Questions on L28 dyno numbers

[Guest InterSpool]

Hi, I'm new here and used the search button many times so please bare with me! I'll have to say I've fallen in love with the Zs... so let me begin my questions:

 

1) Using EFI, has anyone obtained 100bhp/liter on the L28 engine using any particular setups? It seems that CR is the biggest thing holding these engines back. I tried hard to find some stock L28 dyno charts, so if anyone has those please post them for me.

2) Again, assuming EFI ... what do you think the output of this setup would be (I used the engine calculator)?

 

L28 block, L28 rods, N42 head, LD28 crank, L28 flat top pistons, and a .25-.50mm fly cut. Depending on the fly cut, it yields 12.13-12.5 CR. What do you guys think of this setup? How much are the LD28 cranks?

 

Thanks in advance guys.

[Guest bastaad525]

you want 100bhp per liter from an L28? gonna take a LOT to get there. Well, for a stock block 2.8 litre, that's 280hp at the crank... dunno if that's been done before, but if it has been that'd be about the limit, and you'd probably end up with a motor that wasn't very fun on the street... the power band will all be at the top. You'll need a hogged out head and a really wild cam, and either something like tripples or better yet, programmable EFI. I do know that Rebello builds stroker motors like a 3.0 or a 3.1 that they claim will have over 300hp at the crank, but they cost in the range of $5000 and up, and personally, unless you do most of the work yourself, like machine work and dissasembly and assembly, I dont think you could do it for much less than that. It's been said a thousand times, and I'll say it again, if you're gonna spend that kind of money, you're better off going V8 or Turbo, as you'll get more bang for your buck that way. A stock 2.8L motor had from 135 to 145hp at the crank, according to nissan. You will hear some people claim that they made 170hp in the early 280z, that is WRONG as this was GROSS hp, whereas in the ZX's they went over to NET hp, which is how all cars are rated now. So, figure 140hp average at the crank, probably around 115hp to the rear wheels (measured on a chassis dyno). There are many four bangers under 2 litre's today putting out more than that. The problem with the L28 is the head... they are really antique in design and just dont flow nearly as good as todays twin cam, variable valve timing heads. Of course, add a turbo on there to force the air in and that all changes. 300 crank hp on a 100% stock block and head L28 turbo is not hard at all. The compression doesn't make that big of a difference on these motors, and it's not what's holding them back. Lots of guys run street L28's that are pushing 10:1 compression or higher and still end up with less than 200rwhp (maybe 230-240 crank hp). Much higher than that and detonation can become a serious issue on pump gas. I dont think you could safely run pump gas 12.x:1 compression. Really, the only thing holding them back is the head design, open up the head, run a good cam, and good free flowing induction able to supply all the air and fuel the head will flow, and you're on your way to making good power. Maybe not 100bhp per liter, but you can get pretty close.

[Guest InterSpool]

Thanks for the response. Yes, from what I have read so far is that the head on these motors is the biggest restriction - technology has come a long way . 100bhp/litre is the 'magical' number for NA engines. I was definitely expecting to use EFI to get there, and actually I wasn't expecting it to be possible at all. And yes, I don't know about the reliability of pump gas with 12+ CR, but adjustments can be made to run about 10.5-11 which I don't think should be a problem. There don't seem to be many dyno charts out there for people running L28 NA, I guess they aren't too popular? I would be more than happy with 200rwhp on an NA L28 (given that not too much $$ was involved).

 

From what I notice even on the turbo'd L28s the dyno charts get really shaky in the 4.5k+ RPM region. I'm assuming this is because of no vario-cam and whatnot. Can someone shoot me a rough estimate on how much an L28 turbo setup costs? Stock turbos, EFI, stock engine? Thanks.

[Guest Nic-Rebel450CA]

Being that the engine is more of the "old-tech" you are more likely to hit the "old-tech" magic number which is 1HP/cubic inch. The 280 engine is about 170ci. Hitting 200HP at the crank might just be possible without radical engine work and $$, but 200HP at the wheels is going to be very unlikely.

 

What kind of Z are you putting this in? My 240Z with an L28 with dual SU's and 3.96 rear end gears was pretty quick, and I estimate it made about 140HP at the crank, maybe a tad more. Because of the lighter weight and better gearing, it could probably take a heavier Z with more HP pretty easily. Focusing specifically on HP may be unlikely to get you the results you want. The better question may be to ask what you would like to end up with and determine what factors/mods including HP would get you there.

