Finally read the whole thing. Great tips, very nice of you to write all of this up. Thanks!
-Chris
great tips
To help people understand what fuels are what for a turbo BMW here are some facts. Note that it's not as simple as "the higher the octane the better". Many other factors come into it.
Please take a look at the VP Racing Fuels site
Unleaded Fuels
MOTORSPORT 109
Produces more power than any other unleaded fuel. Recommended for higher boost applications with CRs up to 11:1 or naturally aspirated engines up to 13:1.
• Color: Clear
• Motor Octane: 101
• R+M/2: 105
• Research Octane: 109
• Oxygenated: Yes
• Specific Gravity: .722 at 60° F
Streetblaze 100
Oxygenated with ethanol, this CARB-legal fuel is specifically engineered for high-performance street cars including sport compacts, muscle cars, street rods and more. It's environmentally friendly and street legal throughout the U.S. In applications with anything from 4- to 12-cyclinders or engines equipped with a turbocharger, supercharger or nitrous oxide system (NOS), StreetBlaze 100 will generate optimum power and performance. In turbocharged or supercharged applications, it allows an increase in boost without fear of detonation. NOS users can also leverage their higher octane ratings to step up to a more powerful nitrous oxide system. Dyno tests with a turbocharged application proved StreetBlaze100 generates up to 14% more horsepower compared to premium grade 91 octane unleaded gasoline. Designed for use in cast-iron head engines with CRs up to 13:1 and aluminum head engines up to 14:1. Works well on the latest generation of electronically-controlled turbo engines. Contains no metal compounds and won't harm catalytic converters or oxygen sensors.
• Color: Orange
• Oxygenated: Yes
• Motor Octane: 96
• R+M/2: 100
• Specific Gravity: .746 at 60° F
MOTORSPORT 101
This 101 octane (R+M/2) fuel allows an increase in timing and more powerful nitrous oxide systems, with substantial power increases compared to premium pump gas. Designed for CRs up to 13:1 in cast-iron head engines and up to 14:1 with aluminum heads, MS101 is particularly effective in turbo- and supercharged applications. It contains no metal compounds and won't harm catalytic converters or oxygen sensors.
• Color: Yellow
• Motor Octane: 99
• R+M/2: 101
• Oxygenated: Yes
• Specific Gravity: .800 at 60° F
MOTORSPORT 103
MS103 provides power and protection equal to some leaded racing fuels. Compared to Motorsport 101, it allows even more aggressive timing and higher compression-up to 14:1 in cast iron head engines and up to 15:1 with aluminum heads. Can allow doubling of stock boost - consult your engine builder. Also contains no metal compounds and won't harm catalytic converters or oxygen sensors. AMA legal for Supercross & Outdoor Nationals.
• Color: Red
• Motor Octane: 99
• R+M/2: 103
• Oxygenated: Yes
• Specific Gravity: .743 at 60° F
Leaded Fuels
C16
Used in turbocharged engines, blown engines and nitrous applications with CRs up to 17:1. Recommended by the top nitrous oxide companies. Spec Fuel for NHRA Comp Eliminator.
• Color: Blue
• Motor Octane: 117
• Specific gravity: .735 at 60° F
VP Import
Maximum power and torque in small displacement, high RPM, all motor, turbocharged or nitrous sport compact applications. Makes 5% more power than C16 and similar nonoxygenated fuels. Works well under high temperatures due to mechanical heat.
• Color: Clear
• Motor Octane: 120+
• Specific Gravity: .744 at 60° F
.-=[ Kenny ]=-. See the BFc Drag Racing Standings List for BMW street cars. Watch my drag racing movies on YouTube. Some info on
BMW turbo street car Drag Racing 101
way to go on the write up man.
Gearing Basics
To determine your optimum gearing you need to know the following:
+ The rubber under your rear guards
+ Your engine's redline
+ Your gearbox ratios
+ Your diff ratio
+ Your car's trap speed on it's best ever pass
Given that the optimum rubber you can fit under your BMW street car for drag racing purposes is the tallest and widest rubber that will fit, click on the link in my sig to find the optimum rubber for your car (or look for the post near the top of this thread).
You must work out what gearbox you are running and what the gearing is for each gear. It's also important to note whoch gear is your 1:1 gear. Optimally you want to be one car length past the finish line when you hit redline in your 1:1 gear.
Once you know your engne redline, optimum rubber and your gearbox ratios, you can then calculate the best diff ratio, given that you know the best trap speed you've ever hit. If you expect to make mods to improve your trap speed, then go test it before changing your diff rato.
Your objective is to calculate what diff ratio will give you 1-2 MPH higher than your best ever trap speed at redline in your 1:1 gear. There are a limited choice of diff ratios available depending on what BMW model you have. You may end up finding a great match in the gear lower than your 1:1 gear (for example 4th rather than 5th). Or you may end up more than 1-2 MPH under your best trap speed. That's OK, you are working towatrds your optimum setup and doing the best you can.
For specific examples or calculations just post a request thread and I will help.
.-=[ Kenny ]=-. See the BFc Drag Racing Standings List for BMW street cars. Watch my drag racing movies on YouTube. Some info on
BMW turbo street car Drag Racing 101
Guys, last night I fit a set of Hoosier slicks on my car(Kenny, I'll post pictures and sizes for your thread) but, the car got crazy.
It felt unstable even at 80mph.
I was running 20psi in the slicks and street radials up front.
Do I have to run skinnies? If not, what are other people using?
-Dave
TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.
The slicks were cold. I was crusing to check for rubbing.
I stood on them a few times and lost grip. I tried to hold the throttle down to see what they would be like at 120+, but, I didn't make it past 80 mph.
I used DR's once and they seemed "fine" not squirrley at all.
Should I try to let air out of the fronts?
-Dave
TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.
Don't mix slicks with radials. Your front runners should be at a high pressure, and your slicks should start out at a fairly high pressure and gradually reduced.
On our cars we have relatively very small slicks with relatively very heavy cars. Racing slicks were designed for much lighter race cars that can fit much larger slicks.
So start with 24 or 26 psi in your slicks and reduce by 1 psi until your short time gets worse. Do not listen to those who tell you they run 6 psi in their car ... their car probably weighs 2100 lbs.
.-=[ Kenny ]=-. See the BFc Drag Racing Standings List for BMW street cars. Watch my drag racing movies on YouTube. Some info on
BMW turbo street car Drag Racing 101
Kenny, here are some pics of the 26x8x15 Hoosier slick fitted under stock M3 bodywork. My fenders are not rolled, but, could use it.
-Dave
TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.
OK, so what rims are you running and did they fit over the stock calipers or did you have to do some sort of surgery to them?
2015 E84 X1 35i ///M +JB4
__________________________________________________ __________________________________________________ _____________________________
RIP --- 98 ///M3 Mods:- Eurosport TS - (EVO)Euro 6-speed
.-=[ Kenny ]=-. See the BFc Drag Racing Standings List for BMW street cars. Watch my drag racing movies on YouTube. Some info on
BMW turbo street car Drag Racing 101
Unfortunately I've lost the permissions to edit my previous posts .. not sure if this is temporary or not. I cannot update the rubber fitment post with this new information Dave.
.-=[ Kenny ]=-. See the BFc Drag Racing Standings List for BMW street cars. Watch my drag racing movies on YouTube. Some info on
BMW turbo street car Drag Racing 101
.-=[ Kenny ]=-. See the BFc Drag Racing Standings List for BMW street cars. Watch my drag racing movies on YouTube. Some info on
BMW turbo street car Drag Racing 101
great writeup
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