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Discussion in 'Chevy' started by cheapracer, Sep 2, 2017.
This will fit in around here somewhere ...
Yes, they have been installing Chevy LS Series V8's for a long time. Chain drive PSRU, however.
But...this is interesting. A GM ECU?
Engine Control System
The Computer I chose is a standard G.M. system. The unit is Custom programmed with the export code for leaded fuel, and uses no oxygen sensors. This was to enable me to run 100 octane Low Lead fuel as well as premium unleaded fuel. The emission and VAT codes are suppressed. The wiring harness was purchased from an after market supplier. Computer Power is supplied from one of two full size batteries. The batteries can be manually isolated in case of an alternator or battery failure. The computer power source is selected manually.
I bet Ross will not like this! Then again, maybe so.
Is that a problem? Do they have issues?
Not sure. I just feel better with a geared drive PSRU.
There is at least a half dozen GM aftermarket engine management companies. Not many will help with aviation. You do them all the same, though.
As most of you now know, we are using the Link G-4+ Extreme ECU. This is now the ECU of choice for our application.
An engine builder tried to get us to use the Delphi ECU, claiming it was just as good. I knew better!
With custom you want programability. The quality of the Delphi and advanced guts is hard to beat, but beating the built in OBDII garbage and their new sneaky stuff is the tough part. Custom electronics have come a long way since a friend of mine was developing the modules for Hypertec in the 80s. Rip it up on the computer and have the boards printed for just about $30, solder parts and go. It is harder than that, but just as easy as that if you know what you are doing.
I've talked to 3 customers of their's and it isn't all roses. They have had piston failures and engine stoppages. The guess is they don't have all the re-calibration and tricking out sensors properly managed. They were attempting to run closed loop at higher power settings than OEM to get the fuel consumption down in cruise. This led to piston failure on at least one conversion far from home. Another I talked to had the engine shut off completely (luckily over a lake) and he put it down safely. He was looking at SDS or a Lycoming. Haven't heard back yet.
He would be money ahead going with SDS.
Not my area, I can say that Delphi appear simple and run millions of engines out there.
Makes it very simple for 'crate engines' in China as the Delphi is a separate specific ecu on many engines. I think ... :nervous:
I understand that, but if they have been "around for a long time" and no distinct problems with the PSRU, then it must be reasoned that they are working ok?
Only if you make the assumption that they actually have sales, and that the sold items are being used.
There's a number of Seebees converted and that's what drew me to the site. I am not aware of what others use their products, but the Seebee guys seem to have had a decent run.
The FAA did ground a V8 SeaBee this year. I don't know if it was a clone or one hiding as a EAB, but I know my FSDO would not sign any of that paperwork today and supposedly is about to get worse with them getting rid of the local offices and going to regional offices with many inspectors working out of home.
Robinson has only sold a handful of these conversions over many years to my knowledge- I believe something around one per year. A couple have many hundreds of hours but considering the small number flying and the problems that I've heard of from some owners, I'm not so sure they can be called a big success.
Problems with their ECU setup or the drive unit itself?
That is my question.
Where is the actual problem...
3. LS V8
One of the above? All of the above?
The drive appears sound, at least none of the customers who contacted me ever said anything negative about that aspect. The ECUs were stock GM ones from what I read, with code revised to remove O2 sensor inputs for operation on 100LL and possibly turn off other chassis sensor inputs which are not on the aircraft. I read where they were resetting open loop AFRs at higher power settings (leaner) in an attempt to reduce cruise FFs.
This is of particular interest to me as we have the LS376/480. Titan claims fuel flows of 13 gph, but this is at a very reduced power setting, 2800 rpm. That would work out to .4 lbs/hr/hp. That will give me a burn of nearly 16 gallons/hour at 10,000 feet MSL, WOT, 3700 rpm (Max Cruise Power). Just hope we are going fast, real fast!
I actually figure 13 to 18 gph. That is a bit high, and I understand the motivation to reduce FF.
I just spoke with Robinson. He said to figure 18 gph in a high power cruise setting. He also said to run the engine at or above 3600 rpm in cruise, claiming that running the engines too slow is hard on them.
That flies in the face of what Titan is saying, claiming that a 2600 to 2800 rpm cruise is better for the LS3.
Who is correct?
I would hazard a guess that the answer is it depends.
I have heard and seen that with the stock computer many engines have problems if they are only run at minimal power by grandma inside the city limits and never pass 25MPH.
The solution, leave them in low and take them out on the highway for 30 minutes. A few mechanics said it was caused by the emission settings.
Beyond the hearsay, I know of two examples that match the comments above. A family friend of my parents and her neighbor both have Subaru Legacy cars. Neither drives on a highway, barely hit 35 in Sun City AZ (retirement community for old people). One has a car which was race tuned by her grandson and he raced for a year before giving to her. The other has a stock from factory. The stock car had emissions, and deposit problems after a few years. Solution was to open it up on the highway. The race tuned car never had problems.
Note: This is all hearsay. So take it with a grain of salt.
Separate names with a comma.