Thread: EFR BorgWarner Turbo

Originally Posted by Bush65

Originally Posted by isuzurover

John, do you have any info on suppliers or approximate prices?
(EDIT - have found some prices here: Turbocharger Search )

Which option do you think would be best as a single turbo for a 4BD1T - let's say I was after 250 flywheel Bhp maximum.

I have not looked for suppliers or prices.

Try BD Power as one possible.

My first guess (no calcs) for an EFR turbo and that HP would be EFR 6758. I think the next size up EFR 7064 would put you near 300WHP if you have the fuel.

Ben,
After a simple check it is obvious that the EFR 6758 turbo is too small for 250HP at normal rpm.

The approximate DR (density ratio of the charge air) required from a turbo to achieve a target power (250HP in this case) can be calculated if we know the power of the na (normally aspirated) engine (87HP for 4BD1) - assuming target and na power at same rpm (3200 for 4BD1).

Take required DR = (target power / na power) + 10%
For our example: DR = (250HP / 87HP) + 0.1
i.e. DR = 2.97

Now PR (pressure ratio) is greater than DR because the air is heated during compression (how much depends upon compressor efficiency! - read from compressor maps), and cooled by the inter cooler (how much depends upon inter cooler efficiency!).

For our first pass and using a look up table (for PR vs DR), guessing 75% for both compressor and inter cooler efficiencies (note these values may be optimistic), PR is approximately 3.4 - at 14.7 psi ambient this is approximately 35 boost pressure.

Now look at the map for the EFR 67mm compressor (page 114 of the linked document) and note PR of 3.4 is off the map (over maximum speed)! - it is always difficult to achieve acceptable efficiency at high boost pressure from a small compressor impeller (because boost pressure is a function of the tip speed squared).

So we can conclude that 250HP is not possible with this size compressor. Lowering target power to 200HP we get DR = 2.4 and PR = 2.7 (25 psi boost pressure at 14.7 psi ambient) - which looks comfortable (at this stage) for the EFR 67mm compressor.

Now look at the map for the EFR 70mm compressor (page 115 of the linked document) and note that the map is wide at PR = 3.4

So the EFR 67mm compressor could be a good candidate for 200HP and the 70mm could be good for 250+ HP.

This link is for the Excel spreadsheet I used for the above calcs. It was posted by the spreadsheet author in a tdiclub forum. Enter values into the green cells ('B36' to 'B41') for intercooler and turbocharger efficiencies, "desired HP" and "stock HP" (must be for na engine). Then read the value in the grey cell for DR ('B42')needed, then look down the appropriate column ('E' for non-intercooled, or 'D' for intercooled) in the cyan colour cells for the one with the DR value needed. When you have this cell, read across the row to the find the value for PR in the yellow cell - 'A' column. Now enter this value into the yellow cell ('B43') for "PR you need".

Before choosing a turbo you should input valid numbers into a good turbo calculator, such as the BW "Match-Bot", Squirel Performance, or not2fast turbo calculators.

Then plot points for the calculated PR vs corrected air mass flow, for various engine operating rpm's (e.g. for start of boost, maximum torque, power and engine speed), on several compressor maps to find the most suitable one - we want plotted points to be comfortably within the map area, particulary the surge line (left boundary), choke line (right boundary) and the choose a compressor where the points at .

Further more it is reasonable to use the value found for DR to estimate how much fuel is required, based on how much was required for the stock HP. In the case of the 4BD1 it works out as approx 160 cc / 1000 strokes for 250 HP (Edit2: 53.9cc/1000 st x 2.97 ~ 160cc/1000 st).

Edited to fix links and add more info.

Just started to play with the BW MatchBot program.

1st try with their small EFR turbo, 6258 EFR 250HP between 2500 & 3000 rpm, 300HP at 3500 rpm.

Edit: Click on the link on previous line to see my inputs and the results for 6258 EFR turbo - need some tuning yet. Next larger turbo 6758 EFR was off the comp map and 7064 has too large a turbine for spool-up.

Found this dyno chart on full-race site.

It compares results with EFR 6258 0.64 A/R turbo to Garrett GT2871R 0.64 A/R, both at 23psi boost - the EFR spooled much faster.

Originally Posted by Bush65

Found this dyno chart on full-race site.

It compares results with EFR 6258 0.64 A/R turbo to Garrett GT2871R 0.64 A/R, both at 23psi boost - the EFR spooled much faster.

That is quite a big difference.

Well lets give this a go then.

I just ordered a 6258 from Treadstone. Aiming to have it installed by Christmas... have to finish the firewall first.