L20B power needs

[Ben_upde]

I have a pretty healthy cam sourced for my L20B so I decided to do a build on it instead of an engine swap. Lookin for information and sources for making some decent (relative obviously) power out of it. 

What does it take to spin 9-10K rpms?

Will a very good balance job and valve springs get me there?

Lightweight, larger valves. Who/what/where?

The head will get a full refresh, seats and guides are not out of the question. What works?

Pistons and rods. Lightened and shot peened stockers ok for NA high rpm power?

Adjustable cam gear. Worth looking into?

 

I’ll likely utilize a standalone EFI system with coil on plug, port injection, knock sense and wideband feedback so fueling and ignition needs are not a concern at this point. 

 

There seems to be a little information sprinkled just about everywhere. Might be nice to consolidate everything into one thread?

 

Thanks in advance

[wayno]

L20b engines are not meant to rev that high, maybe if you were to use a Z20E crank, rods(6" long rods), and pistons you might get close, but circle track guys that rev 7000rpms are lucky to even get one season out of an engine, engines treated like that do not last long.

[Stoffregen Motorsports]

9-10K? Do you have $10,000?

 

To get them to rev past 8K the money required starts to multiply exponentially.

 

If you're into horsepower, consider a long rod 2200 or 2300. The 2200 uses a Z20 or Z22 block with 89mm bore, 6" N85 rods and a L20B or Z20 crank. The pistons are going to be custom forged or machined down KA24DE pistons. There are other "off the shelf" pistons that will work, but I have not used them. A 2200 built to run on the street, with dual 44's, can make upwards of 220HP.

 

The 2300 combo uses the same block and rods, but a Z22 crank and custom pistons. A 2300 built for the street, with dual 44's can make 240hp.  Adding custom rods to either of these packages isn't required for those HP numbers, but if you're going racing, they are a smart option.

 

Both of these engines starting cost is around $4000, but can run up to about $6500 or more depending on what parts you use. Dual carbs are fetching a lot of money these days, so EFI almost makes sense.

 

You don't need an adjustable cam gear. It just needs to be right, and then it gets locked down and never adjusted again.

 

So you haven't said if this is going to be in a street car or race car, or what HP you're trying to achieve. Or your budget, if you have one.

 

Rebello Racing, though known for their long wait times, are the hands down experts in L series engines. I would give them a call to see what's realistic inside your budget.

[datzenmike]

9-10K is rather an arbitrary number.  My 710's L20B and a brick might do that but still only make 90 hp. Wouldn't saying "I want to make over 250 HP" be better? The red line for a 86mm stock engine is 7000 RPM. Above this, rods and rod bolts begin to stretch towards failure from the acceleration g forces. I worked it out once and it was several tons compression and expansion 200 times a second.

 

Smaller engines can safely rev higher than longer stroke higher displacement engines but lack power.

Long stroke/larger displacement engines make more low speed torque than short stroke/lower displacement engines.

Of a modified L16 twisted to 8K to make 160 hp or a stock VG30 that makes 160 hp... I'll take the VG any day because it can do this forever reliably and will have stump pulling low and mid range torque. 

[tr8er]

High rev guys use L16's I believe.  Maybe even L18's.  L20B is more a great engine, but not at 10K.  

 

SM did you a real solid up there.  Send him a cookie.  

[Ben_upde]

Thanks for the info so far guys. 

I’m not too familiar with the L series so I am just trying to see what options are available for a build. 

With a similar rod angle as a SBC, I am just trying to gauge why higher revving engines aren’t necessarily possible. Having a smaller bore would also possibly equal a lighter piston but I may be completely off base. My co-worker is a circle track racer, running a stroked SBC at 8600 rpm for quite long stretches. The engine builder said he built it for 8900 rpm ??‍♂️

 

And as datzenmike said, the engine speed isn’t the goal/want/need. I know that with these smaller displacement engines, without going forced induction, increasing rpm range can be an effective way to make more power. 

 

I was thinking something along the lines of getting some custom, lightweight forged pistons made with much thinner (and newer tech) ring lands and rings. A set of good rods and ARP hardware, combined with a meticulous balance job should really stretch out the rev range of the L20B. 

Edited August 18, 2018 by Ben_upde

[datzenmike]

 If you have all the gas and air you need and no exhaust restriction, every doubling of RPM will double the HP.  In theory an L20B at 95 hp and 5,800 will make 190 hp at 11,600RPMs. Back in the real world.... port design, cam, valve size.... basically everything that allows a head to breath, never achieves this and why it's so expensive to try.  In the real world the engine has to live a long time, make good low and mid power to 3,000 to 4,000 RPMs, get good economy, make few emissions and be cheap to make.

