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| $100 brake upgrade (Page 4/43) |
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fierogt88
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APR 04, 02:17 PM
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| quote | | Originally posted by Blacktree: I'm not neglecting anything. As I already stated, the bigger booster will take longer to pressurize. Do you have an air compressor? If you use it to fill a 10 gallon tank, does the pressure somehow end up being lesser than a 2 gallon tank? If the compressor is capable of 100PSI, it will fill both tanks to 100PSI. The difference is time. |
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You are neglecting that there is a limiter of the vacuum somewhere in the system, and it could be drastically different between a 2.8 and a 4.3. When you look at a compressor that is "capable of 100 PSI", you are looking at the rating of the TANK not the compressor. So yes time is the factor, but if the check valve in the s10 booster maintains half the vacuum that the fiero check valve does, then you have half the assist. And this would be perfectly acceptable if, say, the s10 uses twice the mechanical leverage at the pedal...
Edit: I can't believe I wasted my 1000th post on this... lol
[This message has been edited by fierogt88 (edited 04-04-2006).]
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Blacktree
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APR 04, 02:25 PM
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I'm not going to waste any more time with this useless diatribe. Phil, I'd like to offer my apologies for participating in the degeneration of your nice thread.
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fierogt88
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APR 04, 02:32 PM
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And this is why I don't come here much anymore.
Anytime you actually try to talk facts, science, and logic with the "dur, uh yeah, well think about it" types, they get all pissy...Last I checked it was friendly discussion about the real -->TECHNICAL <-- situation in the tech section with tech type people but somebody had to get sand in their vagina...
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Pyrthian
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APR 04, 02:45 PM
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ALL engines run at approx the same vacuum.
vacuum is determined by cam profile, not engine displacement.
a 1.6L has basicly the same vacuum as a 6.9L
now, the 1.6 wont have as much volume as the 6.9, but the vacuum will be the same.
and both will give brake boost almost instantly
so a 1.6L chevette can use a 6.9L suburban booster is they wanted effortless brakes
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tjm4fun
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APR 04, 02:51 PM
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just an observation.
Phil tried this and it worked. if another tries it and it works, it would be confrimation.speculating on theory without all the proper data is usless.
The 2 issues i see are: recovery time for the vacuum when the volume is increased, and is the vacuum supplied sufficient.
if it works the answer is a qualified yes. would need actual before and after data to evaluate this properly, then we would need
a qualified engineer in gas systems to review it. I don;t do gas systems. I do EE stuff. so let's see where our engineers in gas syetems would say.
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fierogt88
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APR 04, 03:03 PM
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| quote | | Originally posted by Pyrthian: ALL engines run at approx the same vacuum.
vacuum is determined by cam profile, not engine displacement.
a 1.6L has basicly the same vacuum as a 6.9L
now, the 1.6 wont have as much volume as the 6.9, but the vacuum will be the same.
and both will give brake boost almost instantly
so a 1.6L chevette can use a 6.9L suburban booster is they wanted effortless brakes |
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Well that's a pretty big statement, that ALL engines run at the same vacuum...
I know my 3800 supercharged does not... And I know lloyde commonly sets up his swaps for full time boost... I don't know how he pulls that off... But maybe all normally aspirated do? That's a possibility... Do you have any links or sources for that claim? And if a chevette could use a suburbans booster... why wouldn't it?
Heck, why should we stop at an s10 booster? Lets just run out and get one off of a Ford Excursion!
Oh yeah, that little thing that I brought up about tuning it (the diaphram size, the check valve, and maintained vacuum) to the mechanical leverage in the original vehicle... And on the volume of the booster...
So we're going to a XX% larger booster...
With a 50% smaller engine to fill it with...
Well, that's gonna be significantly over a 50% increase in vacuum charging rate...
Does that matter? it might.
We'd have to know exactly how much bigger the diaphragm is, how much more volume, the rate of vacuum for both engines... Seriously though, to satisfy me all I'd need was a vacuum gauage hooked up to the constant vacuum side of the booster (after the check valve) and make sure that at least as much vacuum was maintained during driving conditions. That's not so hard... So, when Phil comes in, 2 questions...
1. What is the exact diameters of the 2 booster pumps?
2. Any chance you could hook up a vacuum guage to the constant vacuum side of the booster? I'd be willing to do it for the stock one for comparison purposes...
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Pyrthian
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APR 04, 03:26 PM
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| quote | | Originally posted by fierogt88:
Well that's a pretty big statement, that ALL engines run at the same vacuum...
I know my 3800 supercharged does not... And I know lloyde commonly sets up his swaps for full time boost... I don't know how he pulls that off...
But maybe all normally aspirated do? That's a possibility... Do you have any links or sources for that claim? And if a chevette could use a suburbans booster... why wouldn't it?
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yes, boost does change things 
no, no links for that claim.
but, I think 12-14 PSI is standard vacuum for average street cars
and, some brake effort is a good thing, to prevent overbraking.
gotta give the person behind the wheel some pedal pressure, to have a "feel" for the brakes
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Phil
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APR 04, 04:06 PM
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With the throttle plate closed my engine pulls about 18"Hg- Now think about this- Once the vac side of the booster is evacuated the black check valve keeps it evacuated in fact you could even pull off the hose and you will still have power assist for about 2 or 3 pedal applications. Usually when you step on the brakes you take your foot off the gas and then you get max vac. I have put about 4000 miles on this setup without any noticable difference except that my brakes work much much better. The first booster I had did have a vac leak in it and whenever I stepped on the brakes I did get a slight RPM increase but a reman booster fixed that right up. As for the length of the push rod just measure the distance of the stock Fiero from the back of the bracket to the center of the attachment hole. I think you have to add about 2 1/8 " but meqasure to be sure. If I step on my brakes 3-5 times with the engine off (gets rid of any vac reserve in the booster) and then start the car I have full power assist again in under 2 sec. Ther is someone on the forum ( I forget who) who works in brake booster design and he had no objections to this mod . I used to be an engineer and I'll say that actual data is light years ahead of imperical data. According to the "experts" a bumblebee shouldn't be able to fly either.
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Phil
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APR 04, 04:12 PM
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| quote | | Originally posted by fierogt88:
Well that's a pretty big statement, that ALL engines run at the same vacuum...
I know my 3800 supercharged does not... And I know lloyde commonly sets up his swaps for full time boost... I don't know how he pulls that off...
But maybe all normally aspirated do? That's a possibility... Do you have any links or sources for that claim? |
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On a S/C 3800 ( that's what I have) the vac for your brakes is taken from infront on the S/C so boost pressure has no effect BTW to set for boost all the time just disable the boost bypass valve.
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Quickster
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APR 04, 04:29 PM
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But I have a revelant question.........Does replacing the Master Cylinder with a Bigger one have an affect on the pedal? I replaced my M/C with a Bigbore and the brakes haven't been the same since! Now,...if I replaced the Booster with the aforementioned S-10 option,...would that help my "soft Pedal" problem?
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