NHRA E.T. Quick Reference Guide | Performance Calculators | Turbo Glossary

2006 NHRA E.T. Quick Reference Chart
(Posted as a convenience for our viewers.  Top End Fabrication is not responsible for any typographical errors. Content gathered from NHRA's 2006 ET Reference Chart)
Quarter-Mile e.t.s 6.00 to 7.49 7.50 to 9.99 10.00 to 10.99 11.00 to 11.49 11.50 to 13.99 14.00 & Slower
Aftermarket Rear Axles Y Y Y 2:11 2:11 2:11
Arm Restraints
(Open Cars)
Y Y Y Y 10:3
Auto Trans Flexplate
(SFI 29.1)
Y Y 2:14 2:14 2:14 2:14
Auto Trans Reverse Lockout Y Y Y Y Y Y
(SFI 6.1/6.2)
Y Y Y Y 2:10 2:10
Driver Restraint System
(SFI 16.1)
Driveshaft Loop Y Y Y Y 2:4 2:4
Electric 16.00 & Quicker Y Y Y Y Y 2:4
Flexplate Shield
(SFI 30.1)
Y Y 2:14 2:14 2:14 2:14
(SFI 1.1/1.2)
Y Y Y Y 2:5 2:5
Harmonic Balancer
(SFI 18.1)
Y Y Y Permitted Permitted Permitted
Helmet (Snell 95 or SFI 41.1A min.) Y Y Y Y Y 10:7
Liquid Overflow Y Y Y Y Y Y
Master Electrical Cutoff Y Y 8:4
135 mph
8:4 8:4 8:4
Neck Collar Y Y 10:8 10:8 10:8 10:8
NHRA Competition License Y Y 10:4 10:4 10:4 10:4
NHRA Chassis Sticker Y Y 4:4 4:4 4:4 4:4
Padding Roll Bar/Cage Y
Y Y Y 10:6
135 mph
135 mph
Parachute Y Y 4:8
150 mph
4:8 4:8 4:8
Pressurized Bottles
DOT (1800)
Protective Clothing Y Y Y Y 10:10 10:10
Roll Bar     Y Y C/13:49 4:10
Roll Cage Y Y
135 mph
4:11 4:11 4:11 4:11
SFI Chassis Specification Y 4:4
180 mph
4:4 4:4 4:4 4:4
Supercharger Restraints Y 1:15 1:15 1:15 1:15 1:15
Taillight Y Y Y Y Y Y
Transmission Shield
(SFI 4.1)
Y Y Y 2:14 2:14 2:14
Window Net
(Full-Bodied Cars)
Y Y 6:3
Y = Required C= Convertibles
Number Refers to General Regulations
In no way is this Quick Reference Chart intended to supersede or replace the current NHRA Rulebook

Performance Calculators
These calculators are to be used as an estimating tool only. 
There are many variables involved that would alter the outcome of any of these formulas.

From Hardcore50
Calculate HP from known Performance and Weight
Calculate Performance from known HP and Weight
Calculate ET and MPH
Calculate HP from ET and Weight
Calculate HP -vs- Altitude
Calculate HP required to run a given MPH
Calculate HP necessary to sustain a given MPH
Calculate Engine Displacement
Calculate Header Dimensions
Calculate Optimum Carburetor Size
Calculate Fuel Injector Size -vs- Horsepower Level
Calculate RPM for Speed in Gear
Calculate Speed for RPM in Gear
Calculate HP, Weight, Shift Points, Gears, and Tires
Automotive Math Formulas

From Stan Weiss Worldwide Enterprises

Calculate Rear Gear Ratio Needed
Estimate the Horsepower gain from adding Blower Pressure

Turbocharger Glossary
(All the turbo-related definitions you need)

Blow-Off Valve
Compressor Surge

A/R: A formula used to determine the size of the compressor and turbine housing configuration. The letters stand for Area divided by Radius, where Area is the cross-sectional area of the scroll (the finned wheel), and Radius is the shortest distance from the centerline of A to the centerline of the turbine shaft. The basic rule of thumb about A/R: A turbo with a smaller A/R value will spool up quicker and be more responsive, though it won't produce as much peak power as one with a larger A/R value. The turbo with the larger A/R value has the greater capacity to produce power, but will spool up slower and exhibit turbo lag.

Bar: A means of expressing air pressure, like psi. A measurement of 1.0 bar translates to 14.7 psi, which is equivalent to normal atmospheric pressure at sea level.

Bearings: The shaft between the turbine and compressor wheel rides on bearings inside the turbo's center housing. In a standard turbo those bearings are made of metal, and a thin film of oil separates the shaft from the bearings. These bearings do wear, but they can be rebuilt if damaged. Some turbos use ball bearings in the center housing instead of metal bearings, which reduces friction and speeds up the turbo's response time. Ball-bearing turbos are pricey to rebuild, though. If you damage a ball-bearing turbo, you may have to sell your sister to rebuild it.

Blow-Off Valve: A device used to release excess pressure in the intake system between the compressor wheel and the throttle plates, to prevent compressor surge. Also known as a Pop-Off Valve.

Boost: A measure of the air charge sent from the compressor to the combustion chamber, typically indicated in either pounds per square inch (psi) or bar.

Compressor: The finned wheel on the intake side of the turbocharger that is driven by the exhaust-side turbine. It sucks fresh air through the center inlet, compresses it, and sends it to the combustion chambers. (Sometimes by way of an intercooler.)

Compressor Surge: A condition caused by compressed intake air caught between the compressor wheel and closed throttle plates. When you get off the throttle after a burst of acceleration, the plates close but the compressor wheel may still be sending compressed air into the system. If the compressed intake charge cannot flow through the throttle plates, it will flow back to the compressor, which could result in bearing damage.

Downpipe: The pipe that carries exhaust gas away from the turbine side of the turbocharger and into the exhaust system. A large-diameter, free-flowing downpipe eases backpressure that could impede the exhaust flow at the turbine and slow it down.

Housings: The snail-shaped enclosures inside of which the turbine and compressor wheels spin. Like A/R, housing shape and size have a tremendous effect on the turbocharger's output, as well as its ability to dissipate heat. A turbo with a larger housing can produce higher boost, and therefore higher horsepower, but is generally slower to spool. A turbo with a smaller housing spools quicker but cannot make high levels of boost.
Top End Fabrication Home Page Services Top End Fabrication Provides Top End Fabrications Photo Galleries NHRA Quick ET Reference, Performance Calculators, Turbo GlossaryUser Forums & Classifieds COMING SOON! Click Here to E-Mail Top End Fabrication AeromotiveAnthony Jones EngineeringBig Stuff 3Dynamic Racing TransmissionsF.A.S.T.Garret TurbochargersHogans Racing ManifoldsNitrous Oxide SystemsPrecision TurboProchargerProline Race EnginesS&W Race CarsTiAL SportTurboneticsUPR ProductsWolfe Racecraft