What cams to use for a built motor with greddy TT?
05-02-2009, 08:53 PM
#41
The idle is loopey, but not to bad my idle is set at 1000rpms though.
I like a rough loopey idle though, I think I am actually going to lower the idle a bit so it is even more loopey.
I don't remember the overlap off the top of my head, I will check for you when I get back into the shop on monday.
Also we were running conservative timing on the top end of my car on that run, if not it would have kept making power.
-George
GT Motorsports
I like a rough loopey idle though, I think I am actually going to lower the idle a bit so it is even more loopey.
I don't remember the overlap off the top of my head, I will check for you when I get back into the shop on monday.
Also we were running conservative timing on the top end of my car on that run, if not it would have kept making power.
-George
GT Motorsports
05-02-2009, 09:55 PM
#42
The idle is loopey, but not to bad my idle is set at 1000rpms though.
I like a rough loopey idle though, I think I am actually going to lower the idle a bit so it is even more loopey.
I don't remember the overlap off the top of my head, I will check for you when I get back into the shop on monday.
Also we were running conservative timing on the top end of my car on that run, if not it would have kept making power.
-George
GT Motorsports
I like a rough loopey idle though, I think I am actually going to lower the idle a bit so it is even more loopey.
I don't remember the overlap off the top of my head, I will check for you when I get back into the shop on monday.
Also we were running conservative timing on the top end of my car on that run, if not it would have kept making power.
-George
GT Motorsports
05-02-2009, 09:59 PM
#43
The idle is loopey, but not to bad my idle is set at 1000rpms though.
I like a rough loopey idle though, I think I am actually going to lower the idle a bit so it is even more loopey.
I don't remember the overlap off the top of my head, I will check for you when I get back into the shop on monday.
Also we were running conservative timing on the top end of my car on that run, if not it would have kept making power.
-George
GT Motorsports
I like a rough loopey idle though, I think I am actually going to lower the idle a bit so it is even more loopey.
I don't remember the overlap off the top of my head, I will check for you when I get back into the shop on monday.
Also we were running conservative timing on the top end of my car on that run, if not it would have kept making power.
-George
GT Motorsports
In this thread I would like to provide the various cam profiles that are available - Stage 2 and Up.
Last edited by ttg35fort; 05-02-2009 at 10:02 PM.
05-03-2009, 07:35 AM
#49
Registered User
Thread Starter
iTrader: (52)
Join Date: Mar 2007
Location: NJ/NY
Posts: 913
Likes: 0
Received 0 Likes
on
0 Posts
hmm wow thanks for the info guys.
Ok for my build for my 04.5 Z..
ENGINE:
G35 rev up short block
high speed crank balance
arias ed 9:1 pistons
eagle rods
ACL or cosworth bearings (rod, main, thrust)
HR oil pump
ARP main studs
ARP head studs (might need L19's)
Cosworth or Cometic head gasket
HEADS
port and polish non rev up heads
3 angle valve job
HR valve springs (double shimming)
BC2 or JTW C2 cams
My goal is to hit ~600whp with greddy twins
Are the stock I/E valves ok to use for this power level?
Ok for my build for my 04.5 Z..
ENGINE:
G35 rev up short block
high speed crank balance
arias ed 9:1 pistons
eagle rods
ACL or cosworth bearings (rod, main, thrust)
HR oil pump
ARP main studs
ARP head studs (might need L19's)
Cosworth or Cometic head gasket
HEADS
port and polish non rev up heads
3 angle valve job
HR valve springs (double shimming)
BC2 or JTW C2 cams
My goal is to hit ~600whp with greddy twins
Are the stock I/E valves ok to use for this power level?
05-03-2009, 10:17 AM
#53
Former Sponsor
iTrader: (564)
Join Date: Feb 2003
Location: Long Island, New York
Posts: 19,266
Likes: 0
Received 5 Likes
on
5 Posts
that's why ecu's that allow cam timing changes are worthwhile - makes the "big" cam idle like a smaller one
05-03-2009, 10:59 AM
#54
OK, I did some research on cams and below I provide a brief summary based on this research. This should be useful for anyone selecting new cams. When selecting cams, there is always some sort of compromise that is made with different cam profiles. The key is to select the cam profile with the least amount of compromise for your particular goals while capturing the greatest amount of performance increases.
