Daeron
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Posts posted by Daeron
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Knuckle Duster, whats the deal?? Tony is just giving a real-world anecdote to support the mathematic evidence I just posted up..
The ONLY issue inherent in running a twice-pipe exhaust system is a theoretical lack of scavenging caused by FULLY divorced exhaust pipes.. ie, one pipe fed by the front three cylinders, and one pipe fed by the back three. Having a collector/Y-pipe completely integrates the exhaust pulses of all six cylinders, eliminating that issue.
From that point, it is a simple physics excercise in flow capacity and resistance.. Twin pipes offer *slightly* more surface area per cross sectional area, so there is a slightly increased resistance, to be countered by adding cross sectional area. Yes, two 2 inch pipes offer less flow capacity than a single 3"... but there is more difference between one 2.5" and two 2", then there is between two 2" and one 3".
The numerical difference between cross sectional area numbers and circumference numbers (the added resistance from twin 2" as compared to one 3") is a comparison of a square factor to a linear factor.. in other words, a .25 numerical difference in the cross sectional area, is FAR greater than a .25 numerical difference in circumference.
I had typed up a post and was putting the finishing touches on a diagram illustrating the difference between one 3" and twin 2", when a friend called and I was pulled away from my PC. A power outage later, and all was lost.. and I don't feel like going through it again. But in the grand scheme of things, if a single 2 1/2 inch exhaust is a 5, then a single 3" is a 7, a single 4" is a 12.5, and twin 2" is 6.25.
The total circumference of pipe in a single 3" system is about 9.5"; the total circumference on twin 2" is about 12.25". One 2.5" pipe is about 7.9", and a 4" system is 12.6. Again, that similarity in resistance from suface area of pipe is a linear modifier, where the corss sectional area is a square modifier.. so the cross sectional area makes far more difference than the resistance from surface area of tubing. Only if we were dealing with very LOOONG exhaust systems would multiple tubes start becoming a fundamental impedance.
Keep in mind, TonyD was trying to SUPPORT the use of this type of system first and foremost... "twice pipes" are a subject of more misinformed blabber ("It costs you horsepower!!!" Not if done properly, by calculating your pipe sizes correctly) than almost anything else Z-related, and in case you hadn't noticed, our Dear Little Friend has a WHOLE lot of experience with a world of tuning that did not exist in the united states until recently; bascially, until the Internet gave ALL of us normal people the opportunity to chew the fat with people who had been in the Home Islands, and people who had been on top-competing race efforts with these cars, and KNEW how to get 400 hp out of a stock motor by blinking at it the right way.
This isn't random BS; it is logic, supported by mathematics, and backed up by anecdotal evidence. There are many other discussions where these points have been made, by other people.. Recently I have shown up as a voice of summary for alot of those who don't feel like repeating themselves, but what more can you want on a quest for automotive truth? Logic, empirical theory, and anecdotal evidence all support these ideas on exhaust tubing size.. Search in other car forums, search this forum, or, don't, and choose to stay obfuscated, but the Truth Is.
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I might be able to set something up
Oh god no, the shipping for the type of stuff I need would be INSANE and impossible to be worth it; there is a $300 280ZX parts car on craigslist 30 miles from me right now. If I were REALLY interested that would be ample for me.. I'll probably wait until the right 240SX comes around so that I can go for the transmission and rear subframe all at once; make it a serious project, if I do something like that. I really have no clue how far I am going to go in this direction, but I NEED to do something about my rear brakes, and the last pair of wheel cylinders I saw on ebay went for over $150 (70-76 type) so the idea of repairing the stock drums seems right out to me.. I REAAAALLLYY would like to modernize the rear end a bit, but for now I'm just farting with a walkman on
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Paul.......
what IS this CAR?!??!?!? I must know more........
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I think its not a good choice for a turbo. Compression would be too high and needs retrofits for the FI.
With flat tops, yah, compression comes in at 9.4:1.. but take 10ccs out of the pistons and you get 8.1:1... a small relief mirroring the combustion chamber would be more than adequate to lower the compression into reasonable ranges for a turbocharged engine....
My point is NOT that your comment had no validity; quite the contrary, it is a good "con" to the E31 that I failed to mention in my list. However, it is far from a deal-breaker... I have no idea how well the engine would run with stock dished pistons from an NA l28, but according to the little engine calculator I posted above the stock N42 L28 and the L28E piston dish is just shy of 11 ccs, and brings the comp ratio down to 8:1 flat. The head itself has no fundamental issues.
