Gang,

I am new to the list and seeking input from the expanse of knowledgeable people out there who really push this engine hard.

Summary: This post is a bit long so here is the summary. I am building an airplane and planning on using an LS-1 engine. I am looking for a MAX of 300 HP (see below) and reliability is obviously very important. Here is my ask to the group:

1) What are the common failure points in the LS-1 engine? Is it the water pumps, the ECU, etc.
2) I am good with a wrench, but the reliability question suggests it might be better to have an engine shop build up the engine and dyno test it. Recommendations?

Overview

I am one of the many pilots who build their own airplane resulting in ~1000 new airplanes every year (See eaa.org for lots more). Use of auto engines in planes is common to achieve lower cost and capitalize on better technology. The use of autoengines has a sorted history with some excellent success and some not so excellent. Some will take a 250 HP engine, add a supercharger and other enhancements and run the engine at 300 HP. When you use an autoengine you typically take-off at 100% power for the first 10 minutes and then run at 55%-75% power during cruise. This would suggest that that 250 HP engine is running at 225 HP (90% of 250 HP) during cruise for hours on end. Not exactly what it was designed for and as you might guess, it eventually breaks and the results are not good.

The other approach is to take an engine like the LS-1 and downgrade it. An LS-1 crate engine can generate ~345 HP. If it is run up to 300 HP at takeoff and cruise is at 225 that is 62% of the engine’s capacity; A much safer approach. Many people have done this with the LS-1 so this isn’t a new approach. Basic rules when using an autoengine:

1) You need an transmission or a Power System Reduction Unit (PSRU). Think of it a transmission with 1 gear that reduces the RPM by 1.5 to 2.0X.
2) Weight is a factor. The lighter the better. Hence an LS-1 with an Aluminum block is very desirable.
3) Reliability is perhaps the most important factor, the reason is obvious. If your vet breaks down you can coast to the side of the road. I would need to find a road, field, etc.
4) The power is dictated by the airframe. My airframe will only take up to 300 HP. More and I’ll rip the wings off.
5) The purpose of the propeller is to convert crankshaft thrust to forward thrust. The propeller must be matched to the PSRU, engine, airspeed and airframe. I will be using a custom propeller.

So how can you help?
1) Given what I am doing where do you see that I might consider after-market enhancements? I have been told to consider a better water pump. I have been told to consider forged piston heads? Does this make sense? Who’s would be recommended. Other recommendations?
2) As reliability is critical I would prefer to let an expert do the work. I have lots to manage with design of the engine mount, propeller, and other airframe elements. I am seeking a knowledgeable organization that can address the above, particularly the reliability changes, and dyno test the system. Often people get nervous when you talk to them about this as we have too many lawyers in the world. I’m looking for a good engine, not a legal battle. There is a complete process for testing prior to flight that will sort out any issues before I fly.

Thanks for reading and I look forward to your input.

 

While I have nothing useful to add to this, I see that your in Denver... If you ever get this project off the ground I'd love to check it out!

 

There are quite a few flying enthusiasts here. This would probably net better results in the lounge though.
I may be wrong, but wouldn't the rotating mass of the prop also knock the total output back some?

 

Nothing to add :/ but that's so crazy, I never knew auto engines where used .. Wow .. Just learned something for the day

 

Hope you saw this:
https://ls1tech.com/forums/conversio...onversion.html

 

My good buddy is a pilot, and it's always fun to talk with him about the engines. We were just plane shopping on Tuesday. He was looking at the Cirrus SR20, but does not like the narrow wing profile and how terribly they respond to icing. I digress...

You couldn't pay me to fly a built engine in an airplane, unless you knew for sure everything about the build was quite literally perfect. Reliability is by far #1, everything else a distant second of course, unless you have terminal cancer. What fuel would you be using?

Have you considered other V8 aluminum engines? 90s Lexus 1UZFE, 2UZFE, are some of the most reliable engines ever made, going 300k on conventional oil, and being adequately broken in at that point. They are insanely strong, DOHC, etc. They quite literally do not break, and you can up the power by virtue of ram air, headers (highly restrictive stock), etc.

Are you going to control fuel lean/rich like a normal airplane engine, or do a more car-like approach of letting the ECU do a lot of the work? The good news is you can tune the engine ECU on the ground, watching exhaust gas temperature and everything else very carefully. Run it for several hours at high output, and I bet that with the right balance of ignition timing and fuel, you will be able to keep cylinder temperatures rock solid (and you'll find out quickly if you don't). The UZFE engines are so cheap, you will have the luxury of trial and error BEFORE you go up.

