MRM331

Hi Everyone,

I'm in the process of planning out a LFX build of a 1999 Miata. V8R offers a service where they will reflash the LFX ECU for $550. Do any of you who are familiar with them know if that includes adding in the Miata's VIN? I know it can actually be done to an GM ECU with EFILive but not with the more popular HPTuner software. Which does V8R actually use?

Does the tune also include reprogramming the tach and speedometer outputs to match the Miata tire size and tachometer signal needs? If it does I can use a stock 99 cluster without having to use a decoder box.

I planned on contacting V8R directly with these questions but thought I'd try here first. I'm 75% sure I'm going with the GM V6 over the Honda at this point and 100% sure I'll be starting this build up as soon as I move my family into a house that is attached to a garage I intend on buying.

-Jason

portabull

i think v8r uses efilive. i think you've already made up your mind, but maybe a look at this torque "curve" will convince you once and for all haha. lfx for the win....

MRM331

That's awesome^^^^^

I read one post where someone said the LFX actually feels as though it pulls harder than the LSx through the gears. I saw a few track videos on YouTube of a guy who has a LFX in his RX8 and its just amazing how the thing zips around. I also have looked into the supercharger kits made for it that are out there. The Vortech system can get the Camaro to 410rwhp and 338 rwt. Those numbers are in the V8 arena. Just as a thought exercise I ran the build cost of a V8R LSx build vs. a supercharged LFX V6 build. The blown V6 came in $3500 cheaper than the LSx build.

I think one of the biggest gripes people seem to have with this is why spend all the money for a V6 when you could have a V8. I've found that while you can get a LSx pull out for the same $1500 or so that the LFX V6 runs, the LSx will be a 80K+ mile engine and the LFX may be under 5000 total miles! LSx V8's with comparable miles are near $10K.

I am pretty set on going the GM V6 route at this point. I still have spreadsheets up and running for a Honda JV6, a LSx, a "modern" SBF with a V8R frame, and the LFX but the LFX keeps coming up as the most bang for the buck of all. It does not hurt ether that the LFX has the most recent technology of the four by 10 - 30 years.

-Jason

portabull

another argument (i stole this from carnut169's build thread on mx5atlanta.com).

2400 pounds / 323 is 7.4 pounds/horsepower....
=================
Under $25,000 – pounds per horsepower
2014 Ford Mustang V6 ($22,510) – 11.479
2014 Chevrolet Camaro V6 ($23,555) – 11.514
2014 Ford Focus ST ($23,625) – 12.790
2014 Ford Fiesta ST ($21,400) – 13.807
2014 Hyundai Veloster Turbo R-Spec ($21,300) – 13.930
2015 Volkswagen Golf GTI 4-Door ($24,995) – 14.152
2014 Mini Cooper S Hardtop ($24,100) – 14.603
2014 Honda Civic Si ($22,790) – 14.644
2014 Mazda MX-5 Miata ($23,790) – 14.850
2015 Volkswagen Jetta GLI ($24,535) – 14.910


Under $50,000 – pounds per horsepower

2014 Ford Mustang GT ($31,210) – 8.614
2014 Dodge Challenger SRT ($40,485) – 9.002
2014 Chevrolet Camaro SS ($34,350) – 9.174
2014 Dodge Charger SRT ($44,385) – 9.272
2014 Chevrolet SS ($43,475) – 9.578
2014 Mercedes-Benz CLA45 AMG ($48,375) – 9.842
2014 Nissan 370Z ($29,990) – 9.873
2014 Hyundai Genesis 5.0 R-Spec ($47,400) – 9.883
2014 Hyundai Genesis Coupe 3.8 R-Spec ($29,350) – 10.328
2014 Volvo S60 T6 AWD R-Design ($42,700) – 10.855


