Smooothie119

If the LB9 V8 engine redlines at 5800rpm, why on gods earth is the factory tach yellow from 5500-6000 and red from 6000 all the way to 7000?! I can understand the yellow thing cuz I've always heard that the best way to shift manually is about 10% over your redline, but why the heck does the tach even display up to 7000 rpm. I can only imagine the sound the engine would make revving that high. I'm very interested in hearing everyone else's feedback on this

smallwood

For one thing guages are more accurate closer to the middle of the measured range.

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Little red light on the highway; big green light on the speedway, hey,hey, hey!

2002 Formula, GMMG cat back /1983 Z28-sold

Smooothie119

So one should go more by the feel of the engine and the sound as opposed to the gauge? Just tryin to understand cuz when I'm gettn on it, I always get sorta nervous when I see the tach touchn the red zone cuz it would be my dumb luck that the damn thing would blow.

smallwood

No, the point is you don't want redline at the end of the range. Is it stock? If so shift at about 5500. Your engine should survive an accidental 7000 rpm buzz anyway, but don't try it. Also, why do some speedos show 200 mph? Same reason

[This message has been edited by smallwood (edited September 04, 2002).]

Smooothie119

The engine is completely stock. The only mods I have on her are as follows: a tpi airfoil, 160 thermostat, stage 2 chip from Fastchip, gutted airbox with K&N filters, 3" cat-back exhaust into a 2 chamber Flowmaster (have no idea what series but I suspect its an 80 series by the sound of it) with 2-1/2" outlets. Just wondering about the whole thing about shiftn cuz although I'd never let my tach see 6500 or more, I'd also like to maximize every shift when racing other cars. I also noticed that when I start to enter the red zone (actually I;m not quite sure if its before or as it enters that zone) I also noticed that my stock shift light begins to go bull****. However, I think my chip has probably eliminated that. I've only had the chip for a few weeks and havent had the chance to really test her out against others, but I have noticed already that the chip has changed the normal intervals that the shift light comes on. Before it would tell me to shift out of every gear when it hit 2500rpm (talk about baby shiftn, if I always folowed that thing, I'd be doin 40mph in 5th gear). Now it wants me to shift at about 2000rpm.

91RS5speed

The stock shift light is to tell u when to shift to get the best gas mileage.

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http://bitchincamaro.no-ip.com 91 RS Camaro 5-speed black w/t-tops 305 TPI
MODS: SLP cold air intake w/K&N, air foil,Accel 19 LB injectors, March aluminum under drive pullies, Alburn pro posi, Aluminum drive shaft, Random Technology 3'' cat-back, 8.5mm MSD wires, 160 thermo, jet fan swich, Custom chip with 91 vette computer, SSBC slotted rotors, optima battery in the rear, BMR adjustable lower control arms and panhard rod, Kenny Brown strut tower brace, TB bypass, no egr, no air

irocbob89

They also make the tach read 7000rpm for the people that can go that hi ive been there a couple of times, it sounds bad *** but wouldnt want to do it again.

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89' red Iroc-z
386 stroker
Mini ram, 58mm tb
30#lbs,255 high flow fuel pump
slp cam, 1.6rr
edelbrock performer heads p+p 2.02 1.60
Hooker super comps, Mufflex 4' exhaust
Ford 9' 4.11 gears, detroit locker, 31 spline
Full suspension
B&M mega shifter,2800 stall
baer rear brakes,line lock
converted to speed density
Ed Wright dyno tuned


89' red Iroc-z
LT-1, 4L60E
free mods,chip,no cat, flowmaster
full suspension

Kevin91Z

What's your definition of redline? The max rpm you should spin the engine, or the rpm where it makes the most power?
Your answer will determine my answer.

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1991 Camaro Z28
350 L98 w/ T56 (originally 305 LB9 w/ T5)
318 RWHP, 419 RWTQ
12.803 @ 108.50 MPH (1.932 60')
Member: SoCal F-Bodies
ThirdGen 4-Life!

Smooothie119

seeing that I have no intention of blowin up my motor, I would have to say the max rpm that the engine is producing power.

OrangeIROC

FYI, on the stock tachs
the LB9 305 redlines at 5000rpm and
the 350's redline at 550orpm.

Thats one of the ways u can tell what engine that you have, unless of course u switched tachs or got new overlays which changed the stock redline..

i have an LB9 305 and i got the silver faced guage overlays from Macewen Motorsports, when i ordered them i ordered the 350 tach which redlines at 5500rpm. the 5000rpm redline just looked so wussy


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1988 Camaro Iroc-Z
Medium Orange Metallic

Smooothie119

It was my understanding that if you had the LB9 with the 5spd, performance rear and a hard top, you also received the same cam as the L98, which 1)gave you a 25hp increase (215hp from 190hp) compared to the auto model (w/ the LB9), and 2)you also received the tach that redlined at 5500rpm.

Kevin91Z

That is correct, except the later years went from 205 HP to 230 HP. My car has the 5500 RPM redline, and it started as a 305.

Redline is the max rpm you should spin the engine, and the colors of the tach have no bearing on it. The RPM where the engine makes the most power is not called its redline, its the power peak. Most TPI engines will peak about 4500-4800 RPMs, and shifting around 5000 is accepted as the best place to shift.
I have no hard data, but our stock GM engines will valve float around 6000 RPMs, and shouldnt be spinning higher than that anyway. There's no need to go that high.

Markolc

I dropped an LT1 with a huge cam into my IROC. I'll tell ya, I'm VERY happy I have a atock tach that reads to 7000, cuz I shift around the 6800 range.

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1987 Flame Metallic Red IROC-Z Camaro. LT1 motor installed. http://home.attbi.com/~markolc