1zz turbo 1.81L GTK450 updated 19/02/12 pg5

[aaronjb]

 s:shock: :shock: s:shock:  It's also.. y'know.. highly toxic  s:shock: :shock: s:shock:

(Just ask the poor mouse we found in Mark's pit one morning..)

Anyway, glad you got it sorted  s:) s:)

[MR2 super GT]

I didn't swallow.  what I did was remove thermostat pipe, undo bolts, remove the stat.
Tested it in cup of boiling water, very slow to open and didn't look like it was opening all the way. tried it again and it didn't look like moving at all.

connected everything back up, opened heater bleed valve and radiator bleed valve and started topping up reservoir. started engine and closed valves. repeated until it was flowing coolant. massaged the pipes etc.

Thermostat pipe was warm which it hadn't been before. took car for a spin and the difference is major   s:crazyeyes: :crazyeyes: s:crazyeyes:  

it was a cold damp night so cooling would be bit more efficient than on a hot day but the temp actually drops if I put it into 5th and cruise.   s:) s:)

[aaronjb]

I didn't swallow.

That's what she said.

Sorry I couldn't resist..

So are you running with no thermostat now?

[MR2 super GT]

I knew someone had to pick up on that lol. That is right Aaron I'm running with no thermostat now.

[Tem]

I'm running with no thermostat now.

Be careful.

Thermostats are like they are, cause they are designed to create some resistance, which in turn will slow the coolant and create higher pressure between the water pump and the thermostat, which in turn will raise the boiling point, which in turn is pretty important inside the channels in engine. You often lose cooling capacity when you remove the thermostat and tend to lose power as well, or even cause knock. It's not uncommon to overheat the engine by removing the thermostat, while the temp gauge reads normal.  s:? :? s:?

[ChrisGB]

And you can end up with cavitation around the water pump vanes which will erode them quite quickly at high RPM.

Chris

[MR2 super GT]

I will keep an eye on it. if I need to up the pressure I will swap to an electric pump or ad a booster.

How could it overheat if the temperature gauge reads normal? I have my sensor on the head coolant pipe.

[Tem]

How could it overheat if the temperature gauge reads normal? I have my sensor on the head coolant pipe.

You sort of answered yourself already. Because the gauge only reads coolant temperature and doesn't know a thing about engine temperature. It's actually a very bad way to measure engine temps, but it's a cheap and ok average indicator for stock systems. Kinda like you tried to measure your body temperature by measuring the water temp on the floor when you take a shower.  s:lol: :lol: s:lol:  

If we go into details, the lower pressure causes coolant to boil longer at hot engine spots. When that happens, you get air pockets between the hot engine parts and coolant and because air is pretty good insulator for temps, the heat stays in the engine and doesn't get into coolant. The engine stays hot, coolant doesn't get heat and the gauge is happy. Those hot spots often tend to cause knock.

Just be careful with it.  s8) s8)

[ChrisGB]

The backs of the quench zones are classic boil up spots!

Chris

[MR2 super GT]

If a restriction was put on the coolant pipe just after thermostat housing that was equal to having an open thermostat that would work right?

Just take a little longer to warm up from cold start as no thermostat present. Currently the cars temp shoots up when I get over 4000 rpm, that's due to water pump cavitation right?

[ChrisGB]

The key thing here is getting the temperature right. The amount of flow will need to be different for every running condition, so it is not really a good idea to run without a thermostat.

If you have forged pistons, good temperature control becomes even more critical as the temperature differences in the block can lead to poor piston fit and forged pistons suffer more than cast for this.

4000rpm sounds a bit slow for cavitation, but if the coolant is never getting warm enough to pressurise, it could be a problem. Are you sure you have got all the air out of the system?

I would advise getting a stock stat in there asap myself as running an engine with big temperature fluctuations cannot be doing it any good. The dash temp guage is pretty crude and if it is shooting up, I would worry about just how hot the engine block and head are getting.

Chris

[philster_d]

You are not the only one, I was expecting much more from the newly overbored and built engine as well. In fact when i picked it it seemed to have lost a little power from before.

[MR2 super GT]

wow has it been that long. thats depressing  s:-( :-( s:-(

over a year to get the new engine built...
a used block from MWR using the 79.5mm pistons this time and opting not to go with the darton sleeves.

main differences on this build:
GTK450 Turbonetics turbo
TIAL wastegate
cylinder head ported and polished with larger valves
removal of VVTI and installation of a custom made adjustable pulley in the intake cam (pic below)
(edit - the overheating was the headgasket, possibly due to 3 things, stuck thermostat, cylinder sway or insufficient clamp load on the head)

[MR2 super GT]

progress is slow as molasses
New turbo and wastegate finally all installed




hope to be up and running the engine in by 11th December...

[chopper]

Dude i'm in Dublin and when shes done i love to come and take a look so keep me posted if shes running

[MR2 super GT]

Just running the engine in on mineral oil for 2000miles.

here are some pics of the new seats and setup   s:) s:)  

Running Toyo 888s now


Sparco Evo Carbon in red

[MR2 super GT]

Tial V44 wastegate


Larger intake piping than the last build due to bigger turbo. Pipe work goes into a BCM O.T.A. (oval trupet airbox) which is connected to a NACA duct on the rear 1/4 panel

[MR2 super GT]

Just a wee bit if work recently as I got round to fixing the panel gap between bumper and bonnet then got them properly painted. Rest of the bodywork is still just the gel coat from when the kit came out of the factory. Here are some pics from trip to Crail last month for a bit of drag racing. 4 of us drove over from Belfast






After months of putting other things higher on the priority list I finally got some carbon sheets at £60 a pop.
After 2 year I finally covered the eyesores that were my bare doors
Before:


After:

[Stifler]

Could I ask what the name of the steering wheel is and where you got it?  I'm after something smaller than stock and more like my Elise's wheel.

Cheers  s:) s:)

[tomaky]

Ooosh

[MR2 super GT]

Hi stifler

It's a sparco 300
Demon Tweeks

[Stifler]

Much obliged - thank you  s:) s:)

[Anonymous]

Question for you. Why go from 1.96 to 1.8??

[MR2 super GT]

Had to.
1.96 blew head gasket possibly due to insufficient torque on the head bolts.

The block had been bored out to its limit so had to build a new one. Decided not to put the Darton sleeves in with this build

[Anonymous]

What turbo pressures were you running at the time and power output.