Under $100,000 – pounds per horsepower

2014 Ford Shelby GT500 ($55,110) – 5.808
2014 Jaguar F-Type R Coupe ($99,000) – 6.615
2014 Chevy Camaro ZL1 ($55,355) – 7.103
2014 Chevrolet Corvette Stingray ($53,000) – 7.248
2014 Jaguar F-Type S ($92,000)– 7.416
2014 Chevrolet Camaro Z/28 ($72,300) **– 7.564
2014 Cadillac CTS-V Coupe ($64,900) – 7.585
2014 Cadillac CTS-V Sedan ($64,900)– 7.590
2014 Porsche 911 Carrera S ($98,900) – 7.688
2014 Mercedes-Benz E63 AMG S ($99,770)– 7.697
=========================
and here's gearing calculations courtesy of http://www.apexgarage.com/tech/gear_ratios.shtml:

tire diameter: 23.1 (yokohama s-drives, 205/50/15)
getrag final drive ratio: 3.23
mv7 (cadillac) transmission, ratios below

RPM: 7200------------------------------ RPM: 4000

1st Gear Ratio: 4.16 speed: 37-------------20
2nd Gear Ratio: 2.51 speed: 61-------------34
3rd Gear Ratio: 1.69 speed: 91-------------50
4th Gear Ratio: 1.27 speed: 121------------67
5th Gear Ratio: 1.00 speed: 153------------85
6th Gear Ratio: 0.75 speed: 204-----------113

most of the time, i drive the lfx just like a 1.8 bp miata, shift at 4000, from there to 7200 is just for
when you need it. i will confess that i've got maybe 8 tanks of fuel run through it so far, and they all included several "i need it" episodes. it's not like i'm trying to twist your arm or anything haha, but i can tell you - that torque curve is for real....

grubinski

At some point, you have "enough". The LFX I'm sure is "enough". I just wanted something really silly, so I built an LSX. I'm old, and a V8 just does things for me that a V6 can't. Torque is wonderful in a car as light as this. :-)

MRM331

Ironically that's sort of the case here with me. I have built four Ford V8 Miatas and "rebuilt" another five or so at this point. I've also built harnesses for almost 60. My move to this V6 idea is first sort of a need to try something new but also a chance to develop a harness conversion scheme for the GM harness that can carry what I do ahead another few years. The quality of the donor Ford harnesses I've seen is starting to go down drastically the last few years and the prices on line keep going up. I can for see a point coming in the future at which it's simply not going to be worth converting Ford harnesses for these cars when new FPP or aftermarket options start approaching the cost I will have to charge to replace every dried out plug and wire on a donor. Additionally we are already at a point where a usable stock donor Mustang pull out engine is as mythical as a unicorn. While I'm sure people will continue to build Ford-based V8 Miatas the builds will start around a custom engine build. I've done all mine this way and have been very happy (free machine work and labor from my father helps a lot) but I can see the attraction for many in just dropping in a solid oem-built engine that you know you can trust and have never removed even a cylinder head from. Right now this is only an option with the Ford if you have one built ($5000 - god knows where), find a low mile LSx ($5000 - $12000 from what I've seen on Car-part), or a low mile LFX ($800 - $2000). I sort of see this conversion being the "next" 5.0 in that you can build it out for under $15,000 and do it in your one car garage with a set of jack stands and a socket wrenches. While I'm sure that it can be done for less, the LSx really requires you have another $10,000 or so on hand and know how to weld or have the ability to get someone to weld for you. This is a big hurdle for a lot of weekend wrench types who 10 to 15 years ago may have been willing to tackle a 5.0 build but now can't because of the cost of the engine build.

If I don't like it I'll sell it in 2 or 3 years for what I have in it and finally build a LSx...maybe

-Jason

john j

Both myself and one my friends both own or have owned V8R conversions, we both agree my friend and I that our next projects will be LFX V6 engine conversions his is already underway, my wife is the holdup in my starting one too. We both believe the V6 conversion is the next evolutionary step in Miata performance from a street driven perspective. My V8 has breathtaking street- performance as people who have rode with me will attest to it. I just believe that technology today allows the V6 to perform just as well for less cost.