a FEW questions

ace2600 · 06-15-2001, 07:11 PM

Hey I am new to the mustang world. Ive been reading everyones post for about a month now and their are several things im confused about. Please help explain what some of these mean.

W.O.T
injectors 24 lb, 47psi
FPR
gearing 3:73 4:10(what does it mean?)
ET
SO and HO
31, 33, etc splines
Blower vs Supercharger (the difference?)
timing @ 18degrees etc.
this is all the ?'s im going to ask for now. Any help will be greatly appreciated!
-Ace

Oldschoolpony · 06-15-2001, 07:34 PM

I'll take a crack at some of them.
Injectors,-fuel injectors, the lb means what size( output) I use carbs so thats about as far as I can go there.
PSI. Fuel pressure
3:73, 4:10 is the gear ratio in the rear end.( differential)
SO=?
HO short for High output
31 & 33 splines is the amount of teeth on the inner end of the axle shaft.
timing @ 18 deg. ect. the point where the spark plugs fire.
Its more complicated than that, but typing isnt my thing so I tried and keep it simple.

93CobraR · 06-15-2001, 07:36 PM

1. Wide Open Throttle (Gas to the floor)
2. 24 is the size of the fuel injectors and 47 psi. is what the fuel pressure is set at.
3. Fuel Pressure Regular, adjust fuel pressure(refer to #2.
4. The ratio a the driveshaft spins 3.73 time for each time the tire goes around 1 time.
5. SO??? HO is High Output
6. the number of splines on a axle, there like grooves.
7. Blower mounts in place of the intake, and a supercharger is mounted on the front.
8. 18 degrees is what the timing on the car is set at.
These are my deffenitions....
Also welcome to Mustang Works!

------------------
87 GT, 4 inch cowl hood,17x9 Cobra R's/255/45's,GT-40 heads,Crane 2031, Edelbrock intake, long tubes headers,h-pipe,Flows,BBK cold air, Mass air,70mm MAF, 1.7's, 1" spacer,underdrive pulleys,Pro 5.0, King Cobra, Adj. fuel Reg., Lakewood Lift Bars,50/50's,subframes, 4.10's.
Best time 12.759
Best MPH 106.79
Best 60' 1.695

Visit my site at:
http://www.geocities.com/cobrar93_2000/MyPage.html

jimberg · 06-15-2001, 09:56 PM

WOT's been covered.

Fuel Injectors
When we say 24 lb injector, it means that if it were just a nozzle, you'd be able to inject 24 lbs of fuel through it in an hour if the pressure of the fuel is at 39 psi. By raising the fuel pressure to something like 47 psi, you can increase the output of the fuel injector. The formula is Sqrt( Target fuel pressure / 39psi ) * Injector Rating. e.g. Sqrt( 47 / 39 ) * 24 = 26.35 lbs/hour.

This is important since an engine uses a certain amount of fuel per horsepower per hour. This is called the BSFC (Brake Specific Fuel Consumption). We generally use .5 (.55 is probably more accurate for a naturally aspirated engine) for a rough estimate since it makes calculating easy. The formula is basically ( injector rating * BSFC * No. of Injectors * 0.85 ) Injectors aren't just nozzles that can operate at 100% duty cycle. They open and close which takes time. 85% duty cycle is about all they should be expected to produce. That's why the 0.85 is in the formula. So, for example, 24lb injectors should be able to support 24 * .5 * 8 * 0.85 = 326 HP safely.

Don't confuse this to mean that if you slap 24 lb injectors on your car that you will have 326 hp. You need air to go with that. About 13 lbs of air for every lb of fuel for optimal power.

Blower vs. Supercharger
Blower and supercharger are synonymous. A supercharger is a device that is driven by the engine to force air into the intake. It's usually belt driven.

ET
Simply the elapsed time it takes to cover the length of a drag strip whether 1/8 or 1/4 mile.

