I know that 13lbs of boost on stock sequential and/or parallel twins is going to be different than 13lbs of boost on a single turbo. But can someone explain some of the differences. Like will it be safe to run 13lbs on a single turbo as it was to run 13lbs on the stock twins? Trying to decide on either the T04s or t04e XS Engineering turbo kits. Would I need to upgrade the fuel system. I already have an upgraded fuel pump, actually check out the mods in my signature. Thanks for any help. I would love to have major HP. But does anybody know the difference in lag between the T04s and T04e? Is it jsut a couple of hundred rpms?

 

The stock twins are not very efficient at higher boost level, at least compaired to a properly sized single. As a turbo compresses the intake charge the charge increases in temp, if the turbo was 100% efficient then the charge would follow the gas laws (as you compress a gas the temp goes up). In the real world no turbo is 100% it's more like 60-80%, the lower the efficiency of the turbo the more heat is added to the charge. Since a properly sized single is more efficent at 12+psi the charge temp can be much cooler than the stock twins. Intake charge temp is important for several reasons. First and most important is detonation, the cooler the air entering the combustion chamber the better. Second, the cooler a gas is the denser it is. The point of a turbo is the cram as many molcules of air into the combustion chamber as posable, if the intake charge is denser (because it's cooler) your fuel system has to provide more fuel to maintain the same a/f ratio. If your fuel system can keep up you'll have more power, if not you'll have a dead engine.

So to sum this up, a single can make a lot more power if handled correctly. This probably means new injectors and a new ecu. XS Engineering has claimed 430+ RWHP with some of their kits.

Did this help at all, or am I off in left field?

 

95MX6 is pretty right with his post, the other BIG thing is the increase in Volumetic Efficiency you achieve with running a less restrictive exhaust header/turbine housing/waste gate system.

These are the key area's to making the MOST amount of power with the least possible boost pressue (forget about compressor efficiency for the moment). It is very common to see a 15% increase in VE with a race style tunned length header and either a large exhaust housing or large wastegate as part of your turbo system. Coupled alond with this is an increase in the engines fuel efficiency measured in BSFC "brake specific fuel consumption" this figure goes lower as well when you put on these free flowing components...hence you make the same power on less fuel or more power with the same amount of fuel you used with the less efficient set up. The other big increase (especialy if you have a ported engine) is the higher rpm that peak power is made at...and this is where you make big gains in horsepower with out using high boost. For example an engine like mine makes a lot more power on 14.5psi boost@8400rpm than your normal rotary turbo that peaks at around 6700rpm stock and 7200rpm modified.

Remember power is a function of RPM & PRESSURE & VOLUMETRIC (ENGINE) EFFICIENCY + (other factors including the last post) if any one or all of these variables is higher (except boost in this case to answer the question) then the power will be higher.

 

Before the forum mishap you said you'd mail me some "single turbo math", did you get my email?

Also what is a realistic max rpm without getting too crazy with rotar balancing and what not? Or am I trying to pry too many trade secrects?

 

No you are not prying...I share ALL my information with fellow rotary enthusiasts.

This is the corner stone of how rotaries were developed and is still part of the lisensing agreement today (not that i have a licence!) This is why I get a bit analytical with people who make claims of certain things so all of us can understand if the results are real or otherwise....anyway enough of that.

I did not recieve your e-mail, so if you could please send it asap I will return you an answer within 24hours.

In regards to the rpm limit..it is dependant on many factors, the biggest or first one is relative to power (or chamber pressure BMEP) which bends the crank. The second is rotating mass weight which has a similar effect as rpm increases. And there are other minor things such as oil system (pressure & flow & cooling), apex seals used and engine blue printing...oh and also engine flywheel mass.

Now the biggest limiting factor is rotor clearancing in high HP high RPM turbo engines, once you start going over 7800rpm and you are making over 450 to 480bhp you will experience rotor tips touching the side plates....this is fixed by clearancing. Other rotor problems are gears creeping out...fixed by snap ring.

If you want to exceed 10000rpm with real high BHP (over 800) you realy need a centre bearing crank shaft and high strength crank with all of the above mods, along with high oil pressure etc.

My next project (ready for Xmas) is a 13B with max power at 10500rpm, turbocharged, peripheral ported...stay tunned!

 

Thanks guys. I am going to get the XS Engineering T04s turbo kit, that is why I wanted to know. Any advice on boost setting with the mods I have in my sig?