Computer controlled cam

[98k2500]

I'm not sure what "logic" they use, mabye they guesstimate whether or not a stock tune will run worth a crap? Stock ICL is 111 on the Vortecs, 109 for the marine cam which GM specs with its 383 that it specs with a stock tune. That second one that L31 linked says not computer compatible which is a load of crap. Hopefully this puts OP's mind at ease.

Yeah, I wanst sure what they meant by computer controlled so wasn't sure if I had to specifically look for a cam that would fit my application plus make sure it said "computer controlled"

 

[98k2500]

In this day and age my first consideration has to be in my emissions state, is it 50 state legal compatible. Then choose what fits my driving objectives. If the smog isnt a problem alot computers can adapt to perform well on cam change. The problem starts when radical profiles 4500 to 5500 rpm power grind. With crap idle, vaccum drives the ecm nuts. I have to look it up but i think the crate 383 comes with a different cam grind, not the hot one the replacement upgrade. Another thing the manufacturer s have deal with is not just the math, cam specs grind etc, shows it falls wthin approved parameters. Calif. Requires physical actual testing, on vehicle dyno soforth. Rather than spend that kind of big dollars that the state could still say " nope not ever". They just say " not compatible". It's a tough game for aftermarket suppliers.

Very interesting. I had no idea. Thanks for the info

 

[Erik the Awful]

Call your cam company!

Anything else is just opinion, speculation, or advertising. The cam company of your choosing can recommend their best cam for your application.

 

[L31MaxExpress]

In this day and age my first consideration has to be in my emissions state, is it 50 state legal compatible. Then choose what fits my driving objectives. If the smog isnt a problem alot computers can adapt to perform well on cam change. The problem starts when radical profiles 4500 to 5500 rpm power grind. With crap idle, vaccum drives the ecm nuts. I have to look it up but i think the crate 383 comes with a different cam grind, not the hot one the replacement upgrade. Another thing the manufacturer s have deal with is not just the math, cam specs grind etc, shows it falls wthin approved parameters. Calif. Requires physical actual testing, on vehicle dyno soforth. Rather than spend that kind of big dollars that the state could still say " nope not ever". They just say " not compatible". It's a tough game for aftermarket suppliers.

HT383E comes with the same cam that has been in the Marine engines since the early 90s. 196/206 @ 0.050, .431/.451 lift, 109 LSA and 106 ICl. Works well for torque under 4,500 rpm. No surprise since it was developed for stern drive boats that do not see the high side of 5,000 rpm. HT383 is the same engine as a Marine 6.3L. Mercuriser rated them 320 hp with the marine manifolds and all the accessories in place.

My cam is 218/228 @ 0.050, 108 LSA, 0.578 lift with the 1.7 rockers and degreed in on a 106 ICL. 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.

 

[GoToGuy]

Yes I remember reading about the Rhoads lifters, many years ago.

 

[RI Chevy guy]

If you have to deal with emission testing, look into comp cams 08-300-8, made for computer controlled oe roller cam blocks. Should give you the gains your looking for without having to re-tune the computer, which on out trucks can be an enormous paint in the ass

 

[L31MaxExpress]

If you have to deal with emission testing, look into comp cams 08-300-8, made for computer controlled oe roller cam blocks. Should give you the gains your looking for without having to re-tune the computer, which on out trucks can be an enormous paint in the ass

That might work on a stock tune, but in all reality there is more power to be had with tuning and the stock cam than there is from a cam swap and no tuning. L31 starts out pig rich in power enrichment, when it ever gets into it and the timing curve and total advance is limp wristed.

 

[REM777]

Ran some EAP Simulations on the Delta Camsafts ( Tacoma Washington ) 203 203 regrind - almost no advantage to going to bigger Comp or Howards cams - the 203 is a little down on torque from the stock L31 - but the 203 203 has a broader torque curve and makes more horsepower - I have it in a 1998 MPFI truck - has a slight lope but is smooth and no codes or MPFI anomalies - Im running 9.4 CR and 1.6 comp rockers with the AlexParts VORTEC spring kit (which was a drop in )

Valve Spring Kit, SB Chevy VORTEC, HI-Perf Hyd Roller, 130 Lbs Seat Pressure, VSK4H53

$129.50 ​ Valve Spring Kit, SB Chevy VORTEC, HI-Perf Hyd Roller, 130 Lbs Seat Pres...​ Valve Spring Kit, SB Chevy VORTEC, HI-Perf Hyd Roller, 130 Lbs seat, VSK4H53

Cant light up the tires - but runs great, doesnt run out of air or fall on its face in upper RPM range - 13 mpg so far .. which is what it got before .. is a drop in great value over stock and according to the simulations the bigger comp and howards cam didnt show an improvement worth the tuning grief and expense. The comp and howards cam are definitely bigger - and from the simulation they definitely make more power - but mailorder tuning the GMT400 computer isnt easy.There is little benefit to going to the LS computer for the 1998 trucks by the way.
If I had to do it over again, I would have run the 383 crank - but this truck REALLY runs good. One other issue, be careful when ordering MAHLE replacement pistons - they lower the compression height assuming that rebuilders will deck the block as a matter of course . I had to deck cylinder heads and use the shim gasket to maximize the compression ratio. The 203 cam from DELTA is a corvette lobe on both intake and exhaust on a slightly wider lobe center. I am running the 1.6 Comp magnum rollers - these are made from a slightly tougher chrome moly than the PDRs ..( Chinese copies). Finally , not sure the value of running the bigger howards and comp cams with the stock MPFI which is limited in flow - this is the biggest reason I didnt go bigger with the cam.



print out the dyno simulatons and lay them on top of each other

 

[L31MaxExpress]

Ran some EAP Simulations on the Delta Camsafts ( Tacoma Washington ) 203 203 regrind - almost no advantage to going to bigger Comp or Howards cams - the 203 is a little down on torque from the stock L31 - but the 203 203 has a broader torque curve and makes more horsepower - I have it in a 1998 MPFI truck - has a slight lope but is smooth and no codes or MPFI anomalies - Im running 9.4 CR and 1.6 comp rockers with the AlexParts VORTEC spring kit (which was a drop in )

Valve Spring Kit, SB Chevy VORTEC, HI-Perf Hyd Roller, 130 Lbs Seat Pressure, VSK4H53

$129.50 ​ Valve Spring Kit, SB Chevy VORTEC, HI-Perf Hyd Roller, 130 Lbs Seat Pres...​ Valve Spring Kit, SB Chevy VORTEC, HI-Perf Hyd Roller, 130 Lbs seat, VSK4H53

Cant light up the tires - but runs great, doesnt run out of air or fall on its face in upper RPM range - 13 mpg so far .. which is what it got before .. is a drop in great value over stock and according to the simulations the bigger comp and howards cam didnt show an improvement worth the tuning grief and expense. The comp and howards cam are definitely bigger - and from the simulation they definitely make more power - but mailorder tuning the GMT400 computer isnt easy.There is little benefit to going to the LS computer for the 1998 trucks by the way.

print out the dyno simulatons and lay them on top of each other

Not trying to nit pick, but your stock cam simulation is a bit off as far as cam timing goes. Stock cam is 191/194 @ 0.050, .414/.428 lift, 111 LSA and 106 ICL.

The 196/206, .431/.451 marine cam on a 109 LsA and 106 ICL makes over 300 hp and nearly 400 tq and makes 390 ft/lbs as low as 2,500 rpm.

 

[L31MaxExpress]

Kodiak Marine SAE dyno chart.

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