The reason I asked is because the wagon pushes through the brakes at 5 inches of vacuum. I may need more brakes/converter, but if I could get the rpm up while staging by retarding the timing, then have it go back advanced when the brakes are released, it may help the boost come up a little faster. As it is now, I leave the line with no boost and it takes over 2 seconds to reach 9 psi. I also have a couple of .82 housings to try. It was just a thought! :idea2:
This is why I am using a trans brake with a 3 step rev limiter. This way I can leave the line at whatever RPM I want to and make lots of boost at the line.
Alan, I have the same problem. But if you use a startline rev limiter (2 or 3 strep) the engine doesn't make enough power to push you though the brakes. But the engine is still pumping air to move the turbines.
Alan, you need to isolate the brake booster from the intake under boost. Maybe an auxiliary vacuum canister plumbed into the brake booster line with some sort of one way valve at the intake. That may work. I'm thinking a one way valve may have a hard time because 5" of vacuum(as boost starts to build) would still bleed down the 15"(?) you would have without power braking(no boost). A solenoid that when activated blocks the line to the intake would do it 100%. Maybe a line lock because that closes when activated along witht he aux. canister. The GN's could build all kind of boost because they had the hydro brakes. A little more converter would help.
My car would push the locked up front tires right through the lights without the rev limiter.. It would build good boost on the line with the two step (5psi) and not move, but it would bog badly.. I never played with it enough to get it worked out.. Hope to have it back running soon..
Hello James, I was wondering what modifications you have made to the rotating assembly of your 455? I have been following your thread for a while, but I don't remember seeing much detail on this portion of your engine (sorry if I missed it somewhere). The main reason I am wondering is because I am considering a budget turbo-build for the 455 in my '71 Electra, but I'm only looking for 6-10 lbs of boost. I have read that you need larger end-gaps on your piston rings, and forged pistons in order to make a super/turbocharged engine last- has this been your experience? Thanks in advance- hopefully I didn't veer too far off course from your thread. -Matt
I do have forged piston and larger end gaps. However I have ran turbo's on stock engines as well. To put it bluntly, if you have detonation you will break your piston. A forged piston will last a little longer but will still fail under detonation. My suggestion to anyone looking into turbo charging. Invest in a good fuel system, A good AFR gauge, and a good electronic box that is boost referenced. And tune your timing and fuel curves properly before flogging the motor.