446ci with LS7 Heads
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The guy i talked to said they have a 253 and a 255 as well on the XER, but he said they would only run to 6500 rpms "or it'll destroy the valvetrain"...phhhffff...whatever...haha. The guy I talked to was a real jackass when I asked if there was anything larger, so much so, that I just hung up on him lol.
I think I'll stray away from the solid lobes, i don't want to "destroy the valvetrain".
I think I'll stray away from the solid lobes, i don't want to "destroy the valvetrain".
Originally Posted by crb99ws6
valve open = 19.4 BTDC
centerline = 109.5 ATDC
valve close = 58.1 ABDC
duration = 257.5 CRANK DEG
lobe lift = .38059 IN.
valve lift = .647 IN.
lobe area = 33.12 IN * DEG
EXHAUST
valve open = 70.8 BBDC
centerline = 117.5 BTDC
valve close = 16.4 ATDC
duration = 267.3 CRANK DEG
lobe lift = .36634 IN.
valve lift = .62278 IN.
lobe area = 33.31 IN * DEG
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Dave has a valid point, just dig up that flow graph that Katech posted. As far as your cam, you'll have to post dur's at .006/.05/.2 so I can compare/contrast lobe styles.
I'm looking at something at 242/255 now..."its going to rip"
I'm looking at something at 242/255 now..."its going to rip"
Originally Posted by SLED28
Too much lift for 1.8 rockers and stock LS7 heads.... They only flow up to 620 lift then die... ALthough with the intake on, its not as drastic at .620 lift and higher
Have a look here. I don't think reducing lift on the ls7 head will do anything but cost you power considering your valve train isn't going to see .620 lift or whatever gross lift because of deflection anyway.
"its like the old NHRA SuperStock Rules/ Cylinder Heads
back then, a typical unported Legal SBC Heads usually stopped
gaining Flow CFM on a FlowBench, at and above .450-.500" Lift,
yet,
everyone found much more HP using Solid Roller Cams
with .660 to .740" Lift" A quote from Larry Meaux on that subject.
I don't think the ls7 head does anything that drastic past .600 that would cause you NOT to lift the valve past .600.
http://www.compcams.com/Technical/Ca...obeCatalog.pdf
Have a look in the comp master. They can put just about any of the roller lobes on the ls1 core cause it's so damn big compared to everything else. Just cause it doesn't say "designed for ls1" doesn't mean it can't be used on an ls1
. For instance, the extreme marine roller hydraulic lobes go all the way up to 278 at .050 and being their designed for the heavy big block valve train and you want to use a 1.8 rocker they may work very well for you. Not 100% posative but I bet they can be put on the ls1 55mm core.
Lots of morons that work at comp, and some geniouses as well. You kind of have to get lucky if you're not an engine builder to get through to the right guy, ha.
How much deflection do you think it loses with Morel lifters?
I have many times put BBC lobes on LS1 cams, and other small blocks....And Haas and I looked at every lobe in the catalog the past 2 weeks trying to get this 101% right!
Dave
I have many times put BBC lobes on LS1 cams, and other small blocks....And Haas and I looked at every lobe in the catalog the past 2 weeks trying to get this 101% right!
Dave
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From: Fort Worth, TX
I remember you mentioning this before, and the fact that you're running some damn high lift despite the fact that your heads "stopped" flowing a while ago.
I have been thinking that the reason why people find so much more power with the higher lift is the amount of time spent at that particular lift point, because if you stop lift at say .62, when your heads reach "max" flow, then you only hit that lift point once....BUT, if you run your lift to say .67, you're going to hit that point of maximum flow twice, and for more degrees of dur then just touching it on the nose. Thats my theory behind it, but thats just based on what I THINK is happening, and not substantiated by fact....lol.
I have been thinking that the reason why people find so much more power with the higher lift is the amount of time spent at that particular lift point, because if you stop lift at say .62, when your heads reach "max" flow, then you only hit that lift point once....BUT, if you run your lift to say .67, you're going to hit that point of maximum flow twice, and for more degrees of dur then just touching it on the nose. Thats my theory behind it, but thats just based on what I THINK is happening, and not substantiated by fact....lol.
