new engine build any guesses on power

[lineberrcasey]

im building a .060 over 350 ,4 bolt main,eagle crank and h beams. pistons domed but are .o35 in the hole with a thinner head gasket so compression should be around 10.5:1, using comp cams 305h [email protected], .560 lift on both sides since im using 1.6 rockers and i have dart iron eagles with 200cc intakes(going to be ported a little) and 72 cc chambers angle plugs , on top is a victor jr with a 750 ultra hp carb,....in a little bit im switching to a lunati custom grind with .619 lift and a gross duration around 298* with a 850 carb any estimates on power thanks guys

[Chevelle598bb]

It should be in the 430-440 range with the 305h cam in it. If the short block is not built yet I would bring it back to the machine shop and have the block milled to zero deck. You are loosing a ton of quench with the piston that far in the hole. You are already working with a dome piston that has a small quench but having the piston that far in the hole will give you no quench. At what deck height you have with 10.5 it will ping like crazy due to low quench.

When you go to the new cam I would keep the 750 hp you already have. Going to an 850 will gain you a few hp but nothing that you can really feel. For the cost of a new carb you can make those up else where such as the oiling system. Unless you spin it over 7000 an 850 wont gain much over the ultra hp you have.

[lineberrcasey]

the reason i haven't already had it zero decked is the compression would be to high unless i can figure out how to bleed some of it off with my camshaft profile DCR i think is what they call it

[Chevelle598bb]

If you zero deck the block and use a .039 head gasket instead of a thinner head gasket such as a steel shim then you will be at the same compression and good quench.

What cc dome are your pistons?

[lineberrcasey]

3.5 cc's

[lineberrcasey]

sorry i forgot to add it had a 3.75 stroke which adds a little to the compression sorry to leave that out

[lineberrcasey]

Shane at lunati cams told me the cam would put me in the 500-550 range at the flywheel i just wanted to see more than one opinion

[SkinsandJrfan]

I have a stroker that's .40 over with a 400 crank 305h cam. Iron heads with roller rockers. 750 dp carb and I'm pushing about 485hp. I was told that you take the cubic inches and multiply it by 1.25 to get your estimated hp rating. .40 over is about 388CI.

[Chevelle598bb]

There is a big difference between 500 hp and 550 hp. The motor will never see 550 hp with the pistons .035 in the hole and near .075 quench clearance. All of the efficientcy is gone. The heads do no flow enough to support 550 hp with 10.5 compression. With proper quench and 12 to 1 with a solid roller you could get there. For 550 hp with a 383 you need a 215cc runner head And a exhaust port that flows more than 177 at .600. With your current combo which is not optimized with the 305h you will not be over 440 hp. With the larger lunati cam which you have not give specs to you may make a tad bit more if it is a hydraulic or solid roller instead of a flat tappet. The issue is .075 quench clearance will ping on an iron headed 10.5 to 1 motor all day long.

One way to find out hp and that is a dyno.

[lineberrcasey]

thanks guys this is my first engine build so still learning all the time and i plan on getting a zero deck the new cam is a solid flat tappet 259/[email protected] lsa/icl 112/106 tight lash.014"/.016 im still in the planning stages of the full specs i need to do a little more research. how much could the head porting help my combo i already had the heads so i figured i would use them on this motor? plus also considering switching pistons and adding procharger when budget allows it

[lineberrcasey]

im not like most where i see a number in my head and have to have i just want enough to make my 3900 pound 70 impala move:D

[Chevelle598bb]

With a 259/267 cam you will have a powerband of 4500-7000 or so in a 383. Plus with that much duration and lift you will be eating springs and lifters on a solid flat tappet like crazy. Also with that size cam in a 383 you would want 12 to 1.

I always tell my customers to build their motors right the first time. I couldn't count the number of customers that tried to cut corners and then they were back to see me because their combo was not right.

First before we go further we need to figure out your goals. What are you trying to do with your car? Autocross, drag race, road course, cruiser? What powerband do you want? A stock style built sbc short block can take 6000 rpm all day long but you start throwing 7000 rpm at it an it won't like it. Are you going to run pump gas or e85? What intake, crank, rods, pistons, carb do you have. The more info the better.

