I'm not ready to announce just yet how I happened to acquire this profoundly important piece of technical knowledge, but . . .
those of you contemplating engine transplants (not necessarily in an SSR), the LS engine series can be pretty confusing, and it is easy for even a pro to make a significant error. Be careful!!
Quick and highly superficial review of some (not all) of these engines:
LS1 5.7 liter all aluminum (block AND heads), hi-performance heads, 300 to 350 crank hp depending on year & RPO
LS6 5.7 liter all aluminum (block AND heads), higher-performance heads & compression, 385 to 405 crank hp depending on year and RPO
LR4 4.8 liter cast iron block truck engine 270 to 295 crank hp
LM7 5.3 liter cast iron block truck engine, 290 crank hp or so
LM4 5.3 all alloy truck engine (used in 03/04 SSR, Trailblazer, and Envoy). 100 lb lighter than all iron LS engines, and 65 lb lighter than iron block / alloy head LS engines, but still "truck" heads in terms of flow potential (but astonishingly good when used with right cam - up to 6800 rpm!!)
L33 5.3 liter all alloy (similar to LM4) but configured for and used in extended cab pickups only
L59 5.3 liter - flexible fuel vesion of LM7
LQ4 6.0 liter cast iron block, alloy hi performance heads truck & SUV engine, 300 to 325 crank hp
LQ9 6.0 liter cast iron block, alloy hi performance heads, 345 crank hp
LS2 6.0 liter all alloy, high performance heads, 400 crank hp
Confusing, isn't it?
It gets worse.
For example, and ONLY for example, the LQ4, LQ9, and LS2 all look similar, right? Why the difference in power output? Glad you asked. Turns out that tere are subtle and not subtle differences that make a big difference - but can also be eliminated via equivalent hopping-up efforts.
All have the same bore, stroke, and crank.
Rods may or may not be identical - GM is not saying, and no one that I know has the access to, and the knoweldge and equipment, to analyze the rods
Pistons differ. The LQ4 piston is a dished design, cast piston. The purpose of the dish is to reduce compression to 9.4. The LQ9 has a flat top piston, for higher compression (10.08), but it is also higher quality. It's also coated with a heat rejection cotasing top and sides. The LS2 has a lighter weight flat top piston (since it needs to rev much higher).
The cam in the LQ4 and LQ9 is identical, and very conservative (196 In / 207 Ex / 0.467/0.479 lift) - similar to the LM4 and LM7 cams in fact. The cam in the LS2 is the one out of the 2001 (not 2002!) LS6, and is more like 204 In / 211 Ex / 0.525 lift. This results in more rpm at peak power (6250 or so versus 5200) and more power.
The heads in the LQ4 and LQ( started out as different but then standardized on the better of the two. This head is identical to the LS6 = LS2 head, except that it has a larger combustion chamber for lower compression ratio. The combination of larger chamber and dished psirton holds the LQ4 to 9.4. The combination of the same chamber but flat piston gives the LQ9 10.08 to 1 compression. The use of a smaller chamber (64cc versus 71) hikes the LS2 compression ratio to 10.9!
So, the LQ4 makes the least power (300 to 325 hp depending on RPO). The LQ9, with its higher compression and slightly different tune makes 345 hp. The LS2 with its smaller chambers and more aggressive cam makes 400 hp.
Here;s the interesting part on thse 3 engines: The LS2 is costly because the uneducated hotrodders only know that a "Corvette" engine is HOT, and supply and demand takes it from there. (Same way that an LS1 from a Camaro gets $2500 at salvage yards, but an LM7 gets under $1000).
The LQ4 is cheap because no one outside the techies understands that it is incredibly similar to an LS2 except for cam (easily changed) and lower compression (still good, and IDEAL for supercharging), and that the low tech pistons are routinely spun to 6500 to 6800 rpm in magazine buildup projects.
The LQ9 is costlier than the LQ4, because even the technically uneducated know that 345 hp is better than 325, and the cost of ADDING horsepower is statistically about $60 to $75 per crank hp, so that 20 hp is worth $1200 to $1500 if you leave the engine unmodified. If you do modify it via a freer breathing cam, the higher compression and better pistons are still a better starting point. If you take the recipes in the magazine articles, and add better pistons and higher compression, it only gets better.
By the way, the smaller chamber heads from the LS2 are a straight bolt-on to the LQ4 OR LQ9. With the LQ9, you get 10.9 compression that way, same as the LS2. On the LQ4, you get around 10.5.
The same aftermarket, or GM Performance Parts cams, will work on all 3 engines, with the differences in outcome being a result of the different compression ratio (not a huge difference). The pistons on the LS2 being a bit lighter supposedly, will be less stressed at really high rpm, and will put less stress on the vulnerable connecting rod bolts, that when they fail, fail because of inertia loading.