 

 

This is Byron's 2.2 liter L head build. Has double side drafts and an unknown 'hot' cam. It makes just over 80 hp at 4K. Keep in mind this engine is 10% larger than an L20B so it would make maybe 80 hp at 4K on a good day. Now at 8K theoretically you would make 160 hp. A good KA24DE makes almost that in stock condition all day.

[Stoffregen Motorsports]

Most modern pistons, custom or OEM, use modern low tension rings, usually with a chrome top ring.

 

ARP fasteners don't make a good engine. And ARP rod bolts won't go to 10k in a Datsun motor unless they're the SPS/Carr style bolts in custom h beam rods. 

 

Small bores don't allow for big enough valves.

 

For the L motor, the power is mostly in the head, but street L motors love displacement. Take a race head off a GT4 L16 that makes 230 hp with 12.5:1 CR, and revving to 9500 or so rpms, now put that same head on a cast piston 2200 with 10:1, you're making about the same hp, but at much lower revs (@8000 peak rpm). 

 

You still haven't said if it's for street or for race. You also haven't mentioned the b-word (budget), so that's promising...

 

I've built dozens of these long rod street motors, and they sure are a blast to drive.

[paradime]

When it comes to torque, "there's no replacement for displacement", but the reason the little L16 stood up to the 2.0L BMW and Alfa Romeo was it kept delivering power for another 2000 RPMs. When you listen to John Mortin's #46 on the long straights running against the European cars with bigger motors, as they were grabbing another gear, the L just kept pulling.

 

I'm a fan of the short stroke high revving driving experience. It's more engaging and satisfying. Unfortunately, like Stofferson said, it's also more expensive to get an L16/18 to do that. Getting an L20b to do it is a whole other can of worms. Balance and springs ante going to get you there. L20s are putting out 200 HP with Webber side drafts, adapt EFI and a stand alone ECU, I'll bet you could beat that. Rebello racing is a great resource for parts and advice. http://www.rebelloracing.com/nissan1.htm

 

Best of luck

 

 

[DanielC]

Horsepower is just a product (multiplication) of torque and RPM, and a constant factor.  We all know that.

Increase the torque, or the RPM, you get more horsepower.  We all know that too.

 

Engines produce the maximum torque at one RPM, controlled by the camshaft, induction, exhaust, bore, stroke, connecting rod length, and other factors I am not thinking of.  The maximum torque is produced when the cylinder gets the maximum amount of air, and therefore can burn the most fuel.

 

Here is the dirty little secret that a lot of people do not realize, or think about.  When you shift the torque peak of an engine higher, you can take advantage of the increased RPM to make more horsepower, but in most cases, you make the RPM range that the engine is making the most torque narrower.  You lose lower RPM  torque to gain torque at a higher RPM.  You can compensate for this with by getting a transmission with more forward speeds, but in city traffic, you end up having to shift a lot more. 

With a higher torque peak, in search of more horsepower, you also lose fuel economy.

 

Another thing to think about is this.  If you set up an engine to run in extreme RPM ranges, you actually produce less torque, even at it's ideal RPM, because there is simply not enough time to fill the cylinders with air completely.  You lose volumetric efficiency. 

 

 

[Ben_upde]

All good points everyone. I do appreciate the insite and feedback. Hopefully i’m not coming across as a naysayer or a know-it-all. I express genuine interest as to what it takes to make power, and engine speed, and where happy mediums tend to fall. 

 

I am kinda leaning toward setting the 620 up for more autocross/drift style events where more engine speed can possibly be taken advantage of.

 

Of course 10k is an extreme, and a number simply thrown out there.

 

Is 8500 a more realistic number?

Bringing on power closer to the 5500 range will definitely make the engine doggy for in town driving, but with a properly set up close ratio transmission could make for a very quick, 2 stroke type of drive, which I am

fond of. 

I do understand that stock rods are not going to do the job. Aftermarket weight reduced forged is definitely gonna be a need. Smaller ringed and lighter pistons are also something I think will be of great help to the longevity of the engine. Increased compression ratio will be achieved with different pistons as well. 

[paradime]

Flat or even domed alloy pistons with coated skirts, ground valve pockets and Pro-Seal Rings would get you higher compression

Forged crank, racing bearings, H-Beam Rods with ARP2000 Bolts would hold it together

Serious porting and seats with BIG race valves 46mm Intake and 38mm Exhaust and a lumpy cam.

If you can find an adjustable sprocket, it would more than pay for itself in tuning options
 

Titanium valve spring with Moly Steel Retainers. 

 

The L has the intake and exhaust on the same side, so you'll need to design some heat shielding for the injectors.

Ceramic coating the header is a good start but you might consider wrapping it as well.

