I have noticed the 86 z28 lg4 is 10 hp more than the berlinetta lg4.. I have not found out why this is. Is there anybody that could shed some light on this?

 

probably the air intake design.

 

well, the intake seems the same at first glance.

 

1987 LG4 equiped Z28 and IROC models, got 170 h.p. due to a less restrictive exhaust.

The optional LG4 for Base Sport Coupe and LT had 165 h.p. 10 up from 1986 LG4's because of a new roller camshaft.

 

I need to get it on ramps and measure the pipes. My 86 is rated at 165 hp, and the 86 berlinetta is rated at 155 hp. nothing that's gonna suck the wind out a ya, but besides this, none of the right ups, and spec sheets explain the difference. By the by, I would like the passenger side scoop for the duel snorkle air cleaner. I haven't had any luck yet finding one...

 

Yea that's about right. Now remember, the reason power went up in 1987 was due to the switch to a roller cam and rockers. Berlinetta's were just supposed to be luxury cruisers. Not even a rear stabilizer bar. If you wanted to, you could go with the dual cat set up or do what I did and go with a single 3" exhaust.

 

The z28 lettering on the side of the car magically adds 10 hp. Actually the HP ratings on both were underrated anyway for insurance purposes so the Z28 is just less underated.

 

Did you replace your y pipe?

 

Do you know how much the LG4's were under rated? I believe mine is bone stock, but I may have a HO cam and not even know it. I am certain my tranny has had a shifty kit put in it. My tv cable is hooked up properly, but it has a nice firm shift 1-2 and 2-3.

 

Some of the car mags put them on chasis dyno and were getting 5 to 10 more hp than the flywheel rating at the rear wheels. Figure about 20%

 

My LE9 305 Van dyno'd at 174 RWHP @ 4,600 rpm, STOCK and 255 ft/lbs. The engine was completely stock, except a replacement high flow catalytic converter at the time.

As far as the difference in HP/TQ between years. The ECMs improved from the early years to the later and may have had hotter spark advance settings after the introduction of the ESC and Knock sensor. I think the 85 year model introduced flat-tops in the LG4.

 

Headers, Y pipe, large 3" cat. Still working on getting the rest of the system.

 

What was the HP rated by GM? Yes they did go to flat tops in 85, although the 85 LG4 for iroc or z28 is 155 hp and in 86 it is rated at 165 hp for z and iroc z. in 88 I think they went to roller cam, and a dish piston for what ever reason.

 

1987 was the last year for the LG4 and replaced with the 5.0 TBI engine in 1988 which was rated at 170. 1987 all engines got the roller cam and LG4 was rated 165 for SC and LT and 170 for Z28 and Iroc.

 

Wow, these numbers are depressing for our Camaros, lol.

 

By today's standards, yea the numbers are low considering most four cylinder cars have that rating. At the time, those were decent numbers. But...at least our engines are easy enough to modify and get more power and there are A LOT of engine choices now that we could drop into our cars.

 

also as madden 55 said, these engines were under rated as far as hp is concerned. I am not surprised. I thought my 305's were kinda torqie. I am from the old school stuff. I had a charger rt w/440 mag. I know what power is (was). The power I am getting is decent for 86, and 92..