Very interesting. Some of it, I can grasp, but I think I'm more inclined to do hands on testing until I find the one that works for me.

This summer I plan to test out a few cams to see what the differences are.

 

J-Rod,

With all due respect I wouldn't hold the Hot Cam up as an example of anything great that GM has done. Almost every aftermarket tuner has been able to put out a more powerful cam than that one.

As far as the Grand-Am camshaft is concerned, what can I say? I don't know the particulars of that class but I would guess that there is something going on with the exhaust system that is restrictive because of class rules or the chassis of the car. A normal split is a crutch around this.

Also GMPP per se doesn't do R&D on their race stuff as much as they rely on outside contractors and race teams for feedback to tell them what works. There is no way they are doing the same level of testing as on their everyday bread and butter passenger car stuff.

I also know for a fact that at least one LS1 stock eliminator racer (who owns his class)is using a reverse split cam. These seem to be being used with some regularity in this class of racing.

I'm not saying that a reverse split is always right or not. Ultimately the correct choice of cam depends on a lot of factors such as intake choice, exhaust system, drivability, intended usage, etc. Sometimes it is important to keep an open mind, just because GM is doing things a certain way doesn't mean that is the only right way to do things.

We have tested A LOT of cams in our own cars and the reverse split was our best performer for the exhaust systems we are using and the RPM band we were trying to achieve. We have tried normal split pattern cams as well and they didn't work for us.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">
the HOT cam,
LS1 Hot Cam, 219/228 Duration @ 0.050, Hydraulic Roller Camshaft Kit
Price: $399.50 Part # 12480033
Advertised Duration Int.: 279°
Advertised Duration Exh.: 287°
Duration @ 0.050" (I/E): 219°/228°
Lift (I/E): 0.525"/0.525"
Lobe Separation: 112°
RPM Range: 2200 - 6500
Cam Type: Hydraulic Roller
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yeah, GM did their LS1 research on this one. <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

These are the SAME EXACT SPECS as an LT4 HOT cam - which was released what, a couple years earlier?

So I guess the LT4 and the LS1 have the same characteristics, eh? <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

-Andrew

 

if you had a single/reverse pattern cam(say 224/224 561/561 114 or a 227/224 569/563 114) with a tighter LSA say 106* what would that do for helping the intake side of things.

 

If the LS6 intake is so restrictive (I am not saying it is not), why doesn't someone design a new intake?

 

I agree that GM has more money to spend on R&D, but they also have to make cams that meet emissions standards, don't they?
I'm sure that none of the reverse split cams would pass a sniffer test.
Also, does anyone know if GM designs these cams using the stock manifolds? Or do they design them with headers in mind?
Matt

 

In my "real" life/job, my main function is to solve engineering problems in the real world once the "engineers" have finished their job on paper and theory. One thing I can tell you... Just because something has always been done that way doesn't mean it is the best way. There have been many days I have had to pull out the torch/sawzall/grinder and re-engineer a piece of equipment just so we could run prodution.

Now in the last couple of years I've had the opportunity to work with Geoff, Jason and the rest of the team at Thunder. One thing I can tell you... We are consistantly trying new and different things in the quest for power. I hate to use the cliche of "thinking outside of the box" but I think that definitely applies here.

Sure most dual pattern cams are "conventional splits"-- read that again "conventional". A dual or split pattern cam is by definition one in which different lobes are used for the intake and exhaust on the same cylinder. Just because the majority of the cams most people know about use more duration on the exhaust side doesn't mean "reverse" splits are anything new. These cams work great at giving you more high RPM torque (hence power)without the sacrifice of low RPM torque. This was EXACTLY what Geoff and Thunder set out to do with the 230/224 cam. I was there during the initial discussions and also helped swap a few cams in the "R&D" phase. All I can say is that in this particular application, it works. Its as simple as that. The TR 230/224 is an awesome daily driver cam. There aren't that many cams out there that you can slap in in a few hours and with stock heads make over 400RWHP, with the driveability of this cam. I don't think Geoff or Thunder ever tried to tout this cam as anything other than that.

Most of the racers on this board not only race their cars, the drive them too. That is the market Thunder caters to. That doesn't mean we don't build all out race cars. (some of which still creep around on the street... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> ) Some of those cars have used single pattern cams, some may be using "reverse" splits... The point is, if it works then, WHY NOT???

Maybe there is a fluid dynamics expert on this board. I'm sure GM employs a few. Ask any of them if they have totally and accurately modeled the entire combustion process of any internal combustion engine to the point that they can plug in cam specs and know what will happen... I cam promise you, even with all the Cray computer time you could buy, you will still have to try it on the dyno and the track.

