The original L24 which came in my car from the factory began smoking a bit, about 8 years ago. I figured it was valve guide seals but I also wanted to rebuild the engine anyway.

The car came with a spare, rebuilt Siamesed-cylinder F54 block L28 when I got it back from the previous owner, so I asked Vinny to swap them out. He wasn't happy with the quality of the L28 rebuild so he "re-re-built" the spare engine (bringing the capacity to slightly over 2.8L), installed a hi-cap oil pump, better pistons & rings, bearings, etc. He then built a deep-breathing E88 head to 10.25:1 compression, installed larger Nissan Competition valves throughout, lightweight valve gear and an Isky .490"/290* cam (higher lift/duration). My SUs got massaged, an electronic Pertronix ignition installed, and MSA 6-into-2 header and Twice Pipes added. An aluminum Champion radiator and hi-volume water pump finished that new L28 engine installation. He reinstalled it after polishing everything that didn't move. He had already re-done the entire suspension and brake systems about 3 years before that.

The result has not been Dyno'd, but is estimated by everyone who drives the car now, to exceed 200bhp (which probably means roughly 170 RWHP).

Well, I said all that to say this:
While I was having a blast driving the replacement engine, Vinny was busy rebuilding the original, numbers-matching 1970 L24 which came in the car from the factory. I told him to take his time and give me a nice performer which he would be proud to drive. Since I already had the L28 in the car there was no rush for rebuilding the old original L24.

He bored and stroked it to 2751cc (167 ci.), making it almost exactly the size of a standard L28 (2753cc). That adds 22 cubic inches (359cc) to my old L24. Lightweight flattop pistons were installed as well, and the short block was returned to me earlier this year, lubed, preserved, sealed and strapped to a hand truck for easy portability.

I gave him my original E31 head and asked him to give me larger valves and seats, increase the compression ratio from 9.1:1 up to at least 10:1 or higher, and to install the same very-potent Isky valve train and .490"/290* cam that he put into my current L28 head. I have another set of roundtop SUs which I will let him max-out, and will buy another current-tech electronic ignition for the engine. I'm pretty happy with Pertronix up to about 6,500 rpm...and there's nothing of any real value above that speed, anyway.

That will effectively give me two L-28 engines, each with roughly the same HP and torque; one with matching numbers to my car. I hope to have the new "L24" engine bench-dyno'd before returning it to the car, and the present "L28" engine chassis-dyno'd before swapping it out. Anxious to see the numbers on both. I expect them both to show a bit over 200bhp at the flywheel, putting roughly 170 RWHP to the ground.

Should make for an interesting 2021.

Frank T

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1970 240Z

Heck yeah it will! You are in for a fun season this year. Awesome!

I'm interested to hear the numbers on the two engines. You've been threatening a dyno session for your Z since I first met you, I'm glad that's finally happening.

When's the swap going to happen? Might be a good time to paint the engine bay if you are thinking you'd like to/need to. I don't know if that's even relevant or not.

Jay

Unsure when I might swap. The L28 only has a few thousand miles on it since I put it in back in 2015, and I don't have any real complaints about it yet. I do prefer to have the original block in there, so that will urge me to replace it soon. Also the rebuilt L24 (now effectively an L28) has zero miles on it and will be fun to break-in! It will take me out of the "modified" class in our car shows too, since it's the original engine for the car. That will leave me with a very functional spare Bedini L28 to sell if I care to. Anybody could use one of those, regardless which Z model they drive. Shouldn't be hard to find a buyer.

Vinny took the opportunity to spray the engine bay (and the underside) with Rhino-Liner when he pulled the engine to rebuild the car 12 years ago. That stuff is made for pickup truck beds and is nearly bullet-proof.

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1970 240Z

The rhino lining answers that question. How do you like the results of that, and how does it seem to be holding up?

I think the last time you mentioned the engine rebuild you were shooting to make it nearly square, like an L26. I also think you were considering having the modified E88 head swapped onto it at that point as well. I think this approach you are taking now will be better. It will leave you with a more valuable and easier to sell engine because it's complete. Also you can enjoy having the numbers engine in the car, but not have to give up any of the performance!

Rhino-Liner sprays on, stays on. It can't be marred or scratched by any sub-nuclear force. I'm glad I have it under the car and it made my engine bay look "better" in my opinion. It comes in colors, altho I don't know why ~ black is appropriate for what it does and where it's used.

You're right, I did want a square bore/stroke, but after discussion it was decided to duplicate the L28 specs instead. A square engine would have spun-up more quickly and held together past the other engines' redline, but the Pertronix would have limited me to about 6500 anyway, thereby negating any advantage. The downside to my decision is that I will only have a single safe re-build (rebore) on the original L24 now. No matter; the car and engine will outlive me, anyway.