Timing @18 degrees
Read the My head choice dilema.. thread for more info. For here, I'll just say it's the number of degrees left for the crank to rotate before the piston hits top dead center. This is the base point at which the computer will send a spark to ignite the air/fuel mixture. I say base point because timing gets advanced as RPMs increase. The 18 degrees is the point at which the computer will start advancing the timing. Total timing is the total number of degrees of advance + the base timing. The computer usually advances about 20 degrees at max rpm under max load so total timing would be 38 in the example you used.

I guess that should about cover it.

------------------
351W 89 Mustang GT Convertible

ace2600 · 06-16-2001, 12:02 AM

Wow, that was a huge help. Here are a few more questions. Thanx for all the help!
What are:
differnet types of superchargers (roots, etc)
a-trim, s-trim
CFM
MAF
do the same mods on a 90-93 5.0 work on the 94-95 5.0 (just for the engine, not the car)OEM and OE
Thanx again!
-ace

QuantumMotorsports · 06-16-2001, 12:32 AM

SO is standard output,
MAF is Mass Air Flow (refering to the meter on the intake)
CFM is cubic feet per minute (flow rate)
OEM is original equipment manufacturer and OE is original equipment

the mods for the 5.0 motor are pretty much the same for the 87-95 except for the difference between mass air and speed density motors. The intakes on the 94-95 engines are different because of the hood (clearance) Hope that helps.

------------------
Michael Black
Quantum Motorsports
Norman, Oklahoma

1988 Merc Cougar 5.0 HO, Ported and Polished E7TEs, 2.25" offroad H pipe w/ 2 chamber flowmasters, T5 tranny
New E/T!!!
14.626 @ 94.94mph, 2.194 60' time, a little better than last time. Keep in mind this thang is heavy (3590lbs) Finally 14s!!!!

Unit 5302 · 06-16-2001, 12:35 AM

Q. Differnet types of superchargers (roots, etc)

A. There are 3 main styles of superchargers. Centrifugal, Roots, and Twin Screw. The basic info on the three goes about like this. Centrifugal is the most popular and common form of supercharger on the market. It takes less power to operate than either the Roots style or Twin screw style blowers. Roots blowers are called postive displacement since they literally scoop and force air into the induction system. Roots blowers take a lot of power to run, and they are generally inefficient at producing power. That being said, they can make phenominal amounts of power, and they are much better at producing boost levels at lower rpms than centrifugal types. The third, and least common is the Twin Screw (also positive displacement). The twin screw systems actually replace the upper intake on the 5.0, they are the best of the three at producing low rpm boost. They have no lag time (or time between you pressing down the pedal to the time boost is made), unlike the roots, and much unlike the centrifugal. The twin screw superchargers are not found in ample supply at the drag strips.

Q. A-Trim, S-Trim?

A.These are two different models of the Vortech supercharger family. The S-Trim is superior in output to the A-Trim, it's built better and it is capable of holding up under higher boost levels. There are more versions availible as well, you may see T-Trim, R-Trim or a few others.

Q. CFM?

A.Abbreviation for "Cubic Feet per Minute." It's generally used to compare flow rates between products. More air = more power, as long as the setup is matched right.

Q. MAF?

A.Abbreviation for "Mass Airflow" or "Mass Airflow Sensor." It's a sensor on 1988 (California), or 1989 and later Mustang V-8's. It allows for real measurement of air coming into the engine, whereas the older SD "Speed Density" system uses stored baseline information.

Q. Do the same mods on a 90-93 5.0 work on the 94-95 5.0 (just for the engine, not the car)OEM and OE.

A. For all intensive purposes, the 1987-1995 Mustang 5.0's all have the same engine, except for the Cobra models. Athough a few modifications for the are Fox 1987-1993, or SN95 1994-1995 specific (such as intakes), the same basic modifications will net you about the same performance improvements. The heads are the same E7TE truck castings 1.78" intake valves, 1.46" exhaust from 1987-1995, the camshaft was slightly revised in 1989, but it's nearly the same as the SD cars. The intake changed in 1994, but it kept about the same performance rate. The MAF sensor is the same from 1988 (California) thru 1995 as well. The block is the same for sure from 1985-1995.

