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Someone explain to me the theory behind Reverse Split cams?

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Old 03-12-2003, 06:28 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by mike#9:
<strong>

What is ASA? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">A S hitty Ass cam for drag racing <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Old 03-13-2003, 12:30 AM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

I understand the reason for reverse split cams in the sense that they are supposed to make up for the poor flow of our intake manifold. What I don't understand is how this would benefit a stock headed car. The ls6 intake flows in the neighborhood of 280 CFM and the stock ls1 heads seem to flow in the neighborhood of 240-250CFM. Where is the restriction by the intake manifold in a stock headed car then? Seems to me that stock headed cars would benefit more then from a reverse split cam to equal out the difference in the better flowing intake side of just about any head. Maybe somebody could chime in and show me the error of my ways.
Old 03-13-2003, 07:37 AM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

ASA is the racing series that uses sealed LS1 crate motors. They uses the ASA cam in those cars....

As for the record. That record is in stock eliminator. Which has restrictions such as stock lift, but unlimited duration, etc...

I would say the fastest cars all out LS1s out there are the SAM car and a few others. Last quoteed SAM specs are

Camshaft duration @0.050: 260/264

Lift: Intake .670 w/ 1.70 rocker

Exhaust .640 w/ 1.70 rocker

Lobe separation: 113 installed @ 111 ICL


Also, I think a revised manifold would benefit the cars, but you would also need a cam to take advantage of it. A bigger box with bigger, but shorter runners would probably do the trick, but the cam, etc... would need to match., Right now everyone is tuned for the stock manifold. I think the Hogn manifold would be a nice piece with the right cam....

<small>[ March 13, 2003, 07:39 AM: Message edited by: J-Rod ]</small>
Old 03-13-2003, 10:25 AM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by verbs:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by mike#9:
<strong>

What is ASA? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">A S hitty Ass cam for drag racing <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">LOL! I agree. I'm still trying to figure out why GM cams were ever brought into this discussion. GM has yet to design a street/strip LS1 cam for stage II ported heads, 1 3/4" headers, and open exhaust. They do not make an LS1 cam that I would even begin to consider regardless of their R&D budget.
Old 03-13-2003, 07:45 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

Most of the GM cams are purpose built for specific applications. ASA & Grand Am. In both classes there were restirction on vavle springs and heads. Working within those guidlines Gm designed two cams that make good power FOR WHAT THEY WERE INTENDED TO. No, they probably aren't the best drag car cams. But, if you were extremely price concious about you upgrades I would think that a set of CNC ported LS6 heads and a Grand Am cam with a set of headers would put you right up there with the Cartek and LGM packages, and ahead of most other shops. Keep that in mind.

The ASA cam is a circle track cam. Circle track cams aren't for drag cars. Go look in any cam catalog, they get a differnet section. My point on those cams is that GM built the LSx series motor. They have more R&D and dyno time in the thing than every ls1 tuner combined and probably multiplied by a factor of 100.

The ASA and the Grand Am both use conventional splits nad they are on open header cars. That was what I was trying to point out...

If a reverse split would make more power in a racing series don't you think GM would be doing that... Especially in the Grand Am Series.
Old 03-13-2003, 08:55 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

"The ASA and the Grand Am both use conventional splits nad they are on open header cars. That was what I was trying to point out...

If a reverse split would make more power in a racing series don't you think GM would be doing that... Especially in the Grand Am Series."


Right. And my point was that just because those engines run a conventional split doesn't mean that reverse split cams are necessarily inferior for a street/strip engine given that your typical street/strip LS1 engine is alot different than those engines. It's apples and oranges, IMO.

Do those engines run stock LS6 intake manifolds? Do they shift at ~6400-6700? Are they nice and streetable? Pump gas friendly?

If the answer to any of these questions is no, then I don't see what they have to do with this discussion since the answer to these questions for the reverse split cams I see for sale is yes.
Old 03-13-2003, 09:00 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

"If a reverse split would make more power in a racing series don't you think GM would be doing that... Especially in the Grand Am Series."

Aww heck, J-rod. Totally disregard my last post. I thought we were talking about LS1 street/strip engines. I didn't know we were talking about circle track or road course racing. I'm sure GM did a perfectly good job designing the cams for that type of racing. Now if they'd just design one for our needs we might see them turning out reverse splits! <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Old 03-13-2003, 09:48 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

The Grand Am car run an Ls6 intake, wheel to wheel headers (just like LGMs), a lightweight clutch and flywheel, etc... But they are very close to regular street cars. They run on pump gas or unleaded race gas.

GM's goal with that cam was the maximum power an torque it could develop within the confines of a cnc ls6 head and stock springs.

