SVT Cams vs. 3.0L Cams: The Real Difference

[TennTechMan]

I mentioned in my "Preparing for a 3.0L Port-matched Swap" (http://www.contour.org/ceg-vb/showthread.php?t=40721) that I was going to do some measuring and comparing of the CSVT cams and the 3.0L cams. I did the measuring with an articulated arm coordinate measuring machine. After getting a scan of a pair of lobes from each cam, I over-layed them to really show the true differences between the cams. The cams I'm comparing are 2.5L cams from a 99 CSVT and 3.0L cams from a 2004 Taurus.

The only thing I am not 100% sure of is the timing (rotation) of the cams relative to each other. Each cam gear had a hole in it and a mark near the teeth on the front side of the gear. This hole and mark line up perfectly on each cam gear. Those features are what I used as a rotation reference when I overlayed the cams on the computer. Any comments on cam timing are based on this assumption.

Exhaust cam gear comparison: CSVT cam profile is green, 3.0L cam profile is black. Cam rotation is clock-wise.
SVT duration is longer
SVT opens sooner and closes at about the same time
Base circles are the same
Max lift is the same










Intake cam gear comparison: CSVT cam profile is green, 3.0L cam profile is black. Cam rotation is clock-wise.
SVT primary duration is about the same
SVT secondary duration is longer
SVT primary and secondary open sooner than 3.0L
SVT primary opens at faster rate
Base circles are the same
Max lift is the same

The biggest difference to me is cam timing. The SVT's advanced (relative to the 3.0L) cam timing shows that the SVT cams will build more power higher in the rpm range. The extra duration is also good. Duration is also notably longer on the SVT's exhaust cam and one lobe of the intake cam. The intake cam also opens faster to get more air in sooner. The cam with the largest area between its base circle and the cam profile above the base circle will flow the most air as long as it is timed correctly for where you want to make the power. For someone not tuning, I think the SVT cams especially make sence because the car is fuel-mapped for the higher-revving cams.

To sum it all up, the SVT cams are what will be going into the 3.0L swap I'm currently helping my brother with.

Over the next week, I will try to calculate the specs of each cam for those that prefer to compare cams that way.

 

[svttour]

Aaron

Thanks for this information. Its going to be really helpful. Im going to burn it into my brain. thumbs up!

 

[biminiLX]

Aaron:
Thank you very much for doing this and posting the information, much appreciated.
Any 3L I build will also have the the SVT cams.
-J

 

[Big Jim]

I think this shows what many of us have either know or suspected all along. The SVT cams have more potential. Getting that potential should be a matter of tuning as well as how well it is balanced with other mods.

 

[cannondalemtb]

Great post!

 

[95pgt-t]

sticky?

 

[TennTechMan]

I think this shows what many of us have either know or suspected all along. The SVT cams have more potential. Getting that potential should be a matter of tuning as well as how well it is balanced with other mods.

This is true of 3.0L swaps in anything other than an SVT car. In an SVT car, the ECU fuel maps are already tuned for the SVT cams. Putting the 3.0L cams in an un-tuned CSVT must be sluggish in the upper rpms.


I'm glad you guys like the info. I did it more for my own curiousity, but I couldn't help but share it since there's so much discussion about the choice.

 

[elraido]

This is true of 3.0L swaps in anything other than an SVT car. In an SVT car, the ECU fuel maps are already tuned for the SVT cams. Putting the 3.0L cams in an un-tuned CSVT must be sluggish in the upper rpms.


I'm glad you guys like the info. I did it more for my own curiousity, but I couldn't help but share it since there's so much discussion about the choice.

Are you saying put the 3.0L cams in a 2.5 engine or a 3.0L engine? I know 3.0L cams, from driving my car, they run out of power around 5.5K or so. In my old SVT it made power up until redline. BUT, even in my untuned 3.0L, the amount of power the 3.0L cams make in the lower part puts the svt cams to shame.....big time.

 

[SicSE]

In an SVT car, the ECU fuel maps are already tuned for the SVT cams. Putting the 3.0L cams in an un-tuned CSVT must be sluggish in the upper rpms.

I'm running 3L cams off an untuned SVT PCM in my hybrid, and sluggish is definitely not the word I would use to describe it's high-rpm performance. Power DOES drop off but it's not as bad as I've heard some people describe. Though, a lot of it could be dependant on setup, and mine is rather unique.

These graphs are sweet, BTW.

 

[turbo_fox]

Are you saying put the 3.0L cams in a 2.5 engine or a 3.0L engine? I know 3.0L cams, from driving my car, they run out of power around 5.5K or so. In my old SVT it made power up until redline. BUT, even in my untuned 3.0L, the amount of power the 3.0L cams make in the lower part puts the svt cams to shame.....big time.

could that low end power be a result of the 3L displacement rather than the cams? are you comparing the 3L cams in the 3L to the SVT cams in an svt engine or a 3L?

