redline?

[zed]

It might sound strange, but I don't like to rev my motor hard. Not in my Nissan or any other vehicle. My old man used to say 'Don't rip the guts out of it'. Also, now that I have re-built a few motors, I know that one bolt working loose can trash it...

[Guest kamakazi620]

It might sound strange, but I don't like to rev my motor hard. Not in my Nissan or any other vehicle. My old man used to say 'Don't rip the guts out of it'. Also, now that I have re-built a few motors, I know that one bolt working loose can trash it...

 

I have 2 words for ya Torque Wrench and Locktight!!

[bonvo]

It might sound strange, but I don't like to rev my motor hard. Not in my Nissan or any other vehicle. My old man used to say 'Don't rip the guts out of it'. Also, now that I have re-built a few motors, I know that one bolt working loose can trash it...

 

runn a deisel then you will be happier gas motors like to rev for the most part to make power

[Guest 510kamikazifreak]

I have 2 words for ya Torque Wrench and Locktight!!

 

 

Thats 3 words :lol:

 

I have 2 words chicken shit :P

 

L motors can rev!

I have spun a few L16-18s to the 7 plus limits :o

No harm done ;)

[Dawa]

alright. i realize im bumping a 2 year old thread, but id rather do that than start a new one.

 

ive been wondering the redline of my L16.

more importantly, i want to know the highest, SAFE RPM at which i can run at (on the highway, for example)

my 73 only has a 4speed, and the majority of my traveling is via highway.

it sounds silly (especially after reading this thread) but i dont like going above 4000rpm.

but that was more of a self imposed limit, erring on the side of caution since i didnt know the actual limit.

i would be happy if i could go 4500 or 5000rpm. but even at 4000rpm its super loud so i doubt id go much above 5k even if its safe.

 

btw, i do have a 5 speed swap in my plans (and an L20), but that wont be for a little while.

[datsunaholic]

Put it this way...

 

US Speed limits in 1973, prior to the OPEC embargo, were typically 75 MPH. A 620 could do that easily. As could the PL521. You'd be pushing luck with a 4.88 J13 powered truck though.

 

An L16 in GOOD condition has a redline just over 8000RPM. You'll never get there on level pavement in 4th gear. Max horsepower is at 5600 RPM, so the falloff + increased aero drag means you can't get there on a stock engine. 6K is safe. With stock-ish size tires, you're only doing 3500 or so at 60. 5K is 85MPH, good enough for a speeding ticket just about everywhere (including California).

 

It's loud because it's a 4-cyl, it's turning over 4K, and the 620 has all the sound deadening of a grocery bag.

[Dawa]

lol, i know why its loud. but i appreciate your answer, especially so late at night and before i have to drive to work tomorrow

[DanielC]

This is what I think for a Datsun L-16 or L-18 engine, the only two Datsun engines I have lots of experience with.

 

Back in the day, I used a 521 to tow a light horse trailer with two full sized horses all over the Pacific Northwest, and also my boat I had, a 16 foot Tahiti, with a 135 Mercury in line 6, locally to the Willamette river, and also I towed the boat in the summer on 1983, working a travelling camp from Portland Oregon, to Lake Shasta, and down to Bass Lake in California, near Fresno.

 

The RPM range I would use when trying to maintain normal speed, 3 to 5 K RPM. When wanting to accelerate, 4 to 6 K RPM. The most common times I would go above 6000, was in second gear, because of the big drop when going into third with a stock four speed.

On one trip down the Columbia gorge, with the wind really blowing up the Columbia gorge, and an empty horse trailer, I had to spend over two hours at 5000 RPM, and about 35 MPH and very close to WOT to maintain progress.

 

I used 6500 for a yellow zone, and 7000 for a red line, because that is what a tachometer in a 240Z was. I think that is also the factory limits on the tach in a 510, that had a factory tachometer.

 

It was stated in an earlier post the highest stress point in the engine cycle is near the end of the exhaust stroke, as the crankshaft is slowing the upward piston down and is getting ready to reverse its direction, and pull the piston down for the intake stroke. That is true. Also right before TDC, the intake valve is starting to open, as the piston is moving closer to it.

