Stohr vs. Van Diemen

[npc5515]

Hey guys,
What are your personal opinions about FB Stohrs vs. Van Diemens? Thanks!
-Neil

[carnut169]

You know the only Van Diemen FB are conversions, right? Most with the Novak kit.

RFRs are built by Ralf Firman who used to design the Van Diemen cars.

[JohnPaul]

Neil, People go fast and win in both cars. I personally would love to get a newer VD (2-3 years old) and do a Conversion, with a 2011 ZX10!!. You can't go wrong with either but the RF98 conversion for sale here for $20k is the move.

[Richard Dziak]

Contact Dustin Wright over at Phoenix Race Cars, or Keith Roberts on the east coast. The Phoenix chassis is quite the car. There are other manufactuers in this class to choose from. Many racers are attracted to individual body style, which you will find that each constructor in the FB class has there own unique style.

It's a great class, no matter what brand you buy.

[F1000champ]

Whichever FB you buy, I hope you will consider running in the F1K Series in 2012. All of our races will be in the eastern half of North America, so you won't have to travel far.

There are 10 manufacturers currently to choose from as well as a few used cars for sale and they are listed on our website: www.F1Kseries.com .

It's a great class and whether you're interest is club racing or entering one of the pro series, you're going to really enjoy these cars.

[Wren]

My experience has been that people are never going to be honest about cars on here because they are too nice about it. I have seen some advice that is downright bad on here when it comes to car choice.

Go to some races, look at some cars and talk to people in person, where they are much more likely to give their honest opinion on cars. Look at results from when people are in the same place at the same time and apply some sort of sliding scale based on driver talent and budget.

[Rick Ross]

Neil,

One thing to consider is weight. Depending upon the weight of the driver, you may have trouble getting down to minimum weight in some of the current FB cars.

[JohnPaul]

My experience has been that people are never going to be honest about cars on here because they are too nice about it. I have seen some advice that is downright bad on here when it comes to car choice.

Go to some races, look at some cars and talk to people in person, where they are much more likely to give their honest opinion on cars. Look at results from when people are in the same place at the same time and apply some sort of sliding scale based on driver talent and budget.

[FONT=Verdana]Ok, well everyone knows you're terribly honest, quite knowledgeable and know what’s up, what are your picks in order, I'll get you started:[/FONT]
[FONT=Verdana] [/FONT]
[FONT=Verdana]1) Citation, no disputing since they finished 1 & 2 at the runoffs[/FONT]

[starkejt]

Hang on a sec, let's not get carried away calling Wren knowledgeable.

Seriously though, Citation is a great chassis, but getting one is a quest of epic proportions. You can't just call up and buy one like you can a stohr or firman or phoenix.

I will add that I think a properly sorted late model VD makes for a pretty good car as well.

[KevinFirlein]

quick hijack , but I wish Steve would consider building complete rollers. After running Erics car at VIR and seeing RFR's ( in both classes) sell and talked about Radon sales I have no doubt citations would sell. I do fully realize the economy of selling and supporting small distribution cars sucks.

edit - for the record since there was only 2 choices I checked Van Diemen as I think there are plenty of developement oppurtunities.

[Wren]

[FONT=Verdana]Ok, well everyone knows you're terribly honest, quite knowledgeable and know what’s up, what are your picks in order, I'll get you started:[/FONT]
[FONT=Verdana] [/FONT]
[FONT=Verdana]1) Citation, no disputing since they finished 1 & 2 at the runoffs[/FONT]

I have never made it a secret that I think the FC based cars are the cars to have. I base that on results. Coop was tearing it up early in a nova-diemen and pritchard was on another level in the Piper. I think that Jay Novak with a Piper in his hands is scary. The Piper is a great car and once the aero is updated to exploit the FB rules then they could rewrite what is possible in an FB. Jay is easily the most knowledgeable guy around when it comes to aero, except for maybe Ben Cooper. I can't imagine a better guy to develop the car.

Hang on a sec, let's not get carried away calling Wren knowledgeable.

correct. I've met that guy and I wouldn't listen to him.

