Anyone Interested in a Reverse Split Discussion
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
I'm also considering a RS cam. Just bought a 98 M6 Z28 and I'm planning on staying with the LS1 intake and installing the MAC mids I have lying around. I'm also planning on keeping the 3.42 gears so I'm actually looking for a cam that sounds/runs like stock and also [B]lowers[B] the peak where max HP occurs. I want to shift no higher than 5800-6000 RPM.
I was thinking of something like a 214/210 with .575+ lift on a 110 lsa. Would a cam like that sound and idle like a stocker Mr Predator?
I was thinking of something like a 214/210 with .575+ lift on a 110 lsa. Would a cam like that sound and idle like a stocker Mr Predator?
If I were you I would run more of a traditional split. Something like 214/220 112+1 LSA, -7 degree overlap so still stealth, 38 IVC for early peak.
Teching In
Joined: Nov 2010
Posts: 31
Likes: 0
From: LI, NY
Oh another question for you sir. Do all GM cams have the same lobes and thus ramp rates?
I would love to see a dyno comparison of 3 cams with the same specs as those of an LS1 cam but ground on XE, XER and XFI lobes.
I would love to see a dyno comparison of 3 cams with the same specs as those of an LS1 cam but ground on XE, XER and XFI lobes.
http://www.compcams.com/Technical/Ca...obeCatalog.pdf
Teching In
Joined: Nov 2010
Posts: 31
Likes: 0
From: LI, NY
You should look at the COMP lobe master catalog in the hydraulic roller section to get a decent idea of how Comp describes the lobes. I believe it goes xe, lxl, xfi, xe-r, ehi, lsl, lsk in that order for how aggressive the ramp rates are. The xe and lxl I believe are both single spring friendly with corresponding coil bind and the more aggressive the ramp rate the more valvetrain noise as well as stress on springs making them have a shorter life. The ramp rate and duration have nothing to do with head efficiency or intake manifold exhaust flow. The mid length headers are not much better than factory manifolds and thus require a conventional split and especially if you are still using cats.
http://www.compcams.com/Technical/Ca...obeCatalog.pdf
http://www.compcams.com/Technical/Ca...obeCatalog.pdf
https://ls1tech.com/forums/generatio...ock-motor.html
I don't know about the 5 RWHP thing when it comes to MAC mids. Plenty of guys have gotten 20+ and back in the day there were quite a few 10 sec cars running MACs.
https://ls1tech.com/forums/generatio...ock-motor.html
https://ls1tech.com/forums/generatio...ock-motor.html
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Verdad Gallardo TECH Senior Member
Joined: Mar 2004
Posts: 14,620
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From: BFE
The MACs Vs LTs is an old topic. IIRC they have shown similar flow in upper rpm but loose trq mid to low range. I ran them on my Z for 3 years but I had a custom Y with Flowmaster merge and had 3 catbacks. Stock, Hooker (best sounding at wot but drony) and Magnaflow (the most compromizing between performance and sound.
Teching In
Joined: Nov 2010
Posts: 31
Likes: 0
From: LI, NY
The MACs Vs LTs is an old topic. IIRC they have shown similar flow in upper rpm but loose trq mid to low range. I ran them on my Z for 3 years but I had a custom Y with Flowmaster merge and had 3 catbacks. Stock, Hooker (best sounding at wot but drony) and Magnaflow (the most compromizing between performance and sound.
Been looking at a lot of old threads and noticed that some of Lloyd Elliot's old cams were RS but now on his website all his cams are traditional split. Any reason for that or are the cams still RS due to using different lobes on the intake and exhaust?
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
You see, a cam functions with the help of all supporting mods. The parameters of the mods will make the cam behave in different ways.
The better the exhaust the more the RS will produce. (in general)
The better the exhaust the more the RS will produce. (in general)
Teching In
Joined: Nov 2010
Posts: 31
Likes: 0
From: LI, NY
Understood but what I don't understand is why you believe the exhaust will suffer by using MACs? Only reason why LTs make slightly more power is due to their added length and not because they flow more.
My plan is MACs with an H pipe going into true duals under the axle. There is no way a set of LTs with ORY going into any of the widely available Catbacks out there will make significantly more power. I would venture to say my exhaust would actually flow better and make more power.
