LQ4 Power

[lionelhutz]

I guess everyone who is swapping an LS engine into their rides to go faster is doing it wrong...

The torque curve tells you how fast you accelerate when you have the drivetrain but the HP curve tells you how fast you could accelerate when you are picking the drivetrain. I guess if you insist on running a LS engine with a drivetrain optimized for a low HP low rpm small-block then you wouldn't see the gains the LS engine can give you.

I've really only seen curves where an older small-block had more torque below about 2500rpm but really fell off above 5k rpm where a similar LS engine held the torque until well over 6k rpm. Around 2.5-5k the torque curves are similar. I would attribute the difference to shorter intake and/or exhaust runners used on the LS engines. The LS engine is simply built to produce it's power at a higher rpm. If you insist on running <2.5k towing then the small-block could have an advantage. But, gear the LS vehicle to hold another 1000rpm or so at the same road speed and it would kill the small-block. You could also put a long runner intake and headers on the LS and it would likely match the small block power curve.

My parents take a trailer to Florida every year and their '06 5.3L LS truck used about a 1/3 less fuel than their old '90 TBI truck and pulls better too.

I'd put this LQ4 into my car over any small-block I've managed to build.

[Fast355]

I guess everyone who is swapping an LS engine into their rides to go faster is doing it wrong...

The torque curve tells you how fast you accelerate when you have the drivetrain but the HP curve tells you how fast you could accelerate when you are picking the drivetrain.

I've really only seen curves where an older small-block had more torque below 2500rpm but really fell off above 5k rpm where a similar LS engine held the torque until well over 6k rpm. Around 2.5-5k the torque curves are similar if not having the LS engine ahead a bit. I would attribute the difference to shorter intake and/or exhaust runners used on the LS engines. If you insist on running <2.5k towing then the small-block could have an advantage. But, gear the LS vehicle to hold another 1000rpm at the same speed and it would kill the small-block at all speeds. You could also put a long runner intake and headers on the LS and it would likely match the small block power curve.

My parents take a trailer to Florida every year and their '06 5.3L LS truck used about a 1/3 less fuel than their old '90 TBI truck and pulls better too.

I'd put this LQ4 into my car over any small-block I've managed to build.

The crossover point is higher up around 4,500 rpm. The reason for the elevated peak is port size and velocity. The LS head ports are HUGE compared to the older stuff. I have older Car Craft magazines with the 5.3 and the 330 hp 350 crate engine dyno's as well as a LS1 5.7 dyno. The stock crate engine cammed 350 made 377 hp and the LS1 made 400. With the hotcam the L31 + Hotcam made more power EVERYWHERE than the stock LS1 + Headers.

[Fast355]

My 350 outguns this 6.0L everywhere under 5,000 rpm and if you count the fact it is just a stock vortec 5.7 shortblock with a cam, a good pair of aluminum heads, a relatively cheap marine intake, and a pair of thorley headers and a quiet exhaust it would be under $3000 to put the parts on a solid 5.7 shortblock.

I tow up to 8,500# behind my 6,200# Express van with a 4L80E and 3.73s. I run about 2,800 @ 65 mph in 3rd and knock on 12-14 mpg with that weight. Cruising empty I am 2,250 @ 70 and 2,800 @ 85 and get 17-19 mpg. If I had a 6.0L turning another 1,000 rpm, I would have the power but my MPG would be atrocious! Under WOT acceleration with Tow/Haul on, I shift at 4,900-5,000 rpm and lock the converter at 60-65 mph. The engine pulls strong, is pretty quiet and moves the weight just fine. I looked down one day with nearly 7,500# behind me and was running 80 mph with traffic uphill with ease.

[lionelhutz]

My 350 outguns this 6.0L everywhere under 5,000 rpm....

Towing 8500lbs behind a full size van and getting 13mpg while running 2800rpm @ 65mph? I find that hard to believe. A "cheap" 350 built for towing that can make over 425ft-lbs of torque at 3k rpm and over 460 ft-lbs of torque at 4.5k rpm? I find that ridiculously hard to believe.

