Sorry if it's a repost,but some good info here. Looks like the LS6 intake is the bang for the buck and good streetability.

http://www.gearchatter.com/viewtopic10974.php



Intake Test: LS2 vs LS6 vs FAST

We here at GearChatter are committed to providing real answers to the questions everyone is asking when it comes to engine components and the ability to make horsepower. Intake manifolds have been a hot topic, so we had some independent testing done by a professional engine/dyno facility to find some answers! Read’em and discuss --- there is more to come!

Engine Description: GM Performance 5.7L LS1 crate engine tested with Kooks F-body 1-3/4” long tube headers with 2-1/2” lead pipes into Flowmaster mufflers. Factory front drive accessory was used with the water pump, power steering, and alternator. Stock LS1 heads and short block, GM Performance “Hot Cam” with LS6 valve springs are the only engine upgrades.

Engine was tested using the factory PCM. The intent was to test the intakes just as the average user would install them --- no custom programming. Granted, custom programming would increase the power of each combination somewhat, as the detailed info from the tests indicates that each intake had some “holes” in specific RPM ranges that could be corrected to improve the HP of each intake. But in the end, the general tendencies would remain as they are. We have over 30-pages of test info for those who want to dig-in to the detailed data and we would be more than happy to mail this info to anyone who wants to see it for the price of the copies plus postage.
We have summarized the test for your viewing pleasure.
Some points to keep in mind; we have included averages for specific RPM ranges – Low, Mid, and High. The engine does not stay at a constant RPM, so we feel it is important to see these numbers. Hey, if you leave the starting line at 4500 and shift at 6300, then it might be nice to see the average for that range!
Do not forget, this is a 5.7L with a rather mild cam upgrade! Engines with different RPM ranges and more cubic inches may have totally different results. We are just reporting what we tested. And BTW, we will have some intake results for a 6.0L LS2 very soon!

Test 1 – LS6 Intake with Stock 78mm TB.
The best low and mid range numbers of all the combinations. The LS6 would seem to be the best bet for all-around street driving/racing on this combination. As the engine moves past the 6000 rpm range, the LS6 plenum volume may not be large enough to keep up with the demand for more air. The LS6 made the highest peak torque number.

Test 2 – LS2 Intake with Stock 78mm TB.
We made a thin adapter to bolt the 78mm TB onto the LS2 intake to see the real comparison from LS6 to LS2.
Want to kill 10hp and 10ft-lbs of torque? That is what happened! Obviously the 5.7L does not like this big intake. We thought the 78mm TB might help by keeping the air velocity up on this big plenum intake. Did not work!

Test 3 – LS2 Intake with FAST 90mm TB.
As long as we were here, let’s try it!
Our intuition told us that this probably would not work and it didn’t! But it is interesting to note that the power was not significantly hurt from the addition of a bigger TB either. In fact the two curves are almost identical.

Test 4 –FAST with the FAST 90mm TB.
Now it is obvious that the FAST wants to make more power up high --- above 6000rpm. But when you look at the low and mid range the LS6 is definitely better, but when you hit 4000rpm the FAST wants to carry the torque curve further than the LS6. The FAST made the highest peak HP number, 432hp @ 6000rpm.

Lots to discuss here; plenum volumes, runner lengths, TB sizes, what would ported heads do, etc. We have heard of people bolting on the LS2 intake to a 5.7L and the car felt lazy, it is easy to see why! The engine lost torque everywhere!

 

Good info

 

Interesting yes but definitive, I wonder?
If you do not tune for an intake or TB combo how can it perform to potential?
They bring in lots more air and have the same fuel curves so get disappointing power due to really bad a/f ratios.

 

Very cool

 

Great post & info!

- Matt

 

Well people that will be putting in either the LS2 or the FAST arent going to be running such a lame combo as the one in the test!!! Unported heads, hotcam (who uses the hotcam anyways?) 2.5 mid pipes, etc.
These intakes shine on H/C and big cube setups, not stockers! What a waste of time.

 

I changed from the LS2 to FAST on my C6. 22 HP difference with no tuning. That's good enough for me.

 

intakes dont need to be tuned, you might get 1-2 more horsepower but thats not worth the price of tuning.

