HELP! With My Engine

[scBlackbox]

Ok My Fellow Scikotics,

Ok take in mind I'm an electrical and audio guy when it comes to cars... I'm definitely not a engine guy... i mean i know the basics... what things are mostly and what they do... but that is about it. I mean you can only learn so much from watching the Powerblock on Saturdays.

Alright, now I have a '05 Scion xB with a automatic transmission with no engine mods except a AEM short ram intake. Now changing the transmission is not an option because I have leg problems that would keep me from being able to drive a box with a manual transmission. Now I am tired of having a slow box with only 86hp to the wheel, I have read all the info on Superchargers vs. Turbos. Now I know that Superchargers are good but tend to be most helpful only in the lower RPMs, and Turbos are the exact opposite they are great in the high RPMs but you have to wait for them to spool up and they put off a considerable amount of heat. Now I am definitely not a engine guy but I know that you can put both on an engine, but what kind of mods would I have to do to the engine to put both a turbo and a supercharger, and would it be worth it? I mean I know it would probably kill my gas millage but the way gas prices are going up, it won't matter soon lol... I just want to know if I put the money out for a Turbo or a Supercharger or even both will it be a worth it in horsepower wise.

Ok Scikotics, give me your ideas and opinions on what I should do, and what I should get, and lastly what mods I definitely need. Thank you for time... I look forward on what y'all have to say.

[vettereddie]

Todd, we need to talk :lol:. I just put up a thread and poll about this same subject. I currently have a Greddy supercharger but am looking to go bigger. You'll want to answer a few questions to help you decide.

- How much are you looking to spend
- How much work are you willing to do yourself (inversely proportional to how much you'll need to spend)
- Are you willing to replace engine internals

On a stock engine, either the turbo or supercharger will woek well, giving you between 30-40% more power. I like the supercharger for the automatic so I don't need to rev the motor as high and to haul weight, but the turbo will give more power and you won't need to deal with belt slippage. A cat-back exhaust will help the turbo, but isn't needed for the supercharger. A B&M automatic transmission cooler would be good either way, no other trans mod should be needed. You'll still get around 26-28 mpg. I'm still selling my Greddy supercharger for $1500, though you'll need to buy a new harness for the 05, mine's an 06.

Either are worth it if you have the money to spend, they really make it more fun to drive.

I wasn't happy with 114 WHP though (up from 82 WHP stock), so I'm building an engine with forged internals. If I keep the supercharger, I'll need to either get a bigger pulley and water injection for intercooling, add nitrous, or put a turbo on the front end to feed the supercharger.

Twincharging can be done, but it's the least cost efficient way to make power and you will need new internals. If I sell the supercharger, I'll be going all turbo, a BOV spring is a lot easier to change out than a supercharger pulley, and the blower loses efficiency at higher boost.

[JoshCrane1]

ive seen a twincharged tc at nopi, but it looked rediculously expensive and inneficient.

[vettereddie]

Can't s't argue with you on cost for a twincharge setup, gotta buy both a turbo ans s/c setup to run it. Efficiency is debatable. What VW does is have the s/c feed the turbo to spool it quicker, then activate a bypass valve and RPM-activated clutch to disengage the s/c above 3500 RPM. Low-end torque, faster spool and turbo efficiency, a marvel really.

I wouldn't be doing that. I'd be running both all the time, with the turbo feeding the s/c. Sounds bad at first, but consider the supercharger operates efficiently only up to a certain speed. With a positive displacement blower, feeding it pre-compressed air doesn't make it work harder so the s/c can stay in it's efficient operating range and output a greater boost pressure. Conversely, since the turbo needs to put out a lower compression, a smaller one can be used that spools quicker with less lag, even without being spun up by the supercharger. I'm not sure if with the supercharger actually sucking air through the turbo if it would help spool time or just create drag.

I will most likely just run nitrous through the stock supercharger, which will hopefully also have the effect of an intercooler as it passes through the system.

[scBlackbox]

Brian,
Was up man... I want to thank you for helping me out. I don't mind doing the work my self and in the end i feel better b/c I did it... I have a cherry picker and engine stand ... and money wise is a issue but hell if i have to buy a little here and a little there and put it together in the end...i don't mind. I just would love to have the set up of both a turbo and supercharger... cause I just love having something that is different .. thats the one thing I miss about when I first got my box... now everyone and their grandma has one around here... and dude i know your up there in Maryland but if you ever do come to the south be sure to let me know I would love to see your set up and if you need a garage in the south, my garage is open to ya...

Now on to what you think i need to do to the internals of my engine to prepare it for a supercharger and turbo... and what kinda of s/c and turbo set up do you think i should do ... the one where it cuts off the s/c at a certain RPM or like your doing where the turbo is feeding into the s/c and if I do all this should I also go ahead and get a upgraded ECU or could I just get away with a stock one with a piggyback ECU add-on?

