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  #31  
Old 09-08-2014, 07:00 AM
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Originally Posted by rv6ejguy View Post
The top Sport Class engines have been putting out over 750+hp for a number of years now and both the direct drive Lycoming 540 and Conti 550s have been reliable if screwed together properly and operated properly, even with MAP as high as 75-80 inches and 3200 rpm. The fuel and spark department has to be dead on as do the turbos, ADI, spray bar systems. There is no room for error or malfunction at these power levels.

Success depends a lot on much high power flight testing prior to the event to make sure everything is just right. With the GTSIO, I don't think anyone has proven the reliability of the gearbox at these hp levels. Potentially, the geared engine is the way to go to make a lot more power and improve prop efficiency but there is some work to do to make it reliable. Darryl Greenamayer didn't have good success with his attempts at using a geared Conti a few years back either.
Darryl/Andy Lancair didn't have any gearbox issues that I know of after they switched from a custom planetary setup welded on the nose of an IO-550 case to the GTSIO case with the lousy Conti spur reduction. Part of the compromise was switching to a less-efficient 4 blade MT prop to keep the gearbox alive, but they were having trouble pushing enough fuel last I knew.

Kevin has that all sorted out . Still engine builder and setup has a huge part to do with longevity during a race. I don't know any details, but a failure on the second test flight would lead me to guess (GUESS) that they weren't even too deep in the power when it stoppppped. I'm not super close to either program, but I've talked to both guys and had other indirect contact throughout the last few years since I've been to Reno. I'm not a fan of the GTSIO in this application, but I'm ready to have someone like Kevin prove me wrong...
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  #32  
Old 09-08-2014, 07:36 AM
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Any factual news about what broke, and why?
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  #33  
Old 09-08-2014, 10:18 AM
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Originally Posted by osxuser View Post
Darryl/Andy Lancair didn't have any gearbox issues that I know of after they switched from a custom planetary setup welded on the nose of an IO-550 case to the GTSIO case with the lousy Conti spur reduction. Part of the compromise was switching to a less-efficient 4 blade MT prop to keep the gearbox alive, but they were having trouble pushing enough fuel last I knew.

Kevin has that all sorted out . Still engine builder and setup has a huge part to do with longevity during a race. I don't know any details, but a failure on the second test flight would lead me to guess (GUESS) that they weren't even too deep in the power when it stoppppped. I'm not super close to either program, but I've talked to both guys and had other indirect contact throughout the last few years since I've been to Reno. I'm not a fan of the GTSIO in this application, but I'm ready to have someone like Kevin prove me wrong...
The stock Conti FI is unsuited to properly metering the fuel flows required at these hp levels and this is where many of their problems were, Andy and crew were changing jug after jug after almost every high power test flight. This was a well known problem which is why Mike Dacey switched to EFI in the Venture with the Conti 550. All those problems went away after this and he won the Gold Championship in 2010 and had no engine issues over the course of 3 race seasons, test flying and transiting the aircraft. In fact, the engine was untouched internally for 4 years (Lycon built).

The tiny planetary gearbox welded to the front of the case wouldn't have lasted even a few minutes at race power (and didn't) plus the engine never ran long enough at race power due to burned pistons/ FI issues to know if the stock Conti spur gear was capable of handling 900+hp and in unknown prop/gearbox TV territory (doubtfully IMO). This is more than double the output as installed in the C421.

Like I said, nobody has enough hours at these hp levels to prove that this is a reliable setup for racing. Best to get the thing on a dyno and flog it for a while at race power before putting in the airframe. The geared engines have the potential to make 20-25% more power than the direct drive ones but there are many unknowns running at 80 inches and 4000 rpm.

I hope Kevin or someone else continues to pursue the geared concept. With enough work, $ and testing, it should be able to be reliable.
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Last edited by rv6ejguy : 09-09-2014 at 08:11 AM.
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  #34  
Old 09-10-2014, 12:25 AM
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Right, I feel that both gear reduction and the IO-720 haven't had the engineering thrown at them to get them reliable at race power. With the resources Kevin has available to him, my hope is that he sets Relentless up with a nice IO580 or IO550 with a bunch of boost so he can race the next few years, and then pursues the geared engine with lots of ground running. If nothing else, the GP5 is a reminder that it's easy to lose your life that close to the edge.

