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Author Topic: Inline-four crankshaft  (Read 106053 times)
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Jack Gifford
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« Reply #15 on: December 05, 2011, 02:31:53 AM »

... Need balance shafts etc...
... "cspeier"...  Might ask his thoughts...
... Might think DOHC...
I ain't gonna' mess with balance shafts.
I haven't looked at 'speedtalk'; got an email address for him?
My DOHC design is in-process.

Thanks.
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Jack Gifford
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« Reply #16 on: December 05, 2011, 02:36:26 AM »

... pretty much rules out your plan.
I don't have a plan yet. Thanks for the reminder about twisted forgings.
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Jack Gifford
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« Reply #17 on: December 05, 2011, 02:48:03 AM »

... very long rods and the absolute lightest piston helps...
... didn't mention Vintage motor, what are you thinking about basing the motor on?
Although long rods/low reciprocating mass is a concern for all engine configurations, thanks for reminding me- I'll need to try to emphasize that with this project- not easy with high-dome hemi pistons.
I'm not interested in the actual "Vintage" classes; just to give the appearance of a sixties-vintage lakester.
« Last Edit: December 05, 2011, 03:14:01 AM by Pontiac Jack » Logged

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« Reply #18 on: December 05, 2011, 02:59:45 AM »

Mmmm, since you don't have a plan yet, you may want to consider a Nissan RB26 6-cylinder as an option.
---
Guess I should add that the only requirements then is how you dress the engine. Developing vintage look exterior castings rather than a new engine from scratch that still isn't vintage. Hilborn looking EFI...
« Last Edit: December 05, 2011, 03:06:45 AM by Anvil* » Logged
Jack Gifford
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« Reply #19 on: December 05, 2011, 03:03:37 AM »

... The record your after is held by a turbo Offy that can produce over 1000hp...
... Unless you were really tied to what you want to do...
I don't know anything about the car, only that the record is 262. I'm surprised that it required an engine capable of 1,000 HP. The former N/A engine in my car dyno'd seven-hundred-something HP, yet showed 260-something on its GPS.

Yes, I'm "really tied"; see my signature line...

Thanks.
« Last Edit: December 05, 2011, 03:09:09 AM by Pontiac Jack » Logged

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« Reply #20 on: December 05, 2011, 03:17:28 AM »

... The record your after is held by a turbo Offy that can produce over 1000hp...
... Unless you were really tied to what you want to do...
I don't know anything about the car, only that the record is 262. I'm surprised that it required an engine capable of 1,000 HP. The former N/A engine in my car dyno'd seven-hundred-something HP, yet showed 260-something on its GPS.

Yes, I'm "really tied"; see my signature line...

Thanks.

I id not mean it had 1000 hp, only that a turbo Offy is capable of 1000 hp.  Tony
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Robin UK
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« Reply #21 on: December 05, 2011, 05:02:04 AM »

Jack,
Maybe worth searching out some technical articles on 80s F1 engines. Here's a link to a bit about the 1500cc turbo BMW F1 engine from the 80's. Based on the M10 in-line 4 production block it was developed to produce 1300/1400bhp in qualifying trim and 900 or so for the duration of a race. F1 doesn't allow alky or nitro so it ran on gasoline with some weird additives to help produce the power and keep the engines together - sometimes. This was also the ground effect era and I remember watching the cars go out on a qually lap surrounded by a brown haze and a pungent smell. It was terrifying and awesome it equal parts. When BMW pulled out, the engines were picked up by Megatron Inc who provided them for another year. The Hart 415T in-line 4 was not far behind in power - also 1500cc - but based on a custom block. Mechanical valve control was an issue at ultra high rpms (20,000rpm at one point a couple of years back) which the F1 designers eventually fixed by using pneumatic valves rather than springs.

http://www.gurneyflap.com/bmwturbof1engine.html

Cheers
Robin

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« Reply #22 on: December 05, 2011, 08:10:05 AM »

... Need balance shafts etc...
... "cspeier"...  Might ask his thoughts...
... Might think DOHC...
I ain't gonna' mess with balance shafts.
I haven't looked at 'speedtalk'; got an email address for him?
My DOHC design is in-process.

Thanks.
Although I have an email for him I don't think appropriate to publish it. However, I have attached here his website and if you sign in to Speedtalk you can send a PM. Tell him I sent you.

http://www.speierracingheads.com/

Somehow if the combo is right wouldn't think need the 10Krpm. Lot of blown small 4's making 1200 in drag trim and IIRC Ron Main in prior iteration of power in his liner had "detuned" the Ecofire 2 liter to "only" 800 for his 300+ runs. I don't have any experience modeling these things so don't know in your case.   And as you are running fuel class, there is always N20!
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Jack Iliff
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« Reply #23 on: December 05, 2011, 10:15:14 AM »

What ever you decide on make sure you have as many shoulder bolts as you can to hold on the flywheel. 3/8" dowel are good too.
Rich maybe able to comment on a balencer but I would suggest at least 2 full length keys for iwhich ever one you choose.........Good Luck
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Rex Schimmer
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« Reply #24 on: December 05, 2011, 05:44:56 PM »

Jack,
You have a much bigger problem than vibration if you are considering running a 3.58 inch stroke motor at 10,000 rpm, at that speed your "mean piston speed" is 6000 ft/min, most engine designers and builders consider 4500 ft/min the upper limit for performance engines that need to run longer than 10 seconds, i.e. such as Bonneville. I have seen several big block Chevys run pretty reliable at over 5000 ft/min but at the rpm you are looking at regardless of what style crank/rods/pistons you plan to have you are building a hand grenade. 

The equation for mean piston speed= 2xrpmxrod length(in inches)/12= mean piston speed in feet/minute.

Rex
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« Reply #25 on: December 05, 2011, 06:22:12 PM »

Agree with Rex. Though I am having some valve spring issues have sort of forgotten about the piston speed. My 2.58 stroke is 4300fpm range at 10k.
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Jack Iliff
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« Reply #26 on: December 05, 2011, 07:47:51 PM »

Ref. Reply #24
Rex probably meant "stroke" instead of "rod length" in his formula.  The 6000 fpm number probably got him really concerned about the rods, leading to the misprint.
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johnneilson
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« Reply #27 on: December 05, 2011, 07:55:37 PM »

Not being a follower of NASCAR, what are the motor dimensions they run?
It seems to me that they live in the 9k rev range. Anybody?

John
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« Reply #28 on: December 05, 2011, 09:03:51 PM »

I recall the Nascar MAXIMUM bore is like 4.185". @ 358 c.i. you figure the stroke . ( I WORKED  today and drove SoCal freeways so I's a bit brain ded!)
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« Reply #29 on: December 05, 2011, 10:21:10 PM »

I thought something close to that. max 4.185 bore and 3.25 stroke = 357.7 in

so piston speed =4875 @9k and 5145@9500.

If memory serves, the pin placement and skirt design plays a ton into what will work.

I seem to recall that F1 motors at one time had issue with centrifugal force pumping the oil out of the crank throws and starving the mains.
The cranks are now cross drilled at a very flat angle (close to CL) to reduce starvation.

John

BTW, SoCal freeways leave you "Dain Bramaged", if you can avoid all the texting going on.
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