Chase USA (some helluva cool stuff)

Discussion in 'Vehicles' started by Johannes Rojola, Feb 23, 2012.

  1. Gearjammer

    Gearjammer Registered

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    Absolutely, Chuck Berry would fit right in as well. Though I prefer Johnny B Good :)
     
  2. jtbo

    jtbo Registered

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    NOTE: Anything in this video is subject to change and does not represent final quality of the mod!


    It might be that this motor is not ending up to this car as there can be some space issues, engine is relatively accurate 428 Super Cobra Jet, that I made earlier for another mod of mod, but it sure makes that bucket fly, end speed something around 220kph, 3rd gear shift point around 160kph (100mph), almost lost it at one point, not the easiest to launch for sure.

    I'm not perfectly happy to tires, I have been making lot of them and I always end up to tires that grip too well in lateral direction and too poor to longitudal direction, but as there has not been much of anything new information about how to get temp bristle spring values rest than for vertical, it is bit of shooting blind. But eventually there probably will be some improvement to that.

    Anyway, I thought that this small peek might be interesting for you :)
     
  3. Gearjammer

    Gearjammer Registered

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    In real life it is very easy to lift the front tires off the ground with even a small block V8 like a Chevy 327 engine unless you are using narrow rear tires. Most T-Buckets I have seen use tires on the back that are almost as wide as the F2 2012 tires in game. I think the size of them was around 315/35 or something like that. You get the point though, right? The front end on those is very light.
     
  4. Johannes Rojola

    Johannes Rojola Registered

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    That would require some "additional" grip, which we have trouble getting in our tires. I think jtbo is currently battling with this issue?
     
  5. jtbo

    jtbo Registered

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    Engine and transmission are quite heavy there and quite far from rear axle, also stance is very much of nose down, I did some calculations and came up with 53% front weight with 302 + toploader, but most of the issue I have is grip when accelerating, it is not sticking, but when cornering it sticks way too well, same with any car and every tire so far.

    I know suspension is ok, so it probably is in tires. To get front end up I would need a huge amounts of grip, more than what 60's formula cars have.

    45/55% I have seen to be for one real t-bucket, but it had metal body vs fiberglass here to get weight down.

    Out of interest I need to now try to make one with such version that lifts front wheel off the ground, but not so sure if it should be possible to lift fronts on street, maybe at drag strip only?
     
  6. jtbo

    jtbo Registered

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    Not so sure if I ended up any realistic values, but resulting performance is quite lot better than before as I adjusted again tempbristlesprings.

    I can get tiny bit of lift from one front tire, might got lot more on strip, but certainly improvement.

    Now I need to find more real world data from T-buckets as with every other car, aim is to make cars from real data to represent real world versions, so lot of research is always needed, even T-bucket is something where one can choose parts quite freely, I want to make them to match realworld as well as I can.

    For example different engine means different weight distribution, different weight, different inertia, center of gravity changes usually, for some cars suspension was different with different engines.
     
  7. jimcarrel

    jimcarrel Registered

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    I couldn't quite put my finger on songs done by the Platters. Googled them and ended up recognizing the group. I did like them, but can you imagine mixing up tracks of Platters and CCR?
     
  8. Gearjammer

    Gearjammer Registered

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    @jtbo: I have seen in real life on the street T-Buckets lifting the front end up quite a bit. One person I talked to about it said that if he wasn't careful he could flip the car over with all the traction he gets and the low weight of the car. It could be the suspension setup though. Most T-Buckets I have seen use a 4-link rear suspension which is a bit of a high end suspension for a street car. I don't know that rF2 is capable of emulating this type of suspension.

    To give an idea of the weight balance and how much the car weighs, one man that is in decent shape could lift the front of the car to his waist but would not be able to lift the rear off the ground. I have witnessed this as well. Most all the T-Buckets I have seen have avoided big block engines because of how easy it is to lift the front.
     
  9. martymoose

    martymoose Registered

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    I take it corners arent a hotrods specialty as you didn't want to attempt the turn ;)

    Looks cool but are these going to be mostly for drag racing or can you use them on proper race tracks too?
     
  10. Max Angelo

    Max Angelo Registered

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    Different cups of tea for sure. :)

    I was thinking to the hot rods golden era, say from mid fifties to mid sixties, so few years before the birth of CCR!
     
  11. jtbo

    jtbo Registered

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    I wrote long reply, but forum monster ate it, despite I tried to save it by ctrl-c.

    Anyway here are real weights from some cars, also there is mentioning of 70% rear bias for drag racing, I guess engine is just moved towards rear then.
    http://www.tbucketeers.com/threads/weight-front-and-rear.12521/

    Engine and transmission make up some 40% of all weight, rest of the running gear, rear tires, axle so on, make together with engine and transmission some 50% or even more of the weight.

    Fiberglass body is only 40-50 pounds, add seats, floor, trim etc. But still very little weight sitting on top of rear section of frame, around 400kg at front is quite a bit to be lifted up though, must of been drag racing t-bucket with only 30% of weight at front?

