Computer controlled cam

[REM777]

You've obviously never owned one of these trucks with a 109 LSA. Maybe a donkey dick cam would be difficult, but not the wee little cams we're talking about.

the "tuning hell" was the cost of the computer upgrade because the pre-1998 computers are obsolete as far as the tuning world is concerned. Sure you can tune them, but the cost and scarcity starts making it of questionable economics. Look at the insano quotes for some mailorder tunes like blackbear -their cost justification centers around a computer that requires hard to find EFI Live dongles. Same with other tuners with the archiac Jet Performance tuning envioment. Agree we are talking wee cams here, but wee cams+ make a stock vehicle run like sh__ off the rack. Look at all the jim-crackery that L31Express had to do to make his 109 LSA work .. IE rhodes lifters. My point is 1) drop in cam drive and forget cam, 2) nice performance upgrade and 3) over .500 lift is a waste given the limitations of the vortec head SANS porting.

 

[L31MaxExpress]

Well, you said " . . Rhoads V-Max lifters tame the thing around idle to the point it pulls 18 in/hg @ 650 rpm. The rhoads lifters make the cam smaller on the low-end but the full duration and lift extend the powerband above 4,000 rpm. With them I was able to bump the cam size for more power but still have the manners and off-idle torque of a smaller cam. . . " So you have a little more going on here than JUST the 109LSA Marine cam - you "got your vacuum signal back" with the RHODES lifters - which are NOT recommended with computer controlled engines - why ? they trigger the knock sensors which results in timing pull back. AND, like the louder roller tip magnum rocker these RHODES are even louder. So you have a van with a whole lot of machine noise under the cowl I bet. So we are not taking just an 109 LSA in the VORTEC, you have a 109 LSA crutched to work with the computer using the rhodes lifters. And no doubt the tune is was to make it work without codes - my point, the 203 203 is a drop in, makes more power and torque, longer torque with no codes nor tuning.

No rhoads lifters in that 350. My current 383 has a 218/228 @ 0.050 108 lsa and rhoads.

 

[Supercharged111]

the "tuning hell" was the cost of the computer upgrade because the pre-1998 computers are obsolete as far as the tuning world is concerned. Sure you can tune them, but the cost and scarcity starts making it of questionable economics. Look at the insano quotes for some mailorder tunes like blackbear -their cost justification centers around a computer that requires hard to find EFI Live dongles. Same with other tuners with the archiac Jet Performance tuning envioment. Agree we are talking wee cams here, but wee cams+ make a stock vehicle run like sh__ off the rack. Look at all the jim-crackery that L31Express had to do to make his 109 LSA work .. IE rhodes lifters. My point is 1) drop in cam drive and forget cam, 2) nice performance upgrade and 3) over .500 lift is a waste given the limitations of the vortec head SANS porting.

My 350 has a 109 LSA and fired up and ran like stock. A black box is no more difficult (98-00) or expensive to tune than a 411. Seriously man, you are way off base here. Plus knock sensors can be tuned and turned off.

 

[Hipster]

Agree we are talking wee cams here, but wee cams+ make a stock vehicle run like sh__ off the rack. Look at all the jim-crackery that L31Express had to do to make his 109 LSA work .. IE rhodes lifters. My point is 1) drop in cam drive and forget cam, 2) nice performance upgrade and 3) over .500 lift is a waste given the limitations of the vortec head SANS porting.

Almost all cam manufactures offer some type of fast bleed lifter these days. They're all over the place. Not as jim-crackery as one would think. Agree on Vortec head flow. Not a whole lot of sense of opening the valve to the point where airflow/velocity falls on it's face or goes turbulent. It's counterproductive to power output and makes for it's own tuning issues yet many guys will go for that big cam or go with 1.6's trying to get to a big lift number.

 

[Supercharged111]

Almost all cam manufactures offer some type of fast bleed lifter these days. They're all over the place. Not as jim-crackery as one would think. Agree on Vortec head flow. Not a whole lot of sense of opening the valve to the point where airflow/velocity falls on it's face or goes turbulent. It's counterproductive to power output and makes for it's own tuning issues yet many guys will go for that big cam or go with 1.6's trying to get to a big lift number.

It's not completely worthless to go past max flow, consider lift/flow under the curve.

 

[Frank Enstein]

Kodiak Marine SAE dyno chart.

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That torque curve is just plain sexy!

 

[Hipster]

That torque curve is just plain sexy!

Yes it is lol

 

[Frank Enstein]

I think there is some incomplete info on cams regarding lobe separation.

LSA is only one facet of cam design. It's possible to have a 104 LSA idle glass smooth and a 118 LSA shake the fenders off the truck. The key is overlap when both valves are open at the same time. The higher the overlap the rougher the idle although fast bleed lifters and the tune can mitigate this somewhat. For example, increased timing advance at idle can smooth the idle somewhat.

One affect of a tight (low number) LSA will be a torque curve that favors the middle of the curve but a wide LSA (higher number) will flatten the torque curve for more bottom end and top end at the expense of mid range torque.

All this is dependent on everything else in the engine! Compression ratio, head design, stroker or not, cubic inch, intake and exhaust manifold type, & etc.

Bottom line no one spec on a cam defines it. It is all the specs working in concert with the engine build and the tune that defines how the engine will operate.

And last, some of the people on this forum (or any for that matter) are new to the game and may have a more black and white view because they do not yet understand the complexity of how all this works together. Just know that this forum is a friendly place to learn, teach, & share in the love of our trucks.

 

[Frank Enstein]

And I also recommend a tune before anything else on anything 1996 and newer.

Not getting the computer tuned after making a change is like bolting on a new carburetor and not tuning it. It may run better but not to it's full potential.

 

[PlayingWithTBI]

And I also recommend a tune before anything else on anything 1996 and newer.

Hey! What's wrong with 87 - 95?