Searchy Posted January 31, 2008 Share Posted January 31, 2008 That crank pully at 11" is I believe about the same distance that a SBC has, Actually, a SBC is about 7 1/2". That hole is getting awfully deep Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted January 31, 2008 Share Posted January 31, 2008 Actually, a SBC is about 7 1/2". That hole is getting awfully deep So if that were true, which I think it is higher myself to the bottom of the sump, not just the front of the pan, that means the the Scooby engine is then mounted higher than the SBC, in relation to the crank center line, and having even less "lowering of the center of mass" It may even end up at the same hight as other engines. Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted January 31, 2008 Share Posted January 31, 2008 Please for the love of god lock this thread already. lol Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 31, 2008 Administrators Share Posted January 31, 2008 Six, You mention one aspect then spin it to another. Are you coming or going? Are we discussing Subaru powered drag cars of the ’50’s, stadium truck racing, front wheel drive pull toys, or attempting to utilize a Subaru engine in a front engine rear wheel drive sports car, that also turns corners as well as cruise the mall parking lot? I’m lost… If the Suby engine was bolted to the Datsun tranny, the crank centerline of the Suby would be the SAME as the crank centerline of the L-6, unless we raised the tranny for some other application such as a Z car rock crawler. I am pretty sure the SBC JTR conversion places the SBC crank centerline at approx the same elevation in the car as the L-6. As such, the Center of Mass of the Suby would be at least 5” lower than that of the SBC conversions and L-6. ….. I have quite a bit of experiance with this and quite a bit of theory study as well. I don't say something unless I'm sure of what I'm saying…. If you indeed do have actual experience and credible knowledge in this field, you really need to qualify your statements a LOT better and more thoroughly than you have been. Reading your posts is like trying to find sunken treasure toys in muddy water. ….. You're also misconstruding what I am saying, take that 911 and take off most of the front weight, it won't handle well without good front grip, …. Yeah, it’s pretty easy to misconstrue one thing when you come back and post a different topic or direction. Again, you need to qualify your statements more thoroughly! F1 teams spend millions to build a car that is lighter than the rules permit... so they can attach ballast to the bottom of the car, i.e. lower CG!... Ah forget it. Those actually in the know with actual first hand experience already know better. Please either qualify your “knowledgeable” statements more thoroughly or quit muddying the waters as it confuses not only the newbie’s, but is obnoxious for those wanting to further their understanding of how and why cars do what they do… When you finally catch your tail, let us know, ok? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 31, 2008 Share Posted January 31, 2008 Why are you talking about cars, like the subie and the Z? My question is physics related, and physics alone. Tell me, how on earth does moving weight backwards remove traction up front. I'm not saying you're wrong, but I won't believe you until there's some equation with theory to back it up. Here's a bit from "Tune to Win" that explains why vertical load (weight or aero) is necessary for traction: A tire's coefficient of friction decreases slightly with increasing vertical load. However, up to the design limit of the tire, its traction capacity, its ability to actually transmit force to the road, as opposed to its dimensionless coefficient of friction, increases with vertical load. This apparent contradiction works like this: As the vertical load on a given tire increases, the area of the rolling contact patch remains virtually constant, and so the unit pressure of the footprint must increase. As the unit loading rises the rubber has less resistance to frictional shearing and so the coefficient decreases... However the curve is so gentle that the increase in vertical load overpowers the decrease in coefficient. The result is a curve of increasing traction either transverse or fore and aft with increasing vertical load. It goes on from there, and the book is worth reading. The point is you do need some weight on the tires to turn the car, but Z cars have more than enough weight on them to turn, so we're generally trying to make them lighter and reduce weight transfer to keep that weight on the inside or rear tires depending on whether we're turning or braking so that they can contribute a larger percentage of the work to the whole. As Smith says on the next page: So either lateral or longitudinal load transfer will always increase the traction capability of the more heavily laden tire or pair of tires. Lateral load transfer between a pair of tires will, however, always result in a decrease in the capacity of the pair. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted January 31, 2008 Administrators Share Posted January 31, 2008 Actually, a SBC is about 7 1/2". That hole is getting awfully deep So if that were true, which I think it is higher myself to the bottom of the sump, not just the front of the pan... If you indeed do have actual experience and credible knowledge in this field, you really need to qualify your statements a LOT better than you have. That is precisely the problem, Six... your statements are a bit empty. We'd all be happy to entertain your thoughts, but you need to give us some firm ground. Quote Link to comment Share on other sites More sharing options...
