Tony D
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Posts posted by Tony D
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What is the specific issue? I know when I was 'Chevheaded' I had to grind out bolt holes and stuff to get them to fit. Especially if some shop had milled the heads and not matched the manifold mating surfaces...doublegaskets anyone?
And how much of a loss is 'sell it at a loss'? Being I have crates of old 40PHH's sitting in the back just itching to be resurrected as ITB's, this manifold would give me a good excuse to do something with a SBC in that S130 sitting out back...
Inglese Manifold with 44IDF's or 48IDA's is nice, but the price isn't so...er...'Attractive'...for a little sweat equity or perhaps some angle milling on the flanges, no sweat off my brow.
Specifics?
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Most common method for cutting the laminated safety glass is to mask the window save for the 'cut line' with sheetmetal and heavy tape, then use a sandblaster to 'errode' it out with multiple passes. Masking both sides you alternate side to side and work to the plastic in the middle which should give way fairly easily.
If you have a good, precise nozzle, cutting will be fairly straightforward, with a slight hump in the middle, you then 'stone down' the end with a water flooded whetstone.
If you alter the sideglass so the upper profile remains unchanged, you can simply cut the bottom of the glass, and once your're through your done, as it's all hidden. Just reattach it to the guide and go from there.
For side glass, though, it's almost as easy to make your own polycarbonate windows and be done with it.
Windshields use the same procedure, but you won't have to finish it as it's all inside the rubber moulding anyway.
The finishing only comes if the part you cut will be on a roll-down portion, and like I said, though the templating is more complex, if you can do your chop without altering the door glass profile up top do that cutting where it won't be seen and your done without any finishing.
BTW, if you can get a pnuematic belt sander set up with some black emery strips you can do that finishing pretty quickly. Why pneumatic? Because your flooding it with water while polishing!
Hope that made it clearer.
Good Luck!
with the sandblaster and mask you 'can' cut it off all at once. You don't have to nibble away from the edge. For a 4" chop that would take forever! Even with agressive media!
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After re-reading Tony's post above, another thing that occurs to me is that if you have deadheaded the flow with the Thermostat shut, the only way for it to see the water temp "signal" is for it to wait for the heat in the head to creep out to the t-stat housing via convection. Seems like the temperature of the water in the head could get pretty high before the water in the t-stat housing gets hot enough to open the thermostat.
And this is why I ALWAYS advocate using the external bypass line from the lower thermostat housing back to the lower radiator hose inlet fitting, and not relying on only the internal bypass in the head/block to recirculate the coolant---the thermostat housing is a deadspot if it's not vented.
There are people who argue that 'they have done it for years with no problems' but when you realize why it's there, you start having serious reservations about removing it for any reason.
Tim hit it straight on the head!
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Very good point, I should have said "Class" he is correct on the terminology for sure!
The points on type of fastener and corrosion are also well taken.
I remember both the Bowman and Lawson Hardware Reps trying to sell me on their 'Ultra-Grade' Hardware which was 'better than Grade 8'---and they always trotted out tensile strength. Which is fine if you need that. It can also mean they are brittle, as rejr alludes to in his post. As you can see the "No Marking" can have a drastically lower strength rating. And that is why I was cautioning about misinterpretation of the bolt head marking---being a manufacturer's mark, as if it was 'Class 8.9' it would not simply say '8', it would be '8.9'.
Beware.
Aluminum fasteners. Love that timesert example! I have a story about aluminum fasteners, and how someone thought they were 'too heavy', but that's for another time...LOL
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Please, when your clutch burns up, don't coast in the racing line. Especially after a blind rise on the track, after dark, with dim tail lights.
"Stay out of everyone's way" is my general rule. At least I try to. A track day is NOT a race, it's a learning experience. Use it as such and you will be far better off. There is plenty of time to be competitive later. Concentrate on the lines and technique. Ifyoustart trying to compete, you loose everything you've gained in the classroom session.
Have fun!
