Considering going from A to L series (again)

[Tom1200]

So I'm interested in some feedback from guys racing or tracking L series cars.

 

Here is the scope my A15 is belting out about 105whp 110 at best. While this is an huge improvement over the peaky A12 that dynoed at 80whp (top speed went from 98 to 111mph) and it also has some decent mid-range it still needs a close ratio box or more correctly a C/R box that won't break behind an A15

 

So in searching for something that will emulate the motorsports mid close ratio box I keep stumbling on 71 series boxes 280ZX or Roadster 5 speeds that fit the bill. Additionally for the $3000-$4000 a proper C/R box for the A-series would cost I think I could easily build a low stress larger displacement engine.

 

Well that lead to me thinking why not just stick in the L series engine. The vintage race class / group doesn't have issue with this a the Sunny Excellent AKA PB110 used L series engines, so eligibility isn't an issue. I can run up to 2.0 (L20 is a tight squeeze under the hood)

 

By comparison an all out A15 is 150whp vs 175whp for an L18. Additionally I have a friend racing a GTL 510 getting around 130whp from a restricted (per SCCA) L16. So the thought process is I could easily switch to an L16-18 etc and get 115-120whp that had decent mid range that didn't require revving the nuts off it. Note my A12 was revving to 8600 where as the torquey A15 makes decent power at 4500 and I only rev it to 8200. I try to limit the A15 to 7800 as it will last several seasons rather than wearing out the rings every 10 events.

 

The few negatives are the L series will add 50-70lbs to the car, I have good cylinder heads from the A15 and I'd need to fab a manifold to fit the FCR flatslide carbs I use now.

 

Positives are I already have an H190 in the car as well as ZX brakes and struts and L Series is a near bolt in for a 1200.

 

So how available are the V912 heads, what are service intervals to L16-18 revving to 7500-7800 on a regular basis etc? The L series build ups are well documented but not a whole lot of info on maintenance intervals and current parts prices.

 

Just looking for some thoughts from the group.

[Tom1200]

I almost forgot the car being competitive kind of doesn't matter (usually run 4-6th overall) as I'm usually the only one in my class and I'm likely going to switch over to me Formula 500 at some point (we just use the F500 as an autcross car at the moment). So the 1200 may be a track day only car (no open wheel cars at track days).

[Ranman72]

v912 is hard to find and pricey if you do 

the L20 is a great powerplant and for race purpose could be built to get close to 200 hp 

for street 155 to 160 is very reliable and a blast to drive 

[Stoffregen Motorsports]

A stock class (ITC) L16 makes about 120hp with 210 head, DGV Weber, good exhaust, etc. Balanced and blueprinted only. They rev to about 6500 before they run completely out of steam.

 

Add a good, mildly cammed cylinder head and bump the CR to about 12:1, run dual carbs (or your FCR's) and you'll see gains of about 20-30hp.

 

The cost of that engine is mostly in the head, as the bottom end could use stock rods and possibly a knife edged crank. Usual shot peening, metal lax-ing, nitriding, etc plus ARP rod bolts would help ensure a long life span...if you kept the revs down. Full groove main bearings and coatings on all bearings would be a good idea too.

 

What is the life span of this setup? Well, if you kept the revs down (under 8500), and ran 8-10 races a year, you'd need to rebuild the head about once a year. You may have some failures along the way, which will open the can of worms for better parts (titanium valves, Carrillo rods, etc), but if you did regular maintenance (including the occasional broken valve spring at the track) and exercised restraint on your cam choice, once a year would do it.

 

You don't need a V912 head though. Any closed chamber A87 head can be made to work with that piston combo. V912's were a late replacement head that was only partially ported, but otherwise identical to A87/219 heads. Actually, the ports were rather small, leaving the port work to the experienced builder.

 

You'd be lucky to find one too. Guys like Rebello and Ermish find and hoard them for their good GT engines.

[bajango]

The 219 heads pop up every so often. I bought one after a month or two of lurking a couple of Datsun parts groups on facebook and the classifieds here. In fact I may be selling mine

soon. I've been getting serious about selling my 521 and L parts and buying a roadster. Still on the fence. My point is, they're out there to be had still.

