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STROKER 6 CRANK

Started by _hypo hb_ , Feb 18 2010 10:57 AM

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187 replies to this topic

#101 _Bomber Watson_

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Posted 21 October 2013 - 09:46 AM

306 at the treads??

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#102 _Dansthemanow_

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Posted 21 October 2013 - 10:24 AM

Thats what the dyno reads, yes.It was a dynapak hub dyno.

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#103 _Dansthemanow_

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Posted 21 October 2013 - 10:49 AM

That HP figure is absolutely dreaming if its NA like it says it is.Cheers.

Im fairly confident hes not dreaming!

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#104 warrenm

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Posted 21 October 2013 - 11:34 AM

Very impressive figure. Any chance of putting the dyno sheet up?

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#105 _Dansthemanow_

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Posted 21 October 2013 - 01:13 PM

The short rod ratio you get with starfire rods means you get more leverage on the crank early in the power stroke,increasing the torque.It also gives more dwell near the bottom of the intake stroke,meaning you trap more mixture in the cyl at low rpm.You cant rev as hard before snapping your rod bolts,but you simply wont have to rev to make the same power as a stock stroke motor.That also means you need much less valve spring pressure,hence less stress and friction in the valve train.Also you can use increased ratio rocker arms which may not be so desireable in a 8000 rpm stock stroke motor!

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#106 _oldjohnno_

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Posted 21 October 2013 - 01:30 PM

I'm not suggesting any dishonesty but those numbers indicate a BMEP of around 200psi or a little more, which if accurate (and I'm not convinced it is) is very very impressive for a Holden six.

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#107 _Dansthemanow_

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Posted 21 October 2013 - 01:36 PM

Ill put the graph up in ths next day or 2.
I wouldnt mind seeing a stroker with one of those duggan remake heads on it!
But they dont come cheap,then again you dont have to do much in the way of porting them,so you save in that area.

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#108 _Dansthemanow_

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Posted 21 October 2013 - 02:27 PM

You also have the option of custom rods if you want longer,or you can adapt ford 200 rods to increase the rod/stroke ratio,which helps high rpm and maybe allows a bit higher peak hp.I think the shorter rod works for street or speedway engines.Also one should shoot for a crank with a fully counterweighted arrangement like the blue/black crank.Pro stroke used to supply the adapted ford cranks with steel weights welded on to improve the balance characteristics of the crank.This probably helps with both crank and block longevity,as sometimes it is vibration cracking parts more so than a basic lack of strength.Mine has the extra weights and has been smooth/reliable so far.Can,t say how a crank without the extra weights would compare,but you would imagine the extra weights reduce flex and vibration,which to me is far more important than response and overall weight,which becomes virtually irrelevant once the car is in gear and the crank has the rest of the driveline attached to it

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#109 _STRAIGHTLINEMICK_

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Posted 21 October 2013 - 08:18 PM

Found this on Ebay:
Holden 202 Knifedged stroker crank

Says: CRACKTESTED AND BALANCED HOLDEN KNIFEDGED 12 COUNTERWEIGHT STROKER CRANK ,3.375" STROKE
THE BEST STROKER AVAILABLE FOR YOUR HOLDEN 6.NEW 5.73"LONGER H BEAM CONRODS COMBINED WITH A KNIFEDGED STROKER CRANK PROVIDE A HIGH TORQUE AND FREE REVING ENGINE.ONE OF THESE STROKERS PUSHES OUR STREET REGISTERED FJ UTE TO A 13.40sec 1/4 MILE @100mph ON PUMP FUEL USING ONLY 6300RPM

Also: SAVE $200 IF YOU EXCHANGE YOUR BLUE/ BLACK 3.3 CRANK IN GOOD CONDITION(must be less than.010 "undersize)

Doesn't say anything about supplying a ford crank for the job, so it sounds like an off-ground holden crank. Could be worth giving them a call.

Why dont you ask the guy that does them ? There are many advantages with a long rod stroker in Holden sixes especialliy if you have to drive the car on the road. I 'm not going to get into an argument about it ,just come over and see for yourself .Only believe comments from people who have have seen the difference a long rod and a short rod engine ,shouldn't bag it until you you try it .

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#110 _Dansthemanow_

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Posted 21 October 2013 - 09:20 PM

Well I never said long rods dont work! Only that ive had more than impressive results with stock length rods in a long stroke motor,as the accompanying dyno chart indicates.Those figures were produced on 98 pulp,with full street exhaust running two straight thru mufflers in series.The green line is with an air box in place,the red line is with open trumpets.Now I have special filters which should give the same power as the open trumpets.

Now it is possible the dyno reads high,and I suspect all dynos deviate somewhat,but it is a good make of dyno and I know the operator didnt dial in any atypical correction factors.So unless the thing was just way out of calibration...