    But also I think that tires suck at the moment, there is still bit too little bite, but I think that when I get them right and set drag racing weight distribution it probably lifts quite easily, if rF2 engine is able to handle those forces correctly, it surely is something ISI has not thought when making engine, actually almost all our vehicles are such :D


    Anything can be driven around corners...

    Of course there will be some different challenges.

    Firebird was surprisingly well handling car for it's time, also Vector W2 is something that will give run for Corvette, Ferrari etc. W8 was very closely the same, at 1991 they tested 0.97g and stopping distances that put Ferrari's to shame, Clarkson of course hated it, he hates anything that comes from US, but despite few quirks it was and still is one of the fastest machines and certainly fastest 3spd automatic production car ever made. Well, "virtually no centering force" might kill the fun for some, but that is how they made that car.

    It is really easy to make car feel great in rF2, but to make it real specs without car feeling overly slippery seems to be bit of challenge at least for me, but every day learning something new, hopefully getting them all right at the end.

    There will be upgrades to cars that are of course bit drag racing themed as this is all about US car culture and going fast on straight line has been popular there, but I think that with such variety of vehicles there will be several machines for curvy tracks, open roads and also for drag strips.

    Also there is off road capable cars and then there is Kenworth, which is really good at ramming, well it would be, but there is issue with tires, they go berserk, I posted about it to modding help section but as nobody else probably is not attempting to create such heavy machine, there has not been much of replies yet.
    I made truck spec tires for it, but some value seems not to be working at all as tires kind of explode after a moment of driving, freezing simulation, but maybe solution can be found for that.
     
  12. Gearjammer

    Gearjammer Registered

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    Let me guess, your Kenworth doesn't like 100 PSI tire pressure?
     
  13. jtbo

    jtbo Registered

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    Overall stiffness of tire is perhaps too much, of course that does include tire pressure too, but there are also damping which is bit of mystery, even I have general idea, I have not yet understood how to compute that, rf2 tires are one big wall to be climbed, but I guess it is same for others too that aim to as perfect realism as possible.

    There are probably a ton of formulas that help how to compute many of the parameters used in realtime section, but without having degree in tire physics it takes bit of time to first learn what is effect of parameter and then how to set it properly without knowing formulas. Would be lot better and easier with formulas of course.

    These for example are present on some ISI tires not all:
    TemporaryRingMassInertia=(6.39301881493281,0.5447855575547635,0.2997520911993927,0.29975209119939156) // mass, inertia (x,y,z)
    TemporaryRingDamper=(0.08,0.085,0.085,0.13,0.12,0.12) // x,y,z,p,q,r


    Then I think tehse make big issue as values are so much higher, spring 1st and 3rd parameter are something out of whack, I just throw 1 at front of them, middle one came from tire tool, so it is quite a lot more than any of 'normal' vehicles.
    TemporaryBristleSpring=(124000, 159054, 131500) // Lat/Vert/Long

    And these haven't got much clue, well I know how they affect hysteris of tire, but ISI tires have them always quite low, are they even related to spring values, and is there way to calculate them, is again what I would need to learn.
    TemporaryBristleDamper=(0.5, 1.2, 0.5)

    Would gladly give tire making to someone else, but there probably just are no more than 5 people that actually understands and can make rF2 tires correctly now and probably all of them have their hands full already, so very slowly I try to find bit here and bit there to make better tires, can't accept poor tires of course.

    Anyway I did put BT20 rear tires to t-bucket and there is not huge difference actually, but then again tires I have been making are based on BT20 tires and there are not huge changes to anything else than size, I need to learn more to be able to make something else than ISI ripoff tires ;)
     
  14. Johannes Rojola

    Johannes Rojola Registered

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    And something new in the pipeline....

    [​IMG]

    I wanted to do the '68 model because that was only year when Oldsmobile used this front fascia.
     
  15. jtbo

    jtbo Registered

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  16. Gearjammer

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    Ah yes, the Pontiac Vista Cruiser, nice job
     
  17. jtbo

    jtbo Registered

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    They had it branded as Pontiac over there along with Olds?

    Only thing I found was this, you could probably buy such car for that rate of 300 per day!?
    http://www.ghostlightla.com/inventory_details.php?id=267

    Anyway that company has quite a fleet of vehicles there :eek:

    Pontiac version looks to be quite rare, not sure how it really is, but I saw one site mentioning 71 with 455 being over 6000 in good condition.

    Anyway, I found something interesting, really lot of head flow tables, I guess there are indeed thousands of them:
    http://users.erols.com/srweiss/tablehdc.htm

    Combined with this:
    http://www.442.com/oldsfaq/oldsfaq.htm

    And having AMA specifications + some car life magazine road tests on hand are enough information to run engine dyno software with some accuracy for upgrade parts.

    I did made improvements to Fairlane too as I managed to find 1966 road test for that car, I found out that after market rear springs are ~22000 when Ford's factory data given to magazine told it was ~18000, also got spring rate for the front too there and other nice bits.

