Guest iskone Posted August 4, 2004 Share Posted August 4, 2004 I just read on another forum that you can grind a cam in "reverse" so that the engine spins the other direction. Here is the qoute. "A cam swap is usually a very straightforward and simple undertaking, and for non-"balance shaft" engines, doesn't it seem that all you'd need to do is get a "reverse rotation" grind (such as is common in marine cams)? Any competent cam grinder should be able to fix you right up with the proper cam to make your engine "rotate backwards" Any thoughts? Isaac Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 4, 2004 Share Posted August 4, 2004 Lots of ships will back out of a docking slip by turning the engine backwards. I'm not really too sure of much more than that, but I would guess it might be a way of getting the ship to back up without having to have a gigantic transmission attached to the engine. Not sure if the engine just connects directly to the propeller or if there is something else in there on most ships. If you were to do that on a car engine you'd also need to reverse the distributor, so I would think this is something that works better on mechanically injected diesels. EDIT--I suppose you'd also have to do something to get the coolant flowing since the water pump wouldn't work right. Also in a car you'd have a 5 speed in reverse and 1 forward speed, or whatever your trans was backwards, unless you swapped in a Saab trans (I think they spin backwards) Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted August 4, 2004 Share Posted August 4, 2004 A remote electric water pump would fix cooling. Do you think that there would be trouble with the altanator, I don't. From what the tec at Comp Cams told me is Marine guys often use 2 engines ans if they spun in the same direction it would flip the boat. I don't know if they would flip, but that's what he said. Trans spinning is why I asked in the first place, I want the rotation to do just that. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted August 4, 2004 Share Posted August 4, 2004 I used one in my very first engine swap, a Corvair engine in a VW Bug. For automotive engines, the Corvair and 4-cyl Hondas are the only ones I can think of that would need it and only if doing an engine swap. Nothing to it except you have to remember the firing order. Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted August 4, 2004 Share Posted August 4, 2004 You used a reverse grind cam? That was somthing I was thinking about, firing order when I tell the grinder to grind the cam couldn't I tell him I want to keep the stock firing order. Or would I need to have the HEI custom made? Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted August 5, 2004 Share Posted August 5, 2004 Just an electric water pump that was designed for a serpatine belt would work. Quote Link to comment Share on other sites More sharing options...
SpeedRacer Posted August 5, 2004 Share Posted August 5, 2004 Most boats with twin inboard engines have one that rotates counter-clockwise and the other in a clockwise (opposite) direction. If both engines rotated in the same direction the boat would always want to turn in the direction the screws (propellers) are turning. By using counter rotating engines you cancel out the torque (thrust) and the boat will go straight (when the engines are turning at the same RPM). That being said, I don’t know why you would want to use a counter rotating engine in a car. Quote Link to comment Share on other sites More sharing options...
660Z Posted August 5, 2004 Share Posted August 5, 2004 boats that have two engines ...one runs in reverse rotation. Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted August 5, 2004 Share Posted August 5, 2004 I did some reading about reverse rotating engines in boat use, I didn't think they would flip. MSD and all the rest make a Marine HEI All that is left is and oiling system and a strater. Why wouldn't I want an engine that spins in reverse!? Wish me luck! Quote Link to comment Share on other sites More sharing options...
Peternell Posted August 5, 2004 Share Posted August 5, 2004 Please don't "think me dumb" for asking but would not reverse rotation cause the drivetrain to also spin backwards yielding anywhere from 2 (powerglide) to 6 (T56) reverse gears and 1 (previously reverse) forward. I've torn apart a 327 Chevy in an old CrisCraft that had reverse rotation complete with a direct drivet gear to the cam. Cam and distrubutor spun normal just the rotating assemble went backwards. Not an issue since it was mated to a Paragon Drive. I'm more curious as why this is of interest. Just to be different (way different) or am I missing the little known key to HP and TQ? Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted August 5, 2004 Share Posted August 5, 2004 Smokey Yunick did just what you said. Said he was racing at some track where the normal engine rotation torqued the car to the wrong side (can't remember if it was the inboard or outboard side). Said he ground the cam backward, flipped the rear diff upside down (if I remember right) and used engine torque to help balance the car. Said he never got caught. Same book said they once changed the rules limiting gas tank size. He got so pissed, that he ran enough fuel line to hold an extra 5 gallons. Racing secrets of the pros! And yes, multi engine boats as well as airplanes use counter rotating screws/props to prevent the "paddle wheel" effect from constantly trying to turn the craft. Most ships have variable pitch screws that allow the ship to go backwards simply by reversing the pitch. Didn't someone on here once say that diesels can run just as well backwards as forwards? Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted August 5, 2004 Share Posted August 5, 2004 Why wouldn't I want an engine that spins in reverse!? As mentioned earlier, four out of five reverse gears would be useless. Even if you wanted to go 60mph in reverse (I know, I know) you would prematurely wear out your tranny and rearend driving the backside of the gears. On the Corvair note: I know a guy that was working on a V6 swap into a Corvair and he was using a reverse rotation marine engine. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 5, 2004 Share Posted August 5, 2004 As mentioned earlier, four out of five reverse gears would be useless. Even if you wanted to go 60mph in reverse (I know, I know) you would prematurely wear out your tranny and rearend driving the backside of the gears. That is a good point. But, if you got a tranny designed for it there are a number of 4x4 front diffs that are built for reverse rotation, probably the easiest to make work would be a Ford 9" housing with an 8.8 reverse rotation 3rd member since custom housings are easy to come by. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted August 5, 2004 Share Posted August 5, 2004 I have heard of snow machines that run backwards in order to reverse.. (less weight, as a reverse gear/drive system isnt needed) The engine will atually stop, and restart in the other direction! Basically, it makes it 'diesel' ..run off the heat of compresion rather than spark I supose.. or something.. As for 'reverse grinding' a cam... why? Could you not just get a marine cam and ignition for the engine you're wanting to use? Ive heard of ppl usin a 'marine' block to build a motor for their street car so Im sure it'd work the other way too... Quote Link to comment Share on other sites More sharing options...
