Just got my apex'i single turbo kit....
 

Just got my turbo kit from Tony today and opened it up. I must say everything is very nice and complete. One thing concerns me though... When looking at the turbine, the intake side is pretty big, but the exhaust side of the turbo is puny. Does anyone know what's up with this? Max? Cheuk??? I'm even wondering if they sent me the wrong turbo by accident, it says RHX6 on it, but the exhaust side looks like it was made for a friggin' honda...

That's probably what helps it spool up so quickly. The Greddy T-78 is also has a compressor that's pretty large compared to the exhaust housing.

Fookn, does your kit allow you to keep the airpump? Are they all like that now?

Nameless, the kit won't let you keep the airpump, as far as I know, only the HKS kits let you retain the airpump.

I've heard of "newer" apex kits that allow airpump retention. I've asked Jason about it, and he's heard of it, and is actually looking into it for me.

Thank you though, if he gets back to me I'll let you know.

Maybe apex is planning to release a new kit in the US soon that will allow you to retain the airpump. The one I got says that the airpump needs to come off (in the crappy instructions) but I don't mind anyways, that just means more flames =)

I think you have the right turbo. I, too, am very surprised how much larger the compressor is than the turbine. Especially since Sport Compact Car keeps having articles about how the sizes should be with 15% of each other. If you open it up, you'll see that a lot of the difference is that the compressor housing is bigger, but the compressor itself is still quite a bit larger than the turbine. I think the turbine is 62mm at it largest diameter, but I don't know exactly how big the compressor is.

-Max

ok so now I need to get a midpipe to go with the rx6?

Weaklink, anytime you remove your airpump you will need a midpipe, or else you will damage your main cat

ya i think I m going to go the borla xr1 RB flange route.

Yes,

The exhaust housing is small. Too small.

Cheuk

it looks like they made it small to speed up the exhaust velocity, maybe to spool the bb turbine at more rpm than a regular turbo?

mike
running 20b fc 2+2

can you run the rx6 with a pfc?

yes just select non seq

1fookntitefd are u running that turbo on a stock motor.

Yes I am, I'm not looking to make big horsepower members like a lot of the other guys on this forum are looking for. I'm just trying to have a good reliable turbo kit with good throttle response. i'm planning to only boost 12-13 psi

With good tuning, I see no reason why you couldn't run 15 psi daily on the APEXi.

The wastegate spring is rated at 1.0 bar = 14.7 psi... so you won't be able to run less without chopping the spring.

Yeah that sounds like the apexi, i'm running 18psi on mine.....thats the sweet spot.

I thought that if you chopped the spring it would run more boost, correct me if i'm wrong or explain how this works

"Chopping the spring" is reducing the spring tension.

So, if the spring is rated for 14psi, it'll take at least that much pressure to compress the spring. Thus, releasing the "wasted" energy to the exhaust, bypassing the turbo.

If you reduce the spring tension, it'll require less pressure to compress the spring (or open the wastegate). Thus, bypassing the turbo with less boost.

The theory is that the more coils in the spring, the more tension (resilience) it will have (assuming same width and material and coil spacing). Taking away some of the coils (or chopping) should reduce the spring tension.
Thus, the wastegate will open up with less boost.

J

J

In very general terms, cutting coils off a spring will increase the spring rate, and pre-loading it won't change the rate at all. For suspension springs, for instance, you are supposed to pre-load by about an inch or two and then measure the spring rate. The rate should remain relatively constant until the coils start touching each other and then the rate goes up (because you are reducing the number of coils at work).

However, I imagine that out near the free length of the spring, pre-load will change the rate (hence the pre-load required for proper suspension spring testing). And removing coils changes the free length and thus pre-load. The A'PEXi wastegate does have a thing you can turn to change the pre-load with a jamb nut to maintain the setting. I haven't played with it to see how this adjustment changes boost.

Given my unfortnate luck with the A'PEXi wastegate for road racing (it sticks, sometimes open, sometimes closed), I suggest switching to the HKS Stainless Steel Racing wastegate. HKS has a reputation for making reliable wastegates and it seems to be the easiest one to bolt to the RX6 kit besides the A'PEXi wastegate that it comes with. Get a wastegate with a spring rate that yields the lowest reasonable boost you intend to run and use a boost controller to run a little bit more than the spring tension.

-Max

How do you know when it's stuck open/closed? No boost vs. spikes? Is the apex wastegate okay for the street?

Is max the only one who has ever had problems with the Apex'i wastegate? I have never heard of any other rx6 owners having problems otherwise with it, which is why i haven't yet purchased a different wastegate. If anyone else has any problems with it, please do not hesitate to post.

At what rpm does the rx6 spool up? How much horsepower can you expect to make at 18psi?

Greddy T88 is the same too.