PDA

View Full Version : A few modern engine offering questions


duckguy
12-26-2010, 06:17 PM
Indmar LY6 6.0
Indmar Hammerhead 383
PCM ZZ409

What are these motors true hp/torque numbers? The ly6 is a 6.0 vs the hammerhead is a 6.2 so it should put out a little more? The PCM claims 409 hp and almost 500 ft lb. with there 1:23 trans. I cant imagine a huge difference between these two mfg.. do is an ly6 with that trans putting out that kind of torque too?

1redTA
12-26-2010, 08:22 PM
I believe GM rates the 6.0 at 385hp in automobiles

DooSPX
12-26-2010, 09:02 PM
GM rated the THEIR marine version of the LY6 at 385hp, the Trucks LY6 is only 353hp.

But I will say this, Indmar, PCM and the like does not always take a motor straight from Ford/GM, etc and put marine parts on it and send it out in boats. They do sometimes add performance camshafts and sometimes custom intake manifolds to bring the power curve where they want it. MCX is a prime example of the custom manifold. Also, the new ETX exhaust manifolds are like adding headers too... Far better than what used to be used in marine engines and better than automotive exhaust manifolds as well.

Eagle Lake Rebel
12-27-2010, 12:32 AM
I don't buy any 6.0ish size motor is pumping out 500ft/lbs of torque. I've got an LY6 and frequently drive another MC with an 8.1L which l think is rated around the 500ft/lb range and there is a big difference on how the engine pulls. We both have the same tranny ratio & both boats are proped down for pulling.

DooSPX
12-27-2010, 01:46 PM
I agree about the PCM 409...
Unless PCM put a supercharger on it, which I doubt... It is not listed and they state the engine can run on 87 oct. fuel.
BTW, the PCM ZR409 is rated through the 1:1 trans per PCM.
Another thing I noticed is PCM says the 409 is a 6.0L /366cid. a GM 6.0L is 364cid. so either they miss-quoted or they did a slight over bore on the cylinders.
the 409 hp is easy to see, but the 492lbft trq might be a stretch...
They installed a custom spec camshaft, 409HP through the tranny is easy with the LY6 6.0L with a custom cam, the L92 heads on the LY6 make KILLER power. The rated 492lbft seems a little high, but a good bit over 400 is easy as pie with the LY6 and a cam. its very common to see L92 headed 6.0L make 430hp/415trq to the ground with a very mild cam in cars.


ELR, the 8.1L makes all its power/torque much lower in curve then the 6.0L no matter the rated HP/TRQ. It will feel MUCH stronger out of the hole and throttle response.

1redTA
12-27-2010, 02:21 PM
GM rated the THEIR marine version of the LY6 at 385hp, the Trucks LY6 is only 353hp.

whoops, maybe I'm thinking of the Cadillac HO 6.0 has 385

isn't the 8.1 a 496 cubic inch engine? One horse power per cubic inch is very easy to attain in NA applications. I don't think 500ft/lbs would be to difficult for that engine

DooSPX
12-27-2010, 02:59 PM
whoops, maybe I'm thinking of the Cadillac HO 6.0 has 385

isn't the 8.1 a 496 cubic inch engine? One horse power per cubic inch is very easy to attain in NA applications. I don't think 500ft/lbs would be to difficult for that engine

Which year Caddy you thinking of? the LQ9 6.0L 364cid found in the 03-06 Denali, Silveraldo SS and Caddy was 345HP 385TRQ. The 07+ Caddy's, etc is the L92 6.2L 376cid is rated at 403HP 417TRQ.

Yes, the Vortec 8100 8.1 was 496cid, but ELP was referring to the 6.0L ZR409 from PCM who claims 492lb ft.

EDIT: I also want to add that the Indmar 383 should not be in the group because it is a different Generation of GM Small Blocks compared to the LY6 and ZR409. The HammerHead 383 is a GenI stroked 5.7L SBC to get 383cid w/ EFI and GM Fast Burn heads. The other two listed are GenIV... WAY ahead of the GenII stuff. The only thing the have in common are they are both GM based SBC

east tx skier
12-27-2010, 03:56 PM
I agree about the PCM 409...
Unless PCM put a supercharger on it, which I doubt... It is not listed and they state the engine can run on 87 oct. fuel.
BTW, the PCM ZR409 is rated through the 1:1 trans per PCM.
Another thing I noticed is PCM says the 409 is a 6.0L /366cid. a GM 6.0L is 364cid. so either they miss-quoted or they did a slight over bore on the cylinders.
the 409 hp is easy to see, but the 492lbft trq might be a stretch...
They installed a custom spec camshaft, 409HP through the tranny is easy with the LY6 6.0L with a custom cam, the L92 heads on the LY6 make KILLER power. The rated 492lbft seems a little high, but a good bit over 400 is easy as pie with the LY6 and a cam. its very common to see L92 headed 6.0L make 430hp/415trq to the ground with a very mild cam in cars.


ELR, the 8.1L makes all its power/torque much lower in curve then the 6.0L no matter the rated HP/TRQ. It will feel MUCH stronger out of the hole and throttle response.

From what I have read, and this should be taken with as much of a grain of salt as anything you see on the internet, PCM actually tends to underrate their engine specs, at least in the hp area.

The horsepower of all of these engines seemed to go up a bit when they shifted to the econtrols ecm in 2008 or so.

DooSPX
12-27-2010, 05:22 PM
My guess is they have a custom intake manifold and a very thought out custom camshaft. The cam to make those kind of numbers probably has high lift and modest duration with spot on valve events.
a 6.0L w/ L92 heads, good cam and good intake with good tuning (where their new ECM comes into play) can easily make 450+hp but for the torque to be that much higher than the HP would suggest that they used a custom cam with a lot of lift and a good amount of valve overlap at TDC and most likely a very tight LSA too. I doubt that because they claim its a super smooth idle and not a peaky power curve, which is contradicting to that cam setup.
My guess would be they do like magazines and TV shows and dyno the engines, take the best peak power from all their dyno testing, never use correction factors and post them.
If they indeed get that the torque to be almost 90 more than the hp number, I would love to know the camshaft/intake specs used.

Eagle Lake Rebel
12-27-2010, 08:28 PM
Another bud of mine has one of those Te' boats with the 400hp PCM.... didn't feel any stronger than the LY in any area. He has reproped also, throttle control stinks, but that may not be PCM's problem. I think both engines put up around 400hp with 400ft/lbs of torque. Want more find an 8.1L or something with a blower on it.

Forrest-X45
12-29-2010, 01:41 AM
Indmar rated the LY6 at 400HP and 420 to 425TQ.
They rated the L18 at 450HP and 520TQ.

The 95 foot pounds of torque makes a world of difference........wish I had one. :)