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kearney
Joined: 20 Sep 2008
Posts: 563
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 Posted: Mon Jun 02, 2014 8:36 pm Post subject: 9:1 Compression Pistons |
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Hi
One of the engine options I have is using 9:1 positions rather than 8:1. I understand that there is a small HP gain with the 9:1 pistons.
For those with the 9:1 pistons, is there a significant performance bump. Has anyone had problems with detonation?
Cheers
Les
Sent from my iPhone
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Mon Jun 02, 2014 9:06 pm Post subject: 9:1 Compression Pistons |
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Les,
The standard compression is 8:5 to 1. All Lycoming engines at that
compression were certified on 91/96 octane avgas.
Most will run fine on 91-92 octane mogas. All of the angle valve higher
horsepower engines have 8.7 to 1 compression and require 100 octane
avgas. So you can pretty much be assured that 9 to 1 compression will
require 100 octane. Given that Van's does not recommend 260 hp on the
airframe, the only really benefit to more horses is climb capability.
Top speed with the 260 hp is around 210-212 mph TAS. Design flutter is
230 true air speed. How close do you want to shave that margin?
On 6/2/2014 9:36 PM, Les Kearney wrote:
| Quote: |
Hi
One of the engine options I have is using 9:1 positions rather than 8:1. I understand that there is a small HP gain with the 9:1 pistons.
For those with the 9:1 pistons, is there a significant performance bump. Has anyone had problems with detonation?
Cheers
Les
Sent from my iPhone
|
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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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pilotdds(at)aol.com
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| Posted: Mon Jun 02, 2014 11:03 pm Post subject: 9:1 Compression Pistons |
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FYI I just flew my second 10.Both have 2 blade hartzels the old one has 2 light speeds the new one has one.The old one has a 9 to 1 narrow deck the new one has standard 8.5 to one compression.gross weight is 1630 and 1612.The old one is noticeably more powerful,I don't want to give absolute numbers but there is a difference in both climb and cruise.
Sent from my iPhone
| Quote: | On Jun 2, 2014, at 6:36 PM, Les Kearney <kearney(at)shaw.ca> wrote:
Hi
One of the engine options I have is using 9:1 positions rather than 8:1. I understand that there is a small HP gain with the 9:1 pistons.
For those with the 9:1 pistons, is there a significant performance bump. Has anyone had problems with detonation?
Cheers
Les
Sent from my iPhone
|
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jesse(at)saintaviation.co
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| Posted: Mon Jun 02, 2014 11:44 pm Post subject: 9:1 Compression Pistons |
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The difference between 7:1 and 8.5:1 pistons at 2,575 rpm is 15 hp. I wouldn't expect the increase to 9:1 to be more than 5-10 hp, but it is an increase. If you're only running 100LL, which most 10's do, then you'd be fine with 9:1 and the tbo is still 2,000 hrs.
Jesse Saint
I-TEC, Inc.
jesse(at)itecusa.org
www.itecusa.org
www.mavericklsa.com
C: 352-427-0285
O: 352-465-4545
F: 815-377-3694
Sent from my iPhone
| Quote: | On Jun 3, 2014, at 1:57 AM, Jim Rore <pilotdds(at)aol.com> wrote:
FYI I just flew my second 10.Both have 2 blade hartzels the old one has 2 light speeds the new one has one.The old one has a 9 to 1 narrow deck the new one has standard 8.5 to one compression.gross weight is 1630 and 1612.The old one is noticeably more powerful,I don't want to give absolute numbers but there is a difference in both climb and cruise.
Sent from my iPhone
> On Jun 2, 2014, at 6:36 PM, Les Kearney <kearney(at)shaw.ca> wrote:
>
>
>
> Hi
>
> One of the engine options I have is using 9:1 positions rather than 8:1. I understand that there is a small HP gain with the 9:1 pistons.
>
> For those with the 9:1 pistons, is there a significant performance bump. Has anyone had problems with detonation?
>
> Cheers
>
> Les
>
> Sent from my iPhone
>
>
>
>
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bobw
Joined: 31 Mar 2014
Posts: 8
Location: Marquette, MI
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| Posted: Tue Jun 03, 2014 3:31 am Post subject: 9:1 Compression Pistons |
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Sorry - I missed something but where is it stated that Van's doesn't recommend a 260 HP for the RV-10??
Bob Wilson
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| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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Bob Wilson
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Kelly McMullen
Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ
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| Posted: Tue Jun 03, 2014 4:38 am Post subject: 9:1 Compression Pistons |
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Vans does not recommend ABOVE 260 hp. 260 hp is recommended as the maximum and what most RV-10s have. The parallel valve IO-540 does not come from Lycoming in stock certified form above that hp rating, but can easily be tweaked through higher compression, porting, cold air induction, etc to reach close to 300 hp, without using a turbo. Even turbo normalizing where one does not operate above published 75% power output(195 hp), but maintains it to a higher altitude, will push true airspeed up to 230 mph at around 12,000 ft, which is cited in a Vans paper as why you are flirting with the design limitations when you go to more horsepower.
On Tue, Jun 3, 2014 at 4:30 AM, Bob Wilson <bob(at)rjw.cc (bob(at)rjw.cc)> wrote:
[quote] --> RV10-List message posted by: Bob Wilson <bob(at)rjw.cc>
Sorry - I missed something but where is it stated that Van's doesn't recommend a 260 HP for the RV-10??
Bob Wilson
--
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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Kelly McMullen
A&P/IA, EAA Tech Counselor
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jdriggs49(at)msn.com
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| Posted: Tue Jun 03, 2014 5:31 am Post subject: 9:1 Compression Pistons |
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I have a Barrett with 9:1 pistons and cold air induction. The only way I can get near the design limit is in a dive. No way can you get there in any kind of level or near level cruise. Yesterday I had to set the autopilot to the absolute top speed and it took quite a steep dive to get to 200 kts.
