My sister bought a new mustang cobra last year, its totally stock. I bought a 91 305TPI Z28 a while back and brother in law was always talking about how my sister could smoke my car, which I am sure was true. Now I just bought a 91 Formula with a 5.7L and WS6 package. It is stock also. What do you think I would need to do to it to beat my sister and shut up my brother in law? By the way she has a stick and mines an automatic and neither of us have any experieince at real racing.

 

Get it tuned up and running 100% with new cap and rotor, new plugs and plugwires, etc first before worrying about any mods.

Then I would do several mods, starting with the exhaust. I think you'll want a set of SLP headers, and a decent cat-back setup. Then I'd port the plenum (if you have a dremel you can do this, pull off the throttle body and you'll see the EGR walls blocking half the opening at the plenum inlets, grind them down flush with the floor of the plenum). Then I'd get an Adjustable Fuel Pressure Regulator and bump the fuel psi a bit, and get a K&N filter setup and try to pipe some cold air to whatever setup you do with the filter.

With all that I think you could take her if you launch right. May take another small bolt on two depending on just how strong her car is and how well she can drive the stick. I think you would take the win...

 

I agree with Ray87Z on what to do to your car. The next thing would be some good tires for traction off the line. The Nitto 555R drag radials work well and have good milage.

 

if those things are anything like my car to launch and she doesn't have any real racing experience you will prolly win

problem with cars and IRS is they work great for road racing
but suck when trying to drag race
you are not able to keep the wheels on the ground at all and they just want to bounce around

 

OKay, At the risk of appearing really stupid, Ive been seeing IRS around a bit and after some serious pondering I've come up with Independent Rear Suspension! Apparently Mustangs have that and that's why you are saying that they are not good for drag racing, but are good for roadx racing. Im still a bit of a novice at this.

Another question, if I port my plenum (sounds obscene) like was suggested on here, will it affect emissions, will I still be able to pass an emissions test? They just tightened up restrictions here in Houston because of air pollution. It sounds easy, and yes a already have a dremel tool (making Pinewood derby cars, haha).

 

there will be no effect on your emmisions if you port he plenum. you will be allowing more air to enter the intake, thats it. I would also install a 160 or 180 degree thermostat so your engine stays at a colder temp while driving. TPI engines love cold temp, and you could see a couple tenths reduction in your quarter mile times because of the engine temp being in between 160 and 180. I have a 160 stat in my Vette, an the temp gauge stays at 155-160 while cruising. It never gets past 180, even while idling at a stoplight. Then, if someone pulls up next to me, im always at race-ready temp.

 

I always thought that the higher the temp on the motor the better it would run
but the colder the air the better also

the problem comes with you get a warm motor then you will make the air going into the intake warmer and will make it lose density. jalso if you run the motor too warm you will have detonation and stuff like that

but I do not really see any problem with porting the plenum and emissions as long as you do not go and port the crap on the thing.
also can't you port the intake runners so the car will make power in the higher rpms range?

as for the TB get a airfoil or if you want you can smooth it out yourself as I have done on some TB

exhaust should be the first mod you do though. everything after that will have a lot bigger of an effect then just by itself.

and if you could I would bolt a straight pipe in and then swap it around when smog comes up so you cna still pass.

 

I beat a new saleen in my 89 formula three times one night. Once from a stop and twice from rolls of 10-20mph up to 80 or so. I suspect he may have gained ground from 80-110 or so, maybe not catch me though. The saleen is basically the GT, not a cobra however. My car is in good tune and has basic bolt ons (slp headers/catback, slp CAI, afpr, pulley and other minor things). I now have new tranny w/ transgo and vigilante so would probably fare even better from a stop if I could get traction.

 

You want a motor to run cooler than ours did stock. But you don't want it to cold. A 160* stat would be good to allow the engine to run cooler and have cooler under hood temps entering the intake. But with a TPI would a 160* affect the computer?

 

Go with 180*

 

I would race her bone stock, if she is not use to driving that modular motor and and stick shift aggressively. You might just take her. They make all their power up top, so they are hard to launch corrrectly. If you can take her off the line, she will probably get nerves and miss a gear. She will pull hard on you up top, but if she is not powershifting and you get a real good jump on her off the line, you might just suprise her.
And if you do lose atleast you will have some idea of how much faster you need to make your car.

Nick

 

160 in most cases for an cc motor is too cool . the computer doesnt know what the hell to do . but makes my non cc lg4 run like a champ

 

I just installed a 160 stat in my L98 89' Vette about 2 weeks ago, and no problems yet. My temp stays at 160 all the time while crusing. Then wen i meet someone at a red light, the temp is race ready. TPI motors love cooler temperatures. The computer in GM cars is designed to provide the correct amount of fuel and spark advance for whatever the temp is at. Dont worry.