Dan Baldwin
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Posts posted by Dan Baldwin
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I bought mine new from Nissan last year. They aren't "curved", but the lugs for mounting the brake caliper are offset maybe 1/2" from the part that bolts to the hub.
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What's your intended usage? For a street driven L24, I'd go with the E31. It should give you ~9.1:1 compression ratio. The N42 would give you bigger valves, but CR would be more like 8.8:1. Also the N47 would require a different exhaust manifold/header, for its round exhaust ports.
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Too long, where'd you hear that? Use the later ('72+?, '73 only?) L24 rods with 9mm bolts. Do NOT use L28 rods (too short) or L20 rods (too long).
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It's rich in the mid-range. Causes that big dip right around 4500. Dunno what to do 'bout that. I gained 5 lb-ft from 4500 up (still with the dip, though) since that dyno run by installing smaller air jets in the carbs to keep it from leaning out up top. Did that on a different dyno and pulled 228hp before and 233hp after the jet swappage.
$16/hp isn't bad at all for a moron like myself (albeit with excellent technical advisors). Lot's of folks spend $100s for little to no hp!
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Oh yeah, total cost was ~$4500 for the motor and ancillaries. Go here: http://www.hybridz.org/ubb/ultimatebb.php?ubb=get_topic;f=12;t=000867#000004
for a summary of costs.
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235 rear wheel hp dyno results here: http://www.classiczcars.com/photopost/showphoto.php?photo=2274&papass=&sort=1Originally posted by Tony Fruzza:I would be interested in seeing engine bay photos, and dyno sheets. Also would be intereseted to hear just how much a built NA L series would cost.
I've seen quite a bit of NA guys saying they are making lots of power, but have rarely seen dyno sheets. Please enlighten me.
The motor is an NA 3.1 liter built WAY back in '94. Early this year Sunbelt did some headwork and installed a cam that allows use of light springs. I put a set of used 45mm 3X2 OER Racing carbs on it a few months ago, and took it to the dyno the next day, and that's what I got!
The motor isn't the best street motor, but it was before I cammed it to get better high-rpm power. I guess 235 rwhp should translate to 275 at the flywheel, but I've also heard that rear-wheel inertial dynos are a bit optimistic.
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For 99.8% street usage, I'd go with the Bridgestone S03s. Not because of wear or durability concerns, but because I *think* that for street usage (tires not as hot as they would be after a few corners at the track) they might actually give better grip than the DOT race rubber.
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Oh yeah, a little anecdotal evidence of the above. Last year at New Hampshire Int'l, road course/south oval configuration, during a wet session I was faster than a somewhat competently driven M3 on Kumhos, in my '91 240SX on Bridgestone RE730s! Every lap he'd gap me, but I'd be right on his tail by the exit of the big oval turn. Then he'd pull away again through the rest of the course. That more than anything convinced me to buy STREET tires (Bridgestone S03s) for my 240Z for wet track duty and street driving (Hoosier R3S03s for dry track usage). I had been considering unshaved Kumhos. Now, though, I just don't think the DOT race tires could get warm enough to stick as well as the best street tires in the wet.
Like I said, though, purely anecdotal, could've been the M3 was timid on the oval.
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Pete, wouldn't you be much better off with BFG or Nitto Drag Radials than with stiff-sidewall road-race/autoX tires if launch traction is your main concern?
babykyle, the 280Z (not ZX) looks almost just like a 240z, but with much larger bumpers. The ones on the 240Z are much smaller and lighter. The 280Z is fuel injected, while the 240 has dual Hitachi SU carburetors. The brakes and suspension setups are similar between the two, with minor differences that (I think) prevent spring swapping between them.
As for DOT race tires on the street, the Hoosiers are generally considered too fragile. A recent Grassroots Motorsports article had the Toyo RA-1s a little slower around an autoX course than the Kumho Ecsta V700 and the Kumho V700 Victoracer. With two different test drivers, one was faster on the Ecstas and the other faster on the Victoracers. Both drivers were quickest with Hoosier A3S03s, and slowest with the RA-1s (not by a whole lot). I've known guys to drive over 400 miles to events on the Victoracers, so I guess they're somewhat streetable. The DOT race tires were on the order of 2 seconds quicker around a 40 second course than the Falken Azenis or BFG KD street tires, pretty significant. Throw moisture or cold temps into the equation, though, and the best street tires might be better than DOT race tires, though.