[Dan Baldwin]

With a good cam and headwork, you could conceivably get to 100 crank hp/liter even at at pump fuel friendly CR levels. I'm almost there (255 rwhp, 3.1 liters, maybe 95 crank hp/liter?) myself. 12sec Norm is close as well, at 107.x mph in the 1/4. John Coffey is most definitely there, at 13.5:1 cr using race fuel. My engine is a 3x2 carbureted 3.1 liter, shaved/notched KA24 pistons, LD28 crank; Norm's is a modified SU carb 2.9 liter, shaved L28 pistons, LD28 crank; John's is a fuel injected 3.0 liter, forged pistons, L28 crank.

 

Your proposed setup won't work, as even with .5mm shaved off, the pistons will be ~1.5mm above the deck. Even with a 2mm gasket, that leaves only ~.020" piston/head clearance. I'm not sure how much Norm had to shave off his L28 pistons, on the order of 1.5-2.0mm I think.

 

You can get there with or without the LD28 crank. 5% is 5%, though, IMO you may as well get it. You then can overbore from 3mm to 4mm over and use KA pistons, if you're not going too wild on CR. I would guess that at somewhere around 12-12.5:1 you'd want to go forged.

 

I believe LD28 cranks are going for ~$250 these days.

 

I bet you can build an engine like mine for ~$6000. John's into 5 figures I'm pretty sure. Norm probably only spent 50 cents on his engine

 

As far as "old-tech", dohc multivalve isn't much newer tech than SOHC 2 valve. Also, if you're unlimited as to what mods you can make, turbo or v8 will beat the absolute crap out of NA L6 in terms of power/engine weight (which is really more important for performance than power/displacement).

 

But going either of those routes you won't get nearly the stunned respect of the big-inch or turboed machinery you beat the crap out of at the track with an NA L6!

[Guest bastaad525]

I had dynoed my N/A L28. First, when it was in my '80 ZX. It was a stock block L28, overbored .060 over, making it a 2.9L. I was running flat top pistons, and an N42 head which was stock (not ported), except for running stainless steel, tuliped and polished valves. Cam was stock. Also was running stock EFI. Compression was about 10.3:1. I also had a K&N filter, big bore throttle body with the intake manifold match ported, 3-2-1 header into 2.5" exhaust, thru a free flow cat and muffler. I can tell you the stock EFI was NOT happy with the high compression and I had a lot of detonation. I ended up just throwing an adjustable fuel pressure regulator on there and upping the fuel pressure a bit to fix it. I dynoed on a dynojet and made 145rwhp and 161 ft lbs of torque, about 160-170 crank hp. I also had a lightened flywheel, ACT six puck clutch, and a 3.9 diff. I ran an elevation corrected 15.3 in the 1/4 mile (was actually a 15.8, at like 2500 feet if I remember right). Estimated weight of the car was about 2800lbs.

 

I then moved that entire drivetrain over to my current 240. I swapped out the EFI for SU carbs, and installed a 480 lift 270 duration cam (mild street cam. Everything else was the same, oh except of course I lost the cat. I dynoed again and made a much nicer 170rwhp and 170ft lbs of torque, which is pretty close to 200hp at the crank. I never got to race that setup but I have weighed the car, at 2320lbs and given the HP I should have been good for a mid-to-high 14 in the quarter. I'd have scanned the dyno sheets to show you but I gave them to the guy I sold the motor too.

 

Keep in mind that was with a STOCK head. Good headwork is really where a lot of power is freed up on these motors. Had I spent the cash to port and polish the head I could have probably gotten close to 200hp at the wheels. Had I done the head work and run triple carbs and a hotter cam, I could have probably seen even higher than 200rwhp. Powerband would probably have been between 4000-7000rpm, so street driving would have started to suck.

 

Stock L28's usually achieve peak hp at around 5000-5500 rpm. The cam will be the big deciding factor in this. When I installed the mild cam My hp peak moved from 5000rpm to about 5600rpm. Hotter cams will move that up more, but low rpm street driving will really begin to suffer. Also the intake can make a lot of difference. Guys running hot cams and tripple carbs see good power up to 6000-7000rpm.