Besides, the "ideal quench pattern" is never achieved with a P90 and flat tops.. it is achieved with a P90 and flat tops, with a relief machined into them that mirrors the combustion chamber in the head. I would reckon that an E31, with large valves, and flat top pistons with MINIMAL clearance and a relief cut in them to match the combustion chamber and lower compression ratio to something acceptable (possibly removal of material on the head as well.. it could use SOME blending and enlarging to match the larger bore of the 2.8) would be one heck of an engine...
The reason it doesn't get done is that it has plenty of stalling points, and there are plenty of people who would use the head for a stock 240 for competition. Half of the stalling points (or more) on your cylinder head are taken care of, and are YOU going to be racing an ITS or EP 240Z in SCCA sanctioned events within the predictable future?
My point is that there aren't very many good reasons left for YOU, NOT to use your E31 for an L28ET build. Most of the good reasons are gone with the larger valves; the compression ratio is the biggest remaining sticking point (unless someone offers you $350 for the head as is..)
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the number 28 is often associated with z28's- which came with v8s.
and the number 28 has an 8 in it, and so does v8.
and so does your zee car.
Yah, See!!! his argument has you in a stranglehold....
(okay that one was reaching)
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compression ratio, i cannot say for certain because we do not know what has been done to your head.. try this link though http://www.ozdat.com/ozdatonline/enginedesign/ that should get you in the ballpark.
Oiling and cooling, I am wholly ignorant of but it should be fine?? thats an excellent question and I go out on a limb saying as much as I did right there..
As for the value, there was a time when a well prepped e31 blank no cams/valves) could fetch a bill or two, but popularity of the head is way down so I couldn't even begin to tell you. The value of the head would probably be maximum with an UNTOUCHED unit, because a piece that had never seen a machine shop is, for a racer's purpose, brand new.. it hasn't been milled on either side, and you KNOW that.
Sorry, I tapped out my knowledge hoard in my first post.. but I would love to see you take the leap and do this. It is usually agreed by "the masters" that an E31 would make for a great build, but nobody seems to do the whole L28ET with it because it isn't the well-established solution that the N and P series heads have, and it is a less common piece of hardware.
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Thankyou for makeing a better point then I did! Since I had a point in this thread and you laid it out so well,, I will take my leave.
....soo, in other words, you are thanking me for talking too much.
(I mean, I just showed up and said the same thing you did, but took four paragraphs to do so:tongue:)
Awesome, your welcome.
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holy crap you changed mine on me while i was posting a suggestion! cant complain on that one tho heh
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Keyboards' Bane! (because apparently disMembered has lost its flashy different-ness.. outside of that uber-elite capital M, mwahahahaha!!!!)
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hmm....very good points there.
i guess my argument would be that although the Y pipe is 2.5'' the two separate pipes are only 2'' i believe. maybe smaller.
i just don't know if it would flow as well as a regular 2.5 or 3'' turbo back system...
who wants to try it out?
pi * r^2 = cross sectional area.
3 inch exhaust 3.14 * 1.5^2 = 7.065 sq in
2.5 inch exhaust 3.14 * 1.25^2 = 4.906 sq in
4 inch exhaust 3.14 * 2^2 = 12.56 sq in
dual 2 inch exhaust 3.14 * 1^2 = 3.14 sq in times two pipes = ~6.25 sq inches.
dual 2.25 inch exhaust 3.14 * 1.125^2 = 3.974 sq in times two pipes = ~ 7.95 sq inches.
Dual 1.75 inch pipes are almost dead even (just a hair smaller) than a single 2.5 inch exhaust.
With twin pipe exhaust systems, though, there is a greater surface area of pipe being lowed though, so to counter that you need to slightly increase cross sectional area.. Exactly how much increase is needed depends on the length of the pipe in question.
So, in the end, a single 3" pipe is definitely higher flowing capacity than dual 2 inch pipes.. but the gain between dual 2" pipes over a single 2.5" is MUCH greater than the gain between 3" and dual 2", and dual 2.25" pipes are almost as much of a step ahead of a single 3 as the single 3 is ahead of the dual 2s.
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What was the most important variable was indexing the plugs. An indexed NGK was better then an indexed Champion and vice-versa. Moroso sells plug indexing washers.
GREAT data, and thanks for hammering home a lesson I hadn't yet learned.
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But I have found having two cars (one together and one apart) help you figure out how to put one back together : )
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Buy 3M headliner adhesive (3M only, don't get cheap here).
I was ALWAYS taught when doing brakes on a car, NEVER take the second side apart until the first side is finished. That way you can always look at the second side to see how to put the first side back together. This applies to ANYTHING on a car in pairs.