    Those old road tests are really incredible, especially those in car life, which probably never was available here. Would love to have all car life numbers having road tests cars we are making, but not so sure if can be found and especially at any price I can afford.
    Anyway, cool thing about those road test is that they have air resistance data also, they have coast down tests done, so I can input time and speed into my formulas and get drag, how neat is that?
    Also there are information about camshaft IVO, IVC, EVO, EVC etc. So it makes it possible to use dyno software to get close to reality results for engine.
    For brakes, they don't say only diameter, but also width, line pressure for known pedal pressure and fading, it is like they had done those test for a modder back in 60's :D

    So road test articles of Car Life magazine are something that I could really use along with measurements of the cars.

    http://wildaboutcarsonline.com/cgi-bin/pub9990262549620.cgi?categoryid=9990262549620
     
  18. martymoose

    martymoose Registered

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    The view must be horrible from the cockpit Im surprised he can even see the track lol.

    Regarding your issues with tyres could it be more to do with the track then anything else, A drag strip is pretty much made of rubber so you'd need to find a way to pre rubber it to the max before the start of the session. If going into drag strips it would be great to be able to make tracks with different amounts of rubber built in as the green level, as Im sure they must all differ quite a bit in real life. I wouldn't expect it to rubber down much more in a race weekend but I dont know much about drag racing so Im only thinking out loud. All the older tracks do appear to have huge amounts of rubber down on them at all times and from seeing it on tv I dont see it changing much from the start to end of a weekend but maybe it does still. I assume its just temperature and weather conditions in general that change throughout and not the extra rubber from a few hundred runs over a weekend.

    Sure the rear tyres are huge but give the real drag cars a green track and they would be a complete pig compared to a well rubbered track would they not?
     
  19. jtbo

    jtbo Registered

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    One drag racer told me that if shoe laces are not tight, shoes get stuck to track when walking at start area, with glued track and well warmed tires, over 800hp is not enough to brake traction at launch.

    Then around 1000hp on street (that is what the guy says):



    Here in Finland our drag tracks are covered by ice and snow during the winter, during the summer grip however builds up and our events are relatively small compared to for example US.

    Then I did read old magazine article, from link I posted earlier, it was 350 olds motor in 1968 Oldsmobile if my memory is correct. However with street tires they had to feather the throttle at strip with launch rpm of around 1200, they put cheater slicks on and stalled it at launch, with 5000 rpm and sidestepping a clutch it barely managed to get going, motor had no more than 6000rpm if I remember correctly, so that is how much there is difference in traction with slicks and street tires of late 60's when track is not dusty like city street on those Nelson's videos, I have impression that dust effects a lot to slick tire. I don't know if we have dust in rF2.

    Anyway at Mills pit garage has a lot more grip than track, then if one manages to go over the guardrail, between track and pitlane, there is absolute 0 grip, car slides with constant velocity at least 10 minutes, bouncing off from walls, yeah, so because there is higher grip I have tested hard launches there in a garage and bucket does a wheelie with BT20 tires, which are rather grippy in that car, I would say close to slicks in terms of grip. Still needed really strong motor (I used actually Ford 302 trans-am race motor build to make one), also weight distribution needed to be close to 70% back and there was then bit of grip issues too.

    Might be partly because of quite stiff front suspension, softer suspension might make lifting front easier, but with current limitations to only a-arm front suspensions it would look quite silly to have solid beam axle flexing from middle.

    I still need to do reading about drag slicks and how those are constructed and then build ones to start having experiments with those, one thing I wonder if engine does support tre twist that can be seen at some slowmotion drag launch videos, but we will see that when I get around to build those tires.

    I have been enjoying myself with this wealth of engine data I have found and I have build many engines with help of engine dyno software, it is surprisingly close to real power levels when you get precisely correct data for it, but still it does lack some things, no curve below 2000rpm, low end torque is often too much, rpm resolution is only 500 and it is really easy to get completely wrong results, also often I need to play with cam timing to have peaks at correct spots, so it is far from perfect, but better than no torque curve at all. Also upgrades are much easier to get somewhere on correct range when you get base motor close.
     
  20. Gearjammer

    Gearjammer Registered

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    Have you looked at NHRA rules and regulations for engine specs? I believe Super Stock or Pro Stock has the specs as detailed to them from the manufacturers and has been a highly contested group. Very close racing when everyone blueprints the engines to the same specs. Basically though, you are looking for the blueprint specs for the engines so you have a base spec that you can work off of. These specs include bore, stroke, cc volume of heads, flow data, compression ratio, cam timing and a wealth of other data. I will see if I can find links for what I am talking about.

    Ah yes, here you go: http://www.nhra.net/tech_specs/engine/

    Keep in mind that when you blueprint an engine you are usually going to end up with more horsepower and torque than what has been advertised mainly due to the manufacturer's playing games. The EPA imposed restrictions on vehicles at different times for different reasons. Because of this, auto makers would lie about what the engines were capable of in order to comply with the regulations that were put to them. For instance, in the late 50's, engines were not allowed to exceed 500 cubic inches, so when Ford put out a 507Ci engine, they advertised it at 490.
     

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