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Stefan (Forum Supporter)
Stefan (Forum Supporter) MegaDork
7/28/20 1:03 p.m.
GIRTHQUAKE said:

Oh god there's so much info to go through

NickD said:
Curtis73 (Forum Supporter) said:

Factory intakes are pretty good.  LS1 intakes are kinda unspecial.  LS6 intakes will pretty easily support 500 hp.  Truck intakes are actually quite good, but they are tall and ugly

Trailblazer SS intake is also amazing but hard to find. And the LS2 intake manifold is garbage.

The *real* reason I speak of the LS6 intake is because of the low hood line of the 928- doubt the SS intake will fit. Plus, i'd probably use that intake with a turbo if I had one instead.

Thanks for the link Stefan; I'm not sure what the max on the Porsche transaxle can take, but I DO know people have ran them up to five-hundo without much problem.

928 International campaigned one at about 425+bhp in IMSA competition:

http://www.928intl.com/race/index.htm

With some further development, including a CF intake, it was up to 485bhp:

 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
7/28/20 1:16 p.m.
Paul_VR6 (Forum Supporter) said:

After tuning lots of engines, 11:1 is a good practical limit for pump gas. It's dependent on the cam choice (IVC mostly) so you can go up a little bit with later valve closings, but down for under 93 octane. If it's flex fuel and you plan to tune it you can easily bump to 12-12.5:1 if you want to use E85 most of the time and only want it to limp along on lower octane if stuck without good fuel. 

While I agree somewhat, that is only in a very narrow field of modern EFI engines.  If you insert Ford Flathead in there, you would have to say more like 7.5:1.  Old school Hemi, maybe 9:1.  BBC, 10:1 unless you go really hairy with cam duration.

yupididit
yupididit UberDork
7/28/20 1:43 p.m.
NickD said:
Curtis73 (Forum Supporter) said:

Factory intakes are pretty good.  LS1 intakes are kinda unspecial.  LS6 intakes will pretty easily support 500 hp.  Truck intakes are actually quite good, but they are tall and ugly

Trailblazer SS intake is also amazing but hard to find. And the LS2 intake manifold is garbage.

Why is the LS2 intake manifold garb?

yupididit
yupididit UberDork
7/28/20 1:43 p.m.
Stampie (FS) said:
yupididit said:

Ah okay. Looking for an intake they'll clear the hood of an xjs lol

How you gonna make an LS intake work on that awesome powerful V12?

By removing the v12 that's likely going to a fellow GRM member devil

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
7/28/20 1:46 p.m.
yupididit said:

In reply to Pete. (l33t FS) :

Shredding gears at ONLY 700hp? That isn't strong these days? 

Relative to how much power you can trip, fall, and accidentally make with an LS, yeah.  The torque is the key, of course, and I don't recall how much torque he was making.

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) Dork
7/29/20 7:50 a.m.
Curtis73 (Forum Supporter) said:
Paul_VR6 (Forum Supporter) said:

After tuning lots of engines, 11:1 is a good practical limit for pump gas. It's dependent on the cam choice (IVC mostly) so you can go up a little bit with later valve closings, but down for under 93 octane. If it's flex fuel and you plan to tune it you can easily bump to 12-12.5:1 if you want to use E85 most of the time and only want it to limp along on lower octane if stuck without good fuel. 

While I agree somewhat, that is only in a very narrow field of modern EFI engines.  If you insert Ford Flathead in there, you would have to say more like 7.5:1.  Old school Hemi, maybe 9:1.  BBC, 10:1 unless you go really hairy with cam duration.

I completely agree with your caveat! 

z31maniac
z31maniac MegaDork
7/29/20 8:00 a.m.
Paul_VR6 (Forum Supporter) said:

After tuning lots of engines, 11:1 is a good practical limit for pump gas. It's dependent on the cam choice (IVC mostly) so you can go up a little bit with later valve closings, but down for under 93 octane. If it's flex fuel and you plan to tune it you can easily bump to 12-12.5:1 if you want to use E85 most of the time and only want it to limp along on lower octane if stuck without good fuel. 

Are you talking about the big bore of an LS, or just engines in general? 

Gen III Coyote's are 12:1, the BRZ/GT86 ships with a 12.5:1 engine and the ND 13:1. And all are capable of low-boost, forced induction setups on pump gas with proper tuning. 

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) Dork
7/29/20 10:12 a.m.

Bore has some to do, smaller bore you can get away with some more but it's not a huge change. Assumption was port EFI, not GDI as well, as that is a whole other operating scheme that seemed a bit further off the OP than I was thinking about. VVT (or lack thereof) is also a consideration as well.

NOHOME
NOHOME MegaDork
7/29/20 10:34 a.m.

In reply to GIRTHQUAKE :

like a medicated prairie dog in a manure pile.

I have not mentally made it past this phrase so as to address anything else in your post. Do carry on.

z31maniac
z31maniac MegaDork
7/29/20 11:13 a.m.
Paul_VR6 (Forum Supporter) said:

Bore has some to do, smaller bore you can get away with some more but it's not a huge change. Assumption was port EFI, not GDI as well, as that is a whole other operating scheme that seemed a bit further off the OP than I was thinking about. VVT (or lack thereof) is also a consideration as well.

That's a good point on port vs DI

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) Dork
7/29/20 12:43 p.m.

There is an almost infinite amount of nuance that can be applied and in the end you still need to choose and live with it.

yupididit
yupididit UberDork
7/29/20 1:04 p.m.

Next 6 pages of this thread will be about boosting GDI engines vs port EFI and the downsides to both. 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
7/29/20 1:19 p.m.

berkeleying truth.  We have an amazing talent for that.

GrassrootsFlounderSports.