 

The problem is the money investment. You're gonna spend a lot to get even the numbers I was getting from the last iteration of that N/A motor. And really it was almost 'done', not much room to grow, and those last couple things I coulda done (triples and headwork) would have been another couple grand for that extra what, 30-40hp? With the turbo motor my initial investment was considerably cheaper (though I've had lots of expensive bad luck since then), and right off the bat I was making that 200hp at the wheels easily, on a 95% stock setup, pretty much just turned up the boost. AND there is PLENTY of room to grow. The same ~$2000 that would have got me at most an extra 50hp on my N/A motor could EASILY get me 100hp or even more on the turbo motor. It's definately something to think about.

[SleeperZ]

My bone stock L28ET makes 128 hp/liter.

[Guest InterSpool]

bastaad: This car will be a 240z.

 

Dan Baldwin: Tell me more about Norm's setup and how it costs him 50 cents. I would be happy with mid 13's definitely. I also plan to go mostly junkyard and DIY on this motor so any tips for the cheapest setup with the best power would be great.

[Dan Baldwin]

Here's a search on his username:

http://hybridz.org/nuke/index.php?name=PNphpBB2&file=search&search_author=norm%5BT12SDSUD%5D

 

Norm's results for a NA, pump-fuelled, SU-carbed L28 are, shall we say, atypical. Norm driving the car is probably worth .5sec, 1-2mph. Having Norm tune the car is probably worth a like amount. Figure his basic setup in the hands of your average competent driver/tuner would be in the mid-high 13s at ~105.

 

Norm's basic setup:

L28, LD28 crank, shaved L28 pistons, shaved ported N42 head, ~10.6:1 CR(?), modded bored SU carbs, custom tranny ratios, etc. etc...

 

Maybe he'll pipe in with more specifics.

[johnc]

100hp per liter normally aspirated in the L6 is certainlay attainable. A lot of the GT2 2.8L race engines made 120 hp per liter way back in the 1980s. You might even be able to hit that number on unleaded pump gas if you run a sophisticated engine management system and do some head work focused on detonation prevention.

 

But, as has been said, you'll pay a lot of money to achieve this abstract number. Expect to pay tens of thousand of dollars including the EMS and ancillary components. For a street car a turbo is an easier and cheaper way to make power.

[Guest bastaad525]

Yeah, Norm is definately something else... the problem is, he's like the ONLY one who can run that fast with that setup. You gotta figure he's also done a LOT of work himself, like porting and polishing the head by HAND. That's why I said... if you know what you're doing and have the tools and the will to do a lot of that work yourself you can make a powerful motor for not too much. But if you're paying someone else to do it it gets costly fast. I personally wouldn't try to port and polish a head myself, I simply dont know enough to try it and would probably do more harm than good. Remember also that Norm is driving one of the earliest Z's which I believe only weighs about 2100lbs. '71-73's are a couple lbs heavier. I think Norms #'s can be duplicated but so far no one has found the magic combination to do so.

[Tony D]

100HP/Litre on his last dyno runs before Bonneville last year.

At the rear wheels, Normally Aspirated.

L28 bored .040", L28 Crank, no stroker.

Built in his home garage.

EFI makes it idle nice...

 

wow, I can log in again....

[Guest zcarjunky]

My N/A L28 makes a little over 100hp/litre. My CR is somewhere in the mid 13's (engine is fully broken in now). I do NOT however run pump gas, and it is no where near stock. Tripple weber DCOE 48's custom cold air intake. Comp cams semi racing custom grind. Beehive titanuim valve springs. Custom built dual 3-1 headers, runs true 2.5" duals through 2 cats and into a flowmaster dual inlet racing can, then out through 1 3" tip.

 

All told I have over 20K invested in mechanics alone. If you have the money, there is a lot you can do.

[olie05]

...As far as "old-tech"' date=' dohc multivalve isn't much newer tech than SOHC 2 valve... [/quote']

Actualy I thought the whole reason why zcar heads suck in performance compared with newer multivalve heads was because of the cross flow principles involved. In those newer engines they have the path of the intake and fuel charge planned up to the spark plug and out the exhaust.

 

Furthermore a 32vavle head setup on a v8 will easily add 100hp, if not that then more, so if a stock l28 block had a 4 valve per cylinder head on it, it would produce at least a 75hp increase over a stock datsun head.

 

To sum it up, Isn't the poor head design the most limiting factor on the z car engines?