80LS1T Posted August 5, 2004 Share Posted August 5, 2004 Correct me if I am wrong but the only reason you would have 5 reverse gears is if you dont turn your differental around. Essentially you are just turning the input shaft the other way which is turn the driver shaft the other way which is turning your diff in reverse. I dont think it matters which way the inputshaft spins just as long as your diff is turned in the right direction. Guy Quote Link to comment Share on other sites More sharing options...
spdsk8r Posted August 5, 2004 Share Posted August 5, 2004 Many of the dirt sprint cars are running a reverse rotation engine. Because these cars are so small and have so much torque the counter rotating engine negates the tendency of the engine torque to try to flip the car on the tight turns. I can see the advantage if you were racing on a short oval track. Quote Link to comment Share on other sites More sharing options...
Guest Aaron Posted August 5, 2004 Share Posted August 5, 2004 I discussed this once with a buddy that was considering it for his dad's dirt track car. He never did it though. I have read that reverse rotation engines do not make the same power as a std engine with the same specs. Presumably because all the components are optimized for the airflow of a forward rotation engine. If you flip your differential, that corrects the problem of multiple reverse gears and one forward gear, but I have also read that some rear ends have lubrication problems when upside down. Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted August 5, 2004 Share Posted August 5, 2004 I've been doing alot of reading and making alot of callls. Golen will build me a reverse rotation small block for a couple hundred etra bucks. Grind the cam in reverse, they will put a different dis. gear and seal on it thus reversing the oil pump and a new front and rear main seal plus reverse rotation starter. I've seen some marine blocks make less power but they are not standard parts to begin with. Now, why do I want a reverse rotation motor. Well, before I got into Z's I was into Porsche's and wanted to build a 914 mid-engine with a small block chevy. Problem is (1 of many) that in order to use a stronger transmission you have to have the ring gear flipped and the case machined. But I was thinking if I just reversed the rotation of the block there would be no need to have the ring gear flipped. If you don't flip the ring gear you get 5 reverse gears and 1 foward. Of course I need to do more research but I think I've got most of it solved the guys at golen said the water pump would'nt be an issue but I'm not too sure about that. Isaac Quote Link to comment Share on other sites More sharing options...
BillZ260 Posted August 5, 2004 Share Posted August 5, 2004 Correct me if I am wrong but the only reason you would have 5 reverse gears is if you dont turn your differental around. Essentially you are just turning the input shaft the other way which is turn the driver shaft the other way which is turning your diff in reverse. I dont think it matters which way the inputshaft spins just as long as your diff is turned in the right direction. That is true but... As mentioned earlier, four out of five reverse gears would be useless. Even if you wanted to go 60mph in reverse (I know, I know) you would prematurely wear out your tranny and rearend driving the backside of the gears. This is also true unless you have a transmission with ALL straight cut gears. I know there are some out there but aren't mose helical cut? I know the diff is, so you are putting the power to the side of the gears not meant to take a load. Seems to me if you got on it hard that you would start snaping cogs or slipping across them... Quote Link to comment Share on other sites More sharing options...
SpeedRacer Posted August 5, 2004 Share Posted August 5, 2004 Isaac, There is a kit available to convert the engine in a Porsche 914 to a small block Chevy (SBC). Since the 914 is a mid engine car you do not have to change anything in the drive train. An adapter is used to mate the SBC up to the transaxle and a custom clutch is used. Since the Porsche engine and the Chevy rotate in the same direction it is not a problem. Quote Link to comment Share on other sites More sharing options...
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