Stock LSX376-B15, anyway to increase compression ratio
 

Hey guys,

I have been reseaching a somewhat affordable way to up the power in my 2010 camaro. Working on the fuel system upgrades now and will be pretty much ready for the final engine upgrade.

I have been looking really hard at the new LSX376-B15 long block but the only thing that is really scaring me away from this is the 9:1 compression. My car is a 100% street car, no strip time at all so street manners are far more important to me then very top end power. I have been told that the 9:1 compression will result in a very sluggish feel when out of boost. Having been driving my L99 with the Maggie for a while, I love the instant grunt with that combo but the L99 has the higher 10.4:1 compression which makes it feel very stout on the street even out of boost.

Back to the LSX376-B15 long block, is there anyway to raise the compression ratio near 10:1 without replacing the pistons, such as shaving the heads to decrease combustion chamber volume or go with thinner head gaskets.

I realize there may be issues created with valve clearance and thinner head gaskets may not be a great idea for running 12-15 lbs of boost.

Anyway, just looking for any experience, love the idea of the LSX376-B15 being relatively affordable, fully forged and capable of handling at least 15 lbs of boost. Not only that, you can get one shipped today!!! No wait.

Just looking for advice.

Thanks for your time

I was facing the same issue on my build - especially as I wanted to keep my maggie - the low compression doesn't really fit the bill for this sort of blower. That's why I'm building my engine now using a LSA block, shooting for 14-15 lbs of boost with around 10.1-10.4 of compression.

The LSA block will withstand far more power than a Maggie can deliver, is lighter and available as well ...

Sorry for not answering your question, I didn't even check the options of reducing cr on the LSX... the LSA was the obvious solution for me!

You would need to take out roughly 10cc out of the chamber to get up to 10:1, which is kind of a lot. By the time you do that, considering the labor, machining costs, new gaskets and bolts, etc you may want to consider a custom LS3 shortblock. I just quoted a gentleman looking at a 416ci ERL longblock for 12psi and it was pretty comparable to the LSX376.

You could do a forged (with nicer pistons) block from a good vendor for the same or less and not worry about this.

Isn't the LSx376 an iron block? Low compression, heavy assed block (totally unnecessary if a TVS2300 is your power adder), powdered metal connecting rods.....it just doesn't add up to me vs building an LS3 block based motor like it needs to be built for the job you're wanting to do. If the motor you have now is in good shape, it's worth quite a bit. Get you a motor built, that EXACTLY matches (no compromises) what you're trying to accomplish. It won't cost any more and you'll be much happier with the outcome.

Exactly. Look at the options from livernois/TSP. I would just call Livernois and order a nice forged ls3 setup for $5k or so, and be happy. Sell stock motor for $3500 or so.

Yes its around 100 lbs heavier then the LS3 but I was looking simply for longevity more then anything.

The LSX376-B15 is fully forged, forged pistons, forged crank. The one you are thinking of is not labeled as the LSX376-B8 designed for lower boost levels.

Just checked with one very good shop and was quoted $14K for a 416 forged long block. Now that did not include the core charge discount and this was a top of the line engine with best of the best parts used throughout. Well worth the price tag I am sure, just not sure if I could remain married if I dropped this amount of cash on an engine!!! Plus add in the added cost for very high end fuel supply system to feed it and installation cost of the engine, I would be pushing $20K very quickly and thats more then I want to spend.

Just figured that with the $7100-$7300 cost of the LSX376-B15 long block, throw on my Maggie off my current motor, drop $1000 on fuel pump upgrades and figure $2500-$3000 for complete installation of motor and I would be around $11-$12K with the ability to hit that 700-750 rwhp range safely and comfortably.........

If the LSX376-B15 had a 10:1 to 10.4:1 compression ratio, I would jump all over it but just worried how the lower comp at 9:1 will feel for street use???? And again, as mentioned, I can order one today and it will ship tomorrow.

You are correct that the cr will hurt you a ton with the maggie.We have helped build some of the highest hp maggie builds to date and will gladly take care of your build as well as taking your stock motor in trade.Give me a call and ill be glad to help you with your complete build.

Did you look into forging your ls3 that you currently have.

There are differences in forged parts. Like pointed out, the pistons are a low quality alloy compared to most forged pistons.

$14k is crazy. I paid less than that for a top of the line 427.

Doesn't that block still use powder metal rods which stock rod bolts?

Don't change the compression. We have used this engine already
And is not a slug.

I love how these Internet engineers always seem to try
To steer people away from gm crate engines... Ask real supporting vendors
These questions and you will get real answers due to real
World experiences used everyday.

I say go Lsx and never look back...

When's the last time you broke a powder metal rod?

Let me guess, the Internet said they are no good.

Proper built/tuned engines don't break rods or fail
Bearings or pistons.

Isn't there a guy on here with a Maggie blown low compression 416 that's stuck around the 600rwhp number? Isn't a forged crank a bit overkill at any hp number a Maggie is capable of? Not for a moment saying it's a bad choice. Just that I think there are better bang for the buck options out there.

Unless I read things wrong, TxSpeed has a forged long block LS3 with ported heads for around $8K. All new parts. New block, new ported heads, and your choice of custom cam. Your choice of compression ratio. You don't get a forged crank, but that isn't an issue at Maggie hp levels. If you think a forged crank is necessary, it's available for a few more bucks.

