[tb30570]

I have two cars right now. One that I wish was a little faster and one that I wish I didn't have to be so careful with the throttle. I'd like to eliminate one of these issues.

My daily driver is a 335xi with a cx racing IC, VRSF 3" Catless Downpipes, a removed clutch orifice and a cobb tuner. It runs 300' in about 5.4s.

My other car is boosted c5 and runs 60' in about 1.7s, 300' in about 4.9s and the 1/4 in about 11.4s. Hook up on a clean/prepared track with <18psi in the tires is way different than hook up on the street with >25psi in the tires. I've switched to running drag radials all the time, but they scare me on corners and don't work well when it's cool outside.

How would you recommend pushing my 335xi harder to shave off at least 1/2 a second to 300' without using additional ethanol in the fuel tank or nitrous oxide? I'm guessing meth/water is part of the equation, but maybe not all of it.

[Chris@BoostConcepts]

Lol.. You don't ask for alot.. .5 by 330 is ALOT to ask for. Obviously 60' is where most of it will be gained. What is your current 60' with the BMW?

More power will help of course but you have pretty much eliminated most options for making more power by octane limiting yourself. You said without additional ethanol in the tank, does this mean you are currently running a mix?

A meth kit will help with IATs and allow some more power, but you are a manual tranny car so you won't want to spray a ton of it to try and add octane. Not smart on a manual car as a missed shift or funky timing issue and small front fire can grenade the intake manifold so to be safe you will want to keep the water meth mix at least 30/70 to avoid that.

Being you are focusing on the first 330' most upgrades like bigger turbos will make this task more difficult as launching them in a manual has drawbacks and being XI you have driveline components to consider.

I would say max out your stock turbos (for the octane you have capped yourself at) with all the latest mods such as Inlets, meth, tune, and then focus on suspension and tires and nailing your launch technique to wittle down your 60'.

[tb30570]

Originally Posted by lcvette

What is your current 60' with the BMW

I've only done 4 runs with my current setup but out of the 4 my best 60' is about 1.82. If I did a few more, I'm guessing I could hit 1.80. If through some magic modification, I dropped it down to 1.7 or lower, would CV shafts start flying apart?

Originally Posted by lcvette

You said without additional ethanol in the tank, does this mean you are currently running a mix?

In the corn belt most gasoline has 10% ethanol. I run 93 octane E10. It's very easy for me to buy where I live though a little tougher on road trips. Sometimes when I travel I fill up on 91 octane because that's all I can find. There are a few placing where I live that sell E85, though they are out of the way for me. On road trips, finding E85 would be a pain in the ass. Also winter mix and summer mix E85 are different and who knows what you are buying in the spring and fall. I'd gladly set up E85 for a car I drove a few times a week. For my daily driver and road trip car, it seems like more pain than it's worth to me.

Originally Posted by lcvette

to be safe you will want to keep the water meth mix at least 30/70 to avoid that.

That's pretty much -30 degree window washer fluid or -20 with a bottle of heat. Is there any reason to go to a trunk mounted kit vs. using the window washer fluid tank if the fluid isn't any more flamable than washer fluid?

Originally Posted by lcvette

the latest mods such as Inlets, meth, tune

What do you mean by inlets? I've seen some adjustable orifices prior to the turbo inlet that maximize air velocity to spool up the turbo faster; then once the turbo is spooled up, the orifice opens up to allow for higher flow rates. Is that what you are talking about?

What about less restrictive exhaust behind the down-pipes? Worth the money?

[Nonecure]

This will not answer your questions, but could help. I am not FBO, just intake and intercooler. I am running the MHD wedge tune with E40. My car is full weight and I am not a drag racer, so my run was just to see what my car can do.

60' = 1.81
330- = 5.21
1/4 = 12.2
MPH = 115.2

So I think you can get there, but without E85 you will need meth. Inlets are the latest thing since the turbos lose flow with stock inlets. I'm thinking about these when I finally install down pipes http://www.vr-speed.com/vrsf-upgrade...i-e90-e92.html

Also if your looking for good 1/4 mile numbers, Wedge is the guy to call.

[tb30570]

Originally Posted by Nonecure

My car is full weight and I am not a drag racer, so my run was just to see what my car can do.

I'm not a drag racer either. I figure if a car is set up to run 330' fast, it's going to be fun to drive on the street. Cars with massive turbos and cams may get great 1/4 mile times, but IMO they aren't good street cars.