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I guess 'far' is all in the perspective. Four hours drive is not 'far' by my reckoning. Then again, I joined the service and that makes you grow up pretty fast. Basic Training was 1800 miles from 'home', Technical Training was 600 miles from 'home', and First Duty Station was almost 7000 miles from home.
If you are an independent person and can function on your own, move. If you're still living at home and haven't really been out on your own then this may be a bigger step than you are ready for at this point in your life. Eventually you will find the stones to move away and be your own man,it usually happens.
I missed my 25th High School Reunion, but got the skinny from those who went, there are still the same guys hanging around downtown that did so when they were in highschool. Nothing wrong with that if you can make a living that satisfies what you want out of life. If you can't, then you have to make some adult decisions that may seem daunting, but if you never confront them, you will never grow.
You don't grow staying comfortable, you grow doing things that make you uncomfortable. New job, new things to learn, new location. Like the saying goes 'the green water never leaves the pond, it just sits there, and nothing lives in it'...
Good Luck.
BTW, I work in Vegas all the time, and I could almost say 'There's Gambling there?' If I didn't do work AT the Wynn Casino, I wouldn't know it...save maybe for the slots in the gas station. It's something that you don't need to expose yourself to, and there are plenty of places where it's not prevalent. It's not Gomorrah...
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I guess I will never be posting photos of my 69 Corvair Fuel Economy Rally Car from the 70's here then....
That 'ecomodder' site will prove to consume more of my time than is healthy methinks...I will be spending some serious time there now that I see it.
Who cares what it looks like, it works.
Was that a Megaview Megasquirt Controller on the dashboard????
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There was an 'IMSA' kit in the old competition parts catalog, with the typical 99996/ Nissan Part Number for externally produced parts the Competition Department was reselling. If you can find those in the FAST program, they may show up. I thought I had a scan of that page of the catalog, but I can't find it right now. Damn, I got to sort my files!
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Nice "Patina".
00305 is in much beter condition chassiswise.
Only six different off the line, but such a difference in overall condition.
I guess the Northeast is harder on a car than SoCal...
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KTM is correct, which is why I'm pointing out that '8' on the bolt head means nothing, and may well mean SUBGRADE fasteners.
Was it John Coffee that used the 'batch built in china crap' to desribe the bolts? Pretty apt.
if it doesn't say '8.8' then it's not grade 8.8 and it's a dangerous assumption to think so!
The only headbolts I would consider would be as KTM points out, 10.9 or 12.9.
8.8 is at least a GRADE of fastener. When you deal with a lot of hardware like I do, you realize ANY GRADE of fastener is better than an UNGRADED fastener. Which it sounds like the local ACE is stocking, and ungraded fastener, which likely is SUB GRADE 5 in American Parlance (Grade 3 Hardware or worse)....
I am very leery of using hardware that do not meet some objective grading criterion.
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I'm no good with drawing diagrams online....
But if the engine to chassis ground exists, it ONLY allows a loop if it's also concurrently linked to the negative post of the battery. That is what I mean, you loose voltage sensing if you disconnect the negative cable, and you simultaneously loose the return path for the field excitation, collapsing the field in the alternator killing everything. All my grounds which normally would come from the battery negative post (To Chassis @ Firewall, Starter Bolt) are all on one side of the switch, and the other side goes to the negative post. If 'chassis' is not connected to the negative post on the battery, there is no 'loop' that is completed, and the electrons can't flow.
On the Lemons Car, the "Star Ground Point" on the switch went to the dash ground bar, the head, the intake manifold, the block, the starter mounting bolt, and the chassis ground point on the firewall.
Many of my sensors are of the two-wire type (GM) and therefore go back to a common ground bar that is grounded at the same place as the ECU (the dash ground bar)---from experience keeping the grounds on one point when possible keeps sensor error at a minimum. Especially with a Megasquirt. Some sensors for the dash gauges are grounded through the engine head/block, but they are brought back to the same 'star point' on the disconnect switch to the battery negative.
The other side of the switch went to the negative post on the battery.
"Electricians" wouldn't like how fuel injector circuitry works: every control scenario I know of switches ground on them...
