LS4 / F40 swap - fieroguru (Page 3/203)
fieroguru DEC 14, 06:48 PM

quote
Originally posted by Will:


Wow... I would NOT have bought a cam from an outfit that wouldn't give me at LEAST *BASIC* info on the duration, lift and lobe sep. The fact that they do that and expect people to buy it black box is INSANE. If any outfit told me that, I'd tell them their competitor is getting my money. Holy cow. The fact that people buy it black box and just install it (without degreeing it as you've done) is even more insane. Do all the cylinders degree the same? In your shoes I would be *highly* suspect of any quality issue with that cam, from consistency of grind from lobe to lobe to material to heat treatment/surface hardness to straightness. I wonder if the outfit even knows what specs they're selling. Are your prepared to lunch your engine if that cam wipes a lobe into your oil pan? I know it's a roller, but crappy material is still crappy material.
I hope for your sake it's actually made of steel and not some tin plated lead casting out of China. Is it at least magnetic?




I had numerous conversations with this vendor prior to purchase and was able to get them to share that the intake was in the mid 220's and the exhaust was low 230's. Their argument was that they spent quite a bit of dyno time and R&D development for a DoD compatible camshafts and didn't want to advertise the specs for others to copy... While I did not like it, I also can't argue with their view point either. If they hadn't been the only DoD camshaft supplier at the time, I probably would have gone with a cam I knew the specs on.

The actual cam was manufactured by Comp Cams using their AFM cam core, so I have little concern from a manufacturing standpoint.


Will DEC 15, 08:44 AM

quote
Originally posted by fieroguru:
Their argument was that they spent quite a bit of dyno time and R&D development for a DoD compatible camshafts and didn't want to advertise the specs for others to copy...



While that may be true, I don't consider it a valid argument. There's *SOOO* much more to lobe design than the traditional "five number" specs. The guys in the Advanced Engine Tech section of Speedtalk frequently argue over velocity profiles, acceleration profiles, fitting polynomials to a lift curve while smoothing the 6th derivative... There's absolutely no harm in releasing the "five number" specs (and it just might get them more business) unless that's all they know about the lobes, in which case I'd still be worried.

What makes a cam "DOD Compatible" anyway?
KissMySSFiero DEC 15, 09:42 AM
I love the ign. Coil setup.
I'll be following this one for sure.

------------------
SSFiero@Aol.com 87 Gt-5spd-62k miles.

InTheLead DEC 15, 10:57 AM
Nice I like all the custom fab work~
dobey DEC 15, 11:00 AM

quote
Originally posted by Will:
What makes a cam "DOD Compatible" anyway?



The DoD profile has a lower lift limit due to the special lifters. There are also some other practical limits for the LSA and duration. Too much and there's a possibility of stalling out on the highway when the DoD kicks in, given the fact that you just lost half the cylinders.
fieroguru DEC 15, 11:10 AM

quote
Originally posted by Will:

What makes a cam "DOD Compatible" anyway?



There are 3 key camshaft requirements for the DoD lifters:
In 4cly mode the DoD lifters must be able to fully collapse internally to allow the valve to remain shut as the lifter rides the cam.
The opening and closing rate must not be to agressive.
The sping pressure can not go beyond a certain point.

The last two are interrelated and have to do with the locking pin in the lifters for V8 mode. If these factors are not taken into consideration, you will fail the DoD lifters in under 5K miles. After reading countless threads of people "trying" other factory cams (even the stock LS6 cam) and ruining the DoD lifters, I figued it was best to go with a proven design (from a DoD perspective) vs. taking a gamble with an unproven design. This particular cam has been on the market for 2 years now with around 100 installs and so far none have had any lifter issues.
So while the cam isn't perfect from a spec standpoint, I shouldn't have to worry about killing the DoD lifters.

Most camshaft suppliers choose not to spend the time R&Ding the cams for the limited DoD market and instead have chosen to offer DoD delete kits to replace everthing needed so you can run one of their many off the shelf cams.
Will DEC 15, 10:34 PM

quote
Originally posted by fieroguru:

There are 3 key camshaft requirements for the DoD lifters:
In 4cly mode the DoD lifters must be able to fully collapse internally to allow the valve to remain shut as the lifter rides the cam.
The opening and closing rate must not be to agressive.
The sping pressure can not go beyond a certain point.

The last two are interrelated and have to do with the locking pin in the lifters for V8 mode. If these factors are not taken into consideration, you will fail the DoD lifters in under 5K miles. After reading countless threads of people "trying" other factory cams (even the stock LS6 cam) and ruining the DoD lifters, I figued it was best to go with a proven design (from a DoD perspective) vs. taking a gamble with an unproven design. This particular cam has been on the market for 2 years now with around 100 installs and so far none have had any lifter issues.
So while the cam isn't perfect from a spec standpoint, I shouldn't have to worry about killing the DoD lifters.