I think you have to admire a cam that makes the power and torque it does. My thought aare that this would be a good candidate for a drag car.

But the ASA I don't feel would be. A road course perhaps, but I think the 'gib' cam would still always be ahead.

I'd say with over 30 cams tested to get the Gran dAm cam that if a reverse split would have gotten the job done they'd probably have done it...
Old 03-13-2003, 11:26 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

J-rod, I don't think anyone is saying that the reverse split cam is the end all be all design for the ultimate race only camshaft. I think, as pointed out earlier in this thread, the idea with the reverse split is to make great power while retaining a nice, usable power band and good streetability. Basically, it's about taking a given amount of streetable total duration and making the most of it taking into consideration a free flowing exhaust system and a somewhat restrictive intake.

The Grand-Am cam has a total duration of 490 and an LSA of 106...talk about a rough idle and peaky power if we're talking 346 CI. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> Also, we're not limited to CNC heads and stock springs (how do they make stock spring work with that thing anyway?)
Old 03-14-2003, 01:41 AM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Colonel:
<strong>Also, we're not limited to CNC heads and stock springs (how do they make stock spring work with that thing anyway?) </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">They are using '02 LS6 springs and '02 lightweight LS6 valves. The lightweight valves allows them to get by with less spring pressure, which is a good idea if you are trying to turn any kind of rpm with the stock hydraulic lifters.

Jason
Old 03-14-2003, 08:56 AM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

Colonel you are 100% right on the money. J-Rod you keep bringing these GM circle track "race only" cams. Why are we even comparing the two? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> The two cam are not even in the same city much less in the same ballpark. One cam is made to make power in a very narrow power band. Ours, and many others, are street cams that we race at the drag strip. Please don't take this as a flame because that's not what I'm trying to do but are you so narrow minded that you can't see the difference.
You build a motor with a "cup" cam and I'll build one with our TR230/227 cam and lets do a real world comparision. You may win on the dyno and on a circle track but when we compare idle, drivabilty, emissions, low and midrange power, drag racing and more importantly the fun factor, who's going to when? Sorry buddy but you'll lose. Also what cam would most people rather drive.
I've said this before and I'll say it again. We didn't design these cams for circle track or to make the "most" power out there. We designed them to make as good of power as larger cams but with better idle and dribabilty. Mission acomplished. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />


Paul
Old 03-14-2003, 09:12 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

I am using the 'gib' cam as an example. Simply because that is what GM went with. With all the dyno time at their disposal, all the R&D time they had, all the dyno time they had. And they choose a standard split. Keep in mind the Ls1 was in R&D for more than 5 yrs (I saw one of the early LS motors in a Camaro on loan to Johnny Klevenhagen here in Houston in the early to mid 90's and he in fact made a pass at a National event in the car (but they shut the clocks down so no one would know what the car was doing).

I am not knocking TR for using a reverse split, on the contrary I congratulate you for thinking out of the box and trying new things.

But, I kept seeing the point y'all have made jump back and forth. Oh, GM used a stadard split on the stock cam in all the LS series because of the factory intake and using exhaust manifolds. But, that is not what you would use in a race motor. So, I point out that is exactly what they are using in their "race" cams. Oh, but that isn't good enough now either.

I have posted number for a cup cam in a Street car.
RWHP Dyno Numbers - w 3.73 gears, and 91-octane pump gas.
45xrwhp @ 6500rpm (over 450 from 5900 to 6800)
41xft/lbs @ 5000rpm (over 400 from 4400 to 5700)
and it makes power to 7000 and it uses stock z06 spings, and small valves...

Anyhow, I agree folks have been making good numbers with reverse splits, and the small exhaust does help with lope which may in turn help with customer satisfaction. (I.E.) some folks don't like lumpy cams. But, I think we all know that emission and drivability has alot to do with overlap and LSA. Hence the Z06 with a 116.5 LSA

Again my thread isn't to knock TR for making reverse splits. I just think if power is what you are after, there is more power in either a symetrical cam (Cartek) or a standard spilt (GM, Comp, and LGM).

I would also say that the I/E flow percentages would have alot to do with my selection of exhaust profiles. At 65-70% I would look at standard splits. In the 80's I would start looking at symetrical cams.

For me, I don't think I would ever use a reverse split. But, I know alot of other folks will, and they will be quite satisfied with them.

I will also reverse the right to change my mind if TR can dyno a bunch of grinds and come up with some magical reverse split that kicks the snot out of some of the current x2 packages. If they can provide a H/C (hyd., not a roller) 346 with a reverse split in the 460's I think everyone will be interested.

