Stock Flywheel vs. Fidanza Aluminum for Turbo L20B

[qwik510]

The Roadster weighs about 2,000 pounds, so that helps a lot.

And N/A so there is that too.

[datzenmike]

.... and put the top down.

[Pjackb]

The Roadster weighs about 2,000 pounds, so that helps a lot.

From what I understand a 510 weights 2050lbs to the roadster’s 1983lbs I doubt that 70lbs would make that big a difference ?

And N/A so there is that too.

With the turbo you would have more torque down low which would theoretically make it easier to launch I would think

[qwik510]

The Roadster weighs about 2,000 pounds, so that helps a lot.

From what I understand a 510 weights 2050lbs to the roadster’s 1983lbs I doubt that 70lbs would make that big a difference ?

And N/A so there is that too.

With the turbo you would have more torque down low which would theoretically make it easier to launch I would think

From what I recall, the 510 is about 200 pounds heavier then the Roadster 2000. So nearly 10% weight increase.

Yes, the turbo should make more torque down low, adding to an easier launch. But for what a I am looking for, a reliable driver with more power then my current stock L20B, I don’t want to find out that it doesn’t idle well or is harder to launch, etc. I also plan to add A/C at some point which will increase the load too.

[bertvorgon]

As a person who has driven a turbo 510 since 1974'ish, from stock to Holy Crap mode, you will find, like any car, the turbo is gravy.

As like any motor, the carb setup and tune is just like any motor. As you have a draw-through setup, as long as the run from carb to engine is not too long, response will be the same. Starting might be a bit of a task, as that is what I saw with some of the other draw-though systems.

So called bottom end will only be determined by the turbine housing size and how quickly it pressurizes the system. It takes "load" to help the motor build boost based on throttle opening.

As you have a 38/38, it will be interesting as to how that works in terms of jetting, through the range to wide open throttle. With my 32/36, the primary is jetted as almost a normal car, then, the secondary is jetted for more boost and wide open. Hope you have a wide band to see how it is doing.

Finding this interesting as not many over the years have done turbo on a 510 on the Realm.

Keep us posted!

[datzenmike]

The Roadster weight was in response to ease of take off not comparing to the 510. Lighter car can use a lighter flywheel. This is why trucks are 29 pounds even with the same L20B engine as the car. Larger displacement (more low torque) can use a relatively lighter flywheel. As I understand it the 510 varies between PL 510 UT 1,940- 1,962 for the 4 speed?, PL 510 UTA1,995- 2,065 for the automatic?, PL 510 UTK 2,017 for the 2 door?, PL 510 Wagons are the heaviest at 2,072- 2,138.

Really can't see the turbo making ANY difference at 1,500-2000 RPM clutch slip engagements. It's just not there.

[loungin112]

My dad gave me a different perspective on the topic of fly wheels. For context, he's an old drag racer (mid-70's).

He advised me to look at the powerband to determine whether to go with lightweight or stock; noting that fly wheels play a part in momentum of the engine.

A heavier fly wheel holds the momentum of the engine, RPMs dropping slower.
A lighter fly wheel releases momentum of the engine, dropping RPM's.

So, if your powerband is weighted towards the bottom of the RPM range (like my L20b), you should go with the lightweight fly wheel so the momentum returns the RPMs back down to where your power is found. Opposite for high revving engines that have their power at the top of the powerband...such as an SR20.

I skipped over reading some posts to get this thought out there...so maybe this was already posted. Either way, look forward to your thoughts.

[510rob]

That is EXACTLY what my flywheel came from at the time. It has been in service since 1978.

So you had a stock L20B truck flywheel lightened to 17lbs?

Here are some pictures of a L20B truck flywheel that Byron lightened for me years ago. It was by no means an aggressive MOI reduction, just an attempt to take some of the crazy-mass out of the stock weight.

http://www.the510realm.com/viewtopic.ph ... 3&start=15

[datzenmike]

Car L20B flywheels were scalloped on the engine side and on my crappy kitchen scales were 21 pounds. Trucks were about 29 pounds (if you measured 30 then 30 it is) for more stored kinetic energy to get a worst case scenario heavier truck and full load started on an incline. I also have a 240mm heavy and light (scalloped) flywheel. The heavy from a 720 or D21 Hardbody

[yenpit]

I think the 240mm flywheel was only in the 260/280Z 2+2...........NOT the 2seat coupes, thus NOT the 240Z. That said, you would need to buy a 2+2 240mm clutch AND have the correct throw out bearing sleeve!

[icehouse]

Adding a comment. A local 510 dude buddy of mine was over and we were on the topic of 71C's. Well he had a "bearing" noise in his trans that was driving him crazy. I loaned him a couple boxes. Noise didn't change. Turned out his super light aluminum flywheel allowed the drivetrain to pulse at highway speeds and make a "bearing" noise. He installed a stock flywheel and the noise went away. The plus is I learned one of my boxes wouldn't stay in 5th.... dang it. I wondered about that one.

[toylet]

You could buy a new chromoly 14lb RB26 flywheel from ebay for $133 and get a RB to L series spacer for $40. Use the 280zx 240mm clutch components on the RB flywheel.