Sinful7

I'm thinking about building a custom twin-turbo setup for my olds, and the roadblock that I've hit is with the fuel system. I'd like to stay as close to the stock longblock as possible. We're talking about the infamous central-port injected 90 deg. GM V6. I'm currently trying to devise a Multi-port fuel injection scheme that will replace the entire intake manifold and plenum, while retaining the factory throttle body, or a standard GM equivalent.



I was thinking about a single TB with split intake tracts leading to a pair of collectors (one for each bank). Each collector would have 3 port dump tubes, and one 800c injector per cyl.

Dramon_Killer

gn swap!



- Hand

Sinful7

Not a bad idea. I need to look into how Gn's are setup, but they're prolly TBI..

TYSON

Nope.





Maybe check out a newer version of the 4.3? they did go to MPI eventually, and you likely could nab that for pretty cheap.

Sinful7

They did, in fact go MPI, but it's CMPI - Still uses a central feed to operate six poppet valves. There is an upgraded unit that uses individual tiny injectors, it's an aftermarket item but from what I understand, it works. My concern there is that I'll never be able to get the most from the injectors, I'm sure their flow volume is not very large. Besides, then I'd be running an OBD-II compliant engine, along with it's ECU, and my OBD-I ECU for the body controls (Yes, it's integrated), as well as an aftermarket ECU for fuel and timing control with the turbochargers.. If I could fab some intake manifolds for the stock block, I could potentially use only the aftermarket fuel ECU and the stock ecu together. Less systems to fail.



Are you saying that a CPI-MPFI isn't possible? Or that the GN doesn't have TBI?

TYSON

Pretty sure it's multi-port. Definately not a throttle body injection. They're throttle body is horizontal on top of the manifold.

nismo convert

a lot of the nissan guys were doing a similar swap on the old school sentras, they said the wiring was a ****, maybe go standalone in the bravada?

Sinful7

Yeah, I'm thinking of a TEC-3 or MoTec system, but I'm mostly concerned about the feasability of the 90 degree V6 with a pair of seperate intake plenums for each cylinder bank.

Dramon_Killer

Why spend so much money on the bravada in the first place?

Sinful7

I just spent a few thou repairing it. Now the entire suspension is new, the fuel and ignition systems are new.. The interior and body are in good shape, so why not?