ChargerST wrote: ↑Mon Aug 19, 2019 1:36 am
enigma57 wrote: ↑Sun Aug 18, 2019 9:02 pm
If you elect to do this, I will see if I still have Scott's (DieselGeek's) contact info. He can advise as to engine management computer choice and program an individual cylinder mapping for fuel and ignition for you. As for fitting the prototype DNCF intake to your MOPAR engine, that will involve splitting the intake on a bandsaw, making it 2 individual pieces much as the Aston Martin intake casting. This will allow alignment front to rear with the MOPAR intake runners.
Then you will need to make up some aluminum head plates (adapters/spacers) to go between the intake and heads. These will be much as the plates that allow 383/400 low deck intake to be used on 413/440 raised deck blocks except they will be a bit thicker. Then, with a bit of creative hand fitting, machining and drilling/tapping you will have a 1 of 1 IR type EFI intake for your 400 or 440 engine. Of course, you could do the same thing functionally by utilizing the 'store bought' IDF intake and matching Jenvey IDF throttle bodies. But that wouldn't be as unique as a one off DCNF style intake.
Just an idea,
Harry
Harry,
I had the same idea a few weeks ago: Take this SBC intake manifold, cut it in the center (cylinders 3 and 5 as well as 2 and 4 are not cast together), add thick adapter plates. Should be pretty straight forward as the flange angle is the same between a Mopar 440 and a SBC (55°) and the runner openings have to be enlarged only slightly.
What I'm not sure about is if I should go to the ITB route or add a plenum (basically a large box around the trumpets and have the throttle bodies on the plenum box much like a cross ram)? Tuning should be easier with the plenum style right?
How about resonance charging/pressure waves with ITBs? Does the throttle blade impede with the pressure waves at part throttle? If yes, a plenum intake shouldn't have this problem as I would only add an injector bung to the runners and the trumpets. Disadvantage compared to the ITBs would be a slightly delayed throttle response.
Also the runner opening of this particular manifold is 45mm - a throttle blade would add a further restriction to an already smallish runner (my engine has 505ci).
That's an interesting concept, Charger ST!
Yes, to physically fit it, you must split it in the middle as you say. The big block MOPAR has bore centers farther apart (4.80") than does the small block Chevy (4.40"). And because of that, the paired intake runners at front and rear will need more space between them, as well. So splitting the intake in the center as Aston Martin did mid-'70s (though for different reasons) is the fix for that......
Thick aluminum spacer/adapter plates between intake and head flanges will make up for the taller (and thus wider) MOPAR block. And the unused parts of the Chevy intake can be trimmed off to pare it down to the essentials (runners and flanges for mounting carbs and bolting to heads). You will need to use a divorced MOPAR (or hand built) water manifold and thermostat housing up front. So no need for that portion of the Chevy intake nor for the rear portion having the Chevy distributor mount.
Generally, an IR style intake will give you a bit more midrange torque than a plenum style intake, though each (in theory) should make close to the same power at peak (both TQ and HP) if optimized for the same engine. Personally, I believe an IR intake has a bit more of an advantage than that, though.
Just as with carburettors on an IR intake, you will need to have the ability to individually tune each ITB supplying each intake runner. Only you must do it by mapping out a separate tune for each cylinder (both fuel delivery and ignition) on an engine management computer rather than jetting, tuning, balancing and syncing Weber or Dellorto carbs manually. Which means each exhaust runner (or header primary tube) must be fitted with individual O2 sensors, as well.
Regarding tuned runner length and IR setup versus plenum style intake...... Its a Catch 22 situation, really. Both have their advantages and both have their disadvantages. Once you have determined your ideal CSA for your intake runner (I kept Dan's to the minimum required to achieve an average port velocity of 300 ft./sec. at design redline RPMs (based upon 100% VE at redline), as we were running at EMC and the RPM limit for the pull determined what redline would be). This was to keep port velocity as high as possible throughout his engine's operating range and 'just' reach design redline.
If you have no such rules constraints and are going to base redline on what your engine can pull over an extended period, I was taught to limit redline to whatever would result in 4,000 ft./min. piston speed even when using the best of parts and balancing the bejavvers out of it. You can get away with spinning it higher if you are drag racing and subjecting it to full throttle runs for short periods (12 seconds or less), but I find road racing and flat out land speed record racing more interesting, so have always been conservative when it comes to setting (and building to) a specific redline limit.
