My engine freshen up......

[PZG302]

After more than a few years away from racing due to various reasons, the Green Monster is finally getting a freshen up!!!

The motor I ended up with a couple of years ago is an ex rally stroker, Dat2kman, knows the builder of the bottom end having navigated for him many years ago.

The motor when originally built had an E88 head on it, but this was replaced by my N42 head that I had previously used on my L29.

After having the motor on the dyno and it being very fumy it was decided to give the bottom end a freshen up, hopefully getting away with rings and bearings plus a hone for the bores. With the N42 breathing a lot better than the old E88 head, and giving the motor much higher compression the bottom end cried enough, showing signs of distress with a lot of blow by and no.2 cylinder down on compression when done dry and testing good with a wet compression test, as did the rest of the cylinders.

Unfortunately things didn't work out that well, on pulling the motor down I had some good news and some not so good news......All the pistons were broken with pieces being held in by the rings only. The good news was that the capacity was measured to be just over 3350cc when taking into account the combustion chambers volumes as well as the swept volume of the motor.

Some more bad news was that the pistons used are no longer available, so a new set will be manufactured to suit and be as close to the originals as possible in terms of piston height, though I will getting them with a small dish to drop the compression from 12.8:1 back down to something a little better for pump fuel.

The cam has also been damaged so a new 74degree cam will be sourced as will a new set of rockers. Not too much more needs to be done to the top end so I will still be getting a "budget" rebuild.

The plan is to build the motor to the same spec as I had with slightly lower compression from the dished pistons and obviously some new bits for longevity. To keep the motor reliable I am looking for torque more than outright power, which I should get with around 3.3 litres. The cam will give maximum power around 6800rpm and pull from about 3500rpm, so no need for any work on the bottom end.

Hopefully this will be finished in the next couple of weeks and I can get back on the track and hopefully be doing the times the car is capable of and maybe scaring a few of the quicker Z up here. I should leave Dat2kman in cloud of tyre smoke and him not seeing which way I went

[Zedman240]

Sounds good! But 12.8:1 compression... it's a shame Avgas isn't  as easy to get a hold of  like before..drive up to the bowser and fill up. Would love to see a video of your zed running around.

[sexual_sushi]

3.3 litres

Who's doing your new work if you don't mind me asking, I take it they're local? I was originally going to do everything that I could myself, but now I'm thinking I might jsut get Stewart Wilkins to build me one. We'll see.

[PZG302]

Not quite 3.3 litres....Engine builder made a small mistake in checking measurements.....so it is the traditional just under 3.1.....

Piston has been sent away as a sample and the new ones slightly changed to give me a more useable static compression of around 11 to 1, just acceptable for pump fuel.

The engine builder is local and has some very good ideas for Zeds and is doing a few motors for a few of the guys around brisbane. We were looking at different rod and crank ratios this morning and came up with some very interesting hypethetical builds for L28's and L26's that would be hand grenades but interesting to see what they would do.

As for a Stewart Wilkins motor, a lot of dollars and also a logistics nightmare when he's Sydney based for the initial set up and tune, though I would like to get one.

If you're serious and want a motor good to go, buy John McKewons race Z that Dta2kman put on the forum, Stewart built the drivetrain for that car originally.

Hopefully the rebuild will be finished in the next couple of weeks

[.]

3.3 litres

Who's doing your new work if you don't mind me asking, I take it they're local? I was originally going to do everything that I could myself, but now I'm thinking I might jsut get Stewart Wilkins to build me one. We'll see.

Try Jim Milner at Stafford. Its hard to get his time but I hear the results are worth the wait.

[PZG302]

Try Jim Milner at Stafford. Its hard to get his time but I hear the results are worth the wait.

That's who is building my motor.

Time wasn't a problem, just need to work in with him and the current work load. I was supposed to have my motor ready for the 1st March, but the problems we have had with the bottom end, broken pistons necessitating custom built replacements, and the cam and rockers has blown the time out by a few weeks.

He will build the motor you want and one that will work, won't be the cheapest around, but from my experience so far, he is very knowledgable with the L series motor and knows how to screw them together right.

My motor will get back to me run in and tuned so I can hit the track straight away.

