Given there are a few people that know engines around here, perhaps someone can help me fill in some blanks.

Engine specs for the NASCAR Sprint Cup are available online, and are approximately:
550lb ft @ 7500rpm
875hp @ 9400rpm

Now restrictor plates are also used in this series, but the only information I can find is that power reduces to 445hp (around half), and that the four holes in the restrictor plate are 22.6mm in diameter. Some more (vague) info here.

The only other restricted engine I'm particularly familiar with is our old favourite the MRT5.
In the bike:
66Nm @ 9500rpm
100hp @ 11500rpm

In the MRT5 (restricted but turbocharged, just to confuse matters):
69Nm @ ~5100rpm
64hp @ ~8000rpm

Now the MRT5 power reduction is relatively less than the NASCAR restriction (two thirds versus half), and clearly the addition of the turbocharger more than makes up for the loss in peak torque the air restriction would otherwise cause, but am I correct in thinking the drop in peak power rpm should be less affected by the presence of the turbo? Playing with the restrictors in LFS tells a similar story, but we all know that engine modelling in LFS is quite simplistic, so I don't want to base too much on that.

Could anyone make a reasonable, informed suggestion as to what the other three values would be for the restricted NASCAR engine? Or if anyone who follows this series can share any information that searching isn't giving revealing, even better! I'll still re-create the engine in LFS and then restrict the power back down to see what values it comes up with though, which should give me a starting point until somebody can come up with something more reliable.


Thanks

"NASCAR's Sprint Cup and Nationwide Series currently uses restrictor plates at Daytona International Speedway and Talladega Superspeedway. NASCAR routinely states that the Sprint Cup restrictor plate reduces engine power from approximately 750 hp to approximately 430 hp."

http://en.wikipedia.org/wiki/Restrictor_plate

Which I had already come across. That info is both outdated and insufficient for what I require. Thanks for trying though.

My test in LFS yields restricted values of:
440hp @ 8100rpm
314lb ft @ 6300rpm

Have you been building a stock car for your own use in LFS? You bastard.

Quote from Blackout :

Have you been building a stock car for your own use in LFS? You bastard.

lol, if he has i call beta test!

Quote from Bob Smith :

Which I had already come across. That info is both outdated and insufficient for what I require. Thanks for trying though.

My test in LFS yields restricted values of:
440hp @ 8100rpm
314lb ft @ 6300rpm

Sounds about right for the RPM at max HP, with the restrictor plates on I don't think they get them up much over 8000.

RPMs should go up to about 8500, but the max HP sounds about right at 8100.

Nice work there, mind sharing?

http://www.jayski.com/stats/restrictor.htm it's not what you're looking for, but it's an interesting look at the evolution of rules, events, and qualifying speeds over the course of restrictor plate racing.

As far as I know, this is still typical...
At Daytona and Talladega, the cars run a 390 cfm carb. At other tracks, 750 cfm carbs are the norm.

Quote from Blackout :

Have you been building a stock car for your own use in LFS? You bastard.

I guess it is for the game he helps developing.

Quote from PAracer :

http://www.jayski.com/stats/restrictor.htm it's not what you're looking for, but it's an interesting look at the evolution of rules, events, and qualifying speeds over the course of restrictor plate racing.

Thanks, interesting stuff.

Quote from zeugnimod :

I guess it is for the game he helps developing.

That's the reason behind this all, yes.

Quote from Blackout :

Have you been building a stock car for your own use in LFS? You bastard.

Well, my original intentions was just to get the engine in to test out the LFS intake restriction. But then I thought I'd like to see how one of these drives...

Quote from PMD9409 :

RPMs should go up to about 8500, but the max HP sounds about right at 8100.

Excellent, thanks.

Quote from PMD9409 :

Nice work there, mind sharing?

It won't be polished, pretty, or work with anything newer than X10, but I might well create a public version. After some initial testing, it makes the oval more interesting. Hard with mouse though, I'll have to plug my wheel in soon.

Glad I could help.

Quote from Bob Smith :

Excellent, thanks.

It won't be polished, pretty, or work with anything newer than X10, but I might well create a public version. After some initial testing, it makes the oval more interesting. Hard with mouse though, I'll have to plug my wheel in soon.

That's good enough for me.

What speeds are you getting? Because I have tried to "recreate" one in tweak before and all it did was burn every tire I threw at it!

Quote from PMD9409 :

What speeds are you getting? Because I have tried to "recreate" one in tweak before and all it did was burn every tire I threw at it!

Breaking 200mph at three points on the track. Seen 208mph but then ran wide through the final tight corner. Front right seems to overheat on R3s for me, 6 laps and you can notice the lack of front grip (temps over 125°C). Other three tyres are happy (running 34psi inside, 60psi outside). Will test R4s now...

Edit: Fine with R4s tbh. I should point out I'm running a maximum downforce config, but I don't have any drag values to go on, so let me know if the speeds seem too high or low.

http://www.youtube.com/watch?v=bRsfkoiAToI

When watching qualifying speeds at Talladega I don't see cars changing speed much, seem to be hovering around 185mph constantly.

Well, that's good R4's work. I hope someone can get their hands on drag values soon.

I'd expect the behaviour to be a lot more like that for the restricted plate circuits. Good reference for those though, as the drag for the car won't change with the restrictor plate (maybe drop a little as they can run more grill tape?).

