I just want to be certain which engine I have..

a couple codes

GU4 : AXLE REAR, 3.08 RATIO
G80 : AXLE POSITRACTION, LIMITED SLIP
LB9 : ENGINE, GAS, 8 CYL, 5.0L, TPI, HO
MM5 : MERCHANDISED TRANS, MAN 5 SPD PROVISIONS
M39 : TRANSMISSION, MAN 5 SPD BORG WARNER, 77MM, 2.95

The car is a 91 z28 convertible.. The tach redlines at 5000

 

Since you have the 5 speed, that means you have the 230 hp 305!

------------------
1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: LT4 Hot Cam, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Gutted Catalytic Converter, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, Fully Ported TPI Plenum and Base, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

 

205hp.


The 230hp LB9s in 91-92 redlined at 5500. Which also included the dual cat option.

------------------
91 Formula
305 TPI 5speed
1LE/G92/WS6
K&N, SLP airfoil, ported/polished plenum, March pulleys, TB coolant bypass,Crane AFPR(47psi),Crane Gold 1.6rrs,MSD coil,MSD6AL, Holley 9mm wires, fastchip, Bosch O2sensor, SLP headers & catback,short shifter,3:73s w/Auburn posi,160* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

[This message has been edited by theformula (edited January 17, 2001).]

 

looking at the RPO's it looked like my car We have the 205 horse. I have mine up to about 230 with mods though.

Jeremy

------------------
92 Z conv
5-spd B&M shifter
home-made ram air, air foil, headers, no cat, TB bypass, kevlar pads, slotted rotors, BMR panhard, alston SFC, 3.42's
when it warms up Edelbrock STB maybe springs

 

I have the engine that would have been in your car in mine, it was out of a 91 with the posi and stick. It may be rated at 215HP... but it doesnt have the so-called 'peanut' cam, I checked the lift and duration myself. I kinda 'borrowed' the format from comp cams here, hope it shows up right:

Actual 91 215HP TPI Cam specs (format stolen from compcams.com :

ENGINE: CHEVY SM BLK 305-350
INTAKE EXHAUST
VALVE ADJUSTMENT HYD HYD
GROSS VALVE LIFT .413 .428
.006 TAPPET DUR 259 265

VALVE TIMING OPEN CLOSE
AT .006 INT 8 BTDC 71 ABDC
EXH 61 BBDC 24 ATDC
THESE SPECS ARE FOR CAM INSTALLED
AT 119 INTAKE CENTER LINE

INTAKE EXHAUST
DURATION AT .050 202 207
LOBE LIFT .2750 .2850
LOBE SEPARATION 115.5

It may be that the dual cat added 5 or 10HP, not sure where the other 5-10 came from, maybe something in the exhaust.

 

Didn't the 230hp version come with 3.42 gears?

 

The 25hp difference is due to the lack of dual cats, a small Y-pipe, small (possibly TBI sized) exhaust manifolds, and a 2 1/4 inch catback.

------------------
91 Trans Am WS6
Bright White
5.0 TPI auto
Flowmaster 3" 2 chamber catback
Trans Go shiftkit
2000 stall converter

Built on Wednesday

 

That doesnt work for 90-92 cars. The 230 HP engine was an option, with the G92 package. If you have dual cats, thats the 230 HP version. If you have a single cat, thats the 205 HP version. Since you have a 3.08 rear end, I'm guessing you have a single cat, too.

------------------
West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

Sorry to Necro a preposterously old thread, but I dug this up with a search and thought I'd add some information that might be of use to others searching.

Anyway, since many of our cars have had the original exhausts and cats come and go by now, it may be difficult to tell whether you had the 230 hp or the 205 hp version.

The RPO code for the dual-cats (and therefore 230 hp), is N10. Look for that in conjunction with LB9, and it will tell you which LB9 you have.

Also, my transmission codes (for a '91) are MM5 and MK6, not MM5 and M39. M39 seems to be used with the 3.08 axle, while MK6 corresponds to the 3.42, which is GU6. I'm not sure if the difference between MK6 and M39 is "world class" T5 vs. not, or if it's the same code for a different transmission.

Anyway, point is, for clues as to how many ponies your LB9 had originally, look for N10 and and GU6 (and in the case of 5-speed cars, MK6).

 

I'm thinking that the 205 was with an Auto Trans single CAT, and 230 HP was with a Manual Trans with dual CATS.... I suspect they have the same engine, same cam.... You would loose about 12 HP in the Auto Trans -vs- Manual, and gain about the same amount with the extra CAT setup... That would account for the 25HP difference.

My 1987 LB9 5-Speed G92 is the 215 HP engine with a single CAT. Your car (since it's a few years newer) may have a slightly different cam than mine came with, but I suspect it's so similar that it would make no measureable difference in HP.

 

Hello mnorton!!

I have a 1987 Camaro IROC-Z with LB9, 5 Speed, 215 HP, single cat, but I don't have the G92 RPO. My car originally came with the BorgWarner 9 bolt posi with 3.45 gears, however some D***A** changed out the rear end for another BorgWarner 9 bolt posi with 3.27 gears!! How come I don't get the G92 RPO? Yet I have all the parts?



To the OP of this thread, I don't mean to hijack your thread, but I had to ask!!! Also, based on the info that you gave in your original post, you have 205 hp!! You can check that on the home page of TGO, under Camaro Tech Data for 1991 Camaros!!

 

I always thought that the five speed cars got a different cam then the auto cars, hence the hp difference. I thought also that the dual cats were only good for 5 hp (225 vs 230). If I recall, the original tpi 305 had the corvette cam making 215 horse in 85. The following year it got the 305 cam making 195 horse with the auto (all that for 1 mpg extra). When the stick 305 tpi's came out in '87, they got the 350 cam and higher rating (220, i think) while the autos kept the 305 cam. Someone correct me if i'm wrong, please.

 

Hello donnis618!!!

Iroc's had 215 HP from 305 auto in 1985, 190 HP from 305 auto in 1986, 190 HP from 305 auto in 1987, and 215 HP from 305 manual in 1987. All these had single cat exhaust. The HP difference between the years was attributable to just a cam change.

 

its the 205 hp. it my car exactly. single cat 110 gauges 5 speed and 3.08 rear. g92 got the 145 gauges dual cats and the 230 hp rating with 3.42 rear.

 

Did some research, The 88-89 cams where different then 90-92 cams wich had less duration and little less hp on 90s models.

 

I can't speak to 1990, but 1991-1992 manual transmission equipped cars with N10 got the L98 cam and a slightly better exhaust to reach 230HP. So it wasn't 100% cam changes between years. Exhaust factored in as well.

 

Old Thread, I know... but I want to clarify...
G92 is, or is not an RPO code?

My 91 TPI 5 Speed has all the codes for 3.42 GU6, N10 Dual Cats, C60 for AC, KC4 - Engine oil cooler, no J65 rear disc, and the Speedo redlines @ 5500..... I'm pretty sure it's the 230 hp, but didn't see G92 RPO code anywhere....

Rafael