 

There is nothing magical about 6500, or 7000. But stresses increase on engine parts with the square of the engine speed. An engine running 4,000 RPM has four times the stress on it's components as the same engine running 2000 RPM. Double the engine speed again to 8000, and you have 16 times the stress as the engine running 2000 RPM. I know you should not run a Datsun engine at 2000 RPM with a lot of throttle, you would be lugging it. But in my opinion, you should not run a Datsun at 8000 either.

[Dirttrack510]

Thats 3 words

 

I have 2 words chicken shit

 

L motors can rev!

I have spun a few L16-18s to the 7 plus limits

No harm done

My Race Wagon is testimony that you can rev the crap out these engines and they just keep going. 3 years of revving my old 200,000 mile L16 on a race track for an average of 6 miles a night at 7K plus every weekend 30 weeks a year and I just pulled it out (still running good) to install my new full race L16 that I plan to rev up close to 8K every weekend. :devil:

[doomdatsun]

I revved my L20a (six 2.0) to near 7700 RPM in neutral.

at road I reached 5K only, cause it starts rumbling like an earthquake, the bad trans helped as well in that problem, L20a low end torque is nothing, but when revved hard to 4.5K and above you will have a strong torque line, I was thinking about how much I can take to but was afraid I would destroy it, although the rear diff is 3.889 but I can't feel it reaching 60MPH fast enough? I can't read speed as speedo is dead

[scooter]

When i went back and fourth with the 620 to calgary it would run at 5-5500 pretty much continuously for 6 or 7 hours... That was with the l16 and later the l20b.

 

The slip yoke welded itself to the bushing and exploded the tailshaft housing on the tranny though...

 

The lz23 has arp bolted l20b rods and gets buzzed to 7500 frequently, but highway pulls hasnt seen much more than 6500 in 5th gear.

That engine probibly sees less sustained high rpm than the stock motors did, due to a 5 speed..

[G-Duax]

The Kamari built L-series engines in Japan turn 10k.

It is all about how much $$ you want to throw at them.

You want to turn faster, you have to buy better parts.

[Stoffregen Motorsports]

There is an exponential relationship between an engine's RPM limit and the cost. The same goes for engine wear and lifespan.

 

10K is an optimistic number for any L series unless it's a L13, L14 or maybe L16. I have built a few national championship GT4 L16's and they went to about 9600 RPM's

 

Ironically, the pushrod A series is better at big revs than an L motor. I've built A10 and A13 motors that went to 10K. Those engines were in sports racers.

[G-Duax]

There is an exponential relationship between an engine's RPM limit and the cost. The same goes for engine wear and lifespan.

 

 

I hate to think of how much $$ I have in my Toyota long stroke inline 6 to make it live at 8500 :unsure:

Not to mention redesigning a lot of internal parts to get there.

 

But live it does, so much so that I am going to be bumping the rev limiter to 9500 this go around.

Wear & parts lifespan is considerably shortened, and the engine will not do 100k miles as if it were stock. 

But the pleasure it brings when I kick mustang asses with a 183 ci, non turbo engine is well worth the cost.

To add insult to injury, I've now put a 'camry' badge on the trunk :)

[Stoffregen Motorsports]

I want to see a vid of that Camry...er Cressida.

[G-Duax]

The only ones I have is from 8 years ago, and about 4 engines ago.

 

https://www.youtube.com/watch?v=iZj_CpuUKos

 

Here is what I'm working on now for induction.

[Stoffregen Motorsports]

Wow!

[Gery]

I recently put a 5 speed in my (previously automatic) ‘78 620 kc.  (Stock L20b, Weber, de-smogged at present). Shifting at 3k felt right but not aggressive. After reading all this though, I thought I must be being too conservative.  After pushing it, I’ve Found that power starts to drop at 4K and 5 k seems unattainable.  Thoughts?

[]2eDeYe]

Your rear axle is likely geared wrong for the 5-speed. 

[Gery]

Today I observed:

3rd gear @3,000rpm = 40mph

 

What differential gears should I be using?

[banzai510(hainz)]

Gery what you trying to achive here. Higher revs just for higher revs?

