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Hi Fred, currently I have put back the intake spider and just need to install my FD with the FD injection lines to the injectors.
I noticed that when putting back the intake (air mixture body), it touched the belzona-kit layer. Apparently at some places it was too thick (>3mm)
So I removed a bit with my dremel.
There is really not much space in between..
I saw it and contacted the guy. Very friendly. I checked the engine and discovered loss in compression so he would check it further out. But he will soon receive other M28.21/22 engines...
Important to me for such a used engine is that compression of each cilinder is good.
In the meantime I had a chat with another very friendly and skilled guy from Garage De Loods in the Netherlands : he told me no to weld the huge crack in my engine. it will be very hard to weld and eventually you'll end up with the same issue...
Better would be to find a good shortblock (with minor damage to the cilinders) and put steel sleeves. Apparently he works with someone who has over 25 years of experiences with putting sleeves in aluminium engines.
The advantage (compared to new alusil coat and oversize pistons) is that you can reuse your pistons, and that it is cheaper ...and you can also replace the sleeves when they are worn.
Usually, steel sleeving an iron block is a poor compromise.
From one of the 2 preminent water cooled 911 engine builders in the world (Baz at Hartech), here's why....
"Classic mistakes
(1) If an interference fit is used then every time the alloy block expands it does so twice as much as the steel/iron ferrous cylinder so with the pressure from the head pushing down it gradually lowers the liners at the top and the head gasket design is insufficient to take up the difference (and that’s if it was fitted properly which this one wasn’t).
(2) If an interference fit is used with Loctite the pressure as the liner is fitted on the Loctite can set it before the liner is fully home.
(3) If an interference fit is not used and replaced by just by Loctite it will not be strong enough to prevent the liner tilting under the piston forces allowing it to wriggle its way down the bore and sit out of square at the top.
(4) If there is no attempt to close the deck by making the liner fit into a precision machined recess at the top then there is little to stop it tilting or even rotating.
(5) Iron or steel has half the expansion rate of aluminium and there is nothing you can do about that.
(6) If you heat up the block to fit the liner so when it cools it has a high interference fit then it squeezes the liner inwards just at that point of interference. Then you bore and hone it cold so when it runs the block expands and the centre of the liner releases its pressure and expands more than the other parts creating a barrel shaped bore – bad for ring wear.
(7) If you reduce the interference fit then when the block heats up you lose that fit and the liner becomes lose.
(8) If you fit it with clearance and Loctite the block expands more than the liner and the Loctite cannot take up the slack – allowing the liner to move.
(9) Finally you have to bore and hone the ferrous liner to a bigger bore clearance (because of the differential expansion) and since you then run most of the time with a relatively cool piston it increases blow by, reduces compression, runs less efficiently and burns oil.
It usually takes some time for these movements to require another engine rebuild.
Why people who should know better continue to use this solution is beyond me.
An alloy liner expands and contracts WITH THE BLOCK and therefore has no problems resulting and has better thermal conductivity (keeping the combustion chamber as cool as it was designed to be).
Nikasil is recognised as the best cylinder coating that has been proven in use for decades (Plasma may one day match it we don’t know yet)
NIkasil on an alloy bore is used in air cooled Porsche’s, GT3’s and Turbos – do you ever hear of them having cylinder problems?
The round shape at the top of the block is ideal to fit the top of a liner into so it is additionally supported (cannot be a bad thing) but them you would have to start off with bigger liners and do more machining of the liner and block.
We do all of this and have made and supplied over 10,000 Nikasil alloy liners without any problems over the last 20 years and you have an agent of ours in Calgary who can do that for you – Alpine Autowerks – it seems a no brainer to work out what to do next to me!
Baz."
The only guy who seems to have really good success with steel sleeves, at least in the 911 engines is Jarno. If he's the "someone" then that may be a decent alternative.
Hi Fred, currently I have put back the intake spider and just need to install my FD with the FD injection lines to the injectors.
I noticed that when putting back the intake (air mixture body), it touched the belzona-kit layer. Apparently at some places it was too thick (>3mm)
So I removed a bit with my dremel.
There is really not much space in between..
Gerrit,
We noted the clearance as a risk during the preamble- that you got it so close and only needs a small trim is a good testament to your careful attention to detail.
That or you are very lucky in which case get some Euromillions lottery tickets quick!-
dammit Gerrit , get a new block.... how can you ever drive it without worry ... ?
Well, I found a guy who is swapping his engine M28.21 end this year with a new one and is willing to sell it to me his engine... it is a used engine but with good compression.
Since I am not using the 928 on a daily basis, for me a good used engine is OK.
In the meantime I started my engine today after almost 2 years not running and I drove for about 40 km ...what a pleasure when you hear the engine roar :-)
Engine runs great.
Till now no major leaks at the crack....but ofcourse it's just a patch to be held till end this year.
I suspect the 2 component kit will not held sufficiently since engine really gets hot....
I bought a new one a week ago. 5850 €. I think it was a very good deal. I have two sets of heads so it‘s easy to compete.
This one was old stock from Porsche who bought a free Porsche dealer in a package 5 years ago.
New S2 bottom end with full gasket set Just bought this! :-)
That´s not the plan....
The plan is bringing the moosgreen 85 928 S without sunroof back on the road.
I bought the car 13 years ago for 2.000 € with TBF. It´s like good old wine, every year more the car is rising in money.
But the seller has also a new automatic gearbox in the shelf. So my plan was changing the transmission to a 5 speed and I have already all parts.
A complete new drivetrain is also interessting.
I bought a new one a week ago. 5850 €. I think it was a very good deal. I have two sets of heads so it‘s easy to compete.
This one was old stock from Porsche who bought a free Porsche dealer in a package 5 years ago.
New S2 bottom end with full gasket set Just bought this! :-)
Damn Karsten, that is indeed the holy grale :-) Nice deal you've done.
In the meantime I will have the possibility to buy a good used engine (10 years old) from a fellow 928 enthusiast end this year, begin 2023. He is an engine specialist and is often upgrading engines.
I just need to put my mechanical Kjet injection onto a M28.21 Ljet engine. No idea if this is feasible ?
Thx, the short block was over a year on Ebay but no one would pay the price but if you refresh a block with one or two broken bores it is way more expensive.
928 community thinks in prices from 10 years ago.
I think you must change the top end. Use your heads with the K Jetronic.
Thx, the short block was over a year on Ebay but no one would pay the price but if you refresh a block with one or two broken bores it is way more expensive.
928 community thinks in prices from 10 years ago.
I think you must change the top end. Use your heads with the K Jetronic.
05-13-2022, 06:18 PM
