427 bbc hp guesstimate
 

I'm currently putting together a 427 big block for my '74 and would like to know how much hp yall think it will make?the specs are these.
454 block bored 30 over with 427 internals.
Gm crank and rods(stock stroke)
trw dome top pistons part#l2239nf-30
comp cams magnum 292 cam
049 heads with 2.19/1.88 valves no port work
comp cams magnum roller rockers
holley dominator intake
i plan on using a 850 dp carb?
Comp ratio not sure but i think it should be @ 10.5 to 11.the heads were milled a little but not sure how much,the block was also decked but not sure either i know it wasn't zero decked though.i know its hard to guess with out comp ratio but i would just like opinions from yall and wat yall think about the combo thanks a lot.

Re: 427 bbc hp guesstimate
 

425-450?

Re: 427 bbc hp guesstimate
 

i outta have some good top-end! I don't think 450hp is too far off.

Re: 427 bbc hp guesstimate
 

Wow, I was just about to post the same question for my motor! We have a similar setup. I wonder if my heads will make much difference in the HP numbers.

Here's mine:
454 .030 over with stock crank and rods
Speed-Pro Pistons
Comp Cam 292H (.550 lift 244 @ .050 on intake and exhaust)
Edelbrock Performer RPM Marine Heads (2.25 int 1.89 ex, 110cc chambers, 290cc flow)
Edelbrock Performer RPM Air Gap Intake - Nascar edition :)
Comp Aluminum full roller rocker 1.7
850 Carb - considering Mighty Demon

Not sure on deck height but it's not zero. Compression ratio with these heads and pistions is 10:2 on paper.

Any guess on what this will make??

Re: 427 bbc hp guesstimate
 

AusTx your combo is even closer to the motor i'm building :lol:

Glad someone else is on board with the E'brock Marine heads! I got a set myself, here's my combo (and yes, those heads will make a big difference over the GM 049's). AusTx, are your Speed Pro's domed? The only domed piston I found recommended for the semi-closed chamber E'Brocks are made by SRP (JE). I'm gonna run a set in my 468, they are -23cc small domed, and come out to around 10.1 with a .039" thick head gasket. My block is going to the machine shop tomorrow. here are my hard parts

E'Brock BBC Oval port Marine Heads, Crower valvesprings
E'Brock Air Gap intake
Crane full roller rockers
Comp Magnum pushrods
comp X4 278 cam, 234/244 duration, .564/.575 lift
Holley 870 Street Avenger, 1" Moroso open spacer
SRP forged slugs
Stock 'truck' rods (polished beams, ARP bolts)
Stock crank, ARP studs in bottom end

Check out this build in car craft: http://www.carcraft.com/techarticles...evy/index.html

I was hoping to get at least the 530hp they got with the dual plane, maybe more since I'm running a little more cam, and bigger intake valves.

Re: 427 bbc hp guesstimate
 

man their is so many variables to take into effect... where do you live? volumetric efficincency, if you was to take best case scenario i would personaly say 450-475 but to the wheels is a different case, if you want to know those numbers what trans are you running? and theirs allways the tuning capabilities of yourself or whoever is doing it, timing, jetting... you want solid numbers DYNO IT AND TUNE IT. its saves the hassle of street tuning and you know for sure what it makes. just my half cent worth.

Re: 427 bbc hp guesstimate
 

Thanks for yalls opinions guys!i was hoping for like 500 maybe but these numbers dont sound bad at all.AND BESIDES I KNOW THIS MOTOR WILL MAKE MORE THAN ENOUGH TORQUE TO FRY SOME TIRES ON THE STREETS.

Re: 427 bbc hp guesstimate
 

Have the heads ported and that should get you close if not over. (if done properly)

Re: 427 bbc hp guesstimate
 

before i installed the heads on the block i asked that question here, if i should get the heads ported or not and almost everybody told that it wouldn't be worth it. That i wouldn't even notice the gains if any so i didn't port them.