I'm thinking the geared engineering might be better used on an LS7 than the 550. The IO-720 still peaks my interest though.
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  #35  
Old 09-10-2014, 06:53 AM
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Originally Posted by osxuser View Post
Right, I feel that both gear reduction and the IO-720 haven't had the engineering thrown at them to get them reliable at race power. With the resources Kevin has available to him, my hope is that he sets Relentless up with a nice IO580 or IO550 with a bunch of boost so he can race the next few years, and then pursues the geared engine with lots of ground running. If nothing else, the GP5 is a reminder that it's easy to lose your life that close to the edge.

I'm thinking the geared engineering might be better used on an LS7 than the 550. The IO-720 still peaks my interest though.
Yes, Kevin is in a good position now with Titan to come up with a powerful and reliable package for future years and I believe a 550 or 580 Conti would be the immediate path to pursue to get back on top of the pile.

Ultimately though, I agree that a liquid cooled, automotive solution is key to pushing the hp and speeds well above what they are now. I'm thinking more 700-900 inch Mountain motors with mild turbocharging. These would easily double the hp of the best current aircraft engines in the class. Of course Titan does not do liquid cooled V8s so that might not be in the cards for Relentless.

In the end though, success in racing comes to those who are well prepared and well tested, well prior to the event. You need confidence that everything will perform predictably and reliably come race day, not only with the powerplant/ prop, but also the airframe. The NXT is flutter validated to very high speeds so that is less of a worry than other airframes which are in somewhat unexplored territory. For sure, these speeds, altitudes, wakes and mid day turbulence present dangers most of us will never experience in our every day flying. I have deep respect for every pilot racing at Reno.

Looking forward to see Kevin to duke it out with the other RVs and Rockets in the RV8 anyway to see how the big inch four performs.
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  #36  
Old 09-10-2014, 08:00 AM
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Originally Posted by rv6ejguy View Post
Looking forward to see Kevin to duke it out with the other RVs and Rockets in the RV8 anyway to see how the big inch four performs.
Must be sandbagging. So far, all the RV-8's are close in qualifying.

Ya'll see that Lavelle ripped off a lap at almost 410?
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  #37  
Old 09-10-2014, 08:22 AM
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Originally Posted by DanH View Post
Must be sandbagging. So far, all the RV-8's are close in qualifying.

Ya'll see that Lavelle ripped off a lap at almost 410?
Dan,

We are all within a 3-4mph window... great racing! I had a horrible rookie Qual, but my practice yesterday I found a bag of MPH sitting on the course

Kevin:



Me:

Regards,

Scott
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  #38  
Old 09-10-2014, 04:13 PM
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What engine is in your -8? I think Kevin's is the Parallel valve 409. Doesn't seem to be doing bad against the rest.
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  #39  
Old 09-11-2014, 06:37 AM
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Originally Posted by osxuser View Post
What engine is in your -8? I think Kevin's is the Parallel valve 409. Doesn't seem to be doing bad against the rest.
So how does Reno work anyway? If I read the rules correctly, the heat races sort the qualifiers into 3 finals (Bronze, Silver, and Gold).

Everybody gets to fly in 3 heats?

Is assignment to Bronze, Silver, or Gold is based on the fastest speed recorded by a racer in any heat?

This year there seems to be 33 qualifiers. Each of the three finals has a maximum of 9 racers, so all the heats eliminate the slowest 6?

Right now, none of the -8's are going as fast as Jason Rovey did last year, and all are close to elimination.
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Last edited by DanH : 09-11-2014 at 06:40 AM.
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  #40  
Old 09-11-2014, 06:34 PM
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You forgot a class.

Medallion

+2 on Jason
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