Formula Vee CFD???

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autogyro
64
Joined: Sun Oct 04, 2009 2:03 pm

Re: Formula Vee CFD???

Post by autogyro » Fri Apr 16, 2010 11:09 am

engineguru00 wrote:I am currently running CFD for GTR on the project and hopefully we will have some numbers/pictures in the next day or so. I did notice a few things when looking at the model though (alot easier when you can rotate it). The sidepod exits lie directly inline with the lower beams of the front axle, which could cause some issues cooling wise but my guess is the cooling system is over sized.

My time as an engine guy also gives me a few concerns on the ram air plenum that I saw. Be careful with the pressure distribution across the system as it runs on the track, its likely the rear cylinders will be drawing from much higher pressure than the fronts and this difference in pressure will change with track speed. Is this engine carbed or EFI? Nice thing about carbs is they self regulate in this case, where as EFI wont automatically unless you run a closed loop correction system on every cylinder individually.
That takes me back a way. Looks like the engine uses 45DCOE Webers or Delortos
Knife edge the butterflys and smooth out the venturis for better airflow, there is a couple of bhp there to be had. You might have problems on the air front to rear in the ram air plenum as mentioned. You should be able to get over it so long as it is not severe by changing the air correctors front to rear in the four barrels. It depends on the range of jetting for different tracks you have. For shorter tracks I would change to 48IDA Webers for a bit more bottom end torque. Downdraft though, so a different intake.
You could post your jetting if you like, would be interesting.

GTRdesign
2
Joined: Mon Oct 20, 2008 10:30 am
Location: Pretoria, South Africa

Re: Formula Vee CFD???

Post by GTRdesign » Fri Apr 16, 2010 11:39 am

I'm getting so excited! thanks for all the input guys!

The airbox in the CAD model was just for representation for the RP model, in practice we 'll use the airbox from my previous car and it's fairly well developed. Our carbs are regulated, so we all use twin 40 DCOE Webers with 34mm chokes and F9 emulsion tubes. I use 180-200 airs and 130-140 mains. Depends.

I like the idea of adjustable ballast a lot, and it's very implementable, also, to extend the splitter forward will be relatively easy too with an add on. I'm getting very worried about my drooped nose though, can't wait to see Enginerguru's CFD stuff. Luckily there is the option available for a different nose cone.
If you can't fix it with a hammer, it's probably electrical

engineguru00
0
Joined: Thu Mar 18, 2010 5:24 pm
Location: Buffalo,NY

Re: Formula Vee CFD???

Post by engineguru00 » Fri Apr 16, 2010 4:42 pm

Sounds good then. The CFD is taking a long time as there is an incredible amount of detail in some of the parts that are resulting in very high mesh densities. The wheels in particular are being tricky with all those little step changes. Only 31 million mesh elements needed according to CFDesign to run the program, so my computer is taking a while to mesh it.

Good to hear you have the intake manifold sorted. I have seen a few good cars be destroyed by a crippled intake manifold that robbed up to 20% top end power. Carbs may be "ancient technology", but they still have some advantages to EFI and the self regulation is part of that.
Chris
UB Motorsports: Formula SAE '08-'10
Powertrain Team Leader '08-'10
Captain '09-'10

RH1300S
1
Joined: Mon Jun 06, 2005 2:29 pm

Re: Formula Vee CFD???

Post by RH1300S » Fri Apr 16, 2010 5:05 pm

autogyro wrote:That takes me back a way. Looks like the engine uses 45DCOE Webers or Delortos
Knife edge the butterflys and smooth out the venturis for better airflow, there is a couple of bhp there to be had.
With apologies, can I hijack this thread for just one post?

autogyro - I have a pair of DCOE's on my Alpine. I know that you get different angled edges on the throttle plates (and I presume shape of plate) which affect the position they close at and how they interact with the progression holes. Is there a way to do this and keep the throttle plates closing at the correct angle?

autogyro
64
Joined: Sun Oct 04, 2009 2:03 pm

Re: Formula Vee CFD???

Post by autogyro » Fri Apr 16, 2010 7:13 pm

RH1300S wrote:
autogyro wrote:That takes me back a way. Looks like the engine uses 45DCOE Webers or Delortos
Knife edge the butterflys and smooth out the venturis for better airflow, there is a couple of bhp there to be had.
With apologies, can I hijack this thread for just one post?

autogyro - I have a pair of DCOE's on my Alpine. I know that you get different angled edges on the throttle plates (and I presume shape of plate) which affect the position they close at and how they interact with the progression holes. Is there a way to do this and keep the throttle plates closing at the correct angle?
Second try I lost the last post damn.

I only call them throttle plates on the TJ slide injection system as fitted to the TR6.

The 'throttle butterflys' in the 45DCOE in my hands stops between two holes in the carb body there is another hole further outboard. These holes bleed air around the BF to maintain airflow through the brass emulsion tube and idle jet for tick over.

I used to hand grind the BFs on a carborundum stone and finish with progresive emery paper.
Try not to flake the edges. When smooth fit to the spindle slot being careful not to allow the spindle spring to fly closed. Fit the two screws loosely and move and try the fit until the BF closes fully and does not stick. You can use a light paint or powder to visualy see better. Blow (with mouth) with throttle closed to get an idea of the bleed flow. Remove one screw and use locktite tighten and remove other screw do the same and for other barrel an other carb. File the srews to match the spindles and smooth.

If you remove the alloy emulsion tube in the barreL, you can clean up the edges and smooth the barrel, DO NOT take off any steps.

