LMP1 car

[Grintch]

A quick look at the US trackday/race car competition (costs are new, professionally built/assembled):

Spec Racer Ford (G3) - $40K, rather low performance spec car. Over 850 built (G1 & G2), mostly in the first few years when it was faster than a new Corvette for half the money (which hasn't been true for a long while, still won't be with the new generation 3 updates).

Formula/Sports Racer Enterprise - $55/60K, in theory a follow on to the successful SRF with a more modern & higher performing car. FE has a spec class, but somehwat more expensive ESR was stuck as an also ran in CSR (most cars were built as FE, no surprise). Less than 200 (150?) built. Maybe because it was never the value of the early SRFs. Running costs while maybe lower than FF, FC, F2000, are well beyond SRF.

Stohr WF1 - $70K, dominate Sports Racing car in DSR (& often CSR) for many years. Less than 100 built even if include FBs (not sure how closely related the FB is to the DSR, but basic configuration is the same). Blamed by some for killing off the homebuilt & kit race cars and raising the price of entry to be competitive. Great car if you can afford it. DSR & CSR classes now being shaken up & revised into P1 & P2 (P2 is supposed to be a cheaper class than DSR). High operating costs.

Radical - Various models. Generally a bit heavy and non optimized for their US classes. Have a US Radical one make series but haven't been a big factor in SCCA club racing (probably more total cars built [sold in the US] than Stohr). Have endurance & "street" car options. Maybe lower operating costs than Stohr (built more with endurance in mind)

Diasio 962R - $80K, high end track day car. Potential for CSR or ASR & endurance use but not optimum. Few built. Supposely low operating cost for a SR.

Ariel Atom - $50K, local spec car series plus rather extreme weekend/track day car. Doesn't generally fit well into US race classes, but could in theory be driven to the track and financed. Most are built for street use. Probably low operating costs.

Corvette - $55K, street & trackday car. Also has severeal racing classes to choose from (but need more $$ to covert to appropriate specs). Has all american favorite combination of relatively high power & V8. Can be finanaced and driven daily making it more cost effective. Tire & brake pad consumption costs are high for track use.

Camaro GTA - $66K, road racing stock car. Has all american favorite combination of relatively high power & V8. A bit crude but cheap to operate. A used one is hard to beat for speed (& noise) for the money.

P.S. I think option 2 is really the best option if you want to sell more than a handful of cars.

[autodoctor911]

Is this your design:

http://antonaengineering.files.wordp...t_excerpt1.pdf

If not, it must be similar, correct?

[connersportsracers]

This class will have too much Mass to come close to a DSR for speed, the Straight acceleration will be very fun, just too heavy to corner. The DOT Slicks and 3" of ground clearance, remember it is Improved Touring.

Addressing the Downforce, At 100 MPH - The underside of the car will give about 500 to 700 lbs of Downforce for FREE or Almost no Horse Power, But the bigger the tunnels the more drag or Horse Power to push the car. Everything on the top or the side of the car giving downforce will create A LOT of Drag, I think a good number for 1000 lbs of DownForce would be 50 Horse Power at 100 MPH.

The Drive Train Donor cars weigh 3000 lbs or more, the Miata is about 2700 lbs. I expect the Sports Racers to weigh 1500 to 1700 lbs + Driver and 12 gallons of fuel (84 lbs).

A Clean Aero set up will be normal, I hope the top speed will be less than 155 mph

A homebuilder will want to use the donor car to make a Jig to Locate the Engine and Suspension mounting points, then make further small adjustmenst from there. Becarful lowering the engine to suspension mounting points, even 2" may cause problems you'll find later. The Boxster, you'd want to use the whole car to make a Front and Rear locating jig.

I have the 1 1/2" Tube Chassis ready for kit production, I am working on an Aluminum Tub Design with a 1 1/2" Tube Upper Structure, (I worked on a Tiga GTP Light car in 1989 and it will be somewhat like that) It needs to be strong enough to take a hit from a v8 Mustang.

