Tony D

Found this as a 'read and comment' in my work inbox. The parts involving basic surge concepts is pretty good in explaining it. Since I don't really work with variable speed stuff (gas turbines) any longer, thought this take was interesting: http://www.documentation.emersonprocess.com/groups/public/documents/articles_articlesreprints/d350790x012.pdf The graph I normally work with, and that I mentioned above is roughly approximated in this document on Page 1 http://www.osti.gov/bridge/servlets/purl/823041-YQ0uNi/native/823041.pdf I don't expect many to read it...it's not your job. But the graph is there and you can see the axis' I was referring to and the surge line, etc... Man, I read this stuff. I'm pathetic... I should be doing something else than reading technical papers on a nice day (er...evening) like this! I feel like Gilbert...

Boost Threshold Point is the rpm under load whereby the engine turbocharger combination is capable of making full boost. I'm figuring you make 2-3 psi at WOT at 1500-2000rpms, and as you pull under load, like clockwork at 3400rpms the boost gauge shoots to 17 or 25psi. Meaning your boost threshold is 3400 rpms. If you put a .82 housing on there, the point where you make that transition from 2-3 psi to full boost will likely be higher---say around 4000rpms instead. Stonewall is the point where the turbocompressor is flowing as much air as it can, and can't flow any more. Usually this is at a point below maximum pressure or design pressure. The hot side A/R will not affect this at all. The compressor sizing and operational speed, as well as the flow map will determine where flow stonewalls. Stonewall can stress the blades, but you won't hear anything. JeffP gets to 25psi or thereabouts and the horsepower graph just flattens out. It's a very distinctive curve on the dyno when you are out of air, as opposed to surging, or AFR issues. This doesn't taper off, it just flat plateaus (er...around the same HP that Garett says is maximum for the frame capabilities). You aren't hitting Stonewall at 20psi, you are hitting the SURGE LINE due to MINIMUM flow. Stonewall deals with MAXIMUM flow. Surge deals with MINIMUM flow. jeff's GT makes more pressure than 25psi, but won't make appreciably more power. On a stock head he would likely run higher boosts than the worked head. Moves where the compressor is operating at all around the pressure/flow map. By upping the boost at that point (once stonewalled) you run closer to surge (natural surge) than stonewall, and that is bad. You can run in stonewall, you will just not make any more power. If you up the pressure from stonewall, not only do you not make more power, you run the chance of natural surging the compressor at some point and it's stressful on the blades. in industrial compressors that are known to have to run in stonewall before being ordered, usually the compressor wheels will get extra treatments like shotpeening and stress relief so they can stand the continual stress of flowing everything it can at any given pressure. I digress... All the .86 housing will do is up the point where you make full boost, and maybe breathe better out the back end of the car---if you haven't taken exhaust backpressure readings you don't know if you need it or not. Likely not. My life is revolving around surge at this point, see what you can take away from this article someone sent me a couple of weeks ago... I got to read so much of this crap it gets numbing and I wonder if I'm relating it even halfway cogently sometimes without getting to geekspeakish... http://www.documentation.emersonprocess.com/groups/public/documents/articles_articlesreprints/d350790x012.pdf I thought the part about 'basic surge concepts' was pretty good. I think I will link this in the other post as wel...

No, it is not a matter of 'timing it all'... If your piston to valve clearance is insufficient they come in contact. There is nothing you can do but add clearance: Loose lift or cut notches in the piston. Define 'bigger cam'... What kind of lift are you talking? 0.575"? 0.620" at the valve? If not, and you are talking 1/2" lift or less...chances are good notching will not be necessary, especially with stock valves. The only way to know is to assemble the works and clay it up. Then work the pistons for clearance. Notched pistons would add more clearance at a slight penalty of compression ratio (less than .1, .2 CR point...) Only run the notches if you NEED to, but you were sounding like you wanted an 'assemble it with the least chance to screw it up' methodology and that would employ the notches. They don't affect CR that much. Anybody using a flat top in an L24 is not building a 'high compression' engine by any means. (Or even a stroked L24 like mine was, using positive deck height!) BIG cams like compression, you will not be making it with flat tops on an L24. It will not like a "BIG" cam...so again, define 'big'... I'm thinking your cam will be 460 lift, and far less duration than you think you need because of the low compression you will have using stock components. Now, running an 05L head, or even the early E31 head and the stroker L26 will boost the compression far more than any E88 flat top... You don't have 'dished' pistons, they are for all intents and purposes identical in terms of compression ratio with the head you use. This is all a stock buildup. Well under 10:1 compression no matter how you slice it, not high compression by any means---meaning again 'no big cams need apply'...