Sorry to ramble, but for someone to out-of-hand say something won't work just because the don't like it or because their theory doesn't agree, just look up the meaning of the word theory...

Thanks,
Shane

<small>[ March 07, 2003, 10:01 AM: Message edited by: XtraCajunSS ]</small>

 

I currently am running a reverse split cam (MTI's X1) and while it has performed well I have been a little dissappointed in some respects with it compared to what others have gotten.

The reverse splits seem to be very dependant on exhaust systems as the best #'s seem to come from cars with duals/LT's.

I'm with J-rod on this one I think, because all the crazy #'s I'm hearing from Cartek & LG are from standard split cams. GM's Grand Am Cup cam is supposed to make around 470RWHP with the CNC LS6 heads. The most output I've heard from a reverse split (on a H/C car) is like around 445RWHP and the most I've heard from a standard split is around 460-470. The standard splits still seem to make more power. JMO.

 

The Grand Am cam is also referred to as the 'Gib' cam since Gib is in charge of the racing program. The SCCA disctated the head design, flow numbers, etc... of the CNC head. Hence the reason for the design of the CNC LS6 head. As for a car equipped with a Grand Am cam. It is equipped with Wheel to Wheel 32" race headers (just like the LGMs, just more expensive). With those heads, stock z06 springs, and the Grand Am cam - 470RWHP... This cam was developed because the other grinds GM had weren't cutting it in Grand Am racing. As I said, GM tried more than 30 grinds and spent hundreds of thousands of dollars on dyno time alone, for one camshaft.

I am not saying because we have always done something we should always do that. I agree that it is helpful to question things. But in the case of the ASA and the Grand Am cam those were specifically designed for the most HP and Torque they could produce. Both are for racing only applications.

Look at the stock LS1 and Ls6 cams... Do you think GM didn't spend a bit of time tweaking those?

I know all the arguments about the HOT cam...

Again, I am not knocking TR for their designs. They make good HP, lots of folks are happy with them. My point is simply this I would be willing to bet that if TR were to grind two cams, a standard split and a reverse split that the standard split would have a lopier idle but would make more power.... Maybe not a ton, but more... It just depends on what you are looking for.

JMHO...

<small>[ March 07, 2003, 11:10 AM: Message edited by: J-Rod ]</small>

 

</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> The Grand Am cam is also referred to as the 'Gib' cam since Gib is in charge of the racing program. The SCCA disctated the head design, flow numbers, etc... of the CNC head. Hence the reason for the design of the CNC LS6 head. As for a car equipped with a Grand Am cam. It is equipped with Wheel to Wheel 32" race headers (just like the LGMs, just more expensive). With those heads, stock z06 springs, and the Grand Am cam - 470RWHP... This cam was developed because the other grinds GM had weren't cutting it in Grand Am racing. As I said, GM tried more than 30 grinds and spent hundreds of thousands of dollars on dyno time alone, for one camshaft.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">J-Rod, yep, that's what I'm talkin' about. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Granted these cars have race headers/exhaust, but they are stock cubes and have limited porting work on the heads, not to mention stock Z06 valve springs. How many head/cam cars are out there making 470RWHP - especially on heads whose peak flow drops off at .500 lift.

I too was/am on the "reverse split" bandwagon, but after seeing some of these other results - I think I'm looking to scrap the reverse split cam. It's been a good cam up to a point, but if you want a max effort HP cam, I don't think a reverse split is going to cut it.

 

another reasoning behind it is that obtained from the overlap, there is a definite difference in vacuum pressure. at it's peak the intake stroke can really only achieve about 14.7 psi versus the exhaust hitting ballpark to 1000 psi. the power after the compression stroke is a more efficient vacuum at pulling in more air and thus with the reverse split keeping longer duration more air is allowed to flow in equating to more power.

yes, thank you <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

<small>[ March 08, 2003, 11:17 AM: Message edited by: X']['C WS6 ]</small>

 

This thread is turning out to be very educational! <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

From what I'm gathering in this thread is that the reverse split cams that Thunder Racing designed are trying to have the best of both worlds when it comes to power and daily drivability.

For those of you where daily drivability isn't as important as all out power, then maybe the reverse splits aren't for you.

But for those of us, that want the best possible numbers while maintaining drivability, it sounds like the reverse splits are the way to go.

Can anyone recommend a cam that would work well in an A4 with LS6 intake, LT headers, tuning, and a pulley that is gonna make more than say the TR227 or TR230 and still be a good daily driver cam?

