Bore torn up by Piston
05-22-2010, 09:11 AM
#31
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Nope, I have never outfitted a stock set up with 4ch EGTs, that’s info from a modified set up (including standalone – but not tuned cylinder by cylinder when those readings were taken).
05-22-2010, 09:19 AM
#32
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well.. my #4 also.. everyone elses #4.. so.. yes, absolutely. always. (99%) number 4 gasket. Rob's and Genes here in Houston (Observed) also.. 2xs minimum each.. number 4. there is a real "cheap"- relatively 4 readout EGT gauge for airplanes out there. $250 for the gauge and you buy 4x $40 probes.. . ONE gauge is nice. maximums and everything. pretty cool stuff..
Click on the INFINITY guages.
TC-1 is what you're going to scroll, or click the pic of after clicking infinity page... check the price.. Do the math... 1/2 price of anything else. Waaaaaaaay cooler too. Oh.. yeah.. thank me now. \\
http://www.mglavionics.co.za/ <<<<<<<<--------------CLICK HERE
Tons of other goodies to oogle over on that website also.
Click on the INFINITY guages.
TC-1 is what you're going to scroll, or click the pic of after clicking infinity page... check the price.. Do the math... 1/2 price of anything else. Waaaaaaaay cooler too. Oh.. yeah.. thank me now. \\
http://www.mglavionics.co.za/ <<<<<<<<--------------CLICK HERE
Tons of other goodies to oogle over on that website also.
BTW - these gauges have peak recall, programmable warning indiactor (it will drive a seperate 'idiot light'), an extremely nice display...
If it weren't for the nice digital dash I already have the other MGL gauges would be all over my track car! I just have the TC-2 for now...
05-22-2010, 09:26 AM
#33
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so what is behind the statement "a 968 piston cant candle boost"" but can handle heaps of NA revs"
sit down and calculate the loads of increased cylinder pressures V increased RPM and also cosider is tensile V compressive load .I guess you can spend years building Porsche engines read clean and measure everything well do a good job but not understand the physics..
sit down and calculate the loads of increased cylinder pressures V increased RPM and also cosider is tensile V compressive load .I guess you can spend years building Porsche engines read clean and measure everything well do a good job but not understand the physics..
Actually there is a valid point to the 968 piston not dealing with ‘boost’ very well in the real world. It can handle the extra load from the higher cylinder pressures just fine (its still way less load than the acceleration forces at TCD on exhaust stroke). But, and a big but, they don’t deal with the occasionally detonations very well and we all know that not everybody gets their tune perfect….
05-22-2010, 09:34 AM
#34
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Its hard to really tell from the pictures - but the lines on the bearings are typical of detonation. Detonation is basically the same as hitting the top of your piston with a 5lb sledgehammer as hard as you can. It will leave marks on the bearings that are thin straight lines in line with the crank near the top of the bearing…kind of like the ones in your picture! If you get into heavy detonation you can squish the bearing a little making little flat spots.
How about a pic of the piston top? We are looking for erosion that looks like somebody was tapping on the piston with an ice pick….
In the case of a turbo or supercharged engine the detonation can be from a lean condition OR high intake temps. Since you are in a fairly warm part of the world (!) the intake temps need special attention.
How about a pic of the piston top? We are looking for erosion that looks like somebody was tapping on the piston with an ice pick….
In the case of a turbo or supercharged engine the detonation can be from a lean condition OR high intake temps. Since you are in a fairly warm part of the world (!) the intake temps need special attention.
05-22-2010, 12:56 PM
#35
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Heres the piston top, a couple of wierd scratches in the carbon, but that might have been me last time I used a screwdriver as a dial gauge to find TDC during a leak down test.
Intake temps during the 10 minute session went from around 100F at the start to 135 F as the car warmed up and just before the failure measured after the intercooler.
Intake temps during the 10 minute session went from around 100F at the start to 135 F as the car warmed up and just before the failure measured after the intercooler.
05-22-2010, 01:33 PM
#37
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Clearly #4 has always had this "condition" hence all the head gaskets failures at #4. Im not so quick to blame the tuners. More so our situation. Air fuels probably AVERAGE out ok. but rich in #1 and lean in #4 is not acceptable.. but the A/F in the up pipe will read the average and look good. So..... I'm going to tune with an EGT at every port. I'm sure I will see whats going on then
Anyone else do done something like this?