Re: 427 bbc hp guesstimate
 

and that is true. the only way to really port heads is by doing it with a flowbench and having someone who knows the art AND science behind it. Don't get me wrong, there's nothing wrong with a backyard done gasket match and light cleanup/bowl blend, but a full on port job is a different animal, and is the only way to get real measureable results. You can't just grind away with a dremel and expect 50hp when you're done. The 049's are good heads and I think you have a solid combo put together. As said before, invest some time in tuning and setup and you'll be happy in the end.

Re: 427 bbc hp guesstimate
 

Boss, here is the piston I'm using:
http://www.summitracing.com/parts/STL-H693CP/

I just got my heads back today and hope to check piston/valve clearance sometime in the next few days. Your SRPs are -13cc piston head volume? Do you think the -22cc will be a problem?

Re: 427 bbc hp guesstimate
 

I wish I could tell you that! The EB heads are a 'semi-open' chamber at only 110cc. Not saying the SRP's are th ONLY slugs that work (the article I posted used Speed Pro's) but 22cc's is a good sized dome with a small chamber head. All I can say is measure, measure, measure test fit and measure again! No one wants to slam pistons into a valve! I am curious to see what you find out. I'm taking my block in this week for machine work, so hopefully I'll be putting my junk back together soon and can let you know what I find.

Re: 427 bbc hp guesstimate
 

so wat do you think it will be the best way to tune it?on a engine dyno before i drop the motor in or a car dyno after the engine is already installed?and which one you think would be cheaper?

Re: 427 bbc hp guesstimate
 

I would either track tune it or chassis dyno it. engine dyno's are good for getting a baseline, but it will respond very differently when you drop it into the car with the weight of the car, your torque converter, etc, acting on the motor. There are a lot of variables you won't see if you just run it in on an engine dyno. Of course, if all you care about is telling people you have a 500hp BB, you can stick it on an engine dyno and try to get that number - there's nothing wrong with that if that's what you want. But sooner or later someone is going to ask you what it runs in the quarter! It really just boils down to what you want, a quick street car or being able to say you have xxx hp.

Plus track tuning is WAY more fun and probably cheaper unless you break something!!

btw, is this motor going in the truck in your avatar? what's the rest of your setup?

Re: 427 bbc hp guesstimate
 

That's BS.

Properly ported (not a backyard hack job) heads are worth it. Certainly the 049 and 781's, they pick up nice power from minor clean up. You could gain up to 50hp for sure.

Re: 427 bbc hp guesstimate
 

btw, is this motor going in the truck in your avatar? what's the rest of your setup?[/QUOTE]

YEAH THIS MOTOR IS GOING IN THE TRUCK ON MY AVATAR. FOR THE REST OF THE SET UP I PLAN ON RUNING A TH400 WITH A 3000 TO 3500 CONVERTER, POSI REAR END AND LIKE 4.10 GEARS.I DONT PLAN ON DRIVING THIS TRUCK ON THE HIGHWAY JUST STREETS AND EVERY NOW AND THEN TAKE IT TO THE TRACK.

Re: 427 bbc hp guesstimate
 

how much do you think a good port work runs? And who would you recomend?

Re: 427 bbc hp guesstimate
 

Listen, I'm located in Canada and there are a couple in town that do decent work. I have no clue who would be able to work on your heads in your area. Don't spend a fortune just have them cleaned up.

OR bolt 'em on and upgrade to some nice aluminum ones later.

Re: 427 bbc hp guesstimate
 

well i already have the heads torqued on the block so yeah i guess i could upgrade to some better ones later on.

Re: 427 bbc hp guesstimate
 

With that small hydrolic cam no way will you see 450-475hp

to get into the 500hp you need to go with either solid lift cam or a full roller cam and when you do that you better get a set of H-beam rods (4130 steal) and a good set of forged pistons if you want it to last

My dad lives in east texas if you want to get any advice a real estimates he build about 30 high performance motors a year

let me know