GP-5 qualifies at 363 mph!

[kenf]

Re: GP-5 qualifies at 363 mph!

"I can't help but wonder, had George's girl been allowed to compete in unlimited class, what the engine of choice would have been..."



I remember a few years ago there was a bumper sticker on the wall by the room wher ethey held the pilot's meetings that showed the the GP-5 as an unlimited racer. It indicated that the power would be a Chevy V8 and the name would be "Heartbeat".

[Arctic Cat]

Re: GP-5 qualifies at 363 mph!

Judging by the tight fit of the engine compartment, I would guess that it was designed from the beginning around the small block Chevy. From the article, it would appear that they are looking to add some way to boost power to make up for high/ density altitude power loss. Will have to be a blower or nitrous, as I don't see them having room for all the plumbing for a turbo set up.

[C_roundy]

Re: GP-5 qualifies at 363 mph!

Judging by the tight fit of the engine compartment, I would guess that it was designed from the beginning around the small block Chevy. From the article, it would appear that they are looking to add some way to boost power to make up for high/ density altitude power loss. Will have to be a blower or nitrous, as I don't see them having room for all the plumbing for a turbo set up.

I agree with all of that, I am curious about the specific setup that George Pereira had in mind for said Chevy, to deliver the high continuous power settings he designed his airplane to withstand.

Even if more modern parts can better replace what he had in mind at the time, it would still be a nice little historic outake to learn his thoughts at the time...

[georgiacub]

Re: GP-5 qualifies at 363 mph!

"However, the mean airport elevation at Reno-Stead is 5050 ft. above sea level. On a day at Reno with an OAT of 85°F and standard pressure of 24.44 in-hg (29.92 altimeter setting), the density altitiude is 8350 feet and the density ratio is 0.78. Therefore, under those conditions, the engine in Sweet Dreams is capable of approximately 500 hp max."

The above quote from the article failed to mention that Andy Chiavetta added a ram air scoop on the GP5 for Lee that added back 2" of manifold pressure. This is a 40% recovery or 50 horse power.

Lee is a very determined person and has been able to get a lot of speed from his normally aspired Legacy. The GP5 does not have a lot of unused space where he could install nitrous oxide bottles that would take him through the entire race.

There are problems with trying to install a supercharger. I don't think there is space inside the current cowling and would require "bumps" on the cowling for an installiation. This is not a big deal as wittness the "bumps" on the Super Legacys of Darryl Greenamyer and Lynn Farnsworth that provide space for the intercoolers for their turbochargers. The most challenging problem would be supercharging a high compression engine and not being destroyed by detonation. Two Thunder Mustangs that installed superchargers dealt with this problem with limited sucess. Jon Parker was running with nitrous oxide this year rather than continue to deal with the supercharger problems.

High gearbox temperatures are another issue that will require a soultion.

Just some thoughts on the GP5, as it exists today, from my observation. With enough money and effort Lee may come up with viable solutions to all of these challenges.

[RpR]

Re: GP-5 qualifies at 363 mph!

Gentlemen:
I have been reading this site for years but this thread has me wondering enough to actually post.

The small-block Chevy in this aircraft at 650 hp, at sea level, is not a truly high horsepower engine.
Obviously this is an aircraft and not a car so a direct comparison is faulty but as small block Chevies, of lessor displacement can easily produce well over seven hundred to eight hundred horse-power, what requirement of an aircraft that a car does not have would prevent the owner from using an engine with higher horsepower?

Both the Mouse and LS small-blocks have after-market blocks that can exceed five hundred inches cubed, would this not be a better engine, at least on paper?

A few aircraft like these might breath new life into Reno.

[Tibia]

Re: GP-5 qualifies at 363 mph!

...what requirement of an aircraft that a car does not have would prevent the owner from using an engine with higher horsepower?

Reliability while running sustained high power.

[RpR]

Re: GP-5 qualifies at 363 mph!

Reliability while running sustained high power.

