Fast355

So its not exactly a LT based engine, but I figured I would post here since my engine is more LT like than anything else. Its a Gen1E L31 5.7 Vortec in a 97 G1500 Express van. Currently putting down 374 RWHP @ 5,800 and 368 RWTQ @ 4,900 through a 4L85E and 9.5" corporate 14 bolt. Currently its a stock GM Goodwrench crate engine for an 8800+ GVW has the stock 5.7 shortblock with 4 bolt mains, forged crank, 5.7" powdered metal rods, 12cc dished cast pistons, high volume/pressure oil pump, and a single roller chain. On that base I have a set of out of the box Edelbrock ETec 170cc aluminum heads. Feeding the heads I have a 3.5" OD intake setup, an 85mm GM MAF, and an 84mm single throttle body on a GM Marine L31 intake manifold with 29 lb/hr external injectors. A set of crane narrow body self aligning 1.6:1 full roller rockers, LS7 lifters and a Comp ground cam measuring 271/276 @ .006, 215/220 @ .050, .534/.547 (w 1.6:1), 114* LSA cam installed on a 110* ICL that sounds near stock @ 750 rpm idle. Doug Thorley Tri-Y school bus headers for the G-series cutaway chassis feeding dual 2.5" thunderbolt 200 cell metallic core cats into a dual 2.5" single 3" out 24" case wide body magnaflow and a single 3" tailpipe in the stock location. It is 0411 PCM swapped using a 2002 L31 Express base tune and HP Tuned by me. The engine also has an underdrive pulley, a pair of 2008 Tahoe E-fans on a 454 dual core radiator with factory oil cooler setup. I have run Mobil one 0w40 since day one.

I have a couple of small oil leaks and a seeping freeze plug under the motor mount and plan to pull the engine to make things right.

Being so close to 400 RWHP I am going for it!

I picked up a Lunati "Bare Bones" grind cam for the LT1. It is 276/286 @ .006, 218/228 @ .050, .503/.503 w 1.5:1, .537/.537 w 1.6:1, 112* LSA, 108* ICL. I know its a slightly older grind, but its bigger than what I have and was $70.00 + shipping from Lunati on closeout.

I recently picked up a set of 5.3 coils with heatsinks and a complete 03 5.3 truck harness from a 1500. When I pull the engine I am going to pull the ECM harness and integrate the 5.3 coil harness into the stock Express harness and retape and reloom the harness. When the cam goes in I will be ordering a the 24x reluctor from EFI connection, coil brackets, and matching crank sensor. I think the old L31 distributor setup and single coil is costing me spark energy at higher rpm.

I am debating tossing a set of flattop pistons and total seal gapless rings in along with zero decking the block to make a perfect .038" quench with a .038" compressed head gasket.

To match up with the higher RPM powerband of the cam, I will be installing a 2,800 rpm 258mm billet 4L80E converter with some goodies inside from north texas converter.

Will also be switching to 4.10 gears from 3.73s.

Not sure if I will hit my 400 hp goal with a locked converter pull, but I am going to try. If nothing else it should be alot more fun to drive with the converter and gears. I am hoping the CNP setup offers better throttle response and the ability to run more than 40* of timing at cruise without misfiring like the vortec distributor currently does.

What do you LT1 experts think?

96capricemgr

iTrader: (1)

This list of mods and claimed result do not add up.

Edelbrock sells a crate engine with those heads and a cam 20degrees bigger and only rates it at 435fwhp. which is nowhere near 374rwhp though that tranny and axle.

Are your numbers flywheel not rear wheel?
Reading a spike on the graph not a real number?
Forget to mention boost or spray?
Just plain trolling?

Fast355

No spray or boost and its at the tires on a dynojet. Wish it were on the Mustang that the Van was first pulled on, but the dyno time is $$$ and the shop is always slammed.

Stock 5.7 Vortec with the MAF descreend and a drop-in K&N put down 211 RWHP and 245 RWTQ. Tuned put down 220 RWHP and 252 RWTQ with the converter unlocked in 3rd gear. With the LT4 production cam, 1.6:1 rockers, ported L31 intake, and LT1 B-car manifolds put down 281RWHP and 295 RWTQ on said Mustang dyno.