Also we are trying to keep the valvetrain light so the beehives we picked are good for just under 700 lift and with the 1.8rockers, there's not much to pick from... We do want other specs, but couldn't fit it into the overall setup...
Dave
Dave
Last edited by SLED28; Jun 28, 2006 at 07:01 PM.
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Verdad Gallardo Here's the rest of the cam info.
Intake Lobe
Duration @ .006" - 306
Duration @ .200" - 164
Exhaust Lobe
Duration @ .006" - 316
Duration @ .020" - 295
Duration @ .200" - 166
LSA: 113.5 CAM DEG
valve overlap: 35.8 CRANK DEG
Intake Lobe
Duration @ .006" - 306
Duration @ .200" - 164
Exhaust Lobe
Duration @ .006" - 316
Duration @ .020" - 295
Duration @ .200" - 166
LSA: 113.5 CAM DEG
valve overlap: 35.8 CRANK DEG
Thread Starter
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From: Fort Worth, TX
That would be a horrible choice for cam lobes. The intake lobe is WAY too big, and to top it off, the dur at .2 is pretty low for being a .657 lift lobe and a 257 dur at .050. Wtih the XER, you can have 165 at .200 at a 242 dur and have a MUCH lower .006 dur to BUMP WAY UP your DCR. These lobes look to be poor performers, they just seem to be pretty slow.
The lobe he chose is still close to the same ramp speed of an XE-R, but it must come on later. Were the XE-R may jump off the seat fast, his may jump from .2 to .4 faster than the XE-R. It's just one of those things about cam profiles. Maybe saying there slow off the seat may be a little better than just "slow", because it isn't. I agree that it's a bit big for a 402, but it may be helping a bit seeings how the ET 245's he has are intake crutched.
Haans, remember that your 1.8 rockers will make the lobe faster everywhere in comparison to something with 1.8 rockers. I would certainly think you'll have to pick a slower lobe for your valve train to work with any kind of higher rpms. My lobes are not meant for a huge ratio rocker that I have by any means, but because I run a solid cam I can throw lots more spring pressure (250/700ish) at the setup to control things. also, I have titanium valves and in the big picture 7500rpm isn't a whole lot.
As far as deflection probably not a whole lot. Hydraulics don't have as much according to what i've been reading and discussing with others. Maybe .010-.015 or so. That is also assuming the morel lifters don't give any thing away in translating the true shape of the lobe to the valve (that is they don't allow the pushrod to travel farther in the lifter then their correct function when oil body is locked out would dictate or pump up when traveling over the nose of the lobe).
As far as the lift thing I tend to agree and THINK the same thing. Many others that i'd consider "in the know" believe the same thing and it does make good sense. More duration at higher lift points being the point with higher lift cams generally.
As far as deflection probably not a whole lot. Hydraulics don't have as much according to what i've been reading and discussing with others. Maybe .010-.015 or so. That is also assuming the morel lifters don't give any thing away in translating the true shape of the lobe to the valve (that is they don't allow the pushrod to travel farther in the lifter then their correct function when oil body is locked out would dictate or pump up when traveling over the nose of the lobe).
As far as the lift thing I tend to agree and THINK the same thing. Many others that i'd consider "in the know" believe the same thing and it does make good sense. More duration at higher lift points being the point with higher lift cams generally.
Originally Posted by SLED28
SLO, but Andy's just make 600rwhp (440ci/GM LS7head) with a small cam and small lift not hitting those big lift's. Probably .625 lift.....
I just feel its easier on the valvetrain if you run .625 vs .675 lift, especially with a hydraulic setup... WHats the most lift you have run in a Hyd roller LS1 succesfully?
Originally Posted by SLED28
I just feel its easier on the valvetrain if you run .625 vs .675 lift, especially with a hydraulic setup... WHats the most lift you have run in a Hyd roller LS1?
Yeah, if you're going to keep everything hydraulic less lift will probably work better when considering the valve trains ability to control things. Good luck with that setup, look forward to hearing about it in the futuer!
Originally Posted by SLED28
Me Too! I think haas will go solid roller next year as its quite a bit more expensive... What companies have adj rockers for the LS7?