ohiothirdgen

What was the difference in the regular LB9 and the "HO" LB9? Which cars got which? How can you distinguish the two?

LAFireboyd

iTrader: (3)

Officially, the "HO" engine was the carbureted L69 engine, available from '83-'86. There was never an officially-designated "HO" LB9 engine, even though some websites show such a distinction.

However, if there would've been such a thing as an "HO" LB9 engine, then it would make sense to think it would've been to show that there was a difference between the LB9 with a manual transmission and the LB9 with an automatic transmission.

The LB9/manual had the same cam as the L98, so it was more powerful than the smaller-cammed LB9/auto, therefore making the LB9/manual engine an "HO."

But I believe the "real" unofficial theory is that since the LB9 was the optional 305, all LB9s were designated "HO" simply to show that the car didn't have the standard 305 in it.

But in reality, again, there was no official "HO" LB9. So what it might mean and why some sites label it as such is unknown. There might even be more explanations, too.

ohiothirdgen

Thanks. I labeled it as the "HO" version for the obvious power difference between the two. I am looking at a car and was reviewing the specs and noticed that there was a difference in the two but was unsure what the difference was. Thanks for answering my questions.

my82roc

iTrader: (101)

Ive also heard about different versions of the LB9 motor.I read that certain cars had a better cam and you could tell which ones they were by looking at the tach.A regular LB9 had a 5000 rpm redline and the one with the better cam had a 5500 rpm redline.I know that the LB9 5 speed cars and L98 cars all got the 5500 redline tach but the other day I found a 1985 Iroc VIN code F LB9 Car with an auto trans in the junkyard and it had the 5500 redline tach.So I would assume that car had the better cam LB9 TPI Motor

rockit

iTrader: (3)

wonder how tat sort of stuff affected digital dash gta's?

okfoz

1) ALL GTA's would have had the better engine over the Trans Am. There are exceptions...

For the most part 305/M5 GTA's and Formulas would have gotten the 3.42 or 3.45 gears. THere are exceptions but there should not have been.
2) Since the dash was digital there was no difference in them from one engine to the other.

3) the LB9 has been described in some Dealer literature as the HO engine, but there was never a Badge which denoted it on the car. the "HO" Engine was the L69, a 305 4BBL from 1983 - 1986.

4) I am not 100% sure but I believe all LB9/A4 cars got the lesser "Peanut" cam, there was nothing I have ever seen to the contrary.

John

a mack6

iTrader: (1)

In 1991/1992 almost all of the LB9/A4 cars got the good cam (ie: the L98 cam). The 1991/1992 LB9/A4 cars still have slightly less HP than a LB9/M5 car because they got the smaller exhaust but they have the good cam. I remember reading many topics on this this site where owners of 91/92 LB9/A4 cars pulled the cams out and found out they were indeed the L98 cams.

okfoz

You are correct, actually the cam was the same in 1990 as well. I should have stated that " IIRC there was not a Cam option on the LB9/A4 for any year."

Interesting The cam that was used in 1990 + was actually less agressive than the 1988 & 1989 cam.

John

a mack6

iTrader: (1)

John, thats interesting. Do you mean that the 88/89 L98 Cam was more aggressive than the 90-92 L98 cam (that also happened to be used in LB9s)?

LAFireboyd

iTrader: (3)

Interesting, the "Camshaft Data" on TGO's page below

https://www.thirdgen.org/tech-data

supports John's first statement, that all '90-'92(actually, '86-'92) LB9/autos had the peanut cam. True, TGO's data pages aren't always correct, but they usually are. So I'm wondering where the info came from that said LB9/autos got the L98 cam in '90-'92.

The data also shows that '90-'92 LB9/T-5(non-G92) cars got downgraded to the same peanut cam. So maybe you're seeing that "same cam" and thinking the LB9/auto got bumped up, when it was actually the LB9/T-5(non-G92) that got bumped down--if the data is correct.

But the only '90-'92 engine the data shows with the L98 cam(besides the L98, itself, of course) is the LB9/T-5 with the G92 option.

'90-'92 LB9/autos did get the smaller exhaust, though, like mack mentioned. So the LB9/T-5(non-G92) cars probably got the smaller exhaust, too.

