Apologies if this has already been beaten to death on this board...I never visited here until a month ago

I've heard people say both sides...the '89 non-G92 cars got the "peanut cam" that debuted with the '86s, and that the non-G92 AT equipped 305s are the same internally as their higher-rated brethren. So who is right? Is the only difference with my car over a 5 speed G92 my TBI manifolds/converter/exhaust??

My car supposedly makes 190hp, whereas a G92 equipped '89 305 TPI Firebird makes 220hp...is 30hp really hiding in my exhaust system?? Thanks to anyone who can help...I've been curious about this for some time!

 

I don't know that anyone has an answer for you for an 89 car. It is a known fact that all SD 305 TPIs are identical, but for 89. The only way to know for sure is to pull the cam and check, but you can usually tell just by the numbers it will put down. A peanut cam TPI car is lucky to get near 90mph stock. A good cam 305 should be into the 90s stock.

As for 30hp in the exhaust, thats about right given my experience. I originally swapped to dual cats and L98 manifolds from the stock TBI junk and picked up 0.2s and 3mph. I wouldn't expect quite the same gains in a peanut cam car though.

 

Thanks for the quick response, Ed.

Now that you mention it, I remember the argument going on over the '90-up cars!! I guess I assumed it was the same deal for the '87-'89 cars...so has anyone here pulled their stock cam and seen for sure? My car is not going to have any engine work done for quite some time...its running way too good, and the car needs cosmetic and chassis work much much more than engine work...she purrs One of the smoothest 305s I've ever seen!

So it is possible to get back at least most of that 30hp deficit with factory-style exhaust parts? Interesting. I see I was correct in assuming the '89 car with the 305 TPI/auto had the same, restrictive TBI exhaust system the '90-up cars did. I do not plan to really modify this car at all, let alone run it at the track. All I want is to make up what the factory took away from my car...aka L98 manifolds, y-pipe, and a nice SLP dual cat and exhaust (yeah yeah, I know...big $$$ )

This is gonna be my first resto project, and while it may not be a 1LE or anything, I think its an interesting car to restore, and will be a lot of fun down the road to show and drive. Thanks for any tips anyone has on making this thing a G92 spec car in terms of engine performance. I know it has 2.73s too...I'm not concerned about that though.

 

*All SD 305 TPIs are not identical! My '91 GTA 5-spd is not a G92 car. It had 3.08s factory and single cat. I believe it has the peanut cam too. It had the 120mph/6000rpm cluster and I switched to the 350's gauges. Based on that and the fact that its not as fast as a '91 G92... I'd bet it has a peanut cam. I'll find out for sure when I pull the 305 out this summer!

 

Camshaft interchange

PN# 10111773
Camaro/Firebird 90-92 all TPI
Corvette 90-91

PN# 10066049
Camaro/Firebird 88-89 305 TPI sticks shift cars and all 350's
Corvette 88-89

PN# 10088155

Camaro/Firebird 87 8-305 4BC / 8-305 EFI, AT
Camaro/Firebird 88-89 8-305 TPI, AT / 8-305 TBI
Camaro/Firebird 90-92 8-305 TBI

PN# 14094097
Camaro/Firebird 86 305 EFI

 

Have you ever even run it at the track, much less actually spec'd the cam? If not then you are not qualified to enter this discussion. A lot of people have gone over this time and time again, and not a single peanut cam SD TPI car has EVER been found. G92 or not, all the 305s are the same.
And for exhibit B, the fuel curves in all SD 305 bins are identical. If GM was using 2 cams in these cars, there would have been 2 VE tables.
I know what you may have read and even what the tech database on this site says. They are wrong.

 

Oh, i don't know that the factory was using the small TBI style exhaust on the early low output peanut TPIs, i thought you were saying thats what yours had. You can figure that out real easy just by looking under the car to see the cat. If you have a 3" cat then you have the L98 manifolds too because the Y pipes are different between the manifold sizes (and there is no 3" cat TBI manifold Y) I really don't know for sure what a non-G92 305 A4 car would have in 89 for exhaust though.
But i wouldn't doubt too much that dual cats would be worth power even over a single 3" cat, especially with the nicer flowmaster Y on it. You get all the benefits and scavenging of duals where it matters in the front, but the clean routing of a single pipe in the back . And it's still a factory part so your resto isn't tarnished. And i don't think anybody would mind a nice catback with it

 

Tomorrow I will put up the 90-92 cam numbers. But 90-92
305's and 350's used the same cam for TPI. Throttle body
cars had a different cam.