My plan is MACs with an H pipe going into true duals under the axle. There is no way a set of LTs with ORY going into any of the widely available Catbacks out there will make significantly more power. I would venture to say my exhaust would actually flow better and make more power.
Understood but what I don't understand is why you believe the exhaust will suffer by using MACs? Only reason why LTs make slightly more power is due to their added length and not because they flow more.
My plan is MACs with an H pipe going into true duals under the axle. There is no way a set of LTs with ORY going into any of the widely available Catbacks out there will make significantly more power. I would venture to say my exhaust would actually flow better and make more power.
My plan is MACs with an H pipe going into true duals under the axle. There is no way a set of LTs with ORY going into any of the widely available Catbacks out there will make significantly more power. I would venture to say my exhaust would actually flow better and make more power.
When you get into exhaust theory from how I understand it long tubes are the only type of headers that provide that awesome exhaust scavenging effect that helps pull the exhaust gases out rather than just pushing them out with flow.
I will be the first to admit its really hard to not use free parts we already have but it just makes more sense with having your heart set on a reverse split to sell the mac headers and buy a decent set of the inexpensive mild steel long tubes and you likely could even find someone selling a used set.
I will be the first to admit its really hard to not use free parts we already have but it just makes more sense with having your heart set on a reverse split to sell the mac headers and buy a decent set of the inexpensive mild steel long tubes and you likely could even find someone selling a used set.
Teching In
Joined: Nov 2010
Posts: 31
Likes: 0
From: LI, NY
Aside from added cost, unfortunately most inexpensive LTs don't fit so great. I even had a set of Kooks on my former 02 Z28 and I had to grind the steering shaft knuckle and heat and massage one of the pipes for it to fit better and not rub.
Here's a track comparison between MACs and Edelbrock LTs. Now you will also notice that the header swap was not the only thing done for the car to pick up 3.5 MPH in the 1/4. I have a feeling that the addition of Trick Flow heads, bigger cam and a 90/90 intake helped more than going from Mids to LTs.
https://ls1tech.com/forums/drag-raci...nally-10s.html
https://ls1tech.com/forums/drag-raci...-1-8-mile.html
Here's a track comparison between MACs and Edelbrock LTs. Now you will also notice that the header swap was not the only thing done for the car to pick up 3.5 MPH in the 1/4. I have a feeling that the addition of Trick Flow heads, bigger cam and a 90/90 intake helped more than going from Mids to LTs.
https://ls1tech.com/forums/drag-raci...nally-10s.html
https://ls1tech.com/forums/drag-raci...-1-8-mile.html
Its too bad Edelbrock stopped making any exhaust products. I have a set of the Edelbrock stepped long tubes that were cheap and fit really great. I only had to grind the factory k-member a little and with my tubular k-member they have a factory like fitment just slip in.
[QUOTE=rubrick1;17686568]So then wouldn't using a RS cam be warranted to help bring the TQ up?
PRED is trying to get you to understand that the RS cam works when the exhaust is properly designed and is NOT a crutch for using the wrong header
Duals w/X pipe or 2 into 1 systems scavenge better for mid range torque
which is why they're popular in circle track applications
PRED is trying to get you to understand that the RS cam works when the exhaust is properly designed and is NOT a crutch for using the wrong header
Understood but what I don't understand is why you believe the exhaust will suffer by using MACs? Only reason why LTs make slightly more power is due to their added length and not because they flow more.
The added length has everything to do with why they work and I can tell ya
it's rather considerable (power improvement)
My plan is MACs with an H pipe going into true duals under the axle. There is no way a set of LTs with ORY going into any of the widely available Catbacks out there will make significantly more power. I would venture to say my exhaust would actually flow better and make more power.
The added length has everything to do with why they work and I can tell ya
it's rather considerable (power improvement)
My plan is MACs with an H pipe going into true duals under the axle. There is no way a set of LTs with ORY going into any of the widely available Catbacks out there will make significantly more power. I would venture to say my exhaust would actually flow better and make more power.
which is why they're popular in circle track applications
If fit was the main reason going against long tubes and money was not an issue I have heard the ARH 1 3/4" fit really well and they are only a few hundred more than a set of mild steel.