Tony D

Why? Overdrive is almost identical.

Not here, elswhere... Actually having necrophilia mentioned in my signature line probably wouldn't be an issue here, knowing some of the moderators!

That's called a "ZX"!

Just finished breakfast matter of fact... now to ruminate over my day's-banning due to simple Necrophilic References. Some people just don't get black humor. No matter how mean-spirited the intent! I mean, if I WANT to be mean, I CAN be mean. Give them an example and they just get all out-of-shape!

Yeah, the Singh Combustion Chamber ( which I have posted photos of previously ) is more geared towards 'grooves' in specific locations---like along the quench-pad to combustion chamber area---than circular punch marks surrounding the exhaust valve. Sadly I know what was happening on that head, I've seen it before. As I said, I'd not use it there are too many fish in the sea to risk that kind of 'work' failing. Short of pulling the seats and installing a new set correctly I would say the head is relegated to "shelf life and lookin' at"!

Uh... yeah... "The security of the exhaust valve seats"!!!!! Seriously, why did they feel the need to stake the seats in that fashion? Not enough heat on the head and no N2 to shrink the seats on installation---so they figure "punching them will tighten 'em up good 'nuff!" I would have serious reservations on using that head as anything other than cutting up for porting information or other experiment. I mean, if you yanked out the valves and made sure they were installed correctly then I might use it... But with those punch marks there... I'd wonder WTF they were trying to shortcut!

The pedal cluster unblots as an assembly, it is near a spot-welded chassis component that runs 'through' it to support the steering column, but the pedal box will come out separately. As noted, it's kind of a PITA to remove as the dash comes out to access it the easiest...but it does come out!

Well, I see it's too late for my warning of "Don't forget to slip the section of Sch 80 Pipe over the lines to keep them intact should the clutch come apart..." Make yourself a 1/4" thick plate, and bolt it to the chassis to cover your lines in the vicinity of the plane of rotation...

Oh, I assumed you ran aftermarket A/C like I do in those temperatures. You do remember my stories about going 110mph across Iowa in 104F and 90+ R.H. with a 70F interior temperature and a temperature gauge right left of center??? Trust me, if you can keep your engine cool in SoCal/PHX during the summer months, you got a 'cross conuntry cruiser' with A/C on full blast! I know I did!

Make that 32+mpg on L28eT's Mapping isn't a big issue---when it goes to light cruise lean the heck out of it just like stock. Weight is the same as they will have the same equipment, this is a non-issue... Look to General Motors and their GENIII3800 in the Bonnevilles and other humongo cars, which regularly get mid 30's at highway cruise. Torque is your friend, and that nod goes to L28. And if it's turbo, even more torque.

Methinks the Z31 Guys are huffing the lacquer again. Those are seat-stakes and nothing more! Personally would scare the hell out of me if they think staking the exhaust seats like that will do anything material. Singh combustion chambers aren't accomplished using a center punch in the vicinity of the exhaust valve seat! That's a wild-arsed guess to say those are Singh Chambers...and a poor one at that! Singh-Chambers are very distinctive, and if you google it, you will see what I'm talking about. They are not cylinderical punch marks, and nowhere near the valve seats!

TDC is determined between timing marks and actually indicating the engine. Read the FSM (81 Turbo Supplement) for which marks are TDC on that unit. I had some stuff on that when I used that setup on my MS---it's on sharkie73z's cardomain page someplace---you can check it out, only 14 pages to sift through. Mostly useless information anyway.

Lets compare southern california in april to where I currently am working: Southern Thailand in April. 32C is 32C right? Unless one is 20% Relative Humidity, and another is 2-4C hotter, as well as 90% Relative Humidity... There's "Hot" and there's "HOT"... Frankly, handling Mexicali at 50C+ in July and August is easier on me than Thailand at 40C any time of the year.

Yeah, I was thinking a nice late-model for my Fairlady Z, which has a clapped out 3.9 R180 in it now, so the Torsen setup would work nicely. And now they are 'in the scrap system'... have been waiting till I red the technical specs on the 07 STi! Eventually it all trickles down to us bottom-feeders!

Actually I believe the diameter of the piping is inverse to dB. Larger usually means quieter. This was the way it was on the Corvairs which basically had mufflers right on the header collector and then out the back. The larger diameter exhausts which you thought would be louder had a much lower and mellow tone. Smaller diameters on the Z seem to have a 'snarl'---much more 'pop' rather than a low-throated rumble. It may be where the auditory effects are masked. People find an F15 at idle wildly loud (and it is...) but mostly because the noise is RIGHT in the irritating zone of human hearing Hz - Wise. Perhaps the larger diameter pipes will 'meter' as loud, and it's just the human ear that 'seems to think' it's lower noise. And really it's that perception that will get you the ticket! If it 'sounds loud' it is, and the ticket gets written.

LOL, yeah, I was there. Though I would debate 'hot weather'...

