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any issues with combination IO-375 and Hartzell CS?

KayS

Well Known Member
Hi All,

i have to certify my 7 with the german civil aviation authorities. Seems the responsible official is somewhat picky when it comes to engine and the one i use (IO375 M1S) is unknown to him. He was asking if there are any troubles or special characteristics with this engine in combination with the 72" Hartzell BA CS Propeller (HC-C2YR-1BF) i am aware of. Things like vibrations / RPM's to avoid etc.

Could anybody with this setup provide some hints? best with an RV7 airframe.

Best Regards
Kay
 
You might start your search by contacting the manufacturer of the engine as stated on the dataplate. Bevan.
 
Prop TCDS

Take a look at this:
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/d7115816308185568625843f00661353/$FILE/P-920_Rev39.pdf

Unless there has been a more recent update, you won't find the IO-375 listed. I have the same engine/prop as you and from the discussion I had with my engine shop when I purchased it I was told the IO-375 M1S is equivalent to the IO-360 M1B except with a cold air sump. If you call Hartzell they will probably tell you that unless your specific engine and prop combination is listed in the TCDS stating what if any, RPM restrictions exist, you should honor the restrictions for the nearest equivalent engine. Note that restrictions can vary with blade model.

J. Baker
RV8
 
You might start your search by contacting the manufacturer of the engine as stated on the dataplate. Bevan.

the engine manufacturer will tell that they have no info with this propeller and the propeller manufacturer tells me vice versa.
 
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Take a look at this:
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/d7115816308185568625843f00661353/$FILE/P-920_Rev39.pdf

Unless there has been a more recent update, you won't find the IO-375 listed. I have the same engine/prop as you and from the discussion I had with my engine shop when I purchased it I was told the IO-375 M1S is equivalent to the IO-360 M1B except with a cold air sump. If you call Hartzell they will probably tell you that unless your specific engine and prop combination is listed in the TCDS stating what if any, RPM restrictions exist, you should honor the restrictions for the nearest equivalent engine. Note that restrictions can vary with blade model.

J. Baker
RV8

the io 375 is very similar to the 360 but has more displacement due to longer stroke. and that could change everything when it comes to resonance frequencies etc.
 
Here is a thread I started in Prop section with Hartzell Application guide.

http://www.vansairforce.com/community/showthread.php?t=177893

Does this engine have dampened crankshaft? Do you have electronic ignition. These are all factors. Is this angle or parallel valve engine? What Prop blades do you have... you listed hub only...

The RPM and MAP limits are driven by the Prop and the Application guide will give you a good start. Then go to the TC or type cert data sheet for the Prop for more "official" data that will impress and influence your Aviation authorities. READ ALL THE NOTES both in the TC.

You have an experimental engine and Hartzell has net tested ever new latest greatest engine... You will have to get one that is close. The prop although developed for RV's and experimental market is now applicable to certified planes. The application guide will show you that. Again this might impress your regulatory agency.

Bottom line find the most applicable or similar engine and prop combo (with or without electronic ignition as you have). You WILL have RPM and MAP limits. The biggest drivers of prop harmonics and RPM/MAP limits is dampened crank and EI.
 
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Call Hartzell - it has been tested

I talked to Bart Lalonde at Aero Sport Power back in 2009 about this before i ordered my -375 from him. Hartzell had tested the low compression version of this engine (the version I have) with the older Hartzell CS prop - not the blended airfoil. Basically tested out the same as a -360 if I recall. Suggest trying to call Hartzell and see if they will talk to you about their results - worth a shot.
 
I had a similar information exchange as Dan, except with Hartzell. Spoke to a technical rep there over the phone 6-8 months ago. He acknowledged they hadn't published that engine/prop combo, but had some information on it for low-compression. It lined up nearly the same as -360 with that prop. There was an rpm range that was not to be continuous use (like many others) that I don't have with me.

FWIW...I own an Aerosport IO-375, low compression, and plan to hang the same Hartzell prop you describe.

Also suggest a call to Hartzell to verify.
 
I have a call into Tech Support at Hartzell asking about:
  • IO-375, low compression, ECI Tapered Nickel Cylinders
being paired with
  • Compact hub Constant-speed prop for (I)O-360 (180/200hp) 72" PROP C2YR-1BFP/F74972 listed on Van's site.
Will report back once information is received.
 
When I switched to the IO370 high compression last year I talked with Les Dowd at Hartzell, he convinced me to switch to the newer BA blade from the original 7496 BA blade I had. He had no concerns with the thicker 7497 blade and the 370 with counter balanced crank. I do run dual Bendix mags.

Not sure how ASP gets 375 cubes when they source/use the parts from the Titan 370

Ref Hartzell application guide 159 for more info.
 
