Digsy

I just love your logic here.

Loctite 5910 or 5900 FTW (which I think is the black silicone mentioned above). One is designed for application by hand using a gun and the other by a robot but I forget which is which.

You'll be doing well to break the rocker arms on a 2JZ because it doesn't have any.

I'd assumed he wanted to raise the rev limit too because he broke the rocker arms on his 200.

The GE powercurve has already "turned over" by 5500 so extending the rev limit isn't going to get you any more power unless you do something else to make it breathe at higher RPM.

Probably not "option 1".

Its not a First Law Of Thermodynamics violation, though The relationship between the amount of cooling power required to drop the intake air charge and the amount of extra power you can extract from the combustion by stuffing more fuel in with the denser air isn't a direct one. In the same way that using an engine driven supercharger results in a net increase in output even though the supercharger itself requires considerable power to do work on the intake air to compress it. This is just way less efficient. Incidentally, cooling fans only make you feel cooler but they increase the overall heat energy in the room

That was my intitial thought (its not 15000 litres per minute at 5000RPM, though, its 7500 because its a two-stroke ) Thing is, the aircon doesn't have to supply the air - it just has to cool it. I knocked up the attached spreadsheet this morning when I first read the thread. It tells you the amount of heat that would have to be extracted from the intake air in order to drop the temperature on an NA from 35degC (about as hot as it gets in the UK) back down to 10degC. Its VERY simplified but there could (in theory) be a net gain of up to 11hp (extra fueling pro-rata'ed with air density). The cooling power isn't outlandish, either. IIRC most AC compressors are in the 5-7 kW range. I very strongly suspect that it won't be anywhere near as simple as this in real life, though, and I had to take a guess at the mechanical efficiency of the compressor. The effectiveness of the heat exchanger and the extra inlet depression it would create would also have to be taken into account. In short, I reckon if this worked someone would have done it long ago AC power.xls

Vapour pressure curves for water, 50/50 and 20/80 coolant mixes, if anyone's interested. If there is a leak, it will be harder to build up system pressure so even a 50/50 mix might be boiling as low as 110. Also if the system can't build up pressure then it won't vent through the rad cap properly. Hence why I was trying to diagnose what was going on in the expansion bottle.

If there is an engine leak then the level in the radiator might drop while the engine is cold, and certainly will when it is hot (but you can’t check the level in the rad when its hot). When the engine cools it should draw coolant in from the expansion tank to replace the lost coolant, so the level in the tank will drop when the engine is cold, but the level in the rad should be full. This will carry on until the engine has lost so much coolant that there isn’t enough in the expansion tank to replace it, at which point the expansion tank will run dry. If you top everything up (rad and tank) then get the car nice and hot and then park up you should be able to see if the levels in the expansion tank are behaving correctly. Then you can check the rad and expansion tank again after it has cooled down. That may help you pinpoint where the leak is coming from. Normal behaviour is: Check before test / cold: Rad full and tank up to full mark. Hot: Tank above full mark. Cold: Tank back down to full mark. Rad full.

When you say its losing coolant, is the level dropping in the expansion tank or the radiator itself? Does the level in the expansion tank rise when the engine gets warm and drop when it cools back down cold?

I'd go for an inch. Even more if possible on an exhaust section that close to the manifiold.

I must admit I've started to notice this too. My drive home (usually about 8:30pm when there's very little traffic) takes me along a couple of roads where almost every night I find people doing 50 in a 60 and 20 in a 30. I don't insist that everyone drives balls-to-the-wall all the time, but when you are trying to get home to spend a couple of hours having dinner and watching TV before having to go to bed to be up at 05:30 the next day it does start to feel like they are robbing you of your free time by holding you up. Doesn't wind me up half as much as people who see a set of traffic lights on red on the horizon and slow down to a crawl simply so they don't have to actually come to a stop, though. Why the hell do they do that? I've even had people do it when there was an exit sliproad that I needed to take between them and the lights.

Yes. I asked because when I checked replacement alternators for the Supra were expensive, but you might have been able to pick up a regualtor relatively cheaply if that's all that has gone.

Yes it is. Did you do the regulator check, too?

LOL. Yeah, just a bit! 215 F is just over 100 C which is fine.

Hmmm. If your coolant temp gauge is accurate and it went up that high then the coolant will have been boiling its nads off. In fact it will boil at anyting much above 120. You need to fix the leak, refill it with coolant and then check that it runs OK after that.

