FE Power Cylinder Heads on the Dyno, Round 2

[Ghoughton]

Impressive results for sure. But I was wondering the same thing as Ross. Maybe the port cross section is a little small for the application. Resulting in a lower peak rpm than expected. Regardless....still very impressive for just getting stared with the testing.

[machoneman]

Sounds like you need a matching pair of 1450 Dominators.  For the heads to still be as cast, 857 hp on a single 4V is great.  Joe-JDC

I don't think that would help, Joe.  On the 4V intake I was showing 1.6 inches of vacuum at 7000 RPM, so it seemed like a bigger carb would help.  However, on the 8V intake with the two Dominators, the manifold vacuum was ZERO throughout the pull.  Seems like if it needed bigger carbs, I would have seen vacuum with the 8V setup...

Terrific results Jay!

But, my 2 cents: is it possible that the senors used to collect manifold vacuum data could somehow be wrong? Your note on ZERO vacuum throughout the pull seems suspicious. Put another way, have you ever dynoed ANY engine that had zero vacuum at all points? Just askin'!

[jayb]

I have actually, but only with dual carbs and a sheet metal or tunnel ram style intake with a big plenum.  A couple of my big SOHCs and my 530" high riser behaved that way.  I was suspicious of that number too though, so when I saw it I checked to make sure the vacuum line was hooked up to the dyno console, but it was.  So, I believe that data...

[Joe-JDC]

I was just looking at my pictures of your tunnel ram, and I believe that the vacuum port placement is suspect for the zero vacuum reading.  I would like to see it installed in the middle between the carb pads just for grins and a double check.  Where it is located now may be a low pressure area out of the air stream.  Even if it were in the middle of the back, not to the side might give a more true vacuum reading.  Also, is it the same diameter (ID) as the 4V?  Joe-JDC

[frnkeore]

What was the vacuum reading on the first test, with the 8V, 850's?

It also seems like a run with that original, 850 setup might reveal something.

[cjshaker]

I wonder if the exhaust might be working a little too well with that cam at the upper RPM band and over-scavenging the intake charge, pulling some of it out. The SE heads should prove that to be false or a possibility.

Did Joe test the ports up to .900 lift? Any turbulence at all? A little turbulence at those lifts might be more drastic when the airflow starts to reach maximum velocity. I'm not even sure how a flow test could accurately duplicate what happens when you get that high in velocity.

It doesn't seem to be a valve control issue or the numbers would start to get screwy on the top end. Those seem pretty stable, like it's just running out of intake charge. Seems to me, it's just a combo thing. Get the cam to play well with the port, and that 900hp goal is well within reach.

[JERICOGTX]

Very nice Jay.

[JERICOGTX]

Jay, what is the offset of the Intake rockers?

[plovett]

Impressive results for sure. But I was wondering the same thing as Ross. Maybe the port cross section is a little small for the application. Resulting in a lower peak rpm than expected. Regardless....still very impressive for just getting stared with the testing.

CSA is my bet, as well.  I'm no expert, but it's hard for me to imagine the cam being the core problem, causing the power to just stop rising, even if the cam spec's aren't optimal.  The cam looks big enough even if it's particular spec's could be improved upon.  I would think with a suboptimal (but big enough) cam, the hp would keep rising, just not as much as it could with better spec's.  I could be wrong.

850 naturally aspirated hp is no small number.   The engine is over 2 hp per cfm isn't it?

paulie

edit:  looks like right at 2hp per cfm if I got the right numbers.  417 cfm at 0.800" lift?  Just throwing it out there for thought.

[Royce]

I don't think it is related to the intake.. JDC can comment since he flowed them, but IIRC those intake runners flow a lot of air.

The single 4 with an 1150 carb was pulling over 1000 cfm of air according to the airflow meter on the dyno at over 2 inches of vacuum. I think a bigger carb and maybe a different spacer combo, and the single 4 would have easily out powered the tunnel ram. When everything is optimized I think 900 hp can be reached.

