ZCar Forum banner

Status
Not open for further replies.
1 - 9 of 9 Posts

·
Registered
Joined
·
37 Posts
Discussion Starter #1
i have a 76' with a 83 zx l28, the car has gobs of power all
the way to the redline, but my top speed is around 125, before i hit the redline..hoe far in the red can i go before something blows??
 

·
Registered
Joined
·
107,695 Posts
Re: how far into the redline can i go w/o blowing

> i have a 76' with a 83 zx l28, the car has
> gobs of power all
> the way to the redline, but my top speed is
> around 125, before i hit the redline..hoe
> far in the red can i go before something
> blows??

The answer to that question is that you can go all the way. The problem is not how far, but for how long. If the engine is mint, and in perfect balance, the only thing restricing you is the quality of you oil.

I am going to asume your racing the car at a drag strip. Whick means your going to be doing this in the summer when its warm. In this case, use either Moble 1 engine oil, with about a 20w50 rating,(this is a synthetic, the only synthetic on the market worth using, For at the moment it is the only one that will not dry your seals), or use an oil equivalent to an Aeroshell 100, this is a very high grade aircraft oil. The best on the market, but this is not a multi grade oil, so you will have to change it befor it gets near freezing. It will get to thick to start the engine, and if you do get it started you risk spinning a bearing. The 20w50 will do fine for the winter, but if it gets to about -30 celcius, it will become harder to start.

If you have any other questions, please write.

Will.
 

·
Registered
Joined
·
529 Posts
Re: how far into the redline can i go w/o blowing

> The answer to that question is that you can
> go all the way. The problem is not how far,
> but for how long. If the engine is mint, and
> in perfect balance, the only thing
> restricing you is the quality of you oil.

> I am going to asume your racing the car at a
> drag strip. Whick means your going to be
> doing this in the summer when its warm. In
> this case, use either Moble 1 engine oil,
> with about a 20w50 rating,(this is a
> synthetic, the only synthetic on the market
> worth using, For at the moment it is the
> only one that will not dry your seals), or
> use an oil equivalent to an Aeroshell 100,
> this is a very high grade aircraft oil. The
> best on the market, but this is not a multi
> grade oil, so you will have to change it
> befor it gets near freezing. It will get to
> thick to start the engine, and if you do get
> it started you risk spinning a bearing. The
> 20w50 will do fine for the winter, but if it
> gets to about -30 celcius, it will become
> harder to start.

> If you have any other questions, please
> write.

> Will.

Also keep in mind that the engine speed is also limited by the cam and valvetrain. If you are using the stock valvetrain and cam, I would not recomend taking the motor over 7000. At this point, the stock valve springs start to float and power drops off tremendously. If I were you, I would keep it below 6500. If you want more r's, look into getting a good cam setup. Motorsport Auto can recomend one suited to your engine and driving style.
 

·
Registered
Joined
·
107,695 Posts
Re: how far into the redline can i go w/o blowing

> Also keep in mind that the engine speed is
> also limited by the cam and valvetrain. If
> you are using the stock valvetrain and cam,
> I would not recomend taking the motor over
> 7000. At this point, the stock valve springs
> start to float and power drops off
> tremendously. If I were you, I would keep it
> below 6500. If you want more r's, look into
> getting a good cam setup. Motorsport Auto
> can recomend one suited to your engine and
> driving style.

This is true, but for some one who is only going to be reving through those RPM's quickly, and only from time to time, you should do OK with the stock stuff, if the springs are not worn out, witch is probally the case for most older cars. For even a 5-10 lbp drop on spring pressure is enough for a decreas in proformance in the higher rev's.
 

·
Registered
Joined
·
107,695 Posts
Re: how far into the redline can i go w/o blowing

Good luck getting a stock engine to survive anything past (or near) 8000 RPM. I asked a high performance engine builder how high they could get me on an L series engine. I was informed that if reliability was an issue, I could tap into the 7000-7500 range ONCE IN A WHILE. Something about crankshaft harmonics as the engine aproaches 8000 rpm. They also went on to inform me that I could go higher, they hinted at 9000 rpm but that main bearings and conrod bearings would need to be replaced frequently to keep things from going ballistic. They spouted a custom made crank with knife edges, exceptional balancing and improved lubrication. They also claimed the pisons and conrods had to be extremely light weigh versions. They also hinted that the top end would also need to be beefed up.