Gollum Posted January 31, 2008 Share Posted January 31, 2008 Here's a bit from "Tune to Win" that explains why vertical load (weight or aero) is necessary for traction: I've really been meaning to buy that book. Honest. I'm just still completely drawn to this book any time I get the chance. http://www.amazon.com/Modify-Management-Systems-Motorbooks-Workshop/dp/0760315825 I'll have read that book cover to cover several times before feeling confident in what I've learned from it. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 31, 2008 Share Posted January 31, 2008 Tune to Win has very little to do with engines and EFI, by the way. It's chassis tuning mostly, with some aero as well. Just FYI, not sure if you thought it was about EFI because of the title... Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted January 31, 2008 Share Posted January 31, 2008 Haven't seen that myself in probably close to one hundred autoxes. Maybe you could give me an example. Nope, I would have to find video or something of that nature, and there's more racing than auto-x. Auto-x is usally on very tight courses where even the "Sweepers" are very tight. Suffice it to say that everyone's driving style is a bit different and some prefer to not mash the brakes to turn. So you're saying that ON THE STREET there is a car that has so much rear weight bias and so little weight transfer that you need to step on the brakes to get the car to turn? Again, never seen it. Do you have an example of this? Look farther down in your own post, there's one a 911, where evn you say that you needed lots of camber to get them to turn. I'm talking about spirited driving here, because it's pretty obvious that driving even a poorly set-up car at regular speeds will still turn. It seems that some of us already have. Well, not rear engined, but rear biased. It isn't done just to improve the braking though. It also improves traction coming out of the corner. By how much? 55% 60% 80%. Yes it will improve traction of the rear wheels out of a corner, that's been established and agree, but if there isn't enough traction on the front wheels then it will easy turn into a push situation, more noticed on higher power cars. If you were to say that with the stock power of the Scooby engine that wouldn't be much of an issue, I would agree, but who's going to swap an engine like that without getting more power out of it. Can you give me an example HOW other areas might suffer? An improvement in braking could reduce steering responce, Improving downforce could reduce accleration or top speed, improving steering responce could reduce braking stability, straight line accel among many others and instances. Chassis set-up is all about compromise, there's not one perfect set-up, if there was, there would no longer really be any competition as everyone would be using it. The changes that affect other areas are never an absolute, but possibilities, and what is changed in one area can effect different areas differently, hense why there is constant tuning and changing of items and adjustments. I used to be a Porsche mechanic, and my boss raced and quite a few of our customers raced so I was involved with setting up a number of them for racing, corner weighting, alignments, etc. I never saw or heard of any of them fixing a push by stepping on the brake. We used to put a hell of a lot of caster into the 911s though. 911's do require careful throttle modulation because of their rear weight bias and even more so on the older ones with the semi-trailing arm rear suspension. Youv'e NEVER tapped the brakes to get the weight to transfer forward to get more bite? Weight transfer is weight transfer whether it be lateral or longitudinal. When you step on the brakes, it's longitudinal. Well since we're on a Z forum, let's apply these ideas to that platform and suspension. Remember that the wider rear tire thing was a response to you saying that you'd need a wider front tire to get more traction if you had less weight transfer to the front (which again doesn't make too much sense). Do this: Hold your hand above the table, place just your index finger on the table, now without applying doward force move you hand sideways, I know this is a bit subjective here, but feel how much resistance there is to yoru hand moving, or how much effort you need to apply to move you arm/hand sideways. Now, place all 4 fingers on the table and see how much force you need. If wider tires had no benefit to adding grip then we'd all be running much more narrow tires. In some of the racing I get involved with, which is mostly drag (It's what I've grown up around but do try and involve myself or at least keep an eye on other forms of racing), the lighter cars need the wider or gripier tires to get down the track. The heavier cars have the ability to plant a smaller or less grippy tire with more weight over it, hence weight transfer being good. I don't see why this is such a hard thing to understand. Quote Link to comment Share on other sites More sharing options...
