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| GM 3.6 experts... Why the disparity between different LFX engines? (Page 5/7) |
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mender
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SEP 08, 03:08 PM
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From my research (GM part numbers) the LFX cams are all the same. Intake manifold port shapes are different for RWD and FWD engines as are the head intake ports to match the manifold and probably account for about half the power difference. As mentioned earlier, the air filter/intake and exhaust system differences between the cars probably account for the rest.
You can see the Camaro vs Impala port shape here:
Some good info on the Impala LFX and mods here:
http://www.impalaforums.com...las-from-jacfab.html
Another one:
http://www.camaro5.com/foru...rumdisplay.php?f=148[This message has been edited by mender (edited 09-08-2016).]
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Raydar
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SEP 08, 06:57 PM
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Thank you for that info! I appreciate it hugely!
I also posted in the other "hi feature" thread. As I start actually doing stuff, I'll start a new thread. I'll share everything I learn. But you're way ahead of me, at this point. I suspect it will stay that way.
FWIW, the Impala guys have "discovered" an aftermarket intake manifold that seems to be worth some power. I forget who makes it, though.
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mender
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SEP 08, 09:17 PM
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Do you have a link or more info on the intake?
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Raydar
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SEP 08, 09:48 PM
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This is it. In retrospect, you've already probably seen it...
http://www.impalaforums.com...-for-lfx-impala.html
It appears that Overkill is doing the intake. I think you mentioned he was doing your tune. He probably offers a "package" of both, that are designed to work together. I think you alluded to that in your other thread.
It would be interesting to hear how much power he expects, using the whole package, with a good free-flowing exhaust.
Edit - I just went to Overkill's website. No pictures are posted. Makes me wonder if it even exists, yet. (Not to hurl stones. I didn't look terribly hard. Lots of stuff going on, here, just now.)[This message has been edited by Raydar (edited 09-08-2016).]
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mender
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SEP 08, 09:59 PM
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Overkill is selling the Jacfab intake and spacer. It's a stock Impala LFX intake that has been filled and ported, makes about 11 more hp and 15 ft lbs. I did the same mods to my intake. 
So far the highest output by an LFX Camaro manual is 317 RWHP and 247 ft.lbs on E85, 80 mm throttle body, etc, etc.[This message has been edited by mender (edited 09-08-2016).]
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Raydar
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SEP 09, 10:08 AM
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| quote | Originally posted by mender:
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So far the highest output by an LFX Camaro manual is 317 RWHP and 247 ft.lbs on E85, 80 mm throttle body, etc, etc.
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So that's... 355 at the crank? (10% loss?) And they're rated at 320, out of the box? Not bad.
Wonder what the Impala version is capable of. Do any of the FWD versions have the "big" port heads?
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dobey
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SEP 09, 10:21 AM
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| quote | Originally posted by Raydar:
So that's... 355 at the crank? (10% loss?) And they're rated at 320, out of the box? Not bad.
Wonder what the Impala version is capable of. Do any of the FWD versions have the "big" port heads? |
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I'd expect a fair bit more than 10% loss in a Camaro, even if it's a manual. If it's an auto, even more loss. At ~17% loss that's about 382 HP at the crank. But look at the torque number though. 247 lbs-ft, or about 298 at the crank with 17% loss. I'd like to see the dyno graph for that, because those numbers don't really add up, given what the stock/tuned LFX makes, and where it makes it. Both peak torque and peak HP would need to be at about 6800 RPM for those numbers to match. That must be a really flat torque curve.
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mender
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SEP 09, 03:03 PM
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That was on E85, and typically a high compression engine will make a bit under 10% more power on alcohol. Here's an earlier dyno run from the same car (automatic car), about halfway down the page:
http://www.camaro5.com/foru...php?t=233394&page=36
Pretty stout, 302 hp @6760 rpm and 267 ft.lbs @ 4850 rpm
HIs later test was with a better tune and bigger TB so I mostly believe the 317 hp but the 247 ft.lbs seems quite a bit off, should probably be more like 280 to make sense. I questioned it too but didn't get any response. The owner has been talking about a return to the dyno so maybe the next numbers will work out.[This message has been edited by mender (edited 09-09-2016).]
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dobey
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SEP 09, 03:46 PM
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| quote | Originally posted by mender:
That was on E85, and typically a high compression engine will make a bit under 10% more power on alcohol. Here's an earlier dyno run from the same car (automatic car), about halfway down the page:
http://www.camaro5.com/foru...php?t=233394&page=36
Pretty stout, 302 hp @6760 rpm and 267 ft.lbs @ 4850 rpm
HIs later test was with a better tune and bigger TB so I mostly believe the 317 hp but the 247 ft.lbs seems quite a bit off, should probably be more like 280 to make sense. I questioned it too but didn't get any response. The owner has been talking about a return to the dyno so maybe the next numbers will work out.
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10% would be around 360 at the crank. According to those numbers, it gained 100 HP at the crank. The 247 lbs-ft makes sense if it's at the same RPM as the 317, and that is 6760, but it definitely doesn't make sense as the peak. If the heads, intake, and throttle are ported/polished, then I could maybe see the 100 HP bump at that RPM, but the peak number must be something else, and down around 5000 RPM, if it's stock cams with stock cam timing for the VVT.
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mender
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SEP 09, 11:49 PM
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He had other mods as well, not just the E85 tune and big TB. Here's the first page of the dyno thread, lists the numbers and mods:
http://www.camaro5.com/foru...wthread.php?t=233394
Some auto cars are almost 280 hp, so 10% more is 308 hp, right where his earlier test was and before the 80mm TB.[This message has been edited by mender (edited 09-09-2016).]
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