Always mount Webers with two rubber o rings one either side of a central grooved spacer and always mount flexibly using the through bolts and springs 10 ibs inches approx again with locktite.

To set float levels blow through the fuel pipe into the float needle valve and move the float closed, the flow should cease when the float lever is level with the flat surface of the cover. Bend lever to suit match both carbs exactly. Many problems are missed because the needle valve jet is to small for performance use. It should be increased in size for anything over about 120 main jets and 190 air corrects. Also the pump jets become more critical as power increases with tuning or cam changes causing an initial lag on fast apply throttle, increase pump jet size.

RH1300S
1
Joined: Mon Jun 06, 2005 2:29 pm

Re: Formula Vee CFD???

Post by RH1300S » Mon Apr 19, 2010 2:37 pm

Great info - thanks

autogyro
64
Joined: Sun Oct 04, 2009 2:03 pm

Re: Formula Vee CFD???

Post by autogyro » Tue Apr 20, 2010 1:01 pm

Sorry for that GTRDesign, I hope your thread will continue, it is an interesting car and there are many who use this site who I am sure will help you develop it.

marcush.
268
Joined: Tue Mar 09, 2004 3:55 pm

Re: Formula Vee CFD???

Post by marcush. » Tue Apr 20, 2010 1:24 pm

autogyro wrote:Sorry for that GTRDesign, I hope your thread will continue, it is an interesting car and there are many who use this site who I am sure will help you develop it.
very very much that is.the Formula Vee thing is much more interesting then I thought
in the past.

GTRdesign
2
Joined: Mon Oct 20, 2008 10:30 am
Location: Pretoria, South Africa

Re: Formula Vee CFD???

Post by GTRdesign » Thu Apr 22, 2010 8:17 am

No prob autogyro, the carbs are a big part of the Formula Vee and most of us have a bit of a love hate relationship with them.

I'm also running a set of 40's on my golf 1 against a field of fuel injection cars only, and when they work, they're magic!!!
If you can't fix it with a hammer, it's probably electrical

marcush.
268
Joined: Tue Mar 09, 2004 3:55 pm

Re: Formula Vee CFD???

Post by marcush. » Thu Apr 22, 2010 8:38 am

one question surounding the type1 front suspension carrier:

I can follow the aim to raise the tub to get unrestricted flow between the tyres near ground level ,no question about that.

But between the two tubes ,do what you want ,this will always be an area you will have restrictions .those tubes are quite big in crossection and the space between them is not very much .as you need an air inlet for the watercooling anyways would´nt the space between those two tubes not be ideally suited for this purpose?
It would as well open the oportunity to move the radiators a bit forward as well
the idea is to let the whole sidepod shadow the front suspension member to reduce crossection of the car.

GTRdesign
2
Joined: Mon Oct 20, 2008 10:30 am
Location: Pretoria, South Africa

Re: Formula Vee CFD???

Post by GTRdesign » Tue Apr 27, 2010 10:21 am

Interesting idea marcush, the concern with that would be the height of the radiator mass, unless I mount them lower and back with some longer ducting, unfortunately that would also increase the cross sectoinal area betwean the front wheels.
If you can't fix it with a hammer, it's probably electrical

marcush.
268
Joined: Tue Mar 09, 2004 3:55 pm

Re: Formula Vee CFD???

Post by marcush. » Tue Apr 27, 2010 10:41 am

GTRdesign wrote:Interesting idea marcush, the concern with that would be the height of the radiator mass, unless I mount them lower and back with some longer ducting, unfortunately that would also increase the cross sectoinal area betwean the front wheels.

i remember the piece from Simon mcbeath in Racecar engineering ,where they tried to
shroud the tubes and did not find a ways to reduce drag do what they could.

their conclusion back then was that the obstruction of the beam was leading to convergence between the front tyres and the two tubes were effectively too close together to avoid this happenning .So if this is the case ..then you could as well use the obstruction to have a purpose as well and design .
I understand the drawback of raising the radiator,but the question would be if that was really such a big impact for CG height .it surely depends how you are angling the rad core or maybe it was possible to lay it even flat ,reducing crossection even more...

weedkiller
0
Joined: Mon Dec 06, 2010 8:50 pm
Location: Cape Town South Africa

Re: Formula Vee CFD???

Post by weedkiller » Mon Dec 06, 2010 9:21 pm

Hi

We are also building a Vee (South Africa). This was a very informative.

We designed a 'prototype' to gain experience and test concepts. Will start with the 'real' car over December to be raced 2011 season.

PS: GTRdesign, please contact me via aeonracing(point)co(point)za

A

GTRdesign
2
Joined: Mon Oct 20, 2008 10:30 am
Location: Pretoria, South Africa

Re: Formula Vee CFD???

Post by GTRdesign » Tue May 31, 2016 9:15 pm

Few years later, the car actually got built, here are a few pics.

Image

Image

Image

It's a good car, with good performance, consistently topping the speed traps. Just needs a better driver :wtf:

Thanks for all the input guys!

(hope my image links work, they're from facebook)
If you can't fix it with a hammer, it's probably electrical

bill shoe
165
Joined: Wed Nov 19, 2008 7:18 am
Location: Dallas, Texas, USA

Re: Formula Vee CFD???

Post by bill shoe » Wed Jun 01, 2016 1:18 am

That's a sweet looking car! By far the most interesting FV I've seen. Congrats on turning it into running reality, and thanks for bringing this thread back to life after 6 years!! Is 6 years a record for a legitimate, functional thread update? =D> =D> =D> =D> =D>