In looking over the flow data on ported heads, a couple of thoughts come to mind. In the flow data that I have seen posted, people are getting some really promising numbers out of the LS1 and LS6 heads. These flow numbers in a conventional 23^ SBC would be good for 700HP.

The one thing I do see is that as soon as you throw the LS1 or even the LS6 intake into the equation then you immediately take what I would consider a fairly big step backwards.

In looking at the article on the SAM Camaro, they "obtained" a GM prototype manifold which had shorter runners and a bigger plenum "similar to the LS6" which flowed 20 CFM better than the LS1 and after porting picked up 10 more CFM.

So, I think we all agree that even the LS6 manifold, even as good as it is has its limitations. And, the new Holley intake may provide some benefits also. But here is where my question splits off a bit, so please bear with me.

In the days of the L98 SBC. It, like the current LS motor used long runners to assist in the production of torque. Once you began to upgrade the motor, you began to run into the limits of that manifold.

Several options were avaliable including big, or siamesed runners among others. Lingenfelter came out with his "box ram" which seemed to work well, and finally you had Myron Cotrell over at TPIS who came out with the mini-ram.

Over time it has been shown that on bigger inch motors the mini-ram seems to be the best choice. Shorter runners and a good sized plenum seems to be the hot ticket over small plenums and long runners.

So, here is my question/observation. Has anyone ever tested any of the manifolds out there to see if there are any gains? A couple that come to mind are the Hogan, and the nitrouswarehouse.com "Spider" and "Super Spider" plus several others. All of them have the characterics as I described above shorter runners, and bigger plenums. The Holley looks to be a copy of the LS manifold with bigger runners, but with benefits such as the ability to get in and port it.

To me it just seems like some of the money is wasted on port work since all you have done is move the restriction around a bit. To me it is like restrictor plate racing, or running in a 2bbl class.

Just from the numbers I have seen, and looking at the loss figures, if a better manifold was avaliable it appears on paper (for all the good that is) that for instance a stock LS1 with no intake flows as well as an LS6 with an intake.

In effect you see about ~15-20Cfm of loss on a stock bore motor with an intake vs without. I am sure that as airflow requirements go up (ala big inch motors) this become an even bigger hindrance.

Now obviously we need an intake. Think about it this way. An intake would be the equivilant of 1 "stage" of port work at least. For instance as a total package a set of stage II heads with an intake would outflow a set of stage III heads without. And as we all know airflow in/out = HP.

Anyay, maybe this has been beat to death already. But I am simply wondering if anyone has any real data regarding a manifold swap. It just looks to me like there are some major power gains there just waiting to be unlocked.

<small>[ May 06, 2002, 08:45 AM: Message edited by: J-Rod ]</small>

 

You are certainly on the right track here. I have talked to some very good head porters who agree that intakes are certaily the limitation in making really good power with these motors partiularly in the larger sizes. Heck, the major compnents to build 440+ ci motors are readily available, but few want to try due to feeling that that is beyond the point of reasonable returns. There has not been much data on 'specialty' manifolds you mention due mainly to cost. The spiders are more than $3K as are the other fabircated offerings and most of us certainly don't wnat to fork over that much cash just to be a the test dummy.

 

Nice name. This is gonna be confusing.

 

Don't forget the FI folks <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

I was hitting the limits of the LS6 manifold before i tore into the motor.

I have a Holley to go on the new setup, and still have the LS6 to compare with

While a clean up and port match for the Holley is in store, the biggest mod will be serious shortening of the runner length.

I can make up for the lost torque from changing the manifold tuning with the turbos, and the upper RPM gains should more than make up for the extra throttle i'll need down low.

I personally wouldn't spend $3k on a sheetmetal intake. The stock manifold design is good, so why not just "tweak" it to open up the flow.

 

www.ls1speed.com has a few sheetmetal intakes around. One has been dyno tested on a stock cube 346 H/C A4 and it made more power and torque.

I am supposed to be trying out a different one that will use the factory fuel rails. I hope to have it in two weeks. Since my car has like 10+ dyno pulls on it this year, we have an excellent baseline.

John
450rwhp unlocked
502rwtq

ARE 422ci

 

Thanks for the responses guys. PJ - I am interested in what you find. Especially on bigger inch motors.

J Rod - Sorry dude I have been using this name on BBS/forums/you name it since the early 1980s. Actually this is the first time I have ever seen anyone else use it.

-Jarrod

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by J-Rod:
<strong>J Rod - Sorry dude I have been using this name on BBS/forums/you name it since the early 1980s. Actually this is the first time I have ever seen anyone else use it.

-Jarrod</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Maybe you mean late 90s? I don't think there were too many boards around before 1995 or so <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Which one of you two was on another board trying to find reverse in your M6? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

PSJ... looking foward to seeing that intake <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

Jrod, i can tell you flow loss even with excellent carb. style intakes falls in the 10-20 cfm on generation 1 and 2 small blocks. I am not fighting the idea about bigger intake with shorter runners making more power, but street strip LS1's with under 7000 rpm shift points would give up a decent amount of usable power by stepping up in this direction. Race sized ports shouldnt have less than 230* duration cams, this means compromising low speed driveability and torque in a heavy vehicle. Strokers and bigger cubed Ls1 will soften the hit some, but you have to plan for the big picture, IMO.

 

Um... sorry guys, the World Wide Web (born Circa 1994) != the Internet, and certainly Buliten boards were around in the 80s. A bulliten board was basically a guy in his mom's basement with a couple modems and you would dial up and talk to his computer. not very high tech, but it was the **** in it's day. The "Internet" as a whole has been around since the '60s.

Some fun "internet" facts:
1) The "Web" is not the "Internet"
2) The first message posting community like this one arived in 1979
3) Quake was not the first online game
4) "Napster" was not the first file sharing program
5) Microsoft did not invent windows
6) or office software
7) or the web browser
8) or anything, for that matter, except
for maybe macro viruses and the sucky programs
that run them.
9) email has been around longer than most of you
10) Heck, it's been around almost as long as the "F-Body" (1972)

 

LS1derful - good points. As I said, I was just curious.

J Rod and Biochem - That shows your age (and I don't mean that as a flame). BBS were around alot longer than that. I started logging into BBSes in around 1981-1982. I used to log into BBS around the U.S. that was in the days of fone phreaks, k-kewl warez, AE Catfur boards, and things like TI64s, Apple IIs,and Color Computers.

No, I did not invent the internet. But
I am willing to bet I was on it long before you had ever heard of it...

I used to be grateful for a 300 baud modem. So, don't give us old codgers too hard a time.

But, thanks for the heads up on the names...

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by J-Rod:
<strong>Thanks for the responses guys. PJ - I am interested in what you find. Especially on bigger inch motors.

J Rod - Sorry dude I have been using this name on BBS/forums/you name it since the early 1980s. Actually this is the first time I have ever seen anyone else use it.

-Jarrod</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Early 80's huh? I guess that means you invented the internet then, not Al Gore right? lol Well I registered here first so that's all that matters. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" /> Seriously though it doesn't really bother me, I just wanted to let you know that I existed just in case someone gets you confused with me.

Jarod

 

I think the biggest factor in designing intakes is whether or not it is going to fit under the hood of a F-body. Well, hood and cowl. Otherwise, it is not goign to be too marketable, meaning HIGH PRICED. Look at the price of the Hogan intake. Nuff said.

Now if the LS1 was installed in a GM A-body or something with some hood clearance, there could be some major intakes showing up and making huge power.