94 Van Diemen
HPD '99 VD conversion kit just ordered for my RF94 2.0, now it's real!
Thanks to Apexspeed and it's members I have found most all the info I think I need to know to get this done.
One area of discussion has been the front upper engine mount. The question is how stiff should it be? Very solid, stressing the engine, somewhat flexy to not stress the fit engine?
Eric,
Have you contacted Keith?
http://www.apexspeed.com/forums/showthread.php?t=52309
Keith and Graham have now done two conversions from 94 VD FC.
Greg Rice, RICERACEPREP.com
F1600 Arrive-N-Drive for FRP and SCCA, FC SCCA also. Including Runoffs
2020 & 2022 F1600 Champion, 2020 SCCA FF Champion, 2021 SCCA FC Champion,
2016 F2000 Champion, Follow RiceRacePrep on Instagram.
Keith contacted me! He saw I was selling off the FC parts to makevoom for the it and offered help/info as needed.
His top front mount looks to be a "softer" version, long & bent tubes to original VD bracket on chassis. I've seen others that are short/straight/triangulated that would seem to be very stiff.
Starting this thread I was hoping for some insight into the how/why people have built them in different ways (before I start welding!)
Why choose soft other than to limit adding weight?
I posed the problem to a group of students at the local engineering school as a senior design project. It was fun for them, and a good way for me to get some insight into what the chassis might be doing. They did models of the frame around the engine and its ability to constrain the engine/trans assy in 6DOF. I had them treat the front half of the car as one rigid body and the engine/bell/transaxle as another rigid body. They then did hand calculations as well as FEA to see which degrees of freedom were the weakest, IE. most elastic. We also did the problem as a modal vibration model in FEA. The most flexible mode was established and we ended up making a much more rigid top mount to get about 2% increase in that minimum vibration frequency. This winter I have to light weight the truss. It got a bit heavy on us.
Now for a reality check. There is at least one modern chassis that seems to be quite flexible in the degree of freedom affected by the top mount and those cars are able to run up front. Go figure. Maybe you don't need stiffness beyond some amount.? Diminishing returns? I have given this some thought and still cannot see a clear reason why you wouldn't go for an infinite stiff assembly if you could get it for free and then have the tires and springs be the only flexible elements. Think of it in terms of a controls problem. The higher the minimum natural frequency of the plant you are controlling, the stiffer a control bandwidth you can apply without running into phase issues, which in turn results in a smaller control error.
The same reasoning that justifies pushrod/pullrod designs over rockers.
I will see if the school put the paper up on some public link somewhere
Here are two videos that I made to communicate the challenge to the students
https://www.youtube.com/watch?v=jg9OQtP4JV4
https://www.youtube.com/watch?v=eVKM1vEGZ9c
Long winded, horrible production ....
Steve
Last edited by Roux; 01.04.14 at 10:10 AM.
Video did a fine job conveying what you were looking for. Conclusions in paper would be interesting.
My aerospace engineering student son did some FEA analysis of the chassis strength loss from removing the VD "tripod" over the engine. None of the chassis mods we plugged into Solidworks yielded a chassis as stiff as the original design.
Turning my car into a flexi-flyer by removing the tripod got me to thinking how much load can be transferred throught the Fit block without causing issues for the engine. From a chassis standpoint I want to make a very rigid mount. Stressing a block that wasn't designed to be stressed makes me nervous...
More insights
I used the VD Engine to tank adapter piece as well as a custom piece below that to allow me to remove the Van Diemen frame under the engine and have something similar to the Swifts where the engine takes a lot of the load. There is no bottom frame going back to the bellhousing on those cars or on mine. My chassis started as a Formula Renault, and nothing behind the driver is original. I swapped the Renault tank for an RF94 model, reworked all the tubes and the Roll structure. I bring this up just so that you are aware that your car will be different in a number of ways
Steve
Infinite stiffness for free requires a significant donation of Unobtanium A. In the absence of that, increasing stiffness usually involves additional weight. Given that consideration, there is indeed a point of diminishing returns, but determining that point requires a relatively easy judgment call.Originally Posted by Roux
Every Formula SAE frame engineering student has to determine the relevant parameters that drive the judgment call, calculate the full range of those parameters, graph them, make that judgment call, then optimize the stiffness to weight ratio of the frame while holding that design target constant. Here is how most engineering students on the sharp end of the spectrum do it:
http://tinyurl.com/lj7qa5s
What about the other degrees of freedom?