I've seen guys use U shaped aluminum with adhesive reflective heat shielding wrapping under each intake port and covering the injector on the sides.

 

If you're going to run this on an ECU I would use LS2 coil packs rather than on plug. Much stronger spark and faster recycle. 
 

[Stoffregen Motorsports]

I still disagree on the adjustable cam gear. I've seen enough of them come apart that I won't use them anymore. A far simpler option is to use a cam degree bushing. All you have to do is drill the hole in the stock L series cam gear and insert the bushing, degree the cam, and tighten the cam bolt.

 

 

 

Another aspect to the L series that you need to be aware of is the stability of the valvetrain. Historically it is very stout, but building one to run 8500 rpms or more requires a good head guy, and the right parts. Then there's the durability, which is limited. Running up to 8000 will mean a valvetrain inspection and valve adjust at least every time you hit the track. A broken valvespring is not uncommon when running that hard. You could probably go a year on this without problems.  A full race GT4 L16 valvetrain will need constant maintenance and a full rebuild at least once a year if no problems occur.

 

Lastly, what do we call you? Do you have pics of this truck?

 

Just for fun, here's a pic of broken L , KA and A series pistons from my collection.

 

[datzenmike]

 Much like adjustable coil overs that you set the ride height on once and never touch them again.

[Ben_upde]

6 hours ago, datzenmike said:

 Much like adjustable coil overs that you set the ride height on once and never touch them again.

? Not sure what this is referencing ?

 

[Ben_upde]

I have a Intro/build thread in the 620 section, you have probably seen it but here it is again because I enjoy looking at it ?

 

My name is Ben, so i guess that is what you’d call me. I’m a heavy equipment technician by trade, but not my sole background. I have spent quite a bit of time in the VW/Audi community with several builds on the 1.8t 4 cylinder line as well as the 2.7t V6 line. Complete ground up builds along with custom turbo manifolds, etc..

 

I am just exploring the many options of what I can do with the L20B until expense becomes higher than gain. At that time i’ll drop a longitudinal 1.8t in it and make 500hp cheaply and easily. The hum of the L20B properly set up though is my motivator at this point. Much like the Vr6 in my VW R32, the sound is distinct and enticing. 

[datzenmike]

11 minutes ago, Ben_upde said:

? Not sure what this is referencing ?

 

 

It's a car thing. Adjustable coil overs, very expensive, are used to set the ride height on strut suspensions. So the ride height is set, and then they never get used again. All that expense for shiny things that are just along for the ride.

[Ben_upde]

Are you referring to adjustable cam gear here? I know what coilovers are, and run a set of KW’s on my R32. They get adjusted at least twice a year, low for summer and 4x4 for winter.

 

Most of the expense in coilovers is for high quality damping components along with choices of spring rates to adjust between performance and comfort. There are super cheap sets that are, well cheap. 

[datzenmike]

Well you are the only one that does this.

[paradime]

23 hours ago, datzenmike said:

Well you are the only one that does this.

 

I disagree with Mikes rationalizations regarding coil overs, and his assumptions about everyone who has them. 

 

Saw this Ben and thought of you

 

 

Edited August 21, 2018 by paradime

[datzenmike]

Well there may be two of them that do. Far and away once the ride height is settled most who have them have no reason to adjust them again.

[Ben_upde]

14 hours ago, paradime said:

 

I disagree with Mikes rationalizations regarding coil overs, and his assumptions about everyone who has them. 

 

Saw this Ben and thought of you

 

 

 

He is right, there are a lot of ‘stancebois’ that set their coils as low as possible and leave it at that. 

On the other side of the token, there are plenty of people who use coilovers as intended, makin slight corner adjustments and tweaks to suit individual tracks/circuits and different drive styles. 

 

I saw that video. What really made me decide to locate another Datsun. Definitely potential with these guys. Sure, paying someone else to do the work for you can be expensive. Same as anything else really. 

[paradime]

I hear you guys there are plenty of posers out there, but I'd bet those stance guys are adjusting their ride hight more than track tuners. They adjust them to get to the show, slam them for looks once there, they change rims and tires like shoes and socks and every time they do it's another adjustment. Form or function, you can't do that without coil overs. Reasonable to say over 70% of them are set it and forget it types though.

[tr8er]

A couple of coil compressors, an alan  wrench, and 15 minutes and you've got your split collars adjusted.  

 

And if you really want high performance you can paint the strut tube red and the collar blue.  Maybe some gold Alan screws for 5hp.  

[datzenmike]

21 hours ago, paradime said:

 

 

 

 

 

Wish their 'dyno graph' read RPMs and torque, fuck KPH. So this L16 makes about 75%-80% more than a stock L16??????? If you say so. I would think a LOT less, making the EFI also less. What did the 10 hp increase cost?