qlawson

Not sure where this was sourced from, but appears to show the output numbers:

http://www.teamzr1.com/ubbthreads/ub...=4740#Post4740

BuckyThreadkiller

465 hp, 448 ft/lbs torque.

Impressive.

LT1_E85_Corvette

It will be slightly higher than these numbers based on the video i watched today. Things are looking good!

jvp

Either that graph was scanned crooked off of a piece of paper, or it's a fake. The HP and Tq lines must cross at 5252, meaning that the LT1 and LS3 respective cross points should be on the same X point. They're not.

jas

Guibo

Looks like someone took a metric scale and implemented it close to what an American scale should look like. The scaling of one of the charts is off as the crossover point from each set of engines should still cross at the same vertical axis.

skank

Here's a good explanation why both curves cross over at 5252.
http://www.pedrosgarage.com/Site_5/Torque_vs_HP.html
An even better description.
http://www.hotrod.com/techarticles/h...e/viewall.html

larryfdx

Did you care to share? What video? Cmon cmon!!!

sam90lx

HurricaneRN

383ft/lb torque at 2000 rpm. I'd say the scale on that graph is skewed somewhere.

AmmoVet

Try this one from the bash,sorry about the angle!

CPhelps

That graph is from the SAE International paper titled:
"Development of the Combustion System for the General Motors Fifth Generation "Small Block" Engine Family" that was being discussed here:http://forums.corvetteforum.com/c7-g...hard-data.html this past April.

In the paper it is not stated if those numbers come from a computer simulation or GM testing, but the paper and graph itself has no statement of being official SAE certified numbers. If these are produced from GM testing, it is safe to assume the certified numbers will be pretty close, assuming GM testing is close to the certification requirements, which would make sense. If it is a simulated model, again, you'd assume with all the dyno time they have, they could have well vetted models that are close. Either way I do not believe this is an official certified power graph, but likely very representative of what we will end up with. It is unknown at this time why this graph shows the car running to what appears to be 7200rpm when all official specifications list the LT1 and C7 max engine speed as 6600 rpm.

I believe scale differences between HP and TQ can make it appear that the graphs are not crossing at 5252 rpm.

For what it's worth the similar graph presented of the Gen V 4.3L vs. the old 4.3L shows approximately 70kW (~94 hp) gain vs. the old 195hp, which puts it pretty close to the 285hp that the LV3 Gen V 4.3L ended up being certified at.

speed_demon24

Not when the graph goes up on different scales on each side. The cross over point will move left or right depending if the power is higher or lower than the other graph.

JoesC5

Notice that the graph posted by the OP says "high performance variant". My understanding is that a "variant" is just that, a variant from the base. it is not the base, or it wouldn't be called a "variant". From the dictionary...."one that exhibits variation from a type or norm".

This is the graph of the base LT1 from GM.


Compare the torque curve between the two graphs. Notice that the torque curve of the graph I posted backs up everything GM has been saying since last fall. The torque curve of the "variant" is completely different as it does not exhibit the high torque between 2,000 and 4000 RPM that GM has always said was as high as the LS7.

CPhelps

I think they mean the high performance variant of the Gen V, which is the LT1. That is why LT1 is in parenthesis. If they were this far along testing a high performance variant, it would have its own engine code, and LT1 would not be mentioned at all.

qlawson

It is worth noting that this graph is using metric units, Nm and kW, as opposed to Imperial units, lb·ft and hp.

The constant is 9550 for these metric units, not 5252. Also, you will notice the Nm and kW vertical axes do not scale the same in this graph, so the cross points will not occur in the standard position.

JoesC5

GM will not disclose future engine programs, thus they won't tell us what the RPO of a future engine will be (LT4 or L88 or ????). They did say it was variant while letting us know that the norm is a LT1.

It's possible that GM is looking a high performance "variant" that does not have VVT or AFM, thus the shift upward in the engine's torque and the 7000 RPM redline. Change the cam profile, dump the VVT, get rid of the AFM's eight heavy lifters and you now have an engine that will rev higher and produce more peak horsepower, but will sacrifice the low end torque that GM says is the hallmark of the LT1. This variant from the norm does not even mean it will ever see production. I'm sure GM has tested a lot of different "variant" engines while developing the GenV platform. Just because they tested a variant does not mean it will ever see production or that the "variant" will be the "norm".

When GM disclosed the specs of the LT1 last year, they showed the graph I posted. They did not show the graph that the OP posted. There must be a reason why they chose to show one graph and not the other.

CPhelps

The graph you posted is preliminary Media information with actual units and scales, the other is internal testing data that was being put into the SAE paper, not meant for the average consumer. The red lettering was added by whoever took it from the paper to make it easier to read, as it does not appear on the paper. You think in order to "not disclose future engine programs", they would withhold the name, yet publish the power graph in an SAE paper? If they were only trying to tell us that the engine was related to the LT1 engine family, their statement that it is the Gen 5 already does that.

The graph in the paper is next to the graph comparing old school sbc based 4.3L to the new Gen V LV3 4.3L.

The figure caption says "WOT performance comparison of Gen 5 6.2L high-performance variant (LT1) to its Gen 4 predecessor (LS3).

This to me means that they are comparing LT1 to LS3. They consider the LT1 to be the LS3s predecessor. The hypothetical higher output LT1 you are speaking of would not be the predecessor to the LS3, IMO. The wording and parenthesis makes it pretty clear it is the LT1. They didn't say the high-performance variant of the LT1, the way the sentence and parenthesis are used means that it is the high performance variant, and its name is LT1.

Them saying "variant" means it is a variant of the 6.2L Gen V SBC engines, the high performance one being the LT1, the other being the L86 for the trucks.

Plus the fact that 465hp is right in the ballpark that makes sense for the LT1 only helps the case. I could be wrong, but this is how I read it, and no offense but it seems to me like you're grasping here.

EDIT: Look, I'm not saying that graph IS 100% the certified numbers of the LT1, or that the stock LT1 as released in a C7 WILL be able to rev to 7200 rpm, all I'm saying is that graph is data from SOME test (either "real" or simulated software run) of the LT1 by GM. And it was the "normal/finalized" LT1 enough to be in a paper discussing the combustion system of all of the Gen V engines.

SCM_Crash

Why would you dump VVT... Especially on the high performance model?

VVT lets the engine have its cake and eat it too. No need to sacrifice torque or power to get more of the other through timing. VVT allows you to retard and advance timing throughout the RPM range to get the most torque and power through timing.

CPhelps

As far as I know, GM's pushrod VVT system doesn't require anything special as far as lifters go, so you could theoretically retain all the performance benefits of VVT without the heavier AFM lifters, and still enable your 7200 rpm redline.

Edit: I looked it up, and the L92 engine, the first OHV V8 engine to feature VVT, uses the LS7 lifters (GM eventually listed these as replacement and used them for all Gen III/IV engines). It does not have AFM, making it essentially a truck-spec LS3 with VVT. So if GM powertrain was so inclined, they could create an engine with VVT but without AFM and avoid the problematically-heavy-for-reving AFM lifters.

JoesC5

I was looking at the graph shown by the OP. You will notice that there is low torque at low RPM so that indicates, to me, the engine was not equipped with VVT. The VVT gives a very flat RPM curve at low RPM, as shown by the graph I posted, whereas that "variant" LT1 has a steep climbing torque curve.
Notice that the torque curve of the "variant" LT1 is almost identical to the torque curve of the LS3 also displayed on that same graph, and the Corvette LS3 does not have VVT.

Like you, I wouldn't think that cam phasing would limit the RPM like the AFM lifters would. I was just comparing the two graphs.