_oldjohnno_
Posted 20 July 2014 - 09:19 PM
To be fair I'm sure they'd run EFI if they were allowed to, and I'm sure they'd go a little quicker with it.
But I'm also sure their heads breathe just a little bit better than a red 186...
I wasn't trying to start an EFI vs Carb religious war, I was just trying to make the point that atomisation in the intake tract isn't always a good thing.
Edited by oldjohnno, 20 July 2014 - 09:21 PM.
_Viper_
Posted 20 July 2014 - 09:54 PM
Huh?? If the TB is in between the entrance to the runner (which is sized for a suitable velocity) and the atmosphere (which has a velocity of zero, but somehow avoids stalling) then I don't see why the engine would care if the TB was a bit big.
Yep I agree with that, which is why I said
If the intake runners are appropriately sized then yes it would be as you mention as they will limit max flow, but looking at the manifold in the second pic the Runners have been made to suit the large throttle bodies.
The second manifold runners from the OP Does not look to be sized for a suitable velocity but merely just to match up with the Throttle bodies
Also agree that for Full load WOT you could pretty much pour the fuel down the throats with a bucket and all would be well, Original poster never said its purely a drag car tho? If it indeed is then I wouldn't see the merit of upgrading to EFI, more components, more complexity, more to go wrong. Carbs do a great job. Most of the fancy tricks of efi are for low speed drivability/power, fuel economy and adapting to conditions. most of those systems are useless/ignored at WOT. Until you start getting into more advanced systems with forced induction like Anti-lag/Launch control, Flat shifting etc (Microtech LT8 isnt exactly advanced tho)
Im curious about about what you mean in regards to a benefit of low atomization on a Low VE engine? Im not trying to start any "wars" here im always learning and open to new ideas (well new to me)
_Bomber Watson_
Posted 20 July 2014 - 10:14 PM
My understanding is vaporised fuel takes up more