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MBC and autocross - DLC?
Posted: Fri Jan 24, 2003 3:45 pm
by boostjunkie
I'm used to autocrossing in a N/A car . . . and since the autocross season around here is starting up soon (~April) I was wondering how you maintain smooth transitions for braking to acceleration in a turn. That's one of the reasons why I'm making sure the PTFB problem is non-existant on my car, since I have a feeling I'll be in that area alot . . .
DLC, I know you ran a Hallman MBC on you car before the AVC-R . . . how did you get around the off-boost to on-boost situations while in a long sweeper?
Posted: Fri Jan 24, 2003 7:19 pm
by DLC
I only autocrossed once or twice with the MBC, but keeping in boost while in the turns is kinda tricky, and i never did master it, though i can offer you one simple bit of advice that will make you faster, if you actually use it:
Left Foot Braking.
If your brakes are good enough, you can actually modulate the engine speed through turns and in corners by both getting into the gas and braking, to load the engine and get the boost up. By the time you get to where you can let loose, the turbo is already spooled up and you shoot off like a rocket. I got this to work a few times, but got out of the practice as the tranny got worse off (4EAT).
This does apply to both automatic and manual transmissions, but it's considerably easier to do in a 4EAT.
A free flowing intake and exhaust also help the turbo get going faster, quicker...
Posted: Fri Jan 24, 2003 8:35 pm
by boostjunkie
Hmmmm, I'll have to try that left foot braking technique. Should be fine with a 5sp since you never drop outta 2nd gear anyway. Exhaust . . . In all honesty, would a 3" turboback really spool the turbo quicker than what I've got (3"DP, 2.5" turboback and hi-flow cat)?
Posted: Sun Jan 26, 2003 7:58 pm
by inzomniac
The bigger the pipe.. the less torque you will have... simple as that. And since auto-x focuses mainly on low end torque, you wont want to go any bigger.
Posted: Sun Jan 26, 2003 8:56 pm
by DLC
For the stock turbo, 2.5" is just fine.
We've been all over this "big pipe, low torque" thing a billion times. Fact is, with an 8.0:1 compression ratio, any time you're not in boost you're going to have the torque of a Metro.
Dave
Posted: Mon Jan 27, 2003 4:03 pm
by boostjunkie
Turbo's not stock. It's a TD05-16G.
Posted: Mon Jan 27, 2003 8:57 pm
by DLC
Hmm, then you might actually benefit from a larger 3", but in talking to a few people who regularly install exhausts, 3" is very tricky to do right under our cars.
If you can find any info on exhaust sizes for that turbo, say from a DSM or whatever, you might be able to judge whether or not anything larger would do much good.
Dave