Thanks for Understanding the Idea and not saying it will not work.

to connor: Wow, a 2.8L sports racer with ASR aero rules, and modern aero development. That sounds like a formula for some really fast cars. How are those miata or LT suspension components going to hold up to several thousand pounds of downforce in an endurance race, no less? OK, I see that is for the front, still a little weak for a 250-300HP car with high downforce. I would allow the GT version too, as well as allowing any duplicates of the rear suspension used, up front, making spares easier.

I like your concept. I am not sure how many home builders are out there, but it is an interesting formula that could definitely be as fast or faster than DSR, or CSR type cars for less money if done right.

I hope you accept drivetrains from mid engined cars as well(Fiero, MR2, Boxster) It would open up the class to possibly be a PCA class as well. I would love to build a Prototype with a Stock base Boxster drivetrain, and a lightweight tube chassis and ungodly downforce, if it could be done for a reasonable amount of money, and I'm sure there would be a pretty large market for such a car, with all of the Porsche club racers and even those wishing to have a track day special instead of tearing up their expensive late model Porsche.

I think you could gain some traction with this concept if you get some cars built and run them. I think the rules may need some tweaking though, and I wouldn't limit it to IT endurance events.

I think a 2.5/2.7L porsche engined version(200-265HP depending on year) would be the best, most marketable version. If it were to resemble a RS spyder, or better yet, the new LMP car that Porsche will soon release, all the better. Base Boxster engines and transmissions are not too terribly priced, and should be extremely durable. I would be willing to bet that an engine and transmission would last for many seasons in stock form. The Spec Boxster and Cayman interseries(slightly different engine) cars have proven to have very long engine life, with very few, if any failures.

P.S. I would suggest allowing base Boxster engines up to 02 for the current 2.8L class, unless there are other engines available with more than 217HP, then there is the 03-04 2.7 with variable lift cam(245HP). If the 217HP is too much, the 2.5 used from 97-99 is under 200hp, but more limited in supply, and less reliable. If you are just limiting to 2.8 L engines, the the 265HP direct injection 2.7 from the new(2013up) Boxster would be killer. The engines are fairly heavy though, as are the 6 speed transmisssions. It may be prudent to allow the more powerful engines at a higher minimum weight with driver if the cars are not using much ballast with the lighter engine options and a larger driver.

[peat]

Is this your design:

http://antonaengineering.files.wordp...t_excerpt1.pdf

If not, it must be similar, correct?

No autodoctor911, that's not mine, but my design is base on the same regulations...so yes, you could argue that it's "similar"

[Grintch]

So CM car (bike engine, enclosed 2 seater)? I hope better looking than that in the design project. Have you looked at the new P1 & P2 (replacing CSR & DSR) SCCA rules?

[peat]

So CM car (bike engine, enclosed 2 seater)? I hope better looking than that in the design project. Have you looked at the new P1 & P2 (replacing CSR & DSR) SCCA rules?

hahaha hopefuly it does look better! Yes, regulations is num. 1 on my priority list.
What do you think about the concept!?

[Grintch]

[QUOTE=peat;417548]hahaha hopefuly it does look better! Yes, regulations is num. 1 on my priority list.
What do you think about the concept!?[quOTE]

Interesting. There have been CN cars imported before but no CM's. The US equivalent are lighter single seaters, so the CNs haven't been a big success under the old CSR rules.

Might want to take a hard look at the Diasio 962 experience. The older versions were motorcycle engined DSRs relatively close in concept to a CM car, while the current version has moved to a Renesis Rotary powered trackday car.

[peat]

[QUOTE=Grintch;417572][QUOTE=peat;417548]hahaha hopefuly it does look better! Yes, regulations is num. 1 on my priority list.
What do you think about the concept!?

Interesting. There have been CN cars imported before but no CM's. The US equivalent are lighter single seaters, so the CNs haven't been a big success under the old CSR rules.

Might want to take a hard look at the Diasio 962 experience. The older versions were motorcycle engined DSRs relatively close in concept to a CM car, while the current version has moved to a Renesis Rotary powered trackday car.