06-15-2001, 07:11 PM	#1
ace2600 Registered Member Join Date: May 2001 Location: Houston, Texas Posts: 33	a FEW questions Hey I am new to the mustang world. Ive been reading everyones post for about a month now and their are several things im confused about. Please help explain what some of these mean. W.O.T injectors 24 lb, 47psi FPR gearing 3:73 4:10(what does it mean?) ET SO and HO 31, 33, etc splines Blower vs Supercharger (the difference?) timing @ 18degrees etc. this is all the ?'s im going to ask for now. Any help will be greatly appreciated! -Ace

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06-15-2001, 07:34 PM	#2
Oldschoolpony Registered Member Join Date: Mar 2001 Location: Gainsville,Fl Posts: 229	I'll take a crack at some of them. Injectors,-fuel injectors, the lb means what size( output) I use carbs so thats about as far as I can go there. PSI. Fuel pressure 3:73, 4:10 is the gear ratio in the rear end.( differential) SO=? HO short for High output 31 & 33 splines is the amount of teeth on the inner end of the axle shaft. timing @ 18 deg. ect. the point where the spark plugs fire. Its more complicated than that, but typing isnt my thing so I tried and keep it simple.

06-15-2001, 07:36 PM	#3
93CobraR Registered Member Join Date: Oct 1999 Location: Cincinnati, Ohio Posts: 1,575	1. Wide Open Throttle (Gas to the floor) 2. 24 is the size of the fuel injectors and 47 psi. is what the fuel pressure is set at. 3. Fuel Pressure Regular, adjust fuel pressure(refer to #2. 4. The ratio a the driveshaft spins 3.73 time for each time the tire goes around 1 time. 5. SO??? HO is High Output 6. the number of splines on a axle, there like grooves. 7. Blower mounts in place of the intake, and a supercharger is mounted on the front. 8. 18 degrees is what the timing on the car is set at. These are my deffenitions.... Also welcome to Mustang Works! ------------------ 87 GT, 4 inch cowl hood,17x9 Cobra R's/255/45's,GT-40 heads,Crane 2031, Edelbrock intake, long tubes headers,h-pipe,Flows,BBK cold air, Mass air,70mm MAF, 1.7's, 1" spacer,underdrive pulleys,Pro 5.0, King Cobra, Adj. fuel Reg., Lakewood Lift Bars,50/50's,subframes, 4.10's. Best time 12.759 Best MPH 106.79 Best 60' 1.695 Visit my site at: http://www.geocities.com/cobrar93_2000/MyPage.html

06-15-2001, 09:56 PM	#4
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	WOT's been covered. Fuel Injectors When we say 24 lb injector, it means that if it were just a nozzle, you'd be able to inject 24 lbs of fuel through it in an hour if the pressure of the fuel is at 39 psi. By raising the fuel pressure to something like 47 psi, you can increase the output of the fuel injector. The formula is Sqrt( Target fuel pressure / 39psi ) * Injector Rating. e.g. Sqrt( 47 / 39 ) * 24 = 26.35 lbs/hour. This is important since an engine uses a certain amount of fuel per horsepower per hour. This is called the BSFC (Brake Specific Fuel Consumption). We generally use .5 (.55 is probably more accurate for a naturally aspirated engine) for a rough estimate since it makes calculating easy. The formula is basically ( injector rating * BSFC * No. of Injectors * 0.85 ) Injectors aren't just nozzles that can operate at 100% duty cycle. They open and close which takes time. 85% duty cycle is about all they should be expected to produce. That's why the 0.85 is in the formula. So, for example, 24lb injectors should be able to support 24 * .5 * 8 * 0.85 = 326 HP safely. Don't confuse this to mean that if you slap 24 lb injectors on your car that you will have 326 hp. You need air to go with that. About 13 lbs of air for every lb of fuel for optimal power. Blower vs. Supercharger Blower and supercharger are synonymous. A supercharger is a device that is driven by the engine to force air into the intake. It's usually belt driven. ET Simply the elapsed time it takes to cover the length of a drag strip whether 1/8 or 1/4 mile. Timing @18 degrees Read the My head choice dilema.. thread for more info. For here, I'll just say it's the number of degrees left for the crank to rotate before the piston hits top dead center. This is the base point at which the computer will send a spark to ignite the air/fuel mixture. I say base point because timing gets advanced as RPMs increase. The 18 degrees is the point at which the computer will start advancing the timing. Total timing is the total number of degrees of advance + the base timing. The computer usually advances about 20 degrees at max rpm under max load so total timing would be 38 in the example you used. I guess that should about cover it. ------------------ 351W 89 Mustang GT Convertible

