WizardBlack

Sorry, but that is completely dependent upon specific turbos. Mr MacInnes doesn't consider the bearing drag of two turbos versus one and countless other real world things. Two turbos that flow the same as one larger one is difficult to find. In the real world, you get something close. Some cars are a better fit for a single turbo and others for twins. This is from a PEAK HP point. In my experience, rotational inertia is less of a deciding factor as bearing design and finding turbos that fit the performance envelope of the engine. A sequential turbo setup is nifty because the engine can run on one turbo to spool it at lower rpm and has some low down grunt. If you want the big power, you rev it up higher and it will open up both turbos. When you are rev'ing up to hit both turbos, you will have two spools; one as soon as you roll on the throttle (at low rpm) and another when the ECU opens up the second turbo. After that first gear, you just keep the revs up above that set point for the second turbo as governed by the ECU. Just as 1 fast z has said, some ppl prefer the sequential setup and some don't want the double spool, etc. Like most things, it's a preference, I suppose. Sequential turbos are usually ditched in favor of a simpler system. Note that not all twin turbo systems are sequential. Some just have two turbos (I usually refer to them as parallel). Likewise, not all sequential systems use two turbos of the same size. If you want to look at the Supra system, compare the HKS twin setup. It doesn't really spool any faster. It is more expensive (heavier) and cooler (to some, I suppose; I know someone who bought them for that reason). Again, in real world, you have a limited set of turbo choices and sometimes twins are a better fit. IMHO, it is very rare that twins are better on an inline engine.

Diffs don't get that hot.

Glad to see you've been able to make some progress toward your solution!

Yes, I have essentially done it. I have gone through the entire harness, pulled it apart, identified everything, removed what I didn't need and replaced that which was left that was questionable. The S30 isn't a very complicated system. My chassis ('77) had a harness running to the rear for taillights, fuel pump, fuel level, etc. and one to the front for lights, signals, fan, etc. I definitely recommend changing over to fuses versus the fusible links and beefing up your grounding system as a good (read: reliable) platform for engine management. I don't daily drive my car, but I have done likewise in the past. It won't be that bad for the chassis and it will certainly run fine once you have it set. Make sure you get a manual (Chilton, Haynes) on the car, but if you are familiar with wiring much, it will make sense pretty quick.

How about concentric grooves in the valves? This guy machines grooves on the backside of the intake valves. He also actively modifies heads with the Somender Singh (or whatever they were) grooves on the combustion chambers. A few other things as well. http://www.allpar.com/fix/holler/valve-prepping.html

Well I've pulled it apart. How might I tell if the retainer groove is borked? I have the hardened seats, so I hope I am good there.

Wet sleeve?

Just as an update. I got into the head a bit to clean it up and noticed a few things. First, I can manually spin some of the valves while they are on the seat. Second, I can press down on a retainer with a flat blade screwdriver and press it down a good 1/4 to 1/2 inch. That is without leaning over top of it, etc. I guess there's where a lot of that power went. I can't hear a dang thing when it's on the road with the whining diff (soon to be fixed also). I ordered ISKY springs and retainers. I'll hold off on the cam until I have an intake manifold on the car.

Yup, I already have all the parts on the way, but just curious if that was normal or not.

Post a pic if you can? Use a punch to start the bit spot.

I have a question about the timing chain system since I suspect an issue. Basic configuration of my car: '77 L28E with N42 / N47 setup Holset with Megasquirt and EDIS-6 I have been running 15 psi and it holds together OK, but I suspect it's a bit weak. It would probably just keep up with a stock STi. Given that I weighed it and it's 2500 pounds dead on, it has a good weight advantage. I have been concerned that the P.O. didn't get some stuff right with the headstuds and HG, so I decided to pull it apart. With the valve cover off, I can look down to the chain and see that the chain running along the straight guide is loose and doesn't lay along the guide. I can reach down and jiggle it; it is LOOSE. Is this common? Correct? I turned it over and over and it shows that the notches are lining up correctly according to the Haynes manual, but that amount of slack is disconcerting. I assume this would retard the cam quite a bit and play heck with spool and powerband. This is the first and only Datsun I've played with so nothing to judge by.

Find thread and length specs and see if any in ARP's catalogue will fit. They're pretty good about helping you find something (from another application) that will fit if you call their tech line.

While I would never try to drill and tap (and JB weld) on a block, that specific hole was gunked with exhaust on my NA->turbo N42 block. What gives?

Good gawd, welcome to last year. I remember seeing that thread, but it seems to be pretty stagnant. I guess everyone is kinda in limbo working on getting stuff up and running to try it.

I assume some of you have seen this stuff? Nice to have another option. Q45 or S1x hubs and adjustable camber at the hubs, etc. Look through their differential mounts, lower control arms, etc. Discuss? http://www.technotoytuning.com/racing/ Mark

LOL, sorry. It was late and I was thinking solid axle.

Yeah, they refer to the injector going into DC mode essentially. No more square wave; just solid 12V.

You may also want to be sure your tip is not contaminated. If it is, your arc is way too diffused and will only server to dump massive heat into the part before it starts to weld together. Lay the tungsten tip on the table and tap it lightly with a socket or something. It if shatters, then it's contaminated. Re-grind it down and start over. If you are like me, you spend almost half your time at first regrinding your tungsten tip after it touches the pool and contaminates it.

RC Engineering has a really nice calculator to figure out your injector sizing needs.

Some cars do. STi's float pretty darn high from the factory (like, low 80's) and a few bolt-ons can push them to 100%.

Crappy injectors will flutter much beyond 80% duty cycle. Good injectors can push a bit past 90% duty cycle (EVO and some RC Engineering Injectors I played with). Some injectors will max out and stay stable at ~100% duty cycle (Subaru STi Injectors).

It's the same thing as saying it doesn't matter how small your exhaust is as long as you actually hit the power number you need/want. Bigger hose (to an extent) will make it easier on the fuel pump to hit the demand you place on it.

Megasquirt.

I have 560's and use PWM on my MS. No problems with 800 rpm idle. It runs closed loop at stoich.

You can probably make one of plate metal of the proper thickness easily enough.