Engine build ideas, need some help (looooong story)

[datzenmike]

15w40 makes me wet...

 

 

Run 10W30 in the winter.

[KoHeartsGPA]

Delo 400 and Rotella T have the additives our L series NEED, and they're very inexpensive.

 

Anyone know about Delvac? We use them on diesel engines over the other brands, but i havent researched it, i do know our trucks have a noticeable performance difference between the three oils, Delvac comes out cleaner and way less blowby from the crank vent tube, plus we can feel the engine run smoother and the viscosity of the oil is much better than the other two.

[Stoffregen Motorsports]

Could I benefit from a spray bar and if so, how can I get one?

240z's came stock with a spray bar, so obviously Nissan thought it was a good idea at some point. But for a mild street motor, you don't need one.

 

There are two ways to get a spray bar. One is to buy a spray bar kit, another way is to buy a L24 cylinder head and use the cam towers off of it and shorten the stock spray bar.

[bajango]

So e31and e88 heads both? I think there's a couple L24 heads being sold in my area. I might try it, just cuz

[banzai510(hainz)]

send a link to the L18 pistons for sale!!!!!!!!!!

 

 

I would just buy a higher volums oil pump than run a spray bar.

[bajango]

Sorry banzai, it's through a warehouse that only sells to dealers. If you're located in the northwest,. Call Baxter auto parts so they can call EPWI. Otherwise I could do it for you... somehow since I'm across the country currently

[bajango]

It won't be as cheap for you as it is for me though.

[banzai510(hainz)]

I dont need a set but soemtimes people look for them

[bajango]

Oh alright. Well Peeps can hit me up when I'm back home around February. I can't get a few new L parts here and there.

[KoHeartsGPA]

I highly doubt they really are L18 pistons, ive seen listings for them and evey time i call for information it turns out they actually are the L20b pistons listed for the L18....

[scooter]

If your going for max power you want the long rods, but since it's a " stock rod" motor and your not gonna turn it more than 7500 anyway so use what's available. I'm with Mike, l20b rods and ka24 pistons and make a 2.3. Even with zx valves and a big cam it ain't gonna past that unless your a porting God.

 

I'm running the isky z-196 and it's okay around town, but in my 2.3 it comes "on the cam" close to 4000 and seems to start running out of huff at 7500.. I need a better intake and exhaust and carbs to make it go further. But it's also on nitrous and that torque curve doesn't dive before the Rev limiter. I need some 50's and an intake.

 

My motor has stock l20b rods shot peened with arp bolts. The pistons are cp custom forged with tool steel wrist pins, I figure it's fairly safe to run this combo at 7500 cause the piston is quite a bit lighter than the stock one, and the wrist pin is probably half the weight of stock.

 

When you have big valves in there with a big cam mind the piston to valve clearance.

[Tom1200]

When ever these build threads come up the one thing that always gets overlooked is the gearbox; the stock Datsun boxes drop 3000 rpms between 2nd and 3rd, even the ZX mid close street boxes drop around 2400-2600 rpms between 2nd and 3rd. Building a revvy motor sounds cool but the reality can get tiresome in a road car. I'd be wanting a 6 speed in a street car if I went this route.

 

The other dilemma is the rorty cam that supports a revvy motor makes rolling away from a stop a pain as well. I have a fairly moderate build on my A15, the cam is only 280 degrees of duration and to get it moving out of the hot pit means revving it to at least 4500rpms. This is with a 4.38 rear gear and short 20.6 tires.

 

On the bike carbs; my 1508cc motor is sporting 39mm flat sides so 41s on a 2.0 liter probably isn't overkill.

 

Finally all I'll add is torque torque torque torque and torque, oh and did I mention torque.

 

Tom

[datzenmike]

We're talking the 521 4 speed same one as the 510 wagon?

 

Well, lets put this in perspective. RPM drop between gears should be expressed as a % unless you supply the starting RPM point. Second gear is 2.117 and third is 1.416 or a  33% drop in RPMs. It doesn't drop 3,000 between 2 and 3 unless you are revved to 9,100 RPM in second and shift to third. This would drop you down to 6,100 in third.