 

Ed, thanks for basically calling me an idiot! Yes, I have run it at the track. No I haven't spec'd the cam yet either. When the motor is pulled I will spec it and prove everyone else wrong. I know this car has to be a peanut cam. It runs perfect for 150k miles and has a lot of mods. It doesn't run near as well as my buddy's G92 '91 z28 5-spd. There's no way this car has the 350's cam... NO WAY! It only ran a 9.5 in the 1/8th, but had like a 2.35 60' time. Pretty bad! It has a 9.1 or so with traction maybe. I still don't think it has that cam in it though. If it does, why would they put a 5000 redline tach and 120speedo in it factory. It never would hardly pull to that redline, much less a 350's 5500rpm redline. I also don't agree with what the GM books always say. Like they're always right. Just my thoughts....

*I HAVE read into all the tech on this discussion, and I HAVE participated in past discussions/arguments about the '90-'92 non-G92 SD 5.0's. I don't appreciate being called out like this and saying I have NO part in this conversation. Sometimes this site just pisses me off.

 

lol, your own performance tells me that you have the good cam. Of course you're not quite up there with your buddies G92 car, you're giving up gears, a 5 speed and dual cats (which i have establish is at least 0.2s and 3mph in a heavy unaerodynamic convertible) A 9.5 in the 1/8th would be a wet dream for a modded peanut cam car, and you did it spinning wheels and stock?
I'm not calling you an idiot, i'm saying that you're guessing. We don't need guesses when we know for a fact that there is no such thing as a peanut cam SD 305. Don't post a response just for the sake of it, you're just confusing the matter. Thousands of people read these boards, it's my job to make sure they are reading cohesive and accurate information.
It's nothing personal, but i don't want peope with SD 305s getting misled. Modding a peanut cam car basically requires a cam swap or you're just wasting tim. L98 cam 305s do pretty decent though, as evidenced by how easily and stock i am ghetting my heavy car into the low 14s and beyond. If you make people think they have the peanut cam then you are screwing up their ability to accurately assess what mods they should do.

 

I have a Sd 305 Peanut cammed Car.

It got the 305 HO heads on it too!

 

Gonna prove us all wrong huh? I kinda doubt it, but I'd like to see your results anyway just to confirm my suspicions that they are all non-peanut cammed. It'll be pretty easy to verify, just check the intake lift which would be considerably different.

My non-G92 91 305 TPI block doesnt have a peanut cam, and the engine had never been apart.

 

So due to the fact that the cam has a different part #, I can assume I have the dreaded peanut cam??

I thought the only difference between a 305 TPI 5 speed and AT was that the AT got a single cat, smaller exhaust manifolds and catback from the TBI cars, and that was it. Can anyone shed some light on this?? All I have is that the cam is a different part #, but to me, if the car really has the TBI exhaust on it, if I had the peanut cam too the car wouldn't even make 190hp!!

Can ANYONE with an '89 shed some light on this? Thanks for any help I can get...

 

In 88-89, the 305TPI cars with automatic trans got the small cam.
Stick shift 305's got the 350 cam. From 90-92 all TPI 305 and 350's used the same cam.

As far as I can tell.

 

Yeah, from everything I've read and/or checked, the peanut cam continued through 89. I'm not getting involved in the 90-92 discussion, for I am not worthy and fear that Ed might strike me down...

 

twincat roc
I have an iroc that I bought new in 89, it has the g92 option, twin cat exhaust, oil cooler, five speed, no electric power options, only ac and radio. Car weighs 3300 lbs
and has the 145 mph speedometer. Have read several times that the lb9 engine in this car shared the l98 cam but only know what I've read, however the tach redlines
at 5500 and l98 friends vettes redlined at 5000, go figure.
Car has 3.45 rear gears.
Responding to this because of the request of someone asking about input from an
eighty nine owner. HP on this engine is suppose to be 230 I believe. It is though getting info on these cars.

 

but that was nearly 12 years ago

04-25-2002,

May have got a answer by now

 

I got a 87 305 tpi, i dont have G92 (dont really know if it make a something) all stock no mod with a 2.73. But this thing would easy go at 120mph, so peanut cam ?? dont really know... plz help