X64v
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Posts posted by X64v
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Thank you guys, that answers my question.
jmortensen - Yes, I agree that the stock cams are puny. I'm looking at a regrind (specifically a .495"/290°), but could only find info on how it would perform on an L28 with regards to drive-ability, useful powerband, etc. Since this is going on an N/A L24, I wanted to make sure that a .495/290 on an L24 would act the same as a .495/290 on an L28 (come in at the same rpm and all that).
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I've finally grown tired of beating my L24 to hell with a turbo (it was fun, but I really don't need to sink any ring lands in my daily driver during my first year of college), so while I build a proper L28et, I thought I'd at least throw a cam in the E31 I have laying around to get a little pep back. My question: With comparably dressed L24/28s (same headers, induction, SCRs), how do cams sized for an L28 with it's bigger valves perform on an L24 with it's smaller valves? I would guess that with the valves being smaller along with the decrease in displacement, a cam would feel about the same in both motors, but I want to double check here.
Bottom line: Would the same cam feel 'bigger' on a small valve L24 than a big (normal) valve L28, or would it feel about the same? I'm not really looking for a cam recommendation for my particular set up, just the relation as asked.
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To first order it makes sense. If you double the boost, you double the amount of air/fuel charge being pumped into the cylinders.
Yes, I agree that the ratio is right, but the number that is coming out of that still is not. Atmospheric pressure times boost pressure does not equal a set horsepower addition.
Kevin - I apologize for making my initial response so harsh. I don't mean to be at all, mathematics is a fun thing to play around with and I like testing out theories as well. Just simply saying that this will not work for all cases, it only seems to work in the narrow horsepower band (400-650) that you tested it out in.
An example of how numbers can seem to work out, but not actually mean anything at all: Take your waste size in inches and multiply by your height in feet. For me, that makes 168. Could that be my weight in pounds? Sure, and it might work for a few cases, but by no means does one calculate weight that way.
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I don't see how any of that math is based in reality whatsoever, especially where you account for boost. According to your math, a certain boost level will add a certain amount of horsepower on any engine, always, which is obviously incorrect.
Let's just say, for the sake of argument, that your N/A HP calculations are correct (I have no clue if they are or not, but it doesn't matter, they don't factor into your boost calculations at all). So your engine is making 400 hp and you want 500 hp. You say to take the difference (in this case, 100 hp), and then come up with a boost number to make that horsepower. Let's take another example as a test. Say I'm making 5 horsepower on my engine. If I want 155 horsepower, according to your calculator I need 10.2 pounds of boost...
The problem is in multiplying atmospheric pressure by boost pressure and coming up with horsepower. Where did you come up with that one?
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Heh, thanks. Yeah, you don't see the louvers around too much anymore, but I'm so used to them I can't look at my car without them, it's just part of it.
The wheels are old American Racing wheels I believe, 14x7. Good luck finding them, I have no clue if they're in production still or not.
I think my car actually started out as your car is now. Kinda crappy condition, needed pretty much everything worked on, mine wasn't running though, at least you got that. I don't think I've put over $2000 in the whole thing, if you exclude the fuel injection and turbo parts, which weren't needed to get the car driving well.
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WizardBlack, I did not come up with a direct relationship, just took measurements of temperature and noted the pulsewidths needed. I am aware that I made no account for thermal expansion rates or anything of the sort, which is why I simply noted those numbers.
However, since you brought it up, according to nist.gov, the thermal expansion rate of gasoline is .00069/°F, making the expansion with dT=40°F 2.76%. I think I'd need someone like z-ya to come in and explain the effects of small resistance changes on fuel flow and what the ecu does/thinks it's doing. For what it's worth, I'm running low Z injectors with NO resistor pack. V3 megasquirt takes care of that for me. My guess is that it would only slightly change the opening time of the injector (and with injector opening times being variable by only 10% or greater at 1ms, I'm not sure of the impact of injector temp changes on it's function).
Zmanco, I have tried running O2 correction at idle, and it does seem to work, though I was hoping to try something to fix the fuel temp problem rather than just running O2 correction. It can hunt at times with correction on, causing my idle to bounce up and down a little bit. And 15:1 afr would be way too lean for my motor at idle. It seems to lean miss starting at around 14:1, and really really likes about 12.5:1 or so (really really likes meaning highest idle speed and most vacuum).