In any event I made very good power on 2 other dynos,and that was when the package was not optimised as it is now.So the short rods clearly dont ruin the performance of the engine.But thats not to say you could not maybe get even more horsepower with longer rods,but would the overall balance of power and low/mid range torque be as good?

EPSON007.JPG 167.31K 12 downloads

Those kw numbers are rear wheel,not flywheel.

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#111 _STRAIGHTLINEMICK_

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Posted 21 October 2013 - 09:47 PM

Ok that sounds like really good power ,the cylinder head must be good .Have you run it at the drags ? , from that we can calculate Moroso hp,which is actual hp in the car on the day from the vehicle weight and mph .

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#112 _Dansthemanow_

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Posted 21 October 2013 - 10:15 PM

Being that im in adelaide and weve had no operational drag strip for 10 years,well untill recently,I havnt run it down the 1/4.I did run the car with my old 192 motor for a best of 14.5 et.But I can tell you the current motor has a helluva lot more power and torque than the old 192.I would be very surprised if it didnt run in the 12's,and theres potential even for high 11's,but only putting it down the quarter is gonna show what it can really do.So when I finally get round to that,ill let you know.Failing that I might buy a g tech pro meter,which supposedly are fairly accurate.

Anyway,I think that strokers are not quite the waste of time some would make them out to be.Dont forget that for a given peak HP, the lower revs you make that power,the quicker the car is gonna be because the average power over the rev range will be higher for the lower revving engine.And as I mentioned,the lower revs mean you can run more lift and faster valve openings without your valvetrain disintegrating,which may give you a power advantage

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#113 _Bomber Watson_

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Posted 21 October 2013 - 10:35 PM

Its funny how all these stroker engines are to hot for the strip.

Cheers.

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#114 _oldjohnno_

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Posted 22 October 2013 - 06:43 AM

Don't need a dyno, 400 metres of straight road and a speedo is enough to give an accurate real-world hp figure. Also remember that those hub dynos dont't really measure rear wheel hp, from other cars I've seen that have been run on them they seem to be about 35 hp or so up. Not that there's anything shonky about it, it's just that most of the loss comes from the tyre/roller interface and the hub dynos bypass that.

At any rate those are very nice numbers; it must be a lot of fun. I'm surprised though that you run such low diff gears when there's so much torque on tap.

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#115 _Dansthemanow_

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Posted 22 October 2013 - 07:45 AM

Yeah the diff is too high for it,but thats just what i put in it years ago because a cut down salisbury lsd came up in that ratio.Its been a strong diff but not ideal ratio.
It is fun to drive,especially thru the hills.Its quite streetable,idles at 750.Even with 205 semi slick racing tyres,you just feed the right foot in second gear,and when you reach 3000rpm,the rear of the car gets all loose.If i got normal tyres on it,same thing happens in 3rd gear at 80-100kph.So yeah,you can have some fun.

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#116 _oldjohnno_

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Posted 22 October 2013 - 07:49 AM

The more I look at those curves the more I think that they are indeed legitimate, or at least close. To get that sort of torque at such low rpms would require small, efficient, individual ports (like a good 12 port) and a very well tuned intake. One of the signs of a well tuned intake (besides big peak numbers) is the presence of big holes in the torque curve when the tuning is out of synch, and that's exactly what we have here. It's an interesting engine that I'd like to know more about, and I suspect those numbers aren't too far off reality.

I'm not at all surprised about the traction - I've got one here with 4.44s that I doubt makes more than an honest 200 that is absolutely hopeless to hook up.

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#117 _Dansthemanow_

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Posted 22 October 2013 - 12:43 PM

Well I myself am not entirely convinced at the dyno reading,but i know its made just under 250rwhp on a dyno dynamics roller,and that was before the motor was even run in and not as optimised as it is now.And that dyno was rumoured to read low.So lets just say the power is up there somewhere.As I said,those figures might not be accurate,but then whose are?Plus i remember reading about a 234 stroker kn street machine that dynoed 250 on the rollers at 5000 rpm.
And yes the intake tuning is what gives it a big boost,which your not gonna get with a holley.The 3xdcoe setup works well with the stroker,as really the typical manifold + weber+trumpet gives too much runner length for a 8000rpm motor,but its about right for 5000 rpm.That big slab of mid range torque is largely assisted by the ram tuning effect.I was lucky that i,by chance ended up with trumpet lengths that compljment the motor perfectly.Later i tried shorter but only lost power.And being injected gives a bit more torque over webers.To really use the ram tuning effect,you need a 12 port head,or at least 9 port with dividers so you have each cylinder with its own isolated runner.

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#118 Steve TPF

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Posted 22 October 2013 - 05:57 PM

Why dont you ask the guy that does them ? There are many advantages with a long rod stroker in Holden sixes especialliy if you have to drive the car on the road. I 'm not going to get into an argument about it ,just come over and see for yourself .Only believe comments from people who have have seen the difference a long rod and a short rod engine ,shouldn't bag it until you you try it .

