Baron

I'm all stock 89 RS except for K&N 14x3 open, no muffler, and a Ram heavy duty clutch...around 4500 RPM, there's a considerable lapse in power...I don't recall that happening before...what's up? The ol' girl's got 143,000 on her, but I don't think this happened even three months ago...what's the deal?

91Bird305

Well I am unsure about the LO3's power band but on the autos it shifts at 4500rpm's. There probably wasn't any power beyond there to begin with for a stock engine. What did u feel before u noticed all this?

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Eric Natzke
91 Firebird 305 TBI

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89RagTopRS

These types of cars don't have any top end power. If you had TPI, i'd be concerned. Most times like 91bird305 said it usually shifts at that point with an automatic. Your redline may be 6 grand, but there's no reason to be even near that. The only V-8 car I've driven higher than 4500 rpm was my 87 GTA, but that was a TPI 350.

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1989 Camaro Convertible
dark silver w/black top
305tbi, auto, all stock
posi w/drum brakes
Check out my site at: [URL=http://members.tripod.com/philsriceboypage/Phils%20RiceBoy%20Page.htm

Baron

gotcha Maybe I've been pushing the old girl a bit...it's a T-5, but I think this problem may be just a month old...what used to happen is I'd gradually lose power until 5 grand, when there was just about no juice left, but now it's like there's a sudden dropoff that jolts me forward in the seat...never good...and maybe it's closer to the 3500-4000 range to be honest with you...upon reconsideration I realized that's probably more like it...granted, she need a tuneup, but could it be much more than that?

Pablo

iTrader: (1)

could be a few things, I had a similar problem turned out to be faulty injectors but it could be ignition related just the same, or fuel delivery related, when was the last time you did a tune up including the fuel filter? these engines are good for 5200 shift points with open element and exhaust

the stock governers in LO3 transmissions are pathetic, 4500 rpm shift from first to second with a 700r4 will kill your track times, first gear in a 700r4 is lower than first in a t5 but second gear is like third gear in a t5, huge gear spread, if you shift low (I.E. 4500 rpm) youll simply bog the hell out of the motor by lugging it down to 2400 rpm. Manual shift it up around 5300 at least or higher if you can

and a TPI 350 runs out of breath even quicker than an L03, they can put the redline on the tach wherever they want, doesnt mean anything in terms of reality (although it probably sold more cars, higher redline means more performance right?)

91Bird305

I am just curious where it says that the L98 runs out of air at higher rpm's? Do u have a power band chart from a dyno run or something to show that?

Tas

its well known that TPI doesn't have much of a top end. The long runners are good for TQ but bad of top end HP. thats why the LT1 got short runners. By simply changing the runners they went from 245HP to 300HP in the 1992 Vette. and they only sacrificed 20 TQ going from 345TQ to 325TQ.

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-Tas
'89 Formula WS-6
[soon to be Performace Red =) ]

305, TBI, auto, 14x3 chrome flat based open element with K&N, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

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NJ SPEEDER

you may wanna try a new timing chain. with that kind of mileage the chain is definately stretched a bit, this retards the cam timing and costs power. it is natural for the stock cam to drop off at that kind of rpm. 1.6 rockers are a good stop gap to stretch the power band if you don't feel like buying a new cam.

lata
tim

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91 Camaro RS-LO3,Auto.
14.301 @ 94.39mph
The car is going street strip for next season. 13's here i come!!!!!
Edlebrock TES Headers, Cat Eliminator Pipe, Borla Adjustable Cat Back,Marche Pulleys, HyperTech Chip,Transgo Shift Kit,B&M Convertor(2000stall),Steve Spohn Rear Rig( all rod ends), Poly Front Bushings,Ported TB, 350 Injectors, Edlebrock Performer TBI Intake, Performer Heads, 1.6 Roller Tipped Rockers
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Pablo

iTrader: (1)

a retarded cam yields more top end power not less so i dont think its that, problems that arise abruptly like his are usually ignition or fuel delivery related

about the L98s power band... Go drive one.

89RagTopRS

If you lose power and it forces you forward, chances are its in the fuel delivery. I've been through my share of fuel pumps and injectors. Does your motor sputter or suddenly die at all? I went through that with clogged injectors. The other problem I had was it not starting and not getting any fuel when my pump died...again and again.

As far as my old TPI went, it was line bored and reworked for higher rpm runs. I didn't specify this. Stock ones felt weak so I modified it to death, and sold it. I personally like the TBI better with the amount of torque these have.

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1989 Camaro Convertible
dark silver w/black top
305tbi, auto, all stock
posi w/drum brakes
Check out my site at: http://members.tripod.com/philsriceb...Boy%20Page.htm

91Bird305

Ok, I will drive a stock 305 TBI and then a stock L98. I think the L98 will be making more top end then a 305 TBI.

[EDIT]
I see what u mean though Tas, you sound right. I was just curious if anyone had a dyno of a stock L98 and a stock LO3 so they could actually see the power bands.

[This message has been edited by 91Bird305 (edited January 01, 2001).]

Tom 400 CFI

91Bird, A TPI will EFFECTIVELY rev NO higher than a TBI. The TPI may make more overall power (better cam and heads) but not because it revs higher. I know this because we used to have one, and my girl friend had a '91 TPI Vette as well. Both had the best results when shifted at or below 4500 RPM. The runners are WAY too long. High RPM breathing is a dream - even with after market runners and base ($600+).

Also, you're talking about a 305 (L03) vs a 350(L98). Of course it (the L98) will have more power, but NOT because of its ability to rev higher, because it can't.

BARON check your secondary ignition system thoroughly, and do a fuel presure test while driving under a load.
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'83 Trans Am. 400 CID, 224/234 crane cam, Summit aluminum roller rockers, hand ported intake, home bored 2.09" (53mm) throttle bodies, MSD 454 injectors(75 lb/hr), Holley 255LPH fuel pump, custum modded FPR w/Vacuum port added, Edelbrock TES headers, empty cat, SLP 3" stainless steel cat back, stock ECM & chip. Borg/Warner T-5 World Class, 12" Corvette rotors and clipers, GTA 16" wheels, South Side Machine subframe connectors, 1LE sway bars, 3.45 ring and pinion, Alpine sound.
Best E.T. 13.532
Best MPH 102.24

[This message has been edited by Tom 400 CFI (edited January 01, 2001).]

Baron

Thanks fellas for all your input. It's been approximately forever since she's had a tuneup...I wouldn't be surprised if the fuel filter looks like grandma's diapers. As for the rest, I think a new cam and ESPECIALLY timing chain are really necessary, especially since the current chain's got 140k on it...I would LOVE to spend a couple months trying to figure out how to remedy a busted timing chain...anyway, I'll tune it up and get some results. Bottom line: new fuel filter, clogged fuel filter, no fuel filter, IT DOESN'T MATTER ABOUT YOUR FUEL FILTER because CHEVROLET, like the ROCK, LAYETH THE SMACKETH DOWN on allllll you rice-a-roni loving jabronis!!!!

91Bird305

Ok Tom, thanks.