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[quote=”Evil-i” post=189911]I don’t think there’s a “carved in stone” answer to your question. Something that has real-world benefits for a particular engine may not do anything for another engine. Another person’s experiences won’t reliably predict what you’ll experience. You’ll simply have to experiment and see what the results are.
Your engine’s volumetric efficiency and swirl within the cylinder will have an effect on detonation. Likewise, the efficiency of the entire cooling system will have an effect on detonation, since, at the heart of the matter, the root cause of detonation is simply too much heat within the cylinder and combustion chamber for the fuel to handle.
One concern for me in your question is that you say your friend has access to better fuel than you have. If your fuel quality is sketchy, detonation will likely be an issue, especially at 12:1 compression. Rather than messing around with valve timing, perhaps running a lower compression ratio will keep detonation away. On the other side of the coin, you could always use an octane booster, but that is a never-ending expense, and a bit of a hassle, since you’ll have to measure and add the appropriate amount every time you visit the pumps, and you won’t always be adding the same volume of fuel to the tank.[/quote]
Thanks for your answer. I already considered both lowering the compression ratio and using octane boosters. But lowering the compression ratio would mean a complete rebuild just to revert to a less powerfull spec. So is a last resort move. Then you clearly explained why octane boosts is not a nice solution.
So I know running higher compressions like 13:1 is achivable, maybe you lose drivability but thats not my concern right now. Usually people use high CRs with performance camshafts. But what im trying to understand here is the physics behind that at high rpms.
Well guys, appreciate the help, finally changed the master cylinder (again) pedal freeplay and pedal feel changed massively with the new master, i drove it for some miles and a few days now and everything seems ok.
So i will say its solved.
Thanks for the answers.
I compared both new and old clutch and were identical.
Still before start taking all apart I would like to understand why the pedal is so akward:
First and foremost the pedal doesnt have any freeplay, the engagement point is just at the point I release the clutch. Also the pedal has a adjusting bolt that act as a stopper for the pedal.
Thing is pedal is not returning to the point the stopper is, even if i turn all the way down the adjusting bolt the pedal doesnt raise enough when released to touch the adjusting bolt.
BUT just for the sake of trying i more or less bled dry the system, with only air in the system the pedal returns all the way up to the stopper when released.
My theory is that as the engagement point is so high, when fluid is cold pressure plate can engage the clutch fine, but as fluid and maybe also air expands when hot the pressure plate is still pushing the friction plate a little bit enough to make it slip when load is applied.
But I cant figure why is this or whaterver is making the clutch slip happening.
When the car is cold I can put it at 2500 rpm in 5th gear, push the pedal to the metal and the clutch will not slip a bit and the speed will go up inmediately, after a few stop and go traffic i cannot even press hard in 2nd gear because the car will slip madly.
I hope i made the problem more clear now.
[quote=”Entangled” post=184524]I’d suspect obstruction somewhere in the coolant flow. If the top radiator hose gets hot and the lower never does, it’s likely a matter of coolant not moving in a loop. Obstruction within radiator, obstruction within block / head, or water pump impeller issue. I’d try pulling the thermostat and running water from a garden hose with upper radiator hose disconnected. Using the upper hose as a funnel, you can force water to flush through the circuit either down through radiator as normal, or down through block in reverse. I know the water pump is likely driven off the timing belt and difficult to access, but with the system full of water and radiator cap off, you may be able to see a surge in the radiator neck when the car starts. That’s a good indicator that the pump has put coolant in motion of circulating, provided there isn’t an obstruction preventing it from doing so.[/quote]
well water pump is driven by the timing belt. I did the water hose thing, poured water from the upper hose and it came out through the thermostat housing. poured water from top of the radiator, came off at the bottom without issues.
im going to throw something here, this engine has just been rebuilt, i mean less than 500 miles since new rings were installed, so i guess some overheating from the extra friction of a rebuilt engine is kind of expected. but i think what i have is too much. maybe im wrong
is there a way to check if the water pump is ok? I mean i can remove it but that wont tell me if it is moving the coolant correctly… I think i need a way of testing it in action. as I said before, i have good heat coming of the heater so at least one would think that water is circulating i guess… i checked and all the fins are ok, its a metal one, not a cheap plastic pump.
Im leaving here some diagrams of my cooling system so maybe someone can spot something i couldnt.
did a power balance test? is the iddle speed ok or a bit low? if u rev it too like 1500-1800 rpm the shaking goes off?
[quote=”Entangled” post=184484]What signs are showing that the engine is overheating, just the scan tool data? I’d imagine that by 248F, the radiator cap spring should be open and venting excess pressure to the overflow bottle. Anything strange happening there?
I’m confused as to how the upper radiator hose could be hot once the thermostat opens, and yet the lower hose doesn’t warm up. If your coolant temperatures are approaching 250F coming out of the thermostat housing, it surely can’t be transferring all that heat to the radiator and coming out the bottom hose lukewarm. You should be seeing 185-200F into the top hose, and dropping approx. 10F by the time it gets to the lower hose.[/quote]
Thanks for your replies.
Ok, signs of overheating are yes the scan tool data, the fact that it reaches working temperature SUPER FAST and even with the hood closed you can feel the heat coming out of the car and it didnt happen before, also as I said, once fan turns on, it never turns off again, and in the past it did.
The overflow bottle: never seen many action at all there. Its hard to see the coolant level when the car is hot cause more or less u have to put ur head in the way the fans are but never see any change in level there (and I marked the level when cold with a marker so I could see if there was a leak)
As to the hoses im puzzled, cause it was my first thought, thermostat. I removed the thermostat, tested the old one and the new one in hot water, both opened at the same time both are the correct graduation for the car: 180F
STILL i get the feeling that water is not circulating from the temperature of the hoses.
@relative4: if u mean obstruction like something preventing airflow, im sure its not, the car has a very big mouth in the bumper (there is a version with intercooler of this car) and is clear. If u mean obstruction internal, when I drain the coolant I do it from the valve at the bottom of the rad and I can see the coolant flowing from the top of the rad so i guess no obstruction there.As additional information. Its summer here.. about 90F all day long.
Well finally got my hands on a compression tester.
Cyl 2 3 4 about 120psi
Cyl 1 50 psi 🙁So a leak down test is in order I think. Now I need to get my hand on a tester.
I ll keep you guys posted.
Thanks for the reply. As I wrote I already checked sparkplugs and wires for that cylinder. What else in the ignition system would cause a single cylinder misfire? Is a two coil wasted spark system. Maybe I missed something in the FAQs.
Thanks
EDIT: Reducing the gap in cyl1 sparkplug by about a 40% make the engine run a bit less rough. Does that make any sense?