[tb30570]

How about quick spool valves? (That's what I was taking about in an earlier post but couldn't remember what it was called)
http://www.suprastore.com/spquspva.html

http://www.e90post.com/forums/showthread.php?t=933244

[csu87]

That wouldn't work with stock turbos and has little affect on big singles.

Inlets, as in full turbo to filter intakes, e85 and a custom tune will get you close. Meth can get you close. You can always go back to a pump gas tune for road trips if you are worried about finding e85

[musc]

Unless you're launching from every stoplight I can't imagine that a good 330' time is going to necessarily correlate to a better streetcar. Just make sure your tune has good part throttle drivability and torque if you are focused on the street. As far as the track goes an Xi with meth or E85 should be able to hit sub 5 though.

[stanlalee]

Whatever you don't have already: Protune, meth, inlets (not going to be a fun install with x-drive), single turbo (about the only way to get over 500whp on pump gas). No real secret here, you have an xi so all your really asking is how to make more power. Too bad ethanol is not an option. Would make things a lot easier/simpler.

[Nismo G]

Any unsprung weight upgrades? Something that is often overlooked. I think rule of thumb is if you reduce unsprung weight by 1 pound it is = to shaving 6 pounds of sprung weight.

Maybe look into some lighter wheels and maybe a set of z4 35is rotors. Each rotor is 2 pounds lighter and i'm sure you can save 2-4 pounds per wheel with a decent set of wheels. So you could reduce 8 pounds of unsprung weight with rotors and another 8-16 pounds of unsprung weight with wheels.

I'm going to work this off of stock numbers. 335xi sedan = 3814 pounds and 300hp. So that means for every 12.71 pounds we remove from the car we get a whopping extra 1HP. So lets say we are able to reduce 20 pounds of unsprung weight 20x6 = 120pounds. 120/12.71 = 9.44 extra ponies.

This should get you to 12.6 @ about 108mph.

Not sure how accurate this really is, but i'm sure there are some engineers on here that can validate and or correct me lol

[tb30570]

Originally Posted by csu87

You can always go back to a pump gas tune for road trips if you are worried about finding e85

So i'd need a summer tune, a winter tune and a road trip tune? What do you do in the spring and fall when you don't know what is coming out of the pump? Do you test the fuel's alcohol % somehow?

[csu87]

Originally Posted by tb30570

So i'd need a summer tune, a winter tune and a road trip tune? What do you do in the spring and fall when you don't know what is coming out of the pump?

I slightly adjust my tune, but i have enough fluff in it in my daily tune to account for a little bit of varience. But keep in mind i run 100%e85. If you are running an e40 or e60 blend, you just adjust your ratios to account for the differences. Then if I'm taking a long trip where i know there won't be e85, i flash back to a 91oct map. Takes about a minute to switch maps onthe MHD.

And yes, i test the fuel to see how much ethanol there is. You can get a cheap tester and do it right at the pump. But i also continuously log to make sure i don't have fueling issues and adjust accordingly

[tb30570]

Originally Posted by csu87

keep in mind i run 100%e85.

Did you replace the fuel pump with a higher flow rate model or install a bop? How much ethanol can the stock pump support...how much with a stock pump plus bop?

[tb30570]

Originally Posted by Nismo G

Any unsprung weight upgrades? Something that is often overlooked. I think rule of thumb is if you reduce unsprung weight by 1 pound it is = to shaving 6 pounds of sprung weight.

Unsprung weight has a big impact on handling. Rotating mass (part of unsprung weight) has an impact on acceleration. The weight of brakes does not have as large of an impact on acceleration because it is not part of the rotating mass.

[csu87]

Originally Posted by tb30570

Did you replace the fuel pump with a higher flow rate model or install a bop? How much ethanol can the stock pump support...how much with a stock pump plus bop?

Upgraded lpfp

There's lots of info out there on running e85

[TrollToll]

Originally Posted by tb30570

Unsprung weight has a big impact on handling. Rotating mass (part of unsprung weight) has an impact on acceleration. The weight of brakes does not have as large of an impact on acceleration because it is not part of the rotating mass.

Wrong. He said brake rotors, and brake rotors are rotating mass.

[Nonecure]

Most people can run E30-E40 on a stock fuel pump. I have been running E40 for about 6 months now with no problem. E40 is nice because it is half E85 and half 93. It keeps me from having to do the high math at the pump.

You would only need to have 1 E40 tune and just dump a little more E85 in during the winter. If you go on a road trip, just switch to an off the shelf 93 tune and not worry about it.