Blown issues!!!!

[Procharmo]

I see 15" vacuum at idle when my boost vacuum gauge is teed of the vacuum line from my carb spacer to blow off valve.

I see 0 lbs boost when revved to 4000 rpm. (Gauge goes from 15" vacuum to 0lbs and then drops back to 10" approx.) Even when BOV's have been replaced by straight pipe and boost gauge is connected directly to carb spacer port.

I see boost referenced fuel pressure rising with rpm. So I tee boost gauge to line from regulator ro carb bonnet. I now have 8lbs-10lbs @ 4000rpm above the butterflies. But no boost below.

Procharger blow of valves never fully shut.



Do I have a leak? Could it be manifold to heads, Carb to Manifold.

I have -4 AN fittings from carb spacer to BOV, boost gauge, Carb bonnet, Areomotive 13202. I have checked/renewed connections from carb to vacuum advance, Turbo 350 actuator and from carb to brake booster.

AFR heads and Air Gap rpm manifold were installed by an autoshop with tons of silicone sealant visible. The rest was DIY installed.

Should I remove the BOV's (major air turbulace) and try the soapy water around the carb base and inlet manifold perimeter?

[Blown353]

No issues, perfectly normal.

Free revving to a steady 4K rpm doesn't open the throttle blades enough to allow the supercharger to build any boost below the throttle blades.

During your 4K free rev, the throttle blades are just barely open so you aren't getting boost in the intake as very little air is actually going into the intake & chambers; however all that air is "stacking up" above the nearly closed throttle blades which is why your fuel pressure is increasing because it is referenced from the hat above the throttle blades.

To build boost in the intake with a centrifugal requires not only enough supercharger RPM to move a sufficient amount of air, but also that the throttle blades be sufficiently open that they are not a restriction.

Hook up the bypass valve again, and go out and put some load on it (i.e. larger throttle openings)... you will see boost.

[GBodyGMachine]

Ditto

[Procharmo]

OK thanks guys.

I think I'll just try it out at 6000 rpm and see what happens. I admit I'm afraid of blowing it up after spending so much time installing it. I'll add a few bottles of octane booster and a tank of 99 octane pump gas as insurance.

Cheers.

[camcojb]

OK thanks guys.

I think I'll just try it out at 6000 rpm and see what happens. I admit I'm afraid of blowing it up after spending so much time installing it. I'll add a few bottles of octane booster and a tank of 99 octane pump gas as insurance.

Cheers.

Just so you understand, don't try to see boost by revving in neutral, it won't happen. Go drive it, you'll see boost under load, and way before 6000 rpms...........

Jody

[GBodyGMachine]

Also, dont use octane booster. Do yourself a huge favor and put race gas in it if your afraid of detonation. And get someone with an A/F meter to check it out.
DONT beat on it until you get it tuned.

[DeltaT]

And lift if you hear any pinging or knock.

Jim

[Procharmo]

OK, all advice taken. Had MOT today. It was way to rich to pass the test. Leaned it out to 394 ppm co2 emmisions passed then turned all four mixture screws back in 1/4 turn. I have ordered 5 gallons of VP C16 race fuel. Damm that juice is expensive. I'm also waiting for an Areomotive A/F gauge and sensor from Jegs. Thanks again for all the info.

[Procharmo]

No racegas yet, but thanks for the advice. I have seen 7lbs at 3500 rpm at WOT. I have a problem applying WOT for more than a few sec's on the street in the UK. Too many corners, cameras, other cars, police and being able to glance at the boost gauge at the same time is not easy. I guess 15lbs+ at 6500rpm. This means I will have to install my MSD BTM before I rev any higher at WOT.

[Procharmo]

VP C23 120 octane race gas mixed with a small amount of 97Ron pump fuel. Saw 3000 rpm at 120 mph, couldn't glance at boost as I was in traffic, it was raining and I was on MT 315's with not very much tread left. 50 mph to 100 mph in less than 3 secs. I'll book in for a rollng road/dyno session now.

[GBodyGMachine]

Keep us up to date

[Y-TRY]

Dyno is a great idea. With that sort of power it's never safe to look down while on the road. Bring a jug of fuel to the dyno and go nuts.

Keep us informed.