Gillis valve installation

[WaltM]

I guess the bottom line revolves around the Gillis valve and how disappointed I am on it's promise to deliver a better performing vehicle. All I'm trying to do is improve all around performance; so far, this is has not added anything toward this goal.

Everybody rants and raves about these things, but my experience has not been positive. I just may go back to the stock BCS.

[SVOeric]

The boost controler itself isn't a complicated part. If you set it at the exact same boost level as the stock boost controler, performance should be identical.

If you have turned the boost up, and are having problems, you need to start looking at fuel octane, ignition parts, and such, to find why it is running worse with more boost. -- the controler itself is not the cause of this.

[AT6svo]

Even though you have the Gillis valve installed you -DO- have the premuim switch set in the premium position right?

If not, the timing will not advance to its max capability to support the added boost level.

If that was stating the obvious, I apologize.

[WaltM]

Not a bad question to ask. I've been guilty of missing the obvious more than once.

I think I have all my bases covered. On the advice of the instructions, I did leave the electrical connections to the BCS attached. I am running Amoco or Sunoco premium and the premium switch is lit.

Maybe I have some bad gas? Maybe there's something wrong with the switch?

Who knows?

[Tooltime]

I think my situation might be the fact that I've got old gas in the tank, plus I still have the stock fuel pump and who knows how old the filter is. The reason I brought up the question in the first place is to find out in fact once the boost is raised would it put a strain on the fuel pump.

[AT6svo]

Originally posted by WaltM

Maybe I have some bad gas? Maybe there's something wrong with the switch?

Who knows?

Bad gas? not likely. Defective switch, its possible. On the 85.5/86's, there is a vacuum operated soleniod/relay that senses boost pressure that increases the voltage to the fuel pump. If the pump is not recieving the extra voltage, it will not be able to supply more fuel req'd at the high boost levels...

The octane switch and fuel pump relay can be "tricked" or bypassed to hot wire them into premium mode and under boost conditions respectively.

Tooltime - strain is never placed on a fuel pump, it simply will not be able to achieve the fuel rate and pressure levels, UNLESS there is blockage in the sending/return lines preventing flow OR if there is under or over volatage to the pump itself.

[GAboySVO]

The gillis boost valve will allow more pressure to build and potentially more power produced, but power to the fly wheel is based on how much air you can pump through the engine. If you have some restictions to flow in the exhaust side then you will not see much extra oomph! with increased boost.

Increasing the boost pressure also adds more heat to the air charge. A hotter air charge is more prone to detonation. The knock sensor would pick this up and retard the timing. Retarding the timing causes a loss of power / torque while advancing can add power and torque. As with most things there are trade offs that is why the EEC controls the timing based on engine sensor inputs and advances or retards the timing according to prevent the engine from self destruction.

[Tooltime]

Good stuff thanks guys.

[8T6 SVO]

One of the first things that I did with my low mile car was put a bleeder type boost controller on and turned up the boost (+2.5 pounds). Mind you this is a completely stock/original car with timing/everything set stock.

The boost controller is very effective.

I did feel a big difference, but not until I put some race gas into the tank. As you are describing "But it seems to be missing something power wise", leads me to believe that as extra boost, heat, and pressure are applied to the engine, the engine responds ( because it wasn't designed specifically to use 17-18 lb of boost) by detonation or pinging. In response to the detonation or pinging, the computer retards the timing as a protective measure which give you the "seems to be missing something power wise" feeling. I used race gas and this feeling went away. Try it - 96-100 octane and tell us how it runs.

This may not be your problem, but might be one way of narrowing the problem down.

8T6

[ConradStang]

Originally posted by 8T6 SVO
Try it - 96-100 octane and tell us how it runs.

This may not be your problem, but might be one way of narrowing the problem down.

8T6

So how did it turn out? I am very curious, being a hopeful "soon to be" SVO owner.

[Tooltime]

Originally posted by ConradStang
So how did it turn out? I am very curious, being a hopeful "soon to be" SVO owner.

Well I have'nt registered the car yet, so I don't want to drive it too far from home. I could always get off my butt and go fill up my 5 gal. container with some race gas, but it's supposed to snow again tonight.

[WaltM]

Well I put in 3/4 of a tank of 94 octane along w/an octane booster. By my math, the current rating in my tank is about 94.2.
This has produced a noticable difference especially during idle and all around drivability.

But after all the input and research, I've decided to go back to ground zero and recheck everything; timing vacume etc.

I'm also a little concerned about using the octane booster. After all, shouldnt the car run this way on 93? Am I covering up a problem, or helping an older engine run better.

[8T6 SVO]

Originally posted by WaltM
I'm also a little concerned about using the octane booster. After all, shouldnt the car run this way on 93? Am I covering up a problem, or helping an older engine run better.

It should run o.k. on 91/92/93 octane - what ever pump gas you can get. The SVO was desighed to run 15 lb boost in the "premium" mode while using this gas.

However, if you turn up the boost, the engine will have a harder time running "good" with 91/92 octane pump gas. I have found that while turning up the boost (or even leaving it at a stock 15 lb) the car runs A LOT better with higher octane fuels.

You are not covering any problem by using higher octane fuel - the engine "likes it".

[AT6svo]

We should not forget another important pat of the equation. -Air temperature & density.

Running an FMIC inplace of the stock inter-heater (I mean intercooler) will also allow higher boost levels due to decreased air temperature, which results in reduced detonation. Allowing for increased boost levels w/o the requirement of higher octane (93+).

[TurboPete]

Walt. I may have missed it but if you are still running a stock fuel pump you might want to run fuel system diagnostics just to make sure you have enough at elevated boost. See http://www.turbotbird.com/techinfo/F...iagnostics.htm