OK, that said, NASCAR small blocks run at very high speeds for five hundred miles with good reliability.
Now I am speaking of air race engines not adapting one for civilian use which is different, so for the short duration of the Reno races one would think that the engine would not be subject to any more strain than one used on the ovals where the engines go up and down from six thousand to nine thousand range for five hundred miles.

They would like to put some form of blower on the engine which would seem, it has on road race cars, to put more strain than simply using a carb. or injected higher horsepower level, or simply more inches for higher horsepower with less effort.
It seems the Pond Racers greatest failing was heat due to poor cowling design while at the same time using blown engines stressed to max levels with really no safety margin with semi-predictable results. (Not the crash)

Do the aero engines hit a certain rpm and have to hold it for the entire race or go up and down like an oval engine?
What rpm does this small block turn during the race?

What other stresses do the aero engine get that auto engines do not get?

At Daytona and Talledega the small block engines are stressed to extremes as they are subject to longer times at nine thousand plus rpm while drinking through a soda straw, so just high rpm would not seem to be the only item.

[Speed Quest]

Re: GP-5 qualifies at 363 mph!

The limits imposed are on the prop speed more than on the engine. In the 350 mph and higher speed, it is usually best to keep the prop speed at or below 3000 rpm to prevent the tips from reaching the supersonic range. Most likely, the slower the prop turns, the more efficient it is at turning torque/horsepower into forward speed.
If anyone can fly the GP-5 into the 400 mph range around the course, Lee Behel can.
Great job, Good luck next year.

[51fixer]

Re: GP-5 qualifies at 363 mph!

They would like to put some form of blower on the engine which would seem, it has on road race cars, to put more strain than simply using a carb. or injected higher horsepower level, or simply more inches for higher horsepower with less effort.

Whether you put a blower or Turbo you may have to redesign the engine as compression ratio, pistons and structure components will change. Also will the nosecase setup for the HP this version puts out be able to handle the higher power of the upgraded engine?

It seems the Pond Racers greatest failing was heat due to poor cowling design while at the same time using blown engines stressed to max levels with really no safety margin with semi-predictable results. (Not the crash)

Cowling design and heat were not the issues with the Pond Racer. I've only had 1 beer and I'll try to remember some of that time.
Lessons to take away from that from my view is- Know your limits of time in an emergency. Almost all Unlimited emergencies have happened and what the A/C will do in these situations has a good database.
You start with something new always give yourself a way to get on a runway in a minute or less. You don't know what will happen. Upwind, downwind or crosswind you land.
Pond Engine builder was very surprised at the damage when his engine 1st threw a rod. He didn't take in the fact the prop will still drive the engine. On a race car you push in the clutch and pull over after a rod lets loose. He didn't expect multiple rods breaking.
Keep it simple- PR had extra components as a system designed by the engine builder. He never got it running right and after Steve Hinton took it over most of the gremlins as far as operation got made to operate reliably to a degree.
Pay attention to human factors- Decision making needs purposeful goals and limits.

Do the aero engines hit a certain rpm and have to hold it for the entire race or go up and down like an oval engine?
What rpm does this small block turn during the race?

You run a constant power setting. You adjust power with the throttle and RPM with the prop.

What other stresses do the aero engine get that auto engines do not get?

Some differences in G loading, density changes the fuel system has to compensate for, cruise power settings typically 60-75% of full power so that an aero engine has to be able to run at 3/4 throttle all day long.

[AAFO_WSagar]

Re: GP-5 qualifies at 363 mph!

Fixer... can't tell you how much your commentary is valued! Please, keep digging into your toolbag with your posts!

[MRE]

Re: GP-5 qualifies at 363 mph!

Since they don't have room for turbo's maybe they could run an sb2 small block chevy. Used to be the engine they ran in cup. Very common in road racing chevys in trans am and club racing. Bigger and better breathing cylinder heads, good for 800 plus horsepower. probably would have to bump out the cowling, then there's the nose case.

