SleeperZ

You are close. That's how I calculated it though, just the same percentage of air as fuel. 3-1/2 inch diameter is the appropriate size, any fine tuning I performed was with fuel pressure adjustments. I am currently running 43 psi base fuel pressure.

The Z31 turbo and non-turbo are the same size as the 280ZX turbo, at 260cc/min. The 280zx non-turbo are something like 180cc/min. Keep an eye on eBay, I got a used turbo distributor for $10.

Drax is right, the BOV operates on a pressure (vacuum) differential between the plenum and the other side of the throttle. I've heard of some valves that are too sensitive, and the vacuum of idle is enough relative to the atmospheric pressure of the intake to cause them to be open at idle, causing problems (big ones if it's not plumbed into the intake). My DSM BOV is closed at idle, and only vents on a throttle lift, where the cracking pressure is higher than idle vacuum alone. Hope that made some sense.

It sounds to me like you need a good engine managment system, injectors and a better turbo. The stock EFI unit was NEVER intended to be used that way, and you are damn lucky nothing has exploded on you running that lean with stock non-turbo injectors! And running that hot with a stock turbo! Please don't take it the wrong way, but I don't you can tune this system. If I was to guess, I'd say you can't be making more than 220 hp to the wheels. With a stock Z31 computer, stock turbo injectors, intercooler and a better turbo, I put down over 250hp at 15 psi of boost (stock motor). Others have put down the same with stock turbos running only slightly higher boost.

The newer cars have "bolt-on" exhaust systems. On a Z, there are so many variables you can't buy a bolt-on system. That muffler is 3" in, 3" out. You have to mess with exhaust hangers to locate in the right spot, as well as get 3" piping from the turbo back. I built my system myself, with 1 custom welded piece. Everything else "bolted" on after many cuttings and trial fittings. I used band style clamps to hold the pieces together, and it dis-assembles fairly well.

Dynomax part number 17221 Summit part number WLK-17221

I'd be curious what your mixture is across the rpm band at full load. Your ignition timing is set to 2* BTDC? With stock turbo EFI, that setting is 20* BTDC. Or are you just talking about your BTM setting? Either the timing or the fuel mixture could be keeping the torque low until you hit full boost. I can't believe the cold start injector is doing much for you... You are running a stock fuel system at 25 psi? That sounds dangerous actually - you won't get but 250 hp, and you can max out the fuel injectors by 12 psi, or 14-15 without an intercooler. I really can't imagine just the exhaust addition hurt performance - it sounds postively UNrestrictive.

That sounds OK, but they didn't rev the motor up much... That should be the same muffler I have, but mine's not stainless, and cost just $65 from Summit. I really like the WOT sound my Z has now.

I'm using the N/A dampener. They are the same size, about 5/16".

Stock EFI vents the crankcase before the turbo, so any oil blowby will collect in the intake. If it's a lot of oil, it could be the turbo seal, otherwise it's normal.

DaneL24 - you are absolutely right about the torque and Honda engines. The Integra Type R runs a diff ratio of something like a 4.38 stock, and JDM higher than that, like a 4.55. Even higher ones are available. I was at the strip last Friday and ran into a supercharged S2000 (Vortech, with A/L IC). He was putting down 300hp to the wheels, and kept breaking into the 13s (he had no helmet or roll bar on his convertible). An impressive little car, and that supercharger setup was very nice.

That looks really nice.

The ECCS rev limiter is a pain in the a$$ - it cuts fuel as well as spark, and has a significant recovery time. Lately, to spare my clutch, I've been launching at 3500 rpm. Below that I'll bog, much above that my clutch will slip as I put load on it. With my new (to me, it's used/broken in) clutch, I expect to launch at 4000 - 4500 rpm.

I've examined my fairly closely, and it is not in the least restrictive. You can see daylight through the thing - it just has a spring loaded diaphragm inside to smooth out pressure pulses. If yours is bad, it's way easy to pull one off another car in the scrapyard....

Not sure if I should start a new post or not, but what do people think of the rev limiters built into the MSD box? At this point, that would be the only reason for me to install an MSD - to get a rev limiter I can launch from, to help consistancy for drag racing... I've heard the engines can load down with fuel on an ignition based rev limiter. The MSD is supposed to avoid that by only pulling spark out of a cylinder once, and letting it spark the next time around, but how well does it work? Will it depend on how much throttle you are giving it?

400 whp is no where close to the potential of 290 cfm per cylinder! What James is saying, with crude numbers, the P90 head can be capable of flowing enough to support over 700 hp to the wheels!

Wow! Great info - now we are talking big power!

I had a 2-1/2" in 2-1/2" out Flowtech Afterburner. I know, cool name, eh? It sounded sort of mean at idle, but it just wouldn't flow up top. And it resonated badly around 2500 rpm. But I have a turbo car that puts down a fair amount of hp, so no surprise that it dind't flow. Personally I got real tired of the chambered muffler - I prefer the Dynomax, sounds just as mean without the resonance, and flows much better.

My L28ET with 3" exhaust (rear exit, Dynomax muffler) will build boost as soon as you load the motor with the clutch - 3500 rpm launch, practically zero lag. What turbine are you running that will drive 25psi of boost? It sounds like you've optimized for top end flow, and there may not be anything you can do for your lag.

Wow, good job! I was originally going to buy one when they were first developed, but when he went with the larger rotor I thought "no way will that fit with my 6 spokes..."

Sweet! Nice job Scotty!

I never connected a speed sensor

Works fine with just an air regulator. No problems whatsoever.

The power peak is in the mid 5000 rpms. No reason to rev it higher than redline, except if you want to break it.