IS GM capable of making a small block DOHC

[SEVEN-OH JOE]

Truck, you're using a supercharged LSA (wet-sump) as your size comparison engine. Try, like the LT5 is, an NA LS. Shorter in height. And the width difference is from using the LS measurement WITH exhaust manifolds, and the LT5 WITHOUT. And vehicle application plays a part in which belt/drive system is utilized, affecting length.

LS blocks have the capability of displacements beyond 450 cu. in. LT5 was all done @ 415. Oil Pan dimensions play a part in these equations, too.

Here's Ford's own comparison of their V8 engines, and the ModMotor is the largest:

http://www.google.ca/imgres?imgurl=h...QEwBA&dur=1878

The ModMotor is as BIG in w-I-d-t-h as their former BOSS 429 and SOHC 427s...and that's BIG! Lots of work to put one in an early-Gen Mustang.

[Stew]

I think GM is afraid to take another crack at a DOHC V8 because of the myriad of issues and underperformance the Northstar provided. that said, there is absolutely nothing wrong with modern OHV as the advantages have been documnted well in other parts of this thread.

[72MachOne99GT]

Technology is awesome, but clearly spoils people.

A stock LT1 in the f bodies in 93 was a super impressive shot to the dick of Fords Mustang.
now there are heavier, 6cylinder family sedans that are nearly as quick as they were while getting better mileage, increased reliability, and we arguing about torque.

1st world problems

[DGthe3]

Originally Posted by fielderLS3

You make plenty of very good points. But the point still remains that in the last several decades, engines have indeed gained a lot of power, they have not gained that much torque. The net result is any horsepower number that is advertised has to be taken with a grain of salt, because something similar with what happens to currency through inflation is happening to horsepower ratings.

Basically, today's 300 hp engines aren't as strong as a 300 hp engine from 10 years ago was. I'm not saying today's DOHC engines are necessarily weak in absolute terms, but 300hp and 325tq is simply not the same as 300hp and 275tq. Run a 5th gen V6 against a "less powerful" 05-10 4.6L Mustang and see what happens. Or, alternatively, ask yourself what you would rather have, the 5th gen's V6, or the 4th gen's LS1?

You own an Alero, which makes up to about 200 ft-lbs of torque (unless you've got a 4 cylinder) from a 3.4L engine -same as my Grand Am, and we can now get V6s slightly larger with 1/3 more torque. How is that not a big improvement in a decade? The V6 in the Camaro makes almost twice as much torque as its counterpart from 30 years ago. Has torque progressed as quickly as power? No, because its easier to make more power than it is to make more torque. But that doesn't mean there haven't been big improvements made.

Is a big older V8 more stout than a modern medium sized V6? Sure. But that doesn't mean that these V6s are 'weak'. Its like saying that a pro-athlete is weak because they're not a powerlifter. No, they're still plenty strong -just not freakishly strong.

[GretchenGotGrowl]

Originally Posted by demonspeed

*disclaimer* I'm sure you're stating this in the context of power. I'm sure there are plenty of reasons -- drivetrain aside -- that V6 Camaro owners would choose the 5th over the 4th.

With that said, I like that there are some fools who think their "more powerful" 5th gen V6 can whoop on those "crappy" LS1 Camaros



Another aspect that gets overlooked is gearing. One could build a weak engine but put it in front of an optimally built (ratio-wise) transmission/axle.

Gearing and weight are factors when comparing the 5th Gen V6 to the LS1 V8s as well.

[demonspeed]

Originally Posted by GretchenGotGrowl

Gearing and weight are factors when comparing the 5th Gen V6 to the LS1 V8s as well.

It'd be interesting to see a LFX swapped in to a 4th gen just to see how things would work out.

However, my comment about the LS1 takes into account more than weight and gearing -- that the LS1 in the Camaro only made 305-325hp on paper... but it's a fact that it was just the same as the Corvette/GTO LS1 @ ~350hp.

[GretchenGotGrowl]

Originally Posted by demonspeed

It'd be interesting to see a LFX swapped in to a 4th gen just to see how things would work out.

However, my comment about the LS1 takes into account more than weight and gearing -- that the LS1 in the Camaro only made 305-325hp on paper... but it's a fact that it was just the same as the Corvette/GTO LS1 @ ~350hp.

Oh, I agree. The LS1 was probably underrated. I'm just saying I think the race would be close if the 5th gen V6 weighed the same and had a 3.45-3.55 rearend. They have a nice wide power band.

[Truck Norris]

Originally Posted by GretchenGotGrowl

Oh, I agree. The LS1 was probably underrated. I'm just saying I think the race would be close if the 5th gen V6 weighed the same, had the same wtq and had a 3.45-3.55 rearend. They have a nice wide power band.

Fixed it for ya.

Originally Posted by SEVEN-OH JOE

Truck, you're using a supercharged LSA (wet-sump) as your size comparison engine. Try, like the LT5 is, an NA LS. Shorter in height. And the width difference is from using the LS measurement WITH exhaust manifolds, and the LT5 WITHOUT. And vehicle application plays a part in which belt/drive system is utilized, affecting length.

I only used the LSA as an example because you brought it up. Here is a demential pic of a NA LS without manifolds to compare to the LT5. To me it looks like the DOHC LT-5 is a whopping inch and a quarter wider and the same in height and length then this NA LS. I'm just trying to point out that not all DOHC mills are as wide as a Ford's modular design. If GM wanted to they could build DOHC engines that will fit just fine in everything that currently has an LS and still be a popular swap engine for custom builds. It would also most likely not have AFM/DOD and Gas Guzzler tax.