I lower gear car will rev higher. but wont get the top end. lower gas milage. 

a higher gear will maybe get soem better top end but will stop at a certain point cause motor will not have enought torq to turn it any faster.  Most 5th gears are just a overdrive to lower the motor 500 rpms or so while cruising.

I had a nice L20 and 1sr gear to 7K was ez. But in 5th now way. was a March box EI ignition

 

old cars the distribtors are old and wobbley ans getting to 6k might be made in a L16/18 but in a 20 I say no and run out of carb by then.

Edited April 16, 2019 by banzai510(hainz)

[john510]

4 hours ago, Gery said:

I recently put a 5 speed in my (previously automatic) ‘78 620 kc.  (Stock L20b, Weber, de-smogged at present). Shifting at 3k felt right but not aggressive. After reading all this though, I thought I must be being too conservative.  After pushing it, I’ve Found that power starts to drop at 4K and 5 k seems unattainable.  Thoughts?

It's an L-20b and not meant to make power at high RPM's.Mine has dual Mikuni's,a bigger cam and ported head.It's done making power at about 6,500 RPM's.Shifting at 5,500 works just as well.More than that i'm just killing it.

[Gery]

All interesting.  I wasn’t even thinking of the rpms until I came across the mention (above) of 5.5k shifting.  With my apparent shift range in the 3 to 4K range, I want to make sure I haven’t missed something....and that 3-4K shifts are not causing mechanical problems.   Frankly, after 4K my engine sounds ready to throw a rod or something.  Given its age, I’ve been fine with lower rev (3k) shifts.  

BTW, the truck hums along on the L.A. freeways and the empty stretches of the Pacific Coast Highway.

Soooo....should I leave well enough alone (if it is well enough and not a problem) or consider a differential change?  Or?

[datzenmike]

10 hours ago, Gery said:

I recently put a 5 speed in my (previously automatic) ‘78 620 kc.  (Stock L20b, Weber, de-smogged at present). Shifting at 3k felt right but not aggressive. After reading all this though, I thought I must be being too conservative.  After pushing it, I’ve Found that power starts to drop at 4K and 5 k seems unattainable.  Thoughts?

 

8 hours ago, ]2eDeYe said:

Your rear axle is likely geared wrong for the 5-speed. 

 

5 hours ago, Gery said:

Today I observed:

3rd gear @3,000rpm = 40mph

 

What differential gears should I be using?

 

The '78 automatic, 4 or 5 speeds used the same 4.375 differential gears. So not the gears.

 

Stock tire 620 at 3,000 should be going almost 37 MPH... I doubt you have the original tires on it and the speedo will be out because of this. Pretty close, or close enough.

 

 

 

5 hours ago, john510 said:

It's an L-20b and not meant to make power at high RPM's.Mine has dual Mikuni's,a bigger cam and ported head.It's done making power at about 6,500 RPM's.Shifting at 5,500 works just as well.More than that i'm just killing it.

 

THIS!!!

It can be made to make more power but it's intent is to be a derivable truck or car that has to start and restart easily, idle, be docile in traffic, have good mileage and have respectable low and mid range torque for pulling itself and a load around.

 

 

3 hours ago, Gery said:

All interesting.  I wasn’t even thinking of the rpms until I came across the mention (above) of 5.5k shifting.  With my apparent shift range in the 3 to 4K range, I want to make sure I haven’t missed something....and that 3-4K shifts are not causing mechanical problems.   Frankly, after 4K my engine sounds ready to throw a rod or something.  Given its age, I’ve been fine with lower rev (3k) shifts.  

BTW, the truck hums along on the L.A. freeways and the empty stretches of the Pacific Coast Highway.

Soooo....should I leave well enough alone (if it is well enough and not a problem) or consider a differential change?  Or?

 

3-4K power/torque range seems fine for a stock L20B. You won't hurt it... the danger (red) line is 7K. Put a brick on the gas and wait, it will get there. I had mine to 6 in first once, a total waste of time. My L20B drops off about the same. Shifting before 4 gives a nice kick in the ass in the next gear. But I swapped from a 3.70 to 4.11 differential. This will give you more 'snap' at the same speed but does not change the RPM shift points... they're just at lower speeds.

[Gery]

Mike- As usual, you are a wealth of great information.  I was hoping to hear your perspective.