Xfi 292 questions
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From: Southern Michigan
Xfi 292 questions Hey guys, here's the run down on what I've got. I am just assembling everything and motor set up is:
forged and ballanced 3.75" crank, forged 5.7" rods, forged 4.03" flat tops with 5cc reliefs (rings gapped for 250 shot), splayed 4 bolt caps and 'zero' decked block. Heads are stock aluminum castings, hand ported with 56cc chambers, new seats installed with Manley 2.02/1.600 race master valves, comp 918 beehives, stock ported intake, 42# injectors, 58mm Tbody.
Built 4l60e with precision 4k stall, 3.73 gears, 28" tires. Race weight is aproximatley 3200
I called comp for cam advice and they spec'd me a XFI 292 and the 918 beehive springs, which I purchased. After reading a little more into it, I feel the springs are a little on the weak side, and also since I don't have a huge set of heads, this cam may be a little on the big side. I am considering putting this set up together with 7/16 stud, 1.5 ratio rockers rather than 1.6's. I figured it will be a little easier on the springs and maybe not want to rev out so far as i'd like to shift around 67-6800. What do you guys think about going with the 1.5 arms rather than the 1.6's?
forged and ballanced 3.75" crank, forged 5.7" rods, forged 4.03" flat tops with 5cc reliefs (rings gapped for 250 shot), splayed 4 bolt caps and 'zero' decked block. Heads are stock aluminum castings, hand ported with 56cc chambers, new seats installed with Manley 2.02/1.600 race master valves, comp 918 beehives, stock ported intake, 42# injectors, 58mm Tbody.
Built 4l60e with precision 4k stall, 3.73 gears, 28" tires. Race weight is aproximatley 3200
I called comp for cam advice and they spec'd me a XFI 292 and the 918 beehive springs, which I purchased. After reading a little more into it, I feel the springs are a little on the weak side, and also since I don't have a huge set of heads, this cam may be a little on the big side. I am considering putting this set up together with 7/16 stud, 1.5 ratio rockers rather than 1.6's. I figured it will be a little easier on the springs and maybe not want to rev out so far as i'd like to shift around 67-6800. What do you guys think about going with the 1.5 arms rather than the 1.6's?
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Can you return the cam & springs?
The XFI grinds for their published lift specs are with 1:6 RR so going to 1:5 will lower the published lift specs some. The 292 is a big cam so the 1:5 RR idea may help tame it some
I run a smaller XFI cam and 918's are spec spring......but mine broke at 20k mi so you would need to be diligent in checking the springs and frankly don't expect to get 20k mi on them (read I would not use them)
I now run the Lunati springs Lloyd Elliott recommended. Bought them from him.
Valve springs are a wear item on aftermarket , especially aggressive, cams. I would go with the Lunati spring over the 918 bee hive. The Lunati springs will last longer and are dual springs so much better chance of not dropping a valve if one breaks vs the single spring 918.....which do have quite a fail reputation
The XFI grinds for their published lift specs are with 1:6 RR so going to 1:5 will lower the published lift specs some. The 292 is a big cam so the 1:5 RR idea may help tame it some
I run a smaller XFI cam and 918's are spec spring......but mine broke at 20k mi so you would need to be diligent in checking the springs and frankly don't expect to get 20k mi on them (read I would not use them)
I now run the Lunati springs Lloyd Elliott recommended. Bought them from him.
Valve springs are a wear item on aftermarket , especially aggressive, cams. I would go with the Lunati spring over the 918 bee hive. The Lunati springs will last longer and are dual springs so much better chance of not dropping a valve if one breaks vs the single spring 918.....which do have quite a fail reputation
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I ran the XFI 292 cam on a stock shortblock with a mildly ported set of Trickflow heads. I also ran 918 beehives and 1.6 rockers. I would run a different spring though. I did break a spring early on (replaced for free) and the engine currently has a broken one now (ran fine though). The cam will work with the heads you have assuming they move a decent amount of air. My Trickflows were nothing special, maybe moving 250-255cfm? I also ran a single plane intake, and more converter.
If it were me I would sell the cam and springs you have and start fresh. Based upon what I've heard I don't feel the Comp Cams tech line is a place I would ever want to obtain advice from which is a bit unfortunate. I'd feel a lot more comfortable getting a cam spec'd from a place like AI or LE or the like and they could also set you up with an appropriate spring kit. This is just my opinion of course and you can do whatever you feel is best.
At a minimum, I would definitely get yourself some dual springs. I have been running PAC 1518's single beehives on my XFI cam for many years but if I knew then what I know now I would have gotten duals from the get-go. The 1518's are a better spring than the 918's so my luck may not transfer to you and honestly I've probably only put 10k miles on them in the past decade so I'm still not out of the woods yet. Once my springs need replacing or perhaps even sooner for good measure I will be replacing them with some Lunati duals FWIW.
At a minimum, I would definitely get yourself some dual springs. I have been running PAC 1518's single beehives on my XFI cam for many years but if I knew then what I know now I would have gotten duals from the get-go. The 1518's are a better spring than the 918's so my luck may not transfer to you and honestly I've probably only put 10k miles on them in the past decade so I'm still not out of the woods yet. Once my springs need replacing or perhaps even sooner for good measure I will be replacing them with some Lunati duals FWIW.
