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  #21  
Old 03-19-2014, 04:09 PM
Bartman Bartman is offline
 
Join Date: Mar 2006
Location: NW San Antonio Boerne Stage Airfield 5C1
Posts: 160
Default Bobby

Bobby built the O-360 in my RV8. in 2011 it now has 300 hr on it and doing very well. Good guy too.
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  #22  
Old 03-20-2014, 11:11 AM
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flyingriki flyingriki is offline
 
Join Date: Sep 2008
Location: California
Posts: 697
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Bobby,
Can you give me some advice on compression and pistons? Am planning to go 10:1 and have two P-Mags. Any worries there other than not running really hard down low? I understand it's best not to lean too agressively too but since I'm stuck with a carb I wondered if that's still an issue.

Ceramic coated pistons, why and what are the drawbacks? Seems good to keep oil temps down but then maybe too much heat around the valves and CHT issues?

Thanks!
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  #23  
Old 03-24-2014, 07:44 AM
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Titan-Xpert Titan-Xpert is offline
 
Join Date: Mar 2014
Location: San Antonio Tx
Posts: 51
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Quote:
Originally Posted by flyingriki View Post
Bobby,
Can you give me some advice on compression and pistons? Am planning to go 10:1 and have two P-Mags. Any worries there other than not running really hard down low? I understand it's best not to lean too agressively too but since I'm stuck with a carb I wondered if that's still an issue.

Ceramic coated pistons, why and what are the drawbacks? Seems good to keep oil temps down but then maybe too much heat around the valves and CHT issues?

Thanks!
Several years ago we did a bunch of propeller testing on our RV-8 with Hartzell .Those guys gave us a real eye opening education about harmonic vibrations that tend to be aggravated by high compression .Certain prop, crank and high compression combinations create these vibrations (what a bell does when you hit it with a hammer) you usually cannot feel it in the seat of your pants. It causes fatigue in the prop and crank which causes them to get harder and harder until one or the other cracks and eventually fails.
Certified aircraft engine, propeller and compression combinations have a vibration survey done to identify the rpm’s that these harmonics are the most intense. This is why certain rpm’s are restricted for continuous operation and part of the reason why these engines can go to 2000hrs between overhauls without failures of the prop or crank.
At the end of our testing with Hartzell we were concerned about a 250 flight hour prop our airplane came with. We took it in to be inspected by a prop shop in San Antonio. They condemned it for hardness.
The lesson I learned from this is be weary of high compression engine propeller combinations that have not been surveyed. You truly will be an Experimental test pilot.
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  #24  
Old 03-24-2014, 08:34 AM
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flyingriki flyingriki is offline
 
Join Date: Sep 2008
Location: California
Posts: 697
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Quote:
Originally Posted by Titan-Xpert View Post
Several years ago we did a bunch of propeller testing on our RV-8 with Hartzell .Those guys gave us a real eye opening education about harmonic vibrations that tend to be aggravated by high compression .Certain prop, crank and high compression combinations create these vibrations (what a bell does when you hit it with a hammer) you usually cannot feel it in the seat of your pants. It causes fatigue in the prop and crank which causes them to get harder and harder until one or the other cracks and eventually fails.
Certified aircraft engine, propeller and compression combinations have a vibration survey done to identify the rpm’s that these harmonics are the most intense. This is why certain rpm’s are restricted for continuous operation and part of the reason why these engines can go to 2000hrs between overhauls without failures of the prop or crank.
At the end of our testing with Hartzell we were concerned about a 250 flight hour prop our airplane came with. We took it in to be inspected by a prop shop in San Antonio. They condemned it for hardness.
The lesson I learned from this is be weary of high compression engine propeller combinations that have not been surveyed. You truly will be an Experimental test pilot.
Will be running a composite prop. More concerned about detonation, manifold pressure limitations, proper leaning and the effect of elevation on all these. How much compression could become an issue with the metal props?
Thank you.
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  #25  
Old 03-24-2014, 03:06 PM
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Titan-Xpert Titan-Xpert is offline
 
