Inliners International Forums General Discussion Hi Performance 320 HP 250 Chevy

Things seem to be going slow on the forum. Maybe this will help get you guy's fired up for the approaching winter.

This is not my motor, but I did supply the majority of the parts.
320HP and almost 290 TQ. The tq curve was almost flat after 2800 rpm. The max HP was also achieved at 6300, which is where the dyno was shutdown. The HP was still climbing. We figured it better for the owner to find the top HP on his own.

It will have a pretty nasty idle and is more cam than is needed for 300 HP.

The build:
250 bored .040
Honed with deck plate
Block zero decked with pistons
6" Scat rods
Flat top Ross pistons
Balanced rotating assy

About 10 to 1 compression

Head work included
1.94/1.60 valves
Bolt in HI-FLOW lump kit
New guides
Hardened exh seats
Milled .030
3/8 pushrods and guide plates
HD springs rated for upto 7000 rpm

1.75 Roller rockers

Cam By Crane, 224/230 dur @ .050 .550 lift

Dist- HEI built by Autowerks

Clifford Intake

Edelbrock 500 AVS carb

Full length truck headers

Valve cover and side covers by Autowerks

This engine was a blast to dyno and will certainly be fun to drive. It is going into a 1968 Chevy 1/2 ton pickup. Believe it or not, with a 3 on the tree!

The better runs are at the last 4 minutes of the video. The video could have been edited , but it was not fair to not show things that really happen during dynoing. There was one pull done with the camera in the dyno room. The camera shut off because of nothing seen moving, just lots of sound. Grrrr.

You will also notice in the video how hot air is not your horsepower friend.

http://www.youtube.com/embed/1p3-cAJrLCw?rel=0" frameborder="0" allowfullscreen></iframe>

I think many people truly overlook the potential of these engines too often in favor of the cookie cutter V8's.

Nice! Took a vacation day today and planned to clean up my shop. This is just the motivation I needed to get my latest 250 project uncovered. Thanks Tom!

If you delete the Scat rods, guide plates and substitute Z-28 springs and Offenhauser intake, that's close to my Nova engine. Oh and trade the tube headers for a set of cast Fentons.

Very cool!!!

I think economics come into play why so many go V8. Do a price list of the parts and machine work for that engine, to get to the 300HP mark. Do the same for a V8 (which even a GM crate engine has a 290HP engine for around $2000). That will answer why everyone typically uses a V8.

I wish you could make that type of power at or below the cost of a SBC. Heck we have 2 less cylinders... it should be cheaper! LOL

Scott i totally agree definately sleepers for our v8 pray imagine what a 292 with that work then turbo it;)

Josh, I want to put a monster turbo on a 292 for my Camaro before I start messing with any 12 Port Head combos. I've got an awesome EFI intake design almost finished also that would be a good combo for a turbo or without.

Are you doing injector style i am goin to be running a professional products powerjection 3 that i came up on for very cheap:)

Yes its going to be injector style, but with some innovative companion pieces to make it more compatible with a siamese head design.

Hmmm very interesting i can't wait to see that!

Heck i can't wait to get mine running

All I need to finish my motor is an aluminum timing cover. Hint hint.

Im working on it now.

I'll second that request!!!!!!!!!!!!!!

Tom,
Trying to Gonkulate this nice build, here is what I get so far:
* Using same head flows you had in your dyno series
* Approx 255 in 185 ex CFM at .500 lift
* For the cam, I guessed 112 LSA straight up (ICL=112) hydraulic?

Gonkulator says
Torq 293 at 4200
Powr 306 at 5900
So I must be missing some cam or airflow or something, can you fill in any details?

In any case, I think this is a great build, reaches that "300hp" level and without a lot of high-dollar stuff. I would guess a well built 250 with stock crank/rods/truckdamper would survive ok up to 6000?

Deuce,
You know the Gonk did not take in a few very important often overlooked components. The side covers were worth 5 hp and the Valve cover brought up the remainder of your lost HP.

Seriously, will get some more info on the cam and other possible variables the Gonk did not catch. Later. Going to go out to the shop and machine some parts.

Nice! I'm hoping to get my "good" OHC engine up between 250 and 300HP naturally aspirated, with low'ish compression for boost and then try and boost by way into doubling or more the HP.

Tom, I'm curious to why you used the 224/230 .050 crane cam instead of one of the comp cams you sell on your web site. Is it because you went with the 500 edelbrock? I am assuming the cams on your web are ground for a 390 Holley?

SilverBuick
Can't wait to see yours running. Your doing a great job putting it together.

Stan,
The Crane cam was used, the customer wanted a fairly bumpy cam.

My cams are ground to be more street friendly. Any size carb can be used with my cams. Just not so good to run anything bigger than a 600 with a 250-300 cube six.

A Holley 390 should just keep up with close to 300HP.

Thanks tlowe, I'm working within my skill set, which is mediocre at best, but it beats sitting back and doing nothing but writing checks or doing nothing IMO.

Wish I could get a bigger cam for my set up. I'm going to get the engine started on a used 1bbl ~175HP cam, and if all is going well I'll swap it out to a new 4bbl ~215HP cam. The good engine will probably start with the used 1bbl cam too, then my re-ground custom turbo cam, which is only marginally larger (duration and lift) than a stock 4bbl.

I'm hoping to get some wiring done on Sunday.

[/hi-jack]

All I need to finish my motor is an aluminum timing cover. Hint hint.



With fins, I hope! I love fins!

How about some drawings of a cover?

MBHD

Ok, i'll get back on it. Im getting distracted again with other things.