Ok, looking into purchasing a 1991 Camaro. 5.7L, 5 speed...can anyone tell me what these cars came equipped with as far as a system to measure air? It is a TPI car, just need to know if 91 was speed density...speed density is the better of the two, correct? Also, any other option info would be good, don't know it it's a Z28 yet, haven't checked out the car so far....disc brakes, posi, info on those subjects would be nice... Thanks in advance!

 

yes, it is a speed density system.
Which one is better is debatable(sp?).
Oh, if it is a 5.7 5 speed, it probably is not stock, or it's really a 5.0liter 5 speed.


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WS6 Trans Am.

View My Ride @ thirdgen.org

[This message has been edited by Zepher (edited October 20, 2001).]

 

probably not stock, or decidely not stock? Guy i talked to over the phone was probably around late 50's to early 60's, might be a one owner car...did they not put the 5.7 with a stick behind the 91? Or is it just rather rare?

 

3rd gens never came with 350's and a stick.check the 8thh digit on the vin if it is an f it's a 305 car an 8 designates a 350.

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87 trans am,gm crate 350(4 bolt mains 10to1),L98 aluminum heads,LT4 hot cam,slp runners,slp 1 5/8 headers,3in.y-pipe,edelbrock base,hi flo cat,air foil,afpr,as&m ported plenum,gutted airbox,t-5 tranny w/centerforce clutch and a 3.27 9bolt(11.9in. brakes),ed wright's fastchip,relocated iat sensor,160 fan switch&t-stat,tb bypass,accel supercoil,cap& rotor,slp 3in. catbcak,a/c delete.

SHE IS GONE BUT I KNOW THE GUY WILL GIVE HER A GOOD HOME.

best e/t:
3653lbs./full tank+ driver.
14.10@96.53mph 2.01 60'

 

MAF vs. speed density part of your question.

GM started out by putting MAF and then switched to speed density and gained some power (1990?) In 1994 (2nd year of LT1 on F-bodies), GM started putting on MAF. In that time, however, MAF had come a long way. Speed density setup uses manifold pressure (same thing as vaccuum--vaccuum is lower pressure than outside air), rpm, throttle position sensor (tps) reading, along with some other information to determine amount of fuel to inject.
MAF uses all of this, but also uses a mass airflow sensor in the tube from air filter to throttle bodies. This sensor tells the ECM how much air is coming in, which determines how much fuel to inject (the sensor is a heated wire that runs across the tube; as more air comes in and cools the wire, more voltage is needed to keep the wire at its temperature, the voltage tells the ECM how much air--the mass of air--that is flowing into the throttle bodies)

Speed density is simpler, MAF now yields better performance due to more precise air metering. However, as your MAF-equipped car gets older, the threat of false air comes up. False air is air that enters the throttle bodies through a leak after the MAF sensor and is not measured by the MAF sensor. Consequently, the engine runs lean.

MAF more complicated but can give better performance. MAF is used exclusively by all manufacturers now.

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91 formula WS6 305 tpi, true dual exhaust

 

If the car is stock, its not a 5.7L with a 5-speed. Yes, GM never put a 5.7L with a 5-speed. Only 305's and 5-speeds. I swapped my engine.

MAF is better than Speed Density, but Thirdgen Speed Density is better than Thirdgen MAF.


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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
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