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@griff Where did you source the LFX to DCT adapter parts? Are those one-off you machined or an off-the-shelf kit?
unfortunately at this time they are all one-off parts. More to come on that front though once I get this damn thing working. I planned to get some solid progress made last week but ended up fighting off a 105 fever for a few days. Almost back to normal today but still ZERO energy.
How's your progress been going on your ECUmasters setup controlling the DCT?
MUCH progress lately! I have the car running fully on the Syvecs ECU with the GDI delete and GT3RS throttle body. Purrs like a kitten on 1300cc injectors! DCT is in a VERY basic configuration and I am actively working through all of the CAN messaging. Should go pretty quick once I have all of the elements identified and what devices need them but the planning phase takes a fair bit of time because not all CAN devices are created equally. Once that is done I will develop all of theTraction Control and calibration strategies I want in the car. Last step will be time on a steady state dyno to see what kind of boost she can take with PFI and lower compression.
She is now fully functional with a BMW DCT and converted to port injection on the Syvecs. This weekend I will start fabbing up a new hood to clear the intake.
Hope this build has continued on, it's been fun to see the progress. A few years ago I put one of these LFX engines into my E36 BMW, leaning pretty heavily on Keisler's parts and the knowledge shared by you and others who have put these in Miatas and RX's. I completed it in 2021, and since then, i've seen a couple others put them in BMWs (mainly older ones), FRS's, kit cars, and the like.
It's now time for me to switch to port injection and add a turbo.
I have a lot of questions for you:
1. was that turbo the right choice? How did you decide on the AR for the exhaust side? For my setup I'd like to stick with a T4 inlet, which may limit me to AR around .7 or above 1.
2. are you now using LF3 rods?
3. and are you using LF3 pistons? can you tell us to what specification you had these machined, and did you do this yourself or take them to a machinist? It'd be nice to know of an off the shelf alternative that would get compression to below 10, while no longer having the pattern in the piston top for DI that is no longer needed, but i just dont know of any. i wonder how that piston top shape effects performance now that the engine uses port injection?
4. if you can share, i would love to know the numbers you were able to achieve once you went to the dyno. I see you went with the CNG fuel rail, it's a shame it's so expensive. but it's really the best/only option outside of fabricating something yourself. did you have to make any modifications to the rail? i.e. is the fuel system still dead ended, or did you add a return?
It brings me a ton of joy to hear this thread has helped you as it has many others! The car has come a long way and I finally was able to find a stable spot in the build so I have been driving her rather that staring at it up on a lift. Currently it is fully functional on port injection, BMW DCT, rear mount turbo with boost controlled via electronic wastegate. Due to the DCT I decided to run her on a MaxxECU. Not my first choice, but their direct control of the DCT was a pleasure after all of the nightmares from the HTG GCU piece of garbage.
These days most of my money and time is going into building my dream shop. I know once I have that done I will enjoy my time in the shop SOOO much more so it has taken priority.
As for your questions.... 1. was that turbo the right choice? How did you decide on the AR for the exhaust side? For my setup I'd like to stick with a T4 inlet, which may limit me to AR around .7 or above 1.
Turbo location and final compression ratio will dictate this more than anything as I'm sure you know already. Post up some specs and plans and I will help best I can based on all I have learned over the years. I No matter what you go with a EMAP sensor is the key to proper setup.
2/3. are you now using LF3 rods?
This was a bit of an evolution for me. I scored some LF4 Ti rods and got a set of LF4 pistons. You can sometimes find Ti rods CHEAP out of Mexico and they are indeed the real deal. I highly recommend them too if you already plan to tear into the bottom end. Just know that if you go that way you will need to change the pistons and heads to the LF3/4 components as well due to rod length and valve angle differences. I started to go this route but when I found that the LFX heads would not work I decided to just machine my LFX pistons. You can buy LF4 heads and I was able to verify that for the 2k you will spend, they will come ready to bolt on with sodium filled valves which is really nice. I am a mad man/idiot and ended up just machining my own pistons on my little Grizzly mill. LOL I mainly did that because I am cheap and like to learn. My opinion is that the HFV6 GM developed (LFX, LF3/4) bottom end is capable of substantial power, and capable of 1000hp pretty reliably. With a stock LFX bottom end you are going to tap out at about 450hp and you will be knock limited to about 10psi on e85. Your duty cycle on the GDI system at that point will be maxed out, but just going to PFI will not help much since the comp ratio will stop you at the same point and dropping that comp is the only real solution to more power. I honestly dont think the piston face design has too much of an impact on max output when you convert to PFI as it is mainly for fuel economy with GDI at lower RPM levels and actually will reduce potential at higher RPMs....or so I was told by several top level tuners I know and respect that have real world dyno comparisons as proof. The amount of material I removed was purely based on final piston face thickness and volume to hit my target comp ratio. I think as a rough guide, there is a dimple on the LFX piston faces. If you machine them down 2 thou below that dimple you will end up with a 9.9:1 ratio with LFX heads and plenty of material on the faces. At that comp ratio I have still not hit the knock threshold on 93 octane and 22psi of boost!
4. if you can share, i would love to know the numbers you were able to achieve once you went to the dyno. I see you went with the CNG fuel rail, it's a shame it's so expensive. but it's really the best/only option outside of fabricating something yourself. did you have to make any modifications to the rail? i.e. is the fuel system still dead ended, or did you add a return?
So I have not actually put the car on a roller to see where it ended up but I am confident she is over 600 at the wheels with a solid safety margin in my ignition mapping. I honestly didn't care what the HP numbers and I life out in the sticks with no dynos anywhere close to me so it was never a priority. I moved my attention over to power/weight and busted out the cutting wheel and carbon fiber supplies and took her to Jenny Craig. Every panel is now carbon or carbon/kevlar and with all the work I have done she scales out at 2047 lbs track ready with a 1/2 tank and 200lbs in the driver seat. Balance is pretty damn good too! If you have never driven a 2000lb caged miata chassis with 600+ at the wheels, I HIIIIIGLHY recommend it!!!! The CNG rail is a returnless but works fine. My fuel system is an e85 capable miata pump to a DW surge tank with a pressure regulated DW pressure regulator. Injectors are ID 1300s
thanks for the info. And just to be clear, you are using LF4 rods with machined LFX pistons and LFX heads.
the LF4 rods are I think about 1.5mm shorter than LFX rods, did you take that into consideration when determining comp ratio? And what head gasket did you end up using? I think the LF3 or LF4 head gasket is multi layer steel? The steel gasket has got to be thicker than the LFX gasket right?
And I agree with you regarding the capability of these engines. I compared all the high tech modern V6 engines, and the reality is that they are all pretty damn good (Ford, GM, Toyota, Nissan, Honda) - and I've taken apart all of them. But in my opinion, GM's gets top marks for many aspects: alloys used, strength engineered into nearly every casting, build and machining quality, availability, packaging. The Japanese seem to do just a tad better in terms of specific output, but it is negligible given the strength that GM engineered into the high stress components. So many people thought I was crazy to put one of these into a BMW track car but the reality is that for the cost of one BMW engine I can get three rebuilt LFXs at the same power level, with more torque, less weight, and better reliability (yes, really). Some people just can't believe me when I tell them there is no "timing chain" issue.
I was able to find the seller on ebay offering the titanium LF4 rods, so I picked up two sets. these things are incredible - a set of titanium rods at this price is nearly unfathomable. They are very light, and (i'd hope) just as strong as the LF3 rods are/should be. excellent find for sure.
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