MazdaManiac

iTrader: (3)

lol.
No, its just arcane and has some concepts crossed up in tricky ways.

Kane

iTrader: (1)

YOU ARE!!!!

Yeah........ so there!!!

olddragger

iTrader: (3)

one thing that needs to be mention is that with the s.c car you can cruise and not be in boost. that means 22-23 miles per gallon on the hwy. with a turbo you are in boost all the time so gas mileage suffers..
s.c cars idle faster, s.c. car have a flash available for the oem pcm, there is a cobb unit so custom tuning can be done on both.
pluses and minuses with each setup.
you choose.
OD

mysql

You misunderstand the fundamentals!

With a turbo you are in boost only when load is high enough. Which means out of boost you have nothing. With a SC you always have a mechanical belt being spun.

In fact, last I heard, the Pettit SC generates boost at idle, which is why they had issues and ended up increasing idle rpm.


Any reflash can increase idle. Mine is set for 900 rpm.

olddragger

iTrader: (3)

i thought turbo motors were under boost all the time?
So you can pull a vacuum at cruise? Do you set your waste gate for that? Then load(guess a map?reading) signals the waste gate to kick the boost in,limited by the boost controller?
See --that is too dang complicated for this old man--i would screw that all up in one day. Same reason I didnt buy coilovers--i would mess with them too much.
olddragger

mysql

you don't set anything up for it. At cruise the airflow is not enough to spin up the turbo to force air into the engine.

The left gauge in this video is boost. At 9 o'clock is 0 psi. Watch when it goes above that:

http://www.youtube.com/watch?v=pUoA0RuD7Pk

MazdaManiac

iTrader: (3)

Wow. You need to step away from the keyboard.

BTW - Most of the Petit SC cars that I've had contact with get terrible gas mileage, so consider yourself lucky.

Brettus

iTrader: (2)

yeah /\ what they said
Also iv'e noticed that i have more power than N/A even before i get into boost something to do with the reduction of vacuum at light loads i guess

mysql

the turbo is spinning because it sits in the exhaust, so it will push a small amount of air as the exhaust flows through it. It won't give you positive pressure till you increase the load though. This is still completely different than what dragger said about turbos always running in boost. That statement is patently false.

However that slight amount of air does increase power slightly. If you had the synchronic BOV and had it venting instead of recirculating (no anti stall valve), you would completely remove this gain because air excapes out the bov when not in boost instead of going into the engine.

It's still "free" power too, you're not dragging down the engine with belts and spinning hardware.

Brettus

iTrader: (2)

/\ that's what i thought - heh

these turbos are pretty good eh ?

mysql

yeah, you should get better fuel economy with a turbo. best of all, you don't need 1000 rpm idle either (As if higher idle increases fuel economy) :P

Brettus

iTrader: (2)

Weight diff is pretty negligable - a top mount system might take a little away from the handling . A bottom mount probably not . Power will change the characteristics on the track for sure .

Kane

iTrader: (1)

A turbo - like greddy is not much weight at all; maybe 20 pounds more than stock.... now if you were going with some huge manifold and turbo; mounted really high it might matter.

A SC is high so that is bad - but I cannot imagine the weight of it is very much at all.

Kane

iTrader: (1)

It is both; inside the wheels (like the motor and gas tank) +1; low on the car +1; unsprung weight - 1; higher than the normal center of gravity - 1;

Of course any weight added is bad - but adding a few pounds to double your power is a trade most will make.... if it is a big deal; go on a diet.

mysql

Adding a turbo will decrease your mpg if you USE the turbo. However, in daily driving, even if you boost frequently (every stop light and to get around cars), your mpg shouldn't decrease more than 1-2 mpg. The reason for that is while you are increasing air (and fuel) during boosting, you don't accelerate for as long as if you were stock since you make more power. And if you aren't boosting, your fuel economy should remain about where it was before going turbo.

Blackout04RX

articles about forced induction are a waste if he doesnt even understand the real meaning of torque and HP. he needs to go back, learn what they really are, and how they effect driving, and only then would i suggest even glancing at the FI posts on here. I know alot about engines, but a few of the posts can be a little hard to read, too technical for a casual reader.

olddragger

iTrader: (3)

thanks for the feedback guys--learn everyday. Makes sense that the turbo is not boosting at cruise--kinda like an in balance thing. Appreciate that.
Obviously I dont know a lot about turbos, but am willing and eager to learn all I can as the oppitunity arises.
back to the oridginal ?
Yes it does change the way the car handles--but it is not a weight thing. Its a power thing. Power on tap allows you do do more with the car during cornering etc but at the same time it makes the car harder to drive. Now you can easily put TOO much power down were as before you usually had a little warning before you realized that to much power was being used. So throttle sensitivity increases substanually.
OD

mysql

biggest change over stock is that with stock, you can almost always floor it (WOT) and just sit with the peddle to the ground. With FI you are more likely to only give it partial throttle unless you really want to accelerate.