Originally Posted by cordycord
(Post 1618738)
--I've read OEM ECU's do some really exotic things with their mapping, such as leaning the Hell out of the engine on tip in and then dumping lots of fuel after. If I remember right, part of what Ryan was trying to get around were ECU-based limitations, and maybe some of these quirks.
The ideal state would really be to have all of the A/F mixture combust at once where you don't have to worry about burn rate. This is called Homogeneous Charge Compression Ignition. Google it, it's neat tech, but still in the infant phases of development. To my knowledge, no OEM has gotten this to be a production viable option as its extremely sensitive to temperatures, A/F mixture, compression ratio, etc.
Originally Posted by cordycord
(Post 1618738)
--To make things easier for my brain, I liken PI to DI like the jump from carbs to TBI. Are you saying in your other post that other car groups are taking direct injection cars and then adding port injection via piggyback? I think some of the MSPNP units can run additional injectors for Miatas, like PI + TBI. Care to expand?
Originally Posted by cordycord
(Post 1618742)
Would an extra injector in the intake manifold work, or is that too easy? DI + PI, cleans the valves, adds the HSPRS. I look for simple solutions because sometimes just remembering to tighten bolts is too much for my brain...
https://zzperformance.com/products/l...tor-controller |
Awesome info being shared here.
I considered several options when deciding which way to go on this. I quickly threw out the idea of a single auxiliary injector pre-throttle body for fear of uneven distribution between cylinders. I considered adding PI while retaining the DI, controlled by something like the split second system, and that would be an attractive option for a street car that wants to retain the factory ECU and systems, but it didn't make sense for this application - an added layer of complexity and still stuck with the limitations of the GM ECU. I don't speculate on dyno numbers any more than I speculate on lap times (i.e. never ;) ). But, the supercharger is currently off the motor, and I plan to get the Haltech up and running and work through setup on the majority of new systems before reintroducing boost. So there's a good chance I'll end up dynoing the car while NA as part of that process. However, it's unlikely that I'll be at the same dyno as I have been previously, and there will be some other variables that will have changed. For example, with the change to a universal ECU, it didn't make sense to retain the GM throttle pedal and TB and have to work out the calibration and quirks of those - far easier to convert to a well known TPS and DBW TB. So I now have a TPS on the Tilton throttle pedal and made an adapter to fit a Bosch throttle body from a Porsche 997 application to the LFX intake manifold: https://photos.smugmug.com/2020-Q1/P...IMG_5617-L.jpg https://photos.smugmug.com/2021-Q1/P...IMG_7419-L.jpg https://photos.smugmug.com/2021-Q1/P...IMG_5784-L.jpg |
Originally Posted by ThePass
(Post 1618771)
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So. I have a slightly off topic question for you. Since you not using the OEM trans, or management, or anything anymore at this point, and since the car has been down for over two years, do you ever wish you just went with an LS?
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Originally Posted by Oh4One4
(Post 1618780)
So. I have a slightly off topic question for you. Since you not using the OEM trans, or management, or anything anymore at this point, and since the car has been down for over two years, do you ever wish you just went with an LS?
A) No way to avoid that the V8 is two cylinders longer. I can't move the engine through the firewall in Limited class, so those extra two cylinders would hang past the front wheels and be worse for weight balance. If I reach a point where I determine the juice isn't worth the squeeze to get the LFX to my power targets, I have a plan B in mind (always thinking several steps ahead), but an LS wouldn't be it. B) Going the path less traveled has given me a ton of opportunity to face new challenges and learn and grow as I work through them. This car has been my university for the last 15 years. Wouldn't trade that for anything. I've probably said it before, but to reiterate... the LFX is an amazing option for an out-of-the-box reliable and under stressed 300whp. If I were building a car for just driving enjoyment, I'd leave it as GM intended it and run it all day. There's more to an engine package than a power number, and the LFX has just the right amount of low end torque and smooth delivery to make the car really alive yet drivable. The only reason for all the extra hassle documented here is because this car's goal is to compete against big power TA cars and exotics at a FIA Grade 1 Formula One track (read: massive straights where nothing plays to the Miata's strengths). |
For some reason I forgot you were still in Limited. That's all fair, even if you're hanging hanging a super charger off the front of the engine and adding an intercooler. It should still weigh a bit less than those extra two cylinders. Fab experience is worth its weight too. Very excited to see it back out turning laps.
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Any new updates? Fantastic build.
I just finished an LFX swap in an RX8 and am loving the combo. The only slightly novel thing I did was fit a TR3160 to it since everyone seems to hate the AY6. |
I remember seeing this thread when I was building an LFX Camaro 8 years ago.
Lola the V6 supercharged 15 Camaro. Think we chatted a few times actually. super cool to see it still relevant. |
OP, what oil would you recommend for track use? Hard to find good LFX track experience out there.
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Originally Posted by txbdan
(Post 1648385)
OP, what oil would you recommend for track use? Hard to find good LFX track experience out there.
Motul 300V 5W-40 for the engine, Transmission and diff got Motul Gear300 75W-90 and the cooling system gets a mix of antifreeze, distilled water, and MoCool https://photos.smugmug.com/2024/Halt...IMG_6018-L.jpg https://photos.smugmug.com/2024/Halt...MG_5766-XL.jpg |
Thanks for the info. What diff are you running again? I'm running the Ford 8.8 and am running 75W140.
I'm VERRRRRY excited to hear about the latest build and how its going! |
Originally Posted by txbdan
(Post 1648447)
Thanks for the info. What diff are you running again? I'm running the Ford 8.8 and am running 75W140.
I'm VERRRRRY excited to hear about the latest build and how its going! |
Originally Posted by ThePass
(Post 1648480)
OS Giken in development.
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Originally Posted by Wingman703
(Post 1648481)
Do you have any more information about this? I've been trying to decide between an 8.8 and Getrag, and the lack of a good diff to put in the Getrag has been it's major sticking point. Quaffe makes an LSD for them, but the results I've seen from the people that have tested them have been sub par, especially for the price. Being able to drop in something of OSG quality and reputation would be huge.
So I don't have a timeline yet on when we'll have them done, but it does finally look like it's happening. |
Why not use a Ford 8.8? It's pretty light weight, lighter than the stock RX8 diff at least. It'll hold up to anything and LSD options all day. Lots of shops tune OSGs, I'd talk to ShaftWorks. I'm running a Torsen T2R, but will prob do a tuned OSG at some point in the future. I haven't tracked the car yet so no idea how it'll work.
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The Getrag is lighter, and has better exhaust clearance. The exhaust clearance doesn't matter for me now since it's side exhausts, but there are lots of guys running the Getrag option.
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That's true, it is a big ol' thang.
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