Duration
With regard to duration, the most significant impact on performance is the 0.050" duration specification. For the most part, the advance duration specification is meaningless other than providing an indication of the front and rear lobe profile. Specifically, the difference between the advanced duration and the 0.050" duration can provide an indication of how steep the cam lobe profile is, which also generally relates to the amount of lift provided. In other words, high lift cams generally have a smaller difference between the advance duration and 0.050" duration in comparison to cams with less lift.
Generally speaking, given two cams with the same lift, at high rpm the cam with a longer 0.050" duration will provide better volumetric efficiency (VE) than a cam with a shorter 0.050" duration, and thus provide more power, regardless of their respective advanced durations. Hi duration cams, however, generally do not perform as well as low duration cams in the low-mid rpm range due to overlap between the intake valve opening and the exhaust valve closing. In a turbo motor, there tends to be higher exhaust back pressure in comparison to a naturally aspirated motor. Thus, when turbo motors have valve overlap, they are more prone to reversion of the exhaust gases, depending on the ratio of the exhaust pressure/intake pressure . Typically, you do not want this ratio to exceed 1.5:1. If it exceeds this ratio, you may need bigger turbo housings to reduce the exhaust back pressure.
The duration of a cam is based on the intake and exhaust valve opening and closing events. Higher duration cams provide a greater amount of overlap in comparison to lower duration cams. There are two regions of valve overlap, namely bottom dead center (BDC) between the combustion stroke and the exhaust stroke, and top dead center (TDC) between the exhaust stroke and intake stroke.
For an exhaust valve, a late valve closing event will typically provide greater high rpm power while sacrificing some low rpm torque/power in comparison to an earlier exhaust valve closing. Similarly, an early exhaust valve opening will typically provide greater high rpm power while sacrificing some low rpm torque/power. That said, assuming a reasonable valve opening point is used, the exhaust valve closing event generally has a greater impact on engine performance than the exhaust valve opening event.
For an intake valve, an earlier valve opening event generally provides better high rpm performance in comparison to a later valve opening event, but again at the sacrifice of some low rpm torque/power.
Variable valve timing is used to advance and retard the opening and closing events. In a VQ35DE, for example, the intake cams are advanced in the low-mid rpm to provide better low-mid RPM power, and then retarded back toward 0 degrees as the rpms increase. The VQ37HR motors apply variable valve timing to both the intake and exhaust valves.
Lift
With regard to lift, if two cams have the same 0.050" duration and valve opening/closing points, but one has higher lift, the cam with the higher lift will provide better VE, and thus more power throughout the rpm band, but the idle characteristics of the two cams should be about the same.
However, given the same valve train and springs, the lower lift cam should be able to operate at higher rpm than the higher lift cam. In particular, the cam with less lift typically will be less prone to the bucket (on the top of the valve spring) "ski jumping" off the cam lobe after passing the maximum lift point (a.k.a. valve float) because there is less angle on the back portion of the cam lobe. Accordingly, the valve springs for a higher lift cam should have a higher spring rate and/or lighter valves for extremely high rpm operation. There are some cams designed with different front and back profiles for the lobes, which should help alleviate some of this issue, though I don't know whether any VQ cams are designed this way.
Cam Selection
For proper cam selection, one should do the following:
1. For your engine, determine a suitable 0.050" overlap that achieves the greatest 0.050” duration, while still providing idle and low-mid rpm characteristics that you are looking for. Remember, a cam with a larger 0.050" overlap will generally require a higher idle rpm to achieve the same idle characteristics as a cam with less 0.050" overlap, and a larger overlap generally will provide less low-mid rpm power. Based on the amount of overlap, identify cams with this overlap and their respective 0.050" durations.