Maybe the mods can make a subforum and move threads there when they get off topic.

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) Dork
7/29/20 1:49 p.m.
yupididit said:

Next 6 pages of this thread will be about boosting GDI engines vs port EFI and the downsides to both. 

BUT there is SO MUCH THAT CAN BE SAID!

wink

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
7/29/20 1:59 p.m.
Paul_VR6 (Forum Supporter) said:

There is an almost infinite amount of nuance that can be applied and in the end you still need to choose and live with it.

i have seen a 12:1 496 with iron heads live just fine on Sunoco 94, because it was in a '56 Chevy with 4.11 gears.  The engine never got loaded down enough to hurt itself.

 

The same engine would probably tear itself apart at 10:1 if it was in a heavy truck.

GIRTHQUAKE
GIRTHQUAKE Dork
7/29/20 2:31 p.m.

 Would 11:1 be the max for 91 octane? That's my region's max and I'm having some difficulty finding some baselines despite the discussion about cam choice.

I love the idea of dressing it up a little bit to make it -NOT-LS, but more because it fits the aesthetic of the 928 more. I think moving the intake slightly would be fine with cable throttle, moreso because I can't see how it would affect the engine much naturally aspirated.

I take it I need to look only at 243/799 heads Patrick?

NOHOME said:

In reply to GIRTHQUAKE :

like a medicated prairie dog in a manure pile.

I have not mentally made it past this phrase so as to address anything else in your post. Do carry on.

I appreciate alliteration to it's aggressive abolishment in any argument laugh

Matt330LS
Matt330LS New Reader
7/29/20 2:39 p.m.

I ended up with a LQ4 block, forged aftermarket crank/rods/pistons, stroked out to 408 cubic inches and topped with 317 heads and an LS6 intake with aftermarket cable throttle body.  Rough estimate of 10.5:1 compression and I'm running 93 Octane (no ethanol) just because it's available locally and I don't want the fuel to be a question mark.  Although I suspect it'd run fine on standard 91 from the pump with a little ethanol content.  Holley HP EFI to run everything. 

That all fits under the hood of a E46 BMW.

I'm a big fan of being able to Frankenstein LS variants, you'll more than likely be happy with whatever you cobble together.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
7/29/20 3:13 p.m.

I mostly went with the low-mileage LQ9 because I didn't want to tear into the shortblock, and the LQ9 has flat tops which (with proper quench) can potentially cut down on octane needs.  Dishes, not so bad.  Domes... yikes.  They kill flame front speeds requiring more ignition lead which often equals higher octane requirements.

 

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) Dork
7/29/20 3:27 p.m.
GIRTHQUAKE said:

 Would 11:1 be the max for 91 octane? That's my region's max and I'm having some difficulty finding some baselines despite the discussion about cam choice.

Sorry, another "it depends," are you at altitude? If so, it will behave like 93 does at sea level. Don't ask me why, it just does.

GIRTHQUAKE
GIRTHQUAKE Dork
7/29/20 3:35 p.m.
Paul_VR6 (Forum Supporter) said:
GIRTHQUAKE said:

 Would 11:1 be the max for 91 octane? That's my region's max and I'm having some difficulty finding some baselines despite the discussion about cam choice.

Sorry, another "it depends," are you at altitude? If so, it will behave like 93 does at sea level. Don't ask me why, it just does.

~1,000Ft. above.

GIRTHQUAKE
GIRTHQUAKE Dork
7/29/20 3:36 p.m.
Curtis73 (Forum Supporter) said:

I mostly went with the low-mileage LQ9 because I didn't want to tear into the shortblock, and the LQ9 has flat tops which (with proper quench) can potentially cut down on octane needs.  Dishes, not so bad.  Domes... yikes.  They kill flame front speeds requiring more ignition lead which often equals higher octane requirements.

 

Flat tops for quench before dishes, then domes. Good to know, thanks!

yupididit
yupididit UberDork
7/29/20 4:07 p.m.
Curtis73 (Forum Supporter) said:

I mostly went with the low-mileage LQ9 because I didn't want to tear into the shortblock, and the LQ9 has flat tops which (with proper quench) can potentially cut down on octane needs.  Dishes, not so bad.  Domes... yikes.  They kill flame front speeds requiring more ignition lead which often equals higher octane requirements.

 

Lq9 would be ideal for what I'd want. Naturally aspirated with 400-450hp with an auto to move a 4000lb coupe. 

759NRNG (Forum Partidario)
759NRNG (Forum Partidario) UltraDork
7/29/20 5:17 p.m.

What is nekcar running manifold wise?

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
7/29/20 5:41 p.m.
GIRTHQUAKE said:
Paul_VR6 (Forum Supporter) said:
GIRTHQUAKE said:

 Would 11:1 be the max for 91 octane? That's my region's max and I'm having some difficulty finding some baselines despite the discussion about cam choice.

Sorry, another "it depends," are you at altitude? If so, it will behave like 93 does at sea level. Don't ask me why, it just does.

~1,000Ft. above.

Yeah... midwest, right?  Not sure why some states only do 91.  I understand why Colorado only does 91, but not down where you are.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
7/29/20 5:42 p.m.
yupididit said:
Curtis73 (Forum Supporter) said:

I mostly went with the low-mileage LQ9 because I didn't want to tear into the shortblock, and the LQ9 has flat tops which (with proper quench) can potentially cut down on octane needs.  Dishes, not so bad.  Domes... yikes.  They kill flame front speeds requiring more ignition lead which often equals higher octane requirements.

 

Lq9 would be ideal for what I'd want. Naturally aspirated with 400-450hp with an auto to move a 4000lb coupe. 

They start out from the factory at 345hp and around 10:1.  You can probably easily get to 400 with just a cam swap.

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