SleeperZ

I stated on your other post I think a RRFPR needs to be tuned using a wideband and a dyno. Unless you can log fuel pressure while driving, there is no way of knowing what pressure you've set the thing. And I can point out ScottieMIZ who is still running the AFM without a RRFPR and is well into the 12's, with 420cc injectors. And as far as I'm concerned, there is nothing wrong with the factory regulator unless you want adjustability.

My opinion again, of course, running both is a bit excessive, expensive, complicated and rather pointless. If you want a drag or road car, a good efficient turbo system will out-perform it. For autocross, you'd be better off with n/a (or a straight roots charger). On the other hand, it would make a good show car. Don't think a turbo doesn't have low end - look at my dyno graph in my personal gallery, and tell me where my peak torque is.

Or was the question just supercharging a L28ET engine, meaning replace the turbo with a blower, roots or otherwise? IMHO the low compression would work best with a roots, it'd be a dog at low RPM with a centrifugal.

No doubt, that's what I run. It seemed to work fine with the factory regulator as well. But "best" is a practically wide open question...

I'm not sure I did misunderstand you. All I was asking was, how do you know that's what the AFM does? I've heard it before from other people, but I don't always believe what I hear. That is a large part of the load/rpm curve that would be missing if the AFM were wide open at 4000 rpm. The reason I disbelieve it is the AFM is not sensitive to rpm, it responds to airflow. So it would max out way early on a boosted car, and I know they don't run bad at WOT. But I don't have much experience with the stupid flapper POS, as I upgraded to a Z31 MAF before I started seriously tweeking the boost. In short, you are correct, all the input the ECU would have is rpm in order to fuel above a certain airflow level, so once you hit it with more boost (or intercooled it), you would run more and more lean with increasing boost. If so, you'd want a RRFPR and a darn good fuel pump. But I wouldn't run one without a wideband and a long dyno session.

Man-o-man, they must be using Tardis technology to squeeze that thing in! Lol, ON3GO, "Jackstand Racing"

Keep in mind you may not see much gain if you are regulating boost pressure at the compressor housing. The reason my setup netted me so much more power is the manifold pressure was the same before and after the IC install, not the pressure in the compressor housing. So I may have had the same boost in the manifold, it was much cooler (denser), so more air = more power.

An intercooler DOES add power, if your fuel system and EFI can support it. I was running a high 14 with my stock turbo, 10 psi. I added my intercooler without changing the boost level (at the manifold), and ran 0.5 second faster with the same 60' time. I also gained 4-5 mph trap speed.

When you get that powerglide in, I believe you will run 10s, no problem.

Hard to believe the exhaust will create any meaningful vacuum (better plumb that baby AFTER the turbo ). I've heard of evacuating the crankcase with the intake vacuum, but of course that won't do under throttle. Better yet, run a vacuum pump, then dump the vapors into the exhaust.

Looks good. BTW, the stock downpipe is 4 bolts - fairly standard.

I had just the opposite experience. My traps have been consistantly 2-3mph higher this past summer with the 3.54, after replacing the 3.90 in July. Maybe it's the way I drive it.

Well Alex, I was going on the assumption his power goals were somewhat more modest....

Lol! 72lb injectors for 350hp! 550 cc injectors a weak spot? Give me a break - I run a safe 350hp right now with 370 cc injectors. I can see why "zcars" make your head hurt. I think the 0.63 a/r with a stage 5 turbine would do fine with your cam setup as well, and you should be able to build on that for 400-450 hp easily.

That's ok. Personally, I'd never run a BOV, preferring to recirculate. But I know lots of people who just vent it. It's not good for driveability, but it still keeps the turbo from stalling.

IMHO, the VG motor will be better off with a 3.54.

The MAF may not be calibrated or be able to withstand the heat. It's also a bit large ID wise to be installing in a turbo outlet. And you can always have a BOV vent to atmosphere.

Whatever you dis-assemble to remove and replace the turbo. There is a manifold gasket, turbo inlet gasket, turbo outlet gasket, you know...

My '78 weighs about 2620lb with 1/4 tank. I have an intercooled turbo L28, a T5, and a heavy 3" exhaust. I've stripped the A/C, the bumpers and supports, and lost the spare tire. I also run the factory ZXT wheels and fairly small tires - light where it counts, rotating and unsprung. otherwise I have all the stock stuff excepting ZX front calipers and Z31 front rotors.

For the '78, the pump relay is in the engine compartment on the right side with all the other relays.

I agree with the above responses assuming you are using an L28ET. A turbo V8 like a SBC 350 would probably put a 3.54 to good use as well, but an RB or an SR20 motor (much higher revving) would be better off with the 3.90 or 4.11, or even higher.

Whichever way you go, make sure to plug the pop-off valve in the manifold, and get a boost gauge in your dash.