Early Gen III 3sgte thin wall block weakness?

[KiwiMR2]

when talking about early Gen III 3sgte's

i.e. 1993/1994 3sgte

Farmer daves is the latest version of the 3sgte. Im comparing it to the 1995 upwards 3sgte.

Cheers
KiwiMR2

[KiwiMR2]

Looking into it a bit more it seems this theory originated from Fensport:

Toyota have changed the part numbers for the 205 block, they nor TTE or TRD or anyone else will admit to there being a problem on some blocks.
The problem is generally between 2&3 cylinder although we have recently found thin areas at the rear of no4.

A thick wall block will be between 150-160 thou thick, and a thin one will be approx 110 thou.
Now the problem comes when you ask "how thick for how much BHP"
This is not an easy question to answer, my advice is don`t build any block less than 140thou unless its going to be left standard.
Measuring the block is not at all easy, best use an engineer who can ultrasound test the average thickness - I say average as - If you imagine the outer side of the cylinder is not uniform.
450whp is approx 570 flywheel which is big power in my book, I would not use any bigger than 86.25 bore on a thicker type block.

TTE group A blocks are fine, but hard to get hold of, and very expensive as you`ll need special pistons as well, the block is 3mm lower deck height.

I use a standard block as I don`t beleive tte one is the right approach for us, for one they will run out - then what do we all do? For another the expense.

Only last week we rejected two ST185 blocks for rebuild, 1 was 120thou, and the other 110 thou, this was particularily annoying as I thought they were all ok - just shows you trust no-one, and measure everything.....
Hopefully that`ll save some expensive mistakes!!!

Some people don`t believe what we say - they think we make it up to sell blocks - all I can tell you is what I have found - the rest is up to you.

It seems they came to the above conclusion & it spread all over the UK forums like a virus.

It seems they have done a lot of work with 3sgte's...ST205 & SW20 variants, is it possible they might be right having seen some many blocks??

Cheers
KiwiMR2

[anthonym]

A tossup between mods with lesser technical knowledge vs those with obvious attitude problems would see the former win any day. For those on their own hobby horses - get off them, its not helping as things progress here. Since this thread has been hijacked off topic, its now locked and I have moved the 3 useful posts that were on topic to a new topic in tech. Please continue there.

Thanks for finally being honest Ben. As I've previously acknowleged this is your forum and you are free to run it as you wish. However, based on the above and continued inept moderation, I really have no option but to leave.

Andy, the answer to your question is included in the data from fensport, according to their testing even gen II blocks can have "thin walls". Seems like it's down to manufacturing tolerance and even then who knows how accurate their (non-invasive) testing is.

[Mr Revhead]

going by the rest of there info, it seems they maybe reffering to mega hp builds... weak blocks are certainly not a common 3sgte (or any toyota) trait that iv ever heard of before.
i wouldnt let that put you off your goals




*picks up nemisis's toys*

[Dell'Orto]

Yeah, thats interesting, I've never heard of 3SGTE blocks cracking at anything less than ~500hp.
You'd think Toyota would have used one mould for 3SGTE blocks, would seem rather pointless to use 3 or 4.

[matt dunn]

Mr Revhead,

You know the Ecsort down here with the EX MR2 3SG motor in it,

Interesting fact that they have at least three blocks that the have used that have all cracked.

Maybe there is a reason?

Matt

[Mr Revhead]

interesting.... what power revs they running?

they didnt crack casue of conrods did they?

[matt dunn]

interesting.... what power revs they running?

they didnt crack casue of conrods did they?

LOl, no not a vented block type crack.

They are not making what i would call huge power,
they are running it NA remember. Under 200hp just I think.
And they dont rev it either. After I eventually got the rev counter to run off the MSD they found that they were only reving to maybe 7000.

The were cracks not holes.
One of the blocks they actually run in an enduro as they could not get another in time.

Matt

[fivebob]

going by the rest of there info, it seems they maybe reffering to mega hp builds... weak blocks are certainly not a common 3sgte (or any toyota) trait that iv ever heard of before.

Then you haven't read much about 3S-GTE's, or the racing version the 3S-GT then (I don't call them 503E's because as far as I'm concerned that's just another internet myth). Throughout the production life (at least until the mid to late 90's) there have been spates of block cracking in this engine hence several redesigns.

The problem that has caused this latest internet legend to arise, is most likely caused by core shift and possibly poor quality control, though I should add that a properly run foundry probably wouldn't check for wall thickness variances on every block. However I do not agree that thin walled blocks are the major cause of the cracking that people see between #2 & #3 cylinders, cracks usually occur because of stress risers not material weaknesses, and the area in which most of these cracks occur is notin the areas reported as being thinner than average.

