I need some opinions please. I have just finished a complete swap from a 305TBI to all new 350TPI in my '92 RS. I currently have GM TPI ecm harness and Accel-DFI "adapter harness" which will allow me to plug in the DFI and go.

Should I spend $500-$600 on the DFI computer or just buy/program a custom chip? It sounds silly, but The DFI computer is not cheap in my mind! My current mods are not anything radical, but an ATI intercooled supercharger is coming next summer. Any thoughts?

------------------
'92 RS, ZZ4 10:1 350, Edelbrock 6085 heads, Crane 208/214* 467/482" 112* cam, GM/LT4 1.6 roller rockers, Edelbrock Hi-Flow TPI base, runners & 52mm TB, SLP/Jet-Hot 1-5/8" headers, Catco 3" cat, Flowmaster 3" catback, Hughes 2500 stall converter, stock 700R4, 1LE driveshaft, Auburn Pro posi w/3.42, 17x9" SS rims w/BFG tires, Medium Quasar Blue w/white SS stripes, 48,000 miles....

 

For what it's worth the DFI is very adaptable for NOS or superchargers. For NOS it has a built in retard control which you can have automatically activated with the NOS switch. For a supercharger you simply replace the 1bar Map sensor with a 2bar (or 3bar for over 15psi boost) re-program and go. I have an Accel DFI in my '86 camaro and I didn't find it hard to tune, like some others might say. It took a couple of months to get it just right, but I assume the same is true about PROM burning.

Also, you can tune it (DFI) on the fly with a laptop without needing to remove a PROM, burn it, and replace. You can see your changes take effect instantly and Calmap does have data logging features to collect information such as O2 voltage, TPS voltage etc...

 

Hey scott I have almost the same setup as you do and am wondering the same questions also, what is the stock throttle body on a 91 Z-28 is it a 52mm. Let me know if you get any answers

 

You can support 400HP easily with a stock ecm, questions about DIF belong somewhere else.
Using a syclone chip and ecm, with handle a supercharger.

 

This past weekend saw lots of DFIs, and others, ya tune on the fly and fly right by optimum.
tune on the fly write no notes, and take 4x as long to dial the car in.

 

PT: stock throttle body is 48mm.
I did the TBI to TPI swap about 3yrs ago. I chose to go with the DFI, believing it to be easier to program and modify than programming chips. There are benifits of going either way. Tunedport350 pretty much summed it up. An arguement against DFI is that it's easier and cheaper to replace the ECM if you stay stock. Good luck either way you go...