I was under the impression this was some sort of 'Emergency Stop' scenario Disconnect and not a routine shutdown circuit. Emergency Shutdown is a particular situation, you shouldn't be killing the car switching off your 'positive disconnect' either. I think that is a moot point.
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One big reason is that 40mm Solex/Mikuinis were STOCK OEM PARTS on so many cars there they are CHEAP. A used set of 40mm's was rarely more than $10,000 yen. Why try to charge more when any mook could go to the wreecking yard and yoink the 40's off any number of Toyota 2TG or 18RG engines for Carbs? Sure, used 44PHHs were slightly more, maybe 45K yen as opposed to the ubiquitous 40's. But to not run 40's when they were that cheap (and EVERYONE new how to tune them) why not?
As for ITB's....I have a nice set of Vintage HKS units from the early-mid 80's. The Japanese have had Analog Fuel Injection Triple ITB's for over 20 years...almost 30 now. Triples are there because they're cheap.
ITB's are out there, but due to costs they are less visible. Many people think the "Wangan Midnight" S30 has blowthrough carbs, but only at the beginning, by the end of the filming SSS had swapped over to Triple ITB's, and most people didn't know the difference because visually they are very similar.
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I'm in the "Negative Terminal" camp as well, I just posted above to BJ Hines request about similar issue. I don't see why the sanctioning bodies insist on a positive disconnect, without a ground circuit nothing will function. If the positive battery cable starts grounding to chassis and arc welding, it only does it because you have a negative cable going to the chassis, removing the ground path will stop it as positively as cutting off positive power. And doing it on the negative post kills alternators if you run your chassis ground through the same switch. The alternator still requires a complete positive-to-negative path to make power. If you pull the positive cable, the alternator will still run the engine. You pull the chassis ground/negative post off, and it kills it.
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It cost us $15.99 for a master disconnect switch...same one everybody else used. Ran ALL grounds to the switch, and then to the negative post of the battery. If there is no ground, postive has no place to supply electrons to the backside of the battery.
A $2 6A Capacity Diode (rectifier) on the "L" terminal on the alternator (if I recall correctly, it's the one that comes from the ignition hot, not the sensing line.) to prevent reverse-feeding the circuits in the car so the dedicated ignition cutoffswitch didn't keep the car running after it was switched off.
All power fed in to the car's electrical circuits went through a master cutoff 'push to open' 75 Amp switch closest to the driver that cost $7.99. If you pushed it, it killed the car, period. If you opened the key switch on the negative terminal of the battery you killed the car, period.
I have heard you 'need' to have those dual-circuit disconnects to work with alternators, but nobody can tell me what kind of 'damage' will occur using the ground-depriving scenario I employed. Even an alternator can not make power if it's not grounded. Even if you think 'island mode' if the battery is disonnected at the negative terminal, and all your grounds go there (even if through the chassis, as long as the chassis grounds all are isolated from the battery ground terminal) it will not keep excitation as the field circuit opens.
On the Lemons Car, 'cheap' was a prime consideration, and it wasn't until after I built the damn panel did I find out they did not require an external power kill switch (like everybody else on the face of the planet who sanctions races does!) Oh well, it was a learning experience.
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as for using ACE hardware bolts, forget the grading scale. ALL internally wrenching fasteners are grade 5 minumum, if they are of any account. Grade 8 internally wrenching fasteners are *MOST LIKELY* going to be fine for a mild L-series. ARP headstuds are not required for a good engine, but like others here have said, if you're going to be working on it a lot, go for it. You'll like the extra insurance. In OTM's situation, the ACE hardware store bolts will probably be fine, as long as he keeps an eye on them.
Those are some very dangerous assumptions to be making for such a critical component.
If the head of the bolts only had an '8' on the head, then by the industry standard, it would be a manufacturer's identification and nothing more! When they say it should say '8.9' that is what it will say. The markings for bolts are very specific! Lacking of a specific rating marking denotes the minimum quality standard for the class of fastener.