I would disagree: tune for those hot days! You will only be rewarded by being able to drive in any weather without making excuses. I would drive out to Palm Springs to work the long grade back into Riverside during the hottest parts of summer. As a result of me tuning at those temperatures, I had absolutely no other issues the rest of the year. Then it was something like 110-120 (and don't even get into macadam thermal layer ingestion temperature! I was sucking in air at over 160F to the turbo in some cases!!!) If you add methanol, that kind of temperature won't be a deterrent, but then you have another tank to fill and worry about. I didn't have methanol on that build likely I would today since the injection technology has progressed so much. I had it (water and water/methanol actually) on the Turbo Corvair...and it was tuned on the same grade, at the same time of the year! Tune when it's hot, with the A/C on. Either you reveal your cooling systems' shortfalls, or your tuning shortfalls. Either way, in the long run you will be rewarded with something that is long-term troublefree.

That's what I thought on the 2007+ units, thx!

81 ZXT Stock Dampner and Timing/CAS wheel. "Saving Weight" is not applicable to the harmonic damper on the engine--serious false economy there, HUGE mistake!

I got everything to do that(again), but it wouldn't be the same as the wind-tunnel as you would have to restrict yourself to doing it on the same engine or car meaning breaks in time to do the changes. Renting a dyno for a day is easy enough, and not that bad if you can do it during 'off-peak' times, but effectively changing an induction system quickly... and then optimizing it. Probably the best way to do it would be to run and tune each setup separately over a period of a couple of weeks/months, and then shelve the components in prep for a 'back to back test' which could then be done over the course of one or two days. Technically the results should be the same but reaccomplishing the tests back-to-back on the same dyno, on the same day would dispel the 'dyno drift' argument that would inevitably creep up over testing individual components separately at different times of the year, etc. But I do have all the components, and more than enough 'spare cars' with L24's L26's and L28's in them. Three chassis ready to prep one with each engine. And I know an amicable dyno operator. Now to get some magazine to accept the article... And get the time to do it...

Sparco and some of the other Silicone Vendors have 'tree' hoses--that is standard size turbo inlet sizes with a 'smaller branch' of anywhere from 5 to 25mm diameter. I made mine from a section of 3" muffler tubing. Had a mandrel bent 3/4" pipe that I made a penetration and welded in place. Then connected the muffler tubing to the turbo, and the 3/4" pipe to the blowoff (recirc) valve... The front portion of the muffler tube was like a CAI setup, and eventually went to a K&N Cone Filter. The 3/4" pipe pointed to the turbo wheel, so the air blowing down poofed to the turbine wheel to hopefully keep it spinning faster with no force coming from the turbine side on drop-throttle. My understanding is this is how the old 917's were plumbed.

It will give you that. Mine would make 17psi at 1700psi (where I ran most of the time) At low boost on 10psi I could get that off-idle really. From a standstill with a clutch dump I would have 17psi if I went WOT simultaneously. I would go positive pressure when free revving with the smaller surge tank. This didn't happen on the larger tank. Frank 280ZX has a similar setup running 10psi on triple blowthrough webers making 231hp to the rear wheels, and his spool is very similar to mine. On his ITB setup with megasquirt if he 'fast idled' the car at 1700 he was making 2-3psi (AT IDLE!) I think you will really like the response from the engine. For a daily driver it will be great. I loved mine.

This belies the physics of what is really happening and is misleading as to what is really what is going on. PV=nRT, boyle's law says the higher pressure you have the more heat produced. It's nothing about a bottle neck in the downstream it goes directly to the pressure ratio and efficiency map of the turbo. If you walk outside the most efficient area of the compressor map, you make more heat per psi produced simply through inefficient compression and internal recirculation. Add to that higher pressure (meaning higher pressure ratio) means that more heat is also produced. Heat is produced by pressure ratio, NOTHING ELSE. This is the physics of compression. The FLOW portion puts you on the map in an efficient or inefficient portion of the efficiency islands. The PRESSURE component gives the basic heat generation. It is straightforward on a 3:1 Comp ratio that you will make X heat at an 88% efficient compression area of the map. Move to the 78% portion of the map, and you will make X heat + the additional heat generated due to being 78% versus 88% efficient in compression. This can be very significant. This is a quadratic equation with the efficiency of the stage of compression a fractional exponent, but the math is something anybody with high school pre-calc or algebra 2 could work out, really. The same thing goes for any compressor. What you do with the "crank up the boost mentality" is move the point on the efficiency island where the compressor is operating from one of high efficiency, to one of lower efficiency. If you run vertically on the compressor map, you would get more heat at the SAME pressure due to the efficiency loss. Add a vertical and horizontal component to the equation and you end up set for poor efficency. Rarely do you move to the right on the compressor map in terms of efficiency, the 'crank up the boost' people move up, and to the left on the map almost universally. And look at a turbo map for efficiency islands and you can see the dropoff plain as day. Through engineering, they bias the maps wonderfully to compensate for this (compare a turbo map from 1970 and 2010 to see the change of the island shape!)

Valve float? What's that? Seriously, we haven't floated the Bonneville engine yet... Someone would have to use a very unstable cam profile to make an L-Valvetrain float!

Yep, detonation damage from inaudible and what most people think is 'harmless' detonation long-term. Remember people say to check your plugs for signs of silver (aluminum) after some detonation---now you know where it comes from! Either the head, or the piston crown. Ceramic Coating may be the least expensive alternative to salvage the head, but the damage between the seats won't be helped by ceramic... Lost material there means the chance of a lost seat eventually.