JDM SS cams and driveability

RioRed4v

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Question regarding these cams and driveability. I've read mixed results on how street friendly these things are and was hoping I could get some feedback.

I purchased an 09 GT500 with a built engine that has these cams and a KB 3.6 on it. At low rpm's (like leaving a light) the cars feels like it loads up/sputters and then finally drives normal once the rpm's come up a bit. I was wondering if this was a characteristic of the cams, or if maybe the the tune in it is off?
 

Catmonkey

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That's the nature of increased duration, overlap and low idle vacuum. Tuning can help, but it will never drive like it did with stock cams and won't be happy under 2,000 rpm under light throttle/cruise.
 

RedVenom48

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Question regarding these cams and driveability. I've read mixed results on how street friendly these things are and was hoping I could get some feedback.

I purchased an 09 GT500 with a built engine that has these cams and a KB 3.6 on it. At low rpm's (like leaving a light) the cars feels like it loads up/sputters and then finally drives normal once the rpm's come up a bit. I was wondering if this was a characteristic of the cams, or if maybe the the tune in it is off?

Totally normal for high lift/duration cams.

The idea behind the factory camshafts is to give good performance off idle up to near factory redline while remaining emissions compliant. Performance camshafts alter when and how the intake air flows into the combustion chamber. An old saying of "Getting it up on the cam" still applies. Cams typically need higher engine RPM to work.

You probably have crazy airflow from 2000-7000 RPM now, most especially when in boost. :D

Unless its a Daily Driver, Id leave them in and enjoy the performance benefits for what they are. Or.. you know... I could pull my factory cams out and we could swap... :D :D :D
 

Catmonkey

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However, if the car is not tuned for those cams, it will be a lot more unpleasant to drive than having it tuned appropriately for those cams. I'm not sure what camp you're in without more info or physically driving your car.
 

RedVenom48

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However, if the car is not tuned for those cams, it will be a lot more unpleasant to drive than having it tuned appropriately for those cams. I'm not sure what camp you're in without more info or physically driving your car.
Very true, we can only assume that OP's car is tuned. @RioRed4v , did the seller state who tuned the car?
 

RioRed4v

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Thanks guys for the input. Definitely reminds me of one of my old fox-body cars that had a big cam in (unfortunately lol). It's not terrible, just a little bit annoying and luckily the car is just a weekend cruiser.

The shop that built the car and tuned is a pretty highly regarded one (triangle speed shop) so I'm not really doubting the work, just trying to get a better idea if it was normal.

The car has 3.55 gears, do you think 3.73's might help it out a little?

Oh, and @lexustech48 yea, the air flow is insane from what it feels like. Car pulls like a damn freight train once it hits boost lol. You mentioned emissions with these cams - Any idea how bad they when it comes to emissions? The guy told me it'll pass especially with it being E85.

@Catmonkey the idle vacuum i'm seeing is right about 15hg. Seem normal?
 

Catmonkey

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15inhg seems pretty high for the JDM cams. I would expect 6-8inhg. I've got milder cams than those and have 13inhg. What is the idle speed set at? 16inhg at idle is generally regarded as the goal for decent street manners. My car doesn't like cruise/light throttle below 1,600 rpm. You have the benefit of lower 5th and 6th gears than the 10-12, so 3.73s should work. Personally, I may go to 4.10s at some point, but I have a 2013 transmission without that really low first gear.
 

RioRed4v

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15inhg seems pretty high for the JDM cams. I would expect 6-8inhg. I've got milder cams than those and have 13inhg. What is the idle speed set at? 16inhg at idle is generally regarded as the goal for decent street manners. My car doesn't like cruise/light throttle below 1,600 rpm. You have the benefit of lower 5th and 6th gears than the 10-12, so 3.73s should work. Personally, I may go to 4.10s at some point, but I have a 2013 transmission without that really low first gear.

I've only driven the car once so far since getting it, but if I recall the idle speed was right around 850-900.

I was reading to help with idle vacuum there is the L&M low vaccum bypass, makes me wonder if it has one of those to help with idle vacuum.
 

Catmonkey

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The low vacuum bypass doesn't really do anything to improve idle, it has a lower power spring to let low vacuum open the bypass at idle and lower engine speeds. It takes somewhere around 12 inhg to open the valve. I'm on the edge of needing one of those on my car. I've got my idle set at 850 rpm. It's just a bit happier at that speed than anything I've tried that was lower. Especially with the a/c on.
 

