Author Topic: E/BGR Engine Build Thoughts  (Read 19940 times)

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Offline Dynoroom

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Re: E/BGR Engine Build Thoughts
« Reply #30 on: January 19, 2015, 12:54:56 PM »
This message bounced because of some safety feature again. Lets see if I saved it.....

Good advice on the connecting rods F/B.

Let me toss this bit of experience out there for others to consider.

back in the 1980's I worked in an engine shop that at the time did Nascar "Busch" series engines. Dale Earnhardt was one of our customers. Anyway, we would replace the rods in these engines after 3-4 races depending. I bought a set of used Carrillo rods from one of Earnhardt's engines. The Carrillo rods we ran used SPS 7/16" rod bolts and in my opinion are second to none. Anyway, magged them and ran them in Duane McKinneys Sundowner twin turbo Corvette for 4 years setting a record @242 mph. Then in my 1400 hp twin turbo small block for 8 years at Bonneville setting several records from 260 to 300 mph in a Firebird.
Mag the rods if they're good I'd use them. Any rod bolts smaller then 7/16 I'd chuck them and get new. In my case I knew the history of the rods & bolts so I was very comfortable with them. But the point is good used parts can work well at Bonneville.
Michael LeFevers
Kugel and LeFevers Pontiac Firebird

Without Data You're Just Another Guy With An Opinion!

Racing is just a series of "Problem Solving" events that allow you to spend money & make noise...

Offline Stainless1

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Re: E/BGR Engine Build Thoughts
« Reply #31 on: January 19, 2015, 08:19:51 PM »
Dang Mike, you might have almost put another race on them in that amount of time  :cheers: 
Stainless
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Offline gasblender37

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Re: E/BGR Engine Build Thoughts
« Reply #32 on: January 27, 2015, 08:09:32 PM »
More thoughts and questions......

Based on the two E Class scenarios below, which one would be the better choice from a piston compression height?
If I wanted to turn the engine at 8000-8500 RPM would I choose the lightest rod & piston weight or some other combo?

Bore          Stroke    # Cyl    Rod Length   Cu In   Deck Height   Rod Ratio   Calculated Piston Compress Height   

3.5512   3.250   8   6              257.52         8.937            1.85             1.312
3.5512   3.250   8   6.125      257.52         8.937            1.88             1.187

Excuse my ramblings....just trying to get a little bit smarter
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"Sometimes you get what you want and it is not what you expect."
"I reckon if this stuff was easy, everyone would be settin' records"

Offline fordboy628

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Re: E/BGR Engine Build Thoughts
« Reply #33 on: January 28, 2015, 07:12:35 AM »
More thoughts and questions......

Based on the two E Class scenarios below, which one would be the better choice from a piston compression height?
If I wanted to turn the engine at 8000-8500 RPM would I choose the lightest rod & piston weight or some other combo?

Bore          Stroke    # Cyl    Rod Length   Cu In   Deck Height   Rod Ratio   Calculated Piston Compress Height   

3.5512   3.250   8   6              257.52         8.937            1.85             1.312
3.5512   3.250   8   6.125      257.52         8.937            1.88             1.187

Excuse my ramblings....just trying to get a little bit smarter
Skip


OK, here is the part where it gets "complicated" . . . . . . . .

1)   Class displacement limit 260.99 cu. in, I calculate your displacement @ 257.52 cu. in. also, so 98.67% of legal displacement.    That's very good.

2)   Rod length/stroke ratios vary by 2%, probably not much there, plus the engine is blown.   No worries.

3)   With a shorter compression height, one might presume a piston would be lighter.   This is not necessarily true.   The weight (mass) can vary, based on manufacturer and/or application.    Generally, (as in normally aspirated) lighter is better.   For blown engines with high boost pressures, you definitely want to add mass (weight) to cope with the higher thermal loads on the piston.    Piston mfg's (or Dynoroom,) can advise you here.  Piston cooling may also be in order . . . . .

4)   8500 rpm with a 3.25" stroke = mean piston speed of 4604 feet/minute   high
                                                  = max  piston speed of 7232 feet minute    very high
                                          = max piston acceleration of 142,668 ft/sec^2    extremely high
      I have not calculated the rod load yet, and I want to suggest you consider a shorter stroke . . . . . .   OR, an rpm change as below:

5)   8000 rpm with a 3.25" stroke = mean piston speed of 4333 feet/minute   better,  5.9%
                                                  = max  piston speed of 6807 feet minute    better,  5.9%
                                          = max piston acceleration of 126,662 ft/sec^2    WAAY better,  11.2%
      And of course the rod load would be lower.    If it was mine, I'd run 7800/8000 rpm max.

For comparison, a 3.25" stroke Cup engine.    Keep in mind that Cup engines use very light components, are not blown and have very short service intervals . . . . .

6)   9500 rpm with a 3.25" stroke = mean piston speed of 5146 feet/minute   extremely high, 5000 is a typical maximum
                                                  = max  piston speed of 8083 feet minute    extremely high, 8000 is a typical maximum
                                          = max piston acceleration of 178,614 ft/sec^2    beyond extremely high,  150,000  is a typical maximum
      Very light weight (as in unobtanium) components and short service life are what makes this combination work.   The very thin rings and very tight ring grooves required
      to make this combo work, will work against you with a blower engine . . . . . .

7)   And of course the big question:   How much blower pressure or absolute pressure? ?