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As katman knows (and has been responsible for), 240Zs can still be competitive in SCCA competition against more powerful modern machinery with better brakes. 280Zs are less competitive due to carrying ~400 lb. more weight. Still, you should be able to make it corner with the best modern street cars with a little effort. Ditto what katman said regarding springs/dampers. 225 tire width is not a problem with the stock wheelwells. This means that despite being heavier than a 240, you've still got potential for bigger tire width relative to car weight than just about any modern car. There are quite a few max performance tires available in 225/50-15, which won't rub much if any on zero offset wheels. If you're up to it, you might also consider ways to increase negative camber. The cheap and ugly way is to slot the shock towers, which would get you around 1/2 degree more negative camber. Something like -1.25 front and -1.75 rear would likely be a good streetable setup for maximum handling.
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Mike:
"some of you guys are forgetting wht this new Z is the way it is.. they are trying to bring it back to its old roots."
That was the IDEA. Nissan didn't even come close, though.
Mike:
"Now i know the old 240Z was a car with no nothing and weight was nothing to, but rememeber this is the year 2002, car makers have big standards to stick to, they need all that crap that makes it heavy so they can sell the car in the 1st place."
BS. Mazda doesn't seem to be having too much difficulty selling 2300 lb. Miatae (though Toyota isn't having quite as much success with its 2200 lb. but ugly MR2 Spyder). That's what the new Z shoulda been, a 6-cylinder Miata coupe, basically.
Mike:
"this Z is everything the old 240Z was and more"
You got that right, MORE. Like, 1000 lb. MORE. I was hoping for a lot LESS.
Mike:
" I wouldnt care if the Z06 was 35k, i wouldnt drive it, it doesnt have that feeling that all Z owners have known to love, plus to my eyes its a RWD Sunfire, plus there ugly and ALL U SEE IS C5's...... hell i see about 4 Z06's everyday in my town."
Well, if you don't care too much about having a fast, trackworthy car, I can see how the Z06 wouldn't interest you. It isn't all that attractive, to be sure, but I do find it better-looking than the 350Z.
Mike:
"And who ever said that the Z28 would out handle a mustang is false, read some mags, the GT was slower but out handled the Z28 and SS."
The F-bodies handle a lot better than the Mustangs, to the point that the FStock SCCA AutoX class they share is pretty much F-body only. Mustangs have no prayer against them.
Mike:
"and GReddy already has a Twin turbo kit for the 350Z, twin 18g's!!!!!!!!!!!!!! CRAZY HP.
I want a car that is fast by virtue of being lightweight and elemental. Like the 240Z.
Unfortunately for me, most people would rather have 50% more power than 33% less weight.
So we get the 350Z. The Solstice is on the way, though! I will have one (unless I get rich enough in the meantime to get a Lotus Elise).
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They shouldn't have put it on the FM platform. It's just fine as a luxury/sport sedan and coupe, but for a Z it's far too heavy. Electric windows don't add much if any weight (years ago the lightweight Porsche RS America came with electrics only because they were LIGHTER!). Power seats are an option, anyway, right? Power door locks weigh next to nothing. They SHOULD have made, basically, a Miata coupe with the VQ engine. That would've been a killer new Z. Tiburon's lines aren't bad at all, but it's got a face only a mother could love, and of course it's heavy, and wrong-wheel-drive. The Mustang is a bit much. IMO, Ford went down the wrong path with the big, heavy DOHC engines. Two of them in my time-trialing club blew up last year. I'd much rather have a smaller, lighter, lower c.g. LS1 (or LS6!).
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A Mach 1 Mustang outaccelerated the 350Z in a Car and Driver comparison. The 350Z was faster around a race track, though (faster than an S2000, too!). NLA, but a stock Z28 is MUCH quicker than the 350Z. A friend of mine bought one a couple of months ago, put down 308 rwhp, and did 13.4 in the 1/4 at 106mph. ZERO mods. On all-season tires. Oh yeah, sticker was $24,XXX, and he paid $21,000. Z28s are well known to be better-handling cars than Mustangs. My money would be on an LS1 Z28 over a 350Z at the drags, autoX, and road course. I still don't understand how that much performance for that little money could go ignored.
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I can't believe this hasn't come up yet. Here's why the 350Z sux. WEIGHT. At 3300 lb. it is WAY overweight. It doesn't need more power, it needed to come in at more like 2600 lb, 2800 MAX. If they wanted to make another ZX for me to ignore, fine. I do wish they hadn't gotten my attention with all the talk about the new car returning to the original Z ideals. Complete BS.
Hyundai Tiburon? What's an overweight fwd not-very-sporting coupe even DOING in this thread?
I'm holding out for a Pontiac Solstice, the REAL new Z.
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The tires you mention aren't really high-performance tires. Do you really need all-season tires? Even if you do, there are better all-season performance tires. As Mike said, AVS Intermediates are good, and cheap on closeout from the TireRack. I got a set for my 240SX. Those and the Yok AVS100s are the only real performance tires in 205/60-15. You get a bigger selection in 205/55-15. Bridgestone RE730s are good (had a set on my 240SX, did great at the track(road course)), and Bridgestone S03s are excellent (have 'em on my Z for road/wet track usage). For serious performance, you will give up tread life. Compare the UTQG ratings, higher implies greater tire life. Go to www.tirerack.com and compare away.
