I just thought I post some of my findings here for the people.

I'm running the kit on a B18B and I'm running 10psi. I want to run 14psi but the spring in the wastegate actuator will only hold the boost to 11psi before the exhaust gasses push the wastegate open. I dialed some more preload into the adjustable arm and I was able to get to around 15psi.

The interesting part is that I was getting some major boost creep even when I set the boost controller to 6psi. I would still get near 15psi at 7300 rpms.

It turns out that I dailed so much preload into the spring that I actually made the travel of the arm so short that the wastegate could only partially open so the boost would build

I am in the process of trying to attach a Ford Thunderbird dashpot to the turbo since it has a 10lb spring and nearly the same bracket as the Apex'i kit. They are both for IHI turbos.

We'll see how it goes.

 

Thanks for keeping us updated. Any new dynos?

 

Well, when I got the Hondata installed and tuned I had no preload on the wastegate spring so I was only able to make 8psi of boost. I put down 220hp and 217 ft-lbs which is okay but I was really hoping to push 14psi that day.

I dialed the preload back into the spring when I got home. Doh!

The next time I go I'll be sure to post up a chart. I'm guessing it will be a couple weeks at the soonest.

 

I see you are in ATL. Ed tuned my car there last weekend @ dynolab. Where do you plan on going? BTW, my B16 said it was jealous of your LS's torque (only made 170ish at 8psi, but the HP was just a tad bit higher ) Good luck!

 

oh more interesting info, the kit has been discontinued, thats why they were all whored out a couple weeks back

 

Damn, are you saying that the Apexi SOHC kit is out of production? It doesn't matter cause it's identical to the DOHC kit but with a different manifold.

I want that B-series manifold.

Yeah, I had it tuned by Ed at Balanced Performance. Tell your B16 that my LS said it was jealous of you oil squirters!

 

Can't you just use a boost controller, or am I missing something?

 

You're missing something.

The ability of the spring in the wastegate to hold the "door" closed while the boost builds is what determines your max boost. The apex spring is only strong enough to hold the wastegate closed up to 11psi. After that it opens and the boost stops building.

If you use no boost controller, then the dash pot does all the work and you can really only run about 8psi.

It's a pretty complicated system of variables that is best understood in a hands on fashion.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by glagola1 &raquo;</TD></TR><TR><TD CLASS="quote">You're missing something.

The ability of the spring in the wastegate to hold the "door" closed while the boost builds is what determines your max boost. The apex spring is only strong enough to hold the wastegate closed up to 11psi. After that it opens and the boost stops building.

If you use no boost controller, then the dash pot does all the work and you can really only run about 8psi.

It's a pretty complicated system of variables that is best understood in a hands on fashion.</TD></TR></TABLE>
Gotcha, I'm not too familiar with internal w/g setups.

 

Well, I just got back from a test run with the Thunderbird dashpot installed on the Apex'i kit. HOLY ****!!!!!

The spool is VERY quick due to the wastegate staying completely shut during spool. The least amount of boost you can run is 10psi so it's not a good idea to run it unless you have good engine management. The good news is that it will easily hold more boost than I can use with a stock bottom end all the way to redline.

On the Greddy Profec B the low boost **** at a little less than half way will get you around 12-13psi. The hi boost **** set all the way low will get you around 14-15psi.

It was a very easy modification to get it to fit too. Just a bit of cutting and bending of the thunderbird bracket and the drilling of one hole and you are set. About an hour of work I guess.

 

can i use any d series turbo manifold on my ls?

 

Yes but you have to do a little "massaging" to it.

 

do you kno where i could find more info on this?

 

just get the manifold and gasket and line them up and you'll see what needs to be ported, grinded.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by glagola1 &raquo;</TD></TR><TR><TD CLASS="quote">I just thought I post some of my findings here for the people.

I am in the process of trying to attach a Ford Thunderbird dashpot to the turbo since it has a 10lb spring and nearly the same bracket as the Apex'i kit. They are both for IHI turbos.

We'll see how it goes.</TD></TR></TABLE>

has anyone else attempted this? is the dashpot the cylinder part of the wastegate? or can the spring just be changed inside the wastegate? sorry for bringing this back from the dead, Im just really interested in this and want more info. thanks

 

I didn't even know there was a B series kit from APEXi. Is the turbo the same as the sohc one (RHB5) My wg seemed to flake out after a while, i shortened the arm all the way and it'd only go to 6 psi so i just attached a MBC and adjusted with that. It made some good numbers though, on the hack and 8 psi with a stock d16y8 i made 176 whp 173 wtq (about 30 more wtq than greddy and most other d16 kits)

I made full boost by around 4 grand, i wonder what you B series guys are making full boost by if it's the same small BB RHB5

 

i wanted to boost around 12-14, if the wg starts to get all funky before that.. I definetely want to upgrade it. but great #'s nonetheless.