The cast iron blocks of the LQ4 and LQ9 are acknowledged to be both stronger, and also much more easily and cheaply overbored. They can be bored out 0.030" without fanfare, whereas the LS2 with its sleeved bores can only be bored out 0.010, and beyond that requires re-sleeving ($$$). But, the LS2 is lighter by 65 pounds because of that alloy block.
Any of these 3 engines can be pumped to clsoe to 500 crank horsepower while retaining civility and reliability, and to more than that if civility and reliability need not be "perfect".
Here's another neat tidibit: any of the 3 can be stripped off their fuel injection and fed via carburetor, and NOT LOSE POWER, although civility and fuel mileage will lieklysuffer. But the dyno results from multiple independent parties are very clear: the carbs meet, or exceed, the power curves of the EFI.
For you guys with emissions requirements, that is a moot point. But for "Red" on my SLURP project, it is not.
I started by saying "don't confuse these LS variaitons". I meant it. Today, a PRO at one of the country's largest salvage operations was shown to have sent out an LQ4 in place of an LQ9 because he was unaware that there WERE two variations of a 6.0 liter "truck and SUV" engine. He had to correct the error, and did so graciously, but it cost him some money.
Be very careful in analyzing LS engine specs. Theya re NOT obvious, even to the pros. I suspect I may have made some errors even in this quick and dirty summary. If so, those who know better, please feel free to correct me. We want accurate info on this site.
Jim G
Last edited by JimGnitecki : 02-12-2008 at 07:00 PM.
Hi Jim
The Rods Are The Same As Replacment Rods Have The Same Part # 12577583 Exept 04 Lq4 1st Design Has A Fixed Pin #12568734 As The Rest Have Floating Pins Also The Same Rods For The 5.3 L59 And Lm7
LQ9 04 FIRST DESIGN #88894241 HAS A UPPER COMPRESSION IS 1.5MM THICK FOR 1ST DESIGN
LQ9 04-07 & LS2 04-05 SECOND DESIGN #89017478 HAS A UPPER COMP RING THAT IS 1.2MM THICK WITOUT 4 DRAINHOLES AT 3RD RING LAND
LS6 04-05 89017581
IF YOU WANT MORE ILL HAVE TO FINISH WED AS ITS TIME TO GO HOME
Oh, wow. RRSSRTOY. This seems to say that the 2nd edition 2004 (in GM talk that means 2nd design released that year), and all subsequent LQ9 and LS2 pistons are identical.
Since we already know that the cranks and rods are identical, this basically says that an LS2 and a later model LQ9 are identical engines except for:
- LQ9 has lower compression ratio due to larger chambers
- LQ9 is cast iron block versus alloy block
- LQ9 stock cam is much milder than the LS2 stock cam
Notice I said "stock" cam.
IF someone is contemplating changing cams anyway (and what redblooded American would NOT be contemplating that), it makes sense to buy the much less costly, and much more available, LQ9 as the base for the cam swap!
With an LS engine that is not yet inside a vehicle, the cam swap is remarkably easy and quick.
Then, how hard is it to remove that complex, "structural" oil pan and change the connecting rod bolts to ARP bolts? IF there are no subtle glitches there to be avoided, changing those con rod bolts takes out the ONLY weaker link in the entire engine. 6800 rpm is very feasible then. People have been doing 6800 rpm on the dyno with this engine, but have been hesitant about keeping that sort of rev limit on the street. The ARP connecting rod bolts change that.
We are talking about a LOT of power in this scenario.
The LS2 and LQ9 hads are identical except for chamber volume.
Ls2 owners who are running one of 2005SSR6speed's Magnuson kits, and want a little less compression to help deter detonation at higher boost levels, could potentially trade heads with someone who is building a naturally aspirated LQ9. The SSR owner gets the lower compression ratio he/she is seeking with the supercharger. The LQ9 owner gets a bit more compression and therefore a bit more power in the naturally aspirated build.
A big thing to note is that the stock Valvetrain is realistically at it limits at 6600 rpm's. Once you upgrade the valve springs then the limit is still there for the Hydraulic Roller Lifters. You can spin them up to 7000 rpm's but realistically wont see much more then 6800 because it will start to float.
I have spoken with a few big names in the LSX engines and a 4" bore short stroke engine would be a perfect high RPM engine. If you use a Solid Roller Cam and Lifters and a Rev Kit then the rpm would last out to about 8000-8500 rpm's.
Hate to spoil it for you Jim, but changing connecting rod bolts is not as simple a deal as you would think. The bolt centers the rod cap as well as holding it in place. After changing bolts, the rods need to be machined to assure that the "hole" is still round and the side surfaces are aligned properly. Because material is removed during this process they also need to be re-balanced for use in a high-performance engine.
