MATH+Logic: An engineering approach in search for a perfect TURBO. (1 Viewer)

Joined
Jun 10, 2007
Messages
5,424
Location
Kiwiland
Dougal, Great info! This definitely helps me understand Turbine A/Rs and matching a bit better. One thing I cant figure out is how to convert Phi value on the BW maps to LBS/min that is on say a Garret map. So could you share how you achieved the 20lb/min from that graph? Just looking I obviously see .028 so is it technically 20.8 lbs/min or am I off?

It's also interesting what you point about CCF and turbos performing hot or cold based off design and efficiency. Just yesterday I was browsing a 90 page forum over on patrol4x4. Dudes over there doing some interesting stuff with the Patrols and EFR 6758 and 7163

Quote from OldMav "I just changed the turbo and a few adjustments to the gate to stop it humping, on my sons 2004 T ute. On the 6758 it was set to 204rwkw and 785Nm same fuel no changes it did 217rwkw and 815Nm. but all 100 to 150 rpm later. Driving it i couldn't tell the difference even off idle spool and driveability. It didn't blow off the recirc valve or i didn't notice it still made a racket from the snorkel which is normal from a efr. I have my doubts if it would work on less fuel but for this power tune its pretty good and would be a lot better than this had i played with pump tune. i am positive i could get it to spool the same as a 6758.with more early torque. AFR on the 6758 is at 16 to 17 highest and never see 650C pre turbo. The 7163 picked up the afr's to 17 to 18.5 highest. I would chuck a bit of smoke off idle with 14 to 15 to get 6758 off idle spool. Also emp:imp was all lower than 1.1:1 btw and egt was never above 600C after each dyno run pre turbo."

One thing interesting about the EFR is the lower inertia shaft as a product of the light Ti-Gamma turbine wheel. This paired with BW very well designed exhaust housing and efficient internal wastegate abilities it creates a more sophisticated way to tune this turbo. It's observed in these turbos that backpressure and EGT are lower down compared to say... a Garret equivalent. So not being able to drive the turbo with what's typically done by driving a turbine with EGT and backpressure being higher they had to come up with a way to drive the turbo to get the response they wanted in lower RPM cooler EGT areas with an electronic boost controller, specifically the Eboost street 2 from turbo smart. From what I could gather they use this controller to absolutely make sure the wastegate doesn't crack open for any reason other than the controller telling it to at a specific boost pressure which I believe for them was right at 24psi, Target boost was 28-30psi and they also had a 30psi wastegate can on the turbo making sure that the wastegate doesn't crack open with backpressure too early. This created a scenario where backpressure was reaching 1:1 right around 28psi on the gauge the wastegate would now swing open to control boost at a very specific moment that EMP was at a great drive ratio and EGT high enough to continue driving the turbo.

I may have butchered this a bit but the idea here I think is because of the efficient turbo and having a higher CCF they have to drive the turbo by making sure the gate doesn't open until a very specific moment 3-5psi before the target boost to get the turbo to respond very fast without sufficient EGT. With a manual controller set to 28 psi with the medium wastegate can that BW comes with it was causing the turbo to get near peak boost but then EMP was pushing the wastegate open early and the turbo would momentarily drop boost before rising again. My logic may be off a bit but this is currently how I interpret it.

Another interesting quote from OldMav explaining it

"The standard actuator high boost is a quality actuator but like all cans it is a compromise. The 30 psi can is full open at 30 psi and it cracks at about 16 to 18 psi as i remember (would need to check again). Ideally on a 11mm IP we don't want the actuator opening before 22 to 25 psi then we want the actuator controlling EMP from then on. In the real world we just don't have boost only or IMP holding the waste gate flap closed we also have exhaust pressure acting on the flap from the other side pushing it open. From Maths we can calculate that there is 1:1 emp:imp ratio at 2000 rpm (yet to be confirmed) at full fuel from a adjusted std 11mm at 28 psi with zero waste gate movement. So we have 28psi acting on the actuator from both directions. Ideally we want the actuator to only open from here on to control boost pressure but also to hold EMP at 28 psi also for an ideal 1:1 emp:imp ratio. A manual controller and single can has no reference to EMP or what the can is doing, all it can do is move the crack open point further up the boost graph. For our 30 psi can and with pre load we can set boost for 28 psi but what we are doing is setting a equilibrium between boost and exhaust pressure. So it will crack open about 20psi to maintain a 28psi pressure. But will not have the boost pressure to move the waste gate flap further than a few mm or about 10 degrees of flap of the 50 degrees possible needed for full gate open position. Thinking this logic i am sure you can see the problems with slap together can gate systems with manual controllers restricting full gate open condition on a gate hole too small for the engine to start with.