Nice thing about it that you can go to gross weight and have NO problem getting off on a hot day. These Barretts with 9:1 and cold air induction are real "hosses".
Date: Tue, 3 Jun 2014 05:38:00 -0700
Subject: Re: RV10-List: 9:1 Compression Pistons
From: apilot2(at)gmail.com
To: rv10-list(at)matronics.com
Vans does not recommend ABOVE 260 hp. 260 hp is recommended as the maximum and what most RV-10s have. The parallel valve IO-540 does not come from Lycoming in stock certified form above that hp rating, but can easily be tweaked through higher compression, porting, cold air induction, etc to reach close to 300 hp, without using a turbo. Even turbo normalizing where one does not operate above published 75% power output(195 hp), but maintains it to a higher altitude, will push true airspeed up to 230 mph at around 12,000 ft, which is cited in a Vans paper as why you are flirting with the design limitations when you go to more horsepower.
On Tue, Jun 3, 2014 at 4:30 AM, Bob Wilson <bob(at)rjw.cc (bob(at)rjw.cc)> wrote:
[quote] --> RV10-List message posted by: Bob Wilson <bob(at)rjw.cc>
Sorry - I missed something but where is it stated that Van's doesn't recommend a 260 HP for the RV-10??
Bob Wilson
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philperry9
Joined: 23 Nov 2011
Posts: 381
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| Posted: Tue Jun 03, 2014 6:24 am Post subject: 9:1 Compression Pistons |
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Mine produced 285HP with one mag and one lightspeed. Still not flying, but those came from a break-in session, in a test cell, prior to being delivered to me. I was still given a full warranty and TBO of 2,000.
Phil
On Tue, Jun 3, 2014 at 8:30 AM, Danny Riggs <jdriggs49(at)msn.com (jdriggs49(at)msn.com)> wrote:
[quote] I have a Barrett with 9:1 pistons and cold air induction. The only way I can get near the design limit is in a dive. No way can you get there in any kind of level or near level cruise. Yesterday I had to set the autopilot to the absolute top speed and it took quite a steep dive to get to 200 kts.
Nice thing about it that you can go to gross weight and have NO problem getting off on a hot day. These Barretts with 9:1 and cold air induction are real "hosses".
Date: Tue, 3 Jun 2014 05:38:00 -0700
Subject: Re: 9:1 Compression Pistons
From: apilot2(at)gmail.com (apilot2(at)gmail.com)
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Vans does not recommend ABOVE 260 hp. 260 hp is recommended as the maximum and what most RV-10s have. The parallel valve IO-540 does not come from Lycoming in stock certified form above that hp rating, but can easily be tweaked through higher compression, porting, cold air induction, etc to reach close to 300 hp, without using a turbo. Even turbo normalizing where one does not operate above published 75% power output(195 hp), but maintains it to a higher altitude, will push true airspeed up to 230 mph at around 12,000 ft, which is cited in a Vans paper as why you are flirting with the design limitations when you go to more horsepower.
On Tue, Jun 3, 2014 at 4:30 AM, Bob Wilson <bob(at)rjw.cc (bob(at)rjw.cc)> wrote:
[quote] --> RV10-List message posted by: Bob Wilson <bob(at)rjw.cc>
Sorry - I missed something but where is it stated that Van's doesn't recommend a 260 HP for the RV-10??
Bob Wilson
--
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Tue Jun 03, 2014 12:26 pm Post subject: 9:1 Compression Pistons |
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Danny,
You are already at/over the limit and pushing your luck. The limit is
TRUE AIRSPEED, not INDICATED airspeed.
You need to understand that control flutter is a function of true
airspeed, which at most any altitude above sea level is higher than
indicated airspeed. 200kts IS 230 mph, you were at indicated in that
dive and above the design flutter true airspeed which is 230 MPH.
BE CAREFUL out there. One RV-10 lost this week is way too many,.
On 6/3/2014 6:30 AM, Danny Riggs wrote:
[quote] I have a Barrett with 9:1 pistons and cold air induction. The only way
I can get near the design limit is in a dive. No way can you get there
in any kind of level or near level cruise. Yesterday I had to set the
autopilot to the absolute top speed and it took quite a steep dive to
get to 200 kts.
Nice thing about it that you can go to gross weight and have NO
problem getting off on a hot day. These Barretts with 9:1 and cold air
induction are real "hosses".
------------------------------------------------------------------------
Date: Tue, 3 Jun 2014 05:38:00 -0700
Subject: Re: 9:1 Compression Pistons
From: apilot2(at)gmail.com
To: rv10-list(at)matronics.com
Vans does not recommend ABOVE 260 hp. 260 hp is recommended as the
maximum and what most RV-10s have. The parallel valve IO-540 does not
come from Lycoming in stock certified form above that hp rating, but
can easily be tweaked through higher compression, porting, cold air
induction, etc to reach close to 300 hp, without using a turbo. Even
turbo normalizing where one does not operate above published 75% power
output(195 hp), but maintains it to a higher altitude, will push true
airspeed up to 230 mph at around 12,000 ft, which is cited in a Vans
paper as why you are flirting with the design limitations when you go
to more horsepower.
On Tue, Jun 3, 2014 at 4:30 AM, Bob Wilson <bob(at)rjw.cc
<mailto:bob(at)rjw.cc>> wrote:
Sorry - I missed something but where is it stated that Van's
doesn't recommend a 260 HP for the RV-10??
Bob Wilson
--
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
|
_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD |
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