We are working on a custom lower/upper manifold to allow for the additional port injection for those that are wanting/needing it. As far as going over 500hp you can easily do that alone on GDI as we have a customer car that is doing 625whp still on stock GDI injectors and HPFP. The bk1 lower doesn't fit onto the bk2. As far as fuel control that is all being done directly through the stock ECU and can be handled/tuned by any Alphaspeed dealer near you when your ready to tune.

 

If anything, port injection would clean the valves.

I assume you guys have tried tying the port and direct injectors for the signal/trigger? Are the GDI injectors low or high impedance?
If you guys can get that to work, then I would assume you would be just need to scale down the fuel map for a baseline tune.

 

Im actually doing a build now. just wondering what direction to take. I see most people build turbo setups on stock motors and dont make over 500. Wondering if its rods or too much compression. The other side of it is the fuel. thats why I was thinking install lower intake and do both DI and port.

 

Well let me know if I can help with supplying parts as I handle a lot of the communities engine builds or supplying the components they need for their builds. Most people that boost on stock motors aren't making over 500 because your looking at very weak piston ringlands and especially for an engine that wasn't built for boost from factory. With GDI you can keep the same compression and your going to push to the fuel limitation before you push a built engine limitation. Trust me i'm with you and the stuff just isn't cheap especially for limited runs or 1 off projects.

 

Im looking for a crankshaft. Does any manufacturer make a high comp piston?

 

Looking for a brand new factory crankshaft? I have 1 on hand. As far as high comp, how far do you want to go?

 

On the 300zx, some company (it's been a while) use to sell a throttlebody spacer to have 2 auxiliary injectors just after the throttlebody. Not sure how they controlled it. I would imagine it being similar to meth injection.

 

Re: over 400 HP. I have read on here many times that if you want to make over 400 HP with a 3.8, you'd be best putting in forged internals. the 3.8 tends to implode without that on HP figures over 400 HP.

 

how much for the crank. Compression either 10:1 or 11.5:1

 

Good luck getting aftermarket internals for the BK2. Because it's direct injected, the piston face is shaped differently.
People say you can use aftermarket BK1 internals, but IIRC those people are also running a turbo. Doing this will lower your compression, which is more ideal for a turbo setup.

 

I cover everything for the 3.8's to include both the BK1 and BK2 so not hard to get at all for me.

 

Rods are available. HC pistons are only custom made. Must be expensive due to the pockets for DI. I did notice the stock ring lands are hardened or anodized. This helps for strength.

 

anodizing, only helps with surface wear.
The process actually opens up the pores, then heated to allow pigment to get captured in the pores as it cools. So, more porous.
Maybe beneficial to holding on to oil, but not for strength.

Hardening actually makes it more brittle.
What I mean is... using a drill bit for example, it's usually made of tool steel which is hardened. It a limited amount of flex before it breaks.
If you take a nail the same size, and bend it, it will bend instead. BUT if you bend it back and forth in the same area, it will eventually shear/break off. That is called work hardening.

Basically hardening will make the part shear/breaking, instead of bending/flexing, BUT will increase the amount of force needed to get to that point.

 

If your going to "build " the low end, do it totally. Especially for forced induction I have plans to do just that. It wil involve re-sleeving with 55 psi proof sleeves. Then you can choose your aftermarket pistons at will.

PS a basic Tkits build at 7 psi yields 525 at the crank, most dyno d are seeing 440's whp. They are out there quite a few. Mine has alot of extra variables and dyno'd 474 at 7.5 psi.

Recently I did porting polishing/a riser with 6 meth injectors and a monster straight 4.5 inch exhaust. I have been seeing 10.5psi !!!!!, and she is solid.
**(I do plan on re-adjusting my wastegate LOL !!! My tune in the ECM was for max 8.5, so all this "other" stuff is from fueling/IM/Exhaust/CERMA.nano.

 

Im wondering if the Stock rods are week or just too much compression.

 

I know for that the BK1 2.0 had "powered metal" connecting rods. It's a sintered metal process. Basically powered metal pressed into a form, heated, cooled, and heated again at a lower point to allow a lower melting point metal to be sucked up by the piece like a sponge. Then finally machined.
Wouldn't surprise me that the BK1 3.8 conrods were made the same way.

There was speculation that the BK2 connecting rods where forged. Not sure if it was proven. I assume they are for the 3.8 (but speculate on the quality of forging) because of the higher compression and direct injection.

EDIT: on the topic of ethanol, Heet (I think the yellow bottle) is 99% methanol. I know at krogers gas stations (colder regions) they add a bottle directly into the fuel pump, if you opt for it. Not sure if it's the red bottle (basically something like 95% rubbing alcohol) or the yellow bottle

 

As Gencoupe alluded to, the weakness in the BK2 3.8 are the rings.High compression is awesome, response, efficiency. they just make for a nasty environment in the cylinder. Add to that boost and you have quite the wasteland. Not for the pumpgas at heart.

Fueling, fueling my bro, that is your salvation.Along with indestructable NGK race plugs.