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My $.02 at the very least sell the 918's. Take a $25 hit and sell them NIB on ebay
Those XFI lobes are aggressive and they will beat the shiat out of those 918's by 10k mi (especially at 6800 rpm shifts)....if they don't break first. You have the big boy XFI 468 cam. I just have the small 466 and killed mine between 15k-20k mi. This was checking a few at random every 5k mi prior. Admit-tingly I drive the car hard and run it at the track but never shifted past 6400 as the 466 was done 500 rpm before that.
I got lucky when mine broke. No engine damage. I was pulling them to put in my Lunati duals as the motor was nosing over at upper RPM's so my 918's were done. Pulled all the springs and when I went to remove the retainer from one of them...it was a 2 piece spring. I am assuming the break happened sometime between 15k-20k mi....but it could have been 1 mile after install as I did not pull every spring to pressure check at 5, 10 & 15 k mi, just a few random ones so this spring could have broken anytime.
That 292 is not a bad cam and you have all the other supporting mods (stall, gears, injectors, TB, etc) and will run a 200 shot. From a clean sheet of paper yeah I would likely go with a custom grind from LE. Your call if you want to take a small $ hit and sell the cam & springs and re-group on the cam spring thing......but at least don't run the 918's IMHO.
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I thought the cam was fine. About as high as you'd want to go running 350-355 cubes and the factory pcm. My converter was loose and stalled around 5000. Having a single plane intake setup helped a lot. Bast ET was 11.11 at 121.65 at a raceweight of about 3150lbs.
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Ok guys, well its too late to send the cam back and I think I am going to stick with it and see what it does. And even tho the springs and retainers have never been ran, they are already shimmed and set up on the heads, so I cant sell them as new. The car will only see about 1k miles a year at most, but alot of wot runs. I guess I am Definitely going with the 1.5 rockers arms at this point and see how it goes. It really suck comp spec'd me this set up, and at this point, it's clearly way too much with the advertised 1.6 rocker arms...
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well you ask the ? and everyone who replied that has a XFI cam and ran 918's had them break and the other chose not to use them at all but advised he wished he had gone with a dual spring.
For maybe $100-$150 more out of your pocket and some of your time you could sell the not used 918's and buy a better spring. The consequences of spring failure can be significant in engine damage.
It's really the aggressive ramps of the XFI vs the lift with the 1:6 that is hard on the springs....and the 918 is VERY prone to failure. Lloyd Elliott will not even sell or install them on his heads anymore
For your sake I hope you prove us all wrong
For maybe $100-$150 more out of your pocket and some of your time you could sell the not used 918's and buy a better spring. The consequences of spring failure can be significant in engine damage.
It's really the aggressive ramps of the XFI vs the lift with the 1:6 that is hard on the springs....and the 918 is VERY prone to failure. Lloyd Elliott will not even sell or install them on his heads anymore
For your sake I hope you prove us all wrong
I called comp for cam advice and they spec'd me a XFI 292 and the 918 beehive springs, which I purchased. After reading a little more into it, I feel the springs are a little on the weak side, and also since I don't have a huge set of heads, this cam may be a little on the big side.
It's a 383. I think it will be fine with the extra cubes, just plan on using the entire rev range of the factory computer. Get better springs and sell the 918s.
Also, check your PTV.
Also, check your PTV.
Yikes. Did not even see that. In that case, let it eat! I'm running that cam with COMP 26056-16 springs. My only gripe is the motor is a little more crabby at lower RPM than it was with my SR cam. Little sacrifices...
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Ok, so after the reputation I see from the 918's, I will be swapping them out, but sticking with the 468 xfi cam. I am thinking of going with the BTR platinum springs and retainers. What are your thoughts on those?
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FWIW when I was looking for springs to replace my 918's and asked as you did on forums the BTR came up. I decided someone like Lloyd Elliott was way more qualified than me....and others on the forums so I contacted him. His recommendation was the Lunati kit I note in post #2
Not saying the BTR's are not good...just followed the advice I and most regard as extremely qualified
Not saying the BTR's are not good...just followed the advice I and most regard as extremely qualified
The BTRs have an excellent reputation on this forum and Tooley knows his stuff. The springs are designed for use with LS motors so I am not sure if they are a direct swap for use with gen II LT1 heads. I would look into that one. The Lunatis have a specific kit for gen II LT1s and I saw them for under $220 on coloradospeed's website so that's a solid option. I'm putting a cam in my Vette and the cam designer recommends the use of a dual spring and specifically mentioned the Lunatis as a recommended spring so I pulled the trigger on the Lunatis last week over the BTRs for that reason but I would personally feel comfortable with either.
Beehives are a nice low weight option that the use of an asymmetrical shape that gives it harmonic dampening. Problem with them is that they have a checkered history and in the event of a breakage is less likely to catch a valve from falling than a dual coil spring.
From my experience I would not ask comp for advise, I went to a car show one time and at a comp cams booth I asked if I should use 1.5 or 1.6 rockers on a setup I had on my truck, I went three times to ask the three out of four reps and these were the answers I got.
I would use 1.6
I would use the 1.5
It really didnt matter on the mild cam I had, so it was basically up to me..
I would use 1.6
I would use the 1.5
It really didnt matter on the mild cam I had, so it was basically up to me..