XXO/BVGC '38 Chevy Coupe Build

[BoredAndStroked]

When you turn the pump, you can feel the vanes rubbing, so I have to believe there is some damage, even though there was no metal in the filter.

I believe the Barnes pump stages are gear driven - if you feel rubbing/binding, then there is probably something fubared with the shaft . . . guess we'll find out.  They assembled it - would have been nice if they actually used lock washers, lock-tight, etc . . . obviously the bolts to the water pump didn't do the trick! 

[38flattie]

When you turn the pump, you can feel the vanes rubbing, so I have to believe there is some damage, even though there was no metal in the filter.

I believe the Barnes pump stages are gear driven - if you feel rubbing/binding, then there is probably something fubared with the shaft . . . guess we'll find out.  They assembled it - would have been nice if they actually used lock washers, lock-tight, etc . . . obviously the bolts to the water pump didn't do the trick! 

Not gears Dale-3 lobe rotors.
 
 
Ok, guys-I'm looking for a little experienced advice here! I'm starting to put the plan together for the 'new, improved' version of the Flatcad, that will be implemented this winter. These include a roller cam, new forced induction system, flow work-head work, new ignition with engine management, etc.
 
I'm looking for ways to further strengthen the block, without having to go the expensive, time consuming act of a 5 main setup.The block already has billet mains, a very heavy crank girdle, and a crank girdle snout support.
 
How can I make the bottom end stronger still? Pin the mains to the block? Cryogenics? Redesign an exotic 4 bolt main?
 

[38flattie]

Some of the dyno results from last week.

[SPARKY]

45 deg side bolts into the main caps from the std girdle?  I would look at compression instead of tension

[maguromic]

x2 what Sparky said, I would also pin the caps and accommodate for a slide hammer to pull the caps, this is what we did with the GMC. Tony

[BoredAndStroked]

x2 what Sparky said, I would also pin the caps and accommodate for a slide hammer to pull the caps, this is what we did with the GMC. Tony

Hey - I like the 'ghost main' girdle - is it made out of aluminum or steel?  I'd like to see what you think about one material versus another - would seem to me that materials with the same/similar expansion rates would be ideal --> steel girdle on cast-iron block, aluminum girdle on an aluminum block.

=====================

Design Details:

I'm the guy that designed and fitted the whole lower end setup -- modeled it all in 3D CAD and then Don cut/machined the parts.   He kept my design tolerances exactly on the mark - some of the best machine work in steel that I've seen.  

The main caps were left about .005 oversize on height and width.  I then used my surface grinder to precision size them for both height (for crush) and side-to-side width - they are spot on in the saddles . . . you have to tap them in with a brass hammer.  The main cap studs are 9/16 (high quality ARP stuff).  The thick steel girdle ties together the whole lower end and there is a 'crush fit' on the tops of the main caps.  We're picking up the oil-pan rails to tie the girdle to the block for extra strength.   The whole point was to reduce the chance of cap walk and use the whole bottom of the block for added main strength . . . we'll see if this works or not.

Truth is, we don't know where the weak areas are on this block.  Until we see what is happening with the bearings and if there is any cap walk (which I doubt there will be - given the crush), we don't know if any additional steps are necessary and where to apply them.  If we happen to see cap walk or movement, it is easy to add dowel pins and crap - but I'm leaning toward this not being an issue.   Frankly, I'd love to have the setup we have on the FlatCad on my flathead Fords (which is why I'm designing a 5-main girdle setup for the Ford - with similar structural strength, but that conversation is for a different day!).

Block Structural Strength:  My best guess is that the overall structural strength of the block itself will be our limiting factor (from a rotating assembly perspective).  If the pan rails and main stud threads and block structure can handle the horsepower, then we'll be okay - if they can't, then we have another whole set of issues to ponder  (and I have some interesting structural augmentation design ideas along that line  ).  

Cylinder Pressure and Deck:  An area where we're probably more at risk is the overall strength of the cylinder walls - just how much pressure can they take??? Who knows!  Block filling and staking may help - but that needs to be done before boring (need to review my sonic testing numbers for cylinder wall thickness).  Also, we'll need to see what the heads and the deck are doing . . . the deck itself could be another major issue for higher HP and boost.

Always fun to ponder ways to get more HP out of this beast - though I'm going to concentrate on this year and learning as much as possible about what this combination is actually doing.   Hopefully we'll learn more - without and disastrous consequences.  

Dale

[38flattie]

45 deg side bolts into the main caps from the std girdle?  I would look at compression instead of tension

x2 what Sparky said, I would also pin the caps and accommodate for a slide hammer to pull the caps, this is what we did with the GMC. Tony

Sparky and Tony, that is the main thing I'm looking at! I spoke with Corky Bell for a long time yesterday. He feels with the current setup, and a move to turbos, I could achieve the HP I'm looking for with 20.5 lbs boost, if we get the turbos sized to spool near their max efficiency.

