HP estimate?

[vkwalks39]

G'day guys, I have a small problem...If I was to spend $4k on a 253(red), How much HP, Am I looking at? To compare a 308. Here's what I want to do with my engine.....

Head work --ported, valves IN 1.85 EXH 1.54, Double valves springs,
--Street Terra Roller Rockers 1.65 ratio
Pistons ---Flat tops, moly rings,.020"thou oversize, 10.1 comp,
Lifters ---Anti pump ups, Double timing Chain,
Crow Cam --- 40/80--300-240-109-495", Lumpy idle, good power.Improved heads.
Oil pump ---Semi hi volume.

Quadajet 4 barrel carby. K&N air filter.
Electronic dizzy with MSD Blaster 3d coil.
Pacemakers extractors, comp headers, tri y's manderl bent. 2 1/4" exhaust.
I'm using a trimatic stage 1 with 2800 rpm stally. STD 10 bolt diff 3.08.

Now I just want to Horsepower that I'll be looking at for a 253..Or Will it be better to buy a 308 and spend $4k on it. This will going into my vk. I've already spend money on a 253 but that was rebuild with a mild cam and thats is it. I can used that in my vh.

Cheers Jason....thanks for your help.:whistling

 

[ari666]

well lets just say you got everything sorted really nicely for 4k. which i doubt you will cos you can easily drop 1k on your head, but lets just say you get 1:1 so 253HP. which isnt easy.

then you get a 308, mild cam, mild heads, etc. (exhaust etc you alreay have yeah?) then you will easily get 253HP. and have plenty of scope for more when you have more cash.

 

[Munz]

You will be better off putting a 304 in her with single plain and a decent carb or you can go with efi you'll have to deal with all the wires for ecu etc
If you go this way and can find a late model VS early VT 304 it will come with the roller block

Buy this book you'll find out heaps about these motors
How to Rebuild Hotrod + Holden 253 308 V8 Engine Book | eBay

 

[vkwalks39]

Munz i would like to stay with carby v8, cause, I have the cam that I put up, mate. :spot on:

Ari, so is it worth me buying a 308? Yeah, to new exhaust mate. So what you saying is I'll get 253hp from both engines! yeah!
I don't want to spend it all on a 253 and get, say? 280hp from a 253, When I'll get 330hp from a 308. With the same set up. I'm just guessing here, lol, This is why I'm asking for some advice, on which route to take... If you know what I mean....Cheers walks :thumbsup:

 

[304runner]

buy a 304 and drop it in. 4k will see it done if your good with tools. A VS 304 is factory cleared for a 355 stroker kit if you want to work on that in the future.

 

[ari666]

i tried punching in all the details into "desktop dyno" but missing a few pretty important cam details so it wouldnt give me a power graph.

my understanding of engines is such that hitting 1:1 is not easy. so for a bit of work to a 253 you can get 1:1 which will be 253HP, but for the same work to a 308 if you achieve 1:1 you will get 308. its real basic garbage i am sprouting here, but you get the idea.

because of the smaller piston in the 253, it actually becomes more and more difficult to achieve anything over 1:1 without having to rev the engine till kingdom come. whereas the 308 has a better bore/stroke ratio for delivering power within a reasonable range, which means easier to achieve power, and longer lasting engine. as the revs go up, the 308's torque is able to stay higher, thus delivering a cleaner and safer power curve.

its not to say you cant get a thumping 253. and also not to say you dont have to rev the **** out of a 308 to hit good power figures, its just easier and cheaper with a 308.

but yeah. anything you plan to do to the 253, you can do to the 308 for better gains. anything on the heads. anything intakewise. anything exhaustwise. anything ignitionwise cos they are the same engine. the only thing is the 308 has more volume.

 

[vkwalks39]

304runner, I'll like to stay with the old style 253/308's mate, I just finish rebuilding blue 253 with mild crow cam, 280-240-110-486 specs on the cam that I've put in. I had it running with NO mufflers, neighbours heard it, and didnt like...lol.. I can do the basic stuff to my cars...Cheers Jason

 

[ari666]

just to let you know i had a very similar cam in my 308 at first. got 110rwkw on the dyno. my mates ute got 88rwkw. so you can image we were not very happy with that :s

im assuming you have the crow cam 5616. 300 lift@lobe 240 duration @50 you realise that crow advertise their cams as times 1.65, so 300 lift is actually 480, not 495. although you did mention you were going with 1.65 rollers, which make it 495 (not that it makes a huge difference tho)

also to note: to get 1:1 for a 253 and 1:1 for a 308, the heads cant be the same. you will need longer runners and bigger valves for best effect on a 308. (1.94 and 1.6)


edit* wait, you first listed "40/80--300-240-109-495" and then listed "280-240-110-486" but i cant find either. closest is

56031
IN. 32/68
EX.72/28

280
280

214
214
110
0.486"
0.486"

which is actually 448 lift, not their advertised 486

 

[vkwalks39]

Ari, the cam i have got is a crow cam 5616 never been used, I was going to used it in the 253 but, Guy at wimmera machine shop told me that, if I used the cam, I'll need to strenght bottom end and run 2800 stally and without it. It will run like a pig. The low bottom end would be crap...My old man has a pretty tough 253, it has showned some 308's up.....lol...I'll run the 253 blue in my vh, And look for a 308 for the vk....Another question for you is, why cant you run hyd cam from early carby v8 and put it in efi v8, are they different motors? Thanks for your help too!!

 

[vkwalks39]

Yeah they are the cams that I have. bugger!! In the 253 blue cam is 5603 and the other one is 5616 as you know....lol