Those who have cracked blocks in the past, a question...

[greeny]

What sort of boost levels are generally considered block cracking territory ?

It's more about cylinder pressure rather than boost pressure. All setups will vary with regards to boost vs power.

Anything over 500hp and you're pushing it, some will crack long before, some will last longer! Can be luck of the draw I'm afraid!

Thanks Greeny, i'm going for more mapping soon, but i'm not sure what sort of boost pressures to map for ?

I'm only running 1.2 bar at the mo, and my tuner asked what boost i'd like to run. I said 1.4 bar (rev2 forged block, with a precision 3431e turbo). I'm not sure whether going higher is chancing it ?

I guess ANY mapping for more power, is taking a risk. But it's just be nice to have an idea.

I don't want to ruin the op's thread here, but advice is most appreciated

I take it you're mapping it on pump fuel? Who's mapping it?

As you say, once going over stock power levels, there's always a risk!

All depends how far you want to push it i guess.

Just tell him to keep going untill he has to stop

[BarronMR]

its all down to a crap design in the block itself.

Lol, yeah those pesky designers not planning for massively increased internal pressure forces and the thermal shock stresses induced by tuning to more than twice the output

[gazrev1tubby]

Lol

I had it mapped at torque developments in Grays, Essex. It's a hub dyno, and they have a very good reputation.

I had a few probs with inlet temps, but i've now fitted a front mount rad for my chargecooler which has made a huge difference.

Also, they had to stop at 1.2 bar as they said the stock map sensor (rev3) was struggling to get an accurate reading. Being a 2.5 bar sensor, it was getting near the end of it's accuracy. I'm going to order an aem 3.5 bar sensor, so they can map for more.

I (foolishly) had it mapped with my nur spec fitted, and left the bung in . I've now fitted a japspeed with no bungs, and my boost seems to be spiking a bit. My Gizzmo is set to the lowest duty possible, and i'm hitting just under 1.3 bar. I'm also getting considerable knock registering on the pfc commander, which is worrying me, but I guess it could be due to the map as i'm exceeding the 1.2 bar they reached on the dyno ?

[2barGee]

Hi mate just up your breakdown cover so you can take the car anyway if anything goes wrong! Or take lots of coolant and expect a long drive home.

I could run Mine as normal with no boost, then boost it up and it would overheat!

Looking forward to your results man good luck

[dawesy]

....early or late block sleeved or not makes no difference.....

You should be ok with a late 3s block, sleeved with the re-inforced corner, or are you saying you have already cracked a late sleeved block?

Did you cement it just to the water pump housing or fully to the deck?Where did you crack the cemented block?

ive had a block i brought brand new in 2003 ultrasonically measured and it was thinner than a 94 block by nearly 0.5mm which may not sound a lot but the walls were only around 3mm anyway.
yeah cemented to the bottom of the water pump.
first cracked block about 2 weeks after mapping (Cyl 3)


second cracked block (cyl 3 again but further round)


the only possible explanation for the second one is ai had a small leak (turned out to be the HCV) for a short time. wether or not this weakened the block im not sure. the second block has lasted for about 5 years and 20,000 miles though

[greeny]

....early or late block sleeved or not makes no difference.....

You should be ok with a late 3s block, sleeved with the re-inforced corner, or are you saying you have already cracked a late sleeved block?

Did you cement it just to the water pump housing or fully to the deck?Where did you crack the cemented block?

ive had a block i brought brand new in 2003 ultrasonically measured and it was thinner than a 94 block by nearly 0.5mm which may not sound a lot but the walls were only around 3mm anyway.
yeah cemented to the bottom of the water pump.
first cracked block about 2 weeks after mapping (Cyl 3)
Image Replaced With URL For Quote http://i80.photobucket.com/albums/j183/ ... 000023.jpg

second cracked block (cyl 3 again but further round)
Image Replaced With URL For Quote http://i80.photobucket.com/albums/j183/ ... C_0311.jpg

the only possible explanation for the second one is ai had a small leak (turned out to be the HCV) for a short time. wether or not this weakened the block im not sure. the second block has lasted for about 5 years and 20,000 miles though

Not had much luck then!

