A couple of pictures from the Detroit Auto Show of the 2014 Corvette.
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A couple of pictures from the Detroit Auto Show of the 2014 Corvette.
The third LT1 engine...
Yeah, what's up with that ? I mean the first time they re-used the engine designation it was kind of cool. They resurrected the name of a pretty potent small block that was actually the last decent small block used in the corvette for 20 years. The 20 hp increase in power with the addition of direct of injection is kind of a let down, but I'll bet that within a year or two another even more potent base engine will pop up. They tend to do that to keep interest up. I am still undecided on the looks, but the performance is improved again.Quote:
Originally Posted by EagleMark
Stingray is back as well! Now with Direct Injection!
Do I detect a hint of sarcasm there ? :laugh:Quote:
Originally Posted by EagleMark
The direct injection stuff is pretty cool honestly though. But if they wanna revive the stingray again they should try to add at least some styling cues from the stingray. That's what I'm not real fond of with the looks. It looks like they ran out of ideas once they got to the tail and pasted the ass end of a camaro on there or something. It just doesn't mesh with the rest of the car if you ask me. But I'd still sell my left nut to have a new vette. I mean at the end of the day they are still an impressive machine and they outperform anything else in that price range.
At the Detroit car show they had a good cut-away of the new engine. Unfortunately we forgot to get a close up picture of the combustion chamber. The pistons are domed to work specific with the direct injection. Some pictures I saw of the new engine had O2 on each cylinder but they are not using dedicated cylinder o2 for production. With DI some engines are injecting fuel during exhaust stroke to increase cat and o2 warm up times.
I have a bunch of pics of the internals of a direct injected 3.6 that I haven't gotten around to uploading and adding notes to. When I finally get around to it I was planning on starting a thread for those interested in learning a little more about direct injection and whatnot. So, keep an eye out if you're interested.Quote:
Originally Posted by POZE
Seeing the pictures would be great.
I misspoke on the other post. The goal of injecting at the end of power into exhaust stroke is to decrease cat and o2 warm up time.
I can't really visualize much and grasp a concept based on a verbal/written explanation when it comes to anything. But if I can see pictures and illustrations of how something works I usually don't have much trouble learning and understanding how it works. Direct injection is fairly simple mechanically speaking, but it is still pretty cool to see pics. I don't remember much in the way of emissions related stuff when I did my training on GM's direct injection stuff so I wouldn't recall any strategies like what you mentioned but it makes sense. All that I really paid attention to and committed to memory was information relating to driveability and mechanical failure diagnosis and repair.Quote:
Originally Posted by POZE
They are basicly copying diesels...lol. If you know how a common rail diesel works, or even just a regular diesel works, then the direct injection is more or less basicly the same. Very high pressure fuel injected directly into the cylinder instead of the intake.
I watched the unveiling for this, live.
This is the first 'Vette, since the '63, that I like the looks of.
Very Ferrari influenced.
The lack of new name for the engine is not only a let down, but annoying at the same time.
Now when someone says "I have an LT1", you have to ask if it's the 1st, 2nd or 3rd iteration. :facepalm:
You're right, they are basically a copy of a diesel and the fuel systems operate in the same manner. I am totally clueless as to the design and development of direct injected engines by other manufacturers so I don't know what their engines look like inside. When GM first started using SIDI engines in a few of their vehicles I was pretty curious to see what everything looked like. I know from conversations with a field engineer that GM encountered some unique problems while developing their SIDI engines. As a result the pistons have a unique design on top. It is also intriguing to see how they modified the engines to utilize direct injection since they are all based on existing designs. All of the engines up to the "new" LT1 were adapted without any cylinder block modifications or any "major" modifications. Some small changes to the cylinder heads and new pistons were all they had to do to facilitate the adaptation. Sadly it appears that I have finally been locked out of GM's system now and I myself am a little curious to see the cylinder heads on the "new" LT1 as well as the pistons so I'll have to pull a few strings to get back in the system.Quote:
Originally Posted by JeepsAndGuns
Some of the things I've read about direct injection opens new doors to Lean cruise! Piston is already half compressed before fuel is injected and ignites with a barrier to piston and cylinder wall. No heat! 21.x AFR...
Almost like a combustion chamber in the piston. Like diesel.
A fair share of the direct injection engines that i saw cutaways of,have oil spray nozzles pointed to the bottom of the pistons.