Might want to consider a very simple aftermarket ECU either way. Custom headers will almost certainly be mandatory no matter what you do. Looking forward to hearing what you end up doing. Bravo to you for building your own plane.

 

Thanks for the reply's. I was familiar with the Seebee conversion. He has not taken that to a commercial product that costs > $30k based on one report and another suggests it is around $60k. I can buy a whole airplane for that cost. But I must admit he has been very successful having logged more hours on an LS-1 than any other conversion I am aware of. His PSRU is very heavy and wouldn't fit my plane, but it is an excellent example of the kind of conversion I am seeing.

To the comment... Use an aftermarket ECU that is "simple" Who's would you recomend?

 

To the question "Wouldn't the rotating mass of the prop also knock the total output back some?" True. Any mass will do this. Prop's come in different weights, sizes, etc. The length of the prop blades has a fair bit to do with this as well. There are 2 kinds of props, fixed pitch and variable pitch. Fixed composite prop's are light and variable pitch (Constant speed as they are known) are heavy and expensive. A fixed pitch wooden prop that is laminated with with fiber glass runs $2-3k and weighs ~15-20 lbs. A variable pitch costs $12-15k and weighs 60 lbs. One can generally achieve better performance from a variable pitch across the entire flight envelope. However, most pilots spend 90% of their time flying at the same power setting/speed. Is it worth the difference in cost? One does give up some perfomance in climb and takeoff run with a fixed pitch prop. If this can be kept acceptable why spend the extra $$$ and absorb the extra weight. As I mentioned earlier the Prop, PSRU, engine and airframe all have to work together... part of the equation.

 

ClimberD,

You mentioned that custom heads would almost certainly be manditory.... OK I'll bite why? Is there something wrong with the stock heads?

 

The only thing in My opinion that I have read about on here that could potentially cause the engine to quit running would be the oil pump or it could be other engine parts wearing and the metal flakes damaging the oil pump . I know with airplanes You are required to rebuild the engine every so many hours , I know You know this as well but I would make sure and install new oil pump when rebuilding . Most of the threads I've read about oil pressure issues stated the engine had over 100k . But other than that the engines with the stock factory controlling system (PCM, wiring, sensors, sequential fuel inj) are among the most reliable engines anywhere .

 

Anything would work, as most ECUs are pretty simple by nature. Crank and cam triggers in, throttle position, coolant temp and perhaps knock sensors (no idea how much resonance a prop would produce), EGT perhaps, then fuel and ignition outputs... my only concern is the stock GM PCM has many compensations and safety controls (which are great in an emissions-controlled automobile running low-octane fuel), as where in an airplane I'm assuming you want the most consistent, straightforward and predictable controls possible. Any PCM including the GM PCM could be made to run simply, but the great thing about aftermarket ECUs is they are designed to be very simple, but with the option to add on complexity only when you want. So a reverse approach to accomplishing a similar end. Name any brand, should work fine. Megasquirt v3 comes to mind. Pre-assembled board, live tuning, massive online support, can be configured any which way, accepts any sensors and outputs, high resolution, inexpensive, does whatever your mind can come up with. Take what I write critically, just throwing out ideas because this sounds like a very interesting project. I wish I could talk my friend into doing this, but he wants to buy a plane straight out of the factory, maybe a slightly used one, with zero alterations and double everything. Come on, you don't need two Garmins...

Custom headers, not heads

Speaking of headers, have you given any thought to turbo(s)? Some companies still make super reliable turbos... though I suppose you would only want to cross that bridge if you need to.

 

Well if your MAX is 300hp, then forget about the LS1 because it makes way more than that. look into an aluminum 5.3

 

Look at WWW.Quietaviation.com

Also, I'm about to do some interior work on a composite experimental with an LS1. It's about the size and looks of a Cirrus. I'll have to get pics and post them here. Factory stock(new crate motor) including PCM.

 

The only suggestion that I have to add, is to give Katech, inc. a call. This seems like something that might be right up their alley.

http://www.katechengines.com/

 

Wet sump oil system of an ls engine work will it? I would think in a steep climb or banking turns one would worry about oil pump starvation. Maybe dry sump?

 

The FAA has only certified brand-new GM LS engines out of the crate. No modifications or add-on's. Furthermore, they do not allow rebuilds of the engines, since no FAA certified rebuild facilities are available for the engines. When the engine reaches it's maximum hours, you just pull it out and replace it with a brand new one. You can not just start adding aftermarket equipment to ANY aircraft engine without FAA certification of that modification unless it is on an experimental aircraft.



Regards, John McGraw

 

Man, who do they sell the used engines to? If they limit these things to 180 HP output and I would imagine the maximum number of hours is something ridiculously small, then these would be premo swap motors.