06-16-2001, 12:02 AM	#5
ace2600 Registered Member Join Date: May 2001 Location: Houston, Texas Posts: 33	Wow, that was a huge help. Here are a few more questions. Thanx for all the help! What are: differnet types of superchargers (roots, etc) a-trim, s-trim CFM MAF do the same mods on a 90-93 5.0 work on the 94-95 5.0 (just for the engine, not the car)OEM and OE Thanx again! -ace

06-16-2001, 12:32 AM	#6
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	SO is standard output, MAF is Mass Air Flow (refering to the meter on the intake) CFM is cubic feet per minute (flow rate) OEM is original equipment manufacturer and OE is original equipment the mods for the 5.0 motor are pretty much the same for the 87-95 except for the difference between mass air and speed density motors. The intakes on the 94-95 engines are different because of the hood (clearance) Hope that helps. ------------------ Michael Black Quantum Motorsports Norman, Oklahoma 1988 Merc Cougar 5.0 HO, Ported and Polished E7TEs, 2.25" offroad H pipe w/ 2 chamber flowmasters, T5 tranny New E/T!!! 14.626 @ 94.94mph, 2.194 60' time, a little better than last time. Keep in mind this thang is heavy (3590lbs) Finally 14s!!!!

06-16-2001, 12:35 AM	#7
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Q. Differnet types of superchargers (roots, etc) A. There are 3 main styles of superchargers. Centrifugal, Roots, and Twin Screw. The basic info on the three goes about like this. Centrifugal is the most popular and common form of supercharger on the market. It takes less power to operate than either the Roots style or Twin screw style blowers. Roots blowers are called postive displacement since they literally scoop and force air into the induction system. Roots blowers take a lot of power to run, and they are generally inefficient at producing power. That being said, they can make phenominal amounts of power, and they are much better at producing boost levels at lower rpms than centrifugal types. The third, and least common is the Twin Screw (also positive displacement). The twin screw systems actually replace the upper intake on the 5.0, they are the best of the three at producing low rpm boost. They have no lag time (or time between you pressing down the pedal to the time boost is made), unlike the roots, and much unlike the centrifugal. The twin screw superchargers are not found in ample supply at the drag strips. Q. A-Trim, S-Trim? A.These are two different models of the Vortech supercharger family. The S-Trim is superior in output to the A-Trim, it's built better and it is capable of holding up under higher boost levels. There are more versions availible as well, you may see T-Trim, R-Trim or a few others. Q. CFM? A.Abbreviation for "Cubic Feet per Minute." It's generally used to compare flow rates between products. More air = more power, as long as the setup is matched right. Q. MAF? A.Abbreviation for "Mass Airflow" or "Mass Airflow Sensor." It's a sensor on 1988 (California), or 1989 and later Mustang V-8's. It allows for real measurement of air coming into the engine, whereas the older SD "Speed Density" system uses stored baseline information. Q. Do the same mods on a 90-93 5.0 work on the 94-95 5.0 (just for the engine, not the car)OEM and OE. A. For all intensive purposes, the 1987-1995 Mustang 5.0's all have the same engine, except for the Cobra models. Athough a few modifications for the are Fox 1987-1993, or SN95 1994-1995 specific (such as intakes), the same basic modifications will net you about the same performance improvements. The heads are the same E7TE truck castings 1.78" intake valves, 1.46" exhaust from 1987-1995, the camshaft was slightly revised in 1989, but it's nearly the same as the SD cars. The intake changed in 1994, but it kept about the same performance rate. The MAF sensor is the same from 1988 (California) thru 1995 as well. The block is the same for sure from 1985-1995.