[Fast355]

Towing 8500lbs behind a full size van and getting 13mpg while running 2800rpm @ 65mph? I find that hard to believe. A "cheap" 350 built for towing that can make over 425ft-lbs of torque at 3k rpm and over 460 ft-lbs of torque at 4.5k rpm? I find that ridiculously hard to believe.

I put down 370 RWHP on a Mustang dyno through a 4L80E and GM 9.5" 14-bolt. I put down 340 RWTQ at only 3,000 rpm with a locked converter and peaked about 370 RWTQ at 4,500 rpm. At only 2,400 rpm it was already putting down 330 RWTQ. A 355 TPI engine with production vortecs and a 210/220 cam put down 490 ft/lbs at peak and over 400 from 2,600 and beyond.

As for the MPG, thats what it gets towing on flat land with no winds and I have pulled down 18+ running empty Do not run EGR either.

Its a stock 1-ton GM crate 350 shortblock
Edelbrock Etec 170cc heads
271/276 @.006, 215/220 @ .050, .534/.547" lift, 114* LSA Comp cam installed at 110* ICL. Crane Gold 1.6:1 SA roller rockers
Ported L31 Marine intake with an 85mm LS1 TB and 85mm maf into a stock Express airbox
0411 PCM running HP Tuners MAF Enhanced operating system
Doug Thorley Tri-y headers into 3" Thorley headpipes, reduced to 2.75" mandrel bent piping into 2.5" Thunderbolt cats and a dual in/single out Walker Dynomax bus muffler with a 3" mandrel bent tail pipe
454 radiator with factory oil cooler, duramax fan on a trailblazer ss fan clutch, Napa 200a AD-244 alternator, Racetronix fuel pump hotwire, March 4490 Underdrive pulleys. Runs a 4L80E with a B82 factory high stall converter and a 3.73 geared 9.5" 14-bolt out of a 6-lug 2500 Express.

[Roadknee]

A 355 TPI engine with production vortecs and a 210/220 cam put down 490 ft/lbs at peak and over 400 from 2,600 and beyond.

Your results again are very impressive. Regardless of the combination of parts, a 355 making 490 ft/lbs at the flywheel will require volumetric efficiency approaching 120 percent. And you accomplished that with production heads and a small street cam. Professionals building state of the art race engines strive to achieve results like these. Great work indeed!

[Fast355]

Your results again are very impressive. Regardless of the combination of parts, a 355 making 490 ft/lbs at the flywheel will require volumetric efficiency approaching 120 percent. And you accomplished that with production heads and a small street cam. Professionals building state of the art race engines strive to achieve results like these. Great work indeed!

That one was not mine, check out Something New Something Old by GM High Tech. I had a very similarly built 383 TPI in my 1983 G20 that put down 430 RWTQ.

[lionelhutz]

Yes, that's making unbelievable power for sure. It took Super Chevy 28 build combinations in their danger mouse series to come up with very similar power as this LS engine and it required 40 thou more lift and 20 degrees more duration in their cam choice compared to yours. But, they also did it with the E-tec 170 heads which definitely are a really good head choice. Their torque started dropping like a rock below 3k rpm and was below 350 ft-lbs at the crank by 2600 rpm. If their torque continued to drop like the graph was showing then their engine certainly wouldn't be any better in the low end compared to the LS engine in this thread.

So, it's really impressive you came up with a combo that makes what, another 60-80 ft-lbs at 2400rpmthan SC managed and also beats their build all the way to 5k all while using a more tow friendly smaller cam.

In other words, your engine outgunning this LS engine all the way to 5k is still rather unbelievable.Your smaller cam should help the torque below 3k rpm but no way are you beating this LS engines torque all the way to 5k rpm.

http://www.superchevy.com/how-to/pro...block-part-28/

As for the TPI engine - full block work align honed, decked etc lighter pistons with 6" rods, ported heads, ported intake, ported runners, larger throttle body. Someone who knew what they were doing worked over the heads to get the flow numbers they got. You casually write the numbers as if it was a off the shelf Vortec and TPI build, but it was really an all-out build with very few expenses spared.