Regarding the 3M adhesive stuff.. It is NOT cheap, and its for GOOD REASON! The 3M adhhesive he speaks of is one of the greatest glues yet coneived by man, and 8-10 bucks a can is a BARGAIN PRICE FOR IT! Just don't go too crazy applying it; remember the lessons you learned in kindergarten with the white glue and construction paper versus newsprint.. wrinkles...
Heres a good oneWord, I had already contributed to this thread without even knowing it!
Clean rope can be threaded into a spark plug hole to stop a piston before TDC to allow you to either tighten or loosen a crankshaft pulley bolt or a flywheel bolt.
A piece of old timing chain can be wire-tied together after wrapping it around the camshaft sprocket to use as a wrench to hold the sprocket stationary while you torque those bolts.
Screwdriver stethoscope: stick the butt of a large screwdriver against one ear, hold the other ear shut, and touch the tip of the screwdriver to various points on the engine to loclaize a sound. Tubing can be used in the same way to fish around hunting for vacuum leaks, or to listen for flow through a fuel line or water line.
Start you car before bleeding your brakes!!! it makes a WORLD of difference having the booster aid you in your pumping.
Stock factory lugnuts for use with steel wheels have one tapered side, and one flat side. GREAT spares to throw in your toolbox; you can use them with either tapered-seat or flat-seat rims.
Standard size aquarium tubing can be used to replace the windshield washer lines.. but that doesn't take an einstein to figure out.
I have several old jack base plates from chevy OEM jacks.. they are blue, and its the type of ratcheting bar jack that lifts the frame rail from the side. I use the base plates as wheel chocks.
And here is an interesting tidbit.. If you have a selection of small flathead screwdrivers, picks, and probes, you can ALMOST ALWAYS find the retaining clip that holds a wire terminal into a large plastic plug housing. Every manufcaturer is different, but there is usually just a simple spring pin that you have to find to pry back, and you can then pull the wire in question from the large plug to inspect it, clean it, or replace it. Unfortunately, it is fiendishly difficult to find replacement terminals from any source other than another plug from the same OEM manufacturer, so it would be butt-crimp time.. BUT, in a pinch, the ability to do this can be a lifesaver! I wish I could give more explicit directions, but every plug is slightly different.. it is more of a skill than a trick, but it CAN be done.
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wow...
drag racing, v8s in Zs, solid rear axles, wheelies, all this is stuff that has no appeal to me TBH.. if anything, the opposite... im a twisties kinda guy, I love my stock datsun motor, etc etc blah blah blah.....
but still. WOW. I am seriously impressed. Mind == boggled.
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why would these so-called "twice pipes" be so significanlty different and awful sounding on a turbo motor?? They just split the exhaust up into two pipes beyond a certain point; even without the turbo in line the system comes from MSA to attach to a single pipe, the front most piece in the kit as sold is a Y pipe that splits the exhaust into two..
"Twice Pipes" proper are a fully divorced exhaust system, usually used on V engines, with one pipe per cylinder bank. "Proper twice pipes" on an L-6 would group 1, 2, and 3, and 4,5, and 6, each into one of two separate pipes all the way back through the exhaust. THIS type of setup is the one subject to the infamous power loss through loss of exhaust pulse scavenging..BUT, regarding THAT issue, it takes a specifically engineered head-pipe (read: engineered to your specific block, not engineered to some mass-produced L-esries standard) to REALLY take proper ADVANTAGE of the exhaust pulse scavenging anyhow.
My point is.. what difference is there between an exhaust system that exits the turbo downpipe, into a splitter, and then runs two pipes back to two outlets on the car; and an exhaust system that runs downpipe, through one pipe, into a muffler that has two exits??
We must keep in mind that the MSA Twice Pipes Exhaust System is "twice pipes" in name only; it is a SLIGHTLY mis-applied name, and as a result everyone thinks all these things about the system.
I'm sure it would sound different from the norm on a turbo motor; I can't quite explain away the difference it makes in the sound of an NA (even though I just posted an argument saying that from the technical side of things, it is essentially identical to a standard exhaust system) so I can understand that the sound might be something one could consider AWFUL.. is that the biggest reason that you recommend against it?
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There are a lot of inline 4's out there that are all good options... this one is a V4... most of us have seen how small a V6 looks in the S30 bay, this one would fit in a Z's breast pocket, lol.
I think the OPs intent was to imagine it fitting in a Z's SMUGGLERS COMPARTMENT, not the breast pocket
Something like THIS almost tempts me to chop the vehicle up, give it a roadster looking fascia, put a roadster windshield, top, and trunklid/rear end, and find a way to make it AWD!
