What to expect out of a 496 CI
 

Just wondering what respectable but yet conservative number you can get out of a 496. I have been contiplating on stroking my 454's. I have always been able to achieve pretty good numbers and reliability from 454 rebuilds in the past however I was thinking of taking them to the next level. Reaching near 530 ft pds of trq and 500 HP at 5500rpm with 454/468's.
What would you think to expect with a 496 without going crazy. I'm ready to hang my rods and pistons to complete the short block and then I had a brain fart.

Any help with the project would be great so I can get moving here.

thanks,
John

:with everything else same as before,i think gains of 50 hp and 70 tq sounds right.this is a good question for dean,ray or tyler,ihope they post a reply on this.:evilb:

500hp max


After that call your padre.

Hmmmmmm. Really

It all depends. What exhaust, heads, cam, intake. The only thing I would do different when I built mine was different heads. I used Edelbrock 290cc. Other than that I spared no expense best of everything. Like said above, just adding 42 cubic inches I would be surprised to see 50hp.

It reminds me of my first V8 boating engine I built, swamped the 305 228HP to a built 350. That shows my age:eek:

RE: 454 upgrades
 

Thanks for the reply.

new question is:

with all the proper engine components such as solid bottom end, recommended intake - dart?, Perf. RPM Airgap?, holley 800 cfm., Say something similar to the 168731 cam - rmbuilder spec., Roller rockers, 9.5 to 1 comp. and gill exhaust. Parts for a 496 what to expect on the conserv. side as far as trq. and HP.

what heads? with what you have listed as a cam RPM airgap would be good. go to the 741 cam, edelbrock victor or dart intake with good set of iron heads and you could get 550-575, go to edelbrock aluminum heads with same set up and break 600

The heads being used at this time are the worked over 049 casting's oval port 2.19's and 1.85's by Valako. We get these things to flow well and considering were under 500 CI and staying under 610 to 615 lift they will work fine. I used many of the dart recs and use to wedge them at this CI. Trq. and dyno results are amazing.

This is kind of a quick fix for this year. Next year I have decided to go to the 572's

Without going crazy and having a reliable piece that can run on pump gas, you can expect about 1.20 hp/ci with aluminum heads and about 9.5:1 compression. With a little more compression and a decent size cam, you could expect to see 1.27-1.29 hp/ci. Hope this helps, Eddie

496 times 1.20=595.2.thats nice.eddie ,thanks ,thats just about what i figured.:party-smiley-048:

If you're keeping those heads, then I'd just leave it as a 468. I'd guess that you'd only gain about 30hp/40tq by stroking it with all other things the same. Not worth it, especially if you're gonna go to bigger power next year.

i am ordering the sticks today from bob. he needs the flow results and i'll let him decide. on the CI route i go. years ago we had good results with the oval ports up to 496 CI however i'll have to dig for the data.

:food-smiley-007:

I guese my builders are not as good ! My dyno results were 500 hp max and 600 trq max. peaks around 4k (I think) 496 ci. Dynoed wet with stock merc center dump and water pump, sea pump and alt.Dart alm. pro 1s 310 cc elderbrock air gap 9.3 or so comp. msd dist. Dont have cam specs right now 750 demons .Should I be worried Can I get more or just build 540s they seem to be getting 700hp plus or so out of only 40 more ci what gives?

Have you talked to Jim Valako about the projected HP or his thoughts about going to 496's? When Jim and I did my 470's I was contemplating the same thing as you. We decided to stayed with the 454 base and I decided that I would put that money towards bigger cubic in engines in the future. We put together some solid roller 470's with his ported heads that put out 590HP.


Those are nice numbers for real world wet dyno #'s running accessories. Remember dyno racing proves nothing the real dyno is the boat and those #'s are read on the SPEEDOMETER! ;)

I think your carbs are too small and you should be making more HP. Your stock exhaust is choking the engines and most likely the cams are on the small end because of the stock exhaust and reversion concerns.

with those parts I would think your cam is TOO small. even a 731 cam should have atleast an 830 carb. I am gonna use the 741 cam with 9.5:1, edelbrock heads, edelbrock victor intake, and I think it'll need 950 or 1000 cfm carbs and make over 600 HP around 5600 RPM

Thanks guys Im going to look into headers next but wow...there damn near as much as motors.They say headers are better so I thought I would by headers even though I may not realy need them now but so as not to double buy if I ever go to bigger ci later.Any thoughts? And can I get my current carbs flowing better? These only have 5 hrs or so Thanks

Go with CMI's. THey are a good long term investment, and they will let you run more or less what you would put into that boat.

As far as carbs, I can get you custom Holleys built to spec for around $700 +-. Real nice units with billet base plates and metering blocks. 4150 flange and whichever size you want. This one is a nice 950 I have made and it cost me around $700

Just talked to Valako today. Jim is a great guy and does excellent work. I met him back in 1989 and have been friends ever since. He has a couple set of my heads right now a matter of fact. If there is power to be made somewhere Jim will find it. It may involve throwing a bolster seat or something out the boat though. ha ha.

We did talk today regarding the 496's and he feared for me knowing the way I run my boats. He has been beside me more than a few times in lake MI. I said the same thing to him that I might just wait and save for some bigger CI' engines.

Hey Rookie,
Do you recall what cam you ran in your 470's??? I think Jim and I were actually discussing your engines as I remember hearing about him doing some work for you on the board.

Let me know,
Thanks,
John

Cam size really has nothing to do with carb size. Carb size is basically determined by rpm and cubic inches. You definately don't need a 950 carb on a 454-502 unless you're turning it 6500rpm. 800-850cfm is plenty.

I agree.
http://www.paulfinkmotorsports.com/Calc_3.htm

This has always been pretty close for me with the exception of blown engines.

solid roller duration @ .050 252 / 264, lift 0.630" on a 108*.
I used my Barry Grant 750's and they were on the small side.

RE cam
 

thank you for sharing the specs with me. if you get a chance just let me know how well you liked it. likes / dislikes

once again,
thanks
john

Besides them being a solid roller with the little maintenance I like the cams. With my smaller carbs it idles surprisingly well, but it does have the presence that there is a respectable cam in there. I run Stainless Marine dry to the tips, jacketed TRS tails so I was not worried about reversion. With the heads that JimV hooked me up with I am very happy. I built these engines off of base Merc 425's with a dual plane manifold, and knowing that I have TRS drives. I really didn't want to build some big cube engines with huge torque to blow drives. (that will come later)

I have not had them to full power in the boat yet only on the dyno. I had some fuel delivery issues and didn't want to risk them. But so far what I have experienced with them is a night and day difference compared to my Merc 425's.