What happens here is we loose boost and we see boost drop off because the manual actuator has no control over EMP. So EMP builds up due to the can has run out boost control movement ability loosing lbs/min pumped but not necessarily Boost psi. This effect sees torque and Kw's drop off dramatically after 2000rpm which is very common to see on dyno runs. The electronic controller set up as normal has no direct control over EMP either but has the ability to hold 28psi then it has the ability to move the dual port actuator to full open if need be to control EMP and still keep 28 psi desired boost pressure from 2000 rpm onward. This effect has the ability to move the PR point across the compressor graph because we don't have a too high an EMP acting on the wheel loosing turbo shaft speed. Hence we get more Lbs/min pumped which equals torque holding ability, by product is Kw's."

Phi and lb/min CCF are exactly the same thing just using different units and reference temperatures. You can convert one to the other. I had the exact conversion figure somewhere but if you divide 20 by 0.028 you'll be pretty close.

That dude is way overthinking wastegates. It's really simple. If it blows open earlier than you want (due to EMP) then you get a bigger can and a stiffer spring. This setup will open at the same signal pressure but be a lot more disciplined regarding EMP so it won't leak early. Several guys in the USA were selling oversize actuators for controlling high boost on diesels. I have yet to see a dual port actuator where the second port was even sealed!

Another DIY solution is to add addtional external springs to help hold it shut. Pick your spring and preload to solve your problem.

Torque and power are going to drop off over 2000rpm anyway. At that point your engines V.E. is dropping and your pistons start to out-run your burning diesel. There's only so much advancing injection can do.
That's why diesels have a most efficient operating point (and peak torque) at lower rpm. It's nothing to do with boost.
 
Joined
Jan 23, 2018
Messages
150
Location
San Diego, CA
Phi and lb/min CCF are exactly the same thing just using different units and reference temperatures. You can convert one to the other. I had the exact conversion figure somewhere but if you divide 20 by 0.028 you'll be pretty close.

That dude is way overthinking wastegates. It's really simple. If it blows open earlier than you want (due to EMP) then you get a bigger can and a stiffer spring. This setup will open at the same signal pressure but be a lot more disciplined regarding EMP so it won't leak early. Several guys in the USA were selling oversize actuators for controlling high boost on diesels. I have yet to see a dual port actuator where the second port was even sealed!

Another DIY solution is to add addtional external springs to help hold it shut. Pick your spring and preload to solve your problem.

Torque and power are going to drop off over 2000rpm anyway. At that point your engines V.E. is dropping and your pistons start to out-run your burning diesel. There's only so much advancing injection can do.
That's why diesels have a most efficient operating point (and peak torque) at lower rpm. It's nothing to do with boost.
Thanks for the info, Dougal. I am still on my quest to find a single turbo sized as best I can logically to hopefully achieve a power level with a response that I will be happy with. For the longest time, I continually try and make turbos work that are probably too large for my goal, and I'm finally getting to a point where I feel I am getting into a good ballpark. I have come across the newer Garret G25-550. The compressor map seems to match quite well and I have mapped it at 20 psi and 25psi at three points 2000rpm - 3000rpm - 3500rpm. I also multiplied my mass airflow of 43lbs/min at 3500rpm for 25psi and 38lbs/min at 3500rpm for 20psi by .20 to get an idea of surge margin so around 7-8lbs/min and a PR of 1. You will see this in the graph. If you arent familiar with the G25-550 it's a 48/60 Inducer/Exducer compressor and 54/49 Ind/Exd turbine with A/R options of .49, .70, .72, and .92 A/R. The .49 A/R lies right on the 15lbs/min gas flow for the turbine map which would probably be the go for turbo response. I would run this with a custom log manifold and external wastegate for better EMP and boost control as well as having the option of easily swapping A/R housings if need be.

Please let me know your thoughts and maybe your opinion on a better Garrett option.

Comp-Map-G25-550.jpeg


Turbine-Flow-G25-.jpg
 

IanB

SILVER Star
Joined
Jan 23, 2010
Messages
4,381
Location
Winnipeg, MB
That dude is way overthinking wastegates. It's really simple. If it blows open earlier than you want (due to EMP) then you get a bigger can and a stiffer spring. This setup will open at the same signal pressure but be a lot more disciplined regarding EMP so it won't leak early. Several guys in the USA were selling oversize actuators for controlling high boost on diesels. I have yet to see a dual port actuator where the second port was even sealed!

Any chance you or anyone else know of a source for a more robust wastegate actuator for a ct26 application (Gturbo)?
 
Joined
Jan 23, 2018
Messages
150
Location
San Diego, CA
Any chance you or anyone else know of a source for a more robust wastegate actuator for a ct26 application (Gturbo)?
I actually just order a turbosmart IWG75 dual port actuator and the e boost street 3 port controller for my grunter. I may have to figure out a mounting solution but it will work. I’m going to be port patching my manifold, turbo, and wastegate when I put this on in hopes to control boost and EGT better

EDIT: I’m doing this while I wait for an alternate solution for a turbo. The EFR6758 seems to be my most viable option for what I’m wanting at the moment. The Garret G25 while I think it’s compressor is a great match, I’m afraid it will be too choked up on the hotside with its tiny turbine wheel.
 
