2.5L suitable for endurance racing?

[GeorgeR862]

I’m intrigued by the idea of doing a 2.5L swap into an NC for a low buck endurance racing series (i.e. Lucky Dog, Lemons) but I’ve heard from one of your competitors that the 2.5L is a poor choice for endurance racing… if I understood them correctly they implied that the long stroke design tended to beat itself to death in long races. Is this a valid claim? If so, are there steps that can be taken to mitigate the issue (upgraded engine internals, avoid boost, shift at 6K, etc)?

Thanks!

[Brian]

The 2.5 is very durable. Drive it smart, take care of it, and it will give you many years of endurance fun. Drive the torque curve, not peak rpms.

I know customers racing every weekend on 2.5 with 50,000 track miles on the motor. I don't expect ANY motor to last much longer than that at full rpm use. Folks certainly blow up sooner but when you dig into the details so often that turns out to be a missed shift and they spun the motor to 15,000 rpms, or oil starvation, or a number of other failures that are not really about this motor in particular. And typical track 2.5 is a junkyard motor that had 30,000 or more mystery history before installation in a NC Miata. Plenty of threads on this where customers have posted their details, like 'brandontrek' at this Miata.net thread with 45,000 track miles on his 2.5 conversion (and it was a used motor to start with that came used with 30k miles):

https://forum.miata.net/vb/showthread.php?t=723993

Don't miss a shift, upgrade the water pump and radiator, do upgraded oil pan (or our new oil pan insert that is a low dollar fix to oil starvation), keep the rpms reasonable, etc. There is really no reason to buzz the 2.5 above 7000 rpms, with reasonable cam choice the meaty torque that makes it quick out of the turns is all below that 7000 rpms. Set a reasonable redline in the reflash of the motor and don't money shift, etc.

https://www.good-win-racing.com/Mazda-P ... -3529.html

[GeorgeR862]

Thanks Brian! I suspected as much but appreciate hearing so from you.