OK, so I have too much time on my hands. My wife complains that I'm obsessed with this 'stupid Ford engine' stuff. Maybe I am, but at least it's more educational/constructive than her online gaming... ;-p
Anyways, I've taken the liberty of modelling Tim Meyer's 400 build up the best I could in DynoSim (big brother to Desktop Dyno aka DD2K). I know these models are to be taken with a grain of salt (to say the least,) but it may give us an idea of what we'll see and (what-the-h**k) it's fun!
Assumptions I've made:
- 9.7 static compression
- Comp Cams XE268 (based on numbers from Tim's cam page)
- stock (and ported) Aussie head flow numbers from http://web.archive.org/web/200208140...s/351heads.htm
- engine dyno'd with 600 cfm 4-bbl carb, small-tube headers and open exhaust.
Consider the Edelbrock to be a 'dual plane standard flow' (DP-STD), the Weiand as a 'dual-plane high-flow' (DP-HI), and the Holley to be a 'single-plane standard flow' (SP-STD). I know these may not match each of these intakes exactly, but those are the options available in Dynosim and it should give us an idea of the variations we might see.
so my guess is that it'll dyno over 450 ft-lbs from 2000-4000 rpm and ~350 hp @ 4500 rpm.
This seems to indicate that the head flow will be the limiting factor in this engine's potential in the upper rpm range. Wondering why Tim chose not to port? Granted, a truck motor might not run over 4000 rpm all the time, but porting sure makes a big difference up there, if we're to believe the models...
The cam we used was the custom Comp Cam that is listed on the "cam page"
I have not gone into details on the heads yet, but, we did install 2.190" intake and 1.760" exhaust. Did the bowl work to blend seat area down.
As you have stated, port work would help in higher RPM's (so will the bigger valves) and being a truck engine, I wanted to see torque numbers.
I like to see better throttle responce, basically the items that would make a nice 4X4 engine.
Hopefully what we will learn how the different intakes will respond. Also I wanted to tackle the "low oil pressure" problem. And see how the Hypereuctic pistons work out.
I need to sell this engine when it's done, so I didn't want it to radical. I'd like the next project to be the 400 with the Eagle 4.250" stroke crankshaft.
Right on, Tim. I did take the cam numbers from that custom cam on your page. I assumed it was modelled after their XE268, so labelled it that way. Although the head flow data was for the stock valve sizes, I also did take into account that you had put in larger valves. Can't wait to see if these models are anywhere close to reality... :-)
To get the GIF's, I just use the printscrn key (win XP) to snap screen
then paste into Adobe ImageReady and 'save optimized' as a GIF.
I used 9.7 as the CR as that what Tim said he had.
As for the cam, I used the numbers from the custom comp cams in Tim's file.
Same duration as yours, but max lift is 524/530. I must admit that I don't really know what these cam numbers mean. I just plugged in the ones I have...
Large tube headers vs. small don't make too much difference on this motor, but muffler certainly do. I left 'em off 'cuz I figured they wouldn't be used on the engine dyno, but maybe that's not a valid assumption?
Curious to know how your Aussie head flow data differs from that in the link I posted. Flow data I've seen for these heads tends to vary all over the place. I don't suppose Tim bench-flowed his heads before assembly? That would be very instructive...
No Tim didn't flow the heads. Kicking myself right now. I was planning to flow the heads and intakes. Beginning of Dec. started very busy and I didn't get the time. Unfortunatly I still have to try and make money instead of playing with engine projects. I have a 351C we are building for a dirt track race car. We are building them both side by side. So unfortunatly I am not giving the time I would have liked to, to the 400 project.
Maybe next time.
I did email Dan the exact specs for the cam we used.
After spending some time with some Cleveland experts, I am going to shoot for a header tube size a little bigger than I would normally want to pick. The Cleveland heads are exhaust restricted and any help would be worth it, but I want to maintain the same "RV" header tube length.
Dynosim allows one to enter head flow numbers measured at a certain valve size and run them at any other valve size. When I put in the Fletcher/Powerheads numbers for unported Aussie heads with 2.19/1.76 valves, I get almost exactly the same curves as the Waldens 2.07/1.65 head flow numbers running the bigger valves. That is re-assuring!
Your screen shot shows the CompCams Ford 32-207 (comp cams 265deh)
Did you edit this cam file to reflect Tim's timings or is that not quite the right screen shot? Are the cam specs Tim emailed you different from those on his web site for the 'Comp Cams custom' grind?
I think I see why my curves differ from Dan's. I think there may be a typo in the specs for the 'Comp Cam-Custom' grind (#FC5433/5216H110) in the web page at http://www.tmeyerinc.com/400hydcams.htm.
I notice the Advertized duration for the XE256 and XE262 is longer than the intake, which we all know is preferable for these engines. Yet the custom grind, which I understand to be based on the XE268, has advertized intake AND exhaust duration of 268. If I use an advertized exhaust duration of 278 (instead of 268), my curves look more like Dan's, with peak HP just over 5000 rpm.
Can either of you confirm that the advertized exhaust duration on the web page is incorrect? If so, our models pretty much converge, which is encouraging!
Yes, I did edit the 32-207-3 file and manually entered Tim's lift and duration @0.050.
The Hot Rod mag article give the grind # FC5433-5216 H110. That is the same grind # as Tim's cam. The ADV duration is listed as 268/268 even though the duration @ 0.050 is 224/230. The difference in lift may be due to rocker ratio. 1.73 vs 1.7.
Tim's cam chart also shows the intake center at 106 degrees. This means that the cam is advanced 4 degrees. My simulation was at zero degrees, this gives an IVC of 42 degrees per the cam spec. If the intake lobe center is at 106 degrees, then the IVC will be 38 degrees.