Runner length determines about 99% of your peak. TPI cars have about whopping 17" runner and thats why they peak about 4500-4700. As you increase displacement you will also lower your peak as the manifold will have an even harder time keeping up. Do not be afraid of the carb intake it is extremely nice and 100% better than the ls1 carb intake.

 

What's your opinion on the ported L76 intake offered by:



It still doesn't change the runner length. Do you think porting will be effective?

 

That is not correct. Go the the Chevrolet web site. GM sets the LS3 redline at 6500 rpm's.

 

Yeah but the redline and where the motor peaks are two completely different things. The LS3 does not peak at 6500, more like 6000

 

Stock LS3 isn't 400 some cubes, either.

I don't think the RPM the L76/LS3 is designed to peak at is as relevant here as the fact that they're simply not able to flow enough air to support 400 some cubes. I haven't seen this problem yet on stock-displacement 6.0s or 6.2s, but it's been seen on more than a few 400+ cube motors.

 

Did you even click on the link? They dyno'd a stock 2008 Corvette. Not only did they post the dyno chart, but they posted a video of the whole dyno session. How could you believe manufacturer hype over actual proof on the dyno? By the way it pulled 392 RWHP @ 6000 RPM and 378 RWTQ @ 4700 RPM.

At 416 cubes, my engine peaks around 6000 RPM, just like the LS-3 did. I really do think that our intake is the bottleneck.

So back to my question concerning the L76 intake:

Do you think that porting the L76 intake will be effective? It still doesn't change the runner length.

 

What are the disadvantages of this kind of setup? Just wondering if it has that much better flow, why don't we see more of them?

 

Mainly, its cosmetic. The combo of a front fed plastic intake and FRC's looks cleaner. The other one is hood clearance, mostly for you F and Y body folks. The carb flange on the GM manifold is 5 inches above the valley cover, and the Edelbrock part is ~5.4" IIRC. So you dont have a lot of room to turn the air 90 degrees from front feed to top feed, and not have a restriction there. Which is why you see most f bods notching the area where the wipers are for clearance. The other thing is the Al intake is more prone to heat soak than the plastic.

And its cheaper than a FAST, even with all the other BS.

Ive got one of the new edelbrock cast Al elbows on order, if/when jegs gets it to me, ill post dimensions and flow. Im thinking thats the best bet.

The reason you dont see more of them is stupidity, and availability. These are relatively new parts, compared to the LS family's 10 year age. GMPP makes three, LS1/2/6, LS7, L92/L76/LS3. Im pretty sure edelbrock only has a LS1/2/6 version at this time, but i think they have both single and dual plane versions (GMPP are all single plane). They pop up mainly on FI cars, those guys understand airflow. Most NA guys seem to ignore the air flow, and focus on their cam lobes and head flow. According to Comp's Camquest soft ware, a max flow single plane is worth ~100 hp over their own FAST90, everything else being equal. Heres a post i made o that effect on another forum:

 

You are basing this **** off of computer software? Kidding, right?

 

No, I came to this conclusion other ways (math, observation, etc), but Im backing it up with data from a program as well.

Nobody in their right mind thinks that our long runner plastic intakes can properly feed a high RPM, moderate cube motor as well as a short runner carb style intake can.

And while I dont trust the 100 HP figure that the software spit out, I do feel it is a significant gain (30-40 HP) over the FAST.

The pulsing effect of a short runner is much better for a high RPM engine (over 6k), plain and simple.

 

BEEN THERE... DONE THAT. YA GOTTA CUT THE HOOD UP ON AN F-BODY!

 

Combo, combo, combo. Its all about the way the intake/heads/cam/engine work together. These rec-port heads might have AWESOME flow numbers, but some of these guys have no business running them. Not to mention, the guys that DO have the engines to take advantage of them are kind of the pioneers at this moment, there isnt much real world information on them compared to the cathedral port heads.

I say good luck and make sure to post the results so I can copy the setup on my 454 build.

 

Good point. The main reason they turn up on less than ideal motors is cost. And a 364 does not need this kind of air flow unless you run high RPMs. But then it gets saddled with a crippling L76 intake. I find it funny, but hey, not my car.

It is new territory. Ive done all my own R&D on these heads, and cut a perfectly good one to bits. And when I get my 427 done, you'll have all sorts of data to use on your 454 build.

 

you better have one rank *** 6.0 if you put these kind of heads on it. lol.

what about throttle bodys? isnt a 90mm only something like 1000-1200cfm?

 

I was thinking the same thing.

Maybe 235/245 range

 

Wrong, Didnt have to. Try a direct port & tb plate! If you need help, Email Aaron @ intakeelbows.com.

 

Will LS7 intake accept TB, injectors, etc....If so I'd rather go LS7 intake & have it ported if you need more, you know they are good for 7K on stock LS7 with 427cid...