L16 piston / build options

[datsunrides]

On my recently acquired 521, I have discovered the #4 piston is shot. I'm going to rebuilt the bottom end and replace the pistons. It's been quite a while since I've played with a L series, but I think these are my 2 best options,

 

Go with standard L18 pistons. IIRC, the L16 can be bored 2mm for these.

Go with L24 flat tops, at least .5mm over

 

What will be the deciding factor is compression ratio. I'd ideally like to be in the 9:1 range. Can anyone tell me what the end compression would be with the 2 piston choices. I will be using a U67 head, since I have one that looks to be freshly rebuilt.

 

Thanks, Mark

[datzenmike]

U-67 Head

L24 flattop 0.5mm oversize....................... 8.7

L18 stock pistons...................................... 8.49

 

Closed Chamber Head

L24 flattop 0.5mm oversize....................... 9.30

L18 stock pistons...................................... 9.10

[hooliganPL620]

if your running a truck motor get truck pistons every piston manufacturer i talked to said the valve clearences in the pistons are there for a reason i picked up a itm set up for 250 with all new bearings gaskets etc etc and the order sheet rates them at 9.5:1 compression which ill probably be a little below that bc im running a a87 head

[hooliganPL620]

http://www.itmengine.com/catalog.html

[datzenmike]

if your running a truck motor get truck pistons every piston manufacturer i talked to said the valve clearences in the pistons are there for a reason i picked up a itm set up for 250 with all new bearings gaskets etc etc and the order sheet rates them at 9.5:1 compression which ill probably be a little below that bc im running a a87 head

 

None of the L series motors have valve reliefs in them. They do have various dish in them but all can run flattop without any problems at all. These are my collection. I don't have a flattop L16/18 but I do have, from left to right.

 

Z24 with 15cc dish, Z22 with 9,32cc dish, Z20E flattop with reliefs, L20B with 11.36cc dish.

 

 

The L18 and L16 would look somewhat like the L20B but with much less dish. 521 truck and 510 car pistons were the same part number.

 

 

 

.

[hooliganPL620]

huh mine are a bit different mike ill post a pic when i drop em in there dishes with valve recesses in them itm says they do that for clearence issues? and the factory pistons i pulled were very similar also had recesses for the valves what is ur gander mike cus you deffinitly know more than me

[datzenmike]

Yes, most definitely post 'em up. Measure the diameter too.

[datsunaholic]

As Mike said, L-series engines do not have nor need valve reliefs. The only cases I can think of that would possibly need them are if you ran massive, sodium-filled valves and were turning sustained 9500 RPM. Or milled the head down way past the safety margin. NAPS-Z pistons had the reliefs because the valve angle was much greater, causing intrusion into the bore.

 

Datsun L-series motors are not built any differently for car or truck applications. These aren't Chevy 350s. In fact the only difference between a Car and Truck l-series longblock for any given year is the oil pan/pickup and dipstick location. L16s did have different smog equipment, but internally were identical. Even the cams are the same.

 

I have a (NIB) set of dometop L16 racing pistons (not forged though), supposedly good for 9.5:1 compression on an otherwise stock engine. Also a set of flattops. They are STD bore though. I wouldn't use them with a peanut head due to possibly contacting the head surface. If someone actually wanted these I'd sell them for $150 a set.

[datsunrides]

U-67 Head

L24 flattop 0.5mm oversize....................... 8.7

L18 stock pistons...................................... 8.49

 

Closed Chamber Head

L24 flattop 0.5mm oversize....................... 9.30

L18 stock pistons...................................... 9.10

 

Thanks Mike. This helps a lot. If you want, I'll send you one of the L16 flat tops gratis when I break down the engine for all the great advise you dole out.

 

Next question, would you guys think the extra compression an A87 would give is worth the small trade off in flow? (stock for stock) It would seem to be kinda a wash. The truck will see a lot of freeway driving so midrange torque, throttle response, and fuel mileage are key. Along those lines, is the L20B cam the right choice for these parameters, or is a slightly larger cam beneficial as it will be mostly working in the 3k-4k range. The wrench in this is the auto trans. Don't want to lose too much bottom end torque and make it sluggish (well even MORE sluggish) off the bottom. Cost is of course a concern also. Trying to do this as cheap as possible without being "cheap", comprende' ;)

 

Mark

[datzenmike]

I think an A-87 closed chamber is perfect for the smaller L16. The smaller diameter runners will give better throttle response. I think the A-87 has the same cam as the L20B, not sure.

