S4 engine build thread, some cool pics
02-26-2008, 10:40 PM
#46
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Thread Starter
02-26-2008, 11:15 PM
#47
Nordschleife Master
Hey Brendan, how much did those dissy covers cost you, and would you be interested in having another set made?
I am enjoying watching everyone else post there large projects on here.
I am enjoying watching everyone else post there large projects on here.
02-26-2008, 11:34 PM
#48
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I have to look. I think was 150 for both, but I will try and check back.
02-26-2008, 11:56 PM
#50
Three Wheelin'
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Well, the way I had it down (and I am being careful to not make factual statements here, as you guys know your ****, and will call me out if I am wrong) is this:
I know these pistons are cast. I know that they provide, with the chamber, a higher CR than is usually allowed when someone talks about high pressures. Combustion pressures create heat, and heat creates a situation with pump gas that allows pre-ignition and detonation, which can create combustion pressures (since the piston is still on the way up) up to 10 times higher than normal. 10 times! Thats what blows up engines.
It is my understanding that this is what destroys engines.
Now, take that away. Take the detonation away, take the pre-ignition away. Put a fuel in there that has a slow burn that also cools the final combustion temps because it starts out cooler. It is about 108 octane, but because of its higher Latent heat of evap, its dynamically higher.
So for these reasons, and for experimentation and some budget/time constraints, I am going to run this block as stock as can be without being stupid about it. I have used coatings, 951 rings, forged (well, as forged as the porshe parts get), girdles,S3 cams, and cometic head gaskets to get the engine as ready for pressure as possible.
Past that, if the thing blows up from sheer HP, then thats fine. But I will not let this thing blow up from Detonation, because thats just a waste. 10 times the normal pressure at its highest peak is possible with detonation and pre-ignition. That means if you have enough pressure in the chamber to make, say 700hp, then if it detonates, you get 7000hp. No engine here will survive that nor are the built to. Control the ignition process, and it stays together it seems.
I know these pistons are cast. I know that they provide, with the chamber, a higher CR than is usually allowed when someone talks about high pressures. Combustion pressures create heat, and heat creates a situation with pump gas that allows pre-ignition and detonation, which can create combustion pressures (since the piston is still on the way up) up to 10 times higher than normal. 10 times! Thats what blows up engines.
It is my understanding that this is what destroys engines.
Now, take that away. Take the detonation away, take the pre-ignition away. Put a fuel in there that has a slow burn that also cools the final combustion temps because it starts out cooler. It is about 108 octane, but because of its higher Latent heat of evap, its dynamically higher.
So for these reasons, and for experimentation and some budget/time constraints, I am going to run this block as stock as can be without being stupid about it. I have used coatings, 951 rings, forged (well, as forged as the porshe parts get), girdles,S3 cams, and cometic head gaskets to get the engine as ready for pressure as possible.
Past that, if the thing blows up from sheer HP, then thats fine. But I will not let this thing blow up from Detonation, because thats just a waste. 10 times the normal pressure at its highest peak is possible with detonation and pre-ignition. That means if you have enough pressure in the chamber to make, say 700hp, then if it detonates, you get 7000hp. No engine here will survive that nor are the built to. Control the ignition process, and it stays together it seems.
Full Disclaimer: I'm not one of the guys that knows their ****. I merely read things, think about them critically, and then if they stand up to examination: copy them, and try to remember them - for someday I will use them.
FWIW: the tech articles I have read refer to detonation as a near-instantaneous explosion rather than a controlled burn, and the resulting shockwave breaks things. Lots of variables: dynamic compression ratio, component temps, fuel-air mixture (lean/rich, homogenous, stratified, compressed, swirling, and at what temp?), valve timing, spark timing, load, atmospheric conditions, so many things can add up to BOOM.
The only true way to "handle" detonation is to avoid it. I learned this from my Mazda rotary friends: one little ping in a Wankel and the brittle apex seals shatter, instant zero compression and possible gouging from the scattered pieces.
So you're on the right track. Avoid it. Build and tune with safeguards in place.
I think you've done your homework, Brendan. The combination you've put together should be very stout. I bet you're going to be cautious as you tune it, slowly turning up the boost. And then you're going to proudly post either a heavy-hitting dyno chart or a "WTB: beefed-up tranny, dif, and axles" thread.
- Josh
02-27-2008, 12:43 AM
#51
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Thread Starter
Attachment 257855
This is what ProCharger use's as a guide
This is what ProCharger use's as a guide
02-27-2008, 12:55 AM
#52
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Thread Starter
I found this, from http://www.sdsefi.com/techocta.htm
We have seen that there are limits on what can be done running pump gas on an engine with a relatively high compression ratio. High compression engines are therefore poor candidates for high boost pressures on pump fuel. On high octane fuels, the compression ratio becomes relatively unimportant. Ultimate hp levels on high octane fuel are mainly determined by the physical strength of the engine. This was clearly demonstrated in the turbo Formula 1 era of a decade ago where 1.5L engines were producing up to 1100 hp at 60psi on a witches brew of aromatics. Most fully prepared street engines of this displacement would have trouble producing half of this power for a short time, even with many racing parts fitted.
