Help me build a great street combo

Lawrence454 · May 25, 2016

Here's the deal I came across for only $2500 :

1) LQ4 running engine with 90,000 miles. It came out of a wrecked truck and it was running good when pulled.

2) A new set of LS3 cnc ported heads with offset intake rockers . I know these heads are BIG for a small cam. That's ok, they rock at 5000+ rpm.

3) A Holley single plane intake

I want to build a 480 to 500 hp street engine that will idle as smooth as possible.
I plan on using an automatic trans ; 4L80 with TCI controller.

I also plan on using a carb for now. The changeover to FI is more work and at least another $1500.
So I will probably trade the single plane intake for a dual plane like an edelbrock rpm.

So how much cam will I need to reach 480? >

I'd like to keep a stock torque converter in the 4L80e if possible.

Legeance · May 25, 2016

I'm no expert but anything I say could be wrong, LQ4s make like what 335HP stock? With the heads swap it will boost it a bit but I had an LQ4 that was running a z06 cam and it made just about 370(crank power) so you would need a pretty fat cam. Also, try doing some minor things like swapping the springs in the heads if you're gonna run a bigger cam. Also, run 3in exhaust over 2.5 I've always seen better numbers with the 3.

Side note, you might loose a bit of power not running FI.

Vega$69 · May 25, 2016

Carbed with make more peak then EFI although you won't have the same drivability.

Mill the LS3 heads to get compression up and use a low lift high duration cam like the GM performance hot cams used in the 480 and 525 LS3s. Will not have to cut Pistons. 2.5 exhaust is fine unless you just want more noise. Go to the dual plane sooner then later.

Don't go crazy on the stall and you'll have a great driving street machine.

Lawrence454 · May 25, 2016

Vega$69 said:
Carbed with make more peak then EFI although you won't have the same drivability.

Mill the LS3 heads to get compression up and use a low lift high duration cam like the GM performance hot cams used in the 480 and 525 LS3s. Will not have to cut Pistons. 2.5 exhaust is fine unless you just want more noise. Go to the dual plane sooner then later.

Don't go crazy on the stall and you'll have a great driving street machine.

Sounds good. :smile2:

The LS3 heads have 70 cc chambers which I think would put the compression around 9.7 to 1 (stock heads have 73 cc chambers- 9.4-1).

What about this ? I was thinking about buying a set of stock LS3 pistons 4.065" bore - $250 on ebay and boring/installing them. That's the most an LQ4 block can be safely bored.

That should help the heads flow better and add 12 cu in or so.

And the added cubes might help compression enough so the heads won't need to be milled ?

DOUG G · May 25, 2016

LS3 heads on a LQ4 and any decent cam will need the pistons fly-cut.(intake valve size)
LQ4 with stock heads and a decent cam can/will get you there.
LQ4 heads are 72ish cc
LS3 heads are 69ish cc
Some other factory heads are better choices, but again, may need to fly-cut with any decent cam.

Everett#2390 · May 25, 2016

Build for torque.
Dual plane, EFI, small stall convertor - 11 or 12 inch, 1.87 inch headers w/long collectors & X-pipe,
Most important - lose weight in the car = free power.

Lawrence454 · May 25, 2016

DOUG G said:
LS3 heads on a LQ4 and any decent cam will need the pistons fly-cut.(intake valve size)

Another good reason to install the LS3 pistons:

Avoid fly-cutting; bigger bore works better with the LS3 heads and 12 more cubic inches.

Sounds like a win, win, win :smile2:

Yes, I will sell the single plane and go with the performer rpm.

DOUG G · May 25, 2016

LQ4/LS3 combos with good cams and fly-cuts are in the 10's.