[Mr Revhead]

no i havnt read all there is read about them, thats why i stated "not that iv heard of" meaning im not saying it doesnt happen, just iv never heard of it. until now.
if you have some reading of the "503e" avail id be keen to see it as its not easy to find.

That sort of comment is hardly called for, and not what I'd expect from a more mature member of this forum, perhaps an apology is in order

the comment was meant in semi jest.... his actions were a bit over board.
im sure you saw the way he launched himself into the other thread. a bit uncalled for i (and others) feel. it wasnt my intention to cause offence to nemisis, merely lighten the mood a little. seems i may have failed

as for the moderation, how do you propose its fixed? its not feasible to have mods who are 100% correct in tech all the time, and if they dont know its incorrect how can they fix it? and as i stated before, i think keeping incorrect posts can be useful, when they are rebutted with the correct info. if they are deleted then the same mistakes will keep being made.

and on topic:
you reckon stress risers, so it would be prudent to do some block prep, eg deburring when building a 3s engine? thats if the stress points arnt inside the water jacket.... which would seem the most likely place to me.

[andrew]

Sorry, but I have nothing to add regarding '3S-GTE block weaknesses', so please feel free to skip this post if thats all you are here for

Thought I'd add my 2c before this thread is locked and because to me it looks like there are currently only two (err, one) other forum member speaking up about this.

<offtopic_bitch>

Its not so much a matter of anyone being right or wrong, but people continually posting second hand information as "facts" and having no evidence to back up these facts. Or people commenting on something which they clearly have no clue about. IMO this isn't as much of a problem on the other forums, but the technical forum should be kept for nothing more than factual technical information.

And you don't always need technical knowledge of a subject to pick out the facts from the crap - I don't think a moderator necessarily needs to have comprehensive technical knowledge either to effectively moderate this forum (although that would obviously help).

I bet I'm not the only one here who skips over posts when I see a particular avatar/sig; the signal to noise ratio on this forum is far too low and I now have to be pretty bored before I resort to reading Toyspeed. And when I do, I usually just use the search function to search for posts made by forum members I know to post factual information.

</offtopic_bitch>

Thanks for reading.

[KiwiMR2]

Seems someone else has been "testing" too:


there IS actually a water channel between the two middle bores... its effectively a steam ventilation channel... to prevent a buildup of boiling/steam.

Both gen II and gen III blocks have it

Now.. I have cracked a lot of blocks.. and it may surprise you all to know that Ive cracked both the gen II and gen III block in exactly the above fashion, picture perfect.

Whats more.. Ive cracked it on both cyl 2 and cyl 3! Its not restricted to one thinner wall.

And on top of what, Ive had a block sleeved in both #2 and #3 to remove casting defects etc with high quality iron sleeves.. .and I have cracked THEM too.

This has been a major issue for me over the past few years.. so Ive done a lot of research into why it happens. My current knowledge suggests that it is steam related... because the ventilation holes between 2 & 3 arent effective enough when cylinder wall temps rise too far. You will notice that on all 3sgte blocks, the vents between 2 and 3 are actually different to that of between 1/2 and 3/4. This was revised and improved on later model 5SFE blocks.. but Im yet to put one to the test.

My current motor has been free of cracking.. the solution? 1.3 bar radiator cap... to try and raise the boiling threshold.. and RICH tuning to keep cylinder wall temps down. On top of that, the stock manifold has gone.. removing the tendency to favour #2 and #3.. making them run leaner and hotter

I can go into more detail about any of that if you wish

Cheers
KiwiMR2

[KiwiMR2]

Interesting!

My own personal theory on it was that, as cyliinder pressures increase (ie you run more boost or power), the thin wall eventually collapses. Since the thin part is only at one part of the bore, this tends to form a vertical crack.

Increasing the coolant pressure may help, as this would be pushing against the extra cylinder pressure. So the higher coolant pressure could be making the cylinder wall effectively more rigid.

However, I'm wondering if just putting on the higher rated cap will in fact make the coolant system run more pressure. After all, if it DID increase pressure, this would imply that with the stock rad cap, the coolant is constantly pushing the cap open. If this were the case, we'd have a coolant problem, and coolant would be p!ssing into the reservoir, which in itself wouldn't help the block, as it would probably overheat the engine.

&

That's really strange for it to go in between two cylinders arather than on one of the faces that recieve lateral pressure.