02-27-2008, 12:56 AM
#53
Nordschleife Master
Keep in mind that Procharger sheet is probably based on a carbed car, with no ability to control spark advance/retard, and perfect AFRs.
Brendan, let me know as soon as you find the other set as I will take them from you.
Brendan, let me know as soon as you find the other set as I will take them from you.
02-27-2008, 10:48 PM
#54
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Thread Starter
I finished the last couple pistons today in the nice 75 degree sunny day. I want to get this car done!
Some trimming is required on the scraper, but the bottom end is basically assembled. Next is whatever I am doing to the heads.
Nice smooth assembly on the rotating assembly. No real snags that I see.
I'll get some pics up.
Colin - I have the two additional cam cover plates. Did you want me to send them?
Some trimming is required on the scraper, but the bottom end is basically assembled. Next is whatever I am doing to the heads.
Nice smooth assembly on the rotating assembly. No real snags that I see.
I'll get some pics up.
Colin - I have the two additional cam cover plates. Did you want me to send them?
02-28-2008, 09:27 AM
#55
Rennlist Member
Larry took down the articles on his development of the Boss 429. I used to have hardcopies that were lost years ago.
I do remember Larry "fixed" the Ford castings by adding quench pads that Ford took away. There were some beautiful pictures in that article.
From his site:
1969 Constructed Ford BOSS 429 Mustang A/FX S/S Eliminator race car. Set 13 world records in two weeks in competition. Developed the first plenum ram intake manifolds for BOSS 429engines. Chassis and body used advanced materials and high stress engineering technologies.
1970 Received sponsorship from Ford for continued development of cylinder heads, pistons, manifolds, etc. for the BOSS 429 engine.
I do remember Larry "fixed" the Ford castings by adding quench pads that Ford took away. There were some beautiful pictures in that article.
From his site:
1969 Constructed Ford BOSS 429 Mustang A/FX S/S Eliminator race car. Set 13 world records in two weeks in competition. Developed the first plenum ram intake manifolds for BOSS 429engines. Chassis and body used advanced materials and high stress engineering technologies.
1970 Received sponsorship from Ford for continued development of cylinder heads, pistons, manifolds, etc. for the BOSS 429 engine.
02-28-2008, 10:03 AM
#56
Three Wheelin'
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Thanks for the info, Dan. If they were on the internet, even for a short period of time, then there must be copies somewhere. I will find them.
~~~~~~~~~~~~~~~~
OK, back on topic:
Ignore that Procharger pretty picture, it is not DATA.
~~~~~~~~~~~~~~~~
OK, back on topic:
Ignore that Procharger pretty picture, it is not DATA.
02-28-2008, 04:26 PM
#57
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03-13-2008, 12:45 AM
#58
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I am starting a new thread as an offshoot to this thread, which will stay and have more pics of the assembly.
The new offshoot thread is "Port and Polish by committee" HERE: https://rennlist.com/forums/928-forum/416667-port-and-polish-by-comiittee-thread-cool-pics-throughout.html
The new offshoot thread is "Port and Polish by committee" HERE: https://rennlist.com/forums/928-forum/416667-port-and-polish-by-comiittee-thread-cool-pics-throughout.html
03-13-2008, 01:46 AM
#59
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Brendan,
This is truly nice work. I recall doing mine and if there's one thing I would do differently, it would be to make sure I have a good seal at the base of the oil filler neck. I've aquired a metal unit since but have not gotten around to changing out the plastic one currenly in there. I hate oil leaks.....
This is truly nice work. I recall doing mine and if there's one thing I would do differently, it would be to make sure I have a good seal at the base of the oil filler neck. I've aquired a metal unit since but have not gotten around to changing out the plastic one currenly in there. I hate oil leaks.....
03-13-2008, 02:05 AM
#60
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Thread Starter
Brendan,
This is truly nice work. I recall doing mine and if there's one thing I would do differently, it would be to make sure I have a good seal at the base of the oil filler neck. I've aquired a metal unit since but have not gotten around to changing out the plastic one currenly in there. I hate oil leaks.....
This is truly nice work. I recall doing mine and if there's one thing I would do differently, it would be to make sure I have a good seal at the base of the oil filler neck. I've aquired a metal unit since but have not gotten around to changing out the plastic one currenly in there. I hate oil leaks.....
Did you use the paper seal or the rubber one that sits in the groove?