Mate, I wasn't "bagging" anything - I just posted that link because someone was asking about stroker cranks.

I don't claim any knowledge about strokers - I'm reading this thread for educational purposes.

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#119 _STRAIGHTLINEMICK_

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Posted 22 October 2013 - 07:44 PM

Mate, I wasn't "bagging" anything - I just posted that link because someone was asking about stroker cranks.

I don't claim any knowledge about strokers - I'm reading this thread for educational purposes.

My apologies mate,just chose your post as an example ,all good here.

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#120 _STRAIGHTLINEMICK_

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Posted 22 October 2013 - 07:53 PM

Its funny how all these stroker engines are to hot for the strip.

Cheers.

I run mine down the strip , its done over 60 passes and about 10,000 road miles over 6 years, no worries.

If you have a strip only car with a big 9 port head and it doesnt matter what you rev it to then it may be better with a short rod engine becaust the short rod will pull down quicker from TDC to get the port flowing .

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#121 _STRAIGHTLINEMICK_

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Posted 22 October 2013 - 08:05 PM

Don't need a dyno, 400 metres of straight road and a speedo is enough to give an accurate real-world hp figure. Also remember that those hub dynos dont't really measure rear wheel hp, from other cars I've seen that have been run on them they seem to be about 35 hp or so up. Not that there's anything shonky about it, it's just that most of the loss comes from the tyre/roller interface and the hub dynos bypass that.

At any rate those are very nice numbers; it must be a lot of fun. I'm surprised though that you run such low diff gears when there's so much torque on tap.

Yep if you get a gps a good straight 400m track ,From a standing start take note of the speed at the end of 400m .The et is not important when calculating true power ,this is calculated from the speed and weight . It takes a certain amount of hp to shift a measured weight to a certain speed over a 1/4 mile .This is real world hp in the car on the day.

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#122 _Bomber Watson_

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Posted 22 October 2013 - 08:08 PM

I run mine down the strip , its done over 60 passes and about 10,000 road miles over 6 years, no worries.

If you have a strip only car with a big 9 port head and it doesnt matter what you rev it to then it may be better with a short rod engine becaust the short rod will pull down quicker from TDC to get the port flowing .

Havnt we already had this discussion Mick?

I wasnt talking about yourse.

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#123 Steve TPF

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Posted 23 October 2013 - 08:20 PM

My apologies mate,just chose your post as an example ,all good here.

No worries. I've been curious about strokers for a while. Since the capacity increase is slight I've always wondered what the attraction is, and how/why they are supposed to give more power. I'd like to build a new engine for my UC sometime, nothing earthshaking, just a good motor with a bit more grunt than standard. Since it's a daily driver and I don't have any illusions about winning drag meets my requirements are modest: a smooth, driveable engine that delivers some fun in the 3-6000 range. Originally I was thinking about a (very mild) turbo motor, but if I could get the same result with a stroker it might be a better option. Fewer hassles with rego etc, and (I presume) a better response because it wouldn't have turbo lag. Longevity is also a bonus because I'm not the kind of person who wants to rebuild an engine every year - and I certainly can't afford to!

My current engine is a stock 202 with extractors and running straight gas - I'm probably lucky if it's got even 100HP at the flywheel. So it wouldn't take 200KW to make me happy: even 200HP would be fantastic (by my standards anyway).

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#124 _Bomber Watson_

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Posted 23 October 2013 - 08:23 PM

I would select Micks kit any day over one of the old cut and shut ford crank type ones PERSONALLY.

Cheers.

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#125 _STRAIGHTLINEMICK_

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Posted 23 October 2013 - 08:52 PM

No worries. I've been curious about strokers for a while. Since the capacity increase is slight I've always wondered what the attraction is, and how/why they are supposed to give more power. I'd like to build a new engine for my UC sometime, nothing earthshaking, just a good motor with a bit more grunt than standard. Since it's a daily driver and I don't have any illusions about winning drag meets my requirements are modest: a smooth, driveable engine that delivers some fun in the 3-6000 range. Originally I was thinking about a (very mild) turbo motor, but if I could get the same result with a stroker it might be a better option. Fewer hassles with rego etc, and (I presume) a better response because it wouldn't have turbo lag. Longevity is also a bonus because I'm not the kind of person who wants to rebuild an engine every year - and I certainly can't afford to!

My current engine is a stock 202 with extractors and running straight gas - I'm probably lucky if it's got even 100HP at the flywheel. So it wouldn't take 200KW to make me happy: even 200HP would be fantastic (by my standards anyway).

It is the combination of the longer rod and the small increase in stroke that makes the difference . The engine revs up quickly and smoothly like a 186 .