LQ4/LS3 suggestions
02-21-2018, 03:58 PM
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LQ4/LS3 suggestions Hi Folks,
Fairly new to the LS stuff, but digging right in. The engine will be going into a street/strip Pro Street 71 Vega. Car weighs in at 2620. Picked up a complete LQ4. I'd like to see 550 at the crank, 450 at the tires. Planning on staying NA. I'd like maximum HP around 6500 with a 7000 shift point. The plan is to rebuild it with good rods, forged pistons and factory crank. I've been slowly collecting parts as funds permit. I have a fresh set of LS3 (821 casting) heads with BTR 660 springs, and new LS7 lifters. That's all I have at the moment. I'd like to run it on pump gas. Been doing quite a bit of research on the induction system, and i'm planning on staying with fuel injection. I like the idea of running a single plane style intake due to the looks. I like the idea of looking like a traditional carb setup with all the benefits of EFI. I don't want to go with a TBI setup, i want to stick with the port injectors. I'm questioning the drive ability of the single plane and I've read mixed reviews. Some say it's a non issue, some say I'll give up quite a bit of low end and midrange power. Am I better off going with a plastic OEM style intake and if so will a factory LS3 intake make the kind of power I'm looking for ?? I have the Engine Analyzer and Drag Racing Analyzer software that I just started using to help with the combination. Sorry for the long story, but I wanted to give everyone some good overall details. Any and all suggestions will be very much appreciated.
Fairly new to the LS stuff, but digging right in. The engine will be going into a street/strip Pro Street 71 Vega. Car weighs in at 2620. Picked up a complete LQ4. I'd like to see 550 at the crank, 450 at the tires. Planning on staying NA. I'd like maximum HP around 6500 with a 7000 shift point. The plan is to rebuild it with good rods, forged pistons and factory crank. I've been slowly collecting parts as funds permit. I have a fresh set of LS3 (821 casting) heads with BTR 660 springs, and new LS7 lifters. That's all I have at the moment. I'd like to run it on pump gas. Been doing quite a bit of research on the induction system, and i'm planning on staying with fuel injection. I like the idea of running a single plane style intake due to the looks. I like the idea of looking like a traditional carb setup with all the benefits of EFI. I don't want to go with a TBI setup, i want to stick with the port injectors. I'm questioning the drive ability of the single plane and I've read mixed reviews. Some say it's a non issue, some say I'll give up quite a bit of low end and midrange power. Am I better off going with a plastic OEM style intake and if so will a factory LS3 intake make the kind of power I'm looking for ?? I have the Engine Analyzer and Drag Racing Analyzer software that I just started using to help with the combination. Sorry for the long story, but I wanted to give everyone some good overall details. Any and all suggestions will be very much appreciated.
02-21-2018, 04:39 PM
#2
You can make 450 rwhp with the stock bottom end pretty easily. Take the money that you were going to put into the rods and pistons and get your heads ported. Then get yourself a cam and pushrods to properly utilize the flow of the heads. Slap on a LS3 intake w/ what I assume would be a DBC TB for your build, optimize your exhaust, and you should be set for a nice road car that makes good power everywhere.
02-22-2018, 08:20 AM
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My thought was to upgrade the rods and pistons for a bit of insurance figuring who knows what the future holds. Do you think the un-ported LS3 heads and intake will support the power i'm looking for ?? Yes it will a DBCTB. Thoughts on the single plain intake ?? Thanks
02-22-2018, 08:57 AM
#4
With a light car I don't see a single plane intake being a problem at all but you left out some key details.
What Transmission? If auto what stall?
What gear ratio and tire size?
In my opinion given you have a lightweight car and want peak hp at 6500 you're likely going to run a 3600 or higher stall if it's an automatic, If that's the case you'll likely be faster with a single plane over a dual at the track and likely won't be able to use all the power on the street anyway.
What Transmission? If auto what stall?
What gear ratio and tire size?
In my opinion given you have a lightweight car and want peak hp at 6500 you're likely going to run a 3600 or higher stall if it's an automatic, If that's the case you'll likely be faster with a single plane over a dual at the track and likely won't be able to use all the power on the street anyway.
02-22-2018, 09:20 AM
#5
Before you invest money in your build I suggest you look at some of the NA junkyard builds. We put a bone stock (except china intake) 155,000 mile LQ4 my son in-law put 73 Nova, Stock 4l80e with a yank 3600 stall and long tube headers. 3.73 gear and I think his rear tire size in around a 255/60 15" It will blow the tires off pretty easily even in 2nd gear.
These motors stock take quite a beating and with your power goals you could look for a good used engine and leave the bottom end alone, If it has good oil pressure I wouldn't even change the oil pump. Basically stock untouched short block, Change cam, Intake and have your 823 heads ported or sell them and buy a decent set of aftermarket heads. This should get you very close if not past your 550hp at the crank goal.
Once up and running you can always start buying parts for a forged shortblock while playing with your budget combo.
These motors stock take quite a beating and with your power goals you could look for a good used engine and leave the bottom end alone, If it has good oil pressure I wouldn't even change the oil pump. Basically stock untouched short block, Change cam, Intake and have your 823 heads ported or sell them and buy a decent set of aftermarket heads. This should get you very close if not past your 550hp at the crank goal.
