BBC 509cid tunnel ram efi build.
 

Need some help to choose a camshaft and compression ratio. Srp 17cc solid dome piston that can be milled to set the compression from 9.1 to 10.6. Euro 98 5% ethanol fuel, equalient to us 93. The piston to wall clearance is honed for a mild boost in mind for the future. Valves are ferrea 6000 so that may be a problem in boosted aplication, dont know? looking for around 600hp n/a power so, 3psi should make +700hp and 6psi +800hp. 26ft chris craft stinger 5300lbs dry weight, rised X-dimension, bravo drive. planning was not an issue with old 500hp 509cid engine. was thinking 10 to 1 for NA and 9 to 1 for mild boost, but cant deside wich cam to use, comp has the duration and the other cam has the lift.

-GM gen6 block 4.5" bore.
-Eagle 4" forged crank.
-6.385" eagle H-beams.
-SRP forged pistons.
-Cometic MLS head gaskets, 0.04" quench.
-Flotek 290cc, 112cc chamber, 2.3"/1.88" ferrea 6000 series.
-Gm dogbone lifters or howards max effort (gaterman) retrofitt lifters in hand.
-Two cam options in hand, comp 236/236 050" 112lsa or custom 3lobe 228/230 for intakes 236 éxhaust. cam cards in pictures.
-Weiand Hi-ram converted to 8 point efi with 2x4brl 1000cfm throttle bodies.
-Mrtech ecu, sequential or semi sequential fuel, logig level wasted spark ignition.
-Stainless marine exhaust, 6" taller/dry to transom risers.
https://cimg9.ibsrv.net/gimg/www.off...b0fb59b7fb.jpg
https://cimg0.ibsrv.net/gimg/www.off...abc5019230.jpg
https://cimg6.ibsrv.net/gimg/www.off...185b72950d.jpg

If you used bushed rods, you could leave the CR higher for NA, and if you ever go boosted you could do a quick tear down/inspection and machine them to a more friendly boosted CR.

Flotek 290s are a good head choice.

Eric Weingartner on YT has many vids on Floteks and Promaxx 290/317 BBC heads with direct 496 dyno mule comparisons. 317s at the same compression as the 290s performed really well..and even made more power in the mid range part of the time. All at WOT of course. He goes into detail why the 317 port may be more efficient for airspeed, as it has a more consistent port.

The Stainless Marine standard size with 3" ports and dry risers are sufficient for 700hp without resistance. @ 2.2CFM/hp.
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Higher LSA would help with reversion, and if you went Supercharged in the future.

Mike Jones cams may have some options for you, vs off the shelf. I think he also has some good lifter options.
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Mike has a cam question sheet to fill out. Very easy solution for a 2nd opinion and likely a more tailored cam solution.

If those were the only cam choices, I'd go with the Comp cams and run 1.8 rockers. at the least on the exhaust side. 0.340" lobes are going to be easy on the valve train. (I do actually run 1.8's on my exhaust side) I really wouldn't be putting the 3 lobe gimmick cam in. After looking at the part number, who would be supplying that cam??
Why are these the only 2 cam choices? Are they cams that you already have?

the one,,the only,,cslob,,could smell that garbage a mile away.

I allready have these two cams. That gimmick has run in 9.5 comp peanut port 509cid. 530hp 5400rpm, 620lbft 3600rpm, i have nothing bad to say about it! Somehow i like the low lift of the comp cam, that may be easy for the valvetrain. Wonder where the engine would peak whit this cam? I would quess near 6000rpm atleast with 1.8 rockers. I have 1.7 crane golds wich are 1.76 i real life.

Personally , I like my CR lower, closer to 8.0:1 for blower and seat pressure clower to 200# but if you`re not running to 6000rpm probably fine.
Fill your cylinders with fuel and air instead of metal.
I wanted to go 7.5:1 but the the head gasket would have to be pretty thick.

Damn it was hard to decide put the domes are now machined to 6cc, wich gives me 9.8 to 1 comp for N/A power. Now trying find the perfrect lobes, and imo howards has the most interesting cams with less duration split. Someone said that picking a cam more complex than picking a wife.
https://cimg8.ibsrv.net/gimg/www.off...9cdd111ff7.jpg

In my opinion and from trial and error, less than 8 degrees of split didn't work that well on N/A or blown BBC

Call Comp with the lobe #'s and separation you want, à la carte. Done...
https://cimg0.ibsrv.net/gimg/www.off...c2fdebfbe1.jpg

Sporl perfomance suggested his 240/245 @050, 646/646 lift, 114lsa. Does anybody have any experince with sporl cams?

Not a bad cam. I don't believe your exhaust ports flow enough for 5° split. I run 6° (237°/243°) but my heads have been extensively ported and flow 300+ @ 0.650"

+300 @650 for exhaust? wow! Floteks flows, int 340cfm @650", exh 270cfm @650". I/E ratio is almost 80%.

It looks like the 290s drop off after .600 lift, what is the point in going with a .650 lift cam.

Flow numbers at flotek site are advertised too high. Check Eric Weingrtner video @ yuotube if yuo are interested. peak flow at 0.700" lift, untouched.

Review for stock 290cc

Modified 290cc

Why would you use those on a 509

if you believe flotech's flow charts,they flow really well.

I don't, but what are you comparing them to ? they still seem small for a 509 that may get a supercharger. There again, that's only my opinion.

Here is comparison of the valve timing events of all the cams i have mentioned in this thread. Looking only the duration, the Sporl perfomance cam looks most agressive, but because the wider 114lsa its lil milder than the crane 741.