[ghickman]

STOHR:
*Greating looking car with topnotch bodywork layup
*Lacking mechanical grip (in my opinion) due to lack of any ARB's and using only springs and shocks to control balance.
*Yes JR is fast in one but he could likely put a Skate Board on the front row. Looks to be a handfull to drive from my observation.
*Parts supply excellent
*Factory Support excellent
*Build Quality excellent
*Cost $35-60k

98 or NEWER VAN DIEMEN CONVERSION:
*Slightly dated looking
*GREAT mechanical grip
*Coop went quick virtually all the time
*Lacked good brakes. My suggestion would be to get a full set of my new VD UPRIGHTS and run PFC 4 piston brakes and big rotors
*Parts supply excellent
*No Factory Support
*Build quality typical British so so
*Cost $20-30k

Others to consider in order of my preference:
1) Phoenix 2011 chassis (yet to be in the right hands but may be changing soon)
2) Citation
3) RFR

[starkejt]

I have never made it a secret that I think the FC based cars are the cars to have. I base that on results.

Then why not stick a GSXR in your DB6 FC?

[preform resources]

I agree with Kevin on the VD chassis issue, these cars need more development,
that is all,unfortunately it is aero development,,,,and that is not cheap!!
Dave Craddock

[glenn cooper]

You know the only Van Diemen FB are conversions, right? Most with the Novak kit.

RFRs are built by Ralf Firman who used to own Van Diemen cars.

It's OK folks, he's drunk on French wine w/ his beautiful French Mistress, Mygale

Sean I'ma let you slide on this one, while the Elan VD's of Cooper The Brit, Beattie The Floridian, and JP The Jerseyite are by name only not just VD, they definitely are VD's.

I do however think the OP is refering to converted FC cars, just not 100% sure.

[carnut169]

was not all that long ago that I had a Van Diemen conversion...

I believe the VD is a faster car in the right hands, but you can just go out and buy a Stohr while the VD conversion is a whole lot more work (although there was one for sale recently at a crazy good price).

Just wanted to be sure the OP was aware of the difference.

[RussMcB]

It sure seems like a purpose built, start-from-a-clean-sheet-of-paper F1000 should be much better than a converted car built to FC rules, with big heavy engine, transaxle, etc.

[Mike Devins]

It sure seems like a purpose built, start-from-a-clean-sheet-of-paper F1000 should be much better than a converted car built to FC rules, with big heavy engine, transaxle, etc.

The Citation seems to be doing a pretty good job for a design that started off as a FC.

[JohnPaul]

It's OK folks, he's drunk on French wine w/ his beautiful French Mistress, Mygale

Sean I'ma let you slide on this one, while the Elan VD's of Cooper The Brit, Beattie The Floridian, and JP The Jerseyite are by name only not just VD, they definitely are VD's.

I do however think the OP is refering to converted FC cars, just not 100% sure.

New York Damn it! I know do it to piss me off.......

[iamuwere]

New York Damn it! I know do it to piss me off.......

What a Jersey response....

[F1000champ]

There are alot of different make cars in this class that are all competitive. Each one has its own plus & minus, but in the hands of a good driver competitive.

It's one of the many things that makes this class so exciting and attractive, unlike the many "spec" series out there.

[S Lathrop]

The Citation seems to be doing a pretty good job for a design that started off as a FC.

Just to add to Mike's statement:

The Citation FB is close to a ground up design. The car shares the frame and the body forward of the roll bar with the FC. The suspension for the FB and FC are different and only share the rear drive shaft and uprights at both ends.

Mike makes the diffuser for the FB car and that is not shared with the FC. The aero package for the FB is similar to the FC but not the same. From the roll bar back the FB is a standalone design. Mike also makes an attenuator for the rear of the car as well.

My rear drive assembly is Stohr inspired but built around a Variloc differential. The diff. is an evolution of the Variloc mini stock unit that has been in production for over 15 years and earned more than 15 SCCA national championships.

