I was just wondering how I can find my redline. built my engine mildly from top to bottom. something was done to every component in the engine. I am almost positive that my redline has changed from my stock tach redline of 5k. Even if it means my redline only has increased by 250 rpms' I would still like to know. Right now I am sticking to the 5k redline to be safe but, I would like to know exactly how to figure out my redline.

Thanx in advance

 

with butt seat dyno red line is when engine stops pulling, usually long before it'll stop revving

 

What ede said and also, Did you replace the cam? if so what RPM is the power range rated?

 

when the valves float or something comes out the bottom, that's just a bit too high. you could also just have it dyno'd.

 

well.. depends on exactly what you have done to it...

it the bottom end is still pretty much stock, i wouldnt go past 6500... even if the engine could pull past there..


i would pretty much shift when it stops pulling... unless somthings not matched right with the combo.. or stop if it sounds like im straining it too hard...

most likely if its a street cam, you'll past the hp peak, or the valves will start to float, and you will want to shift... you just kinda feel it... *shrug*

 

80-84 block
4 bolt
40 +
crank -10 on rods & mains
clevite 77 tri metals
aluminum i beam rods
aluminum dished pistons
heads are stock with 1.94/1.5 valves
cam is unknown. I have the casting numbers that are found between the lobes but I did not find any other numbers anywhere on the cam. I don't have a dial. I don't have a wheel but, just by looking at it you could tell that it was definitely a lift cam. lobes were not very wide at all. but they were taller. If I had to guess i would say that the lift range was about 3/8" and duration was in the .180-.200 range.

But, does anyone know the formula to find it?

 

I always would correct my buddies when they think they moved their redline higher when they change cams. There's much more to an engine, namely the tightness of the bottom end and the valvetrain. Compession has alot to do with it too. It's been my understanding that the mechanical redline is the point that you need to call AAA to come get you. I can't see how there would be any formula for this, at least finding out before it's too late. My rule of thumb is where the engine stops pulling, as mentioned already. At this point, when the power curve begins to fall, your engine is in danger. You can experience the same danger if you're one of those idiots who sits in their driveway revving their motor while in neutral because it sounds cool. When you immediatly cut the fuel supply off from a motor spinning at say 5,000rpm, the force no longer comes from the combustion chambers, it's coming from the momentum of the rotating assembly. If something's gonna give, this is when it will happen. Refrain from doing this with your aluminum rods. Going back to your redline issue, we need to know specs on your valve springs, keepers, locks, guideplates, studs, rockers material of valves etc. Dished pistons doesnt help much, although it symbolizes low compression ratios. Someone with a desktop dyno program could probably whip some quick answer up for you if you can tell them some cam specs.

 

Unfortunately, I am one of those idiots that revs up in the driveway but, only when my friends are around and they want to hear it. And even then I only give a quick vroom to about 3k-3500 not a wipe open wail where the motor sounds like it's sayin, "here I go say goodbye".

To be honest, the car still feels like it's pulling strong at about 5500-6k. I brought it up that high on accident a couple of times.
The old redline on my 305 was 5k and that had a 2 bolt main. This motor has a 4 bolt so I figure at the least, I have some cushion after 5k. not to say it's recommended to bring it past 5k even on a 4 bolt main but, I feel that if I accidentally let it wind out at 5500 with the 4 bolt, I can say oops. but, if I were to try that with the 2 bolt, I'd be saying what I said. OH S*IT!!!

Unfortunately without a dial and a wheel, I can't measure my cam so until I can measure it up, (which will probably be next spring as it's getting cold here in chi-town and I don't have a heated garage. If it's not necessary, it waits till spring.) the cam will be a guess and inaccurate.

As far as materials on the heads are concerned, as I mentioned they are stock. bone stock. which means a whole lotta steel. The only reason I used these heads on rebuild was because they were factory measured at 1.94/1.5. I felt that these heads would give me a little crisper response on the pedal over the 1.84/1.5's that I have.

Being broke sucks. You gotta work with what ya got.

 

Don't let the 2 bolt v 4 bolt fool you, any engine builder will tell you that for street use it won't matter a hill of beans (unless he's got one he's trying to sell you). 4 bolt mains are a little more friendly to high revs, but I am talking NHRA and NASCAR type scenarios. In fact, the infamous 327 and 302 were 2 bolt mains, as well as most factory roller cam engines. I know you've got a 4 bolt I just like to sound like I know what I'm talking about when I have a chance, lol. I got my best times with my stock 305 shifting at 5,500rpm. I don't know how to put it other than just take your chances and have fun. I know how it is to be broke, right now I'm in a situation where I've sold my cars and I'm babying a 222,000mile chevy truck untill next spring. You can always have faith that someone will be selling a running 350 for cheap at the exact moment you blow yours. So I say rev it as high as it still makes power but know that you're taking your chances every time you surpass "grandma mode"

 

you're not supposed to rev the engine to redline on your driveway? i thought it automatically did something and held it at 5000..then again i've never tried

 

redline is simply the max recommened RPM. wherever you feel your motor stops pulling hard should be your redline, because you shouldn't ever need to go past that RPM. so if your motor stops pulling aroung 6100, shift at 6100 and never take it above that.

 

you can take it past the redline on the tach??? never knew that

 

I think your thinking...(ouch) of a rev limiter. I don't know of any thirdgen that came stock with a rev limiter but, they can be added on. So if you didn't put it on, it probably doesn't have one.

 

Oh yeah. start in 1 and hit it. watch your tach. but, don't take it too far past red.... y'know what scratch that whole phrase. you can't do it. nope it can't be done. right guys?! tell this guy it can't be done (before he blows his motor up)

 

anyhow, I think I'm gonna take it to a speed shop. the gauge in my shop only goes to 120 horses. It's an old dyno that was installed in the 60's or something. Anybody know approx. how much a dyno test costs?

 

Around here it runs about $100.00 an hour with a minimum of an hour.

 

holy crap I could go rent a mobile dyno for less.

 

no you couldnt.



if you go find a dyno day, it can be anywhere from free to $70 or so..... depends...

when i was in dallas, i would goto LS1.com dyno days for free.... i was the only 3rdgen there... and the lowest output car... but hey, i got a baseline for my L03....


now when im done and dyno again, atleast i can see how much i gained..

 

Just keep your foot in it in first gear and don't stop until you hear a bunch of funny noises and stuff starts to break. That's your redline.

 

Thats what I did. We got a bunch of friends together and went. It worked out to about $30.00 each.

 

that's how I did it before. It only worked once though. I thought that the red section meant you were in turbo hyperdrive warp mode. According to my buddy though, the red section is meant for people how want to be cool and show everyone on the road what a motor looks like in cubic inches... 305 individual cubic inches. Go figure.
I never saw a motor scatter but in real life I saw a pushrod shoot about 50 ft. into the air and one time at the track during the amatuer stock car enduro ( not the street enduro ) I saw a fan blade come shooting out of the side of a fiberglass fender..heh heh it was pretty cool. like a razor blade. bounced off the ground and shot into the fence and stuck there. lol. scared the crap out of the lady sitting in front of it. she started cryin and stuff. She could've gotten killed or seriously injured but, because she didn't it's funny. ROFL