G.I.jonas Posted January 31, 2008 Share Posted January 31, 2008 This is way out of hand,this seems like 3 threads in one.The most dominant being weight transfer and chassis physics that seem like they could be usefull elsewhere other than here? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 31, 2008 Administrators Share Posted January 31, 2008 ….I have quite a bit of experiance with this and quite a bit of theory study as well. I don't say something unless I'm sure of what I'm saying. Your posts thus far are painting a different picture… …. You're also misconstruding what I am saying, Please help me not misconstrue your point here… I understand that, but part of the discussion was also about mounting the engine lower by mating the Scooby engine to a convention RWD tranny, which is not the case, or at least not the 4" that Braaap believed could be done. Using your experience and theory study, please explain to us how you could possibly mate an engine to a transmission and have its crankshaft centerline be at a different elevation than the engine that used to bolt to that same transmission? Ill be more specific. Lets use the Datsun transmission, bolt a Suby engine to that transmission. Now how on Gods green earth are you going to get the Suby crank centerline to be at a different elevation than what the Datsun crank centerline was? Have you separated an engine from a transmission before? You do relaize that the crank centerline MUST be dead centerline with the transmission input center line. The only way the crank centerline would change in elevation is if you altered the actual transmission elevation! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 31, 2008 Share Posted January 31, 2008 In some of the racing I get involved with, which is mostly drag (It's what I've grown up around but do try and involve myself or at least keep an eye on other forms of racing), the lighter cars need the wider or gripier tires to get down the track. The heavier cars have the ability to plant a smaller or less grippy tire with more weight over it, hence weight transfer being good. I don't see why this is such a hard thing to understand. AHA!!! This is why you're notions about road racing don't make sense. You're a drag racer!!! Weight transfer is good on a drag racer because you only accelerate the car in only one direction. You want as close to 100% weight transfer on the rear wheels as possible, because as Carroll Smith says, the more vertical load on the tires the more traction is available TO THAT PAIR OF TIRES. Only the tires providing the acceleration matter in drag racing, and even in a AWD the rear tires are MUCH more important than the front tires because of the rearward weight transfer when you launch. Road racing is NOT drag racing. You need ALL the tires to do something when you're road racing. If you have 100% weight transfer to the rear, you can't steer with the front. If you have 100% weight transfer to the right, the left side tires can't turn or brake. If you have 100% weight transfer to the front, the rear can't provide any directional stability to keep the back end in line. And above and beyond all that, Caroll Smith's axiom about weight transfer is true all the time: "...load transfer between a pair of tires reduces the capacity of that pair." So any time you have weight transfer the total capacity for traction goes DOWN. It just doesn't matter on your drag cars. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted January 31, 2008 Share Posted January 31, 2008 That is precisely the problem, Six... your statements are a bit empty. We'd all be happy to entertain your thoughts, but you need to give us some firm ground. Cool it's been a while since I've played with a SBC, and realize that I was thinking more of the deep sump pans than the stockers. But the fact still remains that the Scooby engine in question has 11" between the crank center line and the bottom of the stock oil pan. I don't know if the Scooby pan can use a short sump or not, if it can, then yes the center of mass could be lowered, if not that it would have to remain in this example 3 and a half inches higher than an L6 or SBC, due to ground clearance of the oil pan. I can see where you're coming from, as far as needing to back statements up, but this stuff isn't new, I've been reading and experiancing it for a number of years. If I wanted to I could go through a few books I have, and quote them, but most have either been borrowed books, magazines that have been long thrown out, or talking with people I know that are very into chassis design, besides the things I have tried, not all have worked, and have been told that some shouldn't work, but have worked for me. Like very stiff sway bars that I was told would make the car "skip" accross the road surface, when it actually made my car at the time, though still ill-handling (it was a FWD, I hate FWD) in my eyes much more predictable, and easier for ME to put through a corner. Now many people are actually making almost solid (as in very little twist) sway bars and anti-roll bars. I just find it very odd that people here have "experianced" or read differently. Quote Link to comment Share on other sites More sharing options...