[Arctic Cat]

Re: GP-5 qualifies at 363 mph!

the new zr1 vette motor is pretty slick. It was designed for tight spaces, in the design process they were not allowed to change the angle of the hood so the blower fits under a stock vette hood. 680hp with a 100k mile warranty on the car.

[440_Magnum]

Re: GP-5 qualifies at 363 mph!

RpR- I personally don't think a "NASCAR-like" engine would last one lap at Reno. The environment is just too different. Aero engines have to tolerate different G-loadings (including brief negative without losing oil pressure). They have to have gearboxes that can withstand the harmonics of engine firing pulses, propeller blade rate pulses, and gear-tooth rate pulses. At certain RPMs, the harmonics and resonances can be destructive, so careful planning and design is required. Aero engines have to be COMPACT. They can't have high-rise intakes, bulky exhaust manifolds, belt-driven scavenge pumps are big and also a failure point, ignition wires have to be altitude tolerant or pressurized, etc. etc.


This is just my opinion, and I wouldn't presume to give advice to the GP-5 team at all. I justthink what the GP-5 team has done is tremendously impressive, and to go faster they should probably KEEP thinking 'airplane' and fervently resist the temptation to look toward NASCAR or other automobile racing environments, except for specific parts. The advent of the LS-series GM (not 'Chevy,' its now truly corporate) engine is huge, because its so much lighter and more reliable than the old boat-anchor of a smallblock Chevy v8 that is still sorta the foundation of the 'Chevy' NASCAR engine... and that might be a better foundation for an aero engine, although what they're doing is really so good that again I wouldn't presume to give advice. Truth be told, the NASCAR engine of any brand is now practically a spec engine, containing features of Dodge, Ford, and Chevy racing engines from the past decade... as is obvious by the front-mounted distributor on 'Dodge' and 'Chevy' NASCAR engines, as well as the even-spaced exhaust ports- both characterstics of FORD small-blocks! The 'Toyota' NASCAR engine has nothing in common with any Toyota engine ever produced for sale to the public, so in some ways it was the first 'spec' NASCAR engine.

And I say all this as an avid auto enthusiast... my point is that while basic engine may be able to go either air racing or road racing, but the go-fast modifications for each are VERY different and what works for the road may not translate over at all. Heck, if it was an easy leap to make, Jack Roush would have already done it- being the NASCAR owner and aviation buff that he is.

[RpR]

Re: GP-5 qualifies at 363 mph!

I did not say a tuned for NASCAR racing engine should be used, I said that the strees a NASCAR V-8 endures is at least equal to one that would be used at Reno.

The current NASCAR engines are not "spec." but purpose built push-rod competition engines, that except for the ferrous alloy blocks would probably work well in the GP5.

The small block Chevy will always be a small block Chevy especially as the new one that replaces the LS is called the new Small-block.
Exhaust port spacing and distributor location is a point of funtion purpose.
There have been even spaced heads on engines other than Fords, and ditto for the valve spacing that that cause the port locations some seem to think belong to the small-block Chevy.

You are correct most any engine can be made work in an aircraft if one truly wants it to happen.
I just wanted to know what stresses air racing put on an engine that would affect the possibility of using an automobile engine.

I have studied auto mechanics and owned part of and worked on a dirt track stock car, long ago, so I have more than average knowledge of how automobiles function.
Now aeroplanes-- I know more about aerodynamics than I do what makes an aircraft engine function properly.
The closest I got to that was when they quit making lead auto gasoline, I would drive out to the airport and fill-up my Boss Mustang with aviation gasoline.

As an aside, in auto-mechanics we were given parts and told - this is a small block Chevy, assemble it.
My partner and I did that, but we could not get it to run or even attempt to run without a major back-fire.
There were three instructors. We had two of them looking at it totally mystified as to what was wrong.
The third walked in so they called him over ( he was an old school hot-rodder and would rip you a new butt-hole if he saw you put lug-nuts on with an air-wrench.)
He walked over, looked at it for very short time and said "You have the spark-plug wire order reverserd."