Joey Mack Posted July 15 Share Posted July 15 So I have been helping a buddy of mine with questions about his F-450. I have minimal knowledge on that engine. I know they are strong and are good work truck engines.. Well, he got it running good, better than when he bought it. He is 25 years old.. He wants to make a million HP, with it.. I said, just get it to run good, drive it as it is, and work it as it is.. He has a twin axle trailer and a bobcat and a small excavator. He has good skills as an operator.. anyway, He straight piped it anyway.. I told him to be careful, he could burn valves.. He's a Yahoo country boy and will have his 'foot' in at when he goes down the road.. I am trying to advise him to baffle the exhaust. He said to me today that his 'guy' is a diesel guy and brought his scanner to check the truck.. and has done a bunch of these.. So, this is where I have to step back and ask if I am wrong about my opinion on how to keep his 7.3 running for a long time.. 225,000 on it right now, with no knowledge of it's history.. I guess I am checking to see how dumb I am.. Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted July 15 Share Posted July 15 Only problem on straight pipes (other than noise) is if they are really short, and that really only applies to throttled engines. If a throttled engine is working hard climbing a hill then goes from wide open to fully closed, the vacuum can draw cool air back over the red hot exh valve. None of that applies to a diesel. As much as I despise straight pipes, I know of no damage it will do, other than to annoy everyone. 1 Quote Link to comment Share on other sites More sharing options...
BOBWhite Posted July 15 Share Posted July 15 (edited) The more smoke out the back the more soot in the oil and cylinder wall destruction. Sounds to me like it will last no longer than 250,00 before the motor starts using oil and looses compression. I know a lot of young guys just like that who try to make sports cars out of their diesel pickups. I get enough noise and smoke from my old farm equipment, I don't understand why anyone would want more of that. Edited July 15 by BOBWhite Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted July 15 Author Share Posted July 15 I was telling him about the ''Blow torch effect''. I dont want him to kill his new to him truck, Quote Link to comment Share on other sites More sharing options...
tjc transport Posted July 15 Share Posted July 15 my 88 ran straight pipes for 450,000 miles. the 02 ran straight pipes for close to 260,000 miles. both trucks were rode hard and put away wet every day. no muffler on a diesel actually makes it run better. Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
Joey Mack Posted July 15 Author Share Posted July 15 OK, well I will tell him that i was wrong with my concern's.. Thanks for the education.. Jojo Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted July 15 Author Share Posted July 15 so how do you guys feel about pyro temps at 1450 degrees.. I asked him what temps he is running in his '04 duramax, which is also straight piped,, to help me learn about these small diesels. I guess i am ashamed at how little I know about diesels.. Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted July 15 Share Posted July 15 Way too high, expect cracked pistons and head/valve problems. Smoke limit is around 1300 and aluminum melts a little over 1100. I saw 1500 a few times with turbo problems, and saw the results and they weren't good. 1450 is "rolling coal" and all the damage that brings. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted July 16 Author Share Posted July 16 Thanks GW,, My reaction wasnt good when he said 1450.. I figured I was right, but he looked at our boss man and they made some smug remark and smile at me.. I guess I will just stop trying to help and just wait for the story about engine issues.. I am a Yankee in the South .. Too funny,, Oh, where do I get good door mirror frames for MY KB-7? Quote Link to comment Share on other sites More sharing options...
fjh Posted July 16 Share Posted July 16 1 hour ago, BOBWhite said: The more smoke out the back the more soot in the oil and cylinder wall destruction. Sounds to me like it will last no longer than 250,00 before the motor starts using oil and looses compression. I know a lot of young guys just like that who try to make sports cars out of their diesel pickups. I get enough noise and smoke from my old farm equipment, I don't understand why anyone would want more of that. Amen ! That said a straight pipe ford sounds better to me tha the straight pipe dodge! I also hate harleys I like peace and quiet in my old age !😂 been married to long I guess! 😂 1 1 Quote Link to comment Share on other sites More sharing options...