I will say that I am interested in their upcoming dyno program they have been discussing, and am interested in hearing what they find on the dyno.

I would like to thank everyone who has taken the time to read this thread, and to those who have contributed (even if I disagree with you). I think discussion like this are good. It gets folks to thinking, and more importantly it may make a fe of us try new things (which isn't always a bad thing).

Again, feel free to disagree with me on any of this and run whatever you want in your own ride. All I care about is what works, and what makes the most power, I don't care who makes it...

<small>[ March 14, 2003, 09:15 PM: Message edited by: J-Rod ]</small>
Old 03-14-2003, 10:45 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

For us people in CA (and anyone else who has to pass stringent smog laws), i honestly think the reverse splits would work best. This is because they have lower emissions due to less valve overlap because the exhaust valve staying closed longer and less raw gas exiting out the exhaust valve etc etc blah blah blah.

Another group of people that i think would benefit from the reverse splits are people with daily drivers that will log a lot of miles in traffic and varying conditions. A reverse split would be much friendlier. it would have a much better idle, and have more low end and midrange torque. this is not only good for regular driving but more fun around town. besides if you ask me the losses at the top end are marginal compared to the benefits of more torque.

the people who would benefit from a standard split are those who dont have to pass emissions testing (lucky bastards) and dont care about how rough and tempermental their car is. this also applies to cars that will see much more track use and are going for low times and high dyno #s.

So in all, my take on this is if you fit into the reverse split category then id go with it. besides i think low end and midrange torque would be better for stoplight to stoplight races anyways.

If you fit in the other category go with it...youll be damn fast and proly showin us who have to go with reverse splits (emissions is my reason) yer taillights.
Old 03-15-2003, 09:59 AM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

I live in Harrid County which has emissions testing rules just as stringent as anywhere including Cali. We have had the sniffer test, and now we have moved to a dyno test. One of my friends has a Hammer cam/MTI stage II's in his A4. On the sniffer it passed much better than stock. It had no Recordable emissions in one of the categories. The folks were shocked. That is one of the benefits of good tuning, and its a symetric profile.

Now one of the things I can do now is since Harris County has all the hardcore testing all sites are required to have OBDII testing equipment. That means you can come in with open exhaust and a 106LSA, and as long as it passes on the OBD then you get a sticker.

In Cali are you required to have both an OBD scan and a dyno test?

<small>[ March 15, 2003, 10:00 AM: Message edited by: J-Rod ]</small>
Old 03-15-2003, 02:19 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

J-Rod,
As far as i know, in CA, not only are they switching to dyno testing, but they ALSO will plug into our computers to see if it is modified. <img border="0" alt="[cry]" title="" src="graemlins/gr_cry.gif" /> This will make passing VERY hard. damn,I hate CA <img border="0" title="" alt="[Mad]" src="gr_images/icons/mad.gif" /> , i wish i could go live back east again. but anyways...J-rod, you said that there were smog benefits to using a symmtetrical cam, wouldnt there be even more of a benefit then to use a reverse split, or am i wrong?
and yes, i too have heard these stories of guys waltzing into smog testing with these super tight LSAs and huge cam profiles, along with headwork and LTs, and still passing. and most of them will say "with the right tuning any LS1 can pass smog." is this true? I mean, hell if it is, i will be one happy Californian, because with these new laws it seems as though i will never be able to make my car as fast as i want it. i dont even know how im gonna pass inspection when i get my long tubes, much the less cam and headwork.... <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />
so if yas got any ideas or tricks either post it or PM me, thanks
Old 03-15-2003, 02:24 PM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

Upon reading my own post i have realized that it really doesnt have that much to do with the rest of the thread. so i would like to emphasize my question that i did ask...

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Siggy33:
<strong> J-rod, you said that there were smog benefits to using a symmtetrical cam, wouldnt there be even more of a benefit then to use a reverse split, or am i wrong? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">what do you think...are there any benefits? i always thought that reverse splits were the best compromise for emissions and power.
Old 03-17-2003, 07:20 AM
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Default Re: Someone explain to me the theory behind Reverse Split cams?

No, in a situation where emissions are a big concern then a reverse split will help you out. One of the big issues with emission is overlap. Lumpy cams with a lot of "chop" (overlap) will pretty much fail you. Also the LSA has a big effect. I.E. a 112 will have a tougher time than a 114. A 114 stands a pretty good chance of passing (provided that the tune is right), my z06 has a 116.5 and will pass with ease. Cartek has their X2 pkg which is symetrical and has passed all the NJ emissions with no issues.

<small>[ March 17, 2003, 07:21 AM: Message edited by: J-Rod ]</small>



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