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">but they are stock cubes and have limited porting work on the heads, not to mention stock Z06 valve springs. How many head/cam cars are out there making 470RWHP - especially on heads whose peak flow drops off at .500 lift.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">ok but what RPM are these cams making power like that? my tr230/224 peaks at just over 400@6400rpm. IHAVE STOCK heads, long tubes( into a HOOKER cb), and tuning.

<small>[ March 07, 2003, 04:03 PM: Message edited by: BYBYC5 ]</small>

 

On the Gran Am cam the specs I have seen was a C5 that was not a full out challenge car. It had full exhaust, etc... the RWHP Dyno Numbers with a 3.73 gears, stock tires and wheels at 30psi, stock exhaust system, and 91-octane pump gas was
over 450HP from 5900 to 6800 and over 400 lb/ft Tq from 4400 to 5700.

In a Grand Am car that is in race form, it would have had open exhaust, and a few other goodies. This was in a street car...

 

</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>
Look at the stock LS1 and Ls6 cams... Do you think GM didn't spend a bit of time tweaking those? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I'm sure they did put a lot of time and money on the stock cams. Did they design those "stock" cams around full length header? No they designed it around a cast manifold. Did they have an off-road y or x-pipe in mind? No they had a y and H-pipe with 2 to 4 catalytic converters on it. Did they have a very free flowing catback, or a cutout, or even no exhaust factored into the equation? No they had a more restrictive exhaust system that had to meet federal emissions and noise requirements. Did they design them around a restrictive intake manifold that we are still useing? Yes they did!!!! Get where I headed with this?

We didn't design these cams, and yes I mean designed them and not picked a lobe out of a book, to make the most horsepower out there. We designed them to make close to the same horsepower as the more larger cams out there but have better drivability and idle. I think that goal as well been accomplished.

BTW: What cam holds the 346 N/A record??? A daily driven reverse split. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />


Paul

 

BYBYC5- not to start another vendor war, but the G5X2 (standard split) on a "cam-only" car with stock LS1 heads also makes a touch over 400 RWHP at 6400 RPM. What do your mid-range torque numbers look like??

I'm not throwing any stones here, I'm honestly curious... I'd like to see a dyno plot if you have one, for comparison to another car (similar to yours) using a standard split cam.

I am NOT trying to hijack this thread or start more LGM/TR problems, but I DO think that what I am asking for here would be pretty informative for all of us.

 

burnout ,- thats cool, ill post an updated grapgh as soon as i get one, i think im gonna make a pull next weekend. id be interested to see an overlay as well. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

Very informative topic here guys. But one question I have is...

Which would be more streetable in a M6:

224/224 .570/.570 112 lsa

or

227/224 .569/.563 114 lsa

??????????????????????????????????????

<small>[ March 07, 2003, 07:17 PM: Message edited by: ChiTownSS ]</small>

 

You are correct that GM designed the two cams around factory exhaust manifolds. I certainly agree on that.

But why on the ASA cam and the Grand Am cam which are race only camshafts, and in fact on all their LSx series cams whether or not it was full exhaust, open header, or whatever did GM use a standard split?

Look, I understand that TR has spent a lot of time developing their reverse split cams. And as I have said they do make decent power. I am sure they were also a lot friendlier to tune in the past when tuning tools were less advanced than they are now with LS1edit. They are probably more emissions friendly than a standard split cam also. There are plenty of benefits if those are things that you are looking for. But, I feel there are also compromises there.

I can agree on that. Can you agree that a standard split in an all out application can make more HP and especially more TORQUE than a reverse split?

<small>[ March 07, 2003, 08:08 PM: Message edited by: J-Rod ]</small>

 

J-Rod,

What I'll agree to is this: In the next month or so we are going to build a dyno mule motor with several things engineered to make cam swaps go very quick and easy. We have an extremely long list of cams that we are looking at (hydraulic only). I am sure at that time we should have a very clear picture of what works and how.

I don't necessarily disagree with what you are saying but I don't agree that just because GM is doing something that we can't draw equally valid but different conclusions. If you had read between the lines on my earlier posts I believe the engine is the sum of it's parts, especially it's induction and exhaust systems. What GM factory race cars and street F-Bodies use for exhaust systems may be totally different. All we are trying to say on our end is that we have had great results using the reverse splits with our heads and exhaust setups. Also keep in mind what I have said earlier about the stock eliminator class of drag racing. Those guys are incredibly fast and I know some of them are using reverse splits.

Thanks for keeping this civil and it has been good to have a discussion on the pro's and con's of this topic.