Although valve overlap needs be taken into consideration, at this point we only have valve overlap data on the JWT cams. So, for the remainder of this analysis, I am ignoring valve overlaps and assuming they are the same for cams with equivalent duration. This likely is not the case, but I am working with the data I presently have available.
Also, if you used forced induction, this also should be taken into consideration. When turbos are used, there is more exhaust back pressure, and hence the scavaging affect is less in the lower rpms before the turbos are spooled up. Once the turbos are spooled up, and the intake pressure exceeds the exhaust back pressure, the opposite occurs as the pressurized intake charge can help push out the exhaust charge.
2. Once you have identified cams with a particular 0.050" overlap and noted their durations, determine the maximum rpm the engine will be running at, and then select the cam/springs/valve combination that will provide the greatest amount of lift and that is safety operable at your maximum rpm. In illustration, if you will be running your engine to 9500 rpm, you will probably want to go with a cam that has lower lift (i.e., less front and rear angle on the lobes) in comparison an engine that will be running to 7500 rpm.
Examples
Now, I'll examine my new GTM 4.0L stroker motor as an example. I don’t mind a slightly lopey idle, but I don’t want to sacrifice so much low rpm power that it significantly degrades daily driving performance. My JWT C2 cams have 26 degrees of overlap (8 deg. at 0.050" lift) and a duration of 225 degrees at 0.050”, but I think I could live with a little more overlap if that means getting more duration and lift. Thus, I’m leaning toward a cam with another 10 degrees or so of duration, and probably a corresponding increase in overlap. Of the choices listed on the previous page of this thread, that would be the GTM Stage 2 cams, the BC Stage 3 cams, or the JWT C8 cams.
Per Sam, this motor should be good to about 7500 rpm. Per JWT, the C8 cams are good to about 7300 - 7500 rpm when using the JWT valve springs and stock valves. I have Ferrea valves, however, which extends the safe rpm range for these cams to over 7500 rpm. So this cam/spring/valve combination is a good choice for my new build. In addition, the JWT C8 cams provide the greatest amount of lift of the cams noted above, and thus would provide the most VE and power.
On the otherhand, the GTM 3.8L stroker motor is good to run in excess of 8500 rpm. Thus, for this motor, the JWT C8 cams probably would not be a good choice; a cam with less front and back lobe angles should be used to deal with the higher rpm. In other words, for the same 0.050" duration, a cam with a lower lift should be used. If I were building this motor, I would look at the GTM Stage 2 cams, the BC Stage 3 cams, and the GTM Stage 3 cams. If I could live with the lopey idle of the GTM Stage 3 cams, I would go with them. If not, I would go with the BC Stage 3 cams. The GTM Stage 3 cams will provide the best top end performance, while the BC Stage 3 cams will idle smoother and provide better low-mid rpm power.
Duration
With regard to duration, the most significant impact on performance is the 0.050" duration specification. For the most part, the advance duration specification is meaningless other than providing an indication of the front and rear lobe profile. Specifically, the difference between the advanced duration and the 0.050" duration can provide an indication of how steep the cam lobe profile is, which also generally relates to the amount of lift provided. In other words, high lift cams generally have a smaller difference between the advance duration and 0.050" duration in comparison to cams with less lift.
Generally speaking, given two cams with the same lift, at high rpm the cam with a longer 0.050" duration will provide better volumetric efficiency (VE) than a cam with a shorter 0.050" duration, and thus provide more power, regardless of their respective advanced durations. Hi duration cams, however, generally do not perform as well as low duration cams in the low-mid rpm range due to overlap between the intake valve opening and the exhaust valve closing. In a turbo motor, there tends to be higher exhaust back pressure in comparison to a naturally aspirated motor. Thus, when turbo motors have valve overlap, they are more prone to reversion of the exhaust gases, depending on the ratio of the exhaust pressure/intake pressure . Typically, you do not want this ratio to exceed 1.5:1. If it exceeds this ratio, you may need bigger turbo housings to reduce the exhaust back pressure.