There are two design approaches to FB: F1 look alike or the FC approach. The FC approach is F1 derived from the time when the rules for F1 and FC were similar. I spent many years engineering Indy Lights with the Lola T97. Interestingly the rules for FB and the Lola are very similar and the down force levels are very close given the horse power and weight of the cars. At 150 mph both cars make more down force than their racing weight. Both are flat bottom ground effects cars.

The one area where the FB demands more than FC is in the torsional rigidity of the chassis. I have been testing cars since the late '70s and my current FB chassis equals the best aluminum monocoque that I ever tested. It also is very light. I don't think I can maintain that weight / strength and build a raised nose car. A stiffer the chassis has the potential to produce more mechanical grip. That is at the crux of the Radon debate.

The raised nose is a quest to increase front down force with a narrow track car. FB is a wide track car. The front wing is narrower than the inside of the front tires if you build the car to the maximum allowable track width. The raised nose also complicates the front geometry and the front mechanical grip.

This is a long post but the question of VD vs Stohr demands a better answer. The Citation, Piper and converted VD represent one disign approach vs. Stohr, RFR, Phoenix, and others. Elkhart makes this more relevant because straight line speed is so important. In any case this makes FB one of the most interesting classes today.

[Wright D]

I raised the foot box on the F1K.9 and F1K.10, and I was able to increase the stiffness of my chassis with out a weight penalty, and ANYONE who has seen a Phoenix (F1K.07 through to the F1K.10) knows that it is a stiff and light chassis. I spent days running FEA tests of our chassis, and making changes till I got the light weight and high stiffness numbers I wanted. A raised nose dose not imply low torsional stiffness or a flexible chassis.

Like wise, there are aero benefits, that I out line in another post here on apex. Along with a cool CFD image.

[Rick Ross]

The one area where the FB demands more than FC is in the torsional rigidity of the chassis. I have been testing cars since the late '70s and my current FB chassis equals the best aluminum monocoque that I ever tested. It also is very light. I don't think I can maintain that weight / strength and build a raised nose car. A stiffer the chassis has the potential to produce more mechanical grip. That is at the crux of the Radon debate.

Hello Steve,

What was the measured torsional rigidity of the aluminum monocoque that you refer to in your post? Was it something like an 80's vintage Atlantic or F3000 car?

[S Lathrop]

Dustin;

I am trying to supply cars for three classes, two of which make it very difficult to build stepped noses.

As to torsional rigidity, I do know how my cars stack up against other cars that I have tested such as a Swift 008, a March Indy Lights, and a Stohr DSR. I can say that what I was told about the cars I tested was not necessarly what I found in actual testing. All my tests were on cars as raced. I use the system as a diagnostic tool. It is also a number that I use in setups.

I will say that I have not spent any serious effort designing a stepped nose car and I have been burned a few times in the past when I did not get the nose shape right on cars that I have built. Consequentially I build what I have confidence in.

In their time there have been three really competitive FB cars, Coop's VD, Pritcherd's Piper and Dixon's and Schweitz's Citations and all three cars have been essentially the same. That for sure doesn't mean that there is not a better way. Maybe you are heading in the right direction.

[R. Pare]

I'll just pipe in and say somewhere between 5000 and 7500 ft.lbs/degree. The next highest above that was a March Indy Lights tub (aly lower half with a carbon upper half) at 16000 if I remember correctly. ( Edit: The Swift 008 was below that substantially - what a real POS car that was!) Most "modern" tube frame cars in these classes range from 4000 to 6000 or so - anything below that and the car will be extremely handicapped.

[Rick Ross]

Richard,

Were these torsional stiffness values measured at the front and rear axle locations? And for the monocoque tub car stiffness (e.g. Swift 008) are you referring to the complete car, or just the tub?

According to Swift, the 008a tub stiffness was 13,200 ft-lb/deg, and the complete car with trunnions was about 3800 ft-lb/deg.

[R. Pare]

Rick:

That was/is fully assembled torsional stiffness at the axles, with the exception being the Swift. Why they wanted to brag about such a sloppy car is a complete mystery.

[Charles Warner]

For reference: Ralt "factory" data showed 3900 for the RT-40 and close to 5000 for the RT-41 at the axles. As always, consider the source.