Most camshaft suppliers choose not to spend the time R&Ding the cams for the limited DoD market and instead have chosen to offer DoD delete kits to replace everthing needed so you can run one of their many off the shelf cams.



Ok, so the lobe lift has to be less than the travel of the "disconnected" lifters.
What "fails" in the DOD lifters? Does the pin actually shear?
So it has to be a gentle ramp, "lift rule" lobe... interesting. You said one of your sources told you it was a "big" cam? Sounds to me like the gentle ramp rate means that the seat-to-seat numbers are much bigger than the .050 numbers, so it has much more overlap than a "normal" LSx performance cam with the same .050 duration.
fieroguru DEC 16, 11:10 AM

quote
Originally posted by Will:


Ok, so the lobe lift has to be less than the travel of the "disconnected" lifters.
What "fails" in the DOD lifters? Does the pin actually shear?
So it has to be a gentle ramp, "lift rule" lobe... interesting. You said one of your sources told you it was a "big" cam? Sounds to me like the gentle ramp rate means that the seat-to-seat numbers are much bigger than the .050 numbers, so it has much more overlap than a "normal" LSx performance cam with the same .050 duration.



I haven't seen any disassembled views of a failed DoD lifter, but when they fail they make a hell of a racket.
From what I have read the seat to seat overlap isn't much of an issue (not open enough to allow much air flow)... the stock LS4 cam has 87 degrees of overlap at .006, and -33 degrees at .050. My cam has 58 degees of overlap at .006, but does have 3.5 degrees of overlap at .050... it probably will have a some what choppy idle.

If you look at the diagram of the lobe graphs posted above, you can see the aftermarket cam has a similar opening curve for the first several lift points, then it speeds up slightly, lifts higher, stays open longer, then closes very similar to stock. The real difference is duration at .200 lift. The stock cam spends 106 degrees with the intake lift greater than .200, my cam has 144. A 224 came with more agressive lobes probably has a duration at .200 greater than 150 because it gets to that point in fewer degress on the ramp up.

This cam on the 6.0L engines installed dot to dot works in 4cyl mode (they say they picked this cam due to it performing best in 4cyl mode vs. the others they tried). The other LS4 guy running this cam installed it dot to dot. He has commented on his car peaking power just under 7K rpm and of a significant loss of lowend torque (still able to spin the tires, just 0-60 is slower). Based on that and the cam originally be designed around a 6.0L with more cubes/lowend torque, I installed my cam advanced of dot to dot to bring back a little on the lowend (picked up some dynamic compression ratio as well) and lower the peak RPM down some.

[This message has been edited by fieroguru (edited 12-16-2010).]

Isolde DEC 16, 01:50 PM
Good thing KY doesn't do tailpipe sniffer.
Also, I'd wager that cam was spec'ed for a 6.2, or at least a 6.0, back when they were first playing with it. At least your 5.3 can be bored to 5.7, that'll help some.
I'm fairly sure you're not gonna be trying any such thing anytime soon, but it is an option. And about as cheap as buying yet another cam, plus the then-necessary tune, which the extra cubes wouldn't necessarily mandate. Maybe if it maxed out your injectors, but otherwise... Anyway, just new gaskets, a few of which another cam swap would require anyway, plus a few bolts, bore / hone, a set of good used LS6 pistons with rings, and re-balance the crank. LSx bearings are re-useable unless damaged.

[This message has been edited by Isolde (edited 12-16-2010).]

fieroguru DEC 16, 02:05 PM

quote
Originally posted by Isolde:

Good thing KY doesn't do tailpipe sniffer.
Also, I'd wager that cam was spec'ed for a 6.2, or at least a 6.0, back when they were first playing with it. At least your 5.3 can be bored to 5.7, that'll help some.
I'm fairly sure you're not gonna be trying any such thing anytime soon, but it is an option. And about as cheap as buying yet another cam. Just new gaskets, a few of which another cam swap would require anyway, plus bore / hone, a set of good used LS6 pistons with rings, and re-balance the crank. LSx bearings are re-useable unless damaged.




Especially since the car will not have catalytic converters!
The cam was designed aroung the G8 6.0 DoD application.

I do not know if you noticed it while you had your LS4 apart but the LS4 block is actually longer than the other RWD Ls(x)'s. The FWD pattern is actually raised from the RWD pattern. This difference and the 3mm shorter crank is what makes the LS4's crank flange flush with the FWD pattern. So, in the event I want more cubes, I will probably just get a gen IV 6.0 or 6.2 long block, cut the 10mm off the snout, make a thin adapter to put the crank flange flush to the adapter plate, and swap over the rest of the parts (including all the DoD hardware). This would move the engine 3mm to the passenger side, but as long as I design the lower mount brackets for it... the rest of it will be plug and play.