For the costs involved, I would not be 'cheaping out' on head bolts, studs, connecting rod bolts, main cap hardware, etc...
Japanese manufactured automobiles, just in the way they interacted within the supplier network and the integrated governmental oversight they had usually had supplier relationships that allowed them to have much higher standards for hardware in many applications than would normally be supplied to general industry. Head bolts/studs would be a prime location for this kind of 'cooperative relationship' where the supplier gave them a beyond industry standard bolt or stud, thereby cementing a supplier relationship longterm, and insuring there would only be ONE source for the bolts. Everyone made the maximum profit.
American engines at the same time were really a 'low bidder' application, where each engineering decision was MBA'd and Accounting Department/Purchasing Department lowballed. Consequently they engineered to industry standard fasteners to keep construction costs as low as possible.
There's advantages in each way to engineer the package, but on German and Japanese vehicles, I would be VERY wary of exchanging ANY engine hardware in critical locations for run-of-the-mill industry standard hardware. On a SBC...sure, I can see lots of stuff that has Gr5 in it and a possible cheap upgrade to a Gr8 fastener would work fine.
But on the 'ungraded' application specific hardware like a Nissan Head Bolt...
Not for me! Stick with OEM or BETTER quality.
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SU's are another bag of tricks altogether. I have heard of British Applications where they were used blow-through, but have never seen one firsthand.
All my experience with SU's has been drawthrough application on the Corvair. I would just run them N/A and save your money. I wouldn't want to tackle SU Blowthrough, at least on early carbs (pre 73) because I really don't know what the limits of the fuel feed tube are, and how the jet sealing area works under the various pressures. It is all 'sealable' through the use of clean air piping and drilling holes, etc...but that's a lot of work to go through when other alternatives are far more practical.
And the boost threshold point has nothing to do with tip-in pops, it's the combination of plenum sizing, engine draw, and compressor flow that causes the transitional popping issues. If you lag the compressor so much that the carburettors are on the 'main' circuit when boost comes on, then it won't be an issue. Though you limit your useable rpm range. The solexes run on the idle jets till almost 3000rpms, that is how they get such great fuel economy. On an SU, the fuel metering is totally different and much more complex in regards to spring weight versus vacuum exposed to suction piston weight compared to needle station height when coming on boost. Egads, my head is starting to hurt to see how that interaction would be attacked!
The 'problems' are not related to turbocharging, it's related to 'blow through turbocharging of solex style carburettors', it's not an issue with an EFI turbocharged application. Which was a point made early on in this discussion.
If you suck through a carb on a supercharger, you will have the same success as if you suck through a turbo.
And the reason I say 'early' SU's as an issue is they don't have an integral float bowl like the later carbs do. So that fuel transfer line just looks like a problem area, one crack or break when you are under boost and you are gushing fuel directly onto the exhausts. Not something I would look forward to during 'testing to failure' in the real world. Of course, dealing with a power valve under boost on the later carbs would present it's own issues, but it would seem like they are much easier to attack in a blowthrough application.
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I've only talked to a few guys running turbo'd carbs, but they were all like SBC's with a single 4bbl and they were saying its a pain to tune at times for boost. But i guess with the plenum design on a triple setup helps to cure that?
The difference is most guys with 4bbls that are blowing through them is that they make a 'pressure box' that equally pressurizes both the venturis and the float bowls. Many times it encloses the entire carburettor!
The design of the Mikuini (and the other horizontal carbs like Weber, dellorto, etc) is such that the float bowl can easily be pressurized separately. Some use a divided plenum, or like SHO showed, you can put a separate line, plug the normal breather port for the float bowl, and pressurize it from something added under the jet cover, or direct tapping to the float chamber. (Some Weber Guys will make a round 'standoff' for the jet cover, and put the boost in there, instead of through the front opening...that opening on the front is covered by their plenum, which only has the throttle bore openings in it.)
Most of the 4BBLs have simple tubes and they usually are right in the center of the throats, making it difficult to segregate. Sure, you can tap and plug them and then drill the bodies, but most guys just 'buy the big box' and go from there.