From left to right in the picture.
-Custom 230/236,112lsa
-Comp 236/236,112lsa
-Sporl 240/245, 114lsa
-Crane 741. 236/244, 112lsa
https://cimg1.ibsrv.net/gimg/www.off...5aab92b3a2.png

What id it about the cam, that you are you calling it ‘milder’ ? The 114 vs 112 lsa ? Did you miss the rest of the #’ when comparing ?

You are right, Milder might be wrong word, but it has slightly less overlap looking at only the 050" duration. Ron did not give me the advertised numbers of this cam.

OK, I bought sporl performance 240/245 cam. Ron said it would make 650-675hp in marine trim with 9.8 to 1 comp, 12" vacum @ 800rpm idle. 650-675hp seems high to me, i think he meant std corrected power, wich means approx 625-650hp j1349 corrected. I would be really pleased if i makes 625hp.

Because it is. The cam has the potential to make that much HP. Your build does not.
I believe you have a good mild build going on, not a 1.31 HP/cuin build.

Fwiw I know someone that used that ron sporl grind in a modded 502 mag, had a chopped down , extrude honed intake, bored tb, dart heads. He advised customer to advance it some, guy randomly advanced it i think 4 degrees without bothering to degree it, broke 620 hp on my dyno at about 5500/ 5600 using J607, dry dyno headers with mufflers and no accessories fwiw, Smitty

I've seen 630hp w/ a crane 240/248 ls112 for an 8.1L in a gen 6 502,cams a double swap,dart heads 10-1 compr. on an ego breaking dyno.:)

Ron advised me 106-108icl, hopefully my tunnel breaths Lil better than the modified merc intake. Stainless marine manifold would have robbed atleast 20hp from that 620hp.

The tunnel ram and exhaust will not be the limiting factor, the heads will be the limiting factor.

Cant wait to see the flow numbers after valve/seat job, and bowl/chamber blend.I think the 2.3" intake valve should be plenty, and the port itself is the restriction. Intake port CSA is around 3.0sq" untouched.

Got the cam card

https://cimg6.ibsrv.net/gimg/www.off...e0cd4de6b8.jpg

will be interesting to see how that 5° split does for power.

Dont you think the merc intake was a restriction? 5600rpm sounds low for 240/245 duration cam, makes me wonder if it was the Rons milder 230/235 114lsa. Still have the dyno sheet?

Yes, the runner length of 14/15" dictates hp peak on these restricted intake engines, even with intake mods, You can add more and more cam on them and gain nothing, just shifts tq peak to a higher rpm with less overall torque. Modding the runner length and cutting dividers gets them to carry about 200 rpms higher. With your tunnel ram Id expect that cam to easily pull to 6000. IF your dynoing it, would be interesting for you to install a adjustable timing chain and cover that allows you to easily access it and move cam timing around on the dyno and see where your tq vs hp peak goes then make a decision of which ones more important to you.
FWIW, the guy with the modded 509 w that cam ran 84 in a 280 PQ at LOTO shoot out on day one and 85 on day two (after tearing all the interior out of cockpit and putting it in back of his truck on saturday night)! think that was 3 years ago. We saw 78/79 on local river when checking/touching up the tune before he tried multiple props.

Testing the cam timing at dyno has been in my mind, just trying to find cost effective 2pc timing cover, those Fancy comp cams covers costs the same than my custom billet cam. I ones had a cheap speemaster 2pc cover, and the fitment was not that bad, i quess they dont make it anymore.

That pq280 seems to be fast hull, is it true 28ft hull?

There a stepped hull, Ive heard that steve Stepp or something to do with Velocity had input on that 280 PQ hull. I bought a stock one a couple years ago w stock 502 as a quick flip/plus used it to fully develop a 60 lbs injector tune for mefi3 on 100% stock boat, it ran 67/68 gps after bottom was cleaned and was running perfect. Most those 26/27/28 ft boats will barely break 60 gps w stock 502 mags.
Another customer had one and another 509 I dynoed and tuned with promax heads made around 610 on a glory pull and around 580 with marine exhaust and water in exhaust, that boat ran 81/82 at shoout a year or 2 before the other one I mentioned

Jani,

I have an '02. I think it runs really well for the power you give it. Mine has the 496HO with the Whipple stage 2 tune and an M1 ProCharger. Procharger advertises this kit at 615HP. Opinions vary as to what it actually puts out; some suggesting as low as 500. I turn a Bravo1 28P prop, and we run 76-77GPS, maybe 78 on a perfect day, and it will still pull my fat ass out on a slalom. It climbs on plane with little more than 3K RPM, cruises at 30-35MPH at about that same RPM. I think there's more in it (mine) with a more efficient (labbed) prop, but I don't think I can pull a 30P with a happy engine. I've seen videos of them running 85 or so, but I have no idea what power was in it. They run clean and stable at that speed. I think the hull is actually spec'd at 27'6", including swim platform.

Thanks. Brad.

Sounds good! I am trying to get my old 26ft stinger above 70mph. Really like the ride of the old stinger, the only problem is porpoising at wot. Mine is with raised 17.5 x-dimension, and also jumps to plane. Those stepped hulls are in different level for sure.

Confirmed the dome volume from JE tech support, for the 0.079" dome height what is left after machine work. JE confirmed that it is approx 7.48cc instead of 6cc that was my own calculation. This gets me 10 to 1 compression. I repeat approximately 7.48cc 🤣🤣🤣. I got the answear in 1 hour, gotta love Je tech support 👌

The one video thats out there of racin jason at loto running 85 on sunday at shootout i think 3 years was the MPI 509 engine I dynoed and tuned that made 620/620 here. The announcer calls it a velocity in the video because he had a velocity the year before or something.

You can always put it down .100 in hole and seal it then cc the difference too if in doubt