Adjusting Boost

[smithk3933]

Newbie to turbo systems question:

What is the mechanism used in the various turbo add-on systems to adjust boost pressure and hence the power output? I see a lot of discussion around the various power ranges for a turbo system and assume that boost is the main determining factor. Is this done electronically or mechanically to blow off excess pressure.

Thanks for the education.

 

[doc_tai]

it calls boost controller, it controlls wastegate when to open to relieve pressure. Only can add more boost not subtract . Let say you have 3 psi spring in you wastegate that's your lowest boost you can go

 

[Cody@LoveFab]

The AEM EMS has a built-in boost controlling function that surpasses anything else for the price range. This is why I recommend using the AEM EMS whenever possible(91-94 NSX's).

With the AEM EMS, it's possible to dial in boost levels based on vehicle speed. In other words, you can dial in say 5psi in 1st geat, 10psi in 2nd gear, 15psi in third.

To further answer you question, boost levels roughly equate to HP levels. With the examples I gave above, and with our turbo system, you would have ~360WHP, ~480WHP, and ~550WHP.

What does this mean? That your car actually accelerates instead of turning the tires into smoke in the lower gears. :biggrin:

 

[smithk3933]

So I see that a number of the turbo kits use the TIAL 44mm wastegate. If I understand the wastegate allows someway to bleed off exhaust pressure and reduce the speed of the turbo and thus the boost on the charge side. Any more details on the boost control function and how it operates in conjunction with the WG? Is there a sensor that feeds the controller and then an electrical solenoid or pressure based release in the WG? Is the exhaust that is bypassed then fed back into the exhaust downstream of the turbo.

Just trying to make sure I understand the general concepts/layout. Any good reference articles that come to mind?

Are NA1 or NA2 any easier to modify? How about the gearing in the NA1, does a boosted engine help with the flat 2nd gear area? My NA1 had the short gears installed previously.

Thanks.

Keith

 

[Cody@LoveFab]

There are a lot of broad questions here, but yes you have the concept about the wastegate system correct.


There are several styles of boost control but the electronic style is what we prefer for adjustability, etc. The MAP sensor reads boost levels and there is an electronic solenoid that directs pressurized air from the turbo to the top of the wastegate, effectively closing the wastegate for a longer period of time, which raises boost levels.

I prefer NA1's(91-94) because of the ability to use the AEM EMS. The NA2's are generally nicer cars to start with, but it's not possible to use the AEM EMS with the NA2 cars as intended.

The NA1 transmission isn't too bad with a properly sized turbocharger. You can certainly install short gears but I would NOT install a shorter final drive(specifically avoid the Comptech 4.55). When mine failed, it luckily only destroyed the transmission. Other failures have taken out the engine as well.

I advise anyone who has the 4.55 final drive installed to remove it if you are shooting for anything much over 350WHP.