This is the same approach Cartech took when they designed their plenum---it pressurizes both chambers equally, so as a result you need MUCH larger jets in the main side than you would running any of the Japanese Boxes. We had a clubmember at GroupZ who had the full Cartech Setup and his jet sizes were MUCH larger than mine were. He also got fuel mileage that was in the very low teens. Granted he had a 3.0 and mine was only a 2.8, but the performance was equivalent when dynoed. Somewhere I have a video of him saying his jetting setup... I could find that, and then compare what was in my Solexes, as we both had 44's.
One of the things that impressed him about driving my car was the lack of the transitional popping. Same for another clubmember that had a 2X4 plenum, and was making somewhere north of 300HP on his 3.0 as well. No matter how they jetted it, they could not get rid of some transitional popping. I didn't know what they were talking about until I changed to the smaller 2X4 plenum without segregated float bowl pressurization.
Really, it's a twofold issue. Transitional drivability problems---which I link to the generic 'plenum style' not enriching the main circuit enough on-boost for transitional stability, and the Instant Boosting you get on the smaller plenum. What I found myself doing was driving with a much heavier foot simply to get the car from vacuum to +3psi boost so I didn't get t he popping. It was the worst from 0 to 1psi. My fuel mileage dropped (even with carbs) roughly 2mpg with the smaller plenum due to this driving technique.
What I'm getting at is it doesn't have to be that way, it can be a nice smooth drive where you aren't going to 25 and 30% throttle just to pass someone on the highway under normal speed conditions. And that kind of drivability really rewards you with fuel savings in a daily driver.
Regardless, the 17mpg I was getting was 'acceptable' but when that dropped to 15 or lower on the same jetting it's when I started considering EFI. I can live with an occasional pop or sniffle from the carbs, such is the beast. But I had a 'driving circuit' south of my place in Corona that had a slight grade on it, and if I took it at highway speeds it would sneeze and cough the whole way. A larger jet would have solved it, but I didn't need them with the segregated plenums I had run, and that is what got me looking at 'why' instead of just throwing more fuel at it and saying 'it works good enough'...
4BBLs in a plenum (the big box that surrounds the whole carb, not just a 'top hat' style pressure apparatus) will be a PITA to get at anyway, just because you have to disassemble the box to get to the jets! And if it's not a mechanical secondary, then tuning the diaphragm and spring combination to open those secondaries would be something I would not choose to tackle. I don't even know if running non-mechanicals in a blowthrough ap would work. Most of my time with 4BBLs was in draw-through where they seemed as easy to tune as anything else running a 4BBL.
All that being said, there is another way to do it, and that is called "Modulator Rings"---basically you make a plate to fit over the main throttle bore that has a hole roughly the size of your main choke (say you are running 44PHH Mikuinis with a 32mm Choke--you make an 'orifice plate' of 32mm). This does the same thing, and could be done on a Cartech or other 'box style' plenum. Under normal aspiration, the orifice doesn't come into play, but during boost when air is being pushed through at a higher velocity the modulator ring (orifice plate) will act as a pre-venturi and make the main circuit tip-in much earlier through the same effect as the segregated plenum. This is how you did VW's. And with their pressure boxes it was easy enough to pop em off, and make the hole slightly larger to trim/tune the on-boost enrichment characteristics. The general rule of thumb is to start at main choke size and work up from there until you get the enrichment characteristics you want. I won't say it's an easy task... it's kind of a PITA if you ask me, but if you are running blowthrough carbs it will work to enrich you under boost without having to change to humongo jets that just make the car sloppy above 3000rpms without being under boost.
I hope this is making sense? There are a couple of ways to do it, IMO the easiest way is to either externally vent the float bowls like SHO diagrammed, or use one of the pre-designed boxes. Screwing with Modulator Rings was just something I wasn't willing to do on another vehicle at that point in time. Even with an external vent, you may well end up orificing the entrance of the plenum for more pressure differential. Sure...it's a restriction, but making ONE orifice is a heck of a lot easier than precisely trimming six modulator ring orifices to put back in between the plenum and the carbs!