After buying the bolts and having the machine work done your investment will be very close to the cost of a set of the less-expensive aftermarket rods in most cases.
__________________
2005 Slingshot Yellow 1SB No 16549 - 12.59 et @ 107.35
2000 Silverado 5.3 Step-Side PU - Daily Driver
1957 Chevy BelAir Street Rod - 10.65 et
Hate to spoil it for you Jim, but changing connecting rod bolts is not as simple a deal as you would think. The bolt centers the rod cap as well as holding it in place. After changing bolts, the rods need to be machined to assure that the "hole" is still round and the side surfaces are aligned properly. Because material is removed during this process they also need to be re-balanced for use in a high-performance engine.
After buying the bolts and having the machine work done your investment will be very close to the cost of a set of the less-expensive aftermarket rods in most cases.
Ouch! Back to the drawing board on that one aspect.
Jim, im the guy who posed the car craft article about the 5.3 .Check out Hot rod magazine site , they have a series on the big mootor & had been dyno testing different heads , intakes & such, then went to power adders, later in the series. I think it might help you in your research.
Funny i had ignored both theos mags for decaes until I got a chepo subscription, I cant believe th wealth of info in those pubs lately & on there web site. Seem they went back to their roots.
Jim, im the guy who posed the car craft article about the 5.3 .Check out Hot rod magazine site , they have a series on the big mootor & had been dyno testing different heads , intakes & such, then went to power adders, later in the series. I think it might help you in your research.
Funny i had ignored both theos mags for decaes until I got a chepo subscription, I cant believe th wealth of info in those pubs lately & on there web site. Seem they went back to their roots.
Peter m
Peter: I agree about the mags becoming much better lately! You still have to look very carefully at some of the articles to check for bad assumptions or tricky omissions, but they HAVE been a lot more useful lately! Thanks for drawing our attention to them here on the board. Good stuff there for thopse willing to analyze it.
You DO have to be very careful with some of them. For example, that "Hot Rod Engines" (Spring 2008) has what COULD have been a really good article documenting work that Ken Duttweiler did on the 6.0 liter, BUT the organizational logic and presentation were so amateur hour that it was laughable and also impossible to follow properly.
As one simple example of the the kind of foolishness in that article, the Power table, which purported to compare the power achieved, by rpm, for each of the 8 combinations tried, actually STOPPED at 5600 rpm - 1300 rpm BEFORE their top killer combination, the carbureted setup, made its power!! So, if you looked at the damn table and compared power produced, you would MISS it entirely!!
The torque was displayed for all the combos as a graph that DID go to 6900, but because it was torque versus horsepower, the torque reading for that carb combo was "low" by 6900 rpm, BUT still high enough, because of the ultra high rpm, to be the TOP number for power produced. Since most people don't do the torque versus power math in their heads, they would NOT see that. In afct, the ONLY way you could see it is if you read the text a page later VERY closely.
It's this kind of crap that makes me wonder who writes these darn articles. This is also just the latest in a string of Duttweiler screwups too. Either he works with really bad writers who don't really understand what they are documenting, or he himself is sloppy. Neither is good for his reputation.
I just bought that engine issue & was wondering the same thing.
keep up the good work.
I have been road racing for the last 20 years, but got pretty sick this past year. thankfully I am recovering ,but slowly so I have been looking to drag racing to keep my foot in the hobby, hence my sudden postings, but ive been lurking for a while...
Good job guys I just finished building a 350 chevy motor, installed 400 crank, nice cam 64cc heads with dished pistons, roller lifters, and rockers. ofcourse bored to .060 over. I hope to get 415 hp or better on pump gas at about 9.1 or better compression. I spent as much on the billet dress up parts as I did on the parts and machine work. I did hog out the top of the heads to accomodate larger honey combed Valve Springs to help aleviate early valve float. I am installing this build into a 1940 Pickup with a 700R4. She ought to be fun.
Frank Henson PS I was going to mention the make of the Truck> But its the F-Word and some guys can't handle it.
Last edited by MoodyBlue : 02-18-2008 at 04:29 PM.
Reason: F word
Frank Henson PS I was going to mention the make of the Truck> But its the F-Word and some guys can't handle it.
We have been trying to stretch people's tolerance on this forum lately, so the Fo_d -word won't be nearly as explosive in its impact, and won't have you tarred and feathered off the forum.
Where are you located?
Those 1940 models from all the manufacturers were SO distinctly "art deco" in their styling. It really makes them stand out in a crowd. I am pretty much a pushover for any of the 1940 through 1955 models, and like many of the 1930s models as well.
We have been trying to stretch people's tolerance on this forum lately, so the Fo_d -word won't be nearly as explosive in its impact, and won't have you tarred and feathered off the forum.
Where are you located?
