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.

[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.

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

[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 shit 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

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

[ari666]

you cant use a 308 cam on a VN head cos they have a different valve setup. i.e. 308 is intake/exhaust intake/exhaust exhaust/intake exhaust/intake whereas VN's are intake/exhaust intake/exhaust intake/exhaust intake/exhaust.

and attached just for a lOL
253.jpg


edit* cant read crappy pic. it says you will get 385HP at 7000 rpm...

[vkwalks39]

cool, that attached thing you put up....yep!! lol no idea lol......thanks for telling us about the vn heads set up to early heads.

[vkwalks39]

ARI is that for 253 or 308? the 385hp....If it is cool...This is the first time I've done something like this to my engine. My aim was to get more than 320hp from 253/308...Thanks heaps. If i have more questions i know who to ask, mate thanks again Cheers Walks... have a good one

[vkwalks39]

Um i forgot to put in a 1" spacer to, add that to my list as well....lol.....

[ari666]

My aim was to get more than 320hp from 253/308...

i havnt got 320HP out of mine yet needs a better intake and better heads. 150rwkw is closer to 280HP

[Blown V6 Hatch]

It's pretty simple really, anything a 253 can do a 308 can do better. Nothing "wrong" with a 253, apart from the fact Holden made a 308. Also, the more power you want to chase, the more angry the smaller engine will be. More cubes is sort of a free kick so to speak.

A well set up naturally aspirated street engine shouldn't have much trouble making 1 HP per cube.

[ari666]

Um i forgot to put in a 1" spacer to, add that to my list as well....lol.....

what intake manifold you using? and what kind of spacer is it? if its the open mouth kind and you have a dual plane manifold, itll actually make things run worse. i dont know for a fact why, but i tried it on my combo and it ruined all low down torque really noticably.



the one on the right is useless with a dual plane, simply cos' the air/fuel rushes through your venturies, then has an argument when it gets to the split in the planes as to who is going down which side. for a dual plane you need the type on the left (but the pic is for a holley and wont work on a quaddy) so all it does it extend the length of the runners from the carb buttterflys to the opening of the intake.

[vkwalks39]

ARI, manifold at the moment is a stock 4 barrel one... Later,probly edelbrock performance or torker, Which one dont know! lol the one that works well with the combo...Any suggestions would be great!! Running Quadajet 4bbl, size i dont know....

Spacer, I dont know the brand, cause, I've order it it hasn't come in yet! mine you I've ask this about 1 1/2 weeks ago!! bloody autopro!!!
So do you reckon the combo will go alrite? Ari.

Spent a whole day at the royal childern hospital, man that place is HUGE!! for my boy...Who's into v8's, he saw my cousin vh brock, he had the biggest smile that I've ever seen.......Cheers Jason

[vkwalks39]

Blown v6 hatch, cool mate, I think the 253 is a underdog, theres nothing wrong with them, to me they are a v8. ITS 253 that thing is a beast....Who knows one day I'll buy a 308, while I've a couple 253 laying around I might as well use them. Cheers Walks Have a good one!

[Blown V6 Hatch]

Blown v6 hatch, cool mate, I think the 253 is a underdog, theres nothing wrong with them, to me they are a v8. ITS 253 that thing is a beast....Who knows one day I'll buy a 308, while I've a couple 253 laying around I might as well use them. Cheers Walks Have a good one!

Don't use that car as an example....It's not even a 253 anymore, it's a 292. YT -3 high port alloy heads, Enderle mechanical fuel injection, big solid cam, 13:1 compression. Hardly your run of the mill 253, it's nearly a 308 and it's got some good bits on it.

[Warranty Void]

Street Machine mag did a 253 build up about 10 years ago, chasing 350 HP and got it quite easily without going mental with cash or mad compression etc. They did offset grind the crank though for more throw. It might be worth googling "street machine 253 build" or "little league 253" or phoning Dandenong Crankshaft reconditioners or regrinders I think they were called, as they did the build and probably still have all the specs.

[ari666]

fitting a 5.7 liter crank and boring out to .60 will make a 310CI why why the f..k would you bother???


vl walks, get the torker. dont bother with a performer. they are no better than a modded stock manifold.

[vkwalks39]

Ari, ok cool thanks for that. Still deciding on what to do? Buy a 308 or do the 253 up?....... ARI, I've got a question for you, My cousins vh brock hasn't been start for about 4.5yrs, the carby is not running probly we are going to put a kit into it, running real rough, and it's blowing out dark black smoke from the exhaust. Do you reckon just give it a GOOD services, and do the timing? Cheers Jason

[vkwalks39]

Warranty void, I remember that, something like 377hp or something like that! I might have look into that....Cheers

[ari666]

My cousins vh brock hasn't been start for about 4.5yrs,

my impala hadnt been started in 14 years (so i was told). tipped some fuel down the neck of the carby new battery and fired on about the 3rd crank ran like poop tho. changed plugs, cap and rotor. and ran much better. to this day i still have not touched the bottom end, just cleaned it all up, changed cam and lifters, intake and carby and it runs like a dream.

i guess itll depend on how much water has been sitting in the bores.

have a read though here: how to rebuild/ modify quadrajets (also vac hose diagram) i tried to cover pretty much everything. if you wanna rebuild the carby on it, it should help you muchly.