[Tom1200]

A series engines are good for 9K with stock parts, the only thing I've done to mine is had the bottom end balanced. The cam is fairly moderate with a .420 lift and 278 duration (Nissan A series race cams were 480 with 300 duration). I use a GX head with 37/30 SI valves with the ports cleaned up and 3 angle valve job. Most of the porting was concentrated around the valve seat as on the A-series they protrude into the port by about 1mm so it's basically a 2mm restriction.

 

The A15 as 25 events on it, around 45-50 hours and it still runs strong. Note I do 5 events a year

 

So if I understand correctly a moderately tuned L16 L18 or L20 would be between 100-135HP at the wheels. Also keeping the motor to 7500 would go at least 10 events possible more?

[Stoffregen Motorsports]

That's about right, but let's be clear, an L16 should not be compared to an L20B. The stroke, short rod length and bore of the L20B certainly make more power, but the revability is not as great as the L16.

 

If you like the revs, go L16. If you want more HP while spinning lower RPM's, the L20B would be the obvious choice.

 

The power potential (in full race trim) for both of these engines is much greater than mentioned above, but the cost spirals exponentially upward as you make more power.

[Tom1200]

Totally understood on the differences; the L16 is out of a sportin see-Dan and the L20 is out of pick-em-up thruck.

 

As for the power I've seen L18s between 170-180whp & L20s between 190-207whp but as you mention the get closer and closer to holy hand grenades of Antioch.

 

Definitely looking for 6 hour service intervals. I try to keep the motors to around 75% of full race; a perfect example is my A12, at 73whp it went for about 8 seasons but once bumped up to 80whp it wore the rings rather rapidly. As with most Datsun engines more power means more revs.

 

As I'm not looking for a huge bump the L18 seems the right pick of the 3 as the L16 is only 80cc more than my A15 and the L20 relative to the A15 & 60 series gearbox (183lb engine 54lb gearbox) is kind of porky. I also seem to recall the L18 can also be bored out to 1850ish with L28.

[Stoffregen Motorsports]

You can make a 1900 out of an L18 with 87mm pistons and using L16 rods the rod/stroke ratio improves.

 

Finding a good L18 may be the hard part.

[docbainey]

What Stoff said.

 

You could probably amass a small stable of L20s for cheap before you could find an L18, at least in this part of the country. Depending on your build level, if you are going to use forged pistons, just have them made to utilize longer rods, Z22 rods I believe?

 

This still leaves you with a gearbox problem though?

[Stoffregen Motorsports]

Z20 rods are the longest, at 6". In an L20B, they make a very smooth running engine.

[Lockleaf]

I have an L18 i might be willing to let go of. Should it come to that feel free to pm me. Though i imagine shipping an L18 from Utah won't be cheap.

[Tom1200]

Lockleaf I'm not sure where In Utah you are but I'm in Las Vegas. One of our local guys has an L18 in his 510 but he's working on a L20 to replace it.

 

@Docbainey as for the gearbox issue; the 280ZX so called mid close box could be bolted in. It has the same ratios as my mid-close 4 speed comp box. If I'm to fit an L series the goal would be something with a bit more power but more importantly a broader powerband.

 

Now should the Formula 500 become the primary vintage race car, the 1200 would be a track day only and I'd go with one of the big bore L/Z motors. Using the L instead of a more motor would still keep it vintage eligible as a backup car.

 

Tom

[Lockleaf]

Oh nice. I thought you were on the east side of the country for some reason. I'm about 6 hours from Vegas, but South of salt lake city.

[RoadRace]

FYI, a friend of mine has a race-only A-series in his car. After doing the same research you are, he said "screw this" and dropped in a stock used 4AGE 1600cc toyota twin cam. Never been happier. Car is easier to drive, easier to race and is faster. win-win...win. "Race motors are for the birds" he proclaimed happily. I got the old crank trigger and MSD stuff off the A series...somewhere. point is he was a happy camper knowing all he had to do was change the oil and drive the car.