I was looking at the article from Modified mag on the Top Secret Z. I read that they where pushing 450+ hp @ 18psi on stock internals and block.

That is really good news and a statement of the quality and reliability of the VQ engine.

Greddy is pushing 350+ hp @6psi with their TT kit. That prototype car has exhaust, engine management, boost controller, etc. If the engine can withstand 18 psi, maybe 15psi daily, you can forget about SC's. Turbos rule!

A TT setup at the same preassure and power level will spool up faster that a single turbo. That means that the TT will be faster than a single turbo at the same power level.

I can't wait for that TT kit to be available.

 

It doesn't add up.

Think about that for a second. One company (Greddy) REALLY wants to sell turbo kits, but hasn't got it out yet because turbocharging a high compression motor isn't easy. Meanwhile, some other company comes along and puts 18 psi into it? 12 more than Greddy? And to top it off, they only got 450 out of it? Sounds like they retarded the timing a LOT to get that to happen.

Questions:

What else did they do to the motor?

What fuel are they running?

 

The article says they are developing new internal pieces for the engine, so I figure the engine will not last long on 18psi.

For a 10.3:1 CR I think 10-12psi will be tops, with careful tuning and fuel management, maybe water injection.

Anyway, with that boost big power numbers are on their way. We will have to wait and see what happens.

 

just read the article and it's a single turbo. It is also a garrett, the same that is supplying nismo and I believe they make the best turbos.

 

they could of changed out the heads, or put in a huge *** metal head gasket in between, but well wait and see.
franklinz

 

"And to top it off, they only got 450 out of it?"

450 at the wheels. That's well over 500 at the crank.

 

nothing but red X 's

 

its more of a reliability/safety issue.

Sure a company can put out high boost on a kit, but if everyone ends up blowing the damn car up. its not good for business. Greddy is just playing it safe. like everyone should when it comes down to FI.


just be patient. there will be kits made for everyone's tastes. Single, bi-turbo, sc, etc...

each will have their own downfalls. but in the end, we get kits made, and the more products out, the more options we all get.


frankly. i dont mind a lower boost turbo kit if it means the car will last longer when pushed a bit harder than normal...

 

Every once in awhile I see someone say that a twin turbo setup spools faster than a single turbo setup. Are we sure about this? Remember, a twin turbo uses only 1/2 the available exhaust gases to spin each turbo. So now you may be thinking, OK 1/2 the exhaust to 2 small turbos is equal to all the exhaust to one larger one. But 2 impellers are going to be heaveir than one larger one, as you need to duplicate material for each turbo, the shaft for example, you need 2. One larger impeller should weigh less, and spin easier than 2 that are capable of flowing the same amount of air. Similar to exhausts... 2 smaller pipes or one large one. They can both slow the same, but the one larger one weighs less, and uses less material to achieve the same flow. Likewise, one
larger turbo uses less material to achieve the same amount of flow.
So, do 2 small turbos that flow the same amount as one large one always spool faster?

 

True, but then again, when most people talk about TT's spooling up faster, it usually refers to a sequential setup if I am correct. One turbo will be smaller and thus spool at lower RPMs and the larger one will kick in at a higher RPM. Thus the powerband should be smoother

It might not be as efficient as a single turbo kit, but for some people, straight line power isn't all that great. Think about it this way... if someone was making a turn and then all that boost kicks in at one time, they are asking for trouble.

I would love the turbo kit for a Z or an M3 (even though they won't run such high boost). The higher compression with lower boost would IMO be a better car to track (spools lower and a much more linear band) than a low compression car running tons of boost (spools higher and a huge surge in power). This is of course, if you don't use the "bang-bang" method.

 

If you add up the weight of the impellers, they probably will weight more than one large one, yes, but you're forgetting a couple of things. First the energy that runs a turbo isn't just from the piston blowing the gasses out during the exhaust stroke. It's from the gasses still expanding while they're on their way out. And the smaller turbos have a smaller moment of inertia because the impellers are each physically smaller and have less weight than a single larger impeller. In other words, less weight in a smaller physical area is less resistant to rotational acceleration and that equals less lag. The downside is that these physically smaller turbos that spool up quicker will become a restriction sooner because of their reduced size. I mean, that's logical, right? It's smaller inside, so ultimately less stuff fits through it. This is why a single big turbo can make huge numbers but might take a bit longer to do it. Think about Supras. Those single turbo converted ones make truely SICK amounts of power.

Turbo sizing comes into play here... It takes a particular volume of exhaust gasses to spin up a turbo to the point where it's producing significant boost pressure on the compressor side. And therein lies a trade off. You can have a bigger or 'looser' turbine side that will spool up slower and require more RPMs to provide the volume needed to get the turbo spinning, or you can have a smaller or 'tighter' (just a way to think of it) turbine side that will spool up with fewer RPMs but will run out of it's efficiency range sooner once the shaft speed gets too high. Then it'll just be blowing superheated air that won't make power. Think about what it would be like to drive a car with each type of turbine and you'll start to see why some cars are built the way they are when built for a specific use. Toyota was trying to make a car with a broad power band and smooth power transitions throughout that powerband when making the Supra. That way the car would be more stable when drivers would put their foot in it exiting corners. That's why they put on 2 turbos. We've seen over and over that ultimate power comes from a single large unit. But imagine exiting a corner, and leaning into it and NOT being pointed straight when that single big turbo hits it's efficienct range! YIKES!! No amount of correction will save you from the resulting spin.

Sorry for the ramble.... it just kinda happens, ya know?!