Neil, I am familiar with that thread and all of the cheese references.
I was more interested in identifying which of the six degrees of freedom related to just that part of my car, the interface between the engine/tank/gearbox assy, had the lowest natural frequency. (or lowest stiffness). Since I was not designing a chassis from scratch , just reworking the way the rear of the car attaches. The original poster is working on the same challenge, since he has an existing car, but he has swapped engines and with that has come questions about how strong to make the upper front mount.
Steve
When I was at Ford Racing we did a study to determine which of the 6 DOF were most important. We determined that torsional and lateral bending were the most important to vehicle dynamics. For what that is worth.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
B.C.'s
In re assuming the front half of the car rigid, it is always worth thinking a little about the boundary conditions applied, whether for solids or CFD. What happens if the front half is not completely rigid? May be irrelevant, but worth thinking about.
- Frank C
In any FEA analysis, boundary conditions are EVERYTHING.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
All good discussion...
But I'm beginning to think engineers are like women. You ask a simple question and it turns into a big discussion!
Off to search for '99+ VD Fit install pictures.
Make it stiffer, you cannot go wrong with that direction unless you make the car really heavy. Make the engine a structural member. I doubt very much that if you do that that you will over stress the motor.All good discussion...
But I'm beginning to think engineers are like women. You ask a simple question and it turns into a big discussion!
Off to search for '99+ VD Fit install pictures.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
My experience with Toyota Atlantic engines was the exact opposite. Head gaskets were the victims of loading engines in ways that they were not designed for. Nazareth 1998 was a debacle in nearly every way possible.
Stress the oil pan.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
It appears the '99 chassis wouldn't hold itself up without the engine taking much of the load. Two parallel tubes, no triangulation, no tubes over the top/to roll hoop. Pictures at http://www.apexspeed.com/forums/showthread.php?t=55733
Eric,
How is the project going?
Mark
1990 Van Diemen, the Racing Machine, CM AutoX, 2016 Frontier
You can try to make a street car into an autocrosser or you can do a lot less work and make a race car into a great autocrosser
Chassis is cut up enough to fit engine in, engine is in place. Later in the week I hope to get the front motor mounts fabbed and chassis back together.
Gears on their way, wheels somewhere between Italy-New York-here, input shaft coming from England on the 16th.
Fuel cell, throttle cable, slave/throw out bearing, and dash are all in hand ready to go. Hall closet full of fresh Hoosiers.
Great report, Eric. Is your car one of the single front shock units? Do you know the wheel base length?
Mark
1990 Van Diemen, the Racing Machine, CM AutoX, 2016 Frontier
You can try to make a street car into an autocrosser or you can do a lot less work and make a race car into a great autocrosser
I think this car has been converted more than raced. Started out as a FC, swapped to FF and back to FC. Now going FFit.
Dual shock, 96ish" wheelbase. Car LOOKs much bigger than Mondiale but measures very similar. After fit conversion is done I'll scale it to see how the balance compares.
I finally got some garage time in.
Integral first, Autocross appropriate gears and correct input shaft I stalled. Tilton slave and mounting adapter in place. (hint of the day: connecting oil pressure gauge to slave doesn't work very well)
Chassis all welded/brazed and painted to accept Honda. Back half of car reinstalled.
Water and oil lines next.
I hope you find even more garage time. We're getting tired of running alone!
Oil lines in, AN fittings available locally
Silicone fittings/aluminum tube ordered. Back to working on other stuff.
Knock sensor is not used in our application?
I only need to tee oil pressure sensor & switch if I want a redundant (seperate from Aim dash) low oil light?
Brought car out to AAA today, ran it for the first time.
Knock sensor was home on the workbench, apparently not needed. You only need original oil pressure switch if you want the ECU to turn on a low oil pressure warning light.
Is that it on the report of the first outing?
Mark
1990 Van Diemen, the Racing Machine, CM AutoX, 2016 Frontier
You can try to make a street car into an autocrosser or you can do a lot less work and make a race car into a great autocrosser
I can report that the build looked beautiful and the car was competitive right out of the box.
Nice job Eric!
I spent much of last week wrapping up the fit install.
Wiring was simple, mostly plug & play. Aim Evo4 and G-dash (thanks David/Ellen @ Veracity!) plugged in to HPD harness. Basic info came right up without any configuration. Most time here was spent routing wires and protecting them. Battery finished the day with more voltage than it started.