Here it is: http://www.mkivsupra.net/vbb/showthread.php?285237-Oil-level-cat-temp-battery-and-rear-light-warniing-lamps-on!&p=3609249&viewfull=1#post3609249

If you suspect the alternator is not working (and it sounds like it isn't) then start by checking the alternator itself. THere's a how-to on here somewhere. I'll post up a link when I find it.

It used to be true that there was "no replacement for displacement" but its not any more. There's been a huge amount of development into reducing turbo lag which has been driven by the current trend in downsized engines. Now even tiny engines like the 3-cyl Ford Fox have torque curves that look like billiard tables. The thing about bolting a huge single turbo to an old engine like the 1JZ or 2JZ or pretty much anything else to get a truly biblical peak power figure is that its never going to be properly matched for low down performance, so having a larger engine will get you a throttle response that feels more "in keeping" with the top end, but its kind of defeating the object and the opposite way to the way that OEMs are going. The next step as we move towards the next big emissions target in 2020 will be more gasoline engines like the VW twincharger, or the dual boosted much like the diesels that are starting to come onto the market (take the BMW triple turbo as an extreme example). Then you will have small displacement engines with optimised boosting across the whole rev range. The downside is that mapping the control system is a nightmare and probably beyond what is possible using anything other than a "proper" factory ECU. A company like Bosch will take a year to fully map a modern pressure charged port fuelled engine and you can double that once you start hanging the cutting edge gizmos on it.

I suggested that a few posts back, but he really wants one of those gaskets

Ive done a few sets. I always start out with a low temp and a short time (100degC for 5 mins) and then try them, then increase the temp until I feel them start to give, then keep reheating until they come apart. You soon get a feel for how long to leave them in.

Can we get a picture of the stock fuel rail and the HKS one side by side? Some approximate dimensons would be good too. In OEM world we add extra volume into the fuel rail to offset the effects of vapour lock, which itself is a paradox because I was assuming that the interior volume of the HKS rail would be higher than the stocker?

Heat transfer is a function of three factors, two simple and one complicated. The simple ones are: the surface area in contact between the "hot" and "cold" elements, and the difference in temperature between them. The compllcated one is the heat transfer coefficient (HTC), which is just a number which represents how well heat energy can jump from one to the other. Appropriate figures for HTC are usually looked up in a book or passed down from father to son through the media of poetry and dance Suffice to say that you have a cylinder head which is joined to the fuel rail through two junctions which have a high HTC. but a small surface area (the supports). You also have a junction which has a low HTC but a much larger surface area (the fuel rail body / air interface). I'm hypothesising that on shut down the major castings in the engine will have soaked to pretty much the same temperature - about 80degC. I woudn't be surprised if after a minute these metal temps were virtually no different if the engine was left running or switched off. Interestingly, the specific heat capacity (the measure of the amount of energy it takes to heat up a kilogram of something by 1deg) for air and aluminium are quite similar (0.91kJ/kg.K for aluminium and about 1.00 kJ/kg.K for air) but there is a hell of lot less air surrounding the fuel rail by mass which means it will heat up very fast. Air is a good insulator because it heats up quickly and then doesn't pass that heat on. I'm hypothesising that keeping the air moving over the fuel rail by either natural convection (opening the bonnet) or forced convection (keeping the fan running) will have a greater cooling effect than keeping the coolant running through the head (which in engine geometry terms a very long way away from the fuel rail). The other big factor is the movement of fuel in the rail by keeping the fan running. This will help transfer energy heat away from the rail amd also help stop the fuel from vaporising by maintaining the fuel pressure in the rail. Despite you having discounted the air temp as being a possible cause I think you may have some evidence to the contrary because when the bonnet is open your problem can't be re-created to order. It might be interesting to rig the fuel pump to run on for a few seconds after engine shut down to see if that on its own will also probide a fix. For a practial example, have a look at how a pan or metal tea pot handle is attached. Its usually by a single bolt or several very small spot welds. This is because the small contact area limits the heat transfer from the hot pan to the handle. You could boil water in the pan all day long and the handle would not get hot. This is because the surrounding air can extract heat from the handle faster than the small contact area with the hot pan can supply it. Even though the heat extraction from the handle is less efficient (lower HTC), the larger surface area more than compensates. By contrast, if you played a hot air gun on the handle it would heat up very quickly as the heat could not conduct away from the handle into the pan fast enough through the same small contact area.

That will help, but in terms of engine geography the water jacket is a long way from the fuel rail, and the conductive path into it is quite small. What we really need is a datalog of the fuel rail temp, the underbonnet air temp and the coolant temp to see which are most closely coupled after key-off. :-)