EBC's, ELEVATION AND TURBO SLEDS.... A GOOD TECHNICAL DISCUSSION.

Great thread fellas.

I couldn't believe it took so long for someone to mention the compressor maps. Our engines are so small and we run such low boost we're no where near the limit of the effincy range of these turbos (specifically the 2860 in the sidekick)

At a fist glance i have to disagree with the above statement about the torque curve feeling different at 5k ft vs 10k. I'm going to ponder that one for a while.

The air compressor example above is a great example for the differences in turbos - 7lbs on a 2860 may have a different mass flow rate than the efr

Btw the efr turbos are great. We ran one on our hillclimb car this season and it was impressive. MH - I signed up for Pikes Peak this year and may pick your brain as we're going to put on a bigger turbo as we're at the limits of our compressor Map at 2800ft elevation - we will be over working the turbo at 14k ft!

BOV reference lines need to be post TB to function.

http://www.turbosmartusa.com/technical-articles/flutter-compressor-surge/

"When your turbocharged engine is under load, the engine is consuming air (airflow) and your turbo is creating pressure (boost). These two things intersect on this graph and all is working as the turbo was designed for. Close the throttle however (as in when you would change gear or decelerate quickly), and the pressure maintains due to the momentum of the turbine wheel spinning incredibly fast, however the airflow has stopped because the throttle is closed. This situation forces the ‘intersection’ of pressure and airflow across the surge line as the pressure momentarily peaks and airflow virtually stops, forcing the turbocharger into compressor surge."

"This is where a blow-off valve comes into its own. They are fitted between the turbocharger and the throttle body. The closer to the throttle body, the better, as it will increase the response to mitigate surge.

The purpose of the blow-off valve is to eliminate compressor surge. To do this, its job is to open as quickly as it can when there are rapid changes in engine load from boost to vacuum – such as a throttle plate closing. The open valve ensures the air flow continues in the charge pipe, eliminating the pressure spike and (referring the graph above again) ensuring that the turbo can continue in the ‘zone’ without tripping over the surge line."

Here's a nice easy to understand article explaining the merits of an EBC setup on snowmobiles from the VOHK tuning guys.

#whyboostcontrol #stopthebs

mountainhorse said:

.... and bleeds red, white & Boondocker !!

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This. Obviously, BD makes some great stuff. But there are a number of systems out there that work great.

mountainhorse said:

Exactly... and, for me... They all have a feature that I'd like to incorporate into a single low boost system.

I really like the simplicity and, especially, the low spool-mass of the EFR turbo, An EABC, Tunnel dump exhaust, good aerodynamics for the charge tract, a quiet stainless muffler, pre-programmed ECU, Factory location cold air intake with increased area, well calibrated clutch kit, Adjustable CRV, no intercooler, no oil tank, no gauges... and a reasonable price for this simple system.


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Its as if you have a crystal ball

mountainhorse said:

And by low boost... I'm talking about 18.5 - 20.5 PSIa... that stays consistent and fully pump-gas-91 compatible at all elevations.




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I'd say anything above 18 and we're past pump gas territory, depending on how much timing is being pulled, how good you are at finding "good" non eth 91, how often you do 1 minute WOT pulls and if there is an intercooler or not.

But I could be wrong...