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Positive Boost Limit Braking
(12 posts, started )
Positive Boost Limit Braking
ok i am awear that this susjestion is not very important but a valid one at that. In most forced induction cars positive boost dosent allow the vacume brake systems to work corectly and you lose braking by a small ammount,eg more time on positive boost = less vacume = less braking assitance.

Now im well awear lfs can not make the OUR pedals harder or softer but they can make it not brake as hard when poisitve pressure is held for long periods of time

PS. i just enjoy seeing how bad the vacume assited braking is in differnt turbo'ed cars IRL
Maybe all the turbocharged vehicles in LFS have electric vacuum pumps for the brake booster.
#3 - Osco
do you brake while still on the throttle then? trailbraking doesn't require that much of brake pressure to validate this and I'm sure there's checkvalves in the vacuumline from the brakebooster to the intake manifold which do not allow positive pressure to the brakebooster
Quote from Osco :do you brake while still on the throttle then?

No, but you don't get any brake assistance immediately after the engine returns to vacuum. In my car, if I pump my brake pedal with the car off until there's no vacuum left, then it gets really hard to push. When I turn the car back on, the engine idling creates vacuum. But if I push my foot down on the pedal, it is still difficult to push. It takes a few seconds to get vacuum in the actual brake booster. Of course, it is very possible that the check valve in my brake booster doesn't open fully or something. But going from engine off (no vacuum) to vacuum is basically the same as a turbocharged vehicle going from boost to vacuum.
Quote from wheel4hummer :No, but you don't get any brake assistance immediately after the engine returns to vacuum. In my car, if I pump my brake pedal with the car off until there's no vacuum left, then it gets really hard to push. When I turn the car back on, the engine idling creates vacuum. But if I push my foot down on the pedal, it is still difficult to push. It takes a few seconds to get vacuum in the actual brake booster. Of course, it is very possible that the check valve in my brake booster doesn't open fully or something. But going from engine off (no vacuum) to vacuum is basically the same as a turbocharged vehicle going from boost to vacuum.

Your brake booster or the check valve isn't working properly.

I dunno how big the effect can be on turbo'ed cars, but I can't believe there would be a good way of simulating this in LFS, or in any game for that matter.
At least not before we get FFB pedals on our steering wheel sets.

The problem is that if you don't feel the "pressure" from your pedal, but brake power keeps changing from situation to situation, it would be almost impossible to have a good control over the brakes and would feel very annoying when the brakes do their own stuff.
yer it like i said u the game cant change the brake pressure of our pedals but yer it was only a small susjestion and not very important atm

and i beleave most turboed race cars have a one way solnoid setup to stop this from happening to the extent road cars do it
Quote from MAD3.0LT :and i beleave most turboed race cars have a one way solnoid setup to stop this from happening to the extent road cars do it

Well, the brake booster does have a check valve with a spring which only allows air to be sucked out of the brake booster. So when there is boost, it's not like the boost is pressing against the brake pedal.
Guess what. Ever think that the brake booster may be hydraulic? Besides, I have never heard of any problems with boosted cars having brake problems, if you do then you have that vac line hooked up to the wrong place pal.

A lot of cars have Hydraulic boosters now days. Never seen an electric booster though.
#9 - bbman
I too can't think of a reason a car manufacturer would make such a security oversight... Badly tuned ricer-cars on the other hand...
Quote from skstibi :Guess what. Ever think that the brake booster may be hydraulic? Besides, I have never heard of any problems with boosted cars having brake problems, if you do then you have that vac line hooked up to the wrong place pal.

A lot of cars have Hydraulic boosters now days. Never seen an electric booster though.

lol u oviously havent driven many superchagred/turbo'ed cars mate :P

im not talking about holding positive pressure for 10/20 even 70 seconds affecting it that badly that u cant brake. every turboed car i have driven if you hold positive pressure for about 40/60 seconds you can JUST feel a slightly harder pedal but if you trail brake and never let the car get vacume the brake booster lose's pressure due to braking and by the next corner you barely have any vacume left to assit in your braking.
With the throttle closed the engines generate manifold depression, and that's plenty for providing sufficient servo assistance (I find the term brake booster a misnomer - it doesn't boost your brakes at all).

If a riced up car suffers from a lack of manifold depression then it can easily be increasing using a vacuum pump off a diesel engine (no throttle, so negligable manifold depression).
Quote from MAD3.0LT :lol u oviously havent driven many superchagred/turbo'ed cars mate :P

im not talking about holding positive pressure for 10/20 even 70 seconds affecting it that badly that u cant brake. every turboed car i have driven if you hold positive pressure for about 40/60 seconds you can JUST feel a slightly harder pedal but if you trail brake and never let the car get vacume the brake booster lose's pressure due to braking and by the next corner you barely have any vacume left to assit in your braking.

I have driven enough to know that my face still gets peeled off with the same brake pressure. Driving along going up a long straight up hill section of road for about 15 minutes steady and not letting off, I still don't have any issue with brakes. Just one time of positive boost braking will not make that much of a difference for the next time you brake, it will if you keep it up for a couple more times.

unless you are on an oval or some strange track where you don't need to let off for a few corners that you for some reason brake for (ok, I can see this if you have a corner that you just want to slow down for a little but keep up the boost) I can't see you doing that more than 1-2 times before having to let off again for another corner. It usually takes 3-4 times for me to hit the brakes hard before my booster looses vacuum when I have no vacuum source.

Positive Boost Limit Braking
(12 posts, started )
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