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We just got these dyno numbers in from Sam-Tech in Houston.
Here it is, what we have all been waiting for. The LS376/480 first run baseline dyno data.
I can't post the graph, but the numbers are:
3500 rpm - 275hp 430 lb ft
4000 rpm - 350hp 460 lb ft
4500 rpm - 430hp 480 lb ft
5000 rpm - 475hp 490 lb ft
This was with long tube headers. The dyno shop is warning us to expect up to a 100hp loss when the P-51 Mustang style "short stack" exhaust is bolted on.
Max hp registered 525 at 6000 rpm. We are limited to 4500 max.
Next dyno run will be with our "short stack" exhaust manifold. A simple pipe coming off each cylinder exhaust port, about 12 inches long with a 45 degree bend in the middle.
How much of a power loss should we expect with this setup? I have read other dyno reports that show about a 6% loss.
So many factors when it comes to performance in aviation engines. What fuel was that on? 100 octane AV? Can we get more info about the motor? Why are you limited to 4500 rpm? The short exhaust pipes will favor higher RPM. Why are there 6 primaries if its a V8? Definitely need to have a more in depth conversation.
So many factors when it comes to performance in aviation engines. What fuel was that on? 100 octane AV? Can we get more info about the motor? Why are you limited to 4500 rpm? The short exhaust pipes will favor higher RPM. Why are there 6 primaries if its a V8? Definitely need to have a more in depth conversation.
The engine is an LS376-495 GM Crate Engine. On the dyno at Hutter Performance, in Chardon Ohio, it showed over 525 hp. The torque numbers were crazy also.
The main fuel will be 93UL. When on a cross country flight, we will burn 100LL Avgas. The engine is tuned to default for 93UL. So when burning Avgas the mixture will be slightly more rich.
The exhaust stack is new, with larger diameter pipes, and just a bit longer in length. We were able to get back some of the lost power by redesigning the exhaust.
There are 6 pipes on each side, but only 4 are functional. The Merlin powered P-51 engine is a V12, so we wanted the plane to look correct.
The PSRU (Gearbox / Prop Speed Reduction Unit) is rated for 600 hp. But the max continuous rpm for it is 4500. So that is a hard limit for us. We will still have 420 hp at that setting.
With all that said, are you looking to make more power with it? If so, there are numerous things that can be done to shift the power band down. Different cam comes to mind almost immediately, along with a...wait...what computer is doing the engine management functions?
EDIT: Any pictures of the induction setup for the motor? How is it getting it's air and throttle control? Also, any pics of the oil pan setup? Curious how it will get oil if inverted?
Last edited by Pb82 Ronin; 03-09-2021 at 01:57 PM.
With all that said, are you looking to make more power with it? If so, there are numerous things that can be done to shift the power band down. Different cam comes to mind almost immediately, along with a...wait...what computer is doing the engine management functions?
EDIT: Any pictures of the induction setup for the motor? How is it getting it's air and throttle control?
The photo of the top of the engine shows the large air filter, sitting right on top. The ECU is a MoTeC, the absolute best for this application. This engine has the GM Factory "Hot Cam" option. If I could do it over, Hutter Performance would have got a custom cam for us, with the torque band lower. But we have gobs of power as is.
Just get flying for now. I have a professional test pilot to work with me initially. Then my plan is to simply enjoy the Mustang! Probably do some air shows with it.
Here is a photo from the Hutter Performance Shop, the people who did my engine tuning and custom built my exhaust. These guys are the best! True LS experts!
I wonder if anyone has installed a supercharger when building this kit ?
I am thinking that with adding a supercharger, you could not get an Airworthiness Certificate for it ... A supercharger would certainly increase the service ceiling, but then require you to install supplemental oxygen.
I am thinking that 4-blade prop cost a pretty penny (to say the least) !
Neat project!! Are you limited RPM wise by prop tip speed (below speed of sound) ? Is the prop direct drive or does it have a gear box? I remember the Mooney 201 with the Porsche air cooled horizontally opposed 6 cylinder. It had a gear box where the engine could run up to where it made good power while keeping the prop speed reasonably. That was wet dream stuff when I was still flying...
I wonder if anyone has installed a supercharger when building this kit ?
I am thinking that with adding a supercharger, you could not get an Airworthiness Certificate for it ... A supercharger would certainly increase the service ceiling, but then require you to install supplemental oxygen.
I am thinking that 4-blade prop cost a pretty penny (to say the least) !
The Mustang factory has a super-charger option, but that is for the V6 Honda 3.5. The weight penalty for my LS3 was too much. Yes, those big paddle-props are a bit pricey. Plus we waited over three years to get mine. It is #2 off the production line, Whirlwind Aviation. And you think the wait is long for a C8!
The landing gear is electrically controlled (with a computer), and hydraulically operated.
Neat project!! Are you limited RPM wise by prop tip speed (below speed of sound) ? Is the prop direct drive or does it have a gear box? I remember the Mooney 201 with the Porsche air cooled horizontally opposed 6 cylinder. It had a gear box where the engine could run up to where it made good power while keeping the prop speed reasonably. That was wet dream stuff when I was still flying...
The limit is for the propeller gearbox. It's ratio is 2.21-1. The prop will never go over 2036 rpm with the engine at 4500.
The sweet spot for best cruise is having the prop tip speeds right at Mach .65, with the speed of sound at 770 mph.
The plane's service ceiling is over FL200 (20,000 feet).
If I ever won the lottery, I would love to own that same completed kit ... but I don't have any tail dragger time. I would more than likely ground loop the thing first time attempting a landing.
Well, I do have some tail dragger time, but in the wrong type of aircraft .
If I ever won the lottery, I would love to own that same completed kit ... but I don't have any tail dragger time. I would more than likely ground loop the thing first time attempting a landing.
Well, I do have some tail dragger time, but in the wrong type of aircraft .
That's way cool! I just got recertified in tailwheel aircraft last summer, in a Super Decathlon.
10-15-2017, 11:19 AM
Dyno numbers LS376/480