Back to tuned runner length...... This is measured from the back of intake valve when resting on its seat up through center of the flow path of headport and intake runner to the point at which you reach end of trumpet if you have an IR intake...... Or to the point where your intake port joins your plenum if you have a plenum type intake. Regarding trumpets, if it has the usual wider bellmouth flare, your calculated tuned runner length with an IR setup will actually be slightly less than the upper rim. I usually figure it to be anything lower than the point at which bellmouth ID increases to 10% wider than ID of trumpet assuming trumpet has similar ID to carb (or ITB) throttle bore size. But that's just a personal rule of thumb. Anyway...... For Dan's engine, I calculated tuned runner length to coincide with the midpoint between peak VE and redline (peak HP) and in Dan's case, peak VE was a couple hundred RPMs more than peak TQ. We couldn't get runner length spot on, as we had EMC rules constraints limiting height of trumpets (AKA velocity stacks), spacers/adapters between carb base and intake, between intake and head, etc. But we were able to come close to our goal of tuning for the stronger 2nd harmonic and did manage to achieve just shy of 116% VE. I doubt if we could have done that with a plenum style intake.
That said...... You will only really take full advantage of tuned runner length with an IR setup when you are at (or very near) WOT, for as you noted...... The throttle blades at part throttle opening do not allow the harmonics to fully work 'for you'. In those instances, the best you can do is to make sure your runner length is such that they do not work 'against you'. The other thing is that at part throttle and lower engine speeds when your engine is running 'off cam' (below the engine speed where your engine is within its designed operating range or powerband)...... You will have noticeable (and visible) standoff atop your trumpets which will remain until engine speed increases to the point where you are running 'on cam' (within your engine's designed operating range or powerband).
Now with a plenum intake where your tuned length runners are fixed length and join the plenum (floor or sidewalls)...... You have a situation where at part throttle there is no issue with partially closed throttle blades interrupting
effective tuned runner length...... But...... Until and unless you are running at or very near the engine speed you have tuned your runner length for...... Again, you are not taking full advantage of tuned length. That's why I say its a Catch 22 (darned if you do and darned if you don't) scenario if your engine is in a road car and you have a wide power band. In those cases, its probably better to calculate tuned length and just make sure your runner length does not work against you.
Personally, I like longer runners tuned for the stronger 2nd harmonic if you can package it underhood because you will also get a little boost as the engine spins up and RPMs coincide with 3rd and 4th harmonics as well. As an example...... Lets say our designed redline is 6,500 RPMs and we pick a hypothetical tuned runner length of 22 inches (position carb throttle blades around 8" from back of intake valve and measure remainder of tuned length through carb and extended trumpet flow path)......
Intake runner length, 22 inches......
2nd harmonic, RPM range from 5,340 RPMs to 6,480 RPMs with peak @ 5,910 RPMs and pulse strength of 10 percent
3rd harmonic, RPM range from 4,012 RPMs to 4,585 RPMs with peak @ 4,299 RPMs and pulse strength of 7 percent
4th harmonic, RPM range from 3,128 RPMs to 3,498 RPMs with peak @ 3,313 RPMs and pulse strength of 4 percent
Note that 2nd harmonic RPM range should 'just' span the distance between peak HP and peak VE, enhancing both. Think of it as the 'jammer' on a roller derby track being boosted by their teammates past the defenders on the other team. And with similar boosts of lesser strength coinciding with 3rd and 4th harmonics ranges as well. What you want to avoid (assuming your engine is well matched to this particular RPM range and redline)...... Is having major events such as the RPM range between peak VE and redline fall within the areas
between each of these harmonic ranges. In that case, tuned length would not coincide with engine speeds the engine was designed for and would work 'against you' rather than 'for you'.
I tried to locate a bar graph that would demonstrate not only the harmonic peaks but the valleys between each of them as well (the valleys are what you want to avoid), but only found the following......
Think of it as if you drop a basketball onto a hard surface from a certain height. Each time it bounces, it rises to a lesser height. Harmonics work the same way, only there is a valley between them equal in strength to roughly the average of the peaks on either side. Make use of the peaks and avoid the valleys and you should be good to go.
Hope this makes sense,
Harry
.. I wasn't aware of Dave Barnets dual quad set up
,I have only ever spoken to Dave (with regards to induction) about six-pack mechanical's as apposed to vacuum ones. I do see Colin quite often and am due to see him in a couple of weeks time actually, but our convertible isn't the same colour as yours I don't believe
, I was more saying we had a convertible like yours 
.. how strange.. I do feel it would be a tad criminal cutting that Chevy DCNF intake Mani in half though but you so kindly gave me that and it was your plan for me to do that.. so I think that is what I am going to do for the 400 engine with the manual gearbox behind it. The whole thing would be a real lovely set up Harry.. thank you for your thoughts Harry and yes I guess I need to talk to Scott to find what management he used... These things are just so exiting