 

On a 6,000 RPM shift you would drop only 1,980 RPMs to 4,820 but this is still 33%

 

 

 

The 71B mid ratio box is 2.077/1.308 or 37% drop. Using the same engine a 9,100 RPM shift from 2 to 3 would drop the RPMs 3,367 or down to 5,733. A 6K shift drops 2,200 to 3,780. (still 37 %)

 

The 71B close ratio zx box is 1.858/1.308 or a 30% drop. Again a 9,100 RPM shift into 3rd will drop 2,730 RPMs off down to 6,370 RPMs. A 6k shift drops 1,800 down to 4,200 (still 30 %)

 

Nismo Option 3 box is 1.601/1.296 for an 8% drop. Once again a 9,100 RPM shift from second to third would drop only 728 RPMs off or down to 8,372 RPMs in third. A 6k shift drops it 480 down to 5,520 (still 8 %)

 

 

9,100 RPMs is a bit high for the average street car so I worked out 6K shift points also.

[bajango]

I'm putting in a 5 speed from a 720. But if I remember right, 1-4 is the same and then 5th is just the..."overdrive" for the lack of a better term

[Lockleaf]

There isn't a better term. That's the actual term.

[datzenmike]

1,2 and 3 are gear reduction. More engine turns that output turns. This multiplies torque to get a heavy vehicle moving.

 

All 'fourth' gears even in a 5 speed have a one to one straight through drive with one turn input for one turn output.

 

Fifth gear is an over drive, where one turn input gives 1.12 to 1.25 output turns or 12-25% more

 

 

 

I'm putting in a 5 speed from a 720. But if I remember right, 1-4 is the same and then 5th is just the..."overdrive" for the lack of a better term

 

 

yes and no. 1,2 and 3 in the five sped may have slightly different ratios that your 521 4 speed. Fourth 'gear' in the 5 speed will be exactly the same as your 4 speed in forth. Fifth gear will lower engine RPMs for cruise speeds on the highway.

 

Only the 1980 5 speed will fit your L16 engine.

[bajango]

I bought a 1980 720 for the L20b and the 5 speed. That's why I'm building an L20b and throwing in the 5. I read up on the 5spd swap so I know I need to shorten the trans bracket/ driveline etc. I want to make my 521 a little more fun. That's why I'm doing all of this. Plus I'm tired of turning 4K rpm on the highway....

[datzenmike]

Make sure you use your 4 speed throw out bearing collar and DON"T mix it up with the one on the 5 speed!!!!!!!!!

[bajango]

If I'm using 720 drivetrain parts, shouldn't I stick with 720 parts all around?

[datzenmike]

Course not.

 

All clutches are matched to their through out collars. Think of it this way.... your 521 clutch and pressure plate also includes the throw out collar... keep them together as a set.

 

 

 

 

Make sure you replace the throw out bearing though. It has wear on it and you have no idea what shape it's it. Now it is was located in the glove box it wouldn't matter if it starts squealing in a month's time, but it isn't. It means taking the transmission out all over again to replace it. Do it now.

[bajango]

Oh. I was gonna use the 720 clutch parts. Clutch pack, bearing, slave etc

[flatcat19]

Plus I'm tired of turning 4K rpm on the highway....

4K? Is that all you got? Meh. It's an L16. Wrap that fucker out to 6.

 

Loud as hell, but boy is it fun to pass people on the freeway.

 

The looks on some people's faces. Lol.

[datzenmike]

Oh. I was gonna use the 720 clutch parts. Clutch pack, bearing, slave etc

 

Your 521 has an L16 and the flywheel is mounted with only 5 bolts. The 720 L20B flywheel is 6 bolt. In addition the 521 PP is only 200mm diameter, the 720 PP and clutch is 225mm so won't fit. No problem keep it as it is.

 

Keep your release collar (the thing that holds the release bearing) and put it on the 720 transmission clutch arm. Be sure to replace the bearing.with a new one.

 

 

Yes use the 720 slave and pushrod. It's self adjusting unlike your 521 slave.

[bajango]

4K? Is that all you got? Meh. It's an L16. Wrap that fucker out to 6.

 

Loud as hell, but boy is it fun to pass people on the freeway.

 

The looks on some people's faces. Lol.

I put that bitch past 6k every so often. I have an open chamber magnaflow that's kind of small so it's a little loud... I personally think it's too loud, but whatever. I never really liked the neighbors anyway.

 

And mike, why not just use EVERYTHING 720? I'm still confused.

[banzai510(hainz)]

make this simple

Pull 720 motor and trans/slave/release collar/bearing  together install in 521

 

Im not sure on the slave as the 521 hose goes staright in the slave unlike say a 510/200sx ect which HOSE comes from the side.

 

 

521 should be quiet anyways I run a Dynomax Superturbo but wish a I got a quiet Walker Turbo.  521s are just to whinney