They laughed when we put the wing on the Corvair before the Perchville 4X4 rally too... Then when a 19 year old kid beat the field by over three laps in the final heats they did what all sanctioning bodies do to people who run fast using wings: They Banned Us (or at least our configuration) Meh... 1.22's are FAST there! I don't care what you're driving/riding. Can't argue with the results.

Yes, it sounds like the flow point through the stock components is causing a minimum flow surge situation. JeffP has a GT35R with a .63 and the turbo is out of air before 25psi with his ported head. Going to a larger A/R on the turbine will only increase boost threshold point. By 'out of air' I mean you can see the HP level off and it's obvious the engine is nowhere near it's power potential...but the turbo won't make any more power or pressure no matter what you do. STONEWALL is what the compressor terminology is for that flow point. It IS possible to surge the compressor at lower pressures than you would think, this is a minimum flow surge you are experiencing. Unfortunately it's the same sound as a natural surge (maximum flow, maximum pressure). In essence they are the same thing...for the pressure you are at, there is not enough flow for stable compressor operation. Have you tried manually lifting the BOV open slightly while under boost near the surge point to see if it supplies more air and doesn't surge? When a compressor surges you have to either lower the pressure, or give it more ability to flow...usually this occurs simultaneously. BTW, the power and HP at 9psi is roughly very close to JeffP's testing. He was making 380Tq at 4500rpms, at 8.39psi of boost. It's more now, with higher pressures... GT35R. Jeff had some BOV or low wastegate spring related issues with his setup as well, you might get some info from him directly if you ask. He changed the spring to a heavier unit a couple of times to make it better. Different issue I suspect, though... and after hearing it... yeah, low flow surge...

The notches are for valves... if you plan to cam the engine with big lift use the notched pistons. If you are sticking with a stock cam forever, then either will work just fine. I had L28 Valves in my E88 on the original L24 in my 240. It had flat tops that had close to 0.040" positive deck height (head gasket accomodation) and no issues with a stock cam. The guy I sold the engine to put in a fairly large cam and still had no clearance issues. You only know when you clay up the assembly.

I have seen RHD conversions in Australia that are done without the firewall. I believe there is a thread here with one such conversion. What about the pedal box mounting bracket? OH, and I saw a 1974 260 Z converted to RHD at Spa this year where the gent used a racing style pedal box that was floor-mounted, the rest of the coversion regarding the rack and column, etc was done using RHD parts. Actually I believe the Steering shaft and column itself is universal, but the stuff that bolts onto it (regarding key being in the right place, turn indicator and light switch, surround, etc) just bolts on accordingly. Nice writeup, good luck with that conversion. The hidden welds and dissection photos should help anybody doing heavy rust repair in those areas as well. As for the flexing MEASURE MEASURE MEASURE before the first cut, place the body on a solid BUCK, and BRACE THE HELL OUT OF IT! Give yourself room to get to what you need to get to, but bracing and solid support will prevent sag and more importantly "twist" once the boxing member is removed, the whole front of the car will be able to "turn parallelogram" once that firewall is out of there. Bracing up front between the strut towers will limit access, but you should consider it as well. Anything you tack weld on can always be removed and ground off afterwards with little trace. Better to be overbraced and rigid, than underbraced and find your panel wont line up and you have to tweak things to make it fit going back together! Good Luck!

The photos I have in detail are of Z-Specs Cages from a visit to his shop September 29, 2009 (and some earlier shots if I can find them). I will supplant this post with the photos once I get them loaded, and reference the source.

People use the old o-rings when installing injectors? For heaven's sake why? The things are like $3 for the whole body/tip set! That being said, there's always RTV I guess... I love the wordshifting. "Pintle" becomes "spintle"... this is up there with 'irregardless' for me. I must restrain myself when talking on the phone to someone who has continually referred to them as 'pinticle type injectors'... It makes it sound like a groin-based part. "My pinticles itch..." or "Dear, may I see your Pinticles?" I digress...

