Cam Suggestions for a 540
 

I have been looking to replace the HP500EFI in my Cougar. Well I fell into a very good start for a 540. Dart big M, CNC AFR335s, 4340 Scat crank and H beam rods. Plan on using Mahle flat tops for about 9.3 cr. and EZ EFI2.0. Premium fuel is not available so it has to run on 87 octane as well.

I am looking for a bulletproof 600-650hp. so it doesn't shred the drive. I have been thinking about using a crane 168741 with 114 degree centres rather than the 112.

Comments and suggestions please.

22MTR

You could go with 6-8 degrees more duration or so and a Dart Tunnel Ram(lol).....shift your power up the rpm range a little.
Your boat won't need mountain moving torque and your drive obviously won't like it anyway.

Sounds like a good foundation you have. Those cubes and those heads want to be fed - so feed them.

wanna see this thread... subscribed.....

I'd call a couple cam guys / grinders and see what they come up with.

Marine kinetics, cam motion, crower etc. and let them know what you're doing and how you plan on using the boat. (Be as accurate as you can. GI = GO )

Before we ordered my cam we talked to the three I referenced above and they all specified cams that were remarkably close.

http://www.offshoreonly.com/forums/g...o-results.html

Ultimately after some tuning , ^^^ this combo made around 680HP if I recall with only 9:1 static, and pushed a 35 mistress to upper 70s, with the 741 Crane cam. Those valvetrains lasted quite some time as well. This was 12 years ago.

That's interesting to see the link above. I built pretty much the identical engine except with 305 heads(thought incorrectly that I had 315 heads) and peaked with 660 @ 5700 and I don't believe it left the dyno quite as dialed in as it could have been.

My builds pushed my Mistress to 73, looks like some dyno time for me this winter to see WTF I am missing, going off dyno sheets of my old engines these don't have the TQ I need....

if my engines were in a lighter boat I bet the results would be better...

I should start the most TQ 540 thread lol

Thanks for the thread. Looking at it, it is 315 heads. Wondering how much the 335s will move things up the rpm band. Also what is max input RPM for a bravo XR??

This is the dyno sheet from the link mild posted. The photo is mine. I don't have my cam specs on hand, but it's a mild hyd roller. Other than that you're seeing the difference between the 305 and 315 heads.
*edit- well for some reason I can't copy and paste the chart from the link. Oh well

Do you want a cam that simply makes a good number on the dyno pull, or a cam that opens and closes the valves gently, can be run with less spring pressure, less lift with longer spring life, and maybe sacrifice a few HP to do so?

Theres more to a good cam choice than the dyno number the engine makes, or where it makes its peak power.

I read two important words...

Bulletproof and 87 octane ;-)

MT, Excellent questions!!

My first priority is reliability. I am not interested in the big number per say rather a strong reliable 600-650 hp on 87 octane. The springs that are in the heads now are the stock AFR springs,coil bind I believe is over.800 so that is not a worry.

I am after an engine that makes useable power from 2-6000rpm, shifts well and does not have an appetite for parts !!

Which spring # is in the heads ? Or stripe color, i wanna say the hyd roller spring that comes with afr heads is a "pioneer" spring.

Dont get too far away from your max lift to coil bind distance. Too far is no good, too close is no good.

If youre going for longevity, hard to beat a true endurance spring from isky/psi or Pac

I have these made the chris cat go 121 mph Dart tunnel rams rule!!!! Have a pair I'll sell

Just got off the phone with AFR. The installed springs are the older 8031 spring max lift .750 for solid roller... Guess they will be going up for sale soon !!! Might also have a set of stainless exhaust valves, for sale, very soon too ..

Nice !

WetteVette's 22ft WPM went near 130 with a Dart Tunnel ram too.

Nice but I plan on running EFI.

Recently saw him at the SBI races. Asked him if he misses the go fast stuff. He said not really, mostly because , he felt there was nothing really new going on that technology wise that was much different than 10 years ago. Craig is a sharp guy.

If i was to get away from superchargers, and went back to NA, tunnel ram setups would be the route i would go.

Do some efi tunnel ram setups :)

I hit like because that would be great, but the OP and you and some others are going in a different direction with camshafts.

If the engine was to be designed around say a 6200rpm or so WOT rpm range, then the Dart Tunnel ram would be pretty much close to odeal. If he is going to stay with say 5400rpm and down (as it sounds now) then wouldn't really be worth the little extra effort and $$$$.

Why 5400 and down for max rpm? Im not against adding duration, I just don't like big lift with short duration, and nearly solid roller ramps on a pleasure hydraulic camshaft.