The duration of a cam is based on the intake and exhaust valve opening and closing events. Higher duration cams provide a greater amount of overlap in comparison to lower duration cams. There are two regions of valve overlap, namely bottom dead center (BDC) between the combustion stroke and the exhaust stroke, and top dead center (TDC) between the exhaust stroke and intake stroke.
For an exhaust valve, a late valve closing event will typically provide greater high rpm power while sacrificing some low rpm torque/power in comparison to an earlier exhaust valve closing. Similarly, an early exhaust valve opening will typically provide greater high rpm power while sacrificing some low rpm torque/power. That said, assuming a reasonable valve opening point is used, the exhaust valve closing event generally has a greater impact on engine performance than the exhaust valve opening event.
For an intake valve, an earlier valve opening event generally provides better high rpm performance in comparison to a later valve opening event, but again at the sacrifice of some low rpm torque/power.
Variable valve timing is used to advance and retard the opening and closing events. In a VQ35DE, for example, the intake cams are advanced in the low-mid rpm to provide better low-mid RPM power, and then retarded back toward 0 degrees as the rpms increase. The VQ37HR motors apply variable valve timing to both the intake and exhaust valves.
Lift
With regard to lift, if two cams have the same 0.050" duration and valve opening/closing points, but one has higher lift, the cam with the higher lift will provide better VE, and thus more power throughout the rpm band, but the idle characteristics of the two cams should be about the same.
However, given the same valve train and springs, the lower lift cam should be able to operate at higher rpm than the higher lift cam. In particular, the cam with less lift typically will be less prone to the bucket (on the top of the valve spring) "ski jumping" off the cam lobe after passing the maximum lift point (a.k.a. valve float) because there is less angle on the back portion of the cam lobe. Accordingly, the valve springs for a higher lift cam should have a higher spring rate and/or lighter valves for extremely high rpm operation. There are some cams designed with different front and back profiles for the lobes, which should help alleviate some of this issue, though I don't know whether any VQ cams are designed this way.
Cam Selection
For proper cam selection, one should do the following:
1. For your engine, determine a suitable 0.050" overlap that achieves the greatest 0.050” duration, while still providing idle and low-mid rpm characteristics that you are looking for. Remember, a cam with a larger 0.050" overlap will generally require a higher idle rpm to achieve the same idle characteristics as a cam with less 0.050" overlap, and a larger overlap generally will provide less low-mid rpm power. Based on the amount of overlap, identify cams with this overlap and their respective 0.050" durations.
Although valve overlap needs be taken into consideration, at this point we only have valve overlap data on the JWT cams. So, for the remainder of this analysis, I am ignoring valve overlaps and assuming they are the same for cams with equivalent duration. This likely is not the case, but I am working with the data I presently have available.
Also, if you used forced induction, this also should be taken into consideration. When turbos are used, there is more exhaust back pressure, and hence the scavaging affect is less in the lower rpms before the turbos are spooled up. Once the turbos are spooled up, and the intake pressure exceeds the exhaust back pressure, the opposite occurs as the pressurized intake charge can help push out the exhaust charge.
2. Once you have identified cams with a particular 0.050" overlap and noted their durations, determine the maximum rpm the engine will be running at, and then select the cam/springs/valve combination that will provide the greatest amount of lift and that is safety operable at your maximum rpm. In illustration, if you will be running your engine to 9500 rpm, you will probably want to go with a cam that has lower lift (i.e., less front and rear angle on the lobes) in comparison an engine that will be running to 7500 rpm.
Examples
Now, I'll examine my new GTM 4.0L stroker motor as an example. I don’t mind a slightly lopey idle, but I don’t want to sacrifice so much low rpm power that it significantly degrades daily driving performance. My JWT C2 cams have 26 degrees of overlap (8 deg. at 0.050" lift) and a duration of 225 degrees at 0.050”, but I think I could live with a little more overlap if that means getting more duration and lift. Thus, I’m leaning toward a cam with another 10 degrees or so of duration, and probably a corresponding increase in overlap. Of the choices listed on the previous page of this thread, that would be the GTM Stage 2 cams, the BC Stage 3 cams, or the JWT C8 cams.