[demonspeed]

Originally Posted by GretchenGotGrowl

Oh, I agree. The LS1 was probably underrated. I'm just saying I think the race would be close if the 5th gen V6 weighed the same and had a 3.45-3.55 rearend. They have a nice wide power band.

I don't want to go too off topic, but since this is mentioned, I figured to just bust out the specs so people can infer on their own.

2012 LFX 323hp/278tq
2002 LS1 350hp/365tq

I don't think the weight difference would help all that much considering the 27hp/87tq deficit.

[GretchenGotGrowl]

Originally Posted by demonspeed

I don't want to go too off topic, but since this is mentioned, I figured to just bust out the specs so people can infer on their own.

2012 LFX 323hp/278tq
2002 LS1 350hp/365tq

I don't think the weight difference would help all that much considering the 27hp/87tq deficit.

Not saying the LFX would win. However, look at the torque curve of the LFX. It makes 250 tq from way down low to almost red line. The LS1 one kill it off the line, but after that the LFX will be near peak power the rest of the way down the track with the right gearing. Lower the weight to that of a 4th gen and the LFX with the right gears is a 13.5-13.7s car easy.

[SEVEN-OH JOE]

Originally Posted by Truck Norris

I only used the LSA as an example because you brought it up.

Really? where?? ONLY against the Ford 5.8. Which shares the dimensions of the Ford GT's 5.4. Which I also included. And the 5.4/5.8 is a BEHEMOTH!


Here is a [dimensional] pic of a NA LS without manifolds to compare to the LT5. To me it looks like the DOHC LT-5 is a whopping inch and a quarter wider and the same in height and length then this NA LS.

To YOU, only, because you're GUESSING at the LT5 dimensions for an engine conceived with displacement limitations and, therefore, a smaller block. My original assertion.


I'm just trying to point out that not all DOHC mills are as wide as a Ford's modular design.

True. But what better example to show the OP that Ford's own examples. DOHC V8 engines can work in engine bays where size is not a prerequisite, aka F-Series, but they run into physical limitations where packaging IS a necessity, aka S550.

If GM wanted to they could build DOHC engines that will fit just fine in everything that currently has an LS and still be a popular swap engine for custom builds.

But that's NOT the future path of things, is it? "Smaller-Lighter" is written all over Advanced Vehicle projects, and GM has already learned from Ford's mistake, above.

It would also most likely not have AFM/DOD and Gas Guzzler tax.

You're back to guessing again.

One thing IS "for sure and certain": GM's LS-Series V8s have proven to be less expensive to manufacture, long-lasting/durable, and adaptable to modern technologies (AFM/DOD). Who'da thunk, even 20 years ago that the then-new 300 hp (in a Vette) LT1 could evolve into a 638 hp daily driver-capable Vette with 25 mpg capabilities, within an environment of ever-tightening emissions and CAFE requirements?

And the next-Gen LT family only promises more for le$$.

[Stew]

Originally Posted by SEVEN-OH JOE

One thing IS "for sure and certain": GM's LS-Series V8s have proven to be less expensive to manufacture, long-lasting/durable, and adaptable to modern technologies (AFM/DOD). Who'da thunk, even 20 years ago that the then-new 300 hp (in a Vette) LT1 could evolve into a 638 hp daily driver-capable Vette with 25 mpg capabilities, within an environment of ever-tightening emissions and CAFE requirements?

And the next-Gen LT family only promises more for le$$.

to be the yin to your yang, who would have thought the 190 HP V8 powering a 92 Town Car would evolve into the 662 HP monster powering the most powerful production Mustang ever.

Edit: Actually the LT1 in the 92 Vette isn't really related to the LS series engines, so the LS9 would actually trace it's roots back to the origional 346ci LS1 that appeared in the Vette in 97.

[SEVEN-OH JOE]

Wow! You're right, of course, as the Town Car was certainly a beacon of performance for Ford in '92, Stew.

EDIT:

The new-for-'92 LT1 "reverse cool" SBC, rated @ 300 hp in the Vette, was "state of the art" for OHV architecture and was considered a heck of a step forward at that time. More power, better mpg, and cleaner emissions through cylinder head technology and more consistent cooling. Future developments would lead to even more impressive results. By the way, all SBC engines, since the '55 Model Year 265 cu. in. V8 through the newly-arrived LT-family, share a common bore spacing, thus maintaining a "familial" relationship.

Ford countered with their DOHC V8 that they offered in their best production version of luxury and performance in '93, the Lincoln Mark VIII, and was rated at 280 hp. Impressive from only 4.6L. But BIG and heavy in physical size/weight, a recurring issue when packaged in smaller vehicles such as the Mustang, post-'94.

Source: SAE

[demonspeed]

Originally Posted by GretchenGotGrowl

Not saying the LFX would win. However, look at the torque curve of the LFX. It makes 250 tq from way down low to almost red line. The LS1 one kill it off the line, but after that the LFX will be near peak power the rest of the way down the track with the right gearing. Lower the weight to that of a 4th gen and the LFX with the right gears is a 13.5-13.7s car easy.

Do you have a link to a LFX curve? I tried searching but can't find one.

Here's a LS1 curve: http://www.geareddrives.com/LS-1%20HP%20vs%20Torque.jpg

That's great that the LFX makes 250tq at lower rpm, but the LS1 belts out 325tq at 1800.

Now, when we introduce E/T's, do we also want to consider trap speed? If so, you're going to see several mph lower with the LFX simply due to the lower power.

As an FYI, I'm not trying to infer the LFX is an inferior engine. I'm only speaking in the context of racing against a LS1 in equally-bodied vehicles.