L28 block girdle

[luvemfast]

These were once sold here in Australia and sent overseas, before I could reach the pedals of a car. The only reason they became unavailable is personal reasons for the original designer/manufacturer, a family friend of mine. He used to be a well respected racer and engineer, who still holds lap records to this day. While having a garage clean out, he passed on to me the design for me to use and manufacture once more.

He shall remain nameless, as a mark of respect. Life takes you to funny places and he is no longer interested in cars.

Now, his experience was that he DID get benefits from the use of a girdle. He claimed it gave better rigidity in the block and crank, aswell as acting as a bit of a windage tray. Also said that it moved the harmonic vibration further up the rev range, which also changed the sound of the engine. He was a smart cookie and never did something unless there was a reason.

 

After modelling the design on CAD, I have started making small batch runs made from high tensile 6mm steel plate. If there is enough interest, I can make more.

Spacers are required to bolt through to the mains caps, ARP studs or even Unbrako socket head cap screws with hardened washers have been used.

You can see there is provision to drill and tap into the webbing of the block, using countersunk screws. Or if you are using a sump like Arizona Z car's, just bolting that through should suffice.

You can use a modern sealer like threebond instaed of gaskets.

That's about it.

The way I see it, I have spent thousands on parts to make my car go faster, it is a bit of insurance to "look after" my investment!

 

What are peoples experiences and thoughts?

[Xnke]

I have one that I made in college...it's on my block same as yours. I used Grade B7 threaded rod to turn custom length studs, and hardened nuts and washers, when I did mine.

[luvemfast]

No expert opinions on this topic?

I find that hard to believe.

[NewZed]

It looks intriguing but the only benefit that you actually described was moving the harmonics up in the RPM range (even that is kind of subjective). Most of what I've been reading implies that the L6 block is very rigid as designed. Do you have more measured numbers or descriptions of the benefits of adding a girdle? Might generate more interest and discussion.

[luvemfast]

It looks intriguing but the only benefit that you actually described was moving the harmonics up in the RPM range (even that is kind of subjective). Most of what I've been reading implies that the L6 block is very rigid as designed. Do you have more measured numbers or descriptions of the benefits of adding a girdle? Might generate more interest and discussion.

Reduced crank flex is also claimed. More so for cylinder 1 & 6.

How many Z's have s leaking rear main seal?

Original designer claimed the girdle helped reduce these issues.

I'm still in the process of building my engine, so don't have first hand experience.

However, there is one fitted to a race engine here in Melbourne that is getting 193kW's at the wheels.

[Raami]

Hmm... now where have I seen that kind of design before.

Maybe he should remain nameless too.

 

I have been driving my car now for 3 summer and so far no problem... or maybe one set of piston rings only.

[luvemfast]

Hmm... now where have I seen that kind of design before.

Maybe he should remain nameless too.

 

I have been driving my car now for 3 summer and so far no problem... or maybe one set of piston rings only.

No idea, where have you seen the design? Got a link?

As stated, nameless due to respecting privacy. Some people don't like their names posted all over the Internet.

This is aimed for modified engines for track use. Not really necessary for street in my opinion.

 

After some engine builder and/or engineering critique/input?

Usually Braap, TonyD or JMorteson would pitch in, where are you guys?

Edited April 2, 2011 by luvemfast

[Tony D]

It was all said in the previous thread.

Many times an engineering solution is applied that masks other true root causes...

 

You want to add weight to mask a root cause, have at it. Who am I to stop you?

[luvemfast]

It was all said in the previous thread.

Many times an engineering solution is applied that masks other true root causes...

 

You want to add weight to mask a root cause, have at it. Who am I to stop you?

Sorry Tony, but I've read through the other posts found here

 

Doesn't really answer my questions.

The answer

"So much of this stuff is done 'because the other guy did it' and little thought is put toward the actual engineering basis for it!"

 

I think you'll have to spell it out for me......... As I'm just a toolmaker.

Engineering principles, yes.

Race engine build knowledge, no (but working on it ).

 

Taken from an Aussie site, by a respected experienced builder.

The rear main leak is from crank flex. The shaft is moving up and down this is the reason the seal is damaged.

When replacing bearings on big hp l6 engines the mains are normally out of round on 1 & 6 by 3-4thou this would indicate that the crank is flexing through its length.

A girdle will go a long way in reducing crank flex and hopefully help bearing life, as for using an RB girdle this would be a monumental and expensive way around the problem as you would need to line bore the main tunnel which in impractical and the man that built this girdle was no fool and also built some of OZ's best L series long before most of us had Z's or knew how to build motors!

I have found that the arp studs are better but I still had rear main leaks .

Have found that the block brace is a great help at reducing bearing wear and the rear main nearly stopped leaking.

Also I have found that the Arizona sump has been a big help at stiffing up the bottom end as the rails are pretty thick.

Also guys at electromotive ran dry sumps which would help as they would have run vacuum in the sump and their engine would have been rebuilt every time they went out which would help the situation.

 

Hence my confusion.

 

The way I see it, its like saying.

Don't put a roll cage in your car as it adds weight.

Or, Don't bother using forged rods or pistons as the factory units can handle 500hp.

True but the advantages outweigh the negatives.

 

Wouldn't a stronger bottom end give you better reliability/durability?

Not starting a storm in a tea-cup, just trying to learn

[Xnke]

Sure, a stronger bottom end is great. So replace the rod bolts with ARP or equivalent hardware, and call it a day.

 

Unless you're shooting for 500+ HP, no real need to chance much. 700+ is when that block brace starts coming into play, but I can't think of many who've used one and I know there have been L's over 1100HP. It's a stout block, that needs comparatively little prep.

[Tony D]

There is a point of diminishing returns.

And AGAIN, I state that their OPINION on what is causing these items they anecdotally notice is just that. There are alternate OPINIONS which seem to have been equally validated in my independent testing which hold water as to a 'better' source/resolution.

 

They are also making assumptions on E-Motive's engines and what they replaced on a regular basis. What if they never replaced a crank? What if they were running bearings through four races? How does that reflect then on the THEORY that 'block flex' is caused by a crank moving around.

 

Keep in mind that 200 hours on a dyno is equivalent for OEM testing purposes as 100,000 miles++

 

If the Electramotive Engines were 25+ hour 1100HP engines WITHOUT a girdle (and without bearing out-of-roundness issues) I'm thinking most STREET engines pushing half that are well in line...as long as they have the same attention to TRUE ROOT CAUSES as the Electromotive chaps took.

 

What causes crank flex? An inappropriate support structure, or induced harmonics beyond the internal dampening forces available by the crank itself? Perhaps Chris at BHJ can chime in with more details.

 

I posit a stud girdle, while a nice bit of engineering may be nothing more than a band-aid to the TRUE ROOT CAUSE of the 'problem' they think they are diagnosing.

 

And on this:

"Wouldn't a stronger bottom end give you better reliability/durability?"

No, not necessarily. If the stresses present are within the capability of parts to handle them for the duration required, adding more ONLY ADDS WEIGHT AND COMPLEXITY. Look at an F1 engine and tell me how much 'margin' they have... Adding 'durability' beyond the expected requirements is very poor engineering practice. You want what you NEED, and not a single thing more.

 

If this was the case, why not simply put a Stock Chevy V8 in there with 150HP instead of the L6?

 

Oh, waitaminit...people do that...wrong forum to use that analogy I guess...

Edited April 5, 2011 by Tony D