I thank you again b/c with out people like you helping me I would be up shit creek with out a paddle and a tore apart engine block...lol. I look forward to hearing what you have to say... and if you get your engine done right and you can't make it down to the south ... take some good pics and show off your hard work...

- Todd

[vettereddie]

No problem, just don't think I'm any kind of expert. I'm an electrical engineer, not mechanical, I just like getting my hands dirty.

For internals, you'd need a custom piston, I'm getting mine from Wiseco. Figure out what driveability you want, that will be inversely proportional to compression ratio. I wouldn't recommend going below 9.5:1 on a daily driver, otherwise it will be rough at lower RPM's. Of course, for track only, 9:1 can handle more boost. I'm running a milder 10:1. Rods are the #1 thing to upgrade, the stock ones are toothpick thin, I've already broke one set which is why I'm running n/a at the moment. Crower makes a set for the xB but you will need to notch the bottom end of the cylinder wall for proper clearance. If you go overbore on the piston, you'll also need the block bored out, and re-honed either way. Also replace the main and rod bearings, there are markings on the crankshaft that tell what size is needed. I'm still trying to find head bolts and gaskets better than stock.

To twincharge, the more efficient setup is to run the supercharger into the turbo until the mid-rpm band, then disengage it via electronic-controlled clutch. With a roots-type blower, space will be tight since you'll need to run the S/C outlet into the turbo and not directly into the intake manifold. it's really not worth the $$ to try and set this up, everything would need to be custom fabricated so unless you know a machinest I would not attempt this.

I was contemplating the serial setup with a turbo feeding the supercharger because it should work with any bolt-on turbo to the Greddy s/c since it leaves the throttle body in the stock location. I would need to find a used turbo kit to make this economically feasable, preferably under $1500.

What I'm most likely going to do at this point is throw on a bigger pulley, run methanol injection and possibly a 50 HP nitrous shot for the track. I calculated out the current greddy setup yesterday, it uses a 1:1.665 final crank to s/c pulley drive ratio, meaning that at redline, the s/c spins at 10k RPM. The Eaton MP45 is designed to spin up to 14k RPM, so by going with a bigger pulley I can get close to the operational limit. I'm not sure yet what this does to HP, I'm calling Eaton to figure out how to read the performance map for them. Eaton did include a tool calculator, and by it's math there will be a jump from 134 to 160 BHP.

When I say go bigger on the pulley, I mean the secondary alternator pulley, not the supercharger one. The Greddy is a two belt setup, with the main belt going from the crank to the alternator, water pump and A/C compressor. The alternator pulley is actually two pulleys on the same shaft of different diameter. The secondary pulley goes between the alternator and supercharger. Essentially, the alternator would spin at the same RPM as stock, but the secondary would be enlarged, changing the ratio between it and the s/c and spinning it faster. This is better than reducing the s/c pulley size because it gives more surface area for the belt to grab and hopefully less slippage.

[Krazylowgsx]

first of all, on a xb the turbo is small enough that you dont have to "wait" for it to spool. i've had a s/c on my xb, and it was fun! i sold it, and now have a turbo kit siting in the garage for it. my main reason for boosting is show. the xb isn't going to go fast unless you build the motor and do some other mods. i think either way you go, you will love driving it more than you do now! i little turbo might have a tad bit more power up top, but its not going to be a huge increase over a s/c. on an xb, both are winners in my book. i'm a turbo guy.. always have been, always will be, but i'm not against s/c on an xb just for the fact they are reliable and the installation is right there under the hood in your face. a turbo instal... now thats a whole lot more complicated and if a problem ever arises, be prepared to crawl under your car. its all up to you my man!

[Hotokuken]

Find out what you want from the vehicle. I wouldnt recommend supercharging, and the reason is simple. Most superchargr guys usually end up going turbo or twin charging. When going with a turbocharger its pretty much unlimited the smaller the turbo the more power on the bottom end but it will kill your top end the larger the turbo the more power on the top end but it will take longer to reach peak boost. Research into it and then you can contact turbo manufactures to pick the right turbo based on their flow maps. This will allow you to balance power/lag for the turbo you want for your application. Engine internals are just saftey precautions you can turbocharge any engine without internal modifications its all in the tune and how you drive that will determine how reliable it is. if you can tune it yourself then that is the best way to go if not then you will end up spending thousands of dollars fully building an engine or fine tuning it to the point that god himself wrote the fuel/ignition maps. iIf you dont believe me check out homemadeturbo.com ive been a member there for about 5 years now. Thats where i started to learn about turbo charging.
they are mainly a honda/acura site but turbocharging is universal.

Buddy

[Dragon Wagon]

If you want an immediate power boost switch the 1st gen for a gen 2. The 1st gend have depreciated so little that it probably costs less to get hte power by upgrading to a gen 2 than modifying the gen 1's engine. Plus if you wanted to go up from there you could.