The 2003 block, then sleeved should be a good option if uve still got the block.

[V8Killer]

Mine cracked at 330BHP whilst on boost on the M1. Once i topped the fluid back up i drove a 100 miles or so off boost and it was fine. Anything above a bar of boost it would start overheating again!

I'd be suspect on a late Rev 3 block too. Best to get the walls measured and see whether its within the Toyota specifications (can't remember what they were now though).

Or better still get a TTE block

[RyanRs]

So, does anybody know of anyone thats cracked or 'Broken' a 5sfe block yet?

I am considering selling my bottom end now, its one hell of a bottom end but as its still only a 3s, be a shame to play roulette with its life I am also thinking that using a 5sfe block i could oversize that slightly and aim for 2.3L displacement?! I know ATS in the usa have achieved 2.4L with a 5s!! that would be nice but then i assume you will be back to square one again with thin cylinder walls... :/

Hmmm ... Can i really be ar$ed to spend another couple of grand on the bloomin car tho thats the thing!

[gavinda]

I havent found anyone across the forums, US mr2 clubs etc.
cant find any and no-one has admitted to cracking a late 5s block, im pretty sure hard target have cracked 5s blocks but they run over 1100hp, although this is on methanol so less knock, det etc.
im sticking to stock 87mm bore for security.
your 3s bottom end would pay for most of a 5s

[Century Motorsport]

The best option (other than 5s block) is a late 96+ 3s with sleeves.

I cracked 2 blocks, one was a 94 block that had been sleeved - it pulled the top corner around the water pump off and the second was the 97 block - this cracked between the cyl 2&3 ... I then sleeved that block and it ran happily @ 900hp on several dyno runs and plenty of drag runs.

[greeny]

So, does anybody know of anyone thats cracked or 'Broken' a 5sfe block yet?

I am considering selling my bottom end now, its one hell of a bottom end but as its still only a 3s, be a shame to play roulette with its life I am also thinking that using a 5sfe block i could oversize that slightly and aim for 2.3L displacement?! I know ATS in the usa have achieved 2.4L with a 5s!! that would be nice but then i assume you will be back to square one again with thin cylinder walls... :/

Hmmm ... Can i really be ar$ed to spend another couple of grand on the bloomin car tho thats the thing!

I've not heard of a early or late 5s cracking apart from rosado, but that's only whats been "said" on the american forums.....which obviously means it must be true

It'd be a shame to not push the 3s to your goal now, and have the down time of sourcing and building a 5s! I'd regret not doing it now you've got everything in place, Just my opinion though!

What size pistons have you got in your 3s? If 87mm+ remember you can possibly get away with re-using them in the 5s block, if its still on virgin 87mm bores, the rest of the internals will drop in.

Do you know what stroke and bore ATS do for their 2.4l blocks? and what the actual displacement comes out to?

I'm running a 87mm 5s block, with a girdle. If it cracks id expect it to go on the bores, if it does it'l get sleeved, and then if it cracks......it'l get binned!

[dawesy]

does any one know if the hks stroker kit fits into a 5S block?
got chance of a fully built one in a rev 3 3S (very good spec and price), its one i helped a friend put together and its never been run (big change in financials meant he cant carry on with the project).
now if i have this ill grout it and still run evans in it, but if the inevitable happens it would be nice to get a 5s block and drop everything in

[greeny]

does any one know if the hks stroker kit fits into a 5S block?
got chance of a fully built one in a rev 3 3S (very good spec and price), its one i helped a friend put together and its never been run (big change in financials meant he cant carry on with the project).
now if i have this ill grout it and still run evans in it, but if the inevitable happens it would be nice to get a 5s block and drop everything in

That's what I'm running in mine. Aslong as its still 87mm bore you "may" get away with it. My piston to wall clearance was a little more than I wanted but it runs fine with no blow-by and I was planning to run it a little looser anyway for when I eventually switch my nitrous on that I've had installed for 3 years and never used!

[dawesy]

thats good news. hoping that the extra 200cc will make for a nice flexible torque curve. the engine im hoping to get has piper 262 cams in as well. be interesting to see how it goes.
ill be on the look out for a 5S block now though