Per Sam, this motor should be good to about 7500 rpm. Per JWT, the C8 cams are good to about 7300 - 7500 rpm when using the JWT valve springs and stock valves. I have Ferrea valves, however, which extends the safe rpm range for these cams to over 7500 rpm. So this cam/spring/valve combination is a good choice for my new build. In addition, the JWT C8 cams provide the greatest amount of lift of the cams noted above, and thus would provide the most VE and power.
On the otherhand, the GTM 3.8L stroker motor is good to run in excess of 8500 rpm. Thus, for this motor, the JWT C8 cams probably would not be a good choice; a cam with less front and back lobe angles should be used to deal with the higher rpm. In other words, for the same 0.050" duration, a cam with a lower lift should be used. If I were building this motor, I would look at the GTM Stage 2 cams, the BC Stage 3 cams, and the GTM Stage 3 cams. If I could live with the lopey idle of the GTM Stage 3 cams, I would go with them. If not, I would go with the BC Stage 3 cams. The GTM Stage 3 cams will provide the best top end performance, while the BC Stage 3 cams will idle smoother and provide better low-mid rpm power.
Last edited by ttg35fort; 05-06-2009 at 11:06 AM.
to that kid that got banned for questioning me..stupid noob
05-03-2009, 11:29 AM
#57
I get sick of reading, get xxxx because it is the best FTFMW, when the guys saying this stuff oftentimes have absolutely no clue about what they are talking about. It really makes it difficult for Noobs, or anybody else for that matter, who are willing to do the research in the forum to find the correct answers to their questions. As far as the Newbies who are too lazy to search, well I let the rest of the crew handle that.
We really need more data on the BC and GTM cams in order for people to really be able to evaluate which cams are best for their particular builds. Hopefully George will come through for me. If not, I'll call sam next week.
If anybody has the intake and exhaust opening angles, as well as the overlap of the BC cams, or any other performance cams likely to be used by those of us in FI, please post it hear or PM me so I can update the table in post 39.
Last edited by ttg35fort; 05-03-2009 at 11:51 AM.
05-03-2009, 11:36 AM
#59
Banned
iTrader: (21)
Join Date: Dec 2003
Location: Florida
Posts: 4,472
Likes: 0
Received 0 Likes
on
0 Posts
^ +1 ^ I should of clarified that "my cams are the best" for my goals and particular setup. Terry, I really think you will be happy with the C8's based on your setup... I find it kind of cool when my car is idling and some one says "what cams you got it in there"
05-03-2009, 01:09 PM
#60
hmm wow thanks for the info guys.
Ok for my build for my 04.5 Z..
ENGINE:
G35 rev up short block
high speed crank balance
arias ed 9:1 pistons
eagle rods
ACL or cosworth bearings (rod, main, thrust)
HR oil pump
ARP main studs
ARP head studs (might need L19's)
Cosworth or Cometic head gasket
HEADS
port and polish non rev up heads
3 angle valve job
HR valve springs (double shimming)
BC2 or JTW C2 cams
My goal is to hit ~600whp with greddy twins
Are the stock I/E valves ok to use for this power level?
Ok for my build for my 04.5 Z..
ENGINE:
G35 rev up short block
high speed crank balance
arias ed 9:1 pistons
eagle rods
ACL or cosworth bearings (rod, main, thrust)
HR oil pump
ARP main studs
ARP head studs (might need L19's)
Cosworth or Cometic head gasket
HEADS
port and polish non rev up heads
3 angle valve job
HR valve springs (double shimming)
BC2 or JTW C2 cams
My goal is to hit ~600whp with greddy twins
Are the stock I/E valves ok to use for this power level?
Please DO NOT use the Cometic headgasket. There have been problems with these on VQ motors. I can't opine about the Cosworth head gaskets because I don't know anybody who has ran them.
