How much horsepower to expect?
 

All right all you gear heads and knuckle busters. I need some expert advice and I am sure some of you out there can give me some good advice. I have an '03 shell valley with a cleavor engine (351w block, 351c-2 valve heads.) I had it chassis dynoed. It showed 251 hp at 5000 rpm as its best pull and then started to fall off. I was a little dissappointed with the results. It seems everybody I talk to says that the cleavor is a good set up, they say that it builds its horsepower at high rpm's. It makes me think the engine is working against itself. I have a 444552 crane cam (this is what was recommended), the lift at the valve is 502/520, min rpm is 3000 max is 6000.The duration etc. I don't completely understand. I have a t-5 trans. 3.90 gears, ford 9, 4 link sus. It has stock rods, crank, and Keith Black flat top pistons, the block is bored a standard .030 over. The pistons have valve reliefs in the corner. Am I building enough compression? What horsepower should I be seeing out of this set up with the right cam etc.?

What are my best upgrades for better performance? I have thought about a Coast High Performance 427 stroker kit, but that means new aluminum heads, intake manifold, headers, stroker kit etc. about $ 5000.00 by the time I'm done. Would I be better to supercharge what I have? Any suggestions and comments would be helpful and appreciated.

The BIG question is...

Were you happy with the performance before you saw the numbers? If so, ignore the dyno numbers and enjoy your car.

There are a LOT better heads than the Clevelands for a 351W. I'd think that you could easily squeeze another 75 HP or so out of it with better heads and a cam matched to the CR & heads. But again, if the car felt good before someone stuck a number on it, don't let the dyno results spoil an otherwise enjoyable ride!

any4xx,

Very wise words indeed!!!

Cheers!
Dave

First off 250hp at the wheels is like 330hp at the crank, not shabby but not great either.

if the block is .030 over bore than you have 393 in displacement. You really dont need a storker kit becuase it already bored over. Next, your Cam is small and your heads could be better. You could get a new cam (Comp XE), heads (AFR they way to go here $1,400), and an intake (RPM Air Gap) then you could produce some serious HP. Like $2,300 in part total. Cam will determine HP and RPM in that setup.

No he doesn't. He has a 357 in cubic inch displacement

Yep, 393W is a 3.850" stroke.
Larry

I'm not as happy as I would like to be with the performance. What about a supercharger? What is the maximum CR with a supercharger?

A supercharger will cost you more than the parts that Bignoze has chosen, which sounds like he has a good plan. CR for a supercharged engine is around 8 1/2 to 9-1. You can't tell from your engine parts how much compression you have. You will have to either pull the engine and have someone do a liquid cc test or maybe see if you can find the person who built your engine and maybe they could tell you.

there are at least 75 hp in your car right now. Change the heads to some ported Trick Flows, maybe the intake (you did not say what you have) and prolly the cam too and you will end up with a 400-450 hp car.

Just find out what pistons you have and what deck height they are installed at so you don't end up with a CR that is too low or too high.

Thanks for the insight. I have a 351 street boss intake (because of the big block heads, small block configuration) So I will need to swap out the intake. Will I need to replace the pistons as they have valve reliefs for the big cleveland valves? I will need new headers as well.

A 351W bored .030" results in 357 cu in unless it has been stroked which was not indicated.

My 351W (357 cu in) has a Comp solid lifter flat tappet cam, flat top Weisco pistons, Ford "M" heads, roller rocker arms, 750 dp Holley, Edlebrock duel plane intake, etc, etc. The heads were just cleaned up, not ported. This engine produced 472 hp at 6300 rpm and 440+ lbs of torque around 3500 rpm, which is more than enough for the street.

It sounds to me like there should be quite a few ponies still untapped in your engine.

Wayne

Wayne,

It sounds like you have a very similar setup as I do what is the grind # on the cam.

Clevors are supposed to make a lot of power. The little that I know about them is that they make their power at high rpm. ARe you sure you have the right cam for that set up? Maybe your power band is much farther to the right than your cam is capable of going.