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Well I'm pretty DANG sure the opposite is true:)
Sorta counterintuitive, but increasing track at one end of the car will increase the outside tire loading at that end of the car, and reduce it at the other end. Cornering speed would go up, but the car would tend toward sliding the end where the track was increased first. Kart racers can slide their rear wheels inboard or outboard on the axle, and move them inboard to increase grip at the rear (reduced oversteer) and move them outboard to increase grip at the front (reduced understeer).
Either way, the effect of increasing track only (no camber or toe changes) on a Z by 1/2" shouldn't have a significant effect on overall balance.
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I'm pretty sure increasing front track will INcrease understeer, as it increases the lateral load transfer at the front relative to the rear.
In any case, I think zcarbum wants to use spacers to fit fwd-offset wheels, not necessarily to increase front track.
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Whoops, I blew it. His equation DOES match mine. I thought the cos2(O) in his eqn was cosine of theta SQUARED instead of cosine of twice theta. My bad. It certainly is a much tidier equation, guess I've got some cleaning up to do.
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That equation gives the correct piston accelerations at TDC and BDC, but it is incorrect elsewhere. It misses the maximum upward piston acceleration that occurs before and after BDC. I'd bet money (if not my Z) on my equations. I'll send a plot of that equation along with mine in the spreadsheet I'm sending you.
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What Jim said.
The equations work with whatever length units you want to use, you just have to be CONSISTENT. If you want feet/second, input stroke and rod length in FEET.
If anybody wants my spreadsheet, I could email it to ya.
Dan
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At COMSCC time trials yesterday, I set the official fast time of the day! First time that's happened. I drank a beer out of the trophy, and damn it was sweet. Beat a bunch of Cobra replicas, Z06 and other C5 Corvettes, Porsches, GT-2(3?) RX-7, Formula Ford, etc. There was a Formula Continental that was faster than me, and he and I both caught the guys in front of us in our timed runs. When that happens, you can either accept the laps you've done, or throw them out and rerun. We both chose to rerun, but he decided to leave early and didn't do it, but his initial times had been thrown out. I'll take it anyway! Ran a 1:02.49 on my third timed lap. Woohoo!
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Maybe I shouldn't have worded it exactly like that. What I meant is that you can't take a value in units of length/time (speed) and "convert" it into a length/time^2 (acceleration) value, just like you can't convert linear feet into acres (the question "How many feet of land is your house on" has no meaning). You CAN, however, derive equations for speed and acceleration if you have an equation for position, which isn't too hard to come up with for piston motion. You do have to have to perform derivative calculus, though. Take the derivative of the equation for position with respect to time, and you get the equation for speed. Then take the derivative of the equation for speed to get the equation for acceleration.Originally posted by Dan Baldwin:mph, ft/s, are in units of SPEED (distance/time). ft/sec^2 and g are in units of ACCELERATION (distance/time^2). There is and can be no conversion.
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Kevin, it's not your formula for acceleration that's wrong, it's your definition of variable "A". Should be stroke/rodlength. Peak piston acceleration is AT TDC. 2nd time, acceleration and speed are different, you can't convert one to the other. Peak SPEED occurs at ZERO ACCELERATION, and vice versa. mph, ft/s, are in units of SPEED (distance/time). ft/sec^2 and g are in units of ACCELERATION (distance/time^2). There is and can be no conversion.
Jim, check post #2 for the equations of motion for the piston.
Michael, I'll go through my calcs again, but I think they're alright. Good points on the local extrema. Most people would think BDC should be the location of maximum upward piston acceleration, but it's not, that would be at 145 ATDC and 215 for my engine (apparently 135 and 225 for yours). Acceleration at BDC is actually a local minimum, which may come as no surprise to anyone who's observed piston motion as an engine is turned over. The conrod "standing up" increases piston acceleration at TDC, but reduces it at BDC, to the extent that for my engine the maximum upward acceleration near BDC is only 55% of the maximum downward acceleration at TDC.
Interesting stuff, no?
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OK, I found the problem. You list your variable "A" as connecting rod length to stroke ratio. It should the the inverse, stroke/conrod length.
LT-5 Info?
in Gen I & II Chevy V8 Tech Board
Posted
No Corvette ever had a 305 other than prototypes and test mules. The LT-5 is around 350 c.i. Visually a totally different powerplant than the 305/350. Wonder if this is the same guy with the 8-rotor NASCAR motor in his Eclipse?