FE Power Cylinder Heads - Results with New Cam

[thatdarncat]

Jay,

What is the CI and CR on this engine?

Not Jay, but here’s a screenshot from an earlier post on the FE Power cylinder head testing which had the specs. As explained earlier in this post the cam & valve springs have been changed now. And here’s the link to this post:

http://fepower.net/simplemachinesforum/index.php?topic=9171.0;all

[frnkeore]

Jay, have you thought about adv the cam about 3*, it would give you a bit more dynamic compression.

Also, I would love to see the difference in the 850's vs the Dom's.

[JERICOGTX]

Very cool Jay! Nice work.

[blykins]

Jay, how difficult would it be to offer rocker arms in a 1.9-2.0 ratio?  Not only would that let the valve lift go up, but a higher rocker ratio accelerates the valve quicker off the seat as well. 

I think the new cam with an .880-.900" lift would be a big bump, but I also think that the port volume is small for a 510ci engine aiming for 900 hp and 7000-7500 rpm.  I'd like to see those heads with about 15-20cc added to the port volume.

[allrightmike]

That new cam certainly looks better.   More power with less duration is good.   It doesn't look like the old cam was the reason for the engine peaking around 6500 rpm though.

paulie

Paulie, I have to agree, although this new cam peaked a couple hundred RPM higher than the original cam that probably isn't the reason that the power is mostly flat after 6500 RPM.  I think at this point that the reason is the airflow capacity of the heads.  Horsepower means airflow, and with a cross sectional area that is only a few percent larger than a stock FE medium riser head, it may be that no more air can be crammed through there.  I do think there is more power in the 8V intake though, and I may yet get closer to 900 HP.  But even at this level, in a drag car with this engine you'd want to shift at 7500 anyway, because the engine would still be making good power at that point.  And certainly with a smaller engine the HP peak would be higher in the RPM range.

I will keep working this issue, I'd like to wring everything I can out of this setup...

  Jay, will you eventually test on a smaller displacement engine to prove your theory about port size being a bottle neck?

[CV355]

Dang, that is impressive!!

[jayb]

Jay, how difficult would it be to offer rocker arms in a 1.9-2.0 ratio?  Not only would that let the valve lift go up, but a higher rocker ratio accelerates the valve quicker off the seat as well. 

I think the new cam with an .880-.900" lift would be a big bump, but I also think that the port volume is small for a 510ci engine aiming for 900 hp and 7000-7500 rpm.  I'd like to see those heads with about 15-20cc added to the port volume.

I just checked on this and it wouldn't be too difficult to get to 1.85:1, or even 1.9:1.  Beyond that it's hard to say for sure, I'd need to have Bill run a strength and fatigue analysis, but there's enough meat in the rockers to go up to 2.0:1.

[blykins]

Jay, how difficult would it be to offer rocker arms in a 1.9-2.0 ratio?  Not only would that let the valve lift go up, but a higher rocker ratio accelerates the valve quicker off the seat as well. 

I think the new cam with an .880-.900" lift would be a big bump, but I also think that the port volume is small for a 510ci engine aiming for 900 hp and 7000-7500 rpm.  I'd like to see those heads with about 15-20cc added to the port volume.

I just checked on this and it wouldn't be too difficult to get to 1.85:1, or even 1.9:1.  Beyond that it's hard to say for sure, I'd need to have Bill run a strength and fatigue analysis, but there's enough meat in the rockers to go up to 2.0:1.

That would be cheaper than a big cam core.

[jayb]

Jay, will you eventually test on a smaller displacement engine to prove your theory about port size being a bottle neck?

I think rather than run on a smaller engine, I may get one set of the heads ported and re-test.  As mentioned previously I will be building a 390 stroker to test the heads on, but due to the limitations of the block I don't think I can build this engine for the maximum potential power of the unported heads.

[428kidd]

Congrats Jay and thank you for putting forth the effort!

[TomP]

Really impressive and also a surprise the raised exhaust ports are only a bit of extra power. Those are some really good standard exit ports!

[Joey120373]

I am curious what gains might be had with just a simple sanding roll clean up of the ports would gain. As I recall, you gave a chopped section of the first prototype head to someone who did that, just cleaned them up enough to get rid of the casting surface. That helped somewhat didn’t it?

The heads as they are now have been blended just under the valve seat I am assuming?

I fully plan on hitting mine with a bit of sand paper to smooth the ports out, don’t think that can do anything but help.

[jayb]

I'm sure you're right, most of the port is still a rough cast surface.  I think the basic sand roll cleanup netted at least 10 cfm on the intake, not sure about that though.  The valve job did include a cleanup under the seat, to make the inside seat diameter about 90% of the valve diameter, and then blend into the rest of the port.  That's part of the normal valve job at my local shop.