Fortunately, with my set up I can tune each cylinder individually.. Another huge PLUS. (Someday I'll get to tune it .. ) SOooooo not sorry I went this route. It did hurt my wallet at start though!..
Anyone else do done something like this?
Fortunately, with my set up I can tune each cylinder individually.. Another huge PLUS. (Someday I'll get to tune it .. ) SOooooo not sorry I went this route. It did hurt my wallet at start though!..
05-22-2010, 02:19 PM
#38
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05-22-2010, 03:00 PM
#39
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05-22-2010, 04:49 PM
#40
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stock 968 motor is now sitting in car. custom header/exhaust/intake manifold YET to be made. So... a ways off.. MoTeC M48 and a bunch of other stuff sittin around.. I have to finish buying panels to finsh tub... I have a bunch of WTB posts right now to charge this project to full speed again. Still.. quite a way out.
05-22-2010, 04:51 PM
#41
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Stock car? I don't know what you are talking about...oh wait, doesn’t NASCAR use stock cars?
Nope, I have never outfitted a stock set up with 4ch EGTs, that’s info from a modified set up (including standalone – but not tuned cylinder by cylinder when those readings were taken).
Nope, I have never outfitted a stock set up with 4ch EGTs, that’s info from a modified set up (including standalone – but not tuned cylinder by cylinder when those readings were taken).
Thank you sir.
PS.. glad you backed me up on the guages.. I will be getting the LC1 Around September... (When motor is ready to burn.) burn money or gas has yet to be seen.
05-22-2010, 05:02 PM
#42
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Trying to sort my own HG issues these days, so this caught my eye -- if the a/f looked fine, what was the issue? Don't mean to hyjack the threat -- PM if you prefer, thanks!
05-23-2010, 12:08 AM
#43
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I'm interested in getting a better perspective on acceptable intake air temperatures. Given that it's nearly alway hot where I am, ambient temps typically between 90 & 125F, and I typically see inlet temps after the intercooler up around 140. Water sprays and injection aren't really practical doing races of an hour or more...
The next engine will be setup to run up to 1 bar boost. I need to decide on a compression ratio to suit, obviously something lower than the stock 968 piston but with my typical intake temps and 98 octane fuel what is sensible?
05-23-2010, 02:14 AM
#44
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I think I need to pay more attention to this issue of high intake temps running forced induction in a hot climate.
I'm interested in getting a better perspective on acceptable intake air temperatures. Given that it's nearly alway hot where I am, ambient temps typically between 90 & 125F, and I typically see inlet temps after the intercooler up around 140. Water sprays and injection aren't really practical doing races of an hour or more...
The next engine will be setup to run up to 1 bar boost. I need to decide on a compression ratio to suit, obviously something lower than the stock 968 piston but with my typical intake temps and 98 octane fuel what is sensible?
I'm interested in getting a better perspective on acceptable intake air temperatures. Given that it's nearly alway hot where I am, ambient temps typically between 90 & 125F, and I typically see inlet temps after the intercooler up around 140. Water sprays and injection aren't really practical doing races of an hour or more...
The next engine will be setup to run up to 1 bar boost. I need to decide on a compression ratio to suit, obviously something lower than the stock 968 piston but with my typical intake temps and 98 octane fuel what is sensible?
Moving your intake out of the engine bay will help keep intake temps as low as possible in your climate.
05-23-2010, 11:52 PM
#45
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I think I need to pay more attention to this issue of high intake temps running forced induction in a hot climate.
I'm interested in getting a better perspective on acceptable intake air temperatures. Given that it's nearly alway hot where I am, ambient temps typically between 90 & 125F, and I typically see inlet temps after the intercooler up around 140. Water sprays and injection aren't really practical doing races of an hour or more...
The next engine will be setup to run up to 1 bar boost. I need to decide on a compression ratio to suit, obviously something lower than the stock 968 piston but with my typical intake temps and 98 octane fuel what is sensible?
I'm interested in getting a better perspective on acceptable intake air temperatures. Given that it's nearly alway hot where I am, ambient temps typically between 90 & 125F, and I typically see inlet temps after the intercooler up around 140. Water sprays and injection aren't really practical doing races of an hour or more...
The next engine will be setup to run up to 1 bar boost. I need to decide on a compression ratio to suit, obviously something lower than the stock 968 piston but with my typical intake temps and 98 octane fuel what is sensible?