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Yale

Traded Turbos with another owner

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(edited)

Wow, was there a difference. We had both done things to our cars but still we were both struck but how two exactly the same cars drove so differently.

 

My car has the Ireland Engineering handling package, I just love this, makes the car tight and more fun on the twisty's for me. I was chasing a friend in an Alpine Renault for a few hundred miles one day when it became apparent to me I needed to do something :)  

 

His car had a custom short shift and a clutch from a later model.

 

Funnily enough he was happy with his suspension as it was and I was happy with how my stock four speed trans shifted!

 

Now what was different was how the turbos came on, mine took quite a while steadily building boost and speed, a giant hand so to speak getting a round to shove you along, as you feathered the turbo in and out of the green on the gauge. His was in a way a more violent reaction, with the turbo gauge needle going through the green part in the blink of an eye.

 

Neither of us could figure out why there was such a difference. I don't know about his KKK by the way, but mine is a NOS one I got in Germany a while ago. That said, it is similar to how my car drove with the older more loose turbo I replaced with this one. I will say before, there was an amazing whistling as my my loose turbo spooled up that is no longer there.

 

His car had wisps of white smoke under boost I should add.

 

It was a lot of fun.

 

 

 

 

 

 

 

 

 

 

 

 

two turbos small.jpg

Edited by Yale
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I would love to be passed on a winding two-lane road by a pair of factory turbos, with their turbo’s In the green zone!

 

Great fun!

 

Who’s got the Webasto roof? U.K. car originally?

 

Regards,

 

Steve

 

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Hey Steve, Yes the other guys Turbo had spent time in the UK where it probably got that sunroof. He bought it in Switzerland.

 

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It would be so much fun to get a bunch of them together and everyone have a drive in each other's cars.  Most of us only know what ours feel like and don't really have anything to compare them to.  I have driven 7 different turbos and each one was a unique experience.  Some were modified (even slightly) others were old and tired, and a couple were as carefully restored as possible but even they were different.   

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Amazing Pre, that isn't what I would have expected. The few that are out here I think people mainly take to shows. I don't think they just drive around in them like I am. Thanks for weighing in here.

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It's great that you were both able to drive so many Turbos and compare.

 

I have only driven three others than mine decades ago, and found them lackluster, even compared to a Tii. I was asked to tune each of them as the owners took them to shops unfamiliar with the setup and they mucked up the works. Add in distributors so out of whack......well, you get the idea. In each case i was able to "field tune" the car to at least ameliorate some of the performance issues, as the owners didn't want to spend the coin nor time to have the distributor, pump and altitude compensator calibrated. In the end, they were satisfied; but me, meh.

 

As Byron said, differences seem to gravitate toward the condition of the engine, injection system and the tune.....and of course the gas used. 

 

It is sad to see cars that are not running up to their potential, because the owners are missing out on some big grins of performance.

 

 

 

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On 8/5/2019 at 4:23 PM, Yale said:

what was different was how the turbos came on, mine took quite a while steadily building boost and speed, a giant hand so to speak getting a round to shove you along, as you feathered the turbo in and out of the green on the gauge. His was in a way a more violent reaction, with the turbo gauge needle going through the green part in the blink of an eye.

 

Neither of us could figure out why there was such a difference.

 

I was thinking about this and with the assumption that all other engine specifications and wear being equal, figured that if the maps of the turbos were the same then it might be the overpressure valve's action.

 

It is not just a flat disc held in by a spring, which by the way is much stiffer than 8#, the purported boost limit. In taking it apart, but not all the way, there is, I believe a reversionary circuit with a floating piston moved by the action of pressurized air through little holes in the casting.

 

I would love to have a diagram of this and I have not yet tested the unit while on the "arm" casting by enclosing the ends and pressurizing to see how that works.

 

Regardless, perhaps there is sticking in the action of that disc (closed / open) or plugged passages which account for the more "violent" reaction as opposed to a smoother reaction (measured pressure relief) when coming under boost.

 

The other thing would be to check the big nut on the back of the injection pump. In taking it off, if there is a pool of oil leaking out, you have a seal problem. If the rear injection pump seals fail it allows oil to pass into the barometric cell / pressure regulator. Given enough leakage it will restrict smooth movement and / or hydrolock causing and on/off situation. In addition, leakage can allow oil vapor to go through the little hole in the piston to the vacuum booster line and be burned under boost, causing the white smoke that you observed. Check for oil fouling on the plugs.

 

HTH

 

Ted

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