LS vs Big Block
 

That should get every ones attention. I admit I have been busy with other hobbies lately so I have not been on this site in a while but I remember this being a hot topic to some of you a while back. Well I just wanted to sure this link with you guys to check out. A 490+ cubic inch naturally aspirated cathedral port LS motor making about 800 hp at 6200 rpms and over 600 ft lbs across the entire pull. I only wish they also posted the dyno sheet. Well here is the link if it works:

http://www.enginelabs.com/news/video...00-horsepower/

Is this on race fuel? I would think so but fuel is not mentioned anywhere.

I think the LS platform would be a great combo with SCX drives in smaller twin engine cats. The weight savings with an aluminum block would be huge.

Thats a sweet setup! I had a LS base engine I built a few years back the biggest thing was the expense of every part. I never got to convert to the carb setup like they did thats big $$. Being a 6 bolt main style block they are tough though. If your looking to get a stand alone engine with the EFI & wiring harness look out! I sold mine after I wrecked the car & broke the corner off the block & damaged the head still got $3500 out of the engine parts & EFI & wiring harness. Although that being said I had about $1500 onto cam, springs, ECM, couple other small mods & got to 575 hp pretty quick & very easy. If I had the extra cash I would swap out my NA SBC's for a pair of carb or EFI LS's for sure!

Dry sump, front distributor drive conversion, obviously with 493 inches some sort of stroker crank big bore set up be interesting to the the cost. And the race gas question too.

I'm a skeptic until my son started fooling with the one in his truck.He has a 6.0 in his truck stock bottom end comp.valve job cam,springs,headers with a procharger and a Tune.It makes so much power it is hard to control.It's a 2003 shortbed GMC pick up automatic trans.Runs High 11's at the track.Daily driver Way faster than any chevelle that my buddy has had and they had some pretty strong big block 454 and a 496 and a 502 in them.He has always said these motors in a boat would be bad ass,but the marine parts are so high.These motors weight nothing compared to a big block. Just my 2 cents. JOHN SR

Loving it!

Actually the parts are not that expensive anymore. I thought about putting a stock LQ4 6.0 in my parents 242 LS to replace the SBC that is in there now. The exhaust manifolds would cost about $1000.00 Not really that bad considering a good set of exhaust manifolds for a SBC would be about $500.

Could Bob Madera grind a custom cam for one of these?

Both Ilmore and Crusader are now building marine LS motors, so there should be more marine parts to choose from now...

Volvo Penta and Indmar have also replaced the 8.1's in their lineup with a LS engines. The 380hp Volvo LS engine outruns their old 8.1Mag.

The only marine propulsion manfacturer that does NOT offer LS engines is--------Mercury Marine.

Some are pretty pricey http://www.turnkeyenginesupply.com/c...treet-Engines/

LSX power any day over big blocks. I am a bit biased though...
http://img.photobucket.com/albums/v7..._3789251_n.jpg

This is the last one I built. Last I heard, it was still kicking a$$ in Canada. When you can pull an engine down with 100k miles, nearly a thousand lbs of nitrous ran through it, and still has cross hatching showing in the cylinder bores it tends to make you a believer. I got hooked on them when they first came out and built more than I can remember. As reliable as an anvil (except for the LS1 sleeved big bore engines I dealt with).

i have a ls 418 that pulled 642 hp on 93 pump gas, with a carb ,in a chevelle .BUT i dont think the torque numbers would hold up on low end like a bigblock . in a heavy boat , large boat i would still take my bigblock .

i agree with kennyd,the ls is a great engine,and in a smaller liter boat,i see lots of potential,but good old bbc torque is still king imo.