 

[elraido]

could that low end power be a result of the 3L displacement rather than the cams? are you comparing the 3L cams in the 3L to the SVT cams in an svt engine or a 3L?

Most posts that I have read say the same thing with a 3.0L with SVT cams and 3.0L cams. The low end power of the 3.0L cams is there where it is lacking in the SVT cams, while the top end the SVT cams shine while the 3.0L fall off.

Granted there is a difference in displacement between the 3.0L engine and the 2.5L engine. But, the way the two cars drive is so different that I can't just cough it up to displacement.

 

[turbo_fox]

Most posts that I have read say the same thing with a 3.0L with SVT cams and 3.0L cams. The low end power of the 3.0L cams is there where it is lacking in the SVT cams, while the top end the SVT cams shine while the 3.0L fall off.

Granted there is a difference in displacement between the 3.0L engine and the 2.5L engine. But, the way the two cars drive is so different that I can't just cough it up to displacement.

i understand what you are saying, but i was asking if your statement that the 3L cams "puts the svt cams to shame" is something from your own personal experience comparing 3L cams to SVT cams in a 3L, which it isnt- your own personal experience is comparing 3L to 2.5L.

I asked because my 3L with SVT cams pulls a ton better at low RPM as well, which is only due to the displacement. I am not convinced that SVT cams in a 3L makes less low end than the same 3L with 3L cams. I have never seen any data to back that up, especially since most people with 3L cams have 3L intakes as well

 

[elraido]

i understand what you are saying, but i was asking if your statement that the 3L cams "puts the svt cams to shame" is something from your own personal experience comparing 3L cams to SVT cams in a 3L, which it isnt- your own personal experience is comparing 3L to 2.5L.

I asked because my 3L with SVT cams pulls a ton better at low RPM as well, which is only due to the displacement. I am not convinced that SVT cams in a 3L makes less low end than the same 3L with 3L cams. I have never seen any data to back that up, especially since most people with 3L cams have 3L intakes as well

There is also a reason why Pud went this way in this car after what what he did with his last 3.0L (SVT heads etc). I am not saying one is better than the other, but there is a noticable difference in the way they drive.

 

[turbo_fox]

There is also a reason why Pud went this way in this car after what what he did with his last 3.0L (SVT heads etc). I am not saying one is better than the other, but there is a noticable difference in the way they drive.

right, I get that, you still are missing my point. it was not a change in cams only, so we have no comparison (other than the one at the top of the thread) between performance of SVT vs 3L cams on a 3L.

For example, I highly doubt I could swap from SVT cams to 3L cams in my ported 3L and gain any low end power. That isnt to say a full 3L wont make more low end power (such as yours), but I dont think the cams alone will make a low rpm difference- the noticeable difference you refer to has more to do with the 3L intakes.

 

[elraido]

right, I get that, you still are missing my point. it was not a change in cams only, so we have no comparison (other than the one at the top of the thread) between performance of SVT vs 3L cams on a 3L.

For example, I highly doubt I could swap from SVT cams to 3L cams in my ported 3L and gain any low end power. That isnt to say a full 3L wont make more low end power (such as yours), but I dont think the cams alone will make a low rpm difference- the noticeable difference you refer to has more to do with the 3L intakes.

I guess I was missing your point. :laugh: That helps to explain your arguement a little better.

 

[Rara]

First, thanks to TennTechMan for posting this up. Though I can't view the pics from work, its nice to ahve some more data put up to re-iterate what myself and several other people have been saying for quite some time.

One of the issues that cloud this whole discussion is that all the different experiences with the different cams are not consistant otherwise. Everyone has different intake setups, some are ported 3L heads w/ the SVT manifold, some are the '01 3.0L style intake, some are the later style 3L intake manifold, some are ST220, etc etc etc. plus each car has a different state of tune, some are untuned, some are properly tuned, and some are sort of better than untuned, but still not all that great, etc etc.

There are too many variables involved with all the anecdotal experiences to draw a reasonable conclusion from them. We need to focus on the data that is available, and where it isn't, draw from solid IC engine fundamentals to make educated guesses, and then test them where possible.

The timing and duration for the SVT cams clearly favor higher flow rates, especially at higher rpm, this would certainly explain the assumptions and anecdotal evidence of making power higher int he rev range. However, in order for the cams to be of any use at higher rpm, the intake manifold has to be able to support the airflow. In my educated opinion, I believe the stock SVT manifold (assuming split port all the way through) can flow enough air, and in the oval port camp, only the ST220 and the 04+ 3.0L plastic manifolds can support the higher airflow requirements optimally. Of course the new '09 escape UIM is there too. I don't believe that the increased compression ratio is the only reason the traditional hybrid 3.0L setups make good power all the way up to redline. (Granted, I have other issues with the hybrids, so I still don't recommend them in general)

As to the SVT cams being weaker in the mid range, it is possible to some extent, but I think that a large part of it is when people are running the SVT cams, and an oval port manifold (or the SVT w/ ported oval port heads) without the IMRC, and leaving the engine untuned, or not tuned by someone that knows the difference between timing maps for an engine w/ IMRC, and one w/ out IMRC. The IMRC keeps the velocity of the incoming air higher when the engine is at low rpm, and since all the air is coming through one port, it creates more tumble in the chamber, which requires different spark timing for optimal performance than if you simply have a single larger open port dumping into the chamber through both valves.