[lineberrcasey]

well im trying to run the line between PT auto cross/drag racing and weekend cruising a powerband from 3000-7000 is what ive seen to have the best results with a sbc before, i plan on using 93 pump gas in combination with stp octane booster(or like a 3:1 mix with race gas i have a 26 gallon tank) im using a 73 camaro short block until i can afford a dart shp(to build 406 or 421) which should handle what im going for so mileage not really a concern if i can stay within 7-10 when driving normal as of now i have a victor jr eagle crank(not forged) eagle 6.0 h beams(bought from family) and i have thee Holley 750 hardcore grey ultra hp the pistons are forged icons with a 3.5 cc dome and i have the virgin dart heads which can be ported i appreciate your help greatly i already have a th350 with 3500 stall and th400 with a 3000 stall if that helps any too

[lineberrcasey]

it wont be spun to its max until i get the dart block

[Chevelle598bb]

It is not the block that is the issue at 7000 rpm. It is main caps, fasteners, rod length, compression height, forged or cast crank, type of bearings, clearances, oiling system and other factors.

Another thing I tell my customers is to not build a motor that will be used for another application later on down the road. For example, I had customer that I built low compression forged short block for forced induction application. He was going to run the motor for about a year before he put a turbo on it. Well between the low compression and turbo cam, the motor did not make the power he expected in N/A form. After a year and realizing that the turbo set up would cost almost what the motor cost to build, he brought the motor back and I built it for N/A application. If you are going to run N/A for the time being then build the motor for N/A. If you are going to run a F/I set up build the motor for F/I. Later down the road if you want to put a blower on the car, sell the current motor and build a F/I motor. You will be much happier.

Now as far as the converter you have, the car, weight and goals you are trying to get to the 305h is high on duration and the lunati cam is way too big. With the lunati cam you would need at least a 4500-5000 converter just to get out of the hole. The motor would be so peaky that it would be horrible on the street and you would have to run the autocross course at 5000 rpm and above. Also if you drop the compression to around 10 to 1 you won't have to mix any race gas with pump gas. That gets to be a hassle, expensive and the difference between 11 to 1 and 10 to 1 is about 4% hp when the correct camshaft is chosen.

If I had the parts that you have this is what I would do. I would replace the dome pistons with icon flat tops which would bring the compression down to 10.1 to 1 when used with the standard felpro 1019 head gasket and zero deck. Rebalance the rotating assembly and now the motor will be very happy with 93 pump gas. As far as the cam goes I would run a hydraulic roller such as a comp extreme energy 236/242 at .050, .555/.576, 110 lobe sep on a 106 lobe center. The cam would have a powerband of 3000-6200 or so and would work great with the victor jr and converter you have. Then just run the correct springs since you were going to have to change them anyways for the solid lifter cam. You would then not have to worry about valve train durability and cams going flat. I would then do some bowl blending and short side radius work on the dart heads. They can be ported and made to flow very well but they do not flow that well out of the box as with most sbc aftermarket heads. The motor would then run on pump gas, make much more torque throughout the entire powerband, get better mileage, idle better, drive better and make more power than with your current set up. Lunati also has some good hydraulic roller grinds too if you are partial to them. The Holley 750 ultra hp would be a great carb for that motor. I have got to play with quite a few and really like them for the price. You said you wanted 7-10 mpg, with the timing and carb set right I bet you could get 14-16 driving it easy. That's what I would do if the motor came to me to finish building.

I saw in another thread where you mentioned you were 18. Please don't take this the wrong way that I am getting down on your build but it is not a good combination. Just trying to help before you spend a ton of money an you are stuck with a motor that might as well be a boat anchor. Engine building is what I do. A lot of us older guys have been around the block or two and most have either run a motor with too much compression or too much cam. Yeah it sounds cool until you get spanked by a Honda. Lol.

[lineberrcasey]

i honestly thank you ive been working on mostly old drag racing knowledge and circle track because of my family like i mention i have a pretty good apptitude to work on cars but i don't know as much about the full on technical stuff like most i can put a motor together but that doesnt mean it will run at its full potential what else would you recommend oiling and cooling wise too

[lineberrcasey]

so as far as gearing goes taking in the weight and the cam anywhere from 3.73 to 4.11 would be decent for my combo right?