He sure can!

i guess im old school but in my opinion there is no replacement for displacement. a NA 572 or 598 with a 1050 carb will make atleast 750hp on pump gas. even if your boat is simi small the extra torque from a big block is huge. a punched out and slightly stroked version 632 will make 800-850hp with tons of torque on 93 gas. there is also the option of aluminum big block for weight. i cant tell you the difference in price though cause ive always gone big block. just my 2 cents.

bbc

http://www.onedirt.com/news/spotligh...i-crate-engine :daz:

First of all let me state that I am skeptical of the results claimed in that article. Second, it is true they did not specify what type of fuel so I guess it is possible it uses race fuel. That said if the numbers in article are accurate, I think it would be difficult for BBC to match those tq numbers without 600+ ci. Keep in mind they are claiming over 700 ft/lbs of tq from 4000-5900 rpms with a peak of 754 ft/lbs at 4500rpms. And they claim over 600 ft/lbs for the entire pull, of course they do not mention where they started the pull, but with peak tq at 4500 and pk HP at 6200 I seriously doubt it is lacking anything down low. Also the claimed number are allegedly through an 850 carb. That is impressive. No doubt this motor was a high dollar build, including the RHS tall deck block (not sure if that is the billet one or not), high dollar crank and rods, but the heads are relatively cheap out of the box, that carbed intake can be had for less than $500.00, and a ignition controller (not the distributor conversion they are using) can be had for $300.00.

Before the LSx crowd gets the panties in a bunch, I have owned a couple in automotive applications. One of my younger brothers has a LS2 based forged 402 ported LS3 headed .620ish cammed nasty iin his 05 GTO. Every time I drive it I think man, this thing is stupid fast. It pulls low 11's in the 1/4 and he drives it to work almost every day. He has 50K on this build and other than being really hard on valve springs ( square lobed hydraulic rollers do this) it has been super reliable.

GM never built an LSx over 427 CI for a reason. The LSx engines can be spun up and produce great HP but that alluminum block will not hold up in a marine application. Big tourqe LSx engines are built off of the iron block LQ9 truck engines and have lots of boost applied. They can handle that well in a automotive application but a marine application put stresses on an engine from idle on up that the LSx engines were not designed for. When you start talking about aftermarket blocks and unlimited CI's everything changes but yet stays the same. What it really comes down to is cost to repower. Most people can reuse all of their accessories when repowering with a healthier BBC. Making the swap to an LSx engine will require all new accessories, i.e. exhaust manifolds, accessory drives and brackets, engine pounts, bell housings etc. This will double the cost of making the swap.

The LS is not a good choice to replace a big block in a BOAT above about 550 hp. Its a great choice below 550hp.

the advantage to the LS is the volumetric efficiency and lower weight of an alum block and heads.

The bore that works the best to unshroud the valves is 4.065...the biggest crank to live in the alum block is 4" so thats 416ci. The combo I would build is the alum ls3 with ls3 heads, incolnel and stainless valves, forged internals, closed cooling, with variable valve timing to increase the low end power needed in a 1 speed boat. That makes about 550 hp at 6k rpm.

any more power than that will be with rpm at the expense of torque...again a boat is like a car stuck in 4th gear...so the boat auto comparison does not work well here.

boost will give more power across the rpm band but kills longevity, price, and fuel economy compared to a N/A bbc...you will want an iron block to run boost so there goes alot of the weight savings.

There is a good reason that Raylar, MAST, ILMOR all make mid-upper 500hp marine LSx engines.

Merc tested the off the shelf GM ls engines but in stock auto form they are not as good as a BBC. either not enough torque (stock ls7), not strong enough to live in a boat (stock ls3), drinks too much fuel and has a short life (stock lsa).

weismann marine has done very well with stock ls7's but that is due to the 6spd TRANSMISSIONS. stronger build and low end power are needed in a boat build compared to a car/truck...thats why the LSx engine that is ruling auto drag racing only has a small place in marine compared to BBC.

LS has its place and will find it. One would be perfect in my 22 donzi classic.

IMO smaller cats should be the candidate for LS engines, light weight, high RPM high torque is required as much as high RPM.

Most marine BBC in the 700-800 HP range are supercharged engines that make 500-550 HP NA. If the LS is a better choice up to 550 HP NA why not supercharge it and be the better choice at 800 HP?