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Marketing

Not sure how ASP gets 375 cubes when they source/use the parts from the Titan 370

The (undamped) crankshaft in my low compression IO-375 is ECI part # AEL37001-1 which I believe is the same # Titan uses in the low compression IOX-370.

I'm sure "375" just sounded better than "371.32". Aerosport rounded up - Titan rounded down. ;)
 
The (undamped) crankshaft in my low compression IO-375 is ECI part # AEL37001-1 which I believe is the same # Titan uses in the low compression IOX-370.)

Personal opinion only, but I agree. If you take out your calculator and compare the actual swept volume you might conclude that the claimed performance figures are snake oil. Certainly the questions could be asked why pay a 25% premium for the engine?

There is a bit of history with this engine. Originally it was non-counterweighted. Aerosport told me at one stage that at least one in the US shed a tip. Now you can only buy them in counterweighted versions.

Similarly there are a number of different Hartzell props. The previous version was supposed to be faster. The blades were beefed up a bit for these sorts of applications but slightly slower as a result?

The 370 crankshaft has a slightly larger stroke, such that attention has to be paid to the case in order to make sure the rod bolts don't hit the decks. Also the cam had material removed to clear the little end. One of our local engine shops claims to have pulled one down and discovered that the assembler had ground the ends of the rod bolts to clear. The case was cracked etc.

The low compression option uses experimental pistons, while the high compression option uses O-320 pistons. The difference being the piston deck height.

I had one on my 7A for 12 months - low compression and no counterweights. Exact same setup airframe, sump, ignitions, etc. It MIGHT have been 3kts faster, but it burnt ~3l/hr more to do it (LOP).

This is the rub - If the power changes are significant, it may well be a significant engineering issue. If the improvements is minor, is it worth paying the premium?
 
Heard back from Aerosport and Hartzell re: IO-375

I am not speaking for Aerosport Power and/or Hartzell Propeller, so please investigate the following for yourself. This is only my understanding.

Hartzell, in combination with Aerosport Power, informed me of the following IO-375 engine with propeller (p/n below) limitation for this combo:

  • Recommended Compression Ratio ≤ 8.7:1 on Non-Counterweighted
  • HC-()2YR-1BFP/F7497()
  • 74 to 72" Diameter
  • Continuous operation is prohibited above 24 inches of manifold pressure between 2350 and 2550 RPM.
Note: Standard mags were used to arrive at this information. Hartzell also notes electronic ignitions, different cranks, compression ratios, etc. can have an effect and change the above limitation. Different information exists, including higher compression engines with counterweighted cranks.

I have to thank Darren at Aerosport Power, plus Kevin Ryan and Mike Trudeau at Hartzell for this information. Darren said they plan to list this information on their site sometime in the near future.
 
Thanks!

. . . . . . . .
Hartzell, in combination with Aerosport Power, informed me of the following IO-375 engine with propeller (p/n below) limitation for this combo:

  • Recommended Compression Ratio ≤ 8.7:1 on Non-Counterweighted
  • HC-()2YR-1BFP/F7497()
  • 74 to 72" Diameter
  • Continuous operation is prohibited above 24 inches of manifold pressure between 2350 and 2550 RPM.
. . . . . . .

Sean, Thanks for this! I had sent E-mail to Hartzell years ago asking about data from their test back in the day - but I never got any response. This is even better since it specifies the prop I actually have. It's interesting that the MP/RPM limitation is identical to the 200 HP Angle Valve -360.
 
I contacted Hartzell in Jan 2017 re my RV-8, IO-375, 8.5:1, HC-C2YR-BFP/F7497-2, dual P-Mag combination. Like SeanB they indicated that since they hadn't tested this combination to use the most restrictive placard ie "Continuous Operation Is Prohibited Above 24 Inches of Manifold Pressure Between 2350 and 2550 RPM".
 
Big thanks to you guys contributing to the topic!!!

"Continuous operation is prohibited above 24 inches of manifold pressure between 2350 and 2550 RPM" - that should be a great starting point to work with. I do have dual EI etc. so i guess my setup could be a bit different.

Other Question: Can you "feel" the problamtic MAP/RPM-Setting? i remember flying in a lycoming powered PA28 with RPM-restriction but it wasn't obvious that these RPM ranges should be avoided for longer periods of time, at least for me...

as mentioned earlier, there are a lot of factors affecting prohibited RPM ranges (engine type, ignition, prop hub, mount, airframe, phase of the moon etc.) and at the end you have to find out for your RV by yourself. What's your procedure to identify these ranges? Just by feel? Or is it somewhat quantifiable?
 
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