 

Sure I'll take a piston. :lol:

[datsunrides]

Well, may not end up building the L16 after all. Turns out it needs more than I want to spend on a L16. I was hoping to fix it on the cheap, but if I need to spend almost as much as it would cost to get a used KA-E, guess where I'm headed? :lol: Datzenmike, PM me your address and I'll see about getting you a piston.

 

Mark

[hooliganPL620]

hey mike you have facebook im tired of trying to figure out how to post pictures

[datzenmike]

hey mike you have facebook im tired of trying to figure out how to post pictures

 

Here's all you need..http://community.ratsun.net/topic/691-how-to-post-pictures-and-keep-online-photo-albums/

 

I don't fb

[banzai510(hainz)]

Silvolite makes pistons.

Ebay?

I seen pistons for cheap. under 100$ for a new set.Its machine shop that costs money.

By then go with a L20.

 

KAs are more work than you think. Electrically! fitting. L motors are EZ .

a L20 with a 38/38 weber will be a noticable improvent.

 

get a A87 or a W53 head when using the flattops to get close to 9.9.5 compression.

 

U67s will desiel /ping on cheap gas.

[datsunrides]

No need to worry Hainz, I have a few EFI swaps under my belt. They really are simple until you get to OBD II swaps.

 

4G64 in a 75' Colt. Been running great for 2 years

 

 

6G72 in a 72' Corolla wagon. Not complete now, but is wired up and running.

 

 

Turbo EFI U20 in a 66' roadster. I built all the plumbing myself and runs a standalone. Been running for about 3 years.

 

 

It's in good hands. ;)

 

Mark

[banzai510(hainz)]

if you done those 3 swaps I would even worry about doing a L16

a beat KA will kill a L16

[pl521sss]

Hey Mark!!

So you finally got a 521

Just stuff it with that U20T

You'll be good to go :lol:

 

 

 

 

On my recently acquired 521, I have discovered the #4 piston is shot. I'm going to rebuilt the bottom end and replace the pistons. It's been quite a while since I've played with a L series, but I think these are my 2 best options,

 

Go with standard L18 pistons. IIRC, the L16 can be bored 2mm for these.

Go with L24 flat tops, at least .5mm over

 

What will be the deciding factor is compression ratio. I'd ideally like to be in the 9:1 range. Can anyone tell me what the end compression would be with the 2 piston choices. I will be using a U67 head, since I have one that looks to be freshly rebuilt.

 

Thanks, Mark

[datsunrides]

if you done those 3 swaps I would even worry about doing a L16

a beat KA will kill a L16

 

Hainz, I was hoping to fix the L on the cheap. As you know, they are fine motors. Once the repair price went up, it just makes more sense to go to something newer and I really like FI over carbs.

 

 

Hey Mark!!

So you finally got a 521

Just stuff it with that U20T

You'll be good to go :lol:

 

How you doing Abe. Once was enough with the U20. :lol: I can probably build 10 stock

 

KA's for what I invested in the U20! Kinda cool to have something nobody else has. :D

 

Mark

[hooliganPL620]

anybody got a set of headbolts? cleaned mine up today and they looked a little sketch (a few pitted and wavy on the threads) and no one makes the head bolts wtf so arp offered to make me some but id ratherjust have a good factory set....called nissan those guys are fucking stupid around here

[datzenmike]

L16 head bolts... Tell them to look up and confirm...

 

LONG........ 11059 21000 new number 11059 P3000 qty. 4 at about $5 each for both sizes.

SHORT..... 11056 21000 new number 11056 P3000 qty. 6

[banzai510(hainz)]

hooligan,

this is me If I was going to order head bolts I would get the 280zx turbo bolts.Courtesy Nissan out of texas has these on the site. or the ZStore list them also.or nissanparts.cc if you have a part #

Since you have a L16 I would just use the old headbolts as the L16s only need about 40pounds torq. Most cases they are OK. I reuse mine all the time.

[hooliganPL620]

i will take a picture of the threads for you the head bolts are not usable on 4 of them....habbit tells me

[hang_510]

anybody got a set of headbolts?

 

so arp offered to make me some but id ratherjust have a good factory set....

 

called nissan those guys are fucking stupid around here

i have a few USED sets avail

 

 

ARP studs sets are ~$100

 

 

try chico nissan

[hooliganPL620]

thank hang i ordered them from nissan this morning have to buy the longs in packs of 10 and the shorts come individually so with my account think im paying 62 bucks for a set plus 6