22 replies to this topic

[looznugtr]

Hi I am looking into doing a stroker motor.

I have a 173 block that has been sonic tested.

Came with all machining done for a stroker and ford 3.9 pistons.

I need a crank and I am onto a kit cullen 1 piece counter-weighted crank.

I am told they don't like "REVS" but this is not a problem.

The plan is to make as much HP/Torque up to around 5500 which is the rev limiter i had on my old turbo 202 setup. 330 HP.

What input can you stroker owners let me in on.

 

Thanks Matt

[Hell34]

I have spin mine to 8000 rpm with out any problems for over 20000 Km just need good cam and head work

[limo]

dumb question maybe but why use a 173 block? Can it be bored to same as 186 or 202?

[looznugtr]

NO it's a 173 red and it's how i got it. OD prefix

Has been sonic tested so i can only assume it's good.

Was build for a turbo project and block was chosen for its think walls.

It is 91.86mm which is smaller than stock 186 and 202.

Something tells me this block was chosen as it had a larger core....(HP 179x 186 and 202 all have the same core)

Why cant a 173 have the large core as well.

Well you might get close to 300hp with a rrv limit of 5500.prob a bit less.Being a stroker,its inherently unsuitable for high revs anyway.6500 would be a realistic limit to retain good reliability.5500 wont even work up a sweat.
Maybe a custon grind cam specific to the stroker
would be ideal,but off the shelf grinds for the regular sixes can give excellent results.You might try adjustble timing gears as advancing the timing will work a little better on the stroked motor.Due to the bigger cubes.you need to remember advertised power bands will fall by maybe 1000 rpm when installed in the stroker.You really need 50 thou duration of around 240 - 250 degrees to make good power at 5500.The old waggot 104 seems to work great,but im not sure if u can still get them off the shelf.Otherwise try camtech.Personally never been impressed with crow cams.Also u can run 1.6 rockers without incurring a lot of stress.due to the lower revs of the stroker.You will not need quite as much spring pressure as you would in an un stroked motor.
Basically the head is always the limiting factor with the power,so you need a good porter,unless you run a j zed head which flows well out the box.
Both the 9 and 12 port can give similar flow,but the 12 port should give more torque,and is probably preferable if you run webers or dellortos.If your just gonna run a holley,a 9 port will work just as well and is maybe less prone to cracking?Of course theres the 12 port alloy which saves you 20kg and will potentially flow a little better than factory castings.
And you should maybe run a bigger damper on the crank.A main girdle doesnt hurt.Not sure how they fit with the stroked crank?
Maybe consider custom headers.as the off the shelf ones are all 1.5 primaries.You might pick up a bit with 1 5/8 primaries,but its a fair bit of expense to get them made.2 1/2 in collector is beneficial once you get up around 300hp,2 1/4 is starting to restrict flow at that level.

Im just wondering what lets go if you oferrev strokers?

Rods?

Crank?

Pistons?

Block?

Why would a 9 port be less prone to cracking?

[Steve TPF]

There was recently a lengthy discussion on strokers here: http://www.gmh-toran...troker-6-crank/

 

Might answer some of your questions.

[looznugtr]

As for the heads cracking,i havnt cracked either type.Ive been told the 12 port heads were prone to cracking,and that is supposedly why yella terra made new cast iron replacements at one time.
In any event,yella terra say the alloy is 60% lighter than stock,which would equate to 15 kg less,if the stock is 26kg.I never weighed either,but aluminium is half the weight of iron so lets just say there is a worthwhile weight saving.
As far as what is prone to break at high rpm in a stroker,the same parts as in a non stroked motor.You need to consider the extra stroke plus the reduced rod length/stroke ratio means at 5500 rpm,your piston changes direction at TDC at the same rate as a 179 would at 6500 or 7000rpm.At 8000 rpm,you stroker rods and pistons are experiencing exactly what they would at close to 10 000 rpm if they were in the 179.
I can tell you your gonna reach your limit of power in a 234 engine by about 6500 rpm.Maybe it hangs together until 8000,but above 6500 the power will be falling.Mine made peak power at 5800,and thats with a head flowing 307hp and tripple 45 dcoe intake.If it hangs together at 8000 with carillo rods and forged pistons,good luck.but a holden head will run out off puff well before that point in a 234.But in any event the OP said he wanted to limit rpm to 5500,starfire rods and cast pistons like ACL race series will be just fine at those revs.

What was the stroke a prostroke crank made?