[Mk2] [Turbo] power

[Ryan S]

Very interesting, i assume we're talking cars upwards of around 400bhp etc?

[porscheeater]

Ok went for a drive this morning and I noticed that the rev counter is jumping! And I mean really jumping (I have a video but don't know how to upload it) but it's not running lumpy at all

There is no rough ideal or anything. What can this be?

[Danbob]

Yeah what's this problem? I'm by no means doubting anyone but 9 years on this site and i've never heard anything about this, if anything i'm slightly worried as my tensioner is off as it rattled itself free

It is based on speculation between a couple engine builders I was discussing the 3S blocks with...we understand why the Rev3+ blocks crack in the cylinders (poor casting, and hence inconsistent cylinder wall thickness, proven across 4 dissected blocks). We also understand why sleeving them doesn't solve it as there is too little material left between the cylinders to resist the forces from the crank, (and so the deck tends to crack into the top water way, typically between 2 & 3).

The history we as a group had pointed at rev 1 - 2 blocks having thicker, more consistent cylinder walls, but when they let go it was almost always around the water pump casting.

One of the speculated causes was that when the a/c was deleted on these engines, often the a/c tensioner bolt wasn't replaced into the water housing, the theory being that centrifugal forces in that area of the block without the additional support from this bolt may have been helping lead to cracking.

It's certainly no where near a proven fact, just our best guess as we tried to explain the patterns in front of us and I'm kinda regretting putting it out there now...expecting to get told I'm wrong!

I'm glad you put it out there!

Just went and checked mine:



No Bolt there - Assuming that's the one you mean - Going to get that sorted out!

Cheers

[ashley]

Bang on mate

[jimGTS]

That's a rather vague tdc mark :-p

[jimGTS]

Regarding bolt, is this a rev1/2 only thing, or effect rev3+ too?
It sounded like it's only 'potentially' an issue on rev1/2?

No a/c on mine, so I imagine no bolt too, worth fitting one anyway even though I'm on a gen3?


Ps, this topic maybe needs moving out this thread??

[Danbob]

That's a rather vague tdc mark :-p

Yeah, it's there from the previous owner, will sort it out before the engine goes back in

[Ryan S]

Regarding bolt, is this a rev1/2 only thing, or effect rev3+ too?
It sounded like it's only 'potentially' an issue on rev1/2?

No a/c on mine, so I imagine no bolt too, worth fitting one anyway even though I'm on a gen3?


Ps, this topic maybe needs moving out this thread??

I agree, this is deffo something that needs discussed in a new topic, I certainly would like more info regarding it, my aircon pulley rattled itself free

[BTWW]

Regarding bolt, is this a rev1/2 only thing, or effect rev3+ too?
It sounded like it's only 'potentially' an issue on rev1/2?

No a/c on mine, so I imagine no bolt too, worth fitting one anyway even though I'm on a gen3?


Ps, this topic maybe needs moving out this thread??

The bolt is there on all revisions.
Non AC engines just have a shorter bolt.

[jimGTS]

Regarding bolt, is this a rev1/2 only thing, or effect rev3+ too?
It sounded like it's only 'potentially' an issue on rev1/2?

No a/c on mine, so I imagine no bolt too, worth fitting one anyway even though I'm on a gen3?


Ps, this topic maybe needs moving out this thread??

The bolt is there on all revisions.
Non AC engines just have a shorter bolt.

i know the bolt is there, im asking if its an issue (not having it) with a gen3 engine as well as the gen2.

[ashley]

The pattern of failures that I am aware of (so very incomplete) suggests that it is a rev 1-2 issue, the casting on rev3+ engines is different, and I am unaware of a pattern of failures around the water pump on later blocks

[decker2]

Thanks Ashley, much appreciated

[jimGTS]

well, what the hey, bolt was missing on mine, so i just fit one for the hell of it, gen3 engine and all.

[Toyspeed]

Im very supprised about hearing (Never heard of Gen1/2 block cracking)?
Im not sure I got this discussion right. But I tought it was understod for everyone. If you pass 350-400hp. You are in the dangerzone of cracking your block?
Almost everyone I know that passed that powerlevel have cracked there block. I have, and I know of 4-5 others here in Sweden. And theres not alot of 3S-GTE MR2´s here.

I also know that there are those pushing 5-600hp with a Gen1/2.
But not even putting the warningflag up there I think is kind of unfair.