vettereddie

Well, I couldn't pass on the good price for the 10:1 pistons and ended up picking them up. I'm building a supercharged engine and trying to figure out what size pulley I'll need. I already have a spare motor to build so there won't be more than a week of downtime to do a swap and install. The setup will be:

- Wiseco 10:1 pistons
- Crower rods
- Toga HP bearings
- ported and polished head & supercharger intake manifold (free for me)
- knife-edged throttle body
- Greddy / Eaton MP45 helical roots-type supercharger
- AEM methanol injection
- eManage blue piggyback ECU
- tC injectors
- fuel rail (maybe)
- AEM UEGO AF/R meter
- B&M supercooler transmission oil cooler (28,000 GVW)
- Weapon-R secret weapon short intake
- Strup 4-1 headers
- Custom 2 1/4" cat-back exhaust

I've spoken to tech reps at Magnuson, the distributer of the Eaton blower to Greddy and manufacturer of the bypass valve on it, and they gave me proper sizing for PSI, so I know pulley diameter per PSI. What I'm trying to figure out is what is proper boost to run for this configuration. I din't want to run 9:1 compression and have it make no power where I do most of my daily driving below 3200 RPM. It's an automatic if the oil cooler didn't already give that away.

I'm thinking 12 psi, this will run the blower to 12,300 RPM, still under the 14k operating limit and around 59% efficiency, down from the 62% at 7 psi. According to Eaton's calculator, this will bump it up from 134 to 160 BHP. The methanol injection should raise that up more, though I'll be spraying after the blower direct into the manifold as methanol has a tendancy to pull the oil from the sealed blower bearings and sieze it. I'd like to experiment, but pulleys are $125 a piece to get made and will add up quick. I'm thinking of maybe having two done, one at a lower and one at a higher boost to see what the differences are and hopefully reduce some of the risk by going incremental.

I will actually be changing the alternator pulley, not the supercharger one. The alternator is a two belt pulley. I'll be leaving the main drive one the stock diameter and oversizing the supercharger drive pulley to change the final drive ratio. This should help with belt slippage since there will be more pulley surface area to work with, and will not need to be keyed like the s/c pulley is. Right now the drive pulley is smaller than the s/c pulley.

My other option is to leave the s/c alone and get two tunes, one for daily driving @ 7 psi and one for use in tandem with a 50 HP wet shot of nitrous at the track. I'm getting the support tool so I can change maps out and make adjustments if needed in response to the UEGO.

I know some people will say dump the s/c and go turbo, but I've had it on sale here and on club forums since May and still haven't sold it, so it looks like I'm stuck with it. May as well make the most out of it and be one of the few s/c's above 150 HP. I'm asking $1500, so I don't think it's price. I would rather not spend $2300 on a base Greddy turbo + 800 on an intercooler and more for a boost controller unless the s/c sells, the internals alone are already adding up.

deflaytedwayz1

Good luck dude. I don't see the point of raising the compression and slapping on a sc. You think there is a reason that f/i pistons are low comp? And why slap all those performance parts on a car you rarely drive more than 3400rpm? Whatever. Good luck.

JSosa

Your plan sounds good, but why go through all that trouble for a super charger... Leave the bottom end stock and you can save the money for something better, like an ECU, injectors or a fuel rail (if you dont have it already).

The OEM compression ratio is 10.5:1, so leave it as is, a supercharger wont snap your rods like a turbo.

The boost amount sounds good and you've obviously done your homework. I would have saved the money from the pistons, rods and bearings. As for everything else, sounds EXCELLENT. I would love to get my engine polished, not ported, just polished.

One question is BHP calculated from the flywheel or wheels?? If its flywheel than I think 160BHP can be obtainable off an SC but i dont think you will hit the 160WHP. The meth injection is definately a plus.

And as you said things add up, A WHOLE LOT quicker than one would think, I was a victim of this and im now paying the price. My car is at a stand still, its working but my header is cracked, so i have alot of work ahead of me and no time or money to do it.

If you have the charger: DO IT!!! Dont waste your time on the turbo, to complicated, keep it simple and your daily driver will appreciate it.

vettereddie

JSosa, I've already snapped rods and am now on my second engine, so I would be MUCH more comfortable with forged internals. The reason for building the charger is that I already have it and am having trouble selling it for a turbo. It comes with eManage blue so I don't know what other ECU you'd be talking about. I'm not going stand alone an losing my airbags, traction control and ABS. I currently have the Greddy supercharger, tC injectors and Perrin rail and have had them for over a year, so I won't need to buy them.

I'm building a spare motor, not the one in the car, so if I get in a financial crunch it won't ground the car. I'm an electrical engineer, so I do have some extra funding available to mess with, hopefully more so once I get my masters next year. I also did the last motor swap myself in about a week, so if I break this one I won't be too bad off, just throw the stock back in. I've got a spare transmission as well, it came with the first spare motor.

deflayted, I've actually lowered compression from the stock 10.5:1. Yes, there is a reason for lowering compression on F/I applications, it staves off detonation at higher boost pressure. However, it also comes with the nasty side effect of lowering HP when the turbo is not spooled, and the lower the compression the worse it gets. Methanol injection should help reduce detonation chances as it acts as both a chemical intercooler, reducing the charge temperature and acting as an octane booster, slowing the fuel burn rate. I have not been able to find a reliable model for calculating boost pressure, so it's still somewhat of an art. I was hoping to get consensus from the SL community who have had experience boosting 4 cylinder fuel injected engines as a baseline of safe operating pressures.

This is a multi-purpose vehicle, I stay below 3500 RPM during the week to and from work. What's the point of revving up on roads with a 35 MPH limit that are heavily patrolled? On the weekends, there are several drag strips within an hour that have 4-5 shows / races a year for the Scion and import community, hence the higher PSI or nitrous. There is also the extra WOW factor a F/I engine bay brings to shows. I'm going after some big fish and want a little extra on them since I'm not getting bags or a body kit. The people I'm in comp against are still N/A.

This is why I prefer to build the motor:

deflaytedwayz1

My bad man. I totally thought it said 12:1. That's why I was like wtf!?! My bad.

vettereddie

Yeah, boosted 12:1 wouldn't make a whole lotta sense. Not sure what max N/A compression ratio could be achieved, but I'll leave it for someone else to do an all-motor setup.

Icecreamtruck2005

So are you going to run the s/c with meth and nitrous? I think the best setup would be the s/c with the use of nitrous 35 shot for the strip maybe 50 with pistons and rods.
Why don't you use aem fuel controller I think its much better and updated than the old greddy blue emanage. It's worth the money but it sounds like you got the greddy unit with the s/c. Can you adjust the greddy emanage that came with the s/c and is it the same as the aftermarket blue emanage?

vettereddie

The eManage blue is the same that comes with the aftermarket one. It is limited by itself to the jumper and dial settings, but with the eManage Support tool computer program it is fully programmable for injector duty cycle and ignition since it came with the optional injector harness for the xB. It came with the supercharger as a kit so, unless it doesn't have the control I need, I will be keeping blue.

I'm picking up a Greddy turbo kit on Friday (the price was right for a used one, previously installed by PTuning so I don't think it had any operating issues). If I can't sell the supercharger, I'll end up twincharging. I'll do a fit check this weekend. I'll leave the stock 5 psi on the turbo feeding the stock 7 psi of the charger for a 12 psi total boost. I'm interested in seeing the torque curve on that one. I'll run methanol injection and see how it does without the intercooler, then add it later if needed.

If I can sell the s/c, I'll go all turbo w/ methanol injection, front mount intercooler and possibly a nitrous or CO2 chiller bar at a boost TBD.