LM7 vs L33
10-03-2011, 04:27 PM
#1
LM7 vs L33 Reading the new Super Chevy I see they have started a new series called Modern Mouse using a LM7 5.3.
On the westec dyno with a tune and headers it produced 363HP and 385 TQ.
Pretty good numbers for a stock pickup motor with the samllest LS cam made.
Adding a 212/218 cam with .522/.529 lift it made 385/412.
Now my question is how would a L33 stack up?
It has half a point higher compression and a slightly better cam and of course it has an aluminum block.
Looking at L33s in the junkyards I see they aren't that much more than a iron block 5.3 and the aluminum block would knock 65 pounds off the front end.
I see some of the super fast turbo cars use L33s so I know they are really stout.
So about how much more will the L33 produce compared to a LM7?
Thanks
Jarhead
On the westec dyno with a tune and headers it produced 363HP and 385 TQ.
Pretty good numbers for a stock pickup motor with the samllest LS cam made.
Adding a 212/218 cam with .522/.529 lift it made 385/412.
Now my question is how would a L33 stack up?
It has half a point higher compression and a slightly better cam and of course it has an aluminum block.
Looking at L33s in the junkyards I see they aren't that much more than a iron block 5.3 and the aluminum block would knock 65 pounds off the front end.
I see some of the super fast turbo cars use L33s so I know they are really stout.
So about how much more will the L33 produce compared to a LM7?
Thanks
Jarhead
10-04-2011, 09:38 AM
#3
The 799 heads on the L33 are THE main benefit of an L33 over a LM7. Outside of that, if you were planning forced induction, a LM7 would probably be the better way to go. Stouter iron block, a little lower compression, and they are MUCH easier to find. I don't see a lot of L33's around. But junk yards almost give away LM7 (figuretivly speaking, due to their availability and < $400 price in most cases).
Engine comparison questions always become a question of "with what modifications". With a new set of decent heads and a cam they both become pretty much the same.
Engine comparison questions always become a question of "with what modifications". With a new set of decent heads and a cam they both become pretty much the same.
10-04-2011, 12:16 PM
#4
Thanks for the info.
Looking on the various junkyard web search sites I find lots of L33s in the $1000-1500 range for 50K mile engines.
Unlike some I can't seem to find LM7s for a couple of hundred bucks, most I find are 750 and up.
I'm thinking a pretty much stock L33 for around a grand seems like a good deal to me.
More compression than an LM7, better heads, a better cam and an aluminum block to boot.
Super Chevy made the point that their stock LM7 outperformed both the 365HP 327 and the 1970 370HP LT1 SBC on the dyno.
I happened to grow up in the era of those engines, I had a number of both over the years and they hauled *** but they required premium gas(11 to 1 compression), needed plugs and points changed weekly and had slobbering cams.
Fuel mileage was miserable but premium only cost 30 cents.
Todays 5.3s idle smooth as a swiss watch, and in the era of $4 a gallon gas sip regular fuel and last 300K+ miles and only need sparkplugs ever few years.
Thanks again
Jarhead
Looking on the various junkyard web search sites I find lots of L33s in the $1000-1500 range for 50K mile engines.
Unlike some I can't seem to find LM7s for a couple of hundred bucks, most I find are 750 and up.
I'm thinking a pretty much stock L33 for around a grand seems like a good deal to me.
More compression than an LM7, better heads, a better cam and an aluminum block to boot.
Super Chevy made the point that their stock LM7 outperformed both the 365HP 327 and the 1970 370HP LT1 SBC on the dyno.
I happened to grow up in the era of those engines, I had a number of both over the years and they hauled *** but they required premium gas(11 to 1 compression), needed plugs and points changed weekly and had slobbering cams.
Fuel mileage was miserable but premium only cost 30 cents.
Todays 5.3s idle smooth as a swiss watch, and in the era of $4 a gallon gas sip regular fuel and last 300K+ miles and only need sparkplugs ever few years.
Thanks again
Jarhead