mrsmackpaul Posted July 16 Share Posted July 16 6 minutes ago, Geoff Weeks said: Way too high, expect cracked pistons and head/valve problems. Smoke limit is around 1300 and aluminum melts a little over 1100. I saw 1500 a few times with turbo problems, and saw the results and they weren't good. 1450 is "rolling coal" and all the damage that brings. Exactly what Geoff said If the motor has no turbo you can burn valves, but theres plenty of back pressure with a turbo Pulling lots of black smoke for long periods washes the oil off the cylinder walls and shortens the motors life All that unburnt diesel does do a lot of damage, some times not very long time, other times quite quickly A good driver should be trying to minimize the smoke Motors also run a lot hotter when worked like this for a long period of time, ask any broad acre farmer from years gone by, having a glowing exhaust manifold on a farm tractor and a 12 inch flame out the exhaust makes them run really hot after half a hour Paul Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted July 16 Author Share Posted July 16 shouldnt the turbo have back pressure on it to keep it from spooling too high? his 7.3 does not have a CAC.. Quote Link to comment Share on other sites More sharing options...
mrsmackpaul Posted July 16 Share Posted July 16 I don't think so, I would think you would want the turbo to spool as quick as you can to get the correct air fuel ratio as quick as you can Paul Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted July 16 Share Posted July 16 I was pulling Bozeman grade after dark, fully loaded, when it sounded like I blew a tire, then the air kept coming, and I was looking at the air gauges trying to figure out what tank let go, then I saw the pyro! Ok I wasn't the quickest on the draw, but I had blown the crossover hose. Backed out as much as I could and made the top in the breakdown lane, coasted down the Livingston side and into the Yellowstone Truckstop. Next morning I bought a length of turbo hose and fitted it. Truck did fine back to Iowa and the next trip, but the trip after, it either cracked or holed a piston. I never opened it up afterword, and sold it, but always wondered what let go. Judging by the blow-by and the fact it came on all at once while pulling at speed, I think the piston cracked in 1/2 and punched a section out of the bowl. Got the load "re-powered" and drove the truck 250 miles home, took about 8 gallons of oil to make it! As to the bracket for the mirror, no I don't, I think Mr Chapin was making them, but don't know if he still is or how to contact him, try here: /www.chapindesignih.com 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted July 16 Author Share Posted July 16 Guess I need to hit the books. I thought turbo spooling and boost was congruent.. I guess i'm thinking wrong. I guess i wa thinking of making too uch boost and cause high chamber pressure and high heat for the head, pistons and valves.. Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted July 16 Share Posted July 16 7 minutes ago, Joey Mack said: shouldnt the turbo have back pressure on it to keep it from spooling too high? his 7.3 does not have a CAC.. No, "backpressure" is never needed or good, there is always some, but if the turbo is well matched and free-floating (no wastegate) it will speed up at altitude and try an make up the lost air, but that shouldn't cause a problem. Eventually it will reach a point where it can't make up the additional air and the diesel has to be de-rated, often about 7000 to 10,000 ft. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted July 16 Author Share Posted July 16 ok,, Thanks GW... I really have no knowledge of this and any other small diesels.. I just see so many youngin's trying to roll coal and spin tires and pull bigger loads than the truck is rated for, and I scatch my head.. I just need to stick to Macks,,, Quote Link to comment Share on other sites More sharing options...
