Jump to content
HybridZ

How about a throttle body BEFORE the turbocharger?! they did it but why?


Recommended Posts

Would love to know how that works but who can argue with the results:

 

"Qualification: maximum of 5.5 bar with Benetton cars: about 1300hp"

 

That's about 80# boost and .87hp PER cc and the Honda engine made a tad more hp. Thanks for posting that. The craftmanship is mind-boggling. It also reminded me of some of the brave men who drove those cars.

Link to comment
Share on other sites

As you can see from picture #1 the engine has individual TB's (note the linkage) you can see the orange cable going from the linkage, the same cable attached to the TB in front of the turbo in pic #2.

 

DSC06081.jpg

DSC06080.jpg

 

 

 

When the ITB's close, so does the one before the turbo, shutting off airflow to the turbo. With no more air coming in, the turbo spins in somewhat of a vacuum allowing it to sustain rpms (no air to slow it down). This is one form of anti-lag system (another being dumping fuel into the turbine on lift, WRC-style) used in different types of racing.

=)

Link to comment
Share on other sites

Vacuum allows the turbine to keep spinning....hey that's what I was guessing.

 

Is there any draw back to that system? If not then why don't all the turbo cars use this system instead of adding a BOV?

 

I would think the vacuum was cause the compressor to stall, wouldn't you be more likely to overspin the turbo in that condition?

 

/I'm violating the 'no technical thinking before 8am rule', bear with me :)

Link to comment
Share on other sites

Tony D mentioned that a turbo spinning in a vaccum has it's disadvantages

 

The reason for the throttling before the turbo is the SAME reason the CART people do it: they have a blowoff valve on the inlet manifold. If it lifts, you LOOSE POWER, and have a good chance that it will not reseat.

 

The throttling of the turbocharger inlet insures that the boost will NOT lift the pop vavle, allowing you to run the absolute maximum ammount of boost, without EVER chancing a boost-spike that would blow your valve.

 

I discussed this earlier with someone who wanted to argue about conterflow injection, and grinding sparkplug tips...

 

Anyway, the added advantages of running the turbo under a vacuum aren't that great, because you then have to use another seal to keep oil from getting sucked into the compression chamber---the main reason is to not lift the blowoff valve.

 

The CART engines use Barrel Throttles, BTW, not butterflies. There is no throttle shaft in the way to disrupt the airflow---this may be the same in the engine pictured, I haven't looked.

 

CG and simplicity of operation has nothing to do with it, it keeps pboost under the popoff level no matter what.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...