 

 

lol i agree

if u running even a somewhat aggressive setup, the fast 90 is almost a must

 

Some guys simply won't believe the value in tuning the PCM to work better with the sum of all parts. Then codes get thrown because Xpart has now effected the A/F ratio and we see posts of "Help!!! Got XYZ Code" 3 months down the road...

I bolted on LGM headers, SLP 3inch Cats, 3 inch Xpipe, and borla singers, along with an LS6 intake and Shaner Ported Tbody... We hit the rollers and the car was running PIG RICH... It also made some good numbers, which might be "Good enough" for some... I'd like my car to make:

Healthy peak HP
Healthy Peak Torque
Be tuned to my specific Application

Bolting on a bunch of parts will net you some HP, but if it isn't tuned properly, you won't get an optimal state for the PCM and the powertrain to work in harmony with. Fouled plugs and thrown codes are a tank of gas away (Or maybe 10 tanks, but you get the drift!).

In my Ls1-Edit session on Friday, I lost peak torque (6Ft.# down from 359 to 353) but gained HP (Up 4.5 from 330 to 334.5) and more importantly, We balanced the air and fuel ratio for an optimal safe tune across the rev range. I now have 300Ft.# of torque or MORE from off idle all the way to redline. I make over 350#ft. torque from 2000-4400RPMs... That is REALWORLD usable power. More importantly, I can take that combo to the track and beat on it all day on a road course, and drive it to work on Monday.

Bolting these parts on without retuning the PCM is worthless data in my opinion! Again, it's just MY opinion, which is all that matters to me!

Cheers!
Mike

 

Great post! Thanks for the information.

 

if you want to spend all that money to get it dyno tuned for that little power then do it, its your car. i was just saying that it is not necessary to tune after these boltons, I had all boltons on my car for 7 months and never had a problem and no codes and car ran good. Now i have a big cam along with boltons so a tune was very necessary. You can tune a bone stock car and make it run better if you know how to use the hp tuner. If you can tune your car yourself than i would do it, i tune my own car with hp tuner, but if your going to pay some shop 500 bucks then thats not worth the money.

 

Thanks for the Post!!

Tuning is a BIG help with Part Throttle drivability and idle quality. Once your Wide Open Throttle, through the MAF, it's just Air/Fuel.

From the report it looks like the LS2 Intake provides too much volume, at low flow, for a 346 with a low lift cam.

 

Yeah with a big cam or FI, not with just an intake and headers. so your telling me that when you put an ls6 and long tube headers on your car doesnt run good on stock tune. you wont have a problem with part throtle or idle until you get a cam.

 

Spend all that money on a tune? Uh, you spend all that money on all those parts and then not spend the extra $300 to get it all dialed in, and then foul plugs because your AFratios aren't right??? Header kits alone are running $1500-1800, plus any $600 catback, plus the $350-700 for any one of these intakes... At that point $300 is a drop in the bucket and the best money spent to ensure SAFE power for the long haul.

Not going the extra step makes absolutely NO sense to me, but hey it's your car, Have fun.

Mike

 

I paid $300 for my LS1 Edit tune... And that little power was as I stated before, for MY specific purpose for the car. They could have gotten me more power on a different tune, but not for long periods of wide open throttle situations, such as track days.

Look, my point is that guys are spending a LOT of money to mod their cars. So why not take the next step to optimise their combo? Spend what, $3000 for boltons not including the install that some guys pay because they don't turn wrenches? At that point $300 or even $500 for the right safe tune seems like money well spent and the next logical step... And your car may not have thrown any codes. Good for you... As soon as I bolted on my headers and exhaust, mine threw codes within 70 miles of driving. Every experience is different.

Mike

 

Thanks for the post - nice reference point.

 

People think because they pay a vendor $500 for tuning it is going to unlock some magical HP. This was the test I was waiting for. I almost ordered a FA$T intake too.

 

What i am saying is that a tune for 500 bucks for maybe 5 horses if your lucky isnt a good bang for the buck thing to do. There are a lot more people running boltons without a tune than there are with a tune. im just saying a lot of people that do headers usually do a cam or FI down the road. If you do that and tune after headers, then youll have to tune after cam or FI and that will be another 500 bucks.