Last edited:
Joined
Jan 23, 2018
Messages
150
Location
San Diego, CA
So after a lot of pondering and stress, I decided to take the leap on an EFR7163 .80 A/R twin-scroll Borg Warner turbo. In about two weeks ill be sending it to my Fab shop to build a custom-divided manifold and after ill be installing an electronic boost controller and 2 port wastegate actuator to be able to control boost more precisely. This may end up being on the more "laggy" side as many others would probably say but I plan to free up my higher RPM power by decreasing the high drive pressure created by the small turbine side of the Grunter Extreme. I especially want a more broad powerband and the grunter just seems to fall off way too hard at 2600rpm and I really want to rev out to 3000-3500 even 4000rpm and still make great power. I could have gone with some of the more tried and true CT26 variants with larger turbine sides but it seems most if not nearly all data I could see from these options still had undesirable EMP:IMP. If my logic is correct this turbo is going to have me no higher than 1.4:1 EMP:IMP. I will be doing this on standard pump and injectors but if for whatever reason I can't give this turbo enough heat and fuel I plan to sort the fueling after but I hope that won't be an issue. I will report back after it's in and I have some good data and feedback. :cheers:

IMG_4135.jpg
IMG_4136.jpg
IMG_4137.jpg
 
Joined
Jun 10, 2007
Messages
5,424
Location
Kiwiland
That's a big turbo but an efficient turbo. What is your low-end response going to be like?
One big decider for what size turbo is too big is altitude. If you're primarily at sea-level (cough*australia*cough) then you can run bigger than those in Colorado.

The ultimate killer of high rpm power in diesels is the burn speed of diesel. It can't keep up with the pistons so combustion pressure drops and you can only advance timing so much to keep up with it. That's why they all have a cutoff and longer stroke diesels have a lower rpm cutoff.
 
Joined
Mar 11, 2019
Messages
407
Location
80 Series 1HD-FT
I personally know guys with 1HDFT's and 1HZ's revving out to 6000rpm, I'm currently getting 5000rpm myself in my FT and still aiming for higher with more mods to come! I'm sure the DT and FTE would be no different but I don't know many people with these. Fueling and timing control isn't really that difficult to modify to work but the ultimate killer of high RPM power is actually EMP from less than ideal turbo choices
 

AussieHJCruza

SILVER Star
Joined
Jul 8, 2013
Messages
1,851
Location
New South Wales, Australia
I'll bow out of this discussion, we're obviously on a totally different wavelength @KiwiDingo - yes, 7k for a petrol isn't particularly revolutionary and also irrelevant to this thread, what I'm trying to say is, I see no value in spinning a 1HD (or most other diesels) to 5k plus from an efficiency or longevity perspective. You clearly think otherwise so that's fine
 
Joined
Jan 23, 2018
Messages
150
Location
San Diego, CA
Dougal, I am concerned about response as well. This was a huge risk for me but after playing with match bot for nearly 6 months and reading about the patrol boys having great results with the EFR 6758 and 7163 I decided to take the plunge on the 7163. Because this turbo is going to be flowing so well I'm getting the manifold made out of thick schedule 40 mild steel, ill be ceramic coating the inside and outside of the manifold, maybe even a manifold blanket, I will also run a turbo blanket and heat wrap the downpipe all in an attempt to keep the heat in the manifold as best as possible. I personally don't care to spin the engine to 4000rpm often but I will definitely be looking to make most of my power in the 2250-3500rpm range which I think is reasonable. I have already discovered my head gasket is too thick, I'm running a notch 5 when I should be a notch 1 as per the FSM. After learning a lot about squish and swirl I wonder now why so many people jump straight to notch 5 regardless of their piston protrusion. This could also contribute to better low-end performance once sorted. I'll check back in once I get the turbo in and tuned enough to get some results.
 

Indestructible 47

SILVER Star
Joined
Jun 23, 2014
Messages
1,187
Location
Straya
Dougal, I am concerned about response as well. This was a huge risk for me but after playing with match bot for nearly 6 months and reading about the patrol boys having great results with the EFR 6758 and 7163 I decided to take the plunge on the 7163. Because this turbo is going to be flowing so well I'm getting the manifold made out of thick schedule 40 mild steel, ill be ceramic coating the inside and outside of the manifold, maybe even a manifold blanket, I will also run a turbo blanket and heat wrap the downpipe all in an attempt to keep the heat in the manifold as best as possible. I personally don't care to spin the engine to 4000rpm often but I will definitely be looking to make most of my power in the 2250-3500rpm range which I think is reasonable. I have already discovered my head gasket is too thick, I'm running a notch 5 when I should be a notch 1 as per the FSM. After learning a lot about squish and swirl I wonder now why so many people jump straight to notch 5 regardless of their piston protrusion. This could also contribute to better low-end performance once sorted. I'll check back in once I get the turbo in and tuned enough to get some results.
Keen to see how this works out for you. The patrol guys all seem to like the bigger turbo, but the patrol engine is indirect injection. Anyway, it's an efficient turbo and should be good quality so that's working in your favour.
 

Users who are viewing this thread

Top Bottom