BobsZTwins

Actually, the mixture going into the turbo is pretty cool, having just been atomized in the carb. So the mixture isn't as hot as you'd expect. This isn't the case with EFI units where the air is compressed (heated) first. That's why an intercooler is needed to both reduce heat (potential for detonation) and to increase the air density. I also have the MSD boost retard system to dial back the spark advance as psi & temp rises. When Scarab was selling these engines they were advertised at 425hp @ 10psi. I've seen +/- 15psi and I can tell you it's a neck snapper. After I get my valve stem seals replaced I plan to dyno the unit to see just what it's putting out.

You're right about the operation of the unit but boost isn't limited to 5-6 psi, I've seen 15 on mine (cool humid day with retard at 6 degrees) and routinely hit 13 psi. It's just at high boost you tend to get a jolt when you back off unless you push the clutch in at the same time.

Thanks for the feedback, I have to agree about the valve seats/seals. Especially on the right side where the turbo sits right next to the valve cover. I'm sure residual heat after shutdown shortens the life of the seals. The system is a pull thru and I know I'm getting plenty of fuel pressure, I just rebuilt the elec pump and tested flow at the carb. But the bogging must be the accel pump. I think I'm gonna put it in the shop next week, I wanna feel the full pull of 425hp again! Thanks!

This is the Scarab Stage II 425 hp setup. I have one on my 260Z. Does it come with the boost control, bypass, crossover and downpipe? The downpipe for the Scarab only fits in the Scarab engine position and would need modifying to fit in the JTR position. Any gaskets come with it? Let me know if you need pics or info. BOB'S 2FORTZ '72 240 L28 3XWEBERS '74 260 TURBO 350

I've got a noticeable skip and an occasional puff of blue out the tailpipe of my Stage II Scarab motor. It's the single turbo chevy 350 rated at 425hp. I've tried all the usual: new plugs, wires, cap, rotor. Checked compression, it's around 135 except one's down at 125, not too far off. Plug threads are oily but plugs aren't fouling. No telltale sounds but I do have a bad hesitation when I romp on the gas, no problem if I ease down to the floor. That sounds like an accelerator pump. But it's certainly down on power. Any suggestions? Anyone know of a GOOD engine builder/rebuilder in the Jacksonville, FL area? I really want to get the car screaming again! Thanks!!

I've got a 260Z with a Chevy 350 bolted to a T10. I'd like to upgrade to a WC T5. The block is a 4 bolt main with a split rear main seal ('69-'80 vintage casting). Any known problems with bolt-up, clutch, etc.? Thanks for any advice!

Have you checked out the article in the Summer 2002 edition of Sport Z Magazine? Lots of detail and pics. Uses parts from MA, Ground Control and Coleman Racing.

1/27/01: Sorry for not responding sooner, it's been pretty hectic at work the last two weeks, no time for my toys! I am seriously interested in the gear set. I will try to check on the bolt size in my diff this weekend and let you know if I can use yours. Thanks! 1/28/01: Can you tell from the part number what size bolts are used? I found a receipt for the Ring/Pinion currently in the car. The part number is 38100-P6400. I saw that the part number for your for sale item is 38100-P6200. With the part numbers so similar, could that mean mine are also 10MM?? [ September 28, 2001: Message edited by: BOB'S 2FORTZ ]

Thanks for the feedback. Since this conversion was done +/- 1979, the diff is likely 10mm, so first I'll check that out. As to 3.36 vs 3.38, my mistake! BTW Ross, how much are you asking for your set?

I have a Scarab bellhousing....but it's bolted to a Scarab Stage II motor, sorry. I haven't seen one of those pieces for sale in a long, long time. I'd go with one of the other options posted here.

I've got an old Scarab conversion with an R200 LSD. The previous owner had to replace the Ring & Pinion and all he could find was a 3.7. I've got a line on a 3.38 but I don't know if they are interchangable between open and LSD units. Anyone know for sure?

If you want to run the dust covers, you definitely need to trim them but they're not necessary. You do not need any adaptor for the caliper but if you want to run the '84 vented rotor you need to have a spacer fab'd to go between the hat and rotor. You will also need to trim the diameter of the rotor by 1/8". As to whether the Toyota calipers provide better performance than the stock with performance pads, it depends on what type of racing you plan to do. If it's just autocross or some street racing, stock's fine. If you plan to run hot laps on a track, you need the upgrade. When I ran 3-20 minute sessions at Willowsprings with stock calipers, I ran outta brakes by the start of the 3rd session! The next time, with the upgrade, I didn't even have any fade. But, even with an adjustable proportioning valve wide open, I still locked up the fronts before the rears. Still looking for a solution for that one!

I think a refresher on turbo's for FI engines may be helpful for some. Check out "Super Street" Magazine 09/01, pg. 147. In FI engines the wastegate, on the exhaust side, determines max boost pressure. The blow-off valve is on the intake side of the turbo, it's function is to reduce or eliminate compression surge, which occurs when you get off the throttle. Once the throttle plates close, the incoming air has nowhere to go but back to the turbo. At best, this slows the turbo so you get lag when you're back on the gas. At worst, it can damage the turbo. However, on my Carb'd turbo V-8, the carb is before the turbo so there's no blow-off valve. The Wastegate can be manually adjusted to +/_ 16 pounds.

I did this upgrade last year. You need 4 bolt (1984) 300ZX non-turbo rotors. They will need to be cut down in diameter about 1/8". You will need spacers made, the thickness depends on which "hats" your car has, there about 4 different dimension combo's out there. I did a mock up using large washers then asked a friend with a machine shop to fabricate from the mock up. It fit perfect 1st try. I'm in the San Gabriel Valley if you want to have a look sometime.