Quote from Bob Smith :

I'd expect the behaviour to be a lot more like that for the restricted plate circuits. Good reference for those though, as the drag for the car won't change with the restrictor plate (maybe drop a little as they can run more grill tape?).

Correct, more grill tape in qualifying would add front downforce.

Found a book (made in 2008) that has a few values for the downforce on the front and rear of the car.

The last slide in this PDF presentation list a set of values for the CoT at a short oval, so I've used these as the numbers for the maximum downforce setup. This changes adds a couple of seconds per lap, I can only just nudge 200mph at one point on the circuit now.

I'm thinking of giving this a final bit of polish and give it a release, I'd like to get feedback on this car.

Bob, is this using your SuperTweak? Who knows, if the physics are fun enough and some-one chops together a 3D model ...

Quote from Bob Smith :

The last slide in this PDF presentation list a set of values for the CoT at a short oval, so I've used these as the numbers for the maximum downforce setup. This changes adds a couple of seconds per lap, I can only just nudge 200mph at one point on the circuit now.

I'm thinking of giving this a final bit of polish and give it a release, I'd like to get feedback on this car.

How much is the car modified from whatever LFS model you used as a starting point? Suspension, wheel base, track width, weight distribution? How close is it to a stock car if put shortly.

Quote from duke_toaster :

Bob, is this using your SuperTweak?

Yes, this is using my car editor that I started work on ~2 years ago. I've still not updated the program itself in ages, so patches newer than X10 aren't supported (and I won't be adding that anytime soon, either). I'll need to update the licence checking part before I can release though, as my both parts of my two stage system have been circumvented since then, and such functionality needs to work and work well in order to be approved for release, by, err, me.

Quote from Blackout :

How much is the car modified from whatever LFS model you used as a starting point? Suspension, wheel base, track width, weight distribution? How close is it to a stock car if put shortly.

The positions of the wings are about the only thing I can't move (at least not directly, I can move the wheels, and thus their positions relative to them, but that adjusts both together, not independantly). So the location of the engine, battery, fuel tank, passenger seats, etc, are all good, plus suspension geometry, 12 aerodynamic parameters, engine specs, body + flywheel inertia, free reign on tyre pressures (need 60psi for outer tyres), and other interesting but not relevant values (like the vertical alignment of the steering wheel, or removing front brakes, and many others). And of course the usual flexibility of setup and engine sounds.

As ever, the key part is getting accurate data, after that, I'm only restricted by what LFS models (or rather, what it doesn't, like asymmetric suspension settings and tyre sizes, or lack of live axle suspension) and the few things I can't edit. The killer for realistic online racing will be the drafting in LFS, so I don't view this quite as seriously as my initial set of cars that were going to be the mod, but I have very different goals for this project, hence I'm not waiting until I can get everything perfect before release. In fact, the very idea of this is not to release a finished piece of work, but to get feedback, and maybe have a little fun along the way.

Without editing the graphics, it won't look pretty (even more so if I were to move the drivers seat and put it out of alignment with the steering wheel), but such things aren't permitted to be distributed, so even if I knew how and did so, I couldn't share that as part of the package.

Quote from Bob Smith :

Yes, this is using my car editor that I started work on ~2 years ago. I've still not updated the program itself in ages, so patches newer than X10 aren't supported (and I won't be adding that anytime soon, either). I'll need to update the licence checking part before I can release though, as my both parts of my two stage system have been circumvented since then, and such functionality needs to work and work well in order to be approved for release, by, err, me.

Yes, you've been teasing people with your uber-tweak for ages now!

Quote :

*lots off stuff I don't quote to extend my post*

Ooh, interesting stuff I must say. For some reason I was the most impressed about the battery position having it's own value, but it does make sense. Is there a value for battery weight too? Truck batteries mmmm...Too bad you can't make 12 litre turbocharged diesel engines to work properly.

I wish there would be a special mod-license for the talented people like you to buy, well not you of course, because you don't have the time, but for people who have it. Slap on a hefty price, let's say 200 pounds and most kiddies stay away messing around making Civics.

Maybe get people to submit the ideas to a panel of clones of Bob*, then let them build them - and once finished, return the content to New Bob Army for feedback/comment/submission to Scawen. Obviously content would need to be non trademark infringing, but that only limits what stuff looks like and is called, NASCAR don't own stock car racing and no-one owns truck racing. And with some of the Shed Sports Car outfits, who knows ...

* Instead of human cloning, maybe assemble a scrutiny panel. I'd be happy to spend some of my time wading through ideas, even if 50% of them are brown and smelly.

For example the procedure would be

Bad idea (e.g. car with NOS). Submission of concept ==> Concept rejected.
Good idea (e.g. your stock car, or a truck). Submission of concept ==> Concept approved, permission to commence work granted ==> Stuff made using normal tools ==> submission to scrutiny panel ==> feedback issued by scrutiny panel ==> modifications made by original builder ==> submission to scrutiny panel ==> accepted by panel, sent to Scawen for final decision and/or inclusion.

Sounds like it is coming along very nicely Bob.

/OT: Bob, in your sig you have the road going setup pack updated last in 0.6A...

Quote from PMD9409 :

/OT: Bob, in your sig you have the road going setup pack updated last in 0.6A...

that's not a typo.

Quote from bunder9999 :

that's not a typo.

Never said it was, just want to know why it has that.

But that's offtopic, back to the experiment!

Just so you know the current state of progress, I just need to improve the offline licence checking (I've already fixed the online check), and I'll be ready to make this public.