FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: blykins on September 21, 2018, 06:06:08 PM
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Got a small shipment of BBM blocks coming in hopefully in the next week or two. One of them is earmarked for a 465 cube bracket engine build for Steve Dodson's AFX Falcon.
Specs are:
*BBM block, 4.310" bore
*RPM 3.980" steel crankshaft
*Molnar 6.800" rods
*Custom solid flat tappet camshaft, 262/270 @ .050", 109 LSA, .640"/.660"
*Trend tool steel solid flat tappet lifters
*Custom Racetec flat top pistons, 12:1 compression
*BBM Tunnel Wedge intake
*Custom Quick Fuel 725cfm carburetors
*Trick Flow cylinder heads, ordered bare, assembled with small diameter dual valve springs and titanium retainers
*T&D roller rocker arms
We (collectively as a forum) have been struggling with good comparisons for these cylinder heads. The goal is to do an engine with really only the cylinder heads as the variable to at least get a feel for how well they do. I think the 390 I just dyno'd did pretty stinkin well for a relatively simple combination.
In this situation, I have a 465ci Tunnel Port engine that I can compare to. Basically the same compression ratio, same bore/stroke, same rod length, similar camshaft durations and LSA's, same carburetors, similar-ish intake manifolds, etc. That TP engine made 696 hp and 588 lb-ft of torque. I expect this one to be pretty healthy as well.
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Very interesting.
How much would the power loss be, if you lowered the compression down to say, 10:5 ?
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you've got my interest.
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Very cool! 8)
Do you expect about the same hp/torque levels as the TP engine? More or less?
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I’m really not sure....LOL
Got almost all the parts here and block is almost finished up on machine work. Heads are assembled and I’ve started checking bearing clearances.
I’ll try and post some more pics next week.
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Did you do anything to the ports or are they out of the box?
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As my buddy would always ask: Why start small and go big when you can start big and go bigger? (with the 3.98 crank)
Is it a part already in hand?
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As my buddy would always ask: Why start small and go big when you can start big and go bigger? (with the 3.98 crank)
Is it a part already in hand?
Larry, if it were a street engine that saw moderate rpm or just frequent high rpm bursts, I would agree wholeheartedly about throwing a long stroke in it. However, on a dedicated drag race engine that will see 7000-7500, I don't like going with the 4.250". I would rather have a larger bore and keep the stroke down as that lets me use a longer rod, a little more stability on the piston, and a lower piston speed.
There are combinations that I have earmarked over the years that I have really liked. In the Windsor/Cleveland/Clevor world, the 4.155" bore with a 4" stroke does really well for me, and in the FE world, the 4.310" bore with a ~4" stroke does well for me too. With the Tunnel Port build that I referenced up above, we actually did 3 iterations with that engine, trying different things. The 3.980" stroke made right at 700 hp. The 4.250" stroke made around the 720 hp mark. Increasing the displacement by 60 cubes only netted 20 hp, albeit we switched to a flat tappet on the 511 inch variation. This was a nice bump for a dedicated street engine, but it wouldn't have been something that I would personally choose for a drag race engine.
This particular engine belongs to a forum member and is going into an AFX Falcon.
(https://farm2.staticflickr.com/1909/45875035981_9856a2dc20_z.jpg)
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Did you do anything to the ports or are they out of the box?
Left them alone. I did that on the 390 that I built a few months ago as well just to see what they were capable of out of the box.
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Curious why flat tappets are speced vs roller.
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To eliminate having to use T&D race rockers. I won't use a solid roller on an FE without cutting the heads for the T&D race setup. The TFS heads have the rocker stand pads .300" higher and I haven't looked at where that would put me with having to cut the heads for the rocker mounting bars.
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Cylinder heads for this engine:
(https://farm2.staticflickr.com/1805/42198857454_7de2588e70_z.jpg)
As of right now, they are assembled with Manley springs and Manley titanium retainers. With the inners pulled out for break-in, we're at 100/280 for spring pressure. With them installed we're at 165/440. Trend tool steel lifters on a Comp nitride camshaft, with T&D street rockers.