I know I'm a bit of an internet racer:D, but my TxSpeed long block will show up next week. It's an iron block, but it's also going in a truck. Maggie blown of course:happy0180:

I wouldnt be so quick to discount a crank.I have one of those LSX crate motors and a maggie,3000 miles and the crank broke :confused:

So.....your forged crank in your LSX broke?

Bummer. My stock crank works just fine after 17k miles.

Yeah...if your forged crank breaks, it's time to get a FERD PUSTANG, or just buy a horse....the horse will probably run better:nod:

That is an option I have been looking at as well. I have been flooding Ted with questions so he is probably about to block my e-mails!!! LOL

That's all I ended up doing. I've pleased with the reliability, drive ability, and performance. I'm sure Ted will take care of you. I think your biggest problem will be the blower. The Maggie Max parts are no longer available which will cap the blowers performance.

If you buy that longblock you can run more boost and still be on pump gas. Look into Padre's car he just went to some heads that lowered his compression.

I have 9:1 compression in my LSX motor, doesn't feel sluggish at all, they have great low end grunt, and they can handle lots of boost because of the compression.

I'm going the route of the lsx 376 b15....ill let you know how it is in a few weeks. BTW theyre forged powdered metal rods

I was breakin rods and blowing up ls1's when you were still driving rx7's and long before you had a shop so don't come at me like I don't know. Anyone that uses stock rod bolts on this motor with alot of power isn't very smart Anyone that recommends it is even worse. Dyno queens with low rpm's don't break parts properly built or not. Sure the motor will work with a Maggie but so would a motor with just pistons and rods and a stock crank and the stock ls3 heads. I still would want better rods on this motor and there is no way in hell I would test the rod bolts.

Never seen or heard of anyone breaking a stock crank.

Lmao. Ill stick my money were my mouth is on this one....

http://www.camaro5.com/forums/showthread.php?t=283673

It will be at the Texas mile in October and anybody
here can come visit the true potential of an LSXB-15

So your going to run 1000 Rwhp through a lsxb-15 and not do anything to it? Your going to do this with those rods/ rod bolts?

Why did Ted stop offering the Maggie upgrade kits?

So your just running forged rods and pistons, correct? What RWHP level are you running at. If I remember correctly, its not all that much considering the amazing 1/4 mile times your putting down. Your car has always been my blueprint for what I would like to do with my L99.

Ted didn't stop. The guy making the spacer just disappeared. I offered my spacer as a template but he didn't want to do it at that time.

My engine has forged pistons and rods with ARP 2000 hardware. Stock heads with Teds cam and valvetrain. Races on 104. Currently it makes 732 rwhp but once I can get traction Ill start to up that a little. At one point Id like to have 800 rwhp. My set up is far from some of the things guys are doing but it has worked for me!!

It was the LSX crank,i wasnt to happy since i bought the crate motor for peace of mind. On a side note a 9-1 motor is a 9-1 motor the block doesnt add any power :thumb: Also the company that makes the crank and rods for the LSX motors rate them at 750 flywheel,another fact i wasnt to happy with

I have a few spacers if you know of anyone that needs one.

Yeah I can also get someone a spacer, just PM me, Hendrix knows their stuff with the Maggie.

The aftermarket cranks are a pretty good deal compared to what you pay for reusing a stock crank, especially for the blower cars.

The stock crank will be light on the counterweights for a forged rod and piston combo, so it would need heavy metal installed to balance out. Not to mention that they are not keyed for a supercharger, so you would have to pay to either key it in a mill at the machine shop (which is the best way) or have it "pinned", which has it's own problems for sure.

The aftermarket cranks will have the heavy metal installed and are really close to what most forged piston and rod combos will weigh and won't even need any more heavy metal when you have it balanced. They are also already keyed all the way up the snout for the keyed balancers for supercharged cars.

In the end, you have paid almost just as much for a stock crank, and you're still down 40 cubic inches.

Even the B15 version? At that rate your better of buying a built shortblock from Texas Speed.

I'm that guy :bonk: Forged cranks are cheap compared to the cost of everything else a big build needs, so why risk it?

The B15 is a stout motor, much better than the old LSX376-B8. The B15 is made for 15 pounds of boost, so it can take a good deal of punishment. I was going to use one in my car, but I went for displacement instead.

Just as GM Did on engine Dyno at 15 psi for 24 hrs.I spoke
with them more than once at SEMA (nov 2012) about this engine
and it's rod bolts,pistons,heads,camshaft profile....etc.

They went through many different ring packs on this engine
to ensure it would do as advertised.I have plenty of confidence.

With a warranty!

Yeah that's what I remember reading and I was like that looks like a stout piece. I'm not chasing down any world records so adding another 100lbs to the nose doesn't concern me much. Looks like it would be perfect for me as 15lbs is about all my blower is gonna make + a bigger shot could be perfect. Can't beat the price either.

What I wonder is how much power I'm going to loose going to this motor with the compression ratio from a stock LS3

Maybe 40hp tops is all you're gonna lose.

I'm under the impression they were using the stock style rod bolts which would really make me nervous even more so if you plan on putting any good rpms to the engine but maybe I'm misinformed.

If your staying under a 1000 with a supercharger I wouldn't spend the money if I wanted to stay stock cubes. If I was going to buy a forged crank I would spend the money on a nice one. I've seen quite a few cheaper ones break but I've never seen a stock one break. A turbo unless you were shooting for crazy numbers or more cubes there really isn't any reason to change it out. Mighty Mouse ran mid and low 8's in his 3800 lb turbo car for years with a Erl block and a stock crank put 20k miles on it also in that time.