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I see that you've been looking through the MSA catalog for brake and suspension upgrades. Nothing against MSA, they supply some good parts, but if you really want cost effective upgrades, and some knowledge to boot, take a look at these threads:
jmortensen's brake and suspension FAQs
auxilary's brake upgrade thread has some good info as well
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Also interesting that it's made of crush-bent tubing instead of mandrel bends...
Very ingenious though.
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Xnke, you have misread the information out there. The e88 will cause knock on L28 engines, not your L24. When on an L28, compression can be 10:1 or higher, depending on the specifics, and with it's chamber design, it doesn't seem to do so well.
On an L24, the e88 yields just 8.8:1 CR, which you can happily run on low grade 87 octane all day long without a problem. I run an L24/e88 under 10psi of boost, without an intercooler, on crappy 91 octane, with no knock.
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Clifton, that's on your 7m, right?
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Woops, never did link my other thread in this one.
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Personally I think the first two things that should be addressed on any S30 are brakes and suspension. Adding power is not only a waste but dangerous until you do those two first.
Greg's got it right on. Get that thing handling and stopping correctly before doing anything else. I got my 240 running reliably on SU carbs, did my suspension and brakes (not huge upgrades, just lowered with good bushings, and properly set up stock brakes) and then got into the addiction that is boost. But if you're just looking for a little umph, and not looking to turbocharge the engine anytime in the future, I highly recommend carbs over fuel injection. They're simple, reliable, and they just work. The only reason I went F.I. is to run a turbo.
I think sometimes the big numbers of the turbo crowd can make people overlook the N/A crowd on here. N/A z's can still be fast, and can certainly be a blast to drive. If your goal is not to race or have an über-super-duper fast street machine, but simply to have a fun car to drive, and not have many problems with it or any down time, a nice N/A l28 would certainly be my vote.
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Nope, there isn't really any specific one you need, there are many, many possible ways to trigger MSnS-E. If you've already budgeted for EDIS, do it. I just used the VR dizzy because I had one already, so it was free. I'll be upgrading to EDIS eventually, when I get a chance.
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I used to work at Target, so I'll tell you their secret. No matter what day of the week they get their wii shipments, they hold them locked up in the back room until Sunday morning. Show up at opening time on Sunday morning, and if they have any, they'll be there. If they're not out on the floor, ask the electronics guy/girl, he/she'll get one for you. They usually sold out before about 1pm or 2pm, and through these months I wouldn't be surprised if they sold out well before noon.
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I'm not intercooled at the moment, no. I do plan to be eventually, but with school getting busy I just don't have time.
I'm running 338cc Ford CFI injectors. Some info about them can be found in the sticky at the top of the fuel delivery forum.
I've been running 24-25 degrees of timing at 7psi for a good few months now. 22 degrees seems to be fine at 9psi. I give thanks to Clifton for helping me with my timing maps, I didn't really come up with those numbers on my own. This weekend I'm going to tune a little more and set things around 20-21 degrees at 10psi. If you're wondering how I'm controlling spark, I'm running MSnS-E as in my sig, triggering via an '82 N/A VR dizzy, with mech. and vac. advances welded up tight. Oh, all this on 91 pump gas.
It's a stock 280zxt T3. I have not rebuilt it. I was told it has about 100k miles on it when I bought it. I've put about 5k miles on it No axial play and just a little radial.
My best guesses for whp are 160-170 @7psi, perhaps 180 or so at 10psi. Not staggering numbers, but keep in mind I'm almost half a liter down, and it's a bone stock l24 longblock. And those are guesses, I could be waayy off.
Any other questions about my set up, timing and fuel maps, whatever, ask and ye shall receive.
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I'd totally buy that as a poster, too. Looks great. In my opinion the simplicity of a drawing vs. a photo is an artistic element, not an inaccuracy.
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For what it's worth, I run a turbo on an L24 with an 8.8:1 compression ratio. Original flattop pistons and e88 head. I just megasquirted the engine first, got that running well N/A, and then bolted on the turbo (with all the additional stuff like oil return bung, etc). It really wasn't very hard or very expensive at all. I've got all the responsiveness of the stock motor off boost, with the power on boost. I'm running 9psi at the moment with no problems.
As for cost, the biggest cost to me was megasquirt, but that's only because i needed injectors and the manifold and all that, because the car was carb'd. The actual turbo swap cost me no more than about $250. Sometimes you can find donor 280zxt's for $300 or $400, but I had no way to transport or store a non-running car, and didn't need most of the parts off it anyways.
