Originally Posted by Matt Monson
Are you friends with Bubba?
The turbo really is discretionary. The vast majority of engines that CCR builds for the homemade airplane crowd are NA Ej22e's. They install a Delta cam in them that gives them an extra 15hp over stock and when freed from the restrictions of the factory intake and exhaust they are fine for most of those guys.
With a non-restrictive intake and exhaust along with a set of cams, an otherwise stock Ej25 engine will make more than 200bhp at sea level. You can read all about my car if you go search in the NA forum, but I will give you the relevant details to try and convince you that you do not need to turbocharge that engine for your use.
I live at 5000ft. When I had just an intake, headers with high flow cat, and cams, along with lightweight flywheel and pullies, I put down 119 whp on our local dyno. That's an uncorrected number. That's the real power up here without any compensation for altitude to make it look like an SAE sea lever number. We use a very aggressive dyno here that it known for reading low. Conservative numbers generally put the drivetrain loss of our AWD drivetrains at about 35%. Based on that, my engine was actually making 183chp at that point. That hits your number with a bit to spare. That was on a stock factory ECU with no additional tuning control.
So, what I am saying here is that you very well may be able to avoid the added weight and the complications of a turbo. It's your project and you will do what you want, but I just want you to know that it really isn't required based on the performance parameters you have presented to us.
Your candor and interest on the project is most appreciated. If I can indeed make that kind of horsepower up to 5,000 feet, I am more than happy to drop the turbo. Really! Here is the snag... Given my situation, with time available to develop something to help the many other owners sick of underpowered unreliable powertrains, it is in all of our best interest to generate a one-size fits all, so that it can be duplicated and made available as a kit. But if the turbo can go, ALL THE BETTER.
But what about those guys at 10k feet elevation who are experiencing the factory's crappy failing "ACIS" supercharger, with blown pistons and shredding belts? Is a normally aspirated engine going to supply 170 horsepower on a 95 degree high humidity day? That's the rub. But if so, then great. Keeping in mind the ACIS only tries to maintain the factory sea level performance of their stated 150hp (really about 125 to 130 depending on who you talk to).
So what I am asking is...can or should I do both? Can I develop around the EJ25 w/o turbo...and add it back in for those who need it? Is it as simple as a head gasket change (reduce CR) and a turbo add and ECU programming? Or is there more to it? Or is it that I need to plan on entirely different EJ25's purpose built to be NA or turbo'd from the start?
For my own personal situation the EJ25 w/o turbo should work fine, I agree now. But I guess I would have to run it at higher rpm than I am comfortable with.
Matt you said "When I had just an intake, headers with high flow cat, and cams, along with lightweight flywheel and pullies, I put down 119 whp on our local dyno."
At what rpm? We need this engine to put out constant power, and if the power is up at the engine's max, it will melt down in short order. You street guys never put the demands on your engines that a helicopter does. Just reality. Constant versus intermittent.
My buddy developed his own helicopter from scratch using the EJ25, and I would be using his drivetrain design (google: Kinney HRH).
Hadn't put much thought into the intake and exhaust restrictions but I guess that is an important distinction.
So I guess if the weight can get into the ballpark (I suspect carbon fiber parts are in order to assist with this) and if the demanded output from the engine isn't over say, 75% of the engine's max output on a constant basis, this might work.
Coincindeltally I got a call back from a major air cooled engine builder. He thinks he can make over 200 hp easily. The problem with that is, these machines are covered in fiberglass panels. It would be a major engineering challenge to get air cooling to work. That alone would take 2-3 years of wrok and would likely fail. On top of an overstressed air cooled engine and the constant diligence required by the pilot due to the ease of overtemping.