scottyMIz Posted October 17, 2003 Share Posted October 17, 2003 hey guys was installing a radio in a new fire truck the other day and we had to open the hood to get our wires ran and i see this turbo on the truck(smaller than mine ) and i see that it has an internal wastegate which is weird on the big diesel engines i have seen.But anyway after the gate and a little ways down the dp there was a coller with i'm guessing is a flap hooked to an actuator like it chokes back the exhaust.Now rags and i where thinking he says maybe a brake and i'm thinking maybe something to help the turbo spool.Prolly both wrong but wanted your info on it. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted October 17, 2003 Share Posted October 17, 2003 That's the exhaust brake, which is also referred to as a 'Jake brake'. It uses the compression of the engine to slow down the truck. Tim Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted October 17, 2003 Author Share Posted October 17, 2003 thought they where someplace else? ok then joe was right i just haven't seen anything like that on any of the semi's i have ever worked on that's why i asked, thanks. Quote Link to comment Share on other sites More sharing options...
Chaparral2f Posted October 17, 2003 Share Posted October 17, 2003 Actually, it is an engine brake of sorts, but it isn't a Jake brake (Jacobson Copmpression brake). Its an exhaust brake. Basically, it just shuts off the exhaust. On the other hand, a Jake brake is a compression brake that holds the valves closed, effectivly turning the engine into an air compressor. The exhaust brake is quieter, it doesn't retard very much. The Jake is a much bettter system, but in comparison, it is really noisey. For what it's worth, IMO the best system is used by Catapillar, and is a hydraulic engine retard. It works like a large torque converter and its only drawback is that it weighs a lot. Joe Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted October 17, 2003 Share Posted October 17, 2003 Hmm....that sounds very simliar to an EXUP valve on a Yamaha R1....although, I don't know why you'd need it on a turbo diesel. Hmmm...now that I think about it...the Mitsubishi Evolution VII has a valve very similiar to that in the muffler...and it's a turbo... In effect, what it does (on the above to applications anyway) is to create more backpressure for low rpm/throttle operation, and then opens up to create a freer flowing exhaust at higher rpm/throttle operation... I wonder if it was something like that... Quote Link to comment Share on other sites More sharing options...
Bluto Posted October 17, 2003 Share Posted October 17, 2003 Without see'n it myself I woud say Chaparral2f nailed it right on the head.. Jake brakes are massive things built into/on top of the heads of the massive diesels, while exhaust brakes(which have become a really popular upgrade on heavy duty domestic diesel trucks, F550s 3500s etc that see alot of heavy towing) do about the same thing but can be installed on just about anything where theres a need. As for the wastegate.. unfortunately most all of the trucks I see at work from the fords and chevys up too big cummins and cats have internal style otherwise I would have a few of 'em in my tool box hah! The down pipe I replaced on a truck a few weeks ago (3 1/4") is goin to look real pretty on my turbo after I secton it just abit Sam Quote Link to comment Share on other sites More sharing options...
Guest turbo-max Posted October 18, 2003 Share Posted October 18, 2003 That's the exhaust brake' date=' which is also referred to as a 'Jake brake'. It uses the compression of the engine to slow down the truck.Tim[/quote'] it is a style of exhaust brake, but the typical "jake brake" hold the exhaust valve open Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted October 18, 2003 Share Posted October 18, 2003 ...I would think would use the exhaust to slow the engine down...wouldn't they put it before the turbo? Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted October 18, 2003 Author Share Posted October 18, 2003 see that is what i was thinking that's why i asked Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted October 18, 2003 Share Posted October 18, 2003 It still sounds more like what Mitsubishi and Yamaha has done...create an intentional exhaust blockage for off-boost response/power (or even noise pollution) and then remove the blockage under boost for more power... Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted October 18, 2003 Author Share Posted October 18, 2003 bill you and me are onthe same page Quote Link to comment Share on other sites More sharing options...
Moridin Posted October 19, 2003 Share Posted October 19, 2003 That's what it seems like to me. Keeps the exhaust velocity going off of boost for good respone (not backpressure ). I have heard about people dumping the blow off valve and/or waste gate (can't remember) back in front of the turbo to keep it spooled up. Quote Link to comment Share on other sites More sharing options...
Bluto Posted October 19, 2003 Share Posted October 19, 2003 ...I would think would use the exhaust to slow the engine down...wouldn't they put it before the turbo? The exhaust brakes are aftermarket things.. I dont think Detroit, Cummins or Cat has ever used one.. makin them all aplication specific to go befor the turbo would be nutty at best with the wide range of applications and cramped engine bays these things see. We need some pics.. ! tell the fire department that you have to do a uh.. umm.. radio check! hah Sam Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted October 19, 2003 Author Share Posted October 19, 2003 i'll try to get a pic dunno when i am going out that way again.Might be able to see another fire truck with the same thing. Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted October 19, 2003 Share Posted October 19, 2003 Most MAF equipped cars dump the BOV before the turbo to eliminate any richness during shifts...it's not really for keeping the turbo spooled. Quote Link to comment Share on other sites More sharing options...
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