Engine 89 Mustang Gt Engine Question

Welcome and congrats on the mustang. Take some advice from my 35 years of working on these cars, and don't take it as bashing,

What is the 70MM MAF off of? Is it Ford or aftermaket? The 70MM TB is a waste of money with your stock setup. You are probaby losing low end power. MSD distributors are junk and known to cause problems- best to put back a stock Ford distributor. Why are you running race plugs with a shorter electrode on stock iron heads? What heat range are they? Put a set of 3925's back in. You removed the catalytic converter- is the smog pump, thermactor tubes, and other emissions still on? What is your timing set at.

You are + or - 20 hp from stock of 225 flyweel hp

First thing to do is run the key on engine off and key on engine running codes.

ok so you have the following- not trying to get you to spend money, just letting you know whatto expect. In general, your motor is stock and the intake, heads and exhaust manifolds are all choke points. Adding a larger MAF and TB are not needed and probably arent doing anything at this point for you.

• C&L 76 MAF- garbage for the most part. If it's working leave it though
• 70MM TB- way too much for your stock motor and that you have the stock 58MM EGR plate is causing undo turbulence of air right before the injectors. The TB and EGR plate need to match.
  
• distributor- there is no need for you to have an aftermarket distributor. The stock Ford distributor and coil are good for at least 400hp and are better than most aftermarket. If the MSD is working now keep it but now that one day it will leave you stranded.
• If you removed the cats, there is no reason to still have the smog pump and hoses. Run a short belt and remove them. A smog deleted is a waste of money and not needed.
• Spark plugs- put a set of autolite 3925 copper plugs back in
• Timing- stock is 10 BTDC but most cars like 12-16.

Again, before you do anythin, run the codes. Sounds like the prior owner was either a kid or some nutswinger wannabe racer. Before you start throwing parts at it, know what it does, what the actual benefit is. Guys here have done whatever you can dream of already dozens of times and can help you avoing wasting time and money.

There are stickies on top of the forums and archives on how to set timing, check coded, set base idle and such.

Do yourself a favor and take his advice: it's the best you have gotten so far.


Far too many people put a dab of this and a dollop of that, and then wonder why the car doesn't run worth beans. Then they think off the shelf computer chips will fix their mismatched parts problem. It won't

You have to have a plan for what kind of performance you want: Hot street. Street/Strip, Pure strip, Autocross or Road course. Each one requires a different strategy and a different set of components.. Mismatch the components and you’ll have a car that falls flat on its face when you demand performance.

Everyone thinks HP! HP! HP! and thinks that peak HP is what they need. Peak HP is great for a drag strip car when it has the proper gears and tires to get the car up into the high RPM range where it develops that high peak HP near the finish line. On a street car, that strategy will have Honda Accords outrunning you, because you will never get the engine RPMs high enough without running over everything in your path.

Here’ the strategy: Always remember that there are some tradeoffs in any engine combination. Most of us don’t have enough money to “have it all” as if it was possible by some masterful combination of parts and tuning.

The following recommendations are for 5 Speed Manual transmission cars without NO2 or pressurized induction, stock short block.
1.) Hot street: Broad flat torque curve, high velocity airflow in the intake and heads for best throttle response. Gears suitable for reasonable gas mileage and long road trips without excessive engine RPMs. Stand on the gas pedal from a rolling start to squeeze into that gap in traffic in front of you, and it jumps quick and hard to get you there. Max RPM’s are 5200-5500 RPM for best power. Lopey cams may sound cool, but run poorly in a low RPM street environment.
Use stock cam, stock, GT40 or mildly ported stock heads, Cobra or Explorer/GT40 intake, advanced timing, stock 19 lb injectors, stock fuel pump. Use some good 1.6 or 1.7 ratio roller rockers for extra punch. Use a King Cobra clutch, with stock iron or steel billet flywheel. MAF cars can use a 65 MM TB from the Explorer intake manifold and a 70MM MAF from a 94-95 Mustang. Drive train: 3:55 gears with soft tread compound tires. Use some Ford Racing unequal length headers, stock 2 1/4” cat pipe and some mufflers that don’t drone or get too much attention from the law enforcement or neighbors. The stock computer will handle all this with no problems and doesn’t need any help in 90% of the cases. No skinny or grossly undersize tires for the front: remember you still have to stop quickly in traffic. Make sure all the rubber bushings in the front and rear suspensions are in first class shape. Leave the emissions equipment intact and working. Removing or disabling it won’t get you any more HP or performance. Do not convert to carb or remove A/C: either one will reduce the resale value. Carb conversions cannot be titled for street use or get tags in some places. They definitely won’t pass smog inspections.