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Ads and surroundings not work safe, though main content isn't a big harry greased up shirtless dude playing guitar...
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Elastic deformation is like gently squeezing the sides of an aluminum can, the walls move back into shape when you let go.
Plastic deformation is like crushing the same can, it doesn't return to it's original shape, it stays crushed.
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Larry's word is law around here, so I moved this to another thread.
http://forums.hybridz.org/showthread.php?t=127908
As for this thread, back to our 5.126" rods.
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And my next reply:
MASS IS THE ONLY VARIBLE,your freaking nuts man, Look up what a variable means PLEASE, DAMN.
If "MASS IS THE ONLY VARIBLE", and we "Look up what a variable means", then by definition the 1000lb car and 10,000lb car have to accelerate down the track at the same rate. Are you saying they do?
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This is carried over from 1 fast z's dyno thread, to help keep that one on topic. The posts so far, in order:
I think 600hp in s30 is alot easier on the tranny since you are accelerating alot lighter vehicle. So more power is wasted on accelerating the parts then moving the vehicle vs a heavier car.Agreed. F=MA, less mass equals less force. Make the car lighter, makes parts stronger. Sorta like lighter pistons make stronger rods, etc.I politely disagree with the above statements. Force is dictated by the output of the engine, not the mass of the vehicle. Less mass equals less force for a given acceleration, but not for a given engine output. If you put 600ft.lbs. of torque through a tranny, it does not care what it's trying to move. You're not moving as much mass, but you're going to get better acceleration, making the stress on the tranny the same.The lighter pistons analogy is not the same, as acceleration is held constant, dictated mostly by engine rpm.
The point is moot, as you're using that tranny no matter what, but none of us like incorrect information floating around.
No, I dissagree. If you make a car lighter, the DRIVETRAIN COMPONENTS ARE STRONGER, it IS the same as if a lighter piston is on a rod, it makes the rod stronger.You take a car that weighs 10,000 lbs, with 500 torque, and get sticky tires and launch, then take the SAME motor in a car that weighs 1000 lbs, the car that is ligther, will be less force on the drivetrain.
Take a slege hammer, leave it on the ground, then with one arm, take it and as fast as you can swing it 360 degrees over your head.
Then take a tack hammer and to the same thing.
Post your results back when your done with the hammer testing.
Unless the 1000lb car accelerates 10 times as fast as the other car, which I think may have been X64v's point.There is a reason transmissions are rated in torque. Assuming that 100% of the torque is used (and not lost in say, tyre slip > 1), both cars will pop the transmission at the same time.
Dave
Your piston and rod analogy is true, but does not relate in the same way.That car that weighs 1000lbs will accelerate 10x faster than the 10,000lb car, because the force is the same.
The hammer example is the same as the piston and rod thing. You're holding acceleration constant while varying the mass, which varies the force. This is not the same as the two different mass cars with the same force applied. The force on the car (generated by the engine, transmitted through the drivetrain) is the same in both cases. Cut the weight in half and you double the acceleration, not cut the force in half.
Edit: Dave beat me to it.
Take and tie your car to a tree, and if you could have 4 wheel drive and 100% traction, then rev it to 10k and drop the clutch, this simulates if your car weighed TONS, see what happens.Then take that same car and un tie it.
Less FORCE on the trans/diff/axles.
Take a go kart with 500 hp, and all use a small dinky trans, will work fine. Take that same motor and trans, in a 10000 lb car, and see if that trans last.
It all goes back to F=MA. Less mass, less force, I want a scientific/mathmatical equation showing otherwise, untill them, I will create my own equation to show the difference.Ok let me break it downM = weight of car
A = how fast car is accelerating
F = forward force acting on car, and a direct translation of torque produced by the engine and tyre traction.
Let us first off assume tyre traction is perfect (slip ratio = 0), and let us also assume the same engine is being used, thus F is the same.
If you change M, all you are changing is A.
It sounds like you're talking about M `magically' affecting F without a change in A. Show me how that works?
Dave
I may be wrong, but here is how I'm looking at it...if we're talking about breaking transmissions and rear differentials it comes down to shock loading, not a constant force or acceleration.Say that you have a 500 HP engine and you drop the clutch on a 1000 pound car with no tire (or clutch) spin. I think it would be harder on the drivetrain (a bigger shock) to drop 500 HP on a 10,000 pound car under the same conditions.
