Lean Burn 1991 Talon AWD Auto - Page 6 - Fuelly Forums

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Old 05-14-2012, 12:21 PM   #51
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Re: Lean Burn 1991 Talon AWD Auto

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Originally Posted by bazman View Post
Cool project! I like it a lot!

That BW turbo is massive for a 2L engine, as in huge - how many hp is it rated for?

I thought the smaller Evo turbo would be the primary feeding the larger BW as a secondary but you've stated it the other way around. How does that work - not sure I understand the theory?

Also what is the theory re your lean burn pre-chamber? I've not heard of that before and can't imagine how it works.

I do like the idea of pre-heating fuel for lean burn, but think a cold fuel by-pass would be required the instant load came on. Not sure though as when we tested hot fuel we had no ecu control to play with it and simply notice lost hp with the factory ecu settings. Ultra clean emissions though.
The BW turbo is rated at 1050HP

How the turbo compounding works is the small secondary turbo will spool first at its low flow lower rpm. This lets me run a tighter converter. When the small turbo reaches its max flow around 41lbs/min all that flow is sent to the larger 75mm turbo(about the same as a 351 CI N/A engine at 4500rpm). Around 35lbs/min the larger turbo will start to spool and then comes on line. Once the flow is over 41lbs/min the 28mm wastegate is choke and the first 44mm gate will open. Then once the engine starts flowing over 60lbs/min the second 44mm gate starts to open. Now the small turbo has still only 41lbs/min of exhaust going through its turbine and by-passing all the rest around it. The larger BW turbo has a 60mm wastegate and dumps to atm. to control its boost.

If you were to run it the other way the larger turbo would never spool due to a low N/A flow. Plus if it did spool the small turbo would be a restriction and make a ton of back pressure.

I built a modified combustion chamber for lean burn. It provides a fuel rich area around 14:1 A/F to help ignite the fuel and air,while the normal combustion chamber is at 20:1+ A/F.This prechamber provides a nice flame kernel that extends into the normal combustion chamber. This helps ignite the lean mixture and accelerates the flame speed during lean burn.
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Old 05-14-2012, 03:27 PM   #52
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Re: Lean Burn 1991 Talon AWD Auto

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Originally Posted by pgfpro View Post
The BW turbo is rated at 1050HP

How the turbo compounding works is the small secondary turbo will spool first at its low flow lower rpm. This lets me run a tighter converter. When the small turbo reaches its max flow around 41lbs/min all that flow is sent to the larger 75mm turbo(about the same as a 351 CI N/A engine at 4500rpm). Around 35lbs/min the larger turbo will start to spool and then comes on line. Once the flow is over 41lbs/min the 28mm wastegate is choke and the first 44mm gate will open. Then once the engine starts flowing over 60lbs/min the second 44mm gate starts to open. Now the small turbo has still only 41lbs/min of exhaust going through its turbine and by-passing all the rest around it. The larger BW turbo has a 60mm wastegate and dumps to atm. to control its boost.

If you were to run it the other way the larger turbo would never spool due to a low N/A flow. Plus if it did spool the small turbo would be a restriction and make a ton of back pressure.

I built a modified combustion chamber for lean burn. It provides a fuel rich area around 14:1 A/F to help ignite the fuel and air,while the normal combustion chamber is at 20:1+ A/F.This prechamber provides a nice flame kernel that extends into the normal combustion chamber. This helps ignite the lean mixture and accelerates the flame speed during lean burn.
Cool, yes that is what I thought just got confused by primary and secondary. Does the compound setup only add efficiency over a single turbo once boost levels get high due to increased parasitic loss at low boost?

Love the prechamber idea - clever. I wish you all the best with that.
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Old 05-14-2012, 07:49 PM   #53
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Re: Lean Burn 1991 Talon AWD Auto

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Originally Posted by bazman View Post
Cool, yes that is what I thought just got confused by primary and secondary. Does the compound setup only add efficiency over a single turbo once boost levels get high due to increased parasitic loss at low boost?

Love the prechamber idea - clever. I wish you all the best with that.
Its main advantage is it lets a small engine 2.5L or less retain its quick spool from the small turbo low rpm and large flow numbers from the large turbo at high rpm. It will also will have a much lower back pressure once the big turbo comes in.
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