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1fastZ, I am curious about the two different port grinds you posted priginally in this thread... I know you said your numbers have come a long way, but I was looking specifically at the curve of each of your ported examples.
It appears that you specifically built two port flow profiles; one more aggressive and higher flowing by the end, than the other. The curves definitively part from each other at high valve lift.
What would you say the relative characteristics of these two curves are, as it translates to the engine as a whole? I am asking a rather complex question here.. I can see the differing points, and have ideas as to how they translate to real world, but I would love to hear the answer from the horse's mouth before I start developing my ideas and wind up with some sort of misconception on my part.
Thanks!
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I think it would be a screamer personally...
The e31 head is beautiful. (BTW, could you possibly post some pretty cylinder head porn for us???
) The chamber SCREAMS "Drive Me!!" and its only significant drawback is the valve size, which as you say has already been taken care of.There are other things that pile up in the "con" factor when selecting a cylinder head that have, in this day and age, come to give the E31 a bit less of a golden reputation than it once had. For one, since they were the original "performance build" head (before the N42 cars were even rolling off the line) there are not so many heads left untouched, so they are more difficult to find. Secondly, they require the expensive valve enlargment job. Third, the later heads have other significant advantages: The "quench kings" already have a combustion chamber that is tidy and well shaped, and fairly small; and the N42 has a big combustion chamber with lots of room to weld in metal and re-shape to whatever your heart may desire. Finally, the E31 is limited to carb-only use unless you spend to have the injector notches cut.
(Incidentally, the E31 is still a VERY desirable performance cylinder head for those limited by class rules in racing to keep a stock head casting on their motor; many if not most ITS and E-production SCCA 240Zs run E31 heads.)
So, my point is, the chief reasons that people "avoid the e31 head these days" are either trivial (reasons why there is a tendency towards not bothering with them NOWadays..) or are moot (the real, hard reasons like valve work that your cylinder head already has taken care of.)
The chief concern is one that reflects into the extensive early use of the E31 as a racer head. You need to ensure that your cylinder head has not bee excessively machined. Both top and bottom curfaces of the head are areas that get milled to "true" the head, and if it has had a valve job done than it may well have served a long life as a performance cylinder head; as such, it may have seen a knife many times before. Make sure it hasn't been cut down TOO much, because there is a point where it becomes useless.
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I was only pointing this out because I (personally) did not want to see a broad brush stroke over a very fine company. Cheers:)
There is no manufacturer like Bosch.....
Two kinds of comments come out of my mind generated towards those fine people: either superlatively positive (wiper blades are awesome, they make good "hard" electrical components like alternators and starters, and I am sorta partial to their FI system since most of the world essentially just copy-catted it
) or OUTSTANDINGLY negative (spark plugs, old wiper blades, any component "rebuilt" in the third world.)It seems that while they have a fantastic business model as a manufacturer, they have been overzealous in using the name to brand sub-par products and make more money; Just a simple case of greed. At least it isn't such astronomical corporate greed as many other firms are showing us these days.
Bosch is a good good company, who earns every drop of nasty criticism they get... but you can never lose sight of their overall policy of quality and longevity. Most bosch products/components that are trouble-prone are so trouble prone that they are "knwon" factors; my friend had an early 90s volvo with a faulty EFI computer, and the whole volvo community knows about the 561 versus 951 computer issue.. they simply released a more reliable piece of hardware that superseded the failure-prone one.
I have never spoken a single word about bosch spark plugs that was NOT bad.. but I hold my tongue when german vehicles come into the conversation; The way I see Germans and Germany (being 1/4 german and a student of history) it makes PERFECT SENSE that bosch plugs could function perfectly well in german-made cars and not in any other.
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dizzy, fuel pump (as spare for someone with stock FI) entire intake power steering if it is there (for someone for spares, power steering is not something that most people bother installing as it cuts out room under the hood for engine go parts
) The seats ought to bolt up to your 260, but I may be brain-farting on that one.
Personally, I cant get the idea of a complete rear subframe swap out of my mind.. I would want to go with something like a 280ZX, 240SX or 300ZX with rear disc brakes. If I were anywhere close to you I would be interested in getting the rear subframe, MINUS the R200, because my 75 280 came with one of those
Unfortunately theres one of those continent thingies in between us.. bugger.
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John, thanks for clearing me up on that; I had heard words bandied around but never managed to catch the complete definition between the lines.
