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What was your design intent and how close did you get?
My intent was to build a car with all the creature comforts, safety features of the original Miata but with 2x+ the power for the street. My power plant was an LFX from a Camaro with 21K miles. It was in my wife's car. She had owned it for a few weeks when she was rear ended by a box truck. I was originally going to swap it into a 240Z, but couldn't find a solid shell. With V8Roadsters' help I settled on an NC.
As for creature comforts, PS, PB, ABS, AC, functional dash, Cruise Control, windshield washers and paddle shifters. Added a 9 inch android tablet that runs Torque app and GPS.
For performance, I kept racing cats and all smog gear so I can even pass emissions. A tune puts something over 300 HP at the wheel. My first spirited adventure in the car told me the suspension was its weakest link so I added coil overs.
I drive the car daily and have put over 7K miles on it. My only maintenance is has been twice rupturing the PS pressure line bouncing off the steering hard stop.
Didn't mean to frighten anyone off with my post. I am really interested what others are doing with their cars as well as those seriously considering the swap.
like you, we wanted a car that could do everything it did before doubling the horsepower. our lfx conversion was the first NA "street" car. carnut169 built the first lfx NA but it was a racecar. there's a whole lot of complexity to get everything to work (PS,AC, etc) and we were on the bleeding edge. our car never did have cruise control or ABS brakes, so we didn't go there. it's easily the most capable car i've ever owned. it can do anything i want it to do.
My design intent was to build a fun car that was useable every day and would have:
1) The Classic looks of an old British roadster
2) The practicality of a modern Japanese car
3) The soul of an AC cobra
4) Hit a power to weight ratio of 400 hp per tonne minimum
5) Achieve OEM levels of reliability
How close did I get?
I feel like I hit all of them except number 4.
My choice of engine was a 331 ford stroker it makes about 425p and about 335 hp to the wheels. What I failed to understand before I built the car was just how WELL the Miata can handle the power (when fitted with an Eaton Tru Trac diff) and good rubber. The 335hp to the wheels is easily absorbed by the chassis and as a result the car is capable of taking more power.
Also the weight of the car ended up at 1260kg converted i(its an NB Mk2), which is normal but higher than what I would have liked. I Ideally, I would have liked it around 1100-1150kg.
So to make it move more enthusiastically I need to squeeze some more power out of my engine.....I have a cam upgrade (234@50 ED Curtis Cam) and intake manifold porting on my TFS R intake (to go from 265 to 310cfm of flow) in flight to help it to do that. It will hit 460-470 fwhp when done, which is better but still short of the ultimate goal.
The golden ratio for me is about 450-500hp/tonne.....which is the old 427 AC Cobra ratio.
In a ford configuration I would need a very highly strung ford 363 ford stroker to get there (will need about 550-600hp). But this would likely spoil the driveability of the car too. An LS3 engine would be better as it has extra capacity and can deliver a solid 525hp in a crate engine.
But these are just academic exercises. I am super happy with it, it does everything, anyone can drive it and its so much fun. Plus its super cool and different!
engineer, it sounds like you are well on your way to reach your goals. I have found the chassis is very capable and quite civil until you demand otherwise.
I expected to hear more from people simply wanting a race car. I guess many weekend races limit the amount of modification.
I LOVE this build! I am impressed with you going to an LFX, and using all the OE electronics. Looks very well done!! I'm doing an NA with LS1, so there's not alot of onboard stuff in my 93, which makes it simpler, but I do wish i had things like traction control, and better ergonomics. Great job man!
I'm at about the 75% mark on mine... I'll definitely report on goals and if I met them, but it's looking good so far! I wanted to copy Shelby Supersnake specs and have aggressive & sporty styling that matched my digital render... More to come soon.
07-29-2021, 08:27 PM
What was your design intent and how close did you get?