 

I forgot one thing; If you had all this head stuff flowing better than the stock head, (4 vavle crossflow setup) the way the intake charge moved would actualy allow you to run a higher compresison ratio than normal without detonating early, and in the end give you more power. of course this would be some crazy engine:

I-6 with dohc 4valve per cylinder crossflow head running 12-13:1 compression ratio and of course alot of bottem end stuff too...

[johnc]

To sum it up, Isn't the poor head design the most limiting factor on the z car engines?

 

No. The L6 two valve head can be made to flow very well, with numbers comparable to 4 valve heads of similar combustion chamber size. The limiting factor is what people are willing to pay to hit those flow numbers. Remember, typical GT2 2.8L engines are making over 340hp on carbs so their hp/liter numbers are over 120. If SCCA didn't penalize FI so much (10% in weight) we would see even higher "typical" numbers.

[Dan Baldwin]

Furthermore a 32vavle head setup on a v8 will easily add 100hp' date=' if not that then more, so if a stock l28 block had a 4 valve per cylinder head on it, it would produce at least a 75hp increase over a stock datsun head. [/quote']

 

These numbers appear to be from a mathematical procedure known as a "brown-hand transformation"

(not that I don't use this transformation quite a bit myself)

 

An OHV V8 and a DOHC 32-valve V8 are such fundamentally different designs, it hardly makes sense to think of just adding a "32-valve setup" to a previously OHV design (though I'm sure this has been done!). I seriously doubt it would be worth 100 more hp, anyway. Some reduction in losses to reciprocating valvetrain, some increased valve area, and some additional rpm might be realized, but I'd bet the theoretical gains would be more like 15% than 33%. And at the expense of much greater engine weight, up high. A big-displacement ohv v8 is a fine solution, if you ask me. Smaller-displacement would want DOHC and multivalves.

 

The math used to equate an imaginary +100hp for a V8 (of what displacement? what rpm capability?) to +75hp for an I6 Datsun (~3 liters? 7k rpm? 8k?) might be a little beyond my understanding...

 

4-valve technology is hardly new, Deusenberg's had DOHC and 4-valves per cylinder (and intercooled supercharging!) back in the 30s.

 

Is DOHC 4-valves/cyl inherently "better"? In some ways, (valve area, valvetrain rpm capability) yes. In other ways (cost, size, and total weight), no.

Does the L6 "need" a dohc head and 4-valves per cyl to perform well? For me the answer is "not really".

 

If you look at it in terms of hp/engine weight, I doubt multicam/multivalve arrangements are much better than sohc (inline engines) or ohv (v-engines) 2vpc. In the end, smaller displacement engines need to spin as fast as possible and breathe as much as possible to make decent power, hence the "need" for DOHC/multivalves is greater.

 

Consider GM's LS engines vs. Ford's DOHC "mod" motors. The OHV LS-6 makes 405hp. To get to that power level, the Ford motor needs a supercharger. The Ford motor is MUCH bigger and heavier, with a much higher c.g., and surely costs a lot more, too. I know which one I'd rather have in my Z.

 

Just my rambling thoughts...

[Devilcat]

Those L28 race blocks had some big cams somewhere around 300+ duration, all the head work and path shaping. If you look at the exhaust on a moto-cross bike you will see the bulging out for expanded gases helps vacation. Most speed shops have good head gurus but in iron or thick domestic aluminum.

 

The other thing was coatings, every where. Now days the coatings tones better and will help even more with the friction loss. With the right combo you can reduce the friction loss in the engine by 2/3s and about in 1/2 in the tranny and diff.

 

Knowing that the Prince L series block attained by Mr K was based off of Mercedes diesels helps with the CR PSI.

[Challenger]

Just wondering since the L series was based on the mercedes engines, do any of the mercedes heads fit even close to the L series block? Just curious..

[HS30-H]

Knowing that the Prince L series block attained by Mr K was based off of Mercedes diesels helps with the CR PSI.

 

This sentence gets the dubious honour of providing my first internet forum "EEEEK! - he can't be serious!" moment of 2009..........

 

There's so much bad stuff joined up in there that it's in danger of imploding and re-forming as an entirely new universe.

[Devilcat]

The Merced heads will not fit, even if you could find one. The block came from a diesel so there is a lot of cyl wall to bore. As far as the "Price L series" line that comes from Mr Ks book, sorry for the bad resource. Be warned HS30-H I have a dead Welsh grandfather that haunts.

 

"Better to live a short full life as a smartarse than a long dull one as a dumbarse". - AC Ellis