Note he said 351c 2v heads. The 2v heads have bigger valves and ports than the windsor, but they also have larger chambers giving lower compression. The 351c 4v heads are the ones with the huge ports and valves (with small chambers) that make all the high rpm HP. According to one of the books I have:

''''''''''''''''''''''''''''''''''''351W'''''''''' '''''''351C 2V'''''''''''''351C 4V
intake valve '''''''1.84 '''''''''''''''' 2.04 ''''''''''''''''''' 2.19
exhaust valve '''1.54 '''''''''''''''' 1.67 ''''''''''''''''''' 1.71
intake port '''''''' 1.94 x 1.76 ' 2.02 x 1.65 '' 2.50 x 1.75
exhaust port '''' 1.24 x 1.00 ' 1.84 x 1.38 '' 2.00 x 1.74
chamber size ''''' 60cc '''''''''''''''' 75cc ''''''''''''' 62cc

sorry about all the ''''''' but it was the only way I could make it look like a chart, as it kept taking out all my spaces.

I suspect there are quite a few aftermarket heads that are much better than the 351C 2V heads

Determine your budget first. Cleveland heads are an interesting subject.

Your cam a 226/236 112/+5...about as aggressive as I'd want to go for a street 357. The exhaust is a little big, and Crane specs it as a forced induction cam (there for the big exhaust). However, that probably doesn't hurt much.

Tappet lift is .314 intake and .325 exhaust. However, your Cleveland should have 1.73 rockers, not 1.6. That is .545 intake lift, and .563 exhaust.

Net, there are better cam profiles, but not a big issue.

Cleveland heads where pretty advanced for 1970, with big canted valves and big ports. They are pretty mediocre by contemporary standards. However, some of the best aftermarket heads are for Clevelands and Clevors.

This includes the Engine Master Challenge winning CHI heads from Australia. For your combo, their smallest 185cc would probably be best. You will need their intake also. With shipping (from a US distributor such as Porting Dynamics) your probably looking at $2700 or so.

When assembling, you need to watch the compression ratio. You didn't indicate your deck height or gasket thickness. With a carb, I guess you are looking at 10:1 to be safe. And you would like to keep the quench to around.040. With the dimensions, the head distributor can mill it to get the right chamber volume. You will need to measure the intake and exhaust pushrod lengths after assembly and order the correct length ones.

Since it is a Cleveland replacement head, I believe your exhaust manifolds should line up fine.

As was indicated, you probably have 300hp or so already. This may take you closer to 400hp. More is possible with a cam change. However with a carb and nothing to detect detonaton and pull timing, you are not going to get the 450-500 rear wheel horsepower some 347 LS1 Chevies get on pump gas.

One note on camshafts. Most of the catalog cams are flat tappet designs. It sounds like a hydraulic roller would be a good selection here. Comp can make a custom setup with their XFI lobes that would work well. Since there is no emissions issues here, you could tighten the lsa and end up with something like a 224/228 110/+4.

Thanks, David NJ, that was the type of nuts and bolts info I was looking for.

Similar setup to mine so this might help:

http://www.clubcobra.com/forums/show...highlight=dyno

Your motor sounds down on power for some reason. I don't know what other components you are running so I will just let you know that I am running a toploader and a jag irs.

The CHI heads are GREAT! If you go that route, use the cam they recommend.

I have changed to a blue thunder intake, added a msd 6al, 650 speed demon with a matched 1" four hole spacer and the crane 524422 from the specs in the above link. I has not been on the dyno since but I know it is running stronger then before.

I've got a 393W stroker, but I'm running KB 9:1 pistons and Roush 200 iron heads. Edelbrock performer RPM intake, Performer 700 cfm carb, and comp cams with .541/.544 lift at 286/294 total duration (dur @.050 is around 246 but don't quote me on that). Mostly stock bottom end, but running MDS ignition and distributor. She made a consistent 360 rwhp and 400 lb ft torque rather easily. I say go to a decent set of windsor heads and a cam mated to work with it and like the others have said, you'll seen an additional 75 hp. The AFR's would do you well, and there tech line will tell you what cam to run, but they run around $1400 where with the Roush 200 iron heads, you'll be looking at around $1000 assembled. There's my 2 cents worth. Good Luck.
Jim