545" High Riser Build

[Joe-jdc]

Looking good, Jay!  One thing I found with your radius on other manifolds was that the air wants to cling to the wall where it does not have the radius.  Kinda like a water fall.  I found if I had any break in the turn, then airflow increased.  What I am trying to say is that if you could complete the radius all the way around the opening, I believe you will have a better transition into the runner, and would not have any puddling in the plenum bottom.  I know the picture of the TFS does not have a complete radius around each runner, but I still have seen that kind of ledge decrease airflow over a complete radius, even a small lip would be better than nothing.  JMO, flow tested and verified on Hogan, Comp Cams Plenum box, Sheet metal intakes, and aluminum spacers.  Joe-JDC.

[jayb]

Thanks for the heads-up on that Joe, I will work a little more on that lower radius.

[Mario428]

Keep wanting to throw my 2 cents in and had a thought. LOL



Runner with a curve, flattens the angle where the port goes into the plenum and gives some separation maintaining the same length.
Biggest problem is it requires a left and right hand runner section

I would also make the forming dies from UHMW polyethylene, very easy to mahine and more than strong enough if you use a fairly large section

http://www.mcmaster.com/#uhmw-polyethylene-sheets/=forv6h

They sell reasonably price ballnose end mill too for the corners, only need hi speed steel for alum & UHMW

5/8 part #  3046A44   on   http://www.mcmaster.com/#end-mills/=forw55

[jayb]

Another interesting idea, but I've wanted to stay away from curved runners.  As I understand it, it has been fairly conclusively shown that curves in the runners cost horsepower via airflow reduction and fuel distribution issues.  All the modern tunnel ram style intakes, like sheet metal manifolds, use a straight runner rather than a curved runner.

On my SOHC sheet metal intake, to get the runner length I want I plan to machine a filler piece for the plenum that puts a curve in the runner inside the plenum itself.  It will be required because the port on the SOHC is so short that the runner length going up to the plenum puts the tuning of the runners around 8800 RPM, and I'm not going to be spinning the engine that high.  The filler piece that curves the runners in the plenum will allow me to stack plates up on top of it, to extend the runner lengths for tuning purposes.  But under the plenum the runner will still be straight, and that's where the fuel will be injected.  So that design is kind of a compromise, because the air will have to turn in the plenum, but the fuel will be in a straight line airstream.

Thanks anyway for the thought, Mario, and the information on the material.  If I ever needed to make a curved piece that would be a good way to go.

[machoneman]

It's my understanding too that straight runners are the hot ticket for drag racing engines that use carbs at the very top of the common plenum and, as stated, curves in runners cost hp due to airflow reduction and fuel distribution issues.

But, is this really true (fuel distribution at least) if one is running a port-injected EFI system?

I'm just thinking of the many heavily-folded curves in an late 80's-1994 OEM 5.0 Windsor engine with mass air. In essence, the intake only handles air and of course the fuel is added via an injector just before the head runner starts. I guess my point is if your not running carbs does using a curved runner (with EFI bungs/injectors down low on the intake runners) really hurt performance? Maybe that fella Barry R is setting you up with would know...just like I'm sure the rest of us here would too!       

Another interesting idea, but I've wanted to stay away from curved runners.  As I understand it, it has been fairly conclusively shown that curves in the runners cost horsepower via airflow reduction and fuel distribution issues.  All the modern tunnel ram style intakes, like sheet metal manifolds, use a straight runner rather than a curved runner.

On my SOHC sheet metal intake, to get the runner length I want I plan to machine a filler piece for the plenum that puts a curve in the runner inside the plenum itself.  It will be required because the port on the SOHC is so short that the runner length going up to the plenum puts the tuning of the runners around 8800 RPM, and I'm not going to be spinning the engine that high.  The filler piece that curves the runners in the plenum will allow me to stack plates up on top of it, to extend the runner lengths for tuning purposes.  But under the plenum the runner will still be straight, and that's where the fuel will be injected.  So that design is kind of a compromise, because the air will have to turn in the plenum, but the fuel will be in a straight line airstream.

Thanks anyway for the thought, Mario, and the information on the material.  If I ever needed to make a curved piece that would be a good way to go.

[jayb]

I think it is probably largely correct that the fuel distribution would not be an issue if you injected at the port.  However, if you have ever looked inside an injected sheet metal intake, you will see it gets wet with fuel in there.  So, despite the injector location, fuel moves around in the intake, and will therefore be subject to some extent to the airflow issues inside.

Also, with this intake I will be positioning the injectors as high up on the runner as possible.  The advantage that carbs have over injectors in these applications is that the fuel acts to cool the air/fuel charge  as it leaves the carb and travels down the runner to the port.  When you inject right at the port, there is less time for this cooling to take place, so a port injected engine where the injector is very close to the port will be down on peak power a little as compared to the carbs.  On the other hand, if you position the injectors up high on the runner, you get most of this effect back, albeit with less low speed control.  As I understand it, Formula 1 engines put the injectors up at the top of the plenum, where the carb would normally be, in order to maximize this effect.

[machoneman]

The cooling effect is present for sure. Interesting that you've decided to mount the injectors high up, ala' a carb's exit of an air & fuel mix, a nice move for sure. Then straight runners for sure.

Forgot about the F-1 engineers doing the same to those high winding engines.     

[cdmbill2]

Fuel distribution IS an issue with direct port injection, just as it is with carbs, because of reversion, resonance, and boundary layer effects on the fuel in suspension in the airflow. Below is datalog of the same 588" 385 motor I mentioned in an earlier post. The datalog is from an engine dyno pull where we used eight AFR sensors mounted in the primary tubes of the dyno headers.

