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CBR Jeff

L24 Stroker Build

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Most of this in my build thread, however I decided it would be prudent to have all the information in one spot so that anyone who is interested does not have to hunt through the pages of ramblings that a build thread seems to end up being.

 

Part 1

To Start.

The back story to this build is that I am restoring a 1973 car and have a fairly clear plan for the outcome of the car. The opportunity exists to have it matching numbers so this forms a major part of the build. The gearbox and final drive originally supplied with the care are also being utilised. The car will be used as a weekend driver for trips to the coast, the mountains, regular runs to the Riverina and possible some longer trips.

The plan at the beginning was to build the engine myself but once I sat down and actually looked at what needed to be done to complete the entire project, the time it would take and the costs involved I decided some of the work needed to be farmed out to specialists. This next bit might seem strange and opposite to what many others would do but I decided as I had a great deal of mechanical experience, had built and re built engines, compressors, gearboxes and various other fitting type projects but had limited sheet metal and fabrication experience I would take on the body work and gets some of the mechanical work carried outside by others.

So the key outcomes required from the engine build are

• Reliable

• Fuel efficient

• Start and run with minimum fuss

• Operate from sea level up to 1800m

• In temperatures from well below zero to mid 40’s

• Be responsive and provide enough torque that the car is comfortably drivable

• Most importantly the wife is happy to drive it

• Have a sound that is in keeping with triple’s

• Can be used for the odd track day, touring road events and a hill climb or lap dash.

 

So after talking to a few friends looking at a few options I was set on getting an L24 stroker build underway that was going to be about 2700 cc give or take a bit.

A good friend who I navigated for a long time ago was getting a L24b build carried out by LCR. He had already purchased an option 1 box from Les and it seemed a logical step for him. I knew of Les from rallying in years passed but had only met him once. I decided to have a chat to Les I rang him. My plans soon changed after talking to Les, he spoke about the need to get torque out of the engine to make it more drivable and be able to use more of the gears by bringing the operating range of the engine down in the rev range. We also spoke about the use EFI. So a plan was hatched and the build would start at some stage in the future once the old block and head were delivered.

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Part 2

Starting Point

The original matching numbers motor and E88 head from the 2/73 240z were not fitted to the car when I purchased it. The engine was sat on a wood pallet. The condition of the items was completely unknown but it was a safe bet that as they had been removed from the car and sat on a pallet in the weather, work would be required to return them to service. A new crankshaft was required along with pistons rods and most of the other internals and ancillary items.

I was lucky enough to pick up a set so EFI hardware throttle bodies in almost as new condition for the project. These along with the pallet were shipped to Warragul for LCR to start stripping and confirm that the plan was possible. Les had indicated that while he was confident that the RB crank would fit in the L24 block he had actually never fitted one to the smaller block. Once the block was striped washed down and all of the old parts thrown in the bin an RB crank and rods were test fit into the block to confirm clearances. They fitted just with very very minimal grinding of the internals.

The required parts were ordered and the build was scheduled.

 

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Part 3

E88 Head, Top End

The original head was given all of the usual LCR treatment.

Completely stripped cleaned and prep for modification. The combustion chambers were welded up, ports ported to match the inlet manifold that matched EFI TB’s. As were the exhaust ports to match the extractors that would be used. Valve seats installed etc etc

After this work was completed the head was water blasted and the assembled with new vales. An LCR grind cam to match the use of the car and provide good low end performance and drivability was manufactured and installed.

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Part 4

L24 Bottom End

The block following stripping was subjected to all the usual tests and house keeping before having the cylinders bored to 85.5mm. No machining was required on the block to fit the crank. Rather the crank is machined to fit into the block leaving the block essentially as it was originally apart from the cylinder bore and beck heights, both would have needed to be machined with any build using this block. The RB crank was procured by LCR and sent for machining and made ready for the build. STD connecting rods from a VVTI Production based engine were ordered, believed and made ready for installation. These rods are I beam type, very strong and more than suitable for this build. Special forged Pistons were designed by LRC and manufactured specificity for the job.

Rods and Pistons were balanced and assembled ready for installation.

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Edited by CBR Jeff

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Part 5

Assembly

During the course of a few days all of the components were assembled into the block and the head installed onto the block. Ancillary equipment installed.

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Edited by CBR Jeff

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Part 6

Test Day, Dyno

Finally this day arrived. I had always planned to travel to Warragul to be along for the ride during this stressful, exciting and hopefully enjoyable day. It did take a bit of coordination as I needed to get to Warragul for a day, Les had to be available and ultimately the Dyno to be free for at least two days. So a Thursday early in July was scheduled and luckily all of the bits fell into place. Les fitted the engine onto the Dyno at Power House Engines in Warragul the day before. Ran the engine up and tested it to ensure all was ready for the next day. The day started at about 10am and was finally finished at about 3.30pm. The EFI is being run by a Motec computer. An initial map was installed to get the engine running. Then most of the day was spent methodically working through the rev range firstly at varaible throttle positions then at fixed throttle positioned to complete a table of fuel input rates. As the table came together it was possible to work through the outer edges of the table filling in the gaps.

The set up at Power House Engines is quite impressive. They have a SuperFlow engine Dyno situated in a very well appointed enclosure/room specifically manufactured for the purpose and imported from the USA. John the owner of PHE is a dab hand at running the Dyno and coupled with the tuning abilities of Les make a great team that instilled a larger degree of confidence.