Just haven't sorted out mine yet

LS2
750 carb
1-7/8 headers, full 3" exhaust
Th400
4k stall
4.56 gears
28x9 slick
2750 race weight
233/244 .619/.595 110+3
I put a super vic on, some 28x10.5s and made a few passes last week. 60' was off but car still ran 10.15@132

I'm about 600# heavier, bigger cam, more stall, but less gear, so 10.7's look do-able

Lawrence454 · May 26, 2016

Doug: LQ4/LS3 combos with good cams and fly-cuts are in the 10's. Just haven't sorted out mine yet
-----------
I'm late to the LS party. The horsepower per cubic inch is amazing.

The 454 that was intended for the Camaro is going into a 67 Chevelle I recently bought.

Not sure how long that 454 will remain in that Chevelle >

Lawrence454 · May 26, 2016

A stock 6.0L iron block, L92 (LS3) heads and a small Comp Cam (228/230)

gave 551 hp. Wow.

Testing The New GM L92 Cylinder Heads - Car Craft Magazine

Vega$69 · May 27, 2016

Lawrence454 said:
A stock 6.0L iron block, L92 (LS3) heads and a small Comp Cam (228/230)

gave 551 hp. Wow.

Testing The New GM L92 Cylinder Heads - Car Craft Magazine

Last month, we baselined this engine with a GMPP Hot cam using the stock, iron 6.0L heads, and it made a stout 483 hp.

The GMPP Hot cams are only 525 lift. The LS3 heads like duration more then lift and are very streetable.

dondb · May 27, 2016

I have an LQ9 factory lower end, with a set of LS3 heads with a comp cam 273LR .610/.617, 223/231, LS3 FI system, 92 MM TB and Spectre cold air intake. Finally had it tuned by slow hawk and I got 408 HP, 388 TQ to the rear wheels on a mustang dyno. Looks like the smaller cam set up would of made better HP and TQ! Sounds great and pulls like a champ...not sure if the HP and TQ can be that much of a difference from rear wheels to flywheel? So my vote would be the Comp Cam in your build.

Lawrence454 · May 28, 2016

Vega$69 said:
The GMPP Hot cams are only 525 lift. The LS3 heads like duration more then lift and are very streetable.

I just got home with the engine/parts that I bought from a friend at work.

1) The cnc LS3 heads (are beautiful- still in the box)

2)He also threw in a set of Crane 1.8 roller rockers which will put the hot cam right at the max recommended lift of .550"
3) There was the 1999 6.0L Silverado engine and
4) a new victor jr single plane in a box.

The engine still had the intake and injectors. I doubt those injectors could support 480 hp but I will investigate that.
And that year engine had the cast iron 317 heads , so I will try to sell those.

I plan on running a 750 carb and performer rpm intake. Strongly leaning toward the 750 street demon. I like the design of them and the guys at Team Chevelle like it a lot.

Lawrence454 · May 28, 2016

Everett#2390 said:
Build for torque.
Dual plane, EFI, small stall convertor - 11 or 12 inch, 1.87 inch headers w/long collectors & X-pipe,
Most important - lose weight in the car = free power.

Are you saying I need to lose weight ?? >

Great advice (as always) :laugh:

Lawrence454 · May 28, 2016

dondb said:
I have an LQ9 factory lower end, with a set of LS3 heads with a comp cam 273LR .610/.617, 223/231, LS3 FI system, 92 MM TB and Spectre cold air intake. Finally had it tuned by slow hawk and I got 408 HP, 388 TQ to the rear wheels on a mustang dyno. Looks like the smaller cam set up would of made better HP and TQ! Sounds great and pulls like a champ...not sure if the HP and TQ can be that much of a difference from rear wheels to flywheel? So my vote would be the Comp Cam in your build.

I don't know how "reliable" these dyno hp measurements are. I bet yours is higher than that.

Probably the best measurement is on the track.

Help me build a great street combo

Lawrence454

Legeance

Vega$69

Lawrence454

DOUG G

Everett#2390

Lawrence454

DOUG G

Lawrence454

Lawrence454

Vega$69

dondb

Lawrence454

Lawrence454

Lawrence454

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