SB

I am thinking about a 6000 rpm redline. Given the parts that I have I don't think that is excessive, likely get away with another 1000 with no issues other than the need for a stud girdle, but that is a standard BBC issue when you start to rev them.

I am not adverse to running a tunnel ram but I am becoming concerned about total port volume/cross section area and the resulting decrease in flow velocity.

I have found a few threads dating as far back as 2003 using the 335s on 540s and they seem to make more power than I am looking for... This is with high rise rather than tunnel ram intakes. I realize that I can make a ton of very reliable power with this combination, but I am putting it through a bravo XR, so in the interest of not building myself a drive breaking monster I want to keep the power in the 600-650 range with out completely neutering it... I know that Mild Thunder has been involved in a couple of similar builds so I look forward to the input.

I have seen a couple of setups with the EZ-EFI 2.0 and that has impressed me with its self-tuning capabilities. The application was BBC again but in cross country race trucks.

Keep the ideas coming !! I appreciate the input!!

What exhaust system you going to be running MTR?

A properly tuned tunnel ram will increase air speed not slow it down.

That's where it sounded like you guys where going.

By the OP's last post, I guess not.

Well, that said.....would a 242/248 with .650" or so be out of touch " ?

I think we are close SB. Something like this would work nicely

http://crane.carshopinc.com/product_.../140173/139681

The 741 crane works good too. I had a flat top piston 540ci with 741 crane , stock crappy merlin iron heads , made right at 600hp at 5800 with a dart single plane.

Here's a look at comp's master lobe profiles they grind from. Page 16 is their marine grinds. They aren't offering anything in .650 lift with a 1.7 rocker, until the duration gets up to 254 range. In the 240* range, their "High lift" profile, is a .360 lobe/.612 valve lift. Seems like them and crane, are generally on the same page with lobe sizes for basic bbc marine/endurance stuff. Maybe the independent cam guys know some things they don't about duration vs lobe size, spring life, and so on. Possibly having in house spintrons, and grinding machines, might be a benefit to designing cams for all different applications, I would assume.

http://www.compcams.com/Technical/Ca...obeCatalog.pdf

CMIs from the HP500EFI

Comp and Crane stuff are older lobes.Up until recently we didn't have hydraulic lifters that would support the higher lift cams. Now we do. About a year and a half ago I called everyone and there brother trying to find .700 + lift hydraulic lobe profiles. The only ones that had them were Bullet and Cam Motion. I highly doubt the larger companies are going to get into more exotic hydraulic cams for BBC I really don't think there is a big market for it. From what I've been told the LS market is really starting to pick up. And when you only need 1 cam core on the shelf to make whatever cam you want (instead of a gazillion) it's a no brainer (business wise) what to focus on.

if you don't have Inconel the "might be for sale valves" BETTER be for sale or your gonna have some issues soon....

Comp does have one .420 lobe hydraulic.

I think you dont see big lobe hydraulics much even today, because most guys wanting big lift, dont want a hydraulic, based on experience that they really dont hold up well in an endurance application, even with modern lifters. Kind of like why nobody is making 4 5/8 nodular cranks.

Whos running +700 lift hydraulic roller cams successfully in the marine offshore stuff, even with modern lifters ? Not talking about a dyno pull, or race engine, talking poker run or pleasure engines ? I hoestly dont know. I know of a few who tried it, even with the high end morels , and ended up going back to solids , in bigger power applications.

I have a serious question how much difference does 25CI actually make? like 540 vs 565?

Did you see page #13 ?

So.....if you call one of 2 'higher up' people in Comp Cams, you will more likely get another recomendation than the rest of the phone help and what is recomended in the catalog.

If you have the cyl head and induction system for it.... alot.

How do you feel about the difference of a 540 vs a 572 ?

They are for sale but they are not out of the heads so I am not pushing to sell them. Yes I am replacing them with inconel valves but waiting to see what happens with the USD CAD exchange rate.

not sure that's why I ask, the performance of my old engines and new ones are very different, I have less cubes with better heads and cams (I was told) vs a little more cubes and lots smaller cams and pro comp heads, boat still never beat last engines speeds... I mean my old cams only had .578 lift.....on 565CI

Just asking how many people had a quality stainless exhaust valve fail? He does only have a 22' boat. I had severe duty stainless valves in my twin turbo small block with no issues at 1800-1900 exhaust temp. Around 1000hp.

I have ..... twice.....only have a pic of one saved... here is second time after I didn't learn from first failure...

[ATTACH=CONFIG]546312[/ATTACH]

What brand valves? That thing is fubar

Pay a little now or a lot later.