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Location: San Antonio Tx
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Quote:
Originally Posted by flyingriki View Post
Will be running a composite prop. More concerned about detonation, manifold pressure limitations, proper leaning and the effect of elevation on all these. How much compression could become an issue with the metal props?
Thank you.
We were running 9:1 and backed off to 8:5 based on the Hartzell data. We also tested one of their composite props it had a similar harmonic issue just at a different frequency
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  #26  
Old 03-25-2014, 05:32 AM
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Mark Dickens Mark Dickens is offline
 
Join Date: Apr 2012
Location: Collierville, TN (KFYE)
Posts: 1,020
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I am seriously considering a IOX-370 with horizontal cold air induction for my -8, but have been warned that the ECI cold air induction may present an issue with exhaust pipe fit. Tentatively planning a Vetterman 4 pipe system. I've heard that the Superior sump works better with this setup. Any insight or advice?
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Titan IOX-370, Dual P-Mags, AFP FM200A FI, Sensenich GA Prop
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  #27  
Old 03-25-2014, 06:01 AM
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Weasel Weasel is offline
 
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Location: Brooksville, MS
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Quote:
Originally Posted by NovaBandit View Post
Any chance of a 540, or something comparable for an RV10?
How about a stroked 540 crank? Something around 580-600 cid.
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  #28  
Old 03-25-2014, 06:10 AM
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Kahuna Kahuna is offline
 
Join Date: Dec 2004
Location: Gold Hill, NC25
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Quote:
Originally Posted by Mark Dickens View Post
I am seriously considering a IOX-370 with horizontal cold air induction for my -8, but have been warned that the ECI cold air induction may present an issue with exhaust pipe fit. Tentatively planning a Vetterman 4 pipe system. I've heard that the Superior sump works better with this setup. Any insight or advice?
Mark we have this setup on Jerry Morris' RV-8 on our team. It is tight, like all horizontal inductions. But it does fit. No worries. And yes you will want the 4 pipe. We also have the inverted system on this as well.
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  #29  
Old 03-25-2014, 06:39 AM
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Geico266 Geico266 is offline
 
Join Date: Feb 2005
Location: Huskerland, USA
Posts: 5,856
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Bobby, glad to see you joined "The Force".

I am pretty sure I talked to you about my IOX-360. I was having a back firing issue running ROP. It went away when I switched to one mag. I put in all new injectors and 90% of the problem went away without any fuel pressure adjustment. Called it good enough since I run LOP most of the time.

The oil consumption (when the oil level it over 6qts) is high so I am adding an ASA separator next week. The previous owner ran his oil levels down to 4.5 qts and there was little blow by, but you didn't think that was a good idea so I am taking measures to get it back up to 6 or 7. Looking forward to a clean belly.

I have a question about oil pressure. Currently, it is running around 80 PSI in flight. If I backed it down to 65-70PSI would that help reduce blow by?

Quick starting, and a very smooth running engine that makes good power. Thanks! Runs good on 91 octane car gas also.

Here is a link to the thread I started about the rough running problem.
http://www.vansairforce.com/communit...d.php?t=107998

Again Welcome!
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RV-7 : In the hangar Thank You Marco & Jenny
RV-10 : In the hangar
RV-12 : Built and sold
RV-44 : 4 place helicopter on order.

Last edited by Geico266 : 03-25-2014 at 06:53 AM.
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  #30  
Old 03-25-2014, 07:11 AM
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Mark Dickens Mark Dickens is offline
 
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Location: Collierville, TN (KFYE)
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Quote:
Originally Posted by Kahuna View Post
Mark we have this setup on Jerry Morris' RV-8 on our team. It is tight, like all horizontal inductions. But it does fit. No worries. And yes you will want the 4 pipe. We also have the inverted system on this as well.
Mike, just curious, which injector was selected for his plane?
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First Flight 11/20/2016
www.marksrv8.com
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