A company is just starting to import CM's. Considering that the US equivalent are lighter single seaters and CM's have an aero advantage, I think that CM's might have a place in the US.
I've been reading about the Diasio 962 and I have found some people not very happy with motorcycle powered cars.

[Wren]

I've been reading about the Diasio 962 and I have found some people not very happy with motorcycle powered cars.

Yep, if you want to do a 24 hour racer with a bike motor, make it easy to swap. You can expect to go through at least two motors in that time period.

[peat]

Yep, if you want to do a 24 hour racer with a bike motor, make it easy to swap. You can expect to go through at least two motors in that time period.

Yes, I've been following the 25h a couple of years. I want to tackle the problem...I have some ideas...

[rburgess]

Looking at the results for this year's 13 hour race at VIR and the 25 hours of Thunderhill, I don't think there is any issue with running a bike motor in endurance races.

[autodoctor911]

A company is just starting to import CM's. Considering that the US equivalent are lighter single seaters and CM's have an aero advantage, I think that CM's might have a place in the US.

Can you quantify the aero advantage for a CM over single seater?

Or just in general a closed CM vs an open CM,

If you're talking about P1 or unlimited aero classes, I would think a single seater with tunnels would beat a closed CM on downforce and even drag.

Is the lower CoD on the CM enough to make up for all that frontal area?

[peat]

Can you quantify the aero advantage for a CM over single seater?

Or just in general a closed CM vs an open CM,

If you're talking about P1 or unlimited aero classes, I would think a single seater with tunnels would beat a closed CM on downforce and even drag.

Is the lower CoD on the CM enough to make up for all that frontal area?

I can't give you quantitative answer really but a qualitative one.


Open wheels vs closed wheels

The basic comparison to do is open wheel vs close wheels. Closed wheels are far less draggy. Big round rotating wheels are big sources of wake of course.

Closed wheel: open vs closed cockpit

Hard to say, both have pro and cons. Let's consider flat floor in both cars.

Closed cockpit have a larger area to work with. Therefore you can generate more down force at the cost of a bit more of drag, better straight-line speed... driver' head is much more stable, this means less fatigue and no aero interference. Moreover the flow is more predictable! Not an aero reason but is safer.
On the down side (not aero reason really), that cost poorer visibility, might cost longer driver switch times, more complex (air conditioning, wipers...)...

On the other hand, open cockpit have less frontal area and in theory less drag. If it's not well design you might end up having a "recirculation" problem in the cockpit, causing a lot of drag. The flow might be affected by the driver' head (driver' head unstable in an open cockpit). Moreover, straight-line speed is usually lower than a closed cockpit. Even if well design, any change in the flow can trigger the recirculating problem mentioned before. And the most important one, the flow might be not as predictable as in a closed cockpit.

Both options are completely valid (Audi have win Le Mans with both). The difference in terms of aero are not that big, but closed cockpit, in general terms, have an advantage IMHO. From my personal point of view...I rather prefer closed cockpit than open cockpit. Reasons:

- More predictable airflow.
- Higher down force= higher cornering speed.
- Usually higher straight-line speed.
- Safer.

I think is much easier keeping the airflow out of the danger areas and redirect it into useful ones with a closed cockpit than with an open one. Moreover, IMHO the airflow is more predictable.


Single seater with tunnels vs CM (flat floor) is not a fair comparison. Tunnels are the most effective way of generating down force at a very low drag. On the other hand, in equal conditions (same weight, power, tunnels...), I would go for the CM.

This reminds me the typical comparison F1 vs LMP1. A few years ago Adrian Newey was asked to envisage an F1 car that ignored the rule book (his famous RedBull X2010). His design was the logical one, a closed cockpit-closed wheel single seater. The main difference between Newey's design and a LMP1 car are basically the cockpit (two seater in LMP1 vs single seater in F1) and the mandatory front covert/bodywork in the LMP1.


P.S: a variation in df= a variation in vertical load= a variation in tyre load= a variation in grip. In general terms, you always wants to keep your vertical load and ride height as stable as possible to control tyre load.