This is a non-starter. Any pressure rated piping should be constructed out of Epoxy Resin, not polyester. That takes away just about any foam incompatibility. You could use the styrofoam coolers cut up with epoxy resin. Epoxy is also fuel resistant... As for melting it out, depending on the foam used MEK or even Gasoline will work. Same as when you make a car body or boat or anything else out of composite foam construction...simple solvent will get rid of the foam buck once you are all laid up and done. Making air cleaners for triples is a good example (with integral air horns...) As stated above, there won't be any appreciable vacuum in the piping...you are talking maybe inches of water column. I get into this all the time with compressor people worried their intake ducting will collapse if the air filter plugs and the inlet vacuum goes too high... Inlet to the turbo MAYBE there you have some vacuum (then again, only the filter restriction at highest flow...) but between the turbo and the throttle plate, I'm betting you will have positive pressure almost all the time relative to atmospheric once the car is running. If you want pressure rated piping, lay it up correctly and vacuum bag it with some of the UV or Heat Cured Epoxy Resins. Have a friend in the USAF take home some batch storage defunct resisn kits. Not that I would have ever done that...

Actually, the notched pistons tell you someone put notched pistons in it... I have a set of those, NOS, never been in the car, they were a non-us offering and were marketed through the nissan motorsports offices in the USA as a 'performance option' piston. There are more than one E88 as well...

I've got the small primary one, it's the boring of the secondary that will take some doing. Though having a spare would make the initial experimentation less daunting...

A 60's Coleman Aircraft Tug had it... Separate tiller for rear and front. We would set the rears at 45 and the fronts at 45 and crab down the taxiways...

Er...yeah, I don't see 'project z' in the quote. Poor form... nice command to 'never post in any of my threads again' Time to grow up, really. If someone posts something like that complaining about people not offering what he wants... well, maybe they deserve a little slamming. If you want money, put it on e-bay with a reserve, and deal with that mess. Or even better: post it with no reserve and find out how much its worth that day... Compared to another day when it may sell for 28X that much. I know someone here who just bought a HKS Plenum for a paltry sum, and even with shipping to the USA was about HALF what most people were buying them for! It's worth what it's worth the day it sells. That may be more or less than any other time. Neither the buyer, nor the seller knows what it's 'worth' until the deal is concluded. Any other view is masturbation.

HID Conversions in the USA are illegal. http://www.h4lights.com

Wow, those guys can claim my dollar! I wonder if they are out of Wisconsin. The year I missed, Andy gave our distributor shaft to some guys with a 'red 240Z' that needed one. We made our records that year, we didn't need it till next year anyway... As for the comment on the cap being nothing special...argh! Thank you JC... I was about to scream. "Not Available in Stores" is one way to put it. "More Exclusive than the 'I climbed Mount Everest' Club" More people have climbed Everest, than have acquired that hat. One task gets easier as the years progresses due to technology, the other becomes more difficult to get due to technology...you should be able to figure out which is which...(I hope!) (Hint: If Everest grew porportionally taller each year as climbing technology progressed, you would have a rough approximation of what it takes to get the 'Red Hat'...)

I was going to invoke 'Third Dungeon Necroposter' nomenclature till I got to the bottom to see who dredged it up from the bottom of the heap!

http://forums.hybridz.org/showthread.php?t=148957 The options are to vent it properly between the AFM and the Intake Valves as you are metering air that you are dumping overboard for the ricer rush sound, without that air in the intake, (as like the stock setup that pushes it past the throttle plate into #4 intake runner keeping everything from going rich) you have more fuel from the computer based on the AFM being wide open, and the RPMs being higher... You just can't dump it. Many will argue on stock turbos, there is absolutely no good reason to waste money on the aftermarket crap---especially if you haven't gotten added piping volume to relieve. Even then, I've seen multiple stock BOV's added to intakes to take care of that, and the engine is silent on shifts! No attention getting ricer "poofta" noise!