They failed to mention the Mobile 1 oil trick.... ;->

DR

> The answer to that question is that you can
> go all the way. The problem is not how far,
> but for how long. If the engine is mint, and
> in perfect balance, the only thing
> restricing you is the quality of you oil.

> I am going to asume your racing the car at a
> drag strip. Whick means your going to be
> doing this in the summer when its warm. In
> this case, use either Moble 1 engine oil,
> with about a 20w50 rating,(this is a
> synthetic, the only synthetic on the market
> worth using, For at the moment it is the
> only one that will not dry your seals), or
> use an oil equivalent to an Aeroshell 100,
> this is a very high grade aircraft oil. The
> best on the market, but this is not a multi
> grade oil, so you will have to change it
> befor it gets near freezing. It will get to
> thick to start the engine, and if you do get
> it started you risk spinning a bearing. The
> 20w50 will do fine for the winter, but if it
> gets to about -30 celcius, it will become
> harder to start.

> If you have any other questions, please
> write.

> Will.
 

·
Registered
Joined
·
107,695 Posts
Re: how far into the redline can i go w/o blowing

> i have a 76' with a 83 zx l28, the car has
> gobs of power all
> the way to the redline, but my top speed is
> around 125, before i hit the redline..hoe
> far in the red can i go before something
> blows??

It also depends really more than anything what cam are you using? To get any performance above 6500RPM you would need a duration that would make driving under 2500PRM pretty poor. If it's the stock cam then your power dropoff is very sharp and you are only hurting the engine.
Also, the datsun L6 is not a good high reving engine by any means, it would help a ton to have it expertly balanced but even then it's not recomended going above 8k for any prolonged period. The cranks suffer from torsional vibrations that really nothing can help so if you want the engine to last, don't go over redline, if you want to race it, get the right cam shaft and valve springs to handle it proper. If you go for the cam you will pretty much have to give up driving the car around town though unless you like rowing the car around town with the transmission gears. To give a idea on the duration to rpm ranges here is a example..
260 duration= 1500-5000rpm
270 duration= 2000-6000rpm, about the best for street driving
280 duration= 3000-6500/7000rpm better start getting a close ratio trans gears and tripple mikuni/webbers
300 duration=4000-8000rpm the above plus one balanced and higher compression ratio and will not work in street driving.
The lift plays some but it's the duration that really gives the car it's power range, if you see power charts you'll know when they hit the top they drop off super fast and it only strains the engine more than giving anymore power above the cam's range. I hope this gives you a better idea of what to look for in setting a engine for different operation profiles.
 

·
Registered
Joined
·
94 Posts
Re: how far into the redline can i go w/o blowing

what place are you doing a 125? The red line is there for a reason! It means that you should not drive above that line that is where the cars limit is! If you want to go faster and do it in a safe way then lay out the money! If you are going to take it there the way it is then it can stay there for a few seconds no more!!!!!!!!
 

·
Registered
Joined
·
107,695 Posts
Re: how far into the redline can i go w/o blowing

> what place are you doing a 125? The red line
> is there for a reason! It means that you
> should not drive above that line that is
> where the cars limit is! If you want to go
> faster and do it in a safe way then lay out
> the money! If you are going to take it there
> the way it is then it can stay there for a
> few seconds no more!!!!!!!!

I have to whole heartedly agree, even buy using a very high quality oil in a very well running stock engine, the best you are ever going to do is quick rev's into the red line, nothing sustained, and not all the time. I'd sugest that you only do this for that ocational street drag, and only 1 and 2 gears where you are reving up quicly with very little load on the engine. Other wise, take some time, do some research, and spend some money on good parts. If you are going to get into serious draging, first step would be to take the eninge and have it professionaly tuned and ballanced.

Will.
 

·
Registered
Joined
·
107,695 Posts
Re: how far into the redline can i go w/o blowing

> i have a 76' with a 83 zx l28, the car has
> gobs of power all
> the way to the redline, but my top speed is
> around 125, before i hit the redline..hoe
> far in the red can i go before something
> blows??

Some thing else you should do befor you do any engine work is swap the rear diff. with an automatic diff. The automatic will give you a higher top speed. about 30km higher. I know from experience, my friend did it in his 82 turbo. Vast increase in speed. But this of course will only work if you have a five speed manual.

Good luck. Will.
 
1 - 9 of 9 Posts
Status
Not open for further replies.
Top