banshee04le Posted January 8, 2004 Report Share Posted January 8, 2004 hmmm well if you are talking about like a butterfly valve since it pivots in the middle one side is being pulled down to open it but the other side is pulled down to close it so it equals out? thats the only thing i can think of oh yeah....duh thanks! Quote Link to comment Share on other sites More sharing options...
MILO Posted January 8, 2004 Report Share Posted January 8, 2004 does a two stroke have engine braking like a four stroke? Like when your on a four stroke and your coasting down a hill and start going to fast and you down shift to make it slow down. after reading all of these in depth responses, here's my opinion. uhhhhhh, no! i mean, yeah! well then again, maybe not. did yu sa u want to break yer ingin?? just kidding. engine braking-yes, but you won't notice it near as much as you would on some 4 strokes. Quote Link to comment Share on other sites More sharing options...
Travis's Banshee Posted January 8, 2004 Report Share Posted January 8, 2004 I guess I'll jump back in here. I to have done the test also. See a previous post of mine. For the vehicles used. W/a loaded enclosed traler behind, the diesel stops 40-50 shorter. Can't explain it. It just does. both are equipped the same. Quote Link to comment Share on other sites More sharing options...
boonman Posted January 8, 2004 Report Share Posted January 8, 2004 I guess I'll jump back in here. I to have done the test also. See a previous post of mine. For the vehicles used. W/a loaded enclosed traler behind, the diesel stops 40-50 shorter. Can't explain it. It just does. both are equipped the same. I don't know how that is possible Trav. I am not doubting you, I do however know that my findings are the exact opposite. Oddly enough. I have always found that diesels "freewheel" down the road a little longer than a gas engine... Vehicles I used were a '98 Chevy 454 truck, and a '01 Duramax. The diesel freewheeled and I had to use more foot brake to keep speed in check. So, I researched it. I have also been involved in pulling, and diesels for quite awhile. I do know a thing or two about them. Newer diesels are getting wayyyyyy better than compared to the older stuff for engine braking... Quote Link to comment Share on other sites More sharing options...
boonman Posted January 8, 2004 Report Share Posted January 8, 2004 i know little about diesels but my friend owns a big garage for them and i have walked around plenty of times to see engines all apart 1/4, 1/2 and full together. i am pretty interested in them so im going to respond to this. if a diesel has valves for the intake, then what does it matter how much unrestricted air is behind that valve? i am on no ones side just trying to learn myself It matters because a diesel will suck in as much air as it wants to according to it's RPM. Nothing combusts, because there is little to no fuel being sent in. So, it is just sent out the exhaust. WHile this compressed air will slow the engine some, it is different than a gas engine. My point exactally! Same thing in a gas engine You see, it is not the same thing. A diesel engine, when left STOCK, will brake itself on compression. Whereas a gasoline engine brakes itself on vacuum. Look at it this way, on intake stroke, a diesel will suck in the copius amount of air. Then compress it. no biggie. That will slow the motor. I didn't say that it wouldn't. On a gasoline fed motor, the intake valve opens, and the cylinder tries to draw in air. Well, there is no air to draw in, because there is no air being let in. So, it is essentially vacuum braked. Diesels don't create vacuum. I just don't feel that diesels engine brake as effectively as a gas engine. With the right equipment however, it will outperform it three fold. Quote Link to comment Share on other sites More sharing options...
fixitrod Posted January 8, 2004 Report Share Posted January 8, 2004 I told you boonman Quote Link to comment Share on other sites More sharing options...
Travis's Banshee Posted January 8, 2004 Report Share Posted January 8, 2004 Hey Boonman. Just a thought here. When I did my test, it was with manual trans in both. Not sure how yours were setup. I do now one of the guys I work with has a '03 powerstroke w/an automatic. The trans seems to let it feewheel more. Not sure if this is due to the torque converter or what. Quote Link to comment Share on other sites More sharing options...
H300F Posted January 8, 2004 Report Share Posted January 8, 2004 wow makes a lot of sense now. i was looking at it totally wrong and believing the compression in the cylinder is what caused this. what other shit is there to learn about diesels haha? is their stroke a lot bigger then bore etc?? is it easy to blow a rod or spin a bearing if overrevved like some bigblock gas engines? what i found insteresting was the amount of oil one i looked at took, 34 quarts. Quote Link to comment Share on other sites More sharing options...
boonman Posted January 8, 2004 Report Share Posted January 8, 2004 There is one way to overrev a modern diesel. You can hold your foot to the floor, and it won't go past redline. That is stock. Go look at a powerstroke, and fire it up. Hold your foot to the floor. I bet you anything you want that it won't go past redline. Now, if you are running down a hill, it may be possible to overrev it. And there is danger. The rotating mass in a diesel is HUGE. Everything is very heavy. it has to be in order to withstand the pressure involved in it's combustion. You can damage a diesel engine, although it is alot harder to do. Travis, this was with standard trannys as well. In Chevy;s tow/haul mode, when you let off the gas, it will keep the torque convertor locked to aid in engine braking. That's what it's there for. it will also downshift the tranny for you. Whereas others will not. You can make them do this. There are transmission controllers available aftermarket that will do this for you. With an auto tranny, it is necessary to lock the convertor to do this. Also, to not build heat, you must lock the convertor. I have also tried this test with Automatic trannys with manual lockup control. it was the same result. I tow alot of things. And I have always found that a gas motor would stop the load without brakes a little better than a diesel could. Stock for stock. Now, not stock is a different ball game. Put an exhaust brake on a diesel, and you will likely never change brakes again..... Quote Link to comment Share on other sites More sharing options...
got1banshee Posted January 8, 2004 Report Share Posted January 8, 2004 Hey boonman, I pull a traiter all day every bad and I have a Powerstroke. How do I install an exust brake and where do I get such a thing? That would be handy as hell. Pm me if you can. Thanks Quote Link to comment Share on other sites More sharing options...