I am sure their crate engine has the crappy performer RPM cam in it and a stone age edeljunk carb on it.

I put down 330 RWHP with a 206/210 cam, stock vortecs, and stock LT1 exhaust manifolds.

Just trying to get a realistic number for the 24x CNP setup and see if anyone has had any decent results from the cam in question.

Don't need you calling me a troll.

hrcslam

Those numbers are insanely impressive for your specs. Especially through a 4L85e and 14 bolt. That's crazy high for what you have. What else did you do? Everything would have to be matched perfectly to get that out of what you have.

I'm not sure I'd mess with it. Your power could decrease. An LT1 Hot cam (comparable to what you are looking to drop in. With full bolt ons and supporting mods and tune through a T56 and 7.5" usually dynos around 360rwhp, and I've heard of 1 maybe two that topped 400rwhp. It's possible, but very very rare. And that's with less parasitic loss from a smaller trans and rear.

So you can understand the skepticism. You may want to post up a dyno sheet and video, but even then people will still doubt the list of mods being accurate.

With where you are at now, and the combo of parts you currently have, I don't think I'd change a thing because it's working very well together. Maybe if you did some head work to take advantage of the slightly bigger cam. Is it possible? Not likely, but the power you have now through your current set up isn't likely either.

Fast355

360 rwhp represents a 16% drivetrain loss, seems a little steep for a combination that typically dynos about 425 HP at the flywheel. Stock LT1 B-cars generally lose about 18% through the 4L60E and 8.5. The 4L80E and 9.5 are no more than 22%, especially locked converter 3rd gear.

http://www.gmhightechperformance.com..._2/test_7.html

Nothing real special, just locked 3rd gear pulls and a big shop fan in front to keep things cool.

The ETec 170 heads are practically identical to the Performer LT1 heads. I have seen an otherwise stock automatic LT1 vette put down 340 to the wheels with the performer heads/cam/throttle body.

Head work is not out of the question, although I am not sure it needs head work to be honest.

http://www.superchevy.com/technical/...block_part_28/

This test is what finally convinced me to go ETec170.....Gains of 17 HP over a factory L31 head on an engine not quite making 400 HP with a carb. With the 9.4:1 iron head engine I could run about 30-32* total timing before running into detonation on 93 octane. The ETecs like about 34-35* total timing. I wouldn't be suprised if they wouldn't have gained more power by adjusting the timing and jetting with the ETecs.

http://www.chevyhiperformance.com/te...st/index1.html

I am not a big fan of the Edelbrock cams or ECUs but their crate engine does quite well and I am sure it is underated.
http://www.edelbrock.com/automotive/...hevy-440.shtml

All that being said I feel the only dyno that really shows an accurate drivetrain loss is a Mustang dyno and it reads nearly exactly 10% lower than a Dynojet. 374 - 10% = 340 HP....340/.78 = 435 hp which is all I feel this setup makes at the crank.

96capricemgr

iTrader: (1)

I will say I didn't read all that. Since you want to dismiss the crate motor I mentioned let's look at the Edelcrap LT1 packages, the LT1 kit is 396fwhp and their LT4 kit is 406fwhp, which at 22% loss is 308 or316rwhp respectively.

So you are claiming your lower duration cam and whatever intake is worth 70-80hp over Edelbrock's cam with the same heads.
Now granted Edelbrock suff is not as good as it should be, their LT1 stuff in particular is a joke, but you are the one that compared your heads to the LT1 offering.

See why someone looking at this objectively does not believe this?

Fast355

I dismissed the carbureted crate motor and even posted a link to the 440 HP 350 crate engine edelbrock sells with their crappy multi port fuel injection setup on it. Its a ZZ4 with Etec170s and a little bit more cam. You and I both know its not just duration that makes a cam run and Edelbrock cams are LAZY compared to a Comp or Lunati.

They do not even mention what headers or exhaust they are testing their crate engines with and most of us know what happens when multiple header designs are tested on the same engine.

Most of us know Tri-Y headers have a unique ability to add alot of mid-range torque and HP.

I even made mention I do not believe the engine makes more than about 435 HP at the flywheel.

The cam I am running is better than the LT1 Performer cam and I already posted a link with the untouched ETecs making 485 HP on a 350 and outperforming a 200cc intake port across the whole rpm band.