Katech LSX 500 CID, 600 lbs/ft from 3000 RPM, 675 HP @ 5900 RPM, mild cam. Affordable, reliable, complete with an accurate SAE dyno sheet. Makes for an interesting comparison stacked up with a conventional 502 BBC.
http://youtu.be/aE576x32yJA

Wow this is some good information and answered the question i woke up today thinking as I looked out at my engineless 25.5 IMP Eleganza (yea old boat i know compared to you guys) But I was considering this as a alternative to weight loss on the Pig with the LS2 Stroker 408. Which I have readily available. But looks like i'll continue with my 454 rebuild and exhaust worth more than the boat build! :lolhit: I also agree with the big block producing more torque at low end then the under 416ci. engines. But i'm also not up to par as to whats available to the LS world. But catching up!

Remember to factor in the usable rpm ranges between an LS and BB package when making flywheel torque comparisons. A 10% or 15% gearing (or prop) change can make a big difference. The availability of variable cam-timing on the LS is a big factor as well.

I don't agree the LS is limited to 416. The intake valve is 2.20 inches and with a 4.185 bore and 4.125 stroke you are at 454 cu. inches- the same as the venerable BBC. The increased efficiency of the LS ports will give you MORE torque, better rpm range also. The way I would go is with the iron LSX block for durability and it will still be lighter than a BBC.

Wannabe

I know the LSX isn't limited to 416 as I've only owned a couple ls2's and one LS3. But I have never had the opportunity to work on anything bigger. I know the LSX427 are some awesome runners! But pricey too- at least for me. Not to :hijack: the thread either as I may wonder with running LSX/2/3. I know some of these especially Running forced induction have had great success on E-85. Anybody tried this even though fuel consumption i know is horrible and e-85 also has moisture issues?

I agree 100%.

While I agree the aluminum blocks would be good in a light and efficient cat, a stroker iron block motor can be done for the heavier Vees that you can throw tons of boost to reliably. There are also tons of twin turbo LS7s out there throwing down 1,000+hp. As far as the reliability of LSX engines go, just remember where there design came from. For all the naysayers, just wait til Skate gets his new boat dialed in.

I will put a ls based motor up against a big block torque for hp any day I have hade 450 cubic in aluminum block
Motors in my cat for 5 years still going strong getting 2 miles per gallon no one has touched on the fuel mileage of these things put a big block to shame my two cents worth I just ran a ls7 which is 427 cubic in with the ls9 blower from gm on 93 oct gas 12pounds boost made 850 hp at 6600 rpm and 825 torque at5300 rpm this monster made 800 ft lbs at 3500 rpm and will fit under a corvette hood will post pictures and Dyno sheets tomorrow

This I wanna see! Officially subscribed to this thread! Any links to videos would be awesome too! And exhaust setups!

My motors are na Sams boat will be interesting he is using the Cadillac blower motors he will be impressed I can tell you that right now and he is going to think his gas gauge is broke

Go to Thompson automotive website good videos

The exhaust was stock ls7 corvette I just did a test yesterday on a ls7 stock motor except for a little larger cam and valve spring change we made 660 hp at 6600 rpm and 560 ft lbs at 5200 rpm we put on a set of headers and the stock ls7 corvette manifolds no difference this was a bone stock motor pump gas you can put a fast intake on this motor and pick up 20 hp the motors are just fffffffuuu cool when was the last time they redesigned the big block never the ls7 motor is the motor of the new millennium just get it

OK I'm very open minded on this subject and want to share an experience. I am 60 and grew up building hot 327's/350's as a kid and remember when the MK IV 396 came out in '65 in a few Impalas and Chevelle's...427's in '66 and the rest is history. I had an LS6 460 Horse SS 454 Chevelle in 1970 and it was hard to beat.

The BBC has been the architecture of choice for go fast marine propulsion as well as large cruisers 40' and under. One of Sea Ray's best sellers ever was the 34' & 39' EC with twin 454/330 horse BBC's on BW transmissions. A 34 EC will make about 35 MPH with that power and suck gasoline like you wouldn't believe!!!

