New To LS Engines/ LS3 427 or LQ4/9 402?

Howdy Ya'll I am new to the GM LS engine series.

I am saving/planning to build an Old School Pro-Street car.

I would like to build a carb'd E-85 LS engine from a shortblock.

Which do Ya'll recommend a LS3 based 427 or LQ4/9 based 402?

Nice to be here.  

All depends on what you are putting it into, and what you plan on doing to it. If you are keeping it naturally aspirated or under aprx. 750-800rwhp then i would highly recommend the LS3 427. Thats the route I'm going next spring now that I've pushed my LS2 6.0 as far as it will go on the stock rods/pistons.

You will save at least 150-200pounds by using the LS3. The LQ is VERY cheap to buy though, and ultimately handles more power due to its higher strength.

Though 98% of the people who buy LQ's never make the required 900+ crank hp to justify the extra weight of a iron block and heads.  
'05 GTO: 3600 stall, Comp Cams, L92 heads, etc. etc.

'06 ZX14: lots a mods

I am still at the saving/planning stage but I am thinking about an unusual list of candidates like a 1970's Ford Maverick or Mustang II,1980's Fox Body Mustang, Datsun 240/260/280/300ZX,Mitsubishi Starion/Chrysler Conquest,1970's Chevy Vega/Monza,Ford Pinto Wagon, 1970's Chevy Camaro, 1980-1990's Mazda RX-7, Plymouth Laser/Eagle Talon/Mitsubishi Eclipse 1990-1994.

It would be nice to have a streetable 10 second N/A / 9 second N2O car.

If I run pump E-85 it will allow for a 11-13:1 CR with it's 105 octane.

Rocket Brand racing fuel has an E-85 that is 112 octane.  

A 427 LSx will make 500-550rwhp in perfectly streetable form and put even a relatively heavy roll caged Camaro (3400-3600 w/cage) into the mid 10's with a 1.50 or quicker 60' time.  Any of those other car choices will weigh in at or under 3000 pounds wet: that will put you in the low 10 to possibly high 9 second range.  All with 11 to 1 compression on normal 92 octane unleaded gas.  Toss that E85 idea out the window, it's not needed for daily driver N/A builds like yours. Besides, ultra high compression that would require E85 like you are planning also benefits/almost requires large cams and crazy unstreetable builds.

For the record, two friends of mine just hit 10.7's: one in a caged 01 WS6 Firebird (weighed 3700 w/driver) utilizing a 408ci, 11.1 to 1 pump gas setup. Other was a '05 GTO A4 with a 408ci 11.0 to 1 pump gas setup (3850 w/driver) with a 4000 stall converter and 128mph trap speed.  Both guys made 500rwhp on pump gas.  "Just Saying"  
'05 GTO: 3600 stall, Comp Cams, L92 heads, etc. etc.

'06 ZX14: lots a mods

I saw an ad advertising 416 LS3s(+.005 overbore,4 inch forged crank/6.20 inch forged rods).

If I used ported L92 ,ProComp,or Patriot heads,Victor carb'd intake,800 Holley double pumper,mild solid roller cam could I expect 600+ HP at the flywheel?  

Only a few heads on the market outperform a mildly ported set of L92/LS3 heads.  And NONE beat the price to performance ratio. Only issue is valve to piston clearance with big cams: if you want to go 11 to 1 compression or higher, with a cam bigger than aprx. 234 dur. @ .050" on the intake side you will need pistons that are fly cut.

If I were you I would go with something like this:

ported L92 heads milled .030" to .040" w/ hollow stem (GM LS3 or aftermarket)intake and SS exhaust valves.

11 to 1 CR, still be 92 octane pump gas friendly with .040" fly cut pistons (L92/LS3 heads require L92/LS3 fly cuts!! Cathederal port heads like the LS1/2 are in a different location).

Professionally spec'd hydraulic roller in the 234-238 dur @ .050" for street/strip, or 238-242 range for more strip biased. skip the solid roller (thats old school and totally unnecessary unless you want to spin your engine above 7500rpms just to eke out the last few possible hp- and like replacing valve springs yearly along with checking valve lash semi annually). Expect to hear the lift specs in the .610-.670" range because thats what L92 heads like.

GM carbed L92/LS3 intake. Port it if you are going with the more strip orientated cam. Don't believe anyone else makes a L92/LS3 carb intake yet?

900+cfm Holley HP or Demon carb. 800cfm is too small and will restrict you. Welcome to the LSx small block world!


CRANK HP:  Obviously lots of variables, but with a properly spec'ed street/strip cam you should expect to be at or over 600hp.  With the more strip orientated setup you can expect up to 650hp or more. I'm basing those crank hp numbers off of similar car builds I've seen at the tires, with a 15% assumed parasitic hp loss.  Loss will be alot bigger if you dont run 1 7/8" long tube headers, free flowing exhaust, and some kind of cold air intake to keep the hot engine bay air out of that carb!  
'05 GTO: 3600 stall, Comp Cams, L92 heads, etc. etc.

'06 ZX14: lots a mods

if on a budget do the lq4/9 with l92 heads.get a custom cam from EPS.the ls3 is bigger bore ,which is better but cost more.whats your budget?