Those 1940 models from all the manufacturers were SO distinctly "art deco" in their styling. It really makes them stand out in a crowd. I am pretty much a pushover for any of the 1940 through 1955 models, and like many of the 1930s models as well.
This is "green recycling" at its best.
Jim G
I am located in Bakersfield CA. I have a 1940-41 and 42 Ford, All Pickups. I just boxed in the frame and installed a Mustang IFS and a IRS. on the 1940, Well the rear is a T-Bird 8.8 not mustang. I got the rear end from a supercharged T-Bird 1998, If you have never seen one of these rear ends. You will be impressed at how easy they are to remove and install
into almost any vehicle. Check one out for yourself but don't tell anyone. That way we will have them all to ourselves. But now on a serious side. The Western Street Rod Nationals are held here in late April. If you get a chance, if not here, go to one near your area. There is generally close to 2000 Hot Rods here every year.
I got the rear end from a supercharged T-Bird 1998, If you have never seen one of these rear ends. You will be impressed at how easy they are to remove and install
into almost any vehicle. Check one out for yourself but don't tell anyone. That way we will have them all to ourselves.
Frank Henson
That sounds like a neat tip! No one has ever mentioned these to me. I need to look into this! What is the width of one (without cutting)?
That sounds like a neat tip! No one has ever mentioned these to me. I need to look into this! What is the width of one (without cutting)?
Jim G
The T-Bird IRS is a complete System in a box frame. Ther are four bolts that hold it into place.
There are more bolts ofcourse for shock mounting and a couple of bolts more on the T-Bird frame that is used to stabalize the forward torque to the axles. But if you are looking for an easy install on a project vehicle this is a good way to go.
The T-Bird IRS is a complete System in a box frame. Ther are four bolts that hold it into place.
There are more bolts ofcourse for shock mounting and a couple of bolts more on the T-Bird frame that is used to stabalize the forward torque to the axles. But if you are looking for an easy install on a project vehicle this is a good way to go.
Rear tread (tire centerline to tire centerline) in the 1955 Chevy 3100 model pickup is 61.02 inches.
62" rotor to rotor would probably be close, right? Without cutting and restraightening even . . .
hmmmmmm
Any idea of WEIGHT of the complete assemlby without wheels and tires?
Jim G
I did not weight it. it takes two strong guys to carry it. I will give it a SWAG at 300# + or - a few pounds. Its a tough unit but it can be trimed to lessen the weight. One other thing I did not mention, the bolt pattern is 5 on 4 1/4 most fords are 5 on 4 1/2 so you need to change out the hubs or take them to the Machine shop. No one makes a universal wheel lug pattern as of yet too fit both. It's not that much trouble to make them match.
Hi Jim. Do you have any info on I.D. numbers that can be used to identify a 5.3L from a 6.0L from the outside? I'm used to working with head and block casting numbers with Corvettes etc. from the 60's, but I realize that the alluminum blocks and heads were manufactured using a differenct process. I see some numbers etched into the heads (need to look closer at the block today).
The reason I ask is that one of my contacts in GM tells me that records indicate that my '03 had a LS2 dropped in it prior to being but into service in NASCAR events in 2005. I'm trying to visually check this out to confirm. Thanks in advance.
My SSR: "Slingshot Yellow" 05 auto License plate "BIG V8"
Quick and easy way to tell
Look at the throttle body, the 6.0 is different from the 5.3 look at engine pictures in the gallery to see the difference. This method is not fool proof but its quick and works pretty well
Look at the throttle body, the 6.0 is different from the 5.3 look at engine pictures in the gallery to see the difference. This method is not fool proof but its quick and works pretty well
Thanks for the tip poppa. Based on the throttle body it looks like it's the 5.3L. My contact is going to do some more digging--we'll see what he finds out.
The throttle body on the 5.3 has THREE bolts securing it to the intake, while the throttle body on the LS2 6.0 liter has FOUR bolts.
The intake manifold itself is also notably physically higher in height than the one on the LS2. The one on the 5.3 is the "truck" manifold, designed for low and mid range torque, while the LS2 intake favors higher rpm at the expense of lower rpm.
The vehicle (not just engine, but vehicle) wiring bus on the 05/06 SSRs that came with the 6.0 liter LS2 is completely different than the one on the 03/04 SSRs that came with the 5.3 liter. It would have been impossible to change engines without changing the entire vehicle wiring harness, and the sensors that communciate with it, which is a BIG job that I am sure GM would NOT have undertaken. It would have been far easier to start with a new vehicle.
Finally, changing the engine to a different emissions certification year would be illegal, and so again, I'm sure GM would not have done that.
Thanks Jim. Three bolts so it's definitely a 5.3L. I'll be talking to my GM contact again next week--it's easy to confuse trucks as an '05 painted just like mine was also used in NASCAR during the '05 and '06 seasons (it too sold at Barrett-Jackson last month).
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