But again, we need details. The is your brakes, after all.

I wasn't talking about a vacuum drop. I was talking about more volume causes less vacuum given the same source. That is a fact. Deal with it. To get around this, the source of the vacuum (the engine) has got to work harder. And as far as the vacuum cleaner comparison, I'm sorry but there is still a time difference between when the vacuum cleaner registers vacuum in a pop bottle and when a vacuum cleaner registers vacuum in a tanker truck.

We already have the answer to my first question: does a bigger brake booster automatically mean more brake assist?
The answer is No, not absolutely. In the case of the s10, it may provide more brake assist - but the bigger size alone does not automatically guarantee it.

So we go back to my second question: can the stock engine supply the vacuum necessary?
Well, if this came off a 2.8 s10 I wouldn't have any problems with it, but I'm guessing this came off a 4.3 s10. The 4.3 is significantly larger - 1.5 liters larger. Over 50% bigger. Now, I'm no expert on how engines produce vacuum, but it sure raises a question, in my mind anyway, about a whether a brake booster designed to be supplied by a much larger engine will be satisfied by the much smaller 2.8.

And now I've got a new question: How is the vacuum regulated in the brake booster?
Since the engine is almost constantly producing vacuum, there has to be a limiter for how much vacuum is produced. My assumption at this point is that there is some kind of pressure valve in the booster assembly. Is the valve the same size? Does it provide the same air flow? Is it tuned to peak the booster at the same amount of vacuum? Or more vacuum? Or less? Is it even inside the brake booster?

And here is another one: Is the booster appropriately sized for the mechanical leverage of the fiero setup?
Right off the bat I know absolutetly that there is a greater distance between the booster and pedal in an s10 than there is in a fiero. This means there is a lot more opportunity for the s10 to get brake assist from mechanical leverage of the pedal linkage. Quite simply, if the s10 uses twice the mechanical leverage, the booster may be tuned for HALF of the total brake assist power. That would not be a good thing....

Again, I'm not bashing the mod. Obviously Phil is reporting good results so I'm sure that the answers to these questions, once answered, will prove mathematically that it's an improvement. But if you think I'm gonna trust my brakes to "seat of the pants" you've got another think coming. I'm just saying that there are a lot of VALID questions that have to be answered before we all run out and slap them on.

And now that I think more about it, this flies in the face of the formula posted above.

Increasing area decreases force, according to the formula. The only way around that is to increase vacuum...

But sorry, all my points are valid. The brake system in any given vehicle has a lot of components in it that all work together to correctly give the right amount of brake force according to known mathematical principles. The questions are there, and need to be answered before anybody starts proclaiming it as a safe upgrade for the masses. I'm sure that once we know the answers, it will all fall into place, but my questions are unargueably valid. So if anybody needs to calm down, I say it's the "defenders of the holy" that are here trying to use the "well duh bigger is better" method of analysis.

EDIT: Oh, and once we start seeing actual numbers, it's quite possible that this will actually work better with a bigger s10 master cylinder. Again, this has great potential but lets see some real math here...

Actually, since it is assist, it is not the same at the big bore MC problem...I digress,

If F=P/A that means that if you increase A you need less P to do the same amount of F right? The booster is adding to the P that you apply.
So doesn't that mean it takes less pressure (from your foot + booster) to make the same amount of force (on the brakes)? So in theory with more P AND more A you get much more F.

The reason this doesn't work with the MC is the P is working against you....instead of assisting you. I hope this makes some sence.

Best regards,

~Shane

No.

Edit: The formula is wrong, so incorrect info removed...