Detroit Diesel Differences?

[spicergear]

One thing to keep in mind on the 2 stroke Detroits is that the 'supercharger' really was just on there so the engine could run. The blower is part of the scavenging system which makes them two stroke. There is no special hot rodding effect it is just an absolute necessity...like our lungs.

 

[Alredneck]

One thing to keep in mind on the 2 stroke Detroits is that the 'supercharger' really was just on there so the engine could run. The blower is part of the scavenging system which makes them two stroke. There is no special hot rodding effect it is just an absolute necessity...like our lungs.

THat why we put big and multiple turbos on them! HEHEHE!

 

[paradeduty]

True - according to the design basics of the 2-stroke Detroit, I think the blower basically helped "clear" the spent fuel mixture and possibly introduce the fresh mix for the next cycle. I think as the piston is pushed down during the burning of the fuel, the down-traveling piston exposes the exhaust ports (as opposed to valves opening) and the blower "pushes" out the expended fuel as it introduces new fuel. Please let me know if my interpretation is correct. Dave.

 

[paradeduty]

If this is correct, it really is a simple system. Kind of similar to a rotary engine where the rotating "piston(s)" essentially sequentially "pass by" the respective intake and exhaust "ports" in a precise fashion. Pretty neat - no valves at all if I remember correctly. Dave.

 

[fcdrifter13]

No valves at all and a very cool noise. That and they last forever if they are not turbo charged. I've owned just a couple of them little buggers.

 

[paradeduty]

Honestly, never had the chance to purposely listen to one (have probably been around a few without knowing it!) - they did not like the turbos? The original design had too close tollerances for "extra's"? Man - get one of these with a turbo or worse (better?) toys and they must have really wound up!!

 

[fcdrifter13]

No they love boost tell it go es a tad to lean or gets a bit hot. One of two thongs will happen, if it pings just once 95% chance that it'll toss a corner or apex seal, and if they overheat they eat coolant seals which is just a piece of rubber ring basically.

I love the cars to death as the second gen. Chassis code has been my screen name since 01 for every forum im on, I just wouldn't own one right now. Ill stick to my old 71 Datsun z and the twin turbo 300zxcharged im trying to sell.

 

[spicergear]

I've rebuilt upwards of 20 rotary engines in configuration from stock to ceramic apex seals in nitrous fed drag engines. The standard two rotor design for comparison sake would be like a 6 cylinder two stroke engine. Not much for torque because the rotating mass is light in comparison but rpm and hp...wow, then really go. The sound is somewhat of an acquired taste. Right off the bat you may think its an outboard engine running inside a 55 gallon drum but once you get an ear for it...it becomes a little more of 'music.'

Detroits 2 strokes only have exhaust valves. The intake is ported though the cylinder. From the experts on the marine side of the uses for these engines...they were good and durable to about 1hp per cube. Once you got above that you were looking to freshen up the engine about every other year. It was pretty common to see a pair of these with a pair of turbos each shoving pleasure yachts through the waves back in the day.

 

[paradeduty]

woops! had the intake and exhaust "valves/ports" backwards - thanks for the education! Kind of makes sense if I were to have thought about it a little more - pretty difficult to make jake exhaust brakes (common I believe on these for OTR) work without valves instead of ports (especially the variable Jakes, I would guess).

 

[promodhotrod]

I would suggest a 6-71 for your 5-ton. Its very easy to power a 238 to 300, and your cooling system may be adequare. I can say it will be way small for an 8v92 if you want to use the right pedal

 

[OPCOM]

rotaries - I had a job installing cruise controls in RX-7's which were then sent to be souped up. The cruise control had to be able to handle what the speedo said so as part of the test each one of those spent a few seconds at 120MPH on the highway. Less traffic and cops then for sure.

 

[Mike929]

Just purchased a 8v92 for a future project and my brother wants to build a stand and see if it starts and runs. I have the starter but there isn't a gear ring for it to engage.

Does one of the Detroit guru's know the part/part number I am missing? Also I was curious what the best automatic transmission would be for this engine in a future project. (best meaning something I can afford that would be well suited for the 8v92 )

RE Future project
We wanted to make sure we had a good motor, then find a trans and then find a truck to wedge it into. This would probably be a highly modified deuce if we can find the room.

Thanks for any help.

 

[spicergear]

Lots of Allisons reside behind the Detroits...

I had once set an 8V71T up on a stand to run. Batteries, small 12V fuel pump as lift pump pumping fuel to mechanical pump on front of blower. Make sure you don't just have a threaded hole into the head at the fuel outlet. There is a special fitting there to keep upwards of 50psi or 60psi or so (can't remember exactly...) in the internal fuel rail. If that fitting is gone you won't make the fuel pressure and it won't run. Also something you can...and prolly should check if you don't know the running history of the engine is to pull the head pans and turn the engine over and watch each injector's rocker arm push down on the injector/plunger. You may find one or two that push down and stick or are stuck down. That injector needs to come out to be torn down and cleaned. I had four, two on each bank, on the 8V71T and it wouldn't fire on four good ones. Pulled, tore down, cleaned reassembled, ran good.

 

[Mike929]

Thanks for the info. Is there a TM on these engines? I believe the 8V92 is out of the HEMTT, but not positive.

 

[spicergear]

I think they're 445hp 8V92's in the HEMTT's.

 

[Stalwart]

Spicergear is correct about the DD in the HEMTT's. I'm thinking about bigger injectors for mine . . . perhaps even a new engine with them installed before transplant.

 

[raeme]

Put a Detroit in. And I sent Patracy a full parts cataloge for all DD engines to put up on the site for you boys to use.
raeme.

 

[spicergear]

Just wanted to say that I would put about 10 'THANKS' under this post if I could.