[Fred2]

STOHR:
*Greating looking car with topnotch bodywork layup
*Lacking mechanical grip (in my opinion) due to lack of any ARB's and using only springs and shocks to control balance.
*Yes JR is fast in one but he could likely put a Skate Board on the front row. Looks to be a handfull to drive from my observation.
*Parts supply excellent
*Factory Support excellent
*Build Quality excellent
*Cost $35-60k

98 or NEWER VAN DIEMEN CONVERSION:
*Slightly dated looking
*GREAT mechanical grip
*Coop went quick virtually all the time
*Lacked good brakes. My suggestion would be to get a full set of my new VD UPRIGHTS and run PFC 4 piston brakes and big rotors
*Parts supply excellent
*No Factory Support
*Build quality typical British so so
*Cost $20-30k

Others to consider in order of my preference:
1) Phoenix 2011 chassis (yet to be in the right hands but may be changing soon)
2) Citation
3) RFR

Why 98 Van Diemen?
What changes make the 98 and newer ones, the one to go with?

Thanks!

[Northwind]

Better suspension design, better aero, and a whole lot easier to work on.

[glenn cooper]

Why 98 Van Diemen?
What changes make the 98 and newer ones, the one to go with?

Thanks!

That generation chassis is what bolts up to the Novak Conversion, of which I believe 5 kits were ever made.

HRP has a kit that bolts upto a highly modded '94 or so yr model, but so far has not sold any in the US to my knowledge.

[Jnovak]

That generation chassis is what bolts up to the Novak Conversion, of which I believe 5 kits were ever made.

We built a total of 8 Glenn & would be happy to build more. We also will have lots of new bits on the way for next season.


Thanks ... Jay Novak

[Fred2]

Better suspension design, better aero, and a whole lot easier to work on.

Better as in a minor evolutionary development, or major, as in you would be out of your mind to get a older car?

I am looking to get into the class, and I see some older home built conversions at an attractive price. As long as the older cars hare not totally obsolete, I would consider investigating them further.

[LenFC11]

older car is completely different. 98+ is a current car, well upgradeable to current, 01 is the start of the wide track cars..

[Mike Devins]

Better as in a minor evolutionary development, or major, as in you would be out of your mind to get a older car?

I am looking to get into the class, and I see some older home built conversions at an attractive price. As long as the older cars hare not totally obsolete, I would consider investigating them further.

The Novak conversion is a proven commodity (check out Coops performance with his), you have the advantage that all of the suspension components are a direct carry over from the Vandieman FC which translates to readily available spares. Also depending on your physical size the 98 may be a better fit, later cars a a little more roomy.

The HRP chassis kit has been proven DSR configuration, there is one FB conversion that is using it but it has really just hit the track I do not have a lot of feedback on it as of today. It is not a bolt on, it is weld in kit. The rear a-arms on the original RF90-95 is really pour and when I did the design for the back of the car we scrapped all of the original stuff, I do reuse the shocks and uprights but everything else gets replaced.

I have seen several conversion that are worthy of consideration and more that I would be leery of.

I would look hard at the NOVA conversion that is for sale - you can not build that car for that price.

[BERG Racing]

Can the wide track or narrow versions of the VD be used with the 8" and 10" wheels?

Also what are the major aero rules differences between FC and FB?

[RobLav]

I highly doubt the 8" front wheels will be legal within the 72" width rule on the wide track A-Arms.

[DonArm]

"Seriously though, Citation is a great chassis, but getting one is a quest of epic proportions."

I have chosen to take on the challenge of, as quoted above, the "quest of epic proportions"
I spent almost a year and a half looking at all of the options and felt that even though the Citation is more of a project than the other "off the shelf cars" it IS the car to have if you want to be fast in FB.
If you don't believe me go back and look at what car has the most track records in FB right now. nuff said!

[BERG Racing]

I would admit that the Citation has proven very competitive so far but I don't think the fields in FB are really deep enough to claim it as the car to have. It would seem to me that there would more of them running in the various FC pro series if it were that good. Jon's pro FB series should be very interesting this year.