Up until 2010 I had a Sea Ray 40' EC with twin 400 horse Cat 3208's that ran 30 fairly easily and used roughly half the fuel that a 34' w/454's or 502's would. One day I was at my marina in North Palm Beach when a very nicely restored '89 Sea ray 34' EC pulled in. It caught my interest so I did what we all do...I got a closer look. The owner was more than happy to share what he had done. i went aboard and he opened the hatches in the cockpit floor to reveal a pair of marinized LSA Small blocks!!! He had them mated to a pair of Hurth/ZF transmissions with 2" prop shafts!! The LSA'a are set up closed cooling and I have to tell you...in a 12' beam boat they looked lost in the bilge!!

My first question was how does it run? The owner was a retired engineer and knew his stuff. He explained that you have to understand he saved 1000 lbs of weight in the boat and almost doubled the power and torque....so let's go for a ride!!

We left the dock, pulled out into the ICW and idled thru the "No Wake" zone. Once we cleared he offered the helm to me which I couldn't get to fast enough. I eased into the throttles with tabs down and this 7 ton beast jumped on plane like a ski boat. Trust me...getting all that iron out of the bilge of that boat makes a huge difference. I saw 40 with the tabs still all in at 3800 RPM. I got out of the tabs and the 34 jumped to 45 without touching the throttles. I looked over and he gave me the nod so i let it all out...56 MPH at 5200 RPM!!! I backed off to about 4800 and held 52~53 no problem..Flow Scan showed 30 GPH TOTAL!!:evilb:

He confessed that he spent just north of $40K on the boat in the re fit but there was a large portion of that total in new upholstery, electronics, etc.

In summary...I was sold on the LS idea that day. That boat accelerated like an out board ski boat and was a full 20 MPH faster than it had been with the original power...using considerably less fuel!!

I know the 34 EC isn't a hull that any of us would choose as a "Go fast" set up but imagine this set up in say a Formula 370 SS with steps!!??

I think we are in the midst of a "Paradigm Shift" in Marine Propulsion and the LS architecture has taken a strong lead.

Interesting thread. Having just bought an LS Camaro several years ago, I suggested the same thing over on Performance Boats forum. Even though it seems the membership is mostly comprised of smaller boats owners, I was greeted with "boos and hisses, bad idea, it'll never work" ,etc.

I'm laughing about it now! :)

Thompson Automotive is who Chevy had build a 2,000 HP Turbo LSX engine. They did it, and said there was still more power to be had.

Wannabe

Well said! A LS based engine can be a great package for most boats. I'm not going to say they would replace a 1500hp Sterling. Just because I don't want to pretend to know that level of power. Any thing under 800hp the LS based power plant can out shine a BBC. Wether fuel consumption, HP to weight or just unbelievable HP/Torq youll find something. Not in every aspect but overall if you mess with these motors you will be amazed. Ask the Ford guys more LS powered Mustangs at the strip than you see Ford powered (JKing). Breath breath ford guys:)

I have two 588's that I was freshing up to put in my boat. I started doing the math and some lightly boosted LS3's will be 600hp easily. They will also be EFI and the Stock ECM will work in this application. Then guys are running these motors at 15-18PSI of boost on stock bottom ends and stock head gaskets. They are doing this on 91 and Meth Inj. Some guys have played with E85 but I think they have went back to Meth because of lots of negative things about E85. I'm not sure about using Meth on a boat but I'll find out. (If you have tried it I would like your opinion on Meth Inj). I'm not saying that boost levels or stock bottom ends will work in a boat but LS's DO work in boats.

Now the comment that Mercury tested the LS motors and they weren't strong enough? Might be more politics then anything. I tow my 34Ft boat with a 6.0L that pulls it 80mph. I couldn't have towed it with a 7.4L with out lots more fuel and overheating it. I never had a 454 that went over 125k that wasn't desperate for a rebuild. GM removed the 8.1L from its line up because the reliability and better Hp/Torq/Mpg of the 6.0L. These motors are so strong they are effecting ever form of Motorsports that they are allowed in.

I still think when it is time for my HP500EFI motors to be rebuilt I will look at the cost of the LS motors.

Even if I get the same power dropping 600 or more pounds out of the back of my 7200 pound boat would have to make a huge differance.