RedVenom48

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15inhg seems pretty high for the JDM cams. I would expect 6-8inhg. I've got milder cams than those and have 13inhg. What is the idle speed set at? 16inhg at idle is generally regarded as the goal for decent street manners. My car doesn't like cruise/light throttle below 1,600 rpm. You have the benefit of lower 5th and 6th gears than the 10-12, so 3.73s should work. Personally, I may go to 4.10s at some point, but I have a 2013 transmission without that really low first gear.
Ive got the 2.97:1 first with 4.10s.... its uh... rowdy. :) Well, at least when it hooks lol
 

RioRed4v

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The low vacuum bypass doesn't really do anything to improve idle, it has a lower power spring to let low vacuum open the bypass at idle and lower engine speeds. It takes somewhere around 12 inhg to open the valve. I'm on the edge of needing one of those on my car. I've got my idle set at 850 rpm. It's just a bit happier at that speed than anything I've tried that was lower. Especially with the a/c on.

Ah, that makes sense. Thanks! Still very new to this platform and trying to soak up as much as possible especially with having already bought a car as built as this one.
 

genesmob

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I have fully built motor with JDM ss cams and a whipple 4.0. It’s a great package that works better than they advertise. I have idle set at 750 rpm and experience perfect driveability with no hesitation or cruise issues. I would bet your problem has to do with a large Maf tube (required) and the low resolution at idle that comes with it. I tune my own car and have found with large maf tubes (149-155mm) you have to find a happy medium at low maf voltages (idle and low load cruise) You probably need some fine tuning of your maf curve. To check this I would datalog maf voltage and short term fuel trims while replicating this problem. If there are large stft swings and you notice maf voltage is the same or less at idle as it is at low load cruise, this is it. Ideally maf voltage should always increase as rpm and load rises. When the tube dia increases, the air velocity goes down sometimes causing inaccurate readings at low airflow.


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RioRed4v

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I have fully built motor with JDM ss cams and a whipple 4.0. It’s a great package that works better than they advertise. I have idle set at 750 rpm and experience perfect driveability with no hesitation or cruise issues. I would bet your problem has to do with a large Maf tube (required) and the low resolution at idle that comes with it. I tune my own car and have found with large maf tubes (149-155mm) you have to find a happy medium at low maf voltages (idle and low load cruise. You probably need some fine tuning of your maf curve. To check this I would datalog maf voltage and short term fuel trims while replicating this problem. If there are large stft swings and you notice maf voltage is the same or less at idle as it is at low load cruise, this is it. Ideally maf voltage should always increase as rpm and load rises. When the tube dia increases, the air velocity goes down sometimes causing inaccurate readings at low airflow.


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Interesting. I mean, if I get the driveability to be even close to perfect that would be awesome.

When you do your tuning is done on the street, or dyno? Does it even matter? Do you tune with SCT?

I've been talking with a local shop to have them diagnose the tune and am hoping they can find something, but I'm not too hopeful with the mixed results I've read about the cams.
 

RBB

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I run SS cams with 3.73s, idle at 850, and don’t really have any issues. It’s definitely not as smooth as stock at low speeds, but that’s to be expected.

Combined with a grabby aftermarket clutch that holds a lot of torque, which I’m assuming you have, you need to give it some more RPMs when taking off from a stop. It took a little time to get used to.
 

genesmob

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Interesting. I mean, if I get the driveability to be even close to perfect that would be awesome.

When you do your tuning is done on the street, or dyno? Does it even matter? Do you tune with SCT?

I've been talking with a local shop to have them diagnose the tune and am hoping they can find something, but I'm not too hopeful with the mixed results I've read about the cams.[/



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I use Hp tuners and do most of the tuning on the street
 

RedVenom48

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Interesting. I mean, if I get the driveability to be even close to perfect that would be awesome.

When you do your tuning is done on the street, or dyno? Does it even matter? Do you tune with SCT?

I've been talking with a local shop to have them diagnose the tune and am hoping they can find something, but I'm not too hopeful with the mixed results I've read about the cams.
.
& when I mention tuning on the street, people act like I'm speaking a foreign language..
+1

One of the reasons Ive stuck with Lund is that part of the initial tuning process is running the car on the street to grab a data log. Real world conditions under real load will always beat a dyno for driveability
 

biminiLX

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I run SS cams with 3.73s, idle at 850, and don’t really have any issues. It’s definitely not as smooth as stock at low speeds, but that’s to be expected.

Combined with a grabby aftermarket clutch that holds a lot of torque, which I’m assuming you have, you need to give it some more RPMs when taking off from a stop. It took a little time to get used to.
Same here.
I can cruise in 6th at 1500rpm no issues with the JDM SS cams. I did need a low vacuum bypass
-J
 

tvspower

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I still can not understand why, when, where, anybody would drive these cars under 2000rpm.......
 

RBB

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Same here.
I can cruise in 6th at 1500rpm no issues with the JDM SS cams. I did need a low vacuum bypass
-J
You’ve got 4.10s right? 1500 is a little rough for me with 3.73s, need a couple hundred more rpms for good cruising.

I installed a low vacuum bypass as well. Idle vacuum is about 10inhg.
 

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