The tested RPM range is from 4500 - 7500 although the graph covers roughly 3500 to almost 8000. Look at Cylinder #2, the Red line in the bottom graph. During a WOT pull it goes as low as 10.7:1 AFR, and then 2 seconds later it's running at 13.5:1. The mid line is 12.5 AFR.

Cylinder numbering:
Top Graph: (Yellow=1, Blue=3, Purple=5, Green=7)
Bottom Graph: (Red=2, White=4, Blue=6, Yellow=8)

You'll see the traces for each cylinder move around quite a bit but variation narrows at around 5500 rpm through 7500 which is the target WOT operating RPM.

You can see a video of the setup here: http://www.bangshift.com/blog/Dyno-Video-A-598ci-1014hp-Ford-Big-Block.html

[jayb]

Bill, that is great data!  This must be the 'geek' setup at work?  Where in the headers did you put the O2 sensors?  I need to get bungs welded into my headers so Scott can put that setup on my high riser, but I'm not sure where they should be positioned.

Edit:  Never mind, I just watched the video and got a look.

[machoneman]

Great detail, Bill. I guess one could expect some variations in the a/f ratio in any intake at any rpm but it's amazing just how much it bounces from one reading to another, let alone cylinder-to-cylinder variation. Helps explain technically too why those who tried to run a T-ram on the street (I didn't but had folks ask me to look at their setup) had a devil of a time with lean/rich running and poor low engine speed performance.

[cammerfe]

I think it is probably largely correct that the fuel distribution would not be an issue if you injected at the port.  However, if you have ever looked inside an injected sheet metal intake, you will see it gets wet with fuel in there.  So, despite the injector location, fuel moves around in the intake, and will therefore be subject to some extent to the airflow issues inside.

Also, with this intake I will be positioning the injectors as high up on the runner as possible.  The advantage that carbs have over injectors in these applications is that the fuel acts to cool the air/fuel charge  as it leaves the carb and travels down the runner to the port.  When you inject right at the port, there is less time for this cooling to take place, so a port injected engine where the injector is very close to the port will be down on peak power a little as compared to the carbs.  On the other hand, if you position the injectors up high on the runner, you get most of this effect back, albeit with less low speed control.  As I understand it, Formula 1 engines put the injectors up at the top of the plenum, where the carb would normally be, in order to maximize this effect.

Jay, can you say E85? Low injector AND superior cooling! (Just a thought)

KS

[jayb]

Availability of E85 is the problem.  Used to be fairly common in my area, but it has mostly disappeared.  Beyond that, there is no guarantee that it will be available on a road trip (for example, on Drag Week).

I have thought about running methanol, with a dual fuel system that uses methanol at the track and pump gas on the street.  There are some cool ways you can do that with a cleverly applied EFI system, but so far I haven't ventured down that path.

[cdmbill]

Jay, you asked about runner length and other dimensions. The length from the plenum wall to the back of the valve is approx. 11.5". Plenum volume is approx. 625 cu/in. after porting without including the small area under the TB's in the top plate.

As you saw, I'm working with a cast manifold which is good from a dollars perspective but is somewhat one size fits all. IIRC It was originally developed for 500 Cu/in. NHRA Pro Stock way back in the day, but like the heads, has gone through some modest changes along the way.

PipeMax says they could be a bit longer for the displacement and RPM, but not much, and with the porting and the match to the cylinder heads, the taper is real close and I was pleased with the results given the compressed time frame and budget constraints I'd placed on the build.

Obviously you know that da Geek was involved, thank goodness, and I benefitted from their EMC experience. I welded the bungs into Dougan's dyno headers 12" from the port with the same orientation as much as possible. (Nice guys to let me hack on their dyno headers) I've replicated the bungs now on the in car headers, but the locations are not quite as uniform as I have to deal with installing/removing the eight sensors from the tight confines of a fully chassis dyno ready car.

Machoneman: I was frankly surprised that idle quality and drivability were as good as they are with the T-Ram and dual 2180 CFM TB's. In part I think it was because our baseline tune had a lot of drivabilty work done on the previous version of the engine which was only 6 cu/in smaller but had a single big TB on a tall single plane manifold and a slightly smaller cam.

Secondly, we went from an in neutral idle RPM of 1200 up to 1300 and the car has a pretty high stall converter in it at the moment which masks a lot of low speed stuff. BTW the cam is 282/294/113 with .830 lift. I am likely used to some less than ideal NVH in my supposed street car, but that's road we've gone down trying to be competitive at Drag Week with big heavy cars. That said doing this with EFI is way easier on gas and with far better manners than an equivalent dual four barrel carb set-up.

One last note, it was almost impossible to watch eight AFR readouts during a pull. We tuned off the two sensors in the collectors for the most part, but the addition of the eight AFR's in the primaries along with eight EGT's really helped fill in the gaps.

[machoneman]

Good to know. But an .800+ lift "street" cam? Wow, I'd be chicken to try that for sure. I can only guess 50% nitro would be next...LOL!

[jayb]

One last note, it was almost impossible to watch eight AFR readouts during a pull. We tuned off the two sensors in the collectors for the most part, but the addition of the eight AFR's in the primaries along with eight EGT's really helped fill in the gaps.

Having all eight AFR readouts seems like it would point towards individual injector tuning as the next logical step in really dialing in the engine.  Unfortunately the ems-pro doesn't have the capability, but the FAST and BigStuff3 setups have it, because they can go to full sequential.  I was actually contemplating a switch to a BigStuff3 setup at one point, because I wanted to maintain the full sequential capability of the FAST setup but still be able to run the Ford trigger wheel.  The Geek, and the price, talked me out of it.  Seeing your data, though, I can see where there is power to be had with individual injector tuning.  Besides that, it would be loads of fun to vary one injector on the dyno and see what changed.  Hmmmm....