Yeah, Tyler... The BOV is not the emergency relief valve. The BOV in stock form is in the #4 intake runner, and uses the vacuum on the manifold present on drop-throttle to accomplish evacuation of the J-Pipe through a FAR smaller orifice than you would need dumping the same pressure and volume to atmospheric pressure. BOV's operate (all valves in fact...) on the principle of differential pressure across the valve. Venting to the manifold has 10psig air in the J pipe venting to near 25" HG "Vacuum" in the manifold. That is 2.2 psia. So you are venting 24.7psia (10psig) in the J pipe through a 1/2" orifice to a 2.2 psia area meaning that 1/2" orifice has a 22.5 psi delta pressure. Using standard engineering calculations you can determine flow through that orifice. If you use a 'standard' BOV dumping to Atmosphere you are dumping that same 24.7psia to a 14.7psia area---a delta pressure of only 10psi! You can see just from that example that a BOV, to function as well as a STOCK BOV positioned in #4 Runner will have to have at least 2X orifice size to give comparable results. That means maybe a 25mm BOV, but it all depends on the flow coefficient across the valve. With a lot of the crap out there, you will need a significantly larger valve size. It is possible that a .5 orifice with almost a 23psi delta will be flowing far more than a 1 or even 1.25 orifice with only 10psi across it. "This has all been discussed before"

Post em if you want, saves me the trouble! LOL Some of them are out of focus...I don't like my new 'mini camera' as much as the previous model I had. Small lenses suck.

Garett is making integral dual turbos with unitized castings more for flow required at boost. They also have twin compressors on single turbine drives that have CR of over 3:1 meaning 45psi. The deal is flow, you need a compressor of X size to flow X CFM and there is no way around it. Unless you run tandem compressors from the same turbine... And that kind of blows the twin turbo argument in the water...because when those super-high flow turbos show up on the aftermarket you will have a LOT less packaging headaches. Twins on S30's were deriguer in the 80's simply because compressor and turbine wheel technology were not up to the requirements. You needed twins to have any sort of spool on a 600+ HP car. By the mid 90's they had passed into the history books simply because of the advances in 5 axis machining. The ability to lower boost threshold to lower rpms is materials and bearing related. BB Turbos are running 500 rpms lower thresholds than the older sleeve bearing designs, ceramic and titanium lower inertia and are stronger, 5Axis milling means thinner blades so more air flows through at the same speeds as before... I could get 17psi running a .43 housing at 1700rpms (1982 Technology), and it was all in by 5500, but really the stock cam worked in conjunction with that as well. I would be really interested with a larger wastegate hole (or external gate) and the new compressor wheels what I could do with that same setup today... I suspect 6500 rpm power peak, and that same boost available from 1200rpms with far more HP potential. The surge curves of the new wheels allow things never before DREAMED of even in the late 80's when the the word came from on high from Moses Bell out of Texas. Well, the bush was burning when I sat agog at the Garrett (Nee Honeywell/Allied Signal) R&D Facility in Lomita and it said unto me: Worship not at the altar of Bell, and learn well the lessons of Turbocharger Research and Development, for it will lead you to a land of smoking and burnouts... I digress... how did this turn into a Rotary Thread? LOL

Now... about increasing that secondary bore size to 48-50mm with that dinky primary... All the parts exist, but is the body capable of taking that bore. That is what we all REALLY want: that dinky primary body for 85% of our driving. Do you guys realize how big a cam you could run and still get a decent MAP signal because of the small incremental changes from that primary barrel? Tuning would be a snap and the fuel economy would be FAR better than the same setup with a 60 or 65mm throttlebody, simply due to the resolution you get at partial throttle. It's why I've eyed these for some time. I want the smallest primary body, with the largest secondary possible. For a turbo car this would really be ideal! For a heavily cammed car it would be even better... Anybody remember the Dodge Thermoquads with the miniscule primary bores and then twin 2"+ secondaries? I put that intake and carb on a Dart with a 318 and got BETTER gas mileage than with the original 2bbl (which had FAR larger primary barrels!) Same forces are work... You want resolution for 85% of the driving you do. The rest of the time you want least restriction to flow possible. These dinky primaries do it...we just need a bigger secondary for when the WOT urge arises.

Panzer, e-mail on the way to you through the ether...

Sounds Good John, I'm running to an emergency job in Garyville LA at Marathon Oil, so it will be a day or so before I can load up the photos. So much for having two or three weeks in the office before going on furlough. Seems the only time I'm getting off this year is when I'm not getting paid for it! DAMN!

The photos are 16MB, if gmail accepts that much, I can send them from my work e-mail to you ace. Otherwise I will cut the message in half and send two. I got to rush to the house to cut up a tree laying on my cars, and hten pack for Louisiana and an emergency job at Marathon Refinery in Garyville. I'll check in when I get the time and forward as appropriate.