Why does the 85.5 SVO make 40hp more than the 84-85 models?

B0B N Weave · 10-20-2009

I keep seeing that the 85.5 made 205hp. A 40hp increase is alot.
What did they do to increase the power? Is it easy to just do what they did to the 85.5 to my 84 and get the same results?

TOM RENZO · 10-20-2009

It doesn't It makes 30 more HP. The early engine ran 30 lb injectors and a restrictive intake and only 14 lb of boost. The engine made 175HP and 210 ft/lb of torque. The late engine has 35 lb injectors (brown tops) and the boost was upped to 16 psi. The A/R ratio was speed up from .63-.48 This speed up spool time. The intake was also redesigned to flow better. The most powerful svo was 205HP at 248 ft/lbs of torque. That would be the difference of exactly 30 HP and 38 ft/lb of torque between the years. Hope this helps clear up the mistery. TOM RENZO

B0B N Weave · 10-20-2009

Thanks Tom. That pretty much covers it

NavySVO · 10-21-2009

Tom was close enough so I will not nit-pick.

The most important thing left out is the EEC change for those 2 models. It has a more agressive tune with regards to the fuel and timing mapping.

84 had TE and ZB1 EECs
85 had PJ EEC
85.5 and 86 had PE EEC

B0B N Weave · 10-21-2009

Quote:

Originally Posted by NavySVO

Tom was close enough so I will not nit-pick.

The most important thing left out is the EEC change for those 2 models. It has a more agressive tune with regards to the fuel and timing mapping.

84 had TE and ZB1 EECs
85 had PJ EEC
85.5 and 86 had PE EEC

So is it possible to just swap out EECs. My SVO right now will bring the boost gauge up to 18 psi and hold it. I wish used cars could speak.

TOM RENZO · 10-21-2009

Yes the tune is more agressive and the newer computer is tuned around those BROWN TOP. I also think the timing is more agressive and comes in earlier. Been a long time since i plotted those ECM'S Thanks Kurt i was going to add that but its the age thing. Thanks for posting that. TOM.

mg man 75 · 10-21-2009

Thanks all. Learn something everyday Maurice

NavySVO · 10-22-2009

Ok, just to elaborate a bit;

You can plug the PE right into any SVO harness without repinning.

Yes, it is programmed for 35# injectors.

The intake really is only different in the torque catagory. I have seen people with an inline intake make the same HP numbers as a square intake, but actually make higher numbers in torque due to the way the intake's runners are designed. Food for thought.

The turbo to select (.48 or .60 turbine A/R) will only determine how you want the car to run with regards to power vs RPM. The lower the A/R, the quicker the spool with power in the power RPM ranges. If you are going to be running the car in higher RPM bands, then a larger A/R is desired. The lower A/R turbine will actually impede higher RPM ranges due to cylinder backpressure.
Most AutoX peeps like the lower A/R, and road racers and drag racers like larger A/R turbos.