Do yourself a favor and seriously look into using the HR head gaskets or the HKS head gaskets. After speaking in depth about this issue both with Jim Wolf and Sam at GTM, as well as some other forum members, I'm using HR gaskets on my motor. I'll be pushing 700 RWHP on pump gas, and well over that with meth injection on line. FYI, the HR head gaskets cost about $60 - $70, whereas the HKS headgaskets cost $360. Nonetheless, you can't go wrong with HKS headgaskets. I have never heard of one failing on a build without aftermarket sleeves. The problems when aftermarket sleeves were used were due to the sleeves moving, not the gaskets.
Cams
What will your maximum RPM be? That will determine which cam is best for you. MAKE SURE YOU GET REV UP VERSIONS OF THESE CAMS IF YOU ARE USING A REV UP HEAD!!! The VQ35DE cams may not work.
If it will be less that 7500 rpm, (Scratch the C2's, SmallTuner reminded me, in a very polite way I might add, that you are using RevUp Heads). Look at the JWT S7R's and C8R's. You must use the JWT springs with these. They are harmonically balanced for the JWT cam profiles. I'll post their specifications in the previous page. Edit: After posting their respective specifications, I see that they both have minimum overlap. Hence, I would go with the C8Rs.
If you will be reving over 7500 RPM, BC or GTM cams. However, on the Brian Crower site, I did not see any RevUp cams listed. GTM has Stage 1, Stage 2 and Stage 3 cams for the Rev Up motor. So far, the specifications look the same as the non-RevUp motors. For high RPM use, I believe the GTM cams are the ticket.
Valves
The power level is not a problem for the stock valves, but you might want to check to see what RPM they are good to. If the conclusion is that they aren't good for the RPM you will be pushing and you need aftermarket valves, you cannot go wrong with Ferrea valves. I'm sure there are other good valves out there too, but stay away from BC valves. I have heard of them breaking when pushed hard.
Port and Polishing
As far as port and polishing, I would only MATCH port if keeping the rpms under 7500. When you open up the ports beyond that, you start to lose low-mid rpm performance. If, however, you will be pushing over 7500 rpms, then increasing the size of the ports will again help at those high rpms.
Pistons
I would recommend slightly less compression than 9.0:1 if you want to achieve 600 RWHP on pump gas. Otherwise, pre-detonation may become an issue before you get to that level (unless your using meth injection or testing on a DynoJet
). Try to use something in the range of 8.5:1 to 8.8:1.On my new build, I have specifically requested Wisecos, even though the motor will cost me the same $$$ regardless of whether I use Wisco or Arias. Moreover, Sam is concerned that the Wiseco's will not arrive fast enough since they are custom made for that motor, so I asked him to offer Wiseco an expedite fee to try to get them there on time. I would rather pay a little more and know that I have the Wisecos. In your case, the Wisecos are less expensive than Arias but, in my humble opinion (based upon a lot of research I might add), I prefer them to Arias and some other pistons. CP's also are supposed to be very good, but JetPilot is the only one I know running them. You might look into those as well.
Other Stuff
Everything else looks OK, but you also will need alot of other parts.
For example, you will need a wastegate relocation kit to keep the Greddy's boost from creeping at the boost levels you will need to get to 600 RWHP. Boost creep in the Greddy's can cause some serious issues at those boost levels.
You will need a clutch strong enough to hold the power if you have a manual, or upgrade your transmission with new clutch packs, etc., if you have an automatic. If you have a manual, go with a multi-disk clutch. I started with a twin disk Clutchasters FX600, but it didn't hold up for me. Now I have a Carbonetics triple disk. It is much, much stronger and much, much smoother for street driving than the clutchmasters. Each plate on the Carbonetics has probably double the surface area of the Clutchmasters. Exedy and GTM also are supposed to have good clutches, but I have never driven a car that has them, so I can't provide a comparison to the clutches I have used.
You also will need an EMS (HKS F-CON and Haltech are popular choices), a dual exhaust system 2.75" dia. or bigger, downpipes, a fuel return system, larger fuel injectors, a plenum spacer if using your stock plenum, a larger radiator, etc. An oil cooler or two also would be good, as well as a suitably sized oil catch can.
Last edited by ttg35fort; 05-03-2009 at 04:09 PM.