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Replying to Predictions for NEW 2.0T engine


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Posted 20 January 2012 - 04:56 PM

Dwight the compression hight can be changed by the rod or piston but is normaly altered by the piston it self. In looking into the cheapest way to build a mega mouse SB Chevy I found that in using a off the shelf piston designed for a 5.850 length rod instead of a 5.7 the piston would be at deck hight with my custom stroke

And now you guys will see how bad I spell with out spell check. I've updated my Linux distribution and now as Hyper says I can't get spell check to work within the fourm outside it OK but not here. Any ideas? I'm using FoxFire maybe I'll D/L Chrome or try KDE's default. I hate looking dumb since I at least know that its spelled wrong if I see it. It's not that I'm lazy I'm dixlexic plus spelling was my worst subject I can spot incorrect spelling though and that just makes it so much worse.

Posted 20 January 2012 - 04:47 PM

That was the point I think hyper brought up, wouldn't the 2.5 pistons start smacking off the valves?


Why will they? The 2.5 pistons are 88 mm wide vs 86mm wide for the 2.0. Mainly the reduction in bore in the 2.0 is to give it thcker cylinder walls.

If you bore a 2.0 out to 88mm and simply use the 2.5 pistons, the pistons are not going to travel higher or lower than in the 2.0 engiine.

If the two engines have the same deck height relative to the crank axis, it means that the 2.5 has long crank throws with shorter connecting rods, whereas the 2.0 has shorter crank throws with longer connecting rods.

Posted 20 January 2012 - 12:29 PM

That was the point I think hyper brought up, wouldn't the 2.5 pistons start smacking off the valves?

Posted 20 January 2012 - 12:28 PM

The press release says "The 2.0T has a wide torque curve, delivering 90 percent of its peak 260 lb-ft. of torque (353 Nm) from 1,500 rpm to 5,800 rpm"

Doesn't that mean it has at least 260 lb-ft at 1,500 rpm?


GM's official site now reports 270 hp @ 5300 & 260 lb-ft @ 2400. So that settles the doubts as to when the actual peak arrives, despite 90% of it being available from 1500 to 5800 rpm.

http://media.gm.com/...08_ats_overview

Posted 20 January 2012 - 12:19 PM

Wouldn't the rods have to be longer to make up for the stroke loss from the 2.0 crank? I may be picturing this wrong, but a shorter stroke crank with the same height pistons and same length crank would end up lowering compression? The space left in the cylinder when the piston is at TDC would be 7.5mm greater, no?


No, the stroke will not need to be longer. Combining the 2.5 pistons with the 2.0 crank gives you 2.14 liters of displacement. The crank determines the stroke length -- how much the pistons are moved. What needs to be longer is the connecting rods if you want to maintain the compression ratio (or increase it). Otherwise the pistons simply wouldn't go as high and the compression will be lower -- displacement doesn't change. Longer rods, although slightly heavier, can actually be good for high rpm durability because they reduce the side loads on the cylinder walls. When the crank pin is at 90 or 270 degrees, the longer the rod the narrower the rod angle and hence side thrust loads.

Posted 26 December 2011 - 08:43 PM

I agree with Hyper. I doubt they would go backwards from what they already had.


Just on marketing alone it would be a difficult to sell a new and improved engine with less power and Torque. Even a marginal improvment would give them some brag rights.

I also expect Ford to pump more power out of the Ecoboost soon. They also have not even started to tap into what it could do.

The fact is the Ecotec is the new Small Block for the auto line up. It will be the economy engine like a 307 but it will also be the performance engine for many models like the LT1 was. The engine will be like the small block and share a design but they will come with many different internals to deal with the power they will produce.

The V6 will be the Big Block and provide the option for more of everything in the other cars. The V8 I see limited to the Corvette, Cadillac and trucks. The Camaro will keep it I feel for the next gen only in the top model but I feel it may have a limited life in the future to models like the ZL1. Ford is already to push more Eco Turbo V6 and 4 cylinder Mustangs and I suspect the V8 will also become much more limited to things like a Shelby only. That is down the road but I could see it happening by 2020 at least in the Ford.

And don't say it will not and could not work. Who ever suspected people would ever buy 100,000 F 150's with a Turbo V6 in one year at a higher price than a V8. The market and buyers are and have been shifting to new ideas of what they will buy. Higher MPG claims or not they sold a hell of a lot of trucks at a mark up and it should not go un noticed by GM.

Posted 26 December 2011 - 09:56 AM

I agree with Hyper. I doubt they would go backwards from what they already had.

Posted 26 December 2011 - 09:52 AM

We can come up with a lot of specuations and toss around a lot of numbers but what was GM looking at?

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This is where GM was looking when the money dried up. I suspect that things have not changed a lot and that the new money will be producing engines very similar in power and torque. I'm not saying this is the new engine but we can see what kind of numbers GM was working on and it should give us an idea where they were wanting to be by 2010 and later if they had not had to put many things on hold.

I do think GM should change the name Torque Curve and make it a Torque Plain. Note too the cars listed all had transmissions that would be up to task on giving more torque other than the 5 speed Kappa. That may have limited them on this version of the Eco. Today we have stronger drivelines now and coming that will take more. Note the Solstice with the LNF Turbo upgrade was given 340 FT-LBs if it has the 5 speed. This kind of Torque in a ATS would feel very welcome.

Posted 25 December 2011 - 09:52 PM

Either or would need be longer that is what I was trying to convey to Dwight
I've worked up home brewed strokers before

Posted 25 December 2011 - 11:33 AM

Wouldn't the rods have to be longer to make up for the stroke loss from the 2.0 crank? I may be picturing this wrong, but a shorter stroke crank with the same height pistons and same length crank would end up lowering compression? The space left in the cylinder when the piston is at TDC would be 7.5mm greater, no?

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