My money is on the camshaft as the cork in the bottle currently.

[jayb]

I was just looking at my pictures of your tunnel ram, and I believe that the vacuum port placement is suspect for the zero vacuum reading.  I would like to see it installed in the middle between the carb pads just for grins and a double check.  Where it is located now may be a low pressure area out of the air stream.  Even if it were in the middle of the back, not to the side might give a more true vacuum reading.  Also, is it the same diameter (ID) as the 4V?  Joe-JDC

Joe, fittings on both manifolds were the same diameter, and the vacuum hose was the same diameter.  Frank had a good suggestion, to check the old results, and with the two 850s I was seeing 0.5" of manifold vacuum at peak RPM back in September.  One of the pictures in the original post in this thread shows the vacuum line connected to the back of the manifold, so I know I put it on there.  I suppose it is possible that it fell off or got pulled off sometime during the tuning process and that resulted in the zero vacuum reading, but as I mentioned earlier I have seen zero vacuum readings before, so I think it is probably legitimate.

The engine is apart now, getting ready for the SE heads, so I can't do further testing on this until later this week.  I'll probably start with the 8V intake when I do, so I'll make sure I've got the vacuum line connected and we'll see what the readings are then - Jay

[blykins]

My money is on the camshaft as the cork in the bottle currently.

We will find out soon, I just sent in an order for one.

I'm of the same mind and if I'm wrong, a cam change is quicker/easier/cheaper than having the heads ported. 

The existing camshaft has almost 102° of overlap and not near enough duration split for these cylinder heads.  It may be a situation where the overlap is just pushing power out the exhaust.  There are situations where the cam can be much bigger than what's needed, or even bigger than what the heads can handle, and the engine simply doesn't know what to do with it.  I have ground smaller camshafts for guys in the past who were at wits' end trying to figure out how to go faster and have picked them up a tenth. 

As an engine comparison, a 510" Tunnel Port here with much less duration (270/280 @ .050") and 380cfm heads will peak at 7000-7200.  Jay's heads have 30+ cfm of flow over those.

Took me some time with a lobe catalog to find some lobes that were not spring eaters but had the lobe lift large enough to get us where we wanted to be with a 1.75 rocker ratio, while watching coil bind clearance with Jay's valvetrain. 

If the camshaft doesn't let it zing on up, then I would look to the possibility of needing a little more intake port volume for a large engine.  I'm running into this with the TFS heads right now, as they work really well with a ~170-175cc port and will support big horsepower on a smaller engine, but as I'm looking at some 496-505 ci engine builds, I think the port size will be a limiting factor.  Got a set being ported right now to open up the envelope for a 496ci build going on. 

If nothing else, we will get data, and data is always good, no matter which direction the trend is headed.

[jayb]

I wonder if the exhaust might be working a little too well with that cam at the upper RPM band and over-scavenging the intake charge, pulling some of it out. The SE heads should prove that to be false or a possibility.

Did Joe test the ports up to .900 lift? Any turbulence at all? A little turbulence at those lifts might be more drastic when the airflow starts to reach maximum velocity. I'm not even sure how a flow test could accurately duplicate what happens when you get that high in velocity.

It doesn't seem to be a valve control issue or the numbers would start to get screwy on the top end. Those seem pretty stable, like it's just running out of intake charge. Seems to me, it's just a combo thing. Get the cam to play well with the port, and that 900hp goal is well within reach.

Joe tested one of the early head sections that I had poured but I'm not sure what his results were.  My local shop only tested up to 0.800" lift, but there was no issue there.  Net lift of this cam would be 0.850", so I doubt that there's a turbulence issue since we had good results at 0.800". 

Most of my really strong engines will make 2.1-2.2 HP per cfm of intake flow.  This engine is making 2.06 using the .800" lift flow number.  I think there's more there, with the heads as is, but I guess we'll see...

[jayb]

Jay, what is the offset of the Intake rockers?

The offset is 1.3".

[Dumpling]

Time to try a VCT system?