GTA50

that my '88 GTA with the LB9/MM5 actually has the "305" cam?

My letter from GM Vintage Vehicle Services lists my enigne at 190 hp, yet the documentation from this site and GTASourcePage give 215 hp.

So, who's right and how do you prove it?

Drew

iTrader: (58)

Does it really matter? What difference does it really make?

Short of trusting one printed material over another (often multiple GM documents for the same make/model car will disagree about the HP rating), you could tear the engine down and look for identifying codes on the camshaft. Or you could pull a valve cover and use a dial indicator and a magnetic base to measure the cam and then compare that to printed materials.

Either way, does it really matter? Being a 5spd LB9 it should be the higher output version, but what is that really worth? The numbers are extremely arbitrary anyway.

eseibel67

Those historical services can't posssibly be aware of every little nuance such as the LB9/T5 combo gets the L98 cam.

If the motor is untouched, it's 215hp version.

GTA50

The actual engine output is of no great significance to me. What I was really interested in is how would the decision be made. So, what was the trigger point. The LB9 was obviously available with the 700r4 and the MM5. What made the difference in output?


Probably aswered my own question, but the fun aspect is that this weekend I had to replace the clutch on my '91 305/5-speed. The flywheel is different from my '88 GTA. I thought they should be the same and interchangeable. So....some research, and correct me if I'm wrong, but the LB9 flywheel is apparently lighter than the LO3 flywheel. Definitely a different appearance as the LO3 flywheel is full circumference while the LB9 flywheel only matches the clutch diameter. The refernce pin matches up exactly.

So, what I surmise is that a TPI/MM5 is what was the trigger and as a result, the lighter flywheel, better camshaft, etc. was all coded for.

This is what I would like to confirm. The other interesting aspect is could this combo go the other way and end up with a flexplate rather than a flywheel.......

topduarte

iTrader: (8)

I thought the 190 HP version had the 110 mph speedo and the 230 HP version had the 145 mph speedo.

And IMO, it does matter. Just my $.02!!!