow through the head, NOT reverse rotation of the crankshaft. Looks like the Chevy is running a "two gear" cam drive in place of the chain-and-sprocket stock drive. The distributor cap is internally indexed for the 1-8-4-3-6-5-7-2 so that the even numbers neatly supply the 2-4-6-8 side of the engine and the odd numbers supply the 1-3-5-7 side of the engine! Rich Fox had it right. This stuff has been thrashed around before. Do a search.
If it would make more power and tork it would be worth the trouble. But as far as I can tell its a wast of time in my book.
I know that. He said "backwards running". I just thought the notion of the backwards running inline six, with direct drive, was interesting, as was the moniker "dock buster" and the scars on that little boats hull from intimate contact with docks. Sorry it bugs you. I've had cars that would "diesel" a while on shut down and run backwards doing that. There, another wander away from the intent of the thread... Brian