When FV first started were Fans shrouds & Generators required in the beginning. Did people just run them because that's how the cars did? Did anyone try running without fans and gens and get shot down?
Thanks for any historical insight, Rick
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When FV first started were Fans shrouds & Generators required in the beginning. Did people just run them because that's how the cars did? Did anyone try running without fans and gens and get shot down?
Thanks for any historical insight, Rick
I raced a FV in 1968. Back then we had to run the fan and generator. The trick then was to run a very small vee belt and grease it so is slipped. At some point we only had to run the fan housing. Now we only have to be able to fit the fan housing inside the body work. Some where in the evolution to today's rules we had basket handles which were just strips of metal that would cover the fan housing but let air pass through..That only took 20 to 30 years to evolve to to days rulesQuote:
Originally Posted by rickd
Thanks for the background. Was it required to run all the other sheet metal covering the cylinders?Quote:
Originally Posted by S Lathrop
No. I do remember that at some tracks, maybe Lime Rock, the FVs that ran the fan would have trouble with noise restrictions. The fans would really scream at high RPM. The trick then was to have the belt slip .Quote:
Originally Posted by rickd
To add to Steve's history lesson...
Early on you had to start the race with a functioning fan and belt... didn't mean you had to finish with one. ;)
Then at some point the generator was supposed to be "functional" as I remember. Because guys would gut the generator so that it was just a shaft running through the housing.
Different fans from different series of engines had different numbers of blades. And some realized they could remove a lot of the blades from the fans to cut down on drag and inertia.
There was a lot of trickery surrounding fans in the early days.
"There was a lot of trickery surrounding fans in the early days."
I don't recall the exact specifics, but there were at least two fans that I *think* were legal, one with fewer blades than the other. The amount of HP it took to turn a fan at higher RPM was quite high, thus the slipping fan belts that were on the verge of flying off. I cured the flying off part with an external guide that kept the belt from coming off and never had another problem.
As my friend that used to race FV noted some years ago when he came to a race and looked at my car: "Sure is a lot cleaner without all the fan stuff in there".
Speaking of trickery, I've seen references to tilting the engine. What is the advantage in doing this, and how many degrees tilt.Quote:
Originally Posted by Purple Frog
The Lazers have a tilted engine. It's about 10 degrees. The reason is to lower the center of gravity.Quote:
Originally Posted by rickd
The Z12 had the engine tilted. Ity had 2 effects, lower CG and it helped cooling some what. It also helped reduce the frontal area of the car. None of these features by them selves were a big deal but collectively they added up to a better car.
Didn't tilting have a negative effect on oil pump pick-up?Quote:
Originally Posted by S Lathrop
check out the Taylor Stewart FVs run in CASC events circa earlier seventies
"reduce the frontal area"Quote:
Originally Posted by S Lathrop
The down ward angle was calculated from the rear wheels. 10 degrees down moves the entire engine downward. The fan housing comes down with it. Remember that the axle center line of the rear wheels remained constant because that position was dictated by the camber angle that one ran the rear wheels at and that in turn was dependent on the tires. The fan housing is quite some distance from the axle center line.Quote:
Originally Posted by provamo
When the fans were first removed I seem to recall reliability problems until the head cooling was worked out..
Tilting the engine reduces CG? Really? What are the two heaviest pieces on the FV? The engine and tranny. So if you tilt one down the other goes up. So how is that making the CG lower?
This discussion will go on for ever just like those who think if they cross the scale just at minimum weight think they are faster. Really? Then how did Noble end up with 5 national championships being 70+lbs over weight?
Ed
What you say would be true if, the engine and transmission would balanced around the rear axle. But I I think that if you try to balance the engine and transmission at the rear axle center line, you will have to push down on the transmission with very significant force to keep the assembly level. So I stand by my analysis. Also take a look at the run offs record of the Zink Z12 starting with John Hogdal's second place. I will let race results do my talking.Quote:
Originally Posted by Ed Womer
Race results or driver performance have no place in a technical discussion. They introduce variables that can not be adjusted for.
1) Clearly scientific formulas prove that extra weight is bad for acceleration, braking and cornering performance.
2 Yes, when the engine is tilted downward the transaxle moved upward.
The CG is lowered because:
a) Only the transmission section of the transaxle actually moves. The differential just rotates around the axle centerline.
b) The transmission is much lighter than the engine and is 50% closer to the axle center line than the engine.
Brian
I'd like to ask again, didn't tilting the engine have negative effect on oil pick-op by the oil pump. It seems you'd have oil collecting at the front of the engine.Quote:
Originally Posted by S Lathrop
10 degrees isn't a big deal for the oil, and they had extended sumps with extended pickups... Besides which the oil would run back to the center because of the blinding acceleration forces.
How could I have missed that...I always wondered why fv's did 3rd gear wheels. ;)Quote:
Originally Posted by Purple Frog
IIRC, from reading, 10d seemed to be tough for the oil pickup. Perhaps it was the Aussie FV racing where I read this.
Oil sump extensions were allowed when we did it. Without the extensions, it might have been a struggle. We did find that we needed to run the oil level a bit above normal.Quote:
Originally Posted by BLS
"We did find that we needed to run the oil level a bit above normal."
I think everyone does that now. Back in the 70's I only ran over, by about 1/2 quart, at speedway tracks like Charlotte. When I started getting advice back around 2012 or so I was surprised to find that the higher level was always used.
I also wonder why some angle is not always used on newer designs Even if 10d is the limit for oil purposes, it seems anything up to that is pretty much a free gain with no real downside.
Typically, the biggest load on the FV oil system is just after long sweeping corners and just after hard braking zones. Obviously, a hard braking zone after several long corners (the same direction) are worst case scenario. The oil moves everywhere but into the sump pickup area. That is why FV engines have windage trays and baffles in the push rod tubes. Some people, myself included, would build more elaborate windage systems, particularly to keep the oil from sloshing forward under braking. Aside from oil supply concerns, having high levels of oil in the cam gear area is not good for power. The perfect system would reduce the initial sloshing, but not restrict the oil returning to the sump pickup. Quite the challenge! So, concerning all the oil moving around when on track, that 10 degree tilt was of minimal concern.Quote:
Originally Posted by rickd
Take note to Mr.Lathrop'd assessment. This past season I campaigned one of the first two Z-12's He and Ed Zink built. The engine is canted 10 degrees nose down. Installed is a 15 psi triggered dash light with an added 7psi ignition shut down. Run with 4 qts in the sump. The engine has a single windage plate running inline with the cam. Not a single op issue the entire 5 event season with VSCDA.And I beat hell out of the engine at the last Blackhawk Farms race and finished 3rd turning 1.27s. Turned a 1.26 in practice. Was in second place 7 times during the race.
The Z-12 is the most well thought out experiment that set the base design for all FV going forward. Though not an engineer I will add one observation. Dropping the center line 10 degrees is about relocating kinetic mass. Mass times angular velocity changes the game. Measure from axle center-line to shift shaft entry then the same to crank pulley. Now think about this. The difference of the two creates a weighted class one lever ratio. My guess is there exists close a 3.0 to 1 ratio in favor of engine. Drop that engine mass 10 degrees then calculate angular kinetic mass and my guess the math results favors Mr Lathrop's engineering.
Excellent build. Extremely predicable cornering. Fun to drive safe car. And it is a prototype. Impressive!
Well done Mr.Lathrop.
Cheers,
Dave