Yes, lean cruise can be taken pretty far because the injector timing can be altered which greatly reduces the risk of detonation. The pistons that I have seen do have a strategically located and shaped recess that serves as a mini combustion chamber. It is very similar in concept to the pre-combustion chambers used in some diesels. These features also allow for even higher compression ratios without the increased tendency to detonate. I am also wanting to think that piston squirters were a feature on the 3.6 high-feature v6 and it's other variants. I'll see if I can verify that info later. Anyway, I do have a "teaser" pic that I can share that is a pic of a direct injected v6. If you look real closely you can see a couple witness marks on the outer edges of the dome (yeah that's right I said dome) from the intake valves making contact. This thing saw 20k mile intervals on regular old conventional oil because that's what the oil life monitor said and believe it or not GM says that's perfectly fine. This is the result of going by the "approved" maintenance schedule which was new cylinder heads and timing chains all before 100k miles. :doh:
Attachment 3711
No, just one regular combustion chamber. EDIT: Well maybe there was piston chamber stuff not mentioned?
Well the oil spray would help keep the piston cool, most get cooled by oil from wrist pin anyway, piston is what get's hot in lean cruise! But oil could still get hot after awhile.
The theory I described was more physics, the Air/Fuel mixture was cool entering a hot combustion area, never touches piston or cylinder walls, explodes mid air, like a barrier. There was also some mention of double fire, one during compression and one at or just after TDC...... wish I could find the article......... wish I could find the article...
Here is a pic of the rear that I lifted from Chevy's website. I just can't make myself like it. The rest of the car is slick but the back end is a disappointment to me still.
Attachment 3712
I'm still patial to square body Chevy trucks... but I still think it's sweet looking...
What I meant about the impression being like a mini combustion chamber actually has to do with getting the fuel mix to light off and burn properly. That was one of the problems that GM ran into during development. It evidently took a lot of trial and error to get the size, shape, depth, and location of the little "trough" on the piston just right. EDIT: After re-reading my reply I see that I sort of mixed different points all together by accident. The features that allow for more compression are direct injection and injector timing. I apologize for the confusing jumble there.
Since the piston squirter question was eating at me until I could confirm it and I'm now locked out of GM's system I googled the high feature v6. I don't think I can go a few hours without google sometimes lol. Anyway, it led me to a wikipedia page that after reading appears to be pretty accurate. There are a couple of small details that I'm a little unsure about like I've never seen one with vvt on the exhaust only, but overall it's dead on with the major facts. I'm gonna add a link below just because you can see the increased compression ratios and power output of the direct injected versions. The piston squirters are mentioned as a capability, but I'm still thinking that all of the north american versions were equipped or at the very least the direct injected ones are.
http://en.wikipedia.org/wiki/GM_High_Feature_engine
I thought the LS engine (or atleast some of them) already had those? It seems I remember seeing a buildup of one somewhere (either on tv or online) and I remember the oil squirters and thought it was interesting.Quote:
Originally Posted by POZE
On the LS platforms the only engines that have piston squirters are the LSA & LS9. From what I understand all GenIV blocks have a boss that can be machined for the squirters as well as the LSX blocks.Quote:
Originally Posted by JeepsAndGuns
oil squirters are to keep the pistons cool. leave a squirter out of a 3406 cat engine and you can kiss it goodbye after a short time. ls9 is supercharged with higher compression in which the piston would benefit from having squirters. the precombustion chambers are bfor mixture of fuel and to keep it centralized to not spread it that would just cause a hot burn. direct injection is in most diesels and work great. its about darn time someone put it together in a new performance gm.
The use of piston squirters in direct injected engines is to cool the pistons because of the lean mixtures used under certain conditions. I don't remember the reason, but I believe that oil squirters have been in use on the high feature V6 prior to the direct injected models. I was also thinking that the LS7 had squirters, but have not been able to verify that yet. Something that was quite a rarity was having to perform any kind of repairs on the bottom end of the high feature V6 engines or the LS7. GM has been a little slow to adopt "newer" technologies to any of it's performance engines. They have been making flex-fuel vehicles for years now, but still they don't offer the capability on the corvettes and camaros.
Thank God!Quote:
Originally Posted by pmkls1
The "High Feature V6", the 3500 used a single piston squirter for the 5 and 6 cylinders. It looks like the squirters can be added to the other 4 cylinders and is why I have some just for that very reason. ;)
I know that you aren't a big fan ethanol Mark, but you do realize that in an engine like the LS3, LS7, LSA, LS9 or the "new" LT1 running E85 would help to coax a few more ponies out of them ? A perfect example of how E85 can improve a sports car's performance would be the Koenigsegg CCXR. It is a flex-fuel capable supercar and quite a monster making a stout 806hp on gas, but puts out a whopping 1018hp on E85. That is a massive 212hp increase just by filling up at a different pump. Granted the CCXR is twin turbocharged, but higher performance N/A engines do make more power with E85 too. Most of the issues that plague E10 aren't a concern with E85 and corrosion isn't a concern because these vehicles are designed to be compatible with alcohol. Since there is 70-85% alcohol it would take a boatload of water to ruin the fuel and I don't think that phase separation is a problem due to the small amount of gas and/or other chemicals that make up the remaining 15-30% of the fuel.