I think this is basically what Brian is saying...in general lighter is better...less mass to accelerate is less force on the components.
Here is another analogy: Who would win a 400m dash...a fat guy or a skinny guy? lol...if it were a tie, I would think it would be much harder on the fat guy's bones (components) than the skinny guy's bones. Maybe it's not a perfect analogy, but this thread could use some more lightening up!
Somewhat of a good analogy, but if you slowly crept upto full-taught with the rope or whatever you're tying the car to the tree with, and then started a launch with the rope already very tight, the only thing that would happen if you got 100% traction is your clutch would just spin freely after your bumper or tow-hooks took the brunt of the launch along with the tranmission.but your analogy does make sense... but there are way too many variables to tell for real.
not that you're gonna tie this car to a tree anyway, but whatever.
Yes, a shock load, if a roll is done, theres not much difference, thats why you break things on the line at the drag strip and not so much half track, although it can happen.Take a 2000lb z to the track with slicks, then take the same drivetrain with a 3000lb z to the track with slicks, you will be harsher on the 3000lb car off the line, and more likely to break the drivetrain.
I am speaking from first hand experience fellaws. I dont just pull this stuff out of thin air.
Noone is arguing that a heavier car isn't harder on the drivetrain (atleast not me). I am arguing your reasoning. The reason is that the heavier car has more load on the tyres, which makes them less likely to spin, in addition to requiring more torque to move it.Experience is worthless to us here if you can't explain it properly. Noone is going to take your word for it.
Dave
Where, am I talking about tires helix? I am talking MASS, thats always the varible I am talking about.What do I know right. Well Ive always been the one to think and do outside of the box, if not, we wouldnt even have a twin cam L series head to talk about in this dyno thread.But next time you go to the drags, take and put 1000lb's of lead in your spare tire well, and launch your car with 10 inch wide slicks at 8k RPM, lets see if your trans holds up.
But untill then, I will be installing the Z32 transmission, as the Z32's were the heaviest of the z cars untill 96, so nissan but a bigger trans for a reason.
Clifton and I were talking last night, were gonna go back to the dyno before the year is over, I will use the turbos one last time, and see what we get.
As people have said before, no one is doubting that a heavier car will be harder on the drive train. And I certainly am not doubting your expertise, skill, or experience, all of which are clearly far above mine.But F=MA isn't a robust explanation for the higher shock loads. By saying that F increases with M, you assume that A remains constant. This would undermine the advantage of bringing a lighter car to the track.
The force that breaks drivelines isn't the required force to accelerate the car, but the maximum applied torque before the tires lose grip. This is defined not by the weight of the car necessarily but by the weight on the rear tires. The traction of the tires has a positive, but not necessarily 1:1 linear relationship with the weight loading on the them.
Picture a Z with 1000lbs of lead directly on top of or in front of the front axle. It would require no more force for this Z to spin its tires than a standard Z, and thus would be no harder on the drive train.
A Z with 1000lbs directly on the rear axle would have significantly more traction as well as a higher traction to overall weight ratio. As a result the required force to spin the tires would be higher and thus it would be harder on the driveline.
just food for thought....
Where, am I talking about tires helix? I am talking MASS, thats always the varible I am talking about.In chronological order:
You take a car that weighs 10,000 lbs, with 500 torque, and get sticky tires...Take and tie your car to a tree, and if you could have 4 wheel drive and 100% traction...Take a 2000lb z to the track with slicks...Dave
MASS IS THE ONLY VARIBLE,your freaking nuts man, Look up what a variable means PLEASE, DAMN.
Haha.. ok.Meh.. I cbf retyping it when zero summed it up perfectly.
Dave
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Your piston and rod analogy is true, but does not relate in the same way.
That car that weighs 1000lbs will accelerate 10x faster than the 10,000lb car, because the force is the same.
The hammer example is the same as the piston and rod thing. You're holding acceleration constant while varying the mass, which varies the force. This is not the same as the two different mass cars with the same force applied. The force on the car (generated by the engine, transmitted through the drivetrain) is the same in both cases. Cut the weight in half and you double the acceleration, not cut the force in half.
Edit: Dave beat me to it.
Relating cam specs between L28s and L24s
in Nissan L6 Forum
Posted
Ah, I didn't know that about the SCR relating to bottom end performance, thanks! I'll be at about 9.2:1