Reliability of 260whp?
 

For the engine/drivetrain, the car has an FMII setup with a GT2560 (inconel studs) on the stock 1999 1.8L, stock 5-speed, big Mishimoto radiator, 700cc denso injectors, Warlbro 190HP fuel pump, and an OS Giken LSD. I have been reading my ass off on here and there is a bazillion pages of great info. From the vast majority of the posts I have seen I see 250/260whp referred to as much more reliable versus the 300whp+ range. That jump seems to be the breaking point for a variety of parts. Okay, so I plan on keeping mine at 260whp to play conservative and it seems to be about the right goal for this setup.

The engine has the stock bottom end and I have a stock 5 speed (another weak point I know). Will be getting it dyno tuned within the next month and shooting for 260whp (w/ 93 octane <3 Texas!). The car also has 100k miles on the motor and tranny, which seems fairly common.

Obviously it is also massively dependent on the driving. For a street car is there any kind of reference as to how many miles it should last? What should I expect to go first? I've already replaced many of the serviceable items (CAS, fuel pump, alternator, coils, etc). I am concerned about the stock bottom end though and the 5-speed. Not sure if it is worth it to pull them and be proactive on anything. Seems like a better option would almost be to push both until they blow and then just get another. Built motors get retarded expensive for the Miata.

I stumbled onto a great thread a few months back that listed the expected whp break points of all the components on the car. Haven't been able to find it again though. If anyone has a link to that it would be awesome.

The car is an Exocet, but basically a Miata without the body for this discussion.

So, what should I be expecting in regards to reliability and any ideas/advice on what the weak spots are for this hp range?

Thanks ahead of time for any help!

Stock bottom and 5 speed...it's not if. Its when will your project explode, IMO. Might last a week, might last 3 years. Almost impossible to estimate life span. 10,000 variables.

Pretty much what I was thinking, thanks for confirming it.

I have seen a few people supposedly rebuilding 5 speeds with higher strength components. Is a 5-speed possible to rebuild to handle 250whp reliably, or you pretty much have to go to a 6 speed?

For that power range on the bottom end, am I just looking at billet gear oil pump and new rods, or is there anything else that would be essential?

About the limits you want, but I'd be more concerned about peak torque. Probably fine if you're smart.

Please elaborate on that! What should I be avoiding with peak torque?

Over 250. Unless you like banana rods.

Gotcha, thanks!

https://www.miataturbo.net/build-thr...-gt2560-90380/

check out this build, before the built motor and upgraded turbo he was about 260whp with low torque. Good power and easy on the rods.

Look up dvcn on here. With his trap speeds he has over 300hp. However, he has a pretty large t3/t4. He doesnt have the huge onset of torque between 3k and 4k rpm like most smaller turbos do. I was running 19psi on a 2854 sized turbo and the "all of it" below 4k rpm was there, and i ended up bending some rods.

OP is this the thread that you read: https://www.miataturbo.net/general-m...ts-part-81560/

If so, you'll have seen the adage that 'torque breaks things, not HP'.

Out of curiosity, is there any reason you're shooting for 260 hp? ie how did you reach that number?

Do you know how long he ran that setup for?
I remember seeing his thread then and he did everything by mistake on his own accord. I think 18psi said that it was a pretty good timing map for being a mistake. I think he copied a hydra map he found.

OP it depends on what you want... low end torque is what makes something fun on the street because that's part of your usable powerband. If you have ebc, you can always add boost higher up in the rev range to increase HP and keep torque steady, but that's way better for a track focused build than it is for a DD. Then again. most folks running these setups do a rods only build. I think Savington has done so on his 250 hp track build.

You fuggin rock! That is the thread I was looking for.

I'm shooting for 260whp because from what I have read that is what the FMII/Hydra can do effectively and it happens to be at the max of reliability for a variety of other parts. It seems beyond that it gets really expensive to play and I'm cool with 260 for now. With just the base tune I'm assuming its about 230whp right now and it is already stupid fun with a 1500lb car.

Yeah, that is exactly what I am trying to avoid. It seems you have to pull the engine to do the rods. Then it just starts a cascade of things that start with, "Well, since I already have the motor out..." And $3,000 later...

I'm sure I'll be there eventually, just trying to delay the inevitable!

So the general consensus seems to be keeping torque well below 250 ft lbs and things are substantially more reliable. I'd like a little more torque, but that seems to be the right path. I've been looking at dyno sheets for 1.8 FMII setups and they are all over the place. Curious to see where it ends up with a good tune.

have you even driven a miata with even 200rwtq?

I ran a gt2560 on a junkyard '96 motor with a MS1 for a long time without any issues (+10k miles I'd guess). I eventually parted the car out and went a different direction with it. You're definitely pushing the limits at that power level, but it can be done successfully. It's certainly no gaurantee, but it's at least another datapoint for you.

Attachment 229885

Car is a 1500lb Exocet with an FMII 1.8 on a base tune and I'd be willing to bet it currently has about 230whp/200tq. My fun car before this was a track prepped C6 Z06, a torque monster.

https://cimg6.ibsrv.net/gimg/www.mia...c001cca633.jpg

Very cool and thanks for the info!

I believe that the FM dynos are thought of as.... how should I say... optimistic...

The shop I am going to in Dallas has a Mustang Dyno AWD500DE. I'll post up results of the base map run and after the tune. Very curious myself to see where it ends up.

250whp on a Mustang dyno in that thing is going to be ummm.... blisteringly fast.