I believe the budget we are working to and the total cost will be more than reasonable for the result I am expecting. If my entry at Cootha is accepted, it should be fun

[DatPilot]

any details on the hypothetical builds???
im trying to see what can be done with an original l24e in the skyline.... sorry to verge off-topic

[PZG302]

any details on the hypothetical builds???
im trying to see what can be done with an original l24e in the skyline.... sorry to verge off-topic

Just playing with crank, block and bore sizes and different rods to see what could work if I were to be playing the class game. If something comes of it for me I will let you know

At this stage I am using the bottom end I already have with the new pistons, a hone for the block as it is liveable and I haven't really got the dollars to prep one of my spare blocks at the moment. That will be the next build, done properly, ie bloody expensive!!!!!! The top end will get new cam and rockers and the new injectors put in that I have had lying around for a while.

When it'd finished it should be a very nice grunter that will rev to around 7400, though I will only use around 6800-7200.

[DatPilot]

anything over 6000 rpm sounds fairly insane!!! luvin it!

[Neuby]

Any news on the engine?  Cootha Classic is drawing nearer......

[PZG302]

Any news on the engine?  Cootha Classic is drawing nearer......

Block has been honed, bores aren't the best but we can live with the end result, motor will have some blowby, but nothing like what I had before the rebuild It only needs to last a couple of years, so around a dozen events or so before the next motor is built, which will be one of spare blocks taken out to 89mm and the money spent on the prep as all the bits in the current build will just swap over. We may look at running a funny crank/rod combo to build a real screamer, but only if we can get a decent amount of torque out of it, and also depends on the final theoretical capacity to see what class I would fall into.

Pistons are in the shop and hopefully the motor will start going back together next week.

If all goes to plan I will be giving the Z a shakedown at Lakeside on May 3 with the MX5 Car Club track day.

At the end of the day I would expect to see the same amount of torque as I had with old build, and hopefully around 30-50 more horsepower as I won't be running with broken pistons anymore. So I should have around 170-180 HP at the wheels with teh same very flat torque curve that pulls from 3500 right through to 6000 with max. power around 6800rpm and a safe rev range up to about 7400, with my normal gear changes at 7200 as per the old build.

There maybe some change to this as the pistons that were in the motor are no longer available and the new ones are a slightly different design with a full dish to allow for use of pump fuel with out having to drown the engine with fuel.

[PZG302]

Called into to see how the build was progressing, and I won't be doing a shakedown run on the 3rd May  .

As above, the block is sitting waiting to be assembled as are the pistons and rods. The crank has been checked and polished and good to go back in.

Last time I called in the head hadn't arrived back from the machine shop, but is now back and looking very shiny and new. Nothing much needed doing, just a little clean up of the chambers to get it breathing a little better than what it did.

All going well, I should be looking at getting it back in the hole in the next couple of weeks, and when it get delivered back will be tuned and run in for me so I can go hard straight away at the Cootha Classic, if my entry is accepted, hopefully this year I won't have my entry fee returned......

It will be interesting to see what power it makes and more importantly what torque, though the best dyno is always the stop watch and the track,

[Gareth. J.]

How do they run it in? Would be great to see a small vid if its run in on a engine dyno     

[PZG302]

How do they run it in? Would be great to see a small vid if its run in on a engine dyno     

Basically throw the motor back in the hole, fire it up make sure the timing is about right, no leaks, or anything that rattles that shouldn't etc, then let it run for about 20 minutes to run cam in and also bearings.

Then it's off to the dyno for a couple of hours to tune it and at the same time run it in. As it is a race motor and will only have around 20-30 hours run time, at most 50, before that motor is scrapped and a new block prepared with the current head it doesn't need the few hundred kilometres that a road motor needs. Also helps that the oil is changed before every event, cheap insurance.

Unfortunately, I will be out around Warwick in the Southern Darling Downs when it is being sorted on the dyno so won't know how it goes until I get back from work...

May have to ask and crawl and grovel to get that great bloke up the road from me, who races old datsuns, to help out with some transport and housing whist I'm away.....

[sexual_sushi]

All sounding good Matt. Let me know if you need a hand with anything.

Not sure what I can bring to the table though haha.