Biggest low block
#1081713
09/24/11 07:57 PM
09/24/11 07:57 PM
|
Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
OP
master
|
OP
master
Joined: Nov 2003
Posts: 5,160
Texas
|
What is the largest displacement you can get with a stock block low block.
Getting old just means you were smarter than some and luckier than others.
|
|
|
Re: Biggest low block
[Re: 440Jim]
#1081716
09/24/11 10:34 PM
09/24/11 10:34 PM
|
Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
OP
master
|
OP
master
Joined: Nov 2003
Posts: 5,160
Texas
|
Jim it would be a low deck street strip car and trying to keep the torque up and the rpm down, 6500 max on the rpm, 3500 lbs and torqueflite with 3.54 gear. Heads B1 original with 2.25 headers 11 to 1 compression roller cam and NSS Indy ram intake with 800 eddys. I was thinking square 4.375 x 4.375
Getting old just means you were smarter than some and luckier than others.
|
|
|
Re: Biggest low block
[Re: dannysbee]
#1081717
09/24/11 11:18 PM
09/24/11 11:18 PM
|
Joined: Aug 2003
Posts: 43,127
Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,127
Bend,OR USA
|
My pump gas 518 C.I. 400 block stroker(4.375 bore with 4.300 stroke) usually makes more torque than HP on pump gas  Last time on the dyno it had a set of CNC ported Indy 440-1 with a single 1050 Dominator, it made more HP than torque with those heads on it  B1 will probally flow more than the 440-1 do so you may see similar or better results, my car weighs 3450 lbs with me in it and has gone 10.03 at 133,5 MPH on Oregon non ethanol premuim pump gas with the air cleaner and mufflers on 4.10 gears and 12x29x15 slicks last time out  don't be suprised if the peak HP is above 6500 RPM and peak torque, depending on the cam grind, is above 5200 RPM BTW, I used a real long rod(6.800 BB Chevy style and sizes) and a very short and lightweight Ross custom piston, 456 grams, piston only I also have a 440 block with a 4.275 stroke it is a high compression race gas brackewt motor with a bunch of good peices, it makes around 71 more HP on race gas with the same heads as the 518 did on pump gas
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: Biggest low block
[Re: dannysbee]
#1081718
09/25/11 02:31 AM
09/25/11 02:31 AM
|
Joined: Jan 2003
Posts: 9,986
Frostbitefalls MN (Rocky&Bullw...
gregsdart
master
|
master
Joined: Jan 2003
Posts: 9,986
Frostbitefalls MN (Rocky&Bullw...
|
Quote:
Jim it would be a low deck street strip car and trying to keep the torque up and the rpm down, 6500 max on the rpm, 3500 lbs and torqueflite with 3.54 gear. Heads B1 original with 2.25 headers 11 to 1 compression roller cam and NSS Indy ram intake with 800 eddys. I was thinking square 4.375 x 4.375
If you plan on keeping the revs below 6500 or so, those heads are going to have way too much port area IMHO. Torque won't peak till about 6,000 rpm. My 528 pulls max hp at 6900 rpm with 440-1 heads, which are quite a bit smaller than the B1s. With the combo you propose, you would need at least a 6,000 stall converter to stay up in the power band.
You may make more ultimate hp with the B1 heads at 6500 rpm, but a well built motor with smaller heads will have already beaten you to the stripe by the time you get into the power.
If you plan on sticking with the B1 heads, allow them to rev to at least 7000 to 7200 rpm, and stay at 4.25 stroke for the sake of piston design. the pistons get pretty far out the bottom of the bores, beyond 4.25, and the ring pack starts to get too close to the valve notch, if I recall correctly.
Last edited by gregsdart; 09/25/11 02:39 AM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
|
|
|
Re: Biggest low block
[Re: gregsdart]
#1081719
09/25/11 06:20 AM
09/25/11 06:20 AM
|
Joined: Jan 2003
Posts: 16,923
NC
440Jim
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,923
NC
|
Quote:
If you plan on sticking with the B1 heads, allow them to rev to at least 7000 to 7200 rpm, and stay at 4.25 stroke for the sake of piston design. the pistons get pretty far out the bottom of the bores, beyond 4.25, and the ring pack starts to get too close to the valve notch, if I recall correctly.
That was what B1Ken was saying and he ran lots of 4.250" stroke low decks with B1 original heads.
+9.980 block deck height
-2.125 stroke/2 (4.250/2)
-6.535 rod length
-----
1.320 Piston compression height
If your block decks slightly lower, you will need slightly shorter pistons. And with the B1 valve notches, that CH works.
If you really want 572 CID, the RB block is the way to go (Megablock, World, etc).
|
|
|
Re: Biggest low block
[Re: dannysbee]
#1081720
09/25/11 06:29 AM
09/25/11 06:29 AM
|
Joined: Jan 2003
Posts: 16,923
NC
440Jim
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,923
NC
|
Quote:
I was thinking square 4.375 x 4.375
I am sure it can be done, but...
