pishta
I know I'm right....
So...how do you control boost? That's deadly! 
turbo: blow thru vs. draw thru
- Thread starter kittypancake
- Start date
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mrproffitt
Member
Boost is controlled by the A/R ratio of the turbine housing size and it has a small bypass hole the housing that can be adjusted. Also ignition timing has a part of it. Correct A/R housing (mine are 1.0), hole is plugged, timing under boost is 21 degrees. Starts making 5 psi boost at 3000 rpm and 10-15 at 5000. But I can’t hold on to the handlebars long enough to stay at rpm. Gears are 2.73 (C4 Corvette trans and transaxle) trike weighs 1250 pounds. Halfway through 3rd gear I’m hitting 150 and climbing fast. Never have maxed it out because I can’t hold on from the instant acceleration and pull from the torque.So...how do you control boost? That's deadly!
mrproffitt
Member
mrproffitt
Member
Inside the plenum. I added a “priority valve” by using some carbon fiber reed valves. This is so it does not bog down when you floor it. This was done by the factory many years later as the technology progressed in n the early 70’s.
mrproffitt
Member
This is a result of 24 psi and the wrong timing.
pishta
I know I'm right....
I wonder what the worlds fastest trike is? you should put a sissy bar on it and a headrest and go for it at Bonneville. When you get tired of it, put the motor and rear in a Manx buggy with some slicks!
mrproffitt
Member
I was originally building it for the salt flats when the SCTA informed me there is no “Trike” class and that any “motorcycle” class engine had to be built using 90% motorcycle parts. The Arizona Timing Association does have a run what you bring class with a $5000 prize for fastest time and $5000 for $5000 for top speed of the meet. I was calling it White Noise then for a cool salt racer name. Now it’s called Mental Illness. If you consider the Bloodhound SSC, it’s around 900 mph. But its a jet powered and rocket boosted sled sitting on three aluminum wheels.
oliver
Well-Known Member
Looks like too tight of ring gap. what gaps were you running? are those hypers? On boosted engines with hypers im running close to .030 end gap on top ring and .032 on 2nd.
mrproffitt
Member
Yes, as a matter of fact the pistons knocked all the ring lands off due to too tight of clearance on the factory ring gaps. That was a junk motor with 200k miles I used to experiment with and learned a lot from it. Now running .040” on top, .035” on 2nd ring on a rebuilt 5.3 with new factory rods, floating pistons, and ported heads. Timing at boost is now 19-21 degrees so there’s a better cushion to prevent detonation. If I run a water/meth injection, I can raise the timing and get more power, but it has plenty enough already.
This is my first trike I built with a 383 stroker making 450hp. DEI did the balance work on the engine and it was an amazing engine, all forged internals. Split the transmission in half twice on it spinning the engine hard! TCI replaced it both times, said they never seen it before other than mud bog trucks.
mrproffitt
Member
You know what’s really odd is the fact that it knocked the ring lands off 7 of the 8 pistons in the exact same place on the pistons, but the top ring gaps where in various positions and not where the chunks broke out. I think the #6 was the only one that didn’t. But all the others in the exact same position. Which happened to be where the high squish and largest squish area of the combustion chamber is.
Houseoffubar
Well-Known Member
All of this discussion aside, never EVER run a draw through turbo if there is any option to blow through!
Draw through has nothing but disadvantages.
Unequal fueling, you cannot run a blow off valve without sending raw flamable air fuel mixture somewhere.
The tubos because they must be sealed turn more slowly, the turbo slows dramatically and has huge loads imparted on it when the throttle is slammed shut, and you cannot intercool it.
On every level it is a horrible design!
That said, petty much every turbo vehicle that made my heart stop when I saw them, since the 60’s was some draw through machine
Draw through has nothing but disadvantages.
Unequal fueling, you cannot run a blow off valve without sending raw flamable air fuel mixture somewhere.
The tubos because they must be sealed turn more slowly, the turbo slows dramatically and has huge loads imparted on it when the throttle is slammed shut, and you cannot intercool it.
On every level it is a horrible design!
That said, petty much every turbo vehicle that made my heart stop when I saw them, since the 60’s was some draw through machine
pishta
I know I'm right....
One advantage comes to mind: Simplicity. No carb mods......except maybe going bigger. But you may as well hop up a flathead at that, technology marches on.
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