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Don't know much about the LG4, but the difference between the LO3 and LB9 is mostly due to fuel delivery (TBI vs TPI)...maybe slight differences in exhaust manifolds and cam
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92 Camaro RS LO3, 5-spd, T-tops
Performance:
SLP 1 3/4" Headers (Coated by Paul Barry Motorsports), Flowmaster Catback Exhaust, Fastchip Performance PROM, Centerforce Dual Friction Clutch, Xact 8mm wires, Open Air Element w/K&N Filter, Z28 Grille w/aftmkt fog lamps
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, Edelbrock performer intake
the Lg4 is only rated at 145 hp i believe becuase of these reasons, very restrictive air intake, small camshaft, 8.5 to 1 compression, very small exhaust manifolds.
I think it was designed more for economy than performance.
The cheapest 305 to buy, and the easiest to put in and get good hp out of is actually the boat anchor of the group, the LG4. With a good aftermarket intake, mild cam, and headers the LG4 will put out around 240-250 hp easy and the cash outlay will be minimal. Not a bad choice if you are on the cheap and have to get a 305. I would definitely try to steer you toward getting a 350 though, even if it is relatively mild for now. Because you're switching engines anyway and you'll be much happier in the long run w/ a 350...
Seriously man do not mess around with a 305. A 350 is simply a superior motor in every way. 'Rebuilding a 305' should be an oxymoron.
That being said... the later LG4s and the L03 are roughly equal in performance. Low 16s in the T5 cars, mid 16s in the 700R4 cars.
The better LB9s (87-89 T5 cars and all 90-92 cars) are closer in capability to the 350 TPI than the other 305s. The small cammed 86-89 305 TPI auto cars are high 15/16 flat cars. The difference in performance vs the TBI and LG4 cars is due to better cam profiles in the 305 TPI, better heads, and (usually) a better exhaust, as well as the better flowing TPI unit itself.
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91 Trans Am WS6
Bright White
5.0 TPI auto
Flowmaster 3" 2 chamber catback
Trans Go shiftkit
2000 stall converter
Built on Wednesday
[This message has been edited by MrJ (edited May 01, 2001).]
The LO3 and LB9 heads are acctually quite different.
I have 2 friends, one has an 88 IROC LB9 the other an 89 RS LO3, both manuals. My friend with the 89 RS converted it to TPI, has full exhaust, SLP cam and 3.73 gears. The one with the LB9 88 IROC has full exhaust, 3.70 gears, and a ROD 6 speed. The LB9 IROC can wipe the floor with the RS, and both are TPI and modded closely. Now, I know the 6 speed in the 88 IROC helps out, but the heads on the RS have to be different. The IROC runs high 14s and the RS runs mid 15s, both up here at 6000 feet of course. So, the LO3 heads have to be a good deal worse than the IROC heads.
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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End
Yeah I gotta say I believe the 305 TPI would run way better than high 15's/flat 16's. Probably high 14's/low 15's. I know Monte Carlo SS's had 305 HO's with carbs and they run mid 15's stock.