Things get marginal IMO.
B1 head valve layout and piston valve relief with compression height and ring pack location.
More stroke likes a longer rod, to avoid pulling the piston out the bottom of the cylinder at BDC, but uses even less piston CH. So the piston ring pack design will be the part that needs the most work, but calculate all the others (clearing the piston to crank counterweights).
|
|
|
Re: Biggest low block
[Re: 440Jim]
#1081721
09/25/11 06:52 AM
09/25/11 06:52 AM
|
Joined: Jan 2003
Posts: 16,923
NC
440Jim
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,923
NC
|
Here is the piston to crank counterweight calculation, put in your own dimensions. Quote:
As far as counterweights hitting the piston at the bottom of the stroke, the typical problem is the piston pin boss, ie metal below the piston pin. This thickness varies a lot from one piston design to the next. My Ross 99496 pistons have 0.150", Wiseco K296A35 have 0.220", my Venolias have 0.180". Everything must be checked at assembly for clearance, but this is the math:
CWmax = Counter Weight max dia
Pthick= Piston thickness below the pin
Pin = Piston pin dia
Rod = Rod Length
CWmax = 2(Rod - Stroke/2 - Pin/2 - Pthick - Clearance)
For example:
CWmax = 2(6.535 - 4.25/2 - 0.990/2 - 0.180 - 0.075)
CWmax = 2(6.535 - 2.125 - 0.495 - 0.180 - 0.075 )
CWmax = 7.32" dia
That happens to be the dia of the "cam cut" on a Callies 4.25" stroke crank counterweight for a BB Mopar.
Depending on the bobweight the counterweights can be cut down pretty far. I cut my Callies 4.250" down to 7.14" with a 2185 gram bobweight.
The rest of the counterweight can be larger since it isn't at BDC. My Callies was cam cut from the factory at 7.55"/7.32", but I cut it down to 7.14" dia (round) and balanced at 2185 gram bobweight. The balance shop went between the lathe and the balancer to get this close, don't just use my dia with other cranks and bobweights.
Another example:
CWmax = 2(6.535 - 4.375/2 - 0.990/2 - 0.180 - 0.050)
CWmax = 2(6.535 - 2.1875 - 0.495 - 0.180 - 0.050 )
CWmax = 7.24" dia
But the 6.535 rod with that stroke might not be a good idea. And it would need a piston CH less than 1.258"
|
|
|
Re: Biggest low block
[Re: abodiesonly1]
#1081723
09/25/11 12:16 PM
09/25/11 12:16 PM
|
Joined: Jan 2003
Posts: 16,923
NC
440Jim
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,923
NC
|
Quote:
I think Koffel's has or did have a 553" low deck with B1's on it for sale.  
Is that a factory block (4.375" bore) or an aftermarket block (4.500" bore) ???
I agree Koffel's is worth talking to about B1 engines.
|
|
|
Re: Biggest low block
[Re: Twin Turbo Mower]
#1081726
09/25/11 09:48 PM
09/25/11 09:48 PM
|
Joined: Jan 2003
Posts: 16,923
NC
440Jim
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,923
NC
|
Quote:
I have a indy block 4.5 bore 4.375 stroke. My old setup had a 6.535 rod.
Was that with B1 valve reliefs or standard/Indy head valve reliefs?
As you have found, more stroke should have a longer rod, and that makes the piston shorter and puts the oil ring in the pin. But that is not a show stopper, just a compromise if that is what you must do. The B1 valve reliefs require the top ring farther down, so the ring pack gets tight/lower.
|
|
|
Re: Biggest low block
[Re: joshking440]
#1081728
09/25/11 09:55 PM
09/25/11 09:55 PM
|
Joined: Jan 2003
Posts: 16,923
NC
440Jim
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,923
NC
|
Quote:
you can get 572 in a lowdeck
The poster is talking about a stock block, and with a limit of around 4.380" bore, 572" is hard to come by... especially with B1 piston valve reliefs. 
|
|
|
Re: Biggest low block
[Re: Twin Turbo Mower]
#1081731
09/26/11 12:05 AM
09/26/11 12:05 AM
|
Joined: Oct 2007
Posts: 62
Waterford,NY
Vintage
member
|
member
Joined: Oct 2007
Posts: 62
Waterford,NY
|
I like the 4.25" stroke in the low deck. We have one with B1BS heads on it that makes a hair under 800 hp and we only dynoed it to 6700 rpms it was still climbing.I don't think the orig B1s are gonna like the lower rpms as much as a smaller head would. But I do like this engine combo it has gone 9.60s @139.9 shifting at 7000..
Last edited by Vintage; 09/26/11 12:07 AM.
|
|
|
|
|