BansheeJerry Posted January 8, 2004 Report Share Posted January 8, 2004 Boonman, Alot of vehicles have plastic-composite intakes. They have been on engines for years. I guess you dont keep up with the automotive world... GMs LS1, fords 4.2 and VW VR6 are just a few examples. There are many more... Quote Link to comment Share on other sites More sharing options...
boonman Posted January 8, 2004 Report Share Posted January 8, 2004 Well, composite!!! Not a full on plastic intake. (That's what I wasa thinking of) Sorry about that. I was making some nylon shit this morning in the shop and I guess I just had plastic on the brain??? And a hard night of drinking will do that to ya sometimes... Quote Link to comment Share on other sites More sharing options...
p8121 Posted January 9, 2004 Report Share Posted January 9, 2004 Ok, first off your right you dont deserve to be sworn at. I'm sorry for my foul language. Secondly your still wrong, and I cant even to begin to scratch the surface in the aeras where you are worng. The reason I wrote "from what I understand" is because this is how I understand it to work. UNLIKE YOU I dont go shooting my mouth off acting like I am an expert because I know there is a chance that I may be wrong. I keep an open mind, you should try this. If you had I wouldn't have been so harsh on you. I cannot stand Iragont people like yourself who think they know everything, then prove to you that they don't. You on the other hand claim that you "know" how engine breaking works, however your theory is wrong. You said that a diesel engine has little engine breaking because it has an unrestricted intake, thats why I thought you understood engine breaking to have something to do with the intake. So thats where I was going with that whole blowing vacuume lines off thing. think about it if your compressing the air from the engine back through the intake, would't that happen? What vehicle has a plastic intake?? holey crist for someone who is such an "expert in engines you should be able to rattle a few dozzen.. Since I know nothing, heres a few that have plastic intakes My 2003 F150 5.4L has one, so does my 1998 Ford Crown Vic 4.6L. Ever open the hood of a Taurus they all have plastic intakes. How about a windstar, freestar, ranger, mustang and a Focus, they all have plastic intakes. You never heard of any of these cars? Oh thats right you only speek on factual knolwedge right? So you MUST not have ever head of any of these cars. DAMM YOUR SOME KIND OF AN EXPERT ALLRIGHT. *side note. I work at a ford dealer and rarly see under the hoods of other vehicles but I believe the dodge neon has a plastic intake (I had a friend who had one) ok heres another good one from boonman "With your theories, these vehicles should stop on a dime every time you let off the go pedal" Yeah thats what my theory proves... right. At which point did I say engine breaking will stop you on a dime? But to answer your question, YES engine breaking does occour when you let your foot off the gas. you normally dont feel it because you probably have an automatic transmission. DO THIS put the trans in 1 (thats past Drive and 2) take off, get going to like 20-25mph....let off the gas, what happens? HOLEY SHIT ENGINE BREAKING. You can do this in a manual transmission too. Perhaps you dont know what the 4 strokes in a 4 stroke engine are. 1Intake (sucks in air from the intake, which also creates vacuume in the intake) 2Comresson (this is what your running aginst in engine breaking) 3Combustion (when the air/gas mixture explode sending the piston down) 4Exaust (exaust valve opens and the piston traveline up pushes the gas out) Take away fuel and air (so there is less combustion) and push the engine (from the driveline) and what do you get...engine breaking So during the compression stroke how in the hell is air going to be pushed back into the intake? Lets see....with both valves closed, it wouldn't. SO WTF DOES THE INTAKE DESIGN HAVE TO DO WITH ENGINE BREAKING????? NOTHING YOU IRROGANT JACKASS!!! Just to clairify I do not dissagree the fact that diesels have unrestricted intake air flow. my point is that the Intake side of the enigne has little if anything to do with enigne breaking. Which makes perfect sence, since the intake is only exposed to the volume inside the cylinder during the intake stroke and at that time the exaust valce is closed and the pistion is traveling DOWN. It just baffels me that you dont understand this. How can I deny that your bs is BS? because it is, retard. by the way what sort of mechanical background do you have? just wondering where you get your "factual information" from. Quote Link to comment Share on other sites More sharing options...
rebelbanshee2 Posted January 9, 2004 Report Share Posted January 9, 2004 air isnt being forced into the intake. the piston is trying to suck through the intake but it has nothing to suck cuz the throttle is closed off, maybe your mind was too open and that went right through this has been one of the most intersting and amusing posts ever Quote Link to comment Share on other sites More sharing options...
banshee04le Posted January 9, 2004 Report Share Posted January 9, 2004 vacuum lines blowing off, huh? in boonies defense, it should be remembered that diesel engine applications that require vacuum (whether it be a brake booster on a vehicle or whatever) use a seperate belt driven vaccum pump to supply this vacuum. why? because a diesel engines intake vacuum is very low. why? becuase the air intake is unrestricted. so there you go. and your dumb, dude. he didnt say anything about compressing back against the intake. he said that the closed throttle plate represents a restriction on the intake...nothing to do with compression...so therefore, no restriction on the intake=less engine braking on a diesel. it "just baffles me" that you don't understand that restriction on the intake represents a slowing effect on the engine, thus engine braking. and we all know the valves are closed during compression, so maybe you should just go eat another PB and jelly sandwich you fat b@st@rd. oh, yeah...and the word is arrogant. you need to learn to spell too. and its spelled baffles...not baffels. i could probably find more examples but i am too tired to look after reading your long ass bullshit post. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.