mrsmackpaul Posted July 16 Share Posted July 16 22 minutes ago, Geoff Weeks said: Eventually it will reach a point where it can't make up the additional air and the diesel has to be de-rated, often about 7000 to 10,000 ft. Is this height above sea level I ask because I don't know, our mountains are not mountains by world standards Australia is very flat and we have huge (distance wise) pulls, but not big mountain ranges Maybe 20 or 30 miles of full power and drop a couple of full gears over that distance Maybe 50 miles would be the longest gentle climbs but pulling big weight at slower speeds All very interesting to me Paul 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted July 16 Author Share Posted July 16 7-900ft i guess ,,,, hell i dont know,, just a redneck 25 year old who wants to wave his diesel dick around,, i was just trying to help him from blowing the engine.. like I said... i dont know anything about this diesel engine.. Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted July 16 Share Posted July 16 35 minutes ago, Joey Mack said: Guess I need to hit the books. I thought turbo spooling and boost was congruent.. I guess i'm thinking wrong. I guess i wa thinking of making too uch boost and cause high chamber pressure and high heat for the head, pistons and valves.. I can recommend this book, Very dated by now, but an easy read and he covers lots of the theory in a way I could understand. 40 some odd years ago, I was working on Turboing a slant 6, got the math done and was building a manifold when life lead me in another direction. Had selected a turbo after learning how to read a turbo "map" from this book. Turbochargers - Hugh MacInnes, Betty MacInnes - Google Books 1 1 Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted July 16 Share Posted July 16 10 minutes ago, mrsmackpaul said: Is this height above sea level I ask because I don't know, our mountains are not mountains by world standards Australia is very flat and we have huge (distance wise) pulls, but not big mountain ranges Maybe 20 or 30 miles of full power and drop a couple of full gears over that distance Maybe 50 miles would be the longest gentle climbs but pulling big weight at slower speeds All very interesting to me Paul Yeah, I don't know the exact height, but it is why trucks can pull Loveland and Aspen passes and not loose much power. If you don't take the tunnel (or are prohibited) Loveland is just under 12,000 ft (11,900 something) 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted July 16 Author Share Posted July 16 thanksagain GW.. I bookmarked it.. its bedtime for me, but I will look at it thank you.. Quote Link to comment Share on other sites More sharing options...
The Heinz Posted July 16 Share Posted July 16 I've done some work on my buddy's 1996 7.3, and have researched more myself because of it. Straight piping it won't hurt unless he dumps it way too close to the engine, and I have to say that even though his was straight piped when he bought it, the engine is still louder than the exhaust! What will drastically reduce the engine's lifespan is any "tune," over-injectors, or whatever else the dipstick does to make it roll coal. I despise these kids with mommy/daddy money ruining diesels to make it blow smoke, it's asinine and ruins good engines. If he wants to make it at least somewhat capable of modern road speeds and acceleration standards, he needs to have a GOOD intercooler installed. No injectors needed, I wouldn't put a bigger turbo on it, just the intercooler. My friend's friend (also an acquaintance of mine lol) has a similar OBS 7.3, and has only had an intercooler installed as a performance mod. Gets good power, better fuel mileage actually, and the engine just runs better having a cooled turbo. If/when your buddy ruins his 7.3, as long as the truck's in good shape, I'd buy it for $100 and slap a 12 valve in it. Or install a Cat 3126 in it like DEBOSS garage on YT did lol. 2 Quote Link to comment Share on other sites More sharing options...
tjc transport Posted July 16 Share Posted July 16 they want to keep EGT below 1200 degrees. under 1100 is much better. with that said, i have seen 1500 a few times in my 02, but only for a second or two. i will not let my 88 7.3IDI go over 1100 degrees. even if the engine has no pipes at all, the manifolds will stay hot enough to heat any air that gets in before it does any damage to the valves. we bought an irrigation pump on the farm back in 72 or 73 with a desoto hemi in it. the exhaust manifolds were rotted out rite above one of the center cylinders on each side. we would put 10 gallons of gas in it and fire it up. then let it run until it ran out of gas. it had an oil pressure switch that turned off the ignition with no oil pressure. so to fire it up you held the ignition bypass until it showed oil pressure, than walk away from it. that pump has run over 50 years like that, and never burned a valve. the guy that bought it still runs it that way Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
Geoff Weeks Posted July 16 Share Posted July 16 Yes, irrigation pumps never "engine brake" where the engine is turned fast with the throttle closed. The only way it can happen is with a truck climbing a grade and then rapidly descending the other side with the throttle fully closed, and even then, it is unlikely and would require almost "open ports". I think the above truck situation is where the fable started, and was known in aircraft with no collector ring on the exhaust (manifold). Even aircraft, aren't likely to go from full throttle on and full off with the prop driving the engine. A lot has to depend on the cam and valve overlap when both intake and exhaust are off their seats and the manifold vacuum is very high. It is not a situation that happens in most applications. Quote Link to comment Share on other sites More sharing options...
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