If you've never seen how high the rocker stands are raised, this photo of an assembled set gives you a good idea...
(https://farm2.staticflickr.com/1834/43496745634_6c23cdbe2c_z.jpg)
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As my buddy would always ask: Why start small and go big when you can start big and go bigger? (with the 3.98 crank)
Is it a part already in hand?
Brent also mentioned in the initial post that this is for a bracket racing engine.
Seems to me once you make enough power to get into your desired time slot, why not build an engine that'll last forever?
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Brent is that Rocker Pad higher than the Valve Cover rail ?? … hard to tell in the pictures other than they look tall
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Brent is that Rocker Pad higher than the Valve Cover rail ?? … hard to tell in the pictures other than they look tall
Stands are higher than the rail at the back.
(https://farm2.staticflickr.com/1899/29456914847_bc57f5da0c_z.jpg)
Another pic: look at the passenger side.
(https://farm2.staticflickr.com/1819/44172740082_024c2a700c_z.jpg)
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I understand, but seeing you swapped to a flat camshaft with the 4.25 crank, that kinda throws out the apple to apple comparison on power level. I do see the point of piston stability when using a longer stroke.
My motor is a good comparison on stroke. I literally only added the crank and it went from 550 hp to 625 hp with same heads, compression and flat tappet. I only turn it 500 more rpm. Granted the 3.98 motor never saw the dyno but the ET numbers put it at 550 hp and it seemed to like 6K. The 4.25 crank leveled out at 6500 on power. I would like to have seen what the torque numbers increased from. I know that change made me add tire width in the back and change the chassis big time to enable it to get it to hook. My previous best 60ft was around 1.50. With the new motor, tires/chassis it was gone 1.41.
My shop eggs me constantly to put a roller in it and do some CNC work to my hand ported 1997 Eboks. I'm leaving tons of power on the table, but that takes money and it's not in the budget.
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I switched to a flat tappet from a roller on the TP build because the T&D street rocker stands were dancing around on the heads and were leaving fret marks. There was a lot of spring pressure on them. Unfortunately, switching to a T&D race setup on a TP head is not an easy task, so we went to a flat tappet with beehives, since it was a street engine and 700 hp is enough LOL
True, it won't be a true apples/apples comparison, but it will be close. I don't always consider a roller cam to be a power upgrade.
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You can make power with a flat tappet, but typically easier with a roller. Though everything else has to be upgraded to put up with it. Money, money, money.
Since mine is just a bracket motor I like reliability. I haven't had the covers off it for 4 yrs. It came off the dyno, put in the car and not touched since but a yearly oil change. With only a .63 flat tappet, it doesn't beat up valve train. I want to race, not work on it. I always say: If I was worried about power/going fast I would not have started with a 4600# car.
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You can make power with a flat tappet, but typically easier with a roller. Though everything else has to be upgraded to put up with it. Money, money, money.
Since mine is just a bracket motor I like reliability. I haven't had the covers off it for 4 yrs. It came off the dyno, put in the car and not touched since but a yearly oil change. With only a .63 flat tappet, it doesn't beat up valve train. I want to race, not work on it. I always say: If I was worried about power/going fast I would not have started with a 4600# car.
I agree 100%. On a bracket engine, there's a lot of reason to favor in terms of reliability. The right flat tappet combo should go for a very long time, but solid roller lifters and valve springs have a shelf life.
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Brent or somebody: Have you tried the needle-bearing less rollers?
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Yes, I've tried the bushing rollers.
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OK, I'm in at 684@7k.........What, no contest?
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Waiting on pushrods and then I'll be ready to go.
I'll probably do another guess the horsepower game....but you're not allowed to play, Eric. :)
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Brent have all the blocks spoken for. Leny Mason
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Leny, this block was from a shipment a few months ago. BBM has a shipment in port right now and should be on its way to BBM.
I have two blocks earmarked from that shipment but could probably get another one, depending on how many he’s sold so far.
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Will you see how much they will be. Thanks Leny Mason