G.I.jonas Posted January 31, 2008 Share Posted January 31, 2008 The only way the crank centerline would change in elevation is if you altered the actual transmission elevation! Not true,just use some sweedish engineering and connect the crank to the clutch via chain and sprocket or gearset. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted January 31, 2008 Share Posted January 31, 2008 AHA!!! This is why you're notions about road racing don't make sense. You're a drag racer!!! Weight transfer is good on a drag racer because you only accelerate the car in only one direction. You want as close to 100% weight transfer on the rear wheels as possible, because as Carroll Smith says, the more vertical load on the tires the more traction is available TO THAT PAIR OF TIRES. Only the tires providing the acceleration matter in drag racing, and even in a AWD the rear tires are MUCH more important than the front tires because of the rearward weight transfer when you launch. Road racing is NOT drag racing. You need ALL the tires to do something when you're road racing. If you have 100% weight transfer to the rear, you can't steer with the front. If you have 100% weight transfer to the right, the left side tires can't turn or brake. If you have 100% weight transfer to the front, the rear can't provide any directional stability to keep the back end in line. And above and beyond all that, Caroll Smith's axiom about weight transfer is true all the time: "...load transfer between a pair of tires reduces the capacity of that pair." So any time you have weight transfer the total capacity for traction goes DOWN. It just doesn't matter on your drag cars. Yes, I have read about the circle of traction, and have found it to be very useful. You need to look a bit more into drag racing, it's not all about "point and shoot". You'd be amazing at what is really going on with the driver down a single digit 1/4 mile sprint. Besides that's not all I'm into, I just have a majority of my (racing) experiance there. I tend to turn more often than I drive straight though, and although less in the past few years I tend to drive fairly spirted at times, and enjoy the turns more than the straights, and have modified my cars to work better around cars than in a straight line. I plan to change that with the S30, I'm trying to acheive at least a bit of both. Which is why I'm debating between keeping the IRS or going ahead with the live axle swap, I've seen live axles work well for both. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted January 31, 2008 Share Posted January 31, 2008 Your posts thus far are painting a different picture… Please help me not misconstrue your point here… Using your experience and theory study, please explain to us how you could possibly mate an engine to a transmission and have its crankshaft centerline be at a different elevation than the engine that used to bolt to that same transmission? Ill be more specific. Lets use the Datsun transmission, bolt a Suby engine to that transmission. Now how on Gods green earth are you going to get the Suby crank centerline to be at a different elevation than what the Datsun crank centerline was? Have you separated an engine from a transmission before? You do relaize that the crank centerline MUST be dead centerline with the transmission input center line. The only way the crank centerline would change in elevation is if you altered the actual transmission elevation! Simple, two words: Ground Clearance. Yes, that's been my point all along that the crank CL and input shaft CL have to be inline. So looking at the pics in this thread of the Scooby flat 4 and the SBC oil pan, that means that the tranny needs to be raised to have everything lined up. I was actually surprised at that myself, I thought the crank centerlines in relation to the oil pan bottom would have been closer. Quote Link to comment Share on other sites More sharing options...
G.I.jonas Posted January 31, 2008 Share Posted January 31, 2008 noooooo!!!!! no more pissing contest - you guys could have contributed so much meaningfull info by now with a little focus. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 31, 2008 Share Posted January 31, 2008 noooooo!!!!! no more pissing contest - you guys could have contributed so much meaningfull info by now with a little focus. I kinda feel like we're making progress here. We may not be learning much about transplanting Subaru engines in Z's yet, but I think if he's not totally close-minded he should be learning quite a bit. If you want to talk about cutting up the frame rails to redirect the conversation go for it. Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted January 31, 2008 Share Posted January 31, 2008 noooooo!!!!! no more pissing contest - you guys could have contributed so much meaningfull info by now with a little focus. I'm only going to post once on this thread... My hair is hurting reading thru this whole thread.... :eek2: LARRY Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 31, 2008 Administrators Share Posted January 31, 2008 noooooo!!!!! no more pissing contest - you guys could have contributed so much meaningfull info by now with a little focus. Sorry fella’s. I take responsibility for this. I was feeling like I was pulling wisdom teeth just to get some clarification and qualification to some key points. At some point, the pain of beating my head, overwhelmed rational judgment. Please accept my apology. Sorry guys. Jon has this one very much under control. Good night, Paul Quote Link to comment Share on other sites More sharing options...
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