 

[TennTechMan]

Most posts that I have read say the same thing with a 3.0L with SVT cams and 3.0L cams. The low end power of the 3.0L cams is there where it is lacking in the SVT cams, while the top end the SVT cams shine while the 3.0L fall off.

I see this a lot also, but the trade-off is not equal. There is more to be gained from the SVT cams. My guess is that the 3.0L cams would only show more power/torque (at a given rpm) than the SVT cams below 2000 rpms.

 

[TennTechMan]

First, thanks to TennTechMan for posting this up. Though I can't view the pics from work, its nice to ahve some more data put up to re-iterate what myself and several other people have been saying for quite some time.

One of the issues that cloud this whole discussion is that all the different experiences with the different cams are not consistant otherwise. Everyone has different intake setups, some are ported 3L heads w/ the SVT manifold, some are the '01 3.0L style intake, some are the later style 3L intake manifold, some are ST220, etc etc etc. plus each car has a different state of tune, some are untuned, some are properly tuned, and some are sort of better than untuned, but still not all that great, etc etc.

There are too many variables involved with all the anecdotal experiences to draw a reasonable conclusion from them. We need to focus on the data that is available, and where it isn't, draw from solid IC engine fundamentals to make educated guesses, and then test them where possible.

The timing and duration for the SVT cams clearly favor higher flow rates, especially at higher rpm, this would certainly explain the assumptions and anecdotal evidence of making power higher int he rev range. However, in order for the cams to be of any use at higher rpm, the intake manifold has to be able to support the airflow. In my educated opinion, I believe the stock SVT manifold (assuming split port all the way through) can flow enough air, and in the oval port camp, only the ST220 and the 04+ 3.0L plastic manifolds can support the higher airflow requirements optimally. Of course the new '09 escape UIM is there too. I don't believe that the increased compression ratio is the only reason the traditional hybrid 3.0L setups make good power all the way up to redline. (Granted, I have other issues with the hybrids, so I still don't recommend them in general)

As to the SVT cams being weaker in the mid range, it is possible to some extent, but I think that a large part of it is when people are running the SVT cams, and an oval port manifold (or the SVT w/ ported oval port heads) without the IMRC, and leaving the engine untuned, or not tuned by someone that knows the difference between timing maps for an engine w/ IMRC, and one w/ out IMRC. The IMRC keeps the velocity of the incoming air higher when the engine is at low rpm, and since all the air is coming through one port, it creates more tumble in the chamber, which requires different spark timing for optimal performance than if you simply have a single larger open port dumping into the chamber through both valves.

Good input on the different intake manifolds giving different intake velocities. I have wondered how many of the Ford engineers that developed the SVT 2.5L would vomit on themselves to know that some people (myself included) are swapping in ported 3L's under their split-port dual runner intake manifold. My point is that they designed each intake runner to be isolated all the way to the combustion chamber, and we just un-isolate them.

Makes me think the hybrid option with lots of head work would be an ideal set-up. At least for someone wanting to retain the IMRC.

 

[biminiLX]

Makes me think the hybrid option with lots of head work would be an ideal set-up. At least for someone wanting to retain the IMRC.

This is close to what I think also. If you do some reading here on 'max-honed SVT UIM' and 'SHO-shop LIM' you can get some more info.
I'd say a mild port job on SVT heads (which allow about 11:1 compression), max-extrude honed SVT UIM and big-bore SVT LIM that retains the IMRC is the best 3L build.
I have an ST220 UIM which would be the best of the oval port options and I'm debating which way I'll be going.
Also, I totally understand what some of the "full 3L" guys say about average power, but what I personally want out of a 3L build would be the most average power from say 5000-7000+rpm. That would be the rpm range I'd be using during spirited driving. Any 3L low-end and lower mid-range would be better than we have with our 2.5L SVTs and even the stock output is fine with me for the daily grind. It's when I hit the throttle I want the most power possible and if that means having to downshift to get to 5000rpm that's fine with me.
Anyway, thats my 2 cents.
-J

 

[Pudmunkie]

I'm drunk so im going to keep this quick....

3 liter cams > SVT cams. Ive had both and I really don't give a what the reason is.... 3 liter cams in a full 3 liter own.