Once up and running you can always start buying parts for a forged shortblock while playing with your budget combo.
02-22-2018, 09:31 AM
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I'll be using the turbo 350 (no trans brake) I had in the car with the previous Gen1 350 sbc. The current converter is a 8" ATI. With the Gen1 engine, I was getting a 4500 stall flashing the converter off the foot brake holding the car at 2000. Rear gear is 5:38 with a 33 inch tall tire. I'm hoping the LS will make enough additional torque (more then the 350) so i can tighten the converter, and lower (numerically) the rear gear making the car more streetable while not giving up any performance........maybe i'm asking to much for a NA engine.....
02-22-2018, 11:07 AM
#7
I guess that depends on what your previous engine made power wise, The old SBC had to be built to make decent power and the stock heads weren't good at all. The LS heads are comparable to what many considered race heads for the old sbc.
I still don't see the single plane intake hurting performance, Even dropping to a 3600 you're still in the rpm range where a single plane shines.
I don't know if you want to cut your floor for a transmission but a 4l80e would give you overdrive and the ability to run a lock up converter to help street driving and easily handle the power your making with a simple shift kit. If your running a stock computer to run everything then it will also control the transmission.
Your power goals are lower than what most people are looking to make and should be pretty easy to exceed with good heads. If you have E85 available then you could bump up compression considerably.
I've been doing this for a long time and the LS engines are better than a sbc in so many ways. It's really a night and day difference in design. Back in the day if you wanted to go fast you pretty much started out with a bare block and bought everything else and were lucky to make 500hp at the crank. With the 6.0 LS you can pretty much keep it all stock except the cam, Then have the stock heads ported and milled for a little more compression and you should be making close to if not more than 500 flywheel hp and do it reliably.
I still don't see the single plane intake hurting performance, Even dropping to a 3600 you're still in the rpm range where a single plane shines.
I don't know if you want to cut your floor for a transmission but a 4l80e would give you overdrive and the ability to run a lock up converter to help street driving and easily handle the power your making with a simple shift kit. If your running a stock computer to run everything then it will also control the transmission.
Your power goals are lower than what most people are looking to make and should be pretty easy to exceed with good heads. If you have E85 available then you could bump up compression considerably.
I've been doing this for a long time and the LS engines are better than a sbc in so many ways. It's really a night and day difference in design. Back in the day if you wanted to go fast you pretty much started out with a bare block and bought everything else and were lucky to make 500hp at the crank. With the 6.0 LS you can pretty much keep it all stock except the cam, Then have the stock heads ported and milled for a little more compression and you should be making close to if not more than 500 flywheel hp and do it reliably.
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02-22-2018, 11:31 AM
#8
I did a quick search and this was one of the first results. The engine 6.2 that made 605hp NA
Short-Block: Chevrolet Performance LS3 crate engine, flat-top pistons (no valve reliefs)
Heads: Trick Flow Specialties Gen X 255 LS3 with dual valvesprings (flow 380 cfm)
Cam: Stock BTR/Comp (0.624/0.590 lift, 232/248 duration, 114 LSA) and three-bolt gear
Rockers: Stock Offset LS3
Intake: Speedmaster LS3 Individual Runner
EFI Management: Holley HP
Exhaust: 1 7/8-inch Kooks headers
http://www.superchevy.com/how-to/eng...00-horsepower/
Short-Block: Chevrolet Performance LS3 crate engine, flat-top pistons (no valve reliefs)
Heads: Trick Flow Specialties Gen X 255 LS3 with dual valvesprings (flow 380 cfm)
Cam: Stock BTR/Comp (0.624/0.590 lift, 232/248 duration, 114 LSA) and three-bolt gear
Rockers: Stock Offset LS3
Intake: Speedmaster LS3 Individual Runner
EFI Management: Holley HP
Exhaust: 1 7/8-inch Kooks headers
http://www.superchevy.com/how-to/eng...00-horsepower/
02-22-2018, 11:36 AM
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Not afraid of the 4L80e, just not in the budget. The trans I have is built so why not use it. Overdrive would be nice, but realistically I don't see me using it much. The street time will be all local stuff for the most part. Local cruises, swap meets that kind of thing. Track time and long distance events is what the trailer is for. If I find a deal on a O.D. trans then great, if not...... My goal is a low 10 second time slip, thru the mufflers, all street equipment hooked up and working just as it's driven. Car was running high tens with the old small block. I never had it on a dyno, but my math says it made 425 at the flywheel. That was with cast iron factory heads with some home porting.
02-22-2018, 01:07 PM
#12
Cam = 229*/242*, 112* + 0*, .668"/.668" lift
Heads = Ported OEM by Texas Speed
Headers = Mid-Length (actually, more like shorties) 1 3/4"
Exhaust = 2 1/2" with cats
OEM Intake and OEM TB
Dyno and street tune
I'd bet a similar cam with stock heads and 1 7/8" longtubes (and a tune) would get you to your goal.
KW