Street/strip: A little more slope to the torque curve with a gently sloping peak. Use slightly larger port volumes on intake and heads for more peak HP. Uses 3.55 or 3.73 gears to get the RPM’s up into a higher range quicker. Be prepared to sacrifice some low RPM throttle response in exchange for high RPM power. This by necessity will be a Mass Air or Mass Air conversion on 86-88 5.0 Mustangs, since stock speed density will not run well with the changes in engine airflow. Don’t get too crazy on any one engine part since you still have to drive the car on the street, and a mismatch can make street driving miserable.
Use stock or mild aftermarket cam, Ported GT 40, or 165-180 CC port volume aftermarket aluminum heads. Use a Trick Flow, Edelbrock Performer or equal intake manifold. Take a 73 MM aftermarket MAF calibrated for 24 lb injectors, and 24 lb injectors, 155 LPH fuel pump, Kirban adjustable fuel pressure regulator. Be prepared to shell out some $$$ for a custom burned chip using data gathered from a dyno run. Mass market chips will not get the job done. Use some Ford Racing unequal length headers, aftermarket 2 1/2” cat pipe and some mufflers that don’t drone or get too much attention from the law enforcement or neighbors. Drivetrain: expect the stock T5 to fail, so save your money for a super duty 5 speed trans. Tremec 3550, TKO 500 & TKO 600 are the best choices. Different gears in a stock T5 case work for some, but there is only so much power you can pass through a T5 in race mode before it breaks, even with stronger gears. Next are the Chassis mods: full length subframe connectors, different springs, different shocks, aftermarket lower and upper control arms with rubber or urethane bushings. Buy all the parts from someplace like Maximum Motorsports, Griggs or Steeda as a kit so that you know that all the parts fit and don’t argue with each other. Carry spare tires and wheels for the drag strip: skinnys for the front and drag radials for the rear. No skinnys for street driving! Over 85% of the breaking power is generated by the front tires, so skinnys won’t do the job in a panic stop situation. Disconnect the front anti-roll bar at the strip; reconnect it before you drive home. Leave the emissions equipment intact and working. Removing or disabling it won’t get you any more HP or performance. Do not convert to carb or remove A/C: either one will reduce the resale value. Carb conversions cannot be titled for street use or get tags in some places. They definitely won’t pass smog inspections.

Strip only: High RPM, High flow heads (185-215 CC port volume), wild cam, high flow intake manifold, 70 MM or larger TB, 80 MM or lager MAF, strip everything out of the car that doesn’t make it go faster. Carbs are OK if that’s what you want, but remember that as the temp/humidity/ barometric pressure/altitude changes, you have to re-jet and readjust the carb. EFI eliminates most of that with its built in compensation or you can tune of the fly with a high end Motes or Tweecer system combined with a wide band air/fuel ratio meter. Use custom headers, dumps and minimal mufflers. How fast you can go on 5 liters is a function of the skill level of the driver/mechanic and the size of your wallet.

TRAILER the car to the race track since it won’t be legal to drive it on the street. Drag slicks in the rear, skinnys up front, use 3.73 or bigger gears (4.xx) in the rear axle. Since you won’t be driving on long trips, the big gears with work with the high RPM power curve to get the best results. Drivetrain: TKO 500 & TKO 600 are the best choices. Different gears in a stock T5 case work for some, but there is only so much power you can pass through a T5 in race mode before it breaks, even with stronger gears. Next are the Chassis mods: full length subframe connectors, different springs, different shocks, aftermarket lower and upper control arms with rubber or urethane bushings. Buy all the parts from someplace like Maximum Motorsports, Griggs or Steeda as a kit so that you know that all the parts fit and don’t argue with each other. Remove the front sway bar, put an airbag in the rear spring of the side that spins the tire the most. Plan on a roll cage if you are truly serious about going fast: most strips will require it once you get to a certain ET range.

Autocross is a combination of Hot street engine and street strip chassis prep. The engine must accelerate quickly from low RPM and needs a broad, flat torque curve. Next are the Chassis mods: full length subframe connectors, different springs, different shocks, aftermarket lower and upper control arms with rubber or urethane bushings. Buy all the parts from someplace like Maximum Motorsports, Griggs or Steeda as a kit so that you know that all the parts fit and don’t argue with each other. Most of the time you’ll never hit third gear, so some 3.73 or bigger gears (4.xx) may help a lot. You’ll have to spend some more money on brakes since it kills brakes quickly. Rear disks, larger rotors up front, stainless steel brake lines, different brake pads. A 87-88 T Bird Turbo Coupe or SN 95 rear axle will be your best bet. Autocross will severely strain 1st & 2nd gears, so your T5 may take a premature dump. Save your money for a super duty 5 speed trans. Tremec 3550, TKO 500 & TKO 600 are the best choices.

All out road race is the most difficult of all: an engine that will run at high rpm hour after hour and never fail, yet pull hard out of the hairpin turns that will require a lot of torque at lower RPMs. In my opinion, guys that can successfully build a winning road race engine are the cream of the crop. Top this off with a chassis built for strip only duty, but with changes to the settings of springs, tires, roll bars brakes and shocks. It’s a whole other world of racing.
You’ll have to spend lots more money on brakes since it kills brakes quickly. Rear disks, larger rotors up front, stainless steel brake lines, different brake pads. Air ducting to cool the brake rotors will be a must. The brake rotors of cars on a high speed road course glow red after several hard laps of racing. Drivetrain: TKO 500 & TKO 600, and T56 close ratio are the best transmission choices.

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leehart said:

I have an 89 LX Convertible, 5spd, factory deleted AC...do the same rules apply to the 5.0l in my car since it's NOT a GT or a Cobra? looking for Hot Street style performance as this car will not be raced (it's my baby with only 87000 kms). I am planning on changing out the stock 2.73 rear end to a 3.55 as the starting point, followed by clutch when needed. Does a guy need to do subframe connectors?

sent from an archery range somewhere near you.

Click to expand...

@leehart - engines are identical, its the body panels that differ, your rear gear is a 3.08 w/ the T5, 2.73 didnt come on that combo. It would be much better to start your own thread as to not confuse and clutter the OP's thread

My apologies.

sent from an archery range somewhere near you.