There are others on the board that have more experience than I do with blown engines.   I would seek out some further advice from them.
 :cheers:
Fordboy

edit note:    I added in some additional numbers for comparison, segments 5, 6, 7.
« Last Edit: January 28, 2015, 09:44:48 AM by fordboy628 »
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Offline gasblender37

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Re: E/BGR Engine Build Thoughts
« Reply #34 on: January 28, 2015, 09:06:43 AM »
Thanks fordboy. This is exactly the kind of info I am looking for.
Dynoroom. Would you please give me your thoughts?
Thanks,
Skip
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"Sometimes you get what you want and it is not what you expect."
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Offline fordboy628

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Re: E/BGR Engine Build Thoughts
« Reply #35 on: January 28, 2015, 10:13:32 AM »
Skip,

You are getting into a "zone" here, where "small" changes can have a big influence on the outcome.

This is why it is important to calculate the numbers, and make decisions based on information, rather than "guessing".
 :cheers:
Fordboy
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline entropy

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Re: E/BGR Engine Build Thoughts
« Reply #36 on: January 28, 2015, 10:27:46 AM »
Thanks fordboy. This is exactly the kind of info I am looking for.
Dynoroom. Would you please give me your thoughts?
Thanks,
Skip

I'm told that dynoroom makes a living out of giving that type of advice, maybe it would be best to call him?? :cheers:

Offline gasblender37

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Re: E/BGR Engine Build Thoughts
« Reply #37 on: January 28, 2015, 01:15:27 PM »
Thanks fordboy. This is exactly the kind of info I am looking for.
Dynoroom. Would you please give me your thoughts?
Thanks,
Skip

I'm told that dynoroom makes a living out of giving that type of advice, maybe it would be best to call him?? :cheers:

Please excuse my ignorance. I did not know that.
Thanks,
Skip
Skip

"Sometimes you get what you want and it is not what you expect."
"I reckon if this stuff was easy, everyone would be settin' records"

Offline entropy

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Re: E/BGR Engine Build Thoughts
« Reply #38 on: January 28, 2015, 02:27:15 PM »
Thanks fordboy. This is exactly the kind of info I am looking for.
Dynoroom. Would you please give me your thoughts?
Thanks,
Skip

I'm told that dynoroom makes a living out of giving that type of advice, maybe it would be best to call him?? :cheers:

Please excuse my ignorance. I did not know that.
Thanks,
Skip

Skip,
I wasn't trying to diss you, nope.   Sorry if it came across that way.
In a situation much like yours, Mike told me to call him saying that some of this stuff is hard to explain by tapping out text.  Much easier when there an active dialog going on.  He seems to love talking/tapping about this stuff!
Karl
Mike at 714-5723672

Offline Dynoroom

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Re: E/BGR Engine Build Thoughts
« Reply #39 on: January 29, 2015, 10:09:29 AM »
Karl is right, I do run my own engine building biz. But I have no problem giving MY opinions on engine design & development.....
when I have time. Typing long answers on the forum is not the best way to communicate sometimes complex answers to engine build questions either. So........
The quick answer to your question is QUIT worrying about the optimum rod length. Use the 6" rod as the compression height will work best as you develop the engine. You may also find (I have) that peak power engine speed can be reduced somewhat with a turbocharged engine at Bonneville. Remember you are creating your own air density, and more. This stroke length will have no trouble making power @ 7500 rpm but can run well over 8000 as you develop the system. This is the same stroke Chevrolet used in it's 327" engine, and is also quite common in Nascar Cup engine packages.
I know everyone wants to build the BEST or RIGHT engine the first time. Good luck with that. If the engine type you plan to use has never been run in endurance type racing OR you are using parts that have never been tried before this will be a test. We all go to Bonneville and test our ideas, that's what you are doing too. To show yourself or your peers that your concepts & ideas are right.....
By bringing home a record trophy.   

Good Luck with your project  8-)
Michael LeFevers
Kugel and LeFevers Pontiac Firebird

Without Data You're Just Another Guy With An Opinion!

Racing is just a series of "Problem Solving" events that allow you to spend money & make noise...

Offline fordboy628

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Re: E/BGR Engine Build Thoughts
« Reply #40 on: January 29, 2015, 10:46:17 AM »
x 2
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline gasblender37

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Re: E/BGR Engine Build Thoughts
« Reply #41 on: January 30, 2015, 08:39:18 AM »
fordboy and dynoroom,

Thanks again for all your insight. I am a whole lot smarter than I was a few months ago.
"I reckon if this stuff was easy, everyone would be settin' records"

Skip
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"Sometimes you get what you want and it is not what you expect."
"I reckon if this stuff was easy, everyone would be settin' records"

Offline revolutionary

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Re: E/BGR Engine Build Thoughts
« Reply #42 on: February 04, 2015, 12:06:51 AM »
My 2 cents, if you are running forced induction, go for the extra compression height. You will need the strength and cooling of the additional volume.
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Offline fordboy628

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Re: E/BGR Engine Build Thoughts
« Reply #43 on: February 04, 2015, 08:01:00 AM »
My 2 cents, if you are running forced induction, go for the extra compression height. You will need the strength and cooling of the additional volume.

x 2
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline wobblywalrus

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Re: E/BGR Engine Build Thoughts
« Reply #44 on: February 04, 2015, 08:56:45 PM »
This applies to naturally aspirated motors and high rpm.  It pays to check the intake valve's flow capacity in relation to choke.  A fellow can spend lots of bucks to build a bottom end that can withstand rpm to find that the intake valve(s) size limits the revs.  The basic engine building software will help with this.  I use pencil and paper calcs or PipeMax.  There are fancier programs too.