I had Eagle Fuel Cells test and add a 4x6 access panel to the original cell. With that I was able to get all the HPD supplied parts inside the cell. Fuel filler neck required multiple bends added to it to get it accessible through the top motor mount. Dipstick guide tube added while I was there. Fuel pressure stayed @ 50psi and no leaks
Cooling is hodgepodge of VD and HPD parts TIG'd or silicone elbowed together. On initial startup one original welded elbow had a pin hole leak. We had a good Santa Ana breeze blowing, water temp came right up to 175 and stayed 175-188. Will add radiator fan to keep it cool at ProSolo's. Again, no leaks.
Maybe half of the HPD oil line fittings we're useful, the rest were sourced locally. I primed system with a socket on cordless drill before installing fuel cell/firewall. I didn't install the in line oil feed screen filter since VD pickup in tank has one. Hot/idle oil pressure dropped a little below spec but was fine on course. No leaks
We didn't make it to the practice Saturday due to the wheels not fitting. I don't know if it is a FC vs.FF issue or it my car has different hubs. With spacers, washers, installing parts backwards and a little turning of the hub nut cones (on a wood lathe!) we made it work for Sunday. Jon will be heading to the UCSD machine shop to make proper cones. Haven't checked tire pressures since Sunday but I'm gonna go with No Leaks.
I made two laps around the paddock before heading to grid. When not warmed up there is significant hesitation at throttle tip in. With stock Fit clutch/flywheel and 13/37 first gear car is super easy to get moving. LD200 reverse is also easy to get to compared to MK9.
On course the first run was very much about what is the car going to do? Car was quite loose (remove dual element wing and giant diffuser will do do that!) but made all the right noises, went, turned, stopped. When I stopped for my time slip a puff of smoke blew by but it was just the header wrap getting seasoned. I'll call that an acceptable leak
Spring, shocks, alignment will all get some attention but overall it was a great first outing on a new car. We ended up 2nd & 3rd in five car class. Jon just .070 out,, me 0.6.
Congrats on a great first outing with your new toy! From now on, you will probably get very bored since the engine requires approximately zero regular maintenance.
I have a 7" motorcycle radiator fan that will maintain the water temp when I switch it on, but it won't cool the engine when it's idling stationary.
Well Done! What a great Father-Son project! :-)
Looking forward to seeing it!
Barry
Solidworks
Hello.
Would you still happen to have the SolidWorks model of the RF chassis that you could share?
I run a RF90, and am also a SW user.
Andrew Mason
#32 OFFC
Working on car to make it better/faster is fun. I'm OK not working on it because I have too!
I have a 7" fan, figured I'd buy another and put two on the first radiator. I already love having an alternator, when the fans are in I won't have to "ration" the fan battery.
Big thanks to Barry. He blazed the trail on converting a Rf-94/5 to Honda power. Knowing it was do-able took away any fear of starting the project. Barry made a nice write up about what was required/different from a 99+ and posted many pictures for me to see how he fit everything together.
Also thanks to Keith Lobban and Neil Roberts for offering any info I needed along the way.
While I'm at it, Apexspeed classifieds and Dante Racer for selling me the car! (he has more cars for sale too!)
Andrew,
I don't really do computers... I'll PM you the kids email, he probably kept the SW stuff.
I do still have them, but they were pretty rough as far as measurements went. Definitely not super accurate, and they were made with the student version so it'll have those wonderful "for educational use only" watermarks everywhere.
Last edited by Jon C; 05.08.14 at 2:22 AM.
a couple pics from the weekend made it onto the internet.
https://www.facebook.com/media/set/?...1201601&type=3
Ran it without the rear bodywork to make sure there were no leaks or problems. Turns out we could've run it with the bodywork.
Very nice! Quite a color scheme. I can imagine having an alternator is a plus.
Are you bringing it to the Tour?
Mark
1990 Van Diemen, the Racing Machine, CM AutoX, 2016 Frontier
You can try to make a street car into an autocrosser or you can do a lot less work and make a race car into a great autocrosser
Mark, Probably just the Pro.
Neil's comment is the same as mine on my Old Mondiale, fans mounted on radiator will maintain, but not lower temps.
On this Rf-94 I plumbed the dual radiators in series and ducted in a 7" Spal fan on the first radiator. So far this is working well. Crows Landing ProSolo was 100*+ and the coolant never when above 200*. Turning on fan does lower temps
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