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1970 240Z

Gotcha, that makes perfect sense about the ignition limitations. I understand now. I've used pertronix ignitions in the past and have found them to be simple and reliable. I like them.

It'll be pretty cool to have the original engine reunited with it's proper chassis, and running better than it ever has in it's 50 years of life. Quite a legacy, something to take pride in. And with the amount of miles you put on it, and the durability of those old L series I wouldn't be concerned about longevity. That numbers engine will likely live a very long time, especially with just occasional recreational use.

So just thinking about the pending engine swap and dyno testing. Do you have a facility in mind that you plan to use for that? I'm sure many of the places are geared more for modern software tuning, you would want to find an SU tuner.....or bring one with you (Vinny).

Jay

There are several chassis Dyno units available around here, in three towns which I know of. They generally charge about $30 per pull.

The bench Dyno I would use is directly next door to Vinny; they do that for a living and are his buddies. That's where I would get the flywheel horsepower (BHP) readings. Further down the road, Vinny also has friends at a speed shop with a chassis Dyno. Since I would want him standing there tuning for either test, I will elect to run both engines in New Milford, one on the bench, the other in the car. I don't care what it costs; I would even buy them all lunch. This is a once in a lifetime opportunity to test both engines under separate conditions.

We've held Dyno Days in the past and run several of the Zs (including Bryan Little's) on the chassis Dynomometer. My tach was InOp during that meet so I couldn't run my car then. It has never been Dyno'd while I've owned it and I am anxious to get the numbers on both applications. Since both engines are basically the same build now, it will be telling to see how many ponies the drivetrain absorbs btwn the flywheel and the rear wheels. We have always speculated at/abt 15% but that might be just a thumbnail sketch of reality.

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1970 240Z

I'm really interested to see the results. I didn't realize there were that many places really available by you, I'm not sure if any by me. It's convenient that Vinny has one next door! I don't think I'd be able to resist having that done if I ever get to have an engine built by him.

Jay

There are several different chassis Dynos commonly used in the speedshop market today. You have to scout for one which fits your chassis and expected WHP estimates in order to be safest and most-accurate. Many big-truck shops handle 10-wheel diesel tractors, or RVs or the like. Other shops handle pickup trucks, delivery trucks, etc. Those are geared for commercial haulers or Nutso Monster trucks up into the 1500 horsepower ranges. You have to find one which is equipped to handle the size vehicle you want to test. Essentially, your car has to safely fit the chassis Dyno to prevent unexpected "events" (like coming off).

Also, friends have told me (no personal experience) that the same car tested on different manufactured Dynamometers (DynoMite, Mustang, DynoMax, etc) can get different readings from each.

I prefer to judge by the Brake Horse Power (bhp) flywheel method. That tells you the basic power the engine's capable of without any accessories attached to it. That BHP figure is all you're going to get out of your engine in that stripped-clean configuration, without enhancing some items on it (better ignition, bigger cam, higher compression, more induction, etc). In the case of the L-24 that's 151bhp.

When you install the engine into the car and re-attach alternator, exhaust manifold, air cleaners, power steering pumps, air pumps, a cooling fan, air-conditioning compressor, etc, each of those items takes engine power to operate. That's part of the 151bhp you don't get to use to propell the car with; You might be very surprised at just how much power gets stripped off the engine's max available before it ever gets transmitted to your drive wheels.

Pushing the flywheel, clutch, gearbox, driveshaft and differential each consume energy from the total amount available, too. By the time you measure the little numbers of horses you are putting on the road, you might wonder if your math is correct.

It's fun to watch kids buy *this* air cleaner or *that* fan blade or headers or mufflers because it's advertised to "add 10% horsepower" to their engine. They buy a bunch of aftermarket stuff, then compute "10%" to their original BHP for each item purchased, bragging that they now have a total of "X" horsepower, well above the original bench Dyno figure. Nothing could be further from the truth. Their engine was tested on a bench dyno with all accessories removed from it. What ever accessories get placed back on the engine after it's back in the car, only detract from that original BHP figure. True, they might buy some less-restrictive aftermarket items which really do take away some fewer horses than the factory air cleaner (or manifold, or alternator pully, or muffler) but everything they put on their engine only subtracts from the original bhp figure, not adds to it.

There are also 'political tricks' the industry plays with horsepower ratings. SAE (Society of Automotive Engineers), Brake (bhp), Gross, Net, etc are each different ways to measure a vehicle's developed power. Some car manufactures use 'political' horsepower to make their cars seem tamer for insurance purposes. Others (Datsun/Nissan) changed methods of measurement which made their cars sound stronger each year than they actually were.

In the end, all that actually matters is how much power reaches the road.

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1970 240Z