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Why's that?You go onto boost mapping with the slightest touch of the pedal due to insufficient plenum volume. The Centrifugal compressor will overfeed the reciprocating compressor (engine) really quickly. It's why they put such large receivers on screw and centrifugal compressors (suction bottles is another name for them) when feeding a reciprocating booster compressor.
As a result of the instant boosting in the manifold, you end up running in a 12:1 mapping, instead of something more conservative. Your mileage goes to hell... Now, if you put a much larger turbine section on, so it's slightly laggier you may restore the balance of NA cruising, but it kind of defeats the idea of having a turbine optimized for response. With a larger plenum, small throttle excursions will not result in the increased flow causing a bump to say 3psi instead of '0'.... In a megasquirt the difference in sized can be seen as a jump almost instantly from a 54kpa cruise to 108 or 110kpa instead of from 54 to 80kpa with the larger plenum. The only thing changed in the test was the plenum.
Also I note the BOV tuning has to be retweaked due to the plenum change. The blowoff action is much harsher on the smaller plenum from what I can hear.
Exasperation is more like it. I don't know how much clearer those statements can be!
I'm not asking my words be taken as gospel, but I do ask that those who ask the questions give me the common courtesy to actually read the replies I have given to their previous questions.
Your question about the MAP reading being inaccurate is so far afield, I don't know where it's coming from, I can not draw a logical link between the highlighted sections above---which are in direct response to 'why's that'---to me saying the MAP readings are innacurate.
The reason the mileage goes to hell is precisely because the MAP is accurate. I thought that was clearly and adequately addressed in the above passages (the first two sentences of each paragraph specifically).
I'm not getting defensive, I'm getting exaasperated as I am at a loss to figure out how to convey what I'm saying as from my point of view it looks fairly clear if it was read.
What I was getting at as a side point was that if you have specific questions relating to MAP based plenums then I'd recommend addressing them in another thread and not muddying up the water in the Carburetted Thread. Pointing out the differences of what works why in the two different systems is one thing, but starting to explain why each operates the way they do in the same thread will invariably lead to someone confusing statements about MAP based EFI Setups and Carburetted Setups.
Again, I don't know how much clearer I can be on the subject and why I said what I did. If you want clarifications on the statements (if required), I'd follow on in another thread, as I would hope this one could stay on the Carburetted setups, and not get muddied by talk on MAP.
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You could talk to Jeffp about his, I think it might be available soon if not already.
He set up the CAS yesterday, and is bugging me about availibility to go to the dyno in the coming month...
But my wife's car would work nice with his box as well...
Oh, and on the 3" DP and Exhaust, regardless of what size the outlet of the turbine is stock, JeffP showed 20HP from the addition of the 3" exhaust and DP on his otherwise stock T3 (long ago, but documented on his webpage).
I can't believe you are running 12.004 and don't already have a 3" system on there!
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Can you hit 600hp with a ported out stocker? I'm sure it's possible, but its a good step along the way, and will make your setup more effecient.
That really depends on what 'Stocker' you are using! JeffP about dumped in his drawers after measuring the I.D. of the Euro Turbo Manifold compared to his ported US Spec Stocker, and his SFP Tubular Header.
The 1 5/8" I.D. of the SFP Tubular Unit is actually smaller than the Stock European Stock Unit! And given the photos above of what appear to be the 'modified' SFP unit with 'expansion joints' installed in almost the same places as the Euro Turbo Manifold has!
Short of MONZTER's efforts which look a bit like Electramotive's efforts for all-out HP, a stocker will haul you a long way. And a Euro Stocker (if you can find one) will go even further. Getting 500HP on an internally-wastegated stock-looking turbo does have some advantages, depending on where you are living in the country...
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Yeah, ITT-Canon Style Plugs...
Of course that site is recomending Raychem wiring, though not specifying if it's Tefzel coated, or what...
A/N is a standard, but there are other more secure tubing standards out there, depending on how severe the service. A/N is popular as they are light, easily available, and at one time were very cheap and available as surplus. That's how "Earls" got it's start!
