3s-gte Piston Question

[Ian Geary]

Evening all,

first off, I own a rev3 MR2 turbo, but thought I'd pop over to the Gt4 section for some advice.

My turbo, along with quite a few others, has suffered from ringland failure in the past. This is where the spaces between the rings has got cracked, fell apart and led to low compression, a result of detonation most likely. I'm pondering whether to tune my car in the near future, and want to get to the bottom of this failure first.

So, could anyone tell me if this a common problem with the GT4? or just MR2?

I expect the better charge cooling system on the ST205 could well keep your temps down, therefore reducing the chances of detonation.

But if anyone has suffered from this, I'd be interested to know if they pin pointed an underlying cause, and if they sorted it?

The obvious answer is forged pistons and uprated 'cooler, but seeing as boost is standard, the stock equipment should be adequate to prevent pistons from breaking up (I use Shell optimax/ v-power btw)

thanks for any pointers.

Ian

[dawesy]

the problem occurs on the 205 more than the 185 TBH. any thing from duff fuel to a blocked injector can cause it, no 3 cylinder is most commonly affected with no2 second (although i have seen one with no4 cyl kaput. if you run stock boost and turbo then you shouldn't have any problems to be fair, the ST-205 will run upto 1.1 bar happily but beyond that is no-man's land.

as for underlying cause it would seem that its largely down to inlet manifold design with no3 cylinder getting more air, it has to be something that was known about at the design stage as the knock sensor is located at the rear of no3 cyl and it also has a bump to the casting allowing more coolant in the area.

[Ian Geary]

Cheers for that Dawesy,

yeah, it was 2 or 3 (can't recall) that went on mine a few years ago. Didn't realise there was a design issue in the manifold, but I will get the injectors checked out to be on the safe side.

Thanks

Ian

[Jones~32]

Mine went, I decided to go forged

Got a ST205 Charge-cooler setup which is no longer required if your interested? (i'm now running FMIC)

[led-gt4]

Cheers for that Dawesy,

yeah, it was 2 or 3 (can't recall) that went on mine a few years ago. Didn't realise there was a design issue in the manifold, but I will get the injectors checked out to be on the safe side.

Thanks

Ian

mine went in two pistons!!! number 2 and 3 if i remember correctly! i was running standard boost! went the forged route too

[Ian Geary]

interesting..

going forged would be the solution, but I would still have the niggle I'm hiding the problem rather than cure it. Oh well.

The charge cooler setup is tempting, but the extra rad up front is a squeeze in the MR2, and having to remove the core everytime a plug needs changing must get annoying?

And uprated side mount coolers are pretty cheap from the us now - about £250 with the current exchange rate, so I'd probably go down that path for simplicity.

cheers for the offer though, and I admit the water-air unit is technically a better solution.

Ian

[led-gt4]

interesting..

going forged would be the solution, but I would still have the niggle I'm hiding the problem rather than cure it. Oh well.

The charge cooler setup is tempting, but the extra rad up front is a squeeze in the MR2, and having to remove the core everytime a plug needs changing must get annoying?

And uprated side mount coolers are pretty cheap from the us now - about £250 with the current exchange rate, so I'd probably go down that path for simplicity.

cheers for the offer though, and I admit the water-air unit is technically a better solution.

Ian

i havent heard any1 with this problem after forged pitsons. most people go for the rebore after this and that weakens the block a bit. i would say any problems after forged pistons tends to be the block. if u are puttin in standard size foged pitsons then u wudnt have this problem. I would go down the forged route as if u want to up the power then you have a solid starting block.

[dawesy]

yeah the block can be a problem and if your heading for over 450bhp then get some forged rods in there as well. the rolla was pushing 470 on std rods and they lasted for a while but one became a little unhappy. the rebuild is under way and a set of THS forged rods are going in (£360 a set) along with a few other bits and bobs, hope to have around 530bhp when its all together and mapped.

block cracking is another issue and can happen on std engines as well as highly tuned ones, running evens coolant can help.

[Jones~32]

thats impressive Dawesy :D

have you done any cooling mods to help keep the block cool? :)

[GTForbes]

has anyone here thought of trying a side entry for the inlet???

it's easy enough to build one but obviously you cant just bodge one together, a little R&D is needed, one of my mates has built one and is just about broke the 500bhp barrier still running 95RON fuel.

[Jones~32]

500bhp is impressive :)

Whats the spec? B)

[GTForbes]

not sure what you could call the turbo as it was custom made to keep the twin entry system, couldn't even begin to imagine the full list for the spec but here's the !Removed! shot so to speak lol

[led-gt4]

not sure what you could call the turbo as it was custom made to keep the twin entry system, couldn't even begin to imagine the full list for the spec but here's the !Removed! shot so to speak lol

wow! that is the !Removed! shot alright! take its a 205? very nice indeed! clearly had a lot of money spent on it!

but he has left an irn bru tin in there!! lol

[GTForbes]

alot of time and money, the irnbru can is covering the wiper motor IIRC

[Jones~32]

very nice B)

Turbo looks big :D

[led-gt4]

very nice B)

Turbo looks big :D

yea was just about to say that! lol looks like its been nicked of a plane or something. must be 1 of the quickest in the country! ive heard of a 700bhp celica tho. would need a convoy of petrol tankers to follow it tho! lol

[Jones~32]

Yeah, Tony's from Fensport is putting out big power, Rik Parker is also going to be very fast at TOTB :D

[dawesy]

ian smiths is putting out around 623bhp and has a side feed inlet. worth noting that you loose torque as the inlet track is shorter.

the rolla should be around the 530-550 mark when the rebuild is done.

as for cooling i run a TRD stat and evens coolant never see above 84deg even after a thrashing or left idling

[Jones~32]

awesome, im gonna have to switch over to evans I think, heard nothing but good results with it :)

[GTForbes]

very true about the torque dawesy but that car made more torque than the silver fensport 205, ofcourse it made less BHP as always with big power cars it's either one or the other