The page also confirms that the '90-'92 L98 cam was smaller than the '88-'89 L98 cam. The later cam reverted back to a profile similar to the '87 L98 cam. I'd guess it had something to do with tuning or emissions with the new Speed Density... or maybe with both issues.

a mack6

iTrader: (1)

All of the "official" information says that 90-92 LB9's got the peanut cam, but there are quite a few topics on this website where people tore apart their 90-92 LB9/A4's and found the L98 cam in there. To my knowledge, no one ever pulled the peanut cam out of a 90-92 LB9/A4.

okfoz

Actually the Parts & Illustration catalogs have the following:
MK6 - Manual Trans
M39 - Manual Trans
NM8 - Export
NB2 - Calif Emissions
NA5 - Fed Emissions

We all stand corrected...

Attached you will find the 1995 Parts & Illustration catalog as found from Chevrolet (Right). AND you will find the Late 1991 version for the Firebirds (Left), Both of them appear to be the same at a glance BUT What is possibly the most interesting fact about both of these is the 1985 & 1986 (Export) cams for the LB9 was different for camaros and Firebirds...

John

LAFireboyd

iTrader: (3)

Those two pages confirm or, at least, agree, that all LB9s(manuals and autos) got the same cam as L98s in '90-'92.

But there are some other interesting things I noticed:

Each page consistently shows that '83-'86 L69s and '85 LB9s all received the same cam during those years(which we knew), but the part number shown on each page is different for them. The Pontiac page shows 14088843, but the Chevrolet page shows 12523897.

Other than those two part numbers, both pages are consistent with their part numbers.

So all export '86 LB9s(manuals and autos) got the same cam as the above-mentioned engines(the part numbers being page/company-specific, as John mentioned), rather than the peanut cam. That was cool for the exports.

And all export '87 LB9s(manuals and autos) got the L98 cam, which was very cool for the exports, too.

So it looks like the export cams weren't "downsized" during those years like the cams in some of the US engines.

Kevin91Z

iTrader: (1)

The thirdgen tech data was never updated to reflect the new data we found that the manual trans 305 TPI's never got the peanut cam. As far as I know, only the 88-89 305 TPI automatics got the TBI peanut cam. All the 305 TPI 5-speeds have the better L98 camshaft. However, as mentioned above, the 89-92 305 5-speed TPI's could come either with a single cat 2.25" exhaust (rated at 205 HP) or the dual cat 2.75" exhaust (rated at 230 HP).

gearhead0384

iTrader: (7)

What about 86 and 87 auto LB9s? They have a the worse of the two cams also.

Kevin

okfoz

I guess I should point out that although those are the replacement parts, the original parts may vary. I know Springs for example actually had more different rates and stiffness than what is in the books as replacement. In many cases GM offered only a selected amount of parts as replacement BUT in reality there were more than that which originally went on the car. Another case in point is VanNuys California cars apparently got LOF (Libby Owens Ford?) Glass and the Norwood OH cars got PPG Glass.

So although there is one cam as a replacement that may or may not have been entirely the case. We can speculate and we will conclude eventually that is the case but I needed to point a few things out.

John

Kevin91Z

iTrader: (1)

'86 TPI got the flat-tappet LG4 camshaft and there is no question about that.
'87 TPI I have seen people on these boards claim to have either camshaft in their car, so I dont know which is correct.

gearhead0384

iTrader: (7)

I thought I really new this stuff well and I am confusing myself. My old 86 IROC had center bolt valve covers on it but I know I that 87 was the first year for roller blocks. I have not had the car in a while and did not really think about it for a while.

Kevin

LAFireboyd

iTrader: (3)

1987 was the changeover year. "Early" '87s got '86-style engines, and "late" '87s were like '88-current engines. To order certain replacement parts for an '87, you have to know which engine you have. Mine was built in December '86, and it has a "late," current-style, engine.

The November '86 issue of Motor Trend features an '87 Camaro Convertible(with pix of it being chopped) and an '87 Formula. Both cars have "early" engines('86-style). The 'vert has an automatic, and the Formula has a 5-speed.

I don't know when during '87 production the change took place, or if there's even a recorded date. It was probably just whenever GM ran out of '86-style engines.

Guest

Scratch that.