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3/4NPT is almost an INCH is diameter, nowhere near 9/16"!
Tapping for 1/4NPT is about right at 7/16" +/-
You can't find a pipe plug to screw in there and check? Home Depot sells them, and if you bring the fuel rail into the store (or any decent hardware store) you can try fittings until you find one that fits...
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Fine, the map sensor reading taken WITH a smaller plenum. I think you knew what I meant.
Improved throttle response makes it harder to drive conservatively, certainly. But I think that's why most of us went with ITB's in the first place. I think I'll hold off chucking my cartech plenum in the bin.
Forrest, I don't know if you are intending to be a smarta-- throwing in little comments like this or not, but I really have no idea what you are talking about!
THE MAP SENSOR IS IN THE MANIFOLD BELOW THE THROTTLE PLATES AND WILL NOT BE AFFECTED BY PLENUM SIZE, incipient boost conditions below the throttle will be difficult to judge. If you have ITB's and are sensing MAP in the plenum above the throttles, I don't know how I can help you. Best I can say is that the comments in this thread are SUPPOSED to be directed towards CARBURETTED applications.
You seem to have a real problem with my statements. I guess that will have to be your problem from this point. You're muddying the post asking about MAP in a Carburetted Thread. I've tried to expalin exactly what I've been referring to, and you seem to not be getting it---I don't know how to make it clearer. If you live at WOT, then so be it. You are picking flypoop out of pepper with boxing gloves and lumping the 2X4 plenum voulme problems with your personal choice of the Cartech plenum (in a NON-CARBURETTED APPLICATION). Though similar in the sense that it's terrible as a CARBURETTED PLENUM compared to the HKS or SK, it may well have suitable volume as an EFI plenum.
You seemed to take offense that I said the Cartech Plenum was trash FOR A CARBURETTED SYSTEM, even though you are using it in an EFI setup and are having some sort of luck doing so. Frankly what you do with your Cartech Plenum is up to you. Keep it, but before you start making smarta-- commentary quoting me about 'chucking it in the bin' try it with carburettors and a turbo that will spool at 3400rpms and see if you like what it does...
I don't really know what the problem here is, but partial throttle drivability and tractability while in transit at 60mph IS a concern. A 2X4 Plenum will not have sufficient volume to prevent any sort of...you know what? It's your problem, not mine. Figure it out. I don't know what more I can say other than what has already been said.
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If you have properly jetted the engine for N/A operation, with an HKS plenum up to around 5-10psi you will be amazed to find no (or very little) jetting is required to be changed. The temperature could come into play with higher boosts un-intercooled, but if you run a cooler, then it's not an issue.
That is what I was getting at for the longest time: The pressuirzation of the float bowl, even by a fraction of an inch of water will allow MUCH more fuel in to the circuit under boost situations (same as if you changed the float bowl level the same ammount on an N/A)
I'd say run it and go from there, there's no 'baseline' without knowing where the engine was as an N/A. I've pulled my plenum off, pulled the turbo and then reinstalled headers and run the car the next morning as an N/A vehicle! Did it at the last MSA I took my 73 to---Sammy trashed my turbo bearings and the next morning before the car show I pulled out the turbo and drove it into the show 80 miles R/T no problem.
Early 70s Japanese race car aero
in Windtunnel Test Results and Analysis
Posted
More likely the FRP hood is flexing due to built up pressure at-speed. I have documented this on the Paul Neuman G-Nose. Took photos coming out of the last turn before the pit straight at Watkins Glen, and the hood was down securely (at 80mph perhaps). By the grandstands, at a speed over 100mph, the hood was bowed up noticably.
Pressure gotta go somewhere, bowing a flimsy FRP hood is the easiest route out!
They could have set the hood pins 'loose' to let it exhaust at the back as well. But you would have to see the cars sitting still to see how they set up the pins. Many times the FRP pieces have a slight bow to them and spring up when fixed hard at the front end. Even my steel hood does that!