Newbie questions

[southysuper]

[FONT=Verdana]I see that many cars are running without a cooling fan\shroud. Many more are without an alternator or generator. I saw one recently running a pulley and shaft to bypass the alt\gen to turn a small fan in a custom shroud. I could not ask the driver\owner so I’m asking here. I guess most drivers opt to run without the fan due to the confines of the body work and\or the power loss? So I guess the benefit of the cooling outweigh the benefit of the alt\gen? Does anyone know the HP loss number for an alt\gen with fan, just fan, just alt\gen? I cannot seem to fnd these answers in this forum and I even asked the guys at aircooled technology thinking they may have tested this in making their DTM cooling systems.[/FONT]

[provamo]

to what class, what application are you referring

[southysuper]

I have a citation minus front beam that I'm hoping to convert to FST. I was hoping this forum would help some with some of my questions? Perhaps not.

[Bill Bonow]

Bill,

I think the confusion (on our part) came from the fan issue. The only cars I see that run a fan (and/or generator) is the monoposto vintage FV guys. From our general findings ("our" being the FST guys here in the midwest), is that a fan is not required to keep the heads cool at speed. Most of us see head temps in the 300 F range with oil temps around 200 F. A fan is just not needed for road racing.

The HP loss with a fan is RPM conditional. With a stock crank pulley the fan to crank ratio is 2:1 (i.e. the crank at 6000 PRM, the fan at 12,000 RPM). This always kept FV engines rev limited as around 6000 RPM crank speed, the fan is at stall and will drain 6 to 8 HP (depending on the fan type) killing top end (or any hopes of seeing higher than 6000 RPM). Early on, I built a crank pulley that kept the ratio at 1:1 putting the fan speed into its designed speed range (Beetle crusing along at 3000 rpm highway speed). The thinking was no ducting hanging in the breeze. In the end, removing all that tin was the best plan.

If your thinking of converting a Citation, a fan will not fit without changing the rear roll bar bracing. Garry Sharp of Atlanta has a converted Citation. He would be a good resource for any questions. He runs down in SE division on a regular basis.

Here is a couple photos of Garry's Ride. Note: I think this is old/changed as Garry was mounting a Silver Bullet body over the winter.

[southysuper]

Bill,
Thank you for the info. I did not think about the rear roll bar. Ever thought about an electric fan with custom tins? Like a small squirrel fan centered over the cylinders? Thanks.
Bill

[Bill Bonow]

Ever thought about an electric fan with custom tins? Like a small squirrel fan centered over the cylinders?

Many solo FV guys have electric fans just as you describe to cool down between runs as they never get up to road racing type speeds and allow for fan-less cooling. However, the solo cars are completely different from road race cars.

A more direct answer is no I haven't thought about an electric fan, we don't need it to keep cool

[gbmetcalf]

I have seen a few different cooling systems in the solo ranks, depending on the location ie(the south vs the north) cooling may be just a between runs issue. I have also seen a squirl fan used but it seemed like a lot of weight and bother for a 1 min. run.
In the FV and FST ranks cooling is done by ducting air over the cylinders and heads.

G.

[jsteeb]

SS... Don't take the silence as all of us blowing you off. A lot of us were at Nelson this weekend, and don't have the energy left to check Apex at the end of the day.

Bill pretty much summed it up tho. Nobody in FST is running a cooling fan. The guys across the pond to the west seem to be,but here in North America, we all run cooling scoops of some sort.

I've thought about trying to fit an electric fan in, but... once you package the oil tank, airbox, electrical stuff, throttle linkage, and all of the plumbing...there just isn't a lot of room left. Maybe longer cars have an advantage over me there.

The one decision you really need to make is whether or not you want to use what I call, "top down" scoops, or "side in" scoops. Top down scoops tend to use the stock tins and bring the air in parallel to the fins. Side in scoops usually have custom tins (see the Mission Racing web site for pics of the best side in scoops I've seen). These bring the air in perpendicular to the fins, and then turn it down through the bottom.

I use side-ins too, but I need to improve them. My head temps have been in the 400deg range. Too hot for me.

Hey Bill....where do you measure your head temps? #3 spark plug? I think I remember reading that you measure it in a different location?

[Diamond Level Motorsports]

I have raced a FST with a fan on it. (see picture below) The fan provided me a easy solution to cool the engine as I was short on time to get to the track. I can tell you though that the fan takes several HP at the higher RPM's and temps were still 500 Deg.F under the plug.

A properly made air scoop is the answer, however, I have never been able to buy, or make, one that I thought was adequate.

I have seriously considered running electric fans, however, they would have to be massive squirrel cage fans to meet the CFM Vs static pressure requirements do the job. Additionally, you would then need quite a large battery to power them. Find a good aerodynamics guy and build your own air scoops. BTW, I think ducting the air from a position above the engine into the stock cylinder tins is the best way. Or as Jason said, top down scoops. I would like to see no more then 350 deg. F measured under the plug. Of course, I have never seen anywhere near that. Even my FV runs 450 under the plug.

I have hundreds of FV and FST build pictures in my photobucket account if you are looking for ideas.

http://s138.photobucket.com/albums/q...Mystique%20M5/

[provamo]

Diamond are you not drawing your cooling air through your oil "cooler"....seems that you are pre-heating your heads.................i may be entirely wrong since i have not sat in Vee in decades

[Bill Bonow]

Hey Bill....where do you measure your head temps? #3 spark plug? I think I remember reading that you measure it in a different location?

I hate the under the plug location. Although it is probably the highest temp point, I've seen too many lost spark plug threads. Most of the local fst guys all agreed to use the same temp point to give us good comparisons. Under the upper/inner # 3 head stud. On a hot/humid day, ranges from 275 to 325 F. I'm sure that under the spark plug it would be much warmer.

[Diamond Level Motorsports]

Diamond are you not drawing your cooling air through your oil "cooler"....seems that you are pre-heating your heads.................i may be entirely wrong since i have not sat in Vee in decades

Yes, you are correct. But I needed a way to cool the oil also so........... everything in racing is a compromise. Especially with the time line that I was on to get the car finished.

[Bill Bonow]

Bill,

Here are two photos of the purpose built scoops made by Jim Nash (Mission Race Cars) that Jason described in a earlier post. These are very nice/tidy scoops that I'd bet will fit many a conversion car without much fuss. As I understand, Jim is seeing similar temps as described above.

[lawyerbob]

SS - I know your post has to do with cooling specifically and everyone else has pretty much addressed that. But I noticed you are converting a Citation to FST.

I just completed my Citation conversion. Send me an e-mail (bob at graybeardracer.com) and I will send you some pics of what I did for an oil cooler mount and my scoops.

what year is your Citation? On my car mounting the beam meant some body mods, but others have not had to do that - I think it has to do with the very front of the chassis and the FV beam mounting structure.

Are you using the Bell Crank steering or are you modifying to a traditional tie-rod system mounted laterally in the car? If the later I can send you pics of mine.

Here is one of miine from this weekend at Nelson



Bob

[southysuper]

My car is a 93 and I do not have the nose piece, but I know I'll have to hack one up to fit the ball joint beam. I'm planning on some body mods, but what do you expect for an $800 car!

My car has an odd rack which looks like one made for an offorad buggy. The tie rods are almost prefectly parallel to where the beam would sit, but I know this rack is wrong for handling and felt like a "center load" type, but still subject to nasty bumpsteer.

Thank you all for the input on the cooling fan idea. I like those scoops shown above. I may even match the profile of the head hoop for the carb scoop.