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Discussion Starter #1
Turbo charged engine rpm almost flatlines. After launch engine rapidly reaches around 7350=7550 then just sits there through 1st and actually decreases a bit half way through 2nd gear. Rpm loss on shift to second gear is hard to see but less than 100. Engine will free rev to 9000 rpm no problem. Valve springs are fine. Engine doesn't miss or break up and is not on any kind of electronic rev limiter. Car pulls fine and runs 7.7s. I called converter maker and they're baffled.


3000# mustang.
400 SBF with twin 80mm turbo's
Glide with 3.73 rear gears
9.5 PTC converter 15-0 stator
Camshaft has 750 lift and 267 degrees [email protected]


 

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Discussion Starter #3
Newly rebuilt PG with band adjusted and fluid changed after 6 runs.......no change.
 

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yeah with a turbo engine you typically want 1300-1500 fall back on the shift with a glide, sometimes a bit less sometimes a bit more depends on the car, that certainly looks like a converter up at its TQ limit, is it beating on the limiter the whole way down the track ?
 

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Discussion Starter #5
yeah with a turbo engine you typically want 1300-1500 fall back on the shift with a glide, sometimes a bit less sometimes a bit more depends on the car, that certainly looks like a converter up at its TQ limit, is it beating on the limiter the whole way down the track ?
The only limiter set is the rev limit which is set at 9000 RPM. Engine simply won't get past mid 7000 RPM range. Car accelerates nicely during run while riding that mid 7000 RPM range it just won't rev higher. Engine is not touching any limiters during the run. Also, trans fluid doesn't get very hot during bump box use or run....160 degrees max is all I see.
 

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Where do you want to shift the motor at?
 

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Target boost at 26.. Actual boost after 1.5+/- sec into run, and 7500rpm, is only 20.2#. Loss of engine load, due to driving thru the converter?
 

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Discussion Starter #11
Target boost at 26.. Actual boost after 1.5+/- sec into run, and 7500rpm, is only 20.2#. Loss of engine load, due to driving thru the converter?
Using Holley Dominator EFI for boost control. Target boost of 26 is Dome pressure with actual engine at 20.2 LBS. Plus, big air/water intercooler has a small amount of loss not to mention a bit of exhaust back pressure results in Dome pressure and engine boost never being the same. However, driving through the converter seems likely.:)
 

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Turbo charged engine rpm almost flatlines. After launch engine rapidly reaches around 7350=7550 then just sits there through 1st and actually decreases a bit half way through 2nd gear. Rpm loss on shift to second gear is hard to see but less than 100. Engine will free rev to 9000 rpm no problem. Valve springs are fine. Engine doesn't miss or break up and is not on any kind of electronic rev limiter. Car pulls fine and runs 7.7s. I called converter maker and they're baffled.


3000# mustang.
400 SBF with twin 80mm turbo's
Glide with 3.73 rear gears
9.5 PTC converter 15-0 stator
Camshaft has 750 lift and 267 degrees [email protected]


What fuel are you running ? and what's the timing set at for 7500 rpm
 

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Using Holley Dominator EFI for boost control. Target boost of 26 is Dome pressure with actual engine at 20.2 LBS. Plus, big air/water intercooler has a small amount of loss not to mention a bit of exhaust back pressure results in Dome pressure and engine boost never being the same. However, driving through the converter seems likely.:)
Where does the gate spring psi enter in this?
I didn't understand Sam's comment on the dome and boost being the same.
 

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The converter needs to be tighter or use a thicker fluid. If the motor is hanging at 7500 rpm, this is your flash point at the current power level. To shift at 8200 I'd say you need to go 400-600 rpm tighter. This will allow room to turn the boost up. The engine will get to 8200 now but you will have to turn the boost up. You don't have enough power to get the engine passed the coupling point of the converter.
 

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Discussion Starter #20
The converter needs to be tighter or use a thicker fluid. If the motor is hanging at 7500 rpm, this is your flash point at the current power level. To shift at 8200 I'd say you need to go 400-600 rpm tighter. This will allow room to turn the boost up. The engine will get to 8200 now but you will have to turn the boost up. You don't have enough power to get the engine passed the coupling point of the converter.
Outstanding info. Next time out I will turn the boost up and see what happens but I will still have to get the present converter tightened. Is that just a stator change to my current PTC 9.5 15-0 converter?:)
 
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