The 3500 V6 is in the high-value V6 line. The high-value V6 line is just the latest version of the long-lived 60 degree V6 platform that debuted in the '80's. With the exception of the twin-cam 3.4 used in W-bodies in the '90's all of the other versions were a typical pushrod layout with 12 valves. There was of course the twin-cam 3500 V6 that was only around for a couple years that was based on the Northstar, but they are pretty rare. The high-feature V6 debuted in 2004 in the Cadillac CTS, and while it is also a 60 degree engine it shares nothing with the old chevy 60 degree V6. The high-feature V6 is an all aluminum 24 valve double overhead cam design with variable valve timing. The most common displacement is 3.6 liters, but there are 2.8, 3.0, 3.2 versions out there. The piston pictured above in one of my posts is a direct injected 3.6 piston. Direct injection was also something that never made it to the high-value line.Quote:
Originally Posted by Six_Shooter
Dream car! *drool*Quote:
Originally Posted by pmkls1
It's not that I am against ethanol, E85 and cars designed for it show great results... if you can push enough fuel through you can obiviously make more power with more octane. But it still get's less MPG...
My issue with E10 is it was forced on us while the majority of vehicles were only marginally capible of using it without damage or running lean. Fuel milage also suffered, cost didn't go down for us/end user but our milage did while oil companies reaped benifits of goverment reductions of taxs etc... but the real issue was corrosion damage to even older vehicles, rotten wasted lawn equiptment etc...
I totally agree with your opinions about E10 and the inevitable E15. I have been suspicious that some of the negative effects have been played up a little by some in the auto repair industry and also in the chemical additive industry for the purpose of profit though. The reduction in MPG when using E85 COULD and SHOULD be offset by lower cost, but the cost stays inflated due to a few factors. The largest factor for inflation is the simple fact that only certain gas stations have spent the money to install new pumps and tanks for it and they can jack up the price because they don't have any competition. I have decided that as long as things stay on track my house will be paid for in 4 years and I am going to build my own distillery in the back yard and make my own fuel.Quote:
Originally Posted by EagleMark
I still have yet to see any real damage from E10.
My grandfather owns a 1940 Dodge, that he restored back in 1990 or 1991, the fuel system is all original, or at least original type replacement parts, the engine is a 1950 model IIRC, and has NEVER been opened, it runs like a top. No signs of gumming, corrosion or any other issues. Along with multitudes of other vehicles I have owned, worked on, serviced, and rebuilt. Never one sign of damage that could be caused by fuel, not one.
I do agree that milage sucks, though I can't completely blame the fuel for that one, I do have a heavy foot.
Canada may have better fuel ey?
http://www.fuel-testers.com/list_e10_engine_damage.html
NONE of those problems are E10 specific.Quote:
Originally Posted by EagleMark
All that list does is list possible engine problems, that could happen to any engine running any fuel. The only E10 "specific" items in that list are based on possible stored energy.
Ethanol specific... or alcohol, how ever you phrase it...
Never seen or heard of the engine problems, but I sure have dealt with the moisture, corrosion and seperation.
You run E fuel in your lawn mower? Stored over winter? Hows it run in the spring? Take a galss jar and put E fuel in it and leave it open, see what happens the next day. Have to do this above 32 degrees so there's moisture in the air. Seriously, I'd like to know why you have no issues and if your fuel is differant?
This spring I am going to the dump everyday and pickup all last years brand new lawn mowers and fix them for sale. Rich people just buy new ones when they don't start in spring here...
I have seen the demonstrations that illustrate the moisture issues and phase separation so I know that it isn't just a myth. I have had vehicles come in for repairs that had cloudy fuel, but the incidents were too isolated to be able to determine a definite cause. I have also had to drain fuel tanks due to bad fuel, but in those cases they had been stored for very long periods of time so again the true cause couldn't be identified. I also store my lawnmowers in the basement over the winter every year and haven't encountered any problems honestly. The only problems that I have personally encountered that could be positively identified as ethanol specific were cases where the ethanol content was over 10% causing the fuel trims to go over the threshold and set lean codes. My experiences coupled together with the knowledge that the underground tanks at gas stations do get contaminated are the reasons that I am a little skeptical of just how much damage is actually due to ethanol. That is why I said that I don't dispute the fact that E10 causes problems I just feel like it is played up a little by certain people. Still, a true standard needs to be established with gas across the entire country and all gas engines manufactured for the U.S. market need to be designed to operate properly on said standardized fuel.