The entire day was a great experience. Just sitting in the background watching people who know what they are doing do their thing is impressive. But when that thing sounds like it does and feels like it does it's a very cool experience. Listening to an L series engine at 7500 rpm if truly an experience.

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Video of part of the day.

https://www.facebook.com/LesCollinsRacing/videos/1820750944826013/

Edited by CBR Jeff

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Part 7

Specifications

Block original L24

Bore = 85.5 mm

Stroke = 89 mm

Capacity = 3066 cc (call it 3.1l)

Compression = 10.57:1

Head original E88

Inlet valve = 44 mm

Exhaust valve = 35 mm

Chamber = 50 cc

Fuel = 98

45mm EFI Hardware throttle bodies

 

Original L24

The L24 was a 2,393 cc engine. Bore is 83.0 mm and stroke is 73.7 mm.

 

Dyno

Max power 305Hp at 6800 rpm

Max toque 260 Lbs-ft at 4200 rpm

Other numbers

At 1500 rpm 184 lbs-ft and 54 Hp

Over 200 lbs-ft from 3500 rpm

Over 250 lbs-ft from 4000 rpm to 6000 rpm

 

Edited by CBR Jeff

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Awesome Jeff!

Thanks Dave but all I did was supply the original L24 and pay the bills :-)

It was Les and the boys at LCR that did the work.

 

Just updated post with a video..

Jeff

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Awesome stuff - I also am keen to keep matching numbers in my car so when it comes time to do the engine I'll be looking back at this thread and thinking about sending the engine down to LCR !

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Comparing an offset ground std L26/L28 crank to the 89mm stroke item Les sells is like comparing chalk & cheese.
Not even in the same league...

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You are looking at it the wrong way, you need to look at the cost differential.

If I purchased the crank you have for sale for $50. I would still need to send that crank for testing, machining, cleaning, polishing etc, so would probably need another $1200 +/- and it is still an L28 crank. Guessing total cost with freight would be about $1300.00. The RB Stroker crank all set ready to go costs between $2500 and $2750 depending on start and finish points. But if you look at the RB crank it's a very different crank.

That's the only difference when building the short engine! 6 new Rods and Pistons cost what they do either way.

Head work, cam, gaskets, timing chains, etc etc all cost the same to, so it's not that much of a cost increase. Admittedly getting it done professionally, including ancillary items and engine Dyno tuning has cost more than doing it myself, but it's done and it runs.....

That's roughly a $1300.00 add if you need help. Money well spent in my opinion.

 

Jeff

L series cranks

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RB crank

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Edited by CBR Jeff

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So after talking to a few friends looking at a few options I was set on getting an L24 stroker build underway that was going to be about 2700 cc give or take a bit.

 My plans soon changed after talking to Les, he spoke about the need to get torque out of the engine to make it more drivable and be able to use more of the gears by bringing the operating range of the engine down in the rev range.

 

Were your initial plans for a 2700cc L24 using an LD28 crank? Did Les have any more comments regarding driveability / torque & output etc of this? I haven't really been able to find any info on this scenario online but have thought about it as a potential option for my original L24. I don't want to increase bore size at all.

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Were your initial plans for a 2700cc L24 using an LD28 crank? Did Les have any more comments regarding driveability / torque & output etc of this? I haven't really been able to find any info on this scenario online but have thought about it as a potential option for my original L24. I don't want to increase bore size at all.

Yes it did but from memory when Les mentioned the RB option I as keen to go that route. LD cranks are getting hard to find and based on what one was being sold for I don't think the cost differential would have been anything by the time you had it prepared and ready for installation. With the RB crank you can grind it for a few stroke options you don't have to go to 89!

As for drivability that's more about fuel, induction, cam and exhaust than bore and stroke.

Talk to Les.

Jeff

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Everything is better about the RB crank apart from the cost, but as highlighted previously the difference is insignificant to the rest of the build. Neither does staying with a stock bore in my opinion. Are you planning on driving 300,000km in your stroker zed?

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Great thread Jeff, most of all thanks for sharing the info, something I wondered about years ago but never had the two cranks sitting side by side. It's great to keep the L series - the best sounding engine EVER. Looks like a nice engine, hope it serves you well Mate.

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LD cranks are getting hard to find and based on what one was being sold for I don't think the cost differential would have been anything by the time you had it prepared and ready for installation. With the RB crank you can grind it for a few stroke options you don't have to go to 89!

That's why I sold my LD28 - I was originally going to build a 3.1 ltr stroker for HS30 00150 - but something else came up (which will be revealed in time) and I decided to go a stock rebuild to keep the budget under control. I also decided to go with an L24 block and retain SU's.

But my car is not about horse power either, got other cars for that sort of thing.

 

The rarity of the LD28 is also what put me off using it, RB cranks are far more available and if anyone complains about it not being an 'original' L-series part, well there is nothing really period correct about the diesel crank anyway.

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Is the RB crank available by itself and what's the go with the flywheel or spacer setup?

 

I assumed it was an LCR only build and no parts available for the DIYer? Unfortunately for me that's not an option, one day I hope so!

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You can just get the crank and flywheel setup (it needs a custom one) but if you are buying a stroker kit worth this much, do you trust yourself to assemble the rest to a high enough level?

You already have the head which is over a third of the cost. I don't think building the bottom end was that much maybe around the 1/3 of the project cost.

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