Daniel: Understood, I realize that most of the front end sealing work is an aerodynamic concern over a cooling one, but I was primarily concerned with establishing that YOU had, on your car, ensured that the radiator was the only path of escape for that air. If you have sealed your front end up, then the comment was moot; I just wanted to make sure you weren't losing any potential cooling airflow anywhere. (The comments regarding dumping the air were made because you expressed a desire to AVOID blocking the front off, and the racecar package is not one that can be looked at one subsystem at a time; when considering cooling, you have to think about airflow, which means you have to make aerodynamic design a part of the cooling system development process.)
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Also, buy a real racing oil cooler like a Setrab or a Mocal.
John,
I highly value your opinion as a top-notch racer who cuts no corners; therefore, I am very curious as to what you would consider so much better about a "real racing oil cooler" and what difference might exist between, say, the Earl's unit he installed and the 2nd gen RX7 oil cooler of junkyard fame? Is this an airflow thing? I was unaware of any oil cooler disparity, please enlighten me:coollook:
Or was that just said that way because he had mentioned the idea of using the trans cooler coil in the aluminum radiator as an "oil cooler?"
Regarding the aero ducting and air flow through the radiator.. the key fact to cover is that all the air flowing INTO the front opening flows both...
..through the radiator, and
..out from under the hood.
Reducing frontal face area is one method of reducing total air flow into the engine bay, which helps with the stalling, but another key point is that much of the air hits the front opening, and then rolls down below the radiator cross member and thence under the car. The MOST IMPORTANT PART of the radiator air ductwork is the effective transmission of all air entering the "mouth" through the radiator coil.
Air can be eliminated from the engine bay by ventilating it behind the wheels, underneath the fenders without even adding actual grills in the sheetmetal fender.. just discharge the air to the space underneath the fender, and it will flow out. Trust me, I know, I seen it on the internet somewhere
(No, seriously, I DID see someone here successfully venting this excess air through hidden holes underneath his fenders.. they were essentially under the hydraulics and battery tray. I just can't for the life of me remember who, or even in what thread.) -
BLUE, thank you, and what wonderful timing. I was looking at a flat top set of carbs with manifold earlier this afternoon, and should be back at the shop within the next week... I THINK it was an N-33 but it may have been a 36, and theres the nonzero chance i'm mixing the numbers up entirely but it was a flat top manifold.. the carbs were still on it. Anyhow, there was that and others handy; the race car engine is being rebuilt so its nice pretty manifold is off, I should be able to get some good shots.
If I make it up there I will review this thread first, get the measurements requested, and get anything beyond what we already have here that I have handy.
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on my 87 subaru EA82 (1.8OHC, hitachi built EFI) the ECU has a green LED that comes on whenever the O2 sensor reads "rich" and cuts off at stoich or lean.
Does the Z have the same thing???
Yeah, the ECU's do have this same thing. I forget if it operates as you said, .....so as i was driving last night i noticed that the blinking light isnt just blinking all the time, my observations concluded that (unlike in the 1st post) at a dead stop the light flickers sporadicly, in neutral when the car is moving the light turns off, in gear at steady rpm and on the throttle the light blinks consistantly, and if i barely have my foot on the gas the light will stay solid. i am still doing reaserch from other sites and i am gonna call the nissan dealership and ask some questions, i lost my owners repair manuel so i cant check and see if the answer is in there.Yep. I bet it stays on constant anytime you have your foot on the pedal whatsoever.. on passive cruise it would go back and forth across the stoich threshold, and at idle you are doing the same thing, and neutral cruise still spins the clutch a tiny bit so the engine is being imparted a bit of energy from the slowing car, so it would naturally go lean.
Remember, this is just a narrowband O2 sensor.. it is slow reaction time (about a second or more) and it is not very good at what it does; it pretty much tells the computer "RICH" or "LEAN" in a simian manner. They fucntion through a range of 1 volt, and ~.5 volts is stoich, lower is rich, higher is lean. It works about as well as your ear, but it outputs a signal that electronic processors can comprehend.
Thats cool to know, I wonder if the earlier model ECUs have this.
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In June 2007' issue of Super Street, page 64-65, shows a nicely modified bmw z3 utilizing a Stack super sports cluster by Defi. It has a sweeping boost and tach, while a digital section resides underneath. Perhaps enough compromise between digi and mechanical ? Here's my vote for just installing a Porsche 996 turbo gauge cluster, incredible design imho.
Incredible design.. but only a 7500 RPM tach????
It IS beautiful, and incredibly functional.. AND it would free up the three holes on the center of the dash to house three other gauges (boost, oil temp, and A/F?)
I just dream dreams of 8200 revolutions per minute, is all....
ZXR .. Super turbo prosponed BMW V8 planned
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