I was actually speaking with one of the technicians for the Toyota factory rally team down here in Australia over Easter. They run a current shape Corolla with a full ST205 running gear swapped into it, including the Gen3 3S. The team was running three cars last year.

He told me they had a terrible time with cracking blocks last year. This was due to a fault in the casting. When they had the blocks Xrayed it turned out that the core was shifted so the bore was much closer to the water gallery on one side than on the other. This was with brand new blocks straight from Toyota.

Apparently they now X-ray all the new blocks.

Cheers
KiwiMR2

[fivebob]

if you have some reading of the "503e" avail id be keen to see it as its not easy to find.

No, I have no info on that internet myth, but I do have plenty on the 3S-GT Though none of it is on the net that I can find.

What I have includes published articles that state that the wall thickness was increased 2mm in 1987 to stop a spate of block cracking (source "History of the Turbo Charged Race Car" author Ian Bamsey) and another that states that in 1992 TRD was still having problems with the engine in 1992, and contrary to the internet myth the engine was still being designed and produced in Japan.

Though not on topic I thought I post some photos of the 3S-GT in case people have never seen one before.

the comment was meant in semi jest.... his actions were a bit over board.

I don't find them to be over board in any way, this forum has never been well moderated, and at some point in time you have to say enough is enough and stop wasting time on something that's unlikely to improve.

as for the moderation, how do you propose its fixed? its not feasible to have mods who are 100% correct in tech all the time, and if they dont know its incorrect how can they fix it? and as i stated before, i think keeping incorrect posts can be useful, when they are rebutted with the correct info. if they are deleted then the same mistakes will keep being made.

This isn't the thread to be discussing this and I can't be bothered wasting my time on this one as it was all discussed in this thread

you reckon stress risers, so it would be prudent to do some block prep, eg deburring when building a 3s engine? thats if the stress points arnt inside the water jacket.... which would seem the most likely place to me.

It appears to be in the water jacket, but as I've not cut open a block to investigate further I can't say for sure what is causing these failures, but given the location of the cracks, thin liners does not appear to be the problem

[matt dunn]

Not wanting to seem stupid or something but..

As I have never had one that far apart,

In the picture with the head gasket in it, What is the item on the left?

Matt

[vvega]

looks liek a dry sump...but i could be wrong

[Mr Revhead]

im gunna say the same thing, cept im sure its a dry sump

certainly a very nice engine....
wish i had the EPC for those....

any more info out there? a search isnt turning up much

matt, maybe you could ask a certain someone, im sure he will have contacts

[Akane]

fivebob, The pictures of the 3S-GT engine (?) you've posted is a form of TRD specially developed racing engine? The piston skirts are awfully short compared to my JE version of a 3S-G piston.

Ever thought of the block cracking because of the side forces, pushing the block into different directions?

[fivebob]

I've go more info but I don't have the books to hand so this will have to suffice for now.

• High nickel cylinder block.
• Forged pistons (single compression ring).
• Billet 4340 chrome moly rods (H-beam).
• Billet steel crankshaft.
• Billet steel camshafts.
• 3 stage dry sump.
• Billet aluminium cam caps (6061).
• Shim under bucket valve train.
• 2mm Steel head gasket.
• Adjustable cam gears.
• Bore x stroke- 87mm x 88.3mm (2099cc).
• Compression ratio 9.5:1.
• Intake cam specs: 250° duration @ 0.050" lift 13.5mm (lobe center 112°).
• Exhaust cam specs: 262°duration @ 0.050" lift 14.3mm (lobe center 112°).
• Intake valve diameter 35.5mm/ stem 4.45mm.
• Exhaust valve diameter 29.0mm/ stem 5.45mm.
• Valve train buckets 33mm outer diameter/ 31mm inner diameter/ 24.65mm total height/ 8.13mm shim diameter.
• Turbo - CT-44R/T (qualifying trim) or CT-44S/T (race trim)

IIRC When used at LeMans this engine had approx 680HP in qualifying trim and 580HP in race trim.

[Wolf_Tm250]

I've go more info but I don't have the books to hand so this will have to suffice for now.

(CUT)

IIRC When used at LeMans this engine had approx 680HP in qualifying trim and 580HP in race trim.

Thanks Fivebob, very good ( and amazing.... ) infos !

BTW, returning to the topic,

AFAIK it's an intended use issue:

all the people that I know that uses this engine for LONG track or rally sessions, use only TTE blocks or stock 3rd gen NOT overbored.

Bye.