Garry's testing of the heads, makes me think that if we followed up on the flow, that we may pick up more flow with a little 'tweaking of the heads. More CFM=More HP available without more boost. I also think that while we have a very good cam, some thought there could lead to some gains. The turbos themselves give some extra HP at the same boost, and port injection, along with fuel, engine managed timing, should help us combat detonation, while getting good HP.

 And I really like the idea of pinning the caps!

x2 what Sparky said, I would also pin the caps and accommodate for a slide hammer to pull the caps, this is what we did with the GMC. Tony

Hey - I like the 'ghost main' girdle - is it made out of aluminum or steel?  I'd like to see what you think about one material versus another - would seem to me that materials with the same/similar expansion rates would be ideal --> steel girdle on cast-iron block, aluminum girdle on an aluminum block.

Block Structural Strength:  My best guess is that the overall structural strength of the block itself will be our limiting factor (from a rotating assembly perspective).  If the pan rails and main stud threads and block structure can handle the horsepower, then we'll be okay - if they can't, then we have another whole set of issues to ponder  (and I have some interesting structural augmentation design ideas along that line  ).   

Cylinder Pressure and Deck:  An area where we're probably more at risk is the overall strength of the cylinder walls - just how much pressure can they take??? Who knows!  Block filling and staking may help - but that needs to be done before boring (need to review my sonic testing numbers for cylinder wall thickness).  Also, we'll need to see what the heads and the deck are doing . . . the deck itself could be another major issue for higher HP and boost.


Dale

Dale, There won't be a 5 main girdle next year- money and turn around time from Crower won't allow it, even if the design were to be done in time.

 I disagree about the caps not being an issue-At the HP we talked about the other night, I think the whole bottom end could become an issue .I still want to lighten the rotating assembly, and tie the bottom end together even more than we have.

AT 20 psi boost, I believe the deck and cylinder walls will be fine, and I think the top girdle is a plus in helping us keep the engine solid. I want to send the CAD engine model to the engineering company,after we come up with our proposed changes. We'll see what they think it will do, then dyno it to see if they are right!

You keep saying that "I have some interesting structural augmentation design ideas along that line", but you won't expand on the statement. I'm going to come up with a plan for the proposed changes, and the day after Speedweek, the engine is coming apart to implement those changes. Of course, if we end Speedweek early, it may not be with this block!

[DND]

Hi 38'

Back in the early fueler days Milodon made a 1" thick steel girdle that bolted to the pan rails and center cross bars held the 3 center main caps, with a little pre load on the fly cut top surface of the cap.

That might help your block, but you still have a 3 main crank that is only going to take so much load before it breaks.

My 2 c worth

Don

[maguromic]

BoardAndStroked, Nothing ghostly about the mains, it’s a 7 main setup for the GMC.  I originally wanted to make it out of billet steel, but Doug Robinson loaned me the pattern to his GMC girdle to make one.  It was a lot easier to cast it than carve it, so after consulting with many engine builders and people I respect I decided to go that rout.  I am not worried about the expansion rate and besides all the SBC aluminum blocks I have seen have steel billet caps.  My vintage race car has one and I have flogged it for over 10 years without any issues.  Also the Gurney oil pans from the stock block Indy days of the early 80’s had the front and rear caps cast with the pan with the center caps in billet steel and they held up fine for 500 miles.

I think the biggest issue you will have whether you use steel or aluminum is it will want to walk on you.   On my  GMC the caps and girdle are cross bolted, has dowels and is pinned.

Last week I was talking with Doug Robinson about oil pans and he said something very profound.  “When you are over 100 horsepower from the nearest guy whey worry about it”. Or what Don Ferguson told me about efficiency on a GMC a few years ago “Just add more nitro”.   

Now back to the heat wave (its HOT here) to finish some fab work.  Tony


SBC Gurney Indy pan

[Tman]

This is better than surfing porn!

[38flattie]

Hi 38'

Back in the early fueler days Milodon made a 1" thick steel girdle that bolted to the pan rails and center cross bars held the 3 center main caps, with a little pre load on the fly cut top surface of the cap.

That might help your block, but you still have a 3 main crank that is only going to take so much load before it breaks.

My 2 c worth

Don

Don,

If you look at post 1126, you'll see that is exactly what we have, only it's 1.25" thick, with a crush fit on the caps.
The crank is a heavy billet main-it will/should handle more than our HP goals.

Tony, that's a nice piece! I like the idea of adding cross bolts, dowels, and pins to the Flatcad.

[38flattie]

Here's a sneak peak of something we've been working on! It's not done, so check back on it soon!

http://www.flatcadracing.org/

[4-barrel Mike]

 

Mike

[Milwaukee Midget]

Well first off, congratulations on some pretty impressive numbers.  What is frightening is that you are doing it with only 3 mains.

But I’d check to see if there is a problem first.

Yeah, I know, you asked for "experienced advice" - would you settle for an outside the box thought?. 

I’d concentrate my efforts on the center – it’s the least supported.

Can you machine a girdle with the center cap integrated - one piece - and splaying out parallel with the webs? 

[Richard 2]

Outside the box. Why not tie the main girdle to the heads outside the block. With gathering bolts of some type.
Richard