upgrades for a Sebring M45?

[I<3flippyheadlights]

Right now I have a Sebring M45 installed on the car. The 5 pounds of boost is fun, but I want more.

Currently it is controlled by a voodoo, 7 degrees of timing and stock 1.6 injectors. I'm putting on a MSD box to have better timing and will swap to 1.8 injectors.

I plan on ditching all the aids and going megasquirt (hopefully in the next few months if one pops up) but for now, the aids will do. Once the MS is installed, I'm sure I'll make some more power with a cold side intake and proper tuning.

But, I want MOAR BOOST! How do I do that with a Sebring m45? The things are ancient and it looks like no one carries parts for it. I'd like to get a bigger crank, but know nothing of how to acquire one of them. Could someone explain how those work?

I also bought a smaller pulley and found out it was for a JR kit. Those don't fit on the Sebring, do they?


TL;DR
I want more boost out of my m45 sebring. How can I do that?

[Agent☣Orange]

No matter what you throw at it, you're playing a game of diminishing returns. You can get this and that from injectors to fuel pump to pulleys or intercooler but you can't buy your way out of the fact that your SC is 45 cubic inches and designed to spin reliably at a certain RPM.

When you ask about a bigger crank, you're talking about a larger crank "pulley" that replaces the stock Miata crank pulley. This would spin your SC a little fast for more output. Alternatively, the SC nose pulley could be replaced with a smaller one for the same effect (although I now undersand the old Sebring might not accept a smaller nose pulley).

Conceiveably one could combine both larger crank pulley and smaller nose pulley to gain more power but the SC would be spinning beyond its maximum RPM and will push a super hot charge before it shortly self destructs. You'd also be pulling a lot of timing with this setup which kind of cancels out the added boost anyway but I suppose you could dump a bunch more money into a water/meth injection kit.

The thing is, you can open the hood and pour in buckets of money but the return on investment is going to be diminished. If you're really itching to spend money and want moar power, enjoy your SC as it is and start collecting turbo parts.

[Martin]

Aaaaaand this is why the M45 kits disappeared and were replaced by MP62 kits.

[Agent☣Orange]

The M45 is a very popular supercharcher. It wasn't like it was bad and then replaced with the 62. Eaton made a range of superchargers at different price points and power and you'll find the M45 configured to fit several different cars including that little Mercedes roadster with "Kompressor" badging.

It's a great little SC but my point is that if you want to make more power, don't waste a lot of money on little incremental gain, possibly shortening the SC's lifespan, buy a bigger SC or go turbo. IMO.

[Martin]

I was only referring to Miata market. We wanted moar!!

[I<3flippyheadlights]

I'm only thinking of upping the boost a little. If I go megasquirt, bigger injectors and add a bigger crank, I an have some fun at 8psi. The megasquirt and injectors will go towards the future turbo.


I just want a little bit more for now. I'm not gonna pour buckets of cash into a supercharger, that would be dumb.

[Phatmiata]

Let's line up our Miatas some day and see where we are at?


Disclaimer
Professional Drivers Closed course.

[I<3flippyheadlights]

Let's line up our Miatas some day and see where we are at?


Disclaimer
Professional Drivers Closed course.


Sounds like a plan. Don't be upset when your precious LE loses to my old, beat up miata :P

[WASABI]

Sounds like a plan. Don't be upset when your precious LE loses to my old, beat up miata :P

Better let him win or....:ban:

[I<3flippyheadlights]

Better let him win or....:ban:

Gonna do my best to get a car length on him. But it will be funny watching two old miatas with tiny superchargers race. The turbo guys in the club are gonna lolololololol

[BoBo]

You could put standalone and maybe gain 15-20hp + a higher boost pulley if that's what your looking for .But in reality there is a small improvement on the MP45 and most roots type superchargers.Like the other guy said, superchargers has its limits. It would be a better investment to save up for turbo money if your not planning to buy another project with a turbo. I had an 89 Mr2SC with 145hp from the factory, it was a fun and fast car.But eventually I wanted more power. Before I sold the car I was pushing around 180WHP on 89 mr2, but It took a J-spec motor with Head work, high boost pulley,and good tuning. Everyone told me to just put a turbo and be done with it.However, in my case it made sense for me to do it because I already own a 91 Mr2 Turbo pushing 355hp before it was even stroked.

My 89sc was a fun at the tracks, but Blower was working too hard and too hot. I kept running low on oil for the blower, and I knew I was overworking the blower. I didn't care at the time because I had x2 complete 4agze and x1 2.0 3sge in my storage and many other parts. OP if you don't have a spare blower, I would just leave it alone and enjoy it while its working. Your car is faster than the average miata. I test drove a 93 with a JRracing before and it had a pretty good kick compared to my slow 96.

[vindi49]

At the moment you're probably at about 150 to 160bhp? Please bear in mind I'm quoting UK
Rolling Road figures and I know these seem to be measured slightly differently to in the US. Getting more hp out of a 45 charger is pretty easy. At 5psi you are actually below the top efficiency you can get, and they can be safely spun to 15psi IIRC. They have been spun to 21psi for extended lengths of time by several people, yes they need servicing more and it will shorten their life but one of the guys in the UK had 217bhp for over 18 months and used his car for track as well as road, so it didn't exactly have an easy time.

There have been smaller nose pulleys available in the past for the Sebring chargers but as far as I am aware none are on the market at the moment, so unless you stumble across something second hand or have something made, that's out. You still have the option of a crank overlay pulley, they are available from Track Dog Racing and would be an easy way to up the power. Being honest, they are that cheap compared to the charger kit and mega squirt that it would seem daft not to get one! I can't honestly remember how much they gain you, but it would get you to somewhere in the region of 180bhp for under $200 so if you are going to a mega squirt anyway I'd do it. That's what I got out of mine anyway, and 4 years later the car is still being run (by someone else) as a daily driver having covered a lot of miles and 4 or 5 track days a year throughout that time. No mechanical issues at all, apart from a failed clutch which may or may not have been connected.

Russell.

[I<3flippyheadlights]

Well I picked up a MS3x. I plan on getting some bigger injectors (rx7 440s) and get the thing tuned. I'll keep my eye out for a bigger crank pulley in the mean time.

[jimj64]

(Edit) Oops, sorry didn't notice this was an older thread

To get more boost out of your M45 you need to spin it faster, that means either a smaller nose pulley, or a larger crank pulley.

Track Dog Racing sells a 150mm crank overlay pulley (stock is 130mm). TDR also sells smaller nose pulleys, but I don't think they will wok on the Sebring unit, but you should call Gary at TDR and see what he says, he'll know which ones will work for you.

Please keep in mind that the M45 will max out at approx 190hp, to do that you'll need to overspin the M45 and that will shorten its life expectancy. I'm sure if you tried hard enough the M45 couldbe pushed further but nit without intercooling, proper engine management and seriously shortening its life expectancy. If you'll be happy 190hp, I say go for it, if you're going to want more I would seriously consider either going to an MP62 or a turbo.

[Agent☣Orange]

It's okay to revive an old thread if it's relevant. You're right about the basics: spin an SC faster and you can get a little more output to a minimal point but then you'll be thinking about other components such as a beefed up lower along with more fuel and a computer to handle it all. The M45 is a solid, little SC at 5lbs but is in no way capable of pushing 21lbs. That's turbo territory and remember the 45 in M45 stands for a mere 45 cubic inches.

Sure, one can overspin any SC for a short time but IMO, just enjoy an M45 at 5-8lbs or invest in an MP62 or turbo. The return on an overspun SC is not proportional to output as its efficiency diminishes quickly the faster it's overspun.

[jimj64]

Sure, one can overspin any SC for a short time but IMO, just enjoy an M45 at 5-8lbs or invest in an MP62 or turbo. The return on an overspun SC is not proportional to output as its efficiency diminishes quickly the faster it's overspun.

I totally agree, I really enjoyed mine @7psi, I now have a diy turbo and in a way I miss the M45, when I was running the M45 I had a hydra with 440cc RX8 injectors, DDM works airbox, 62.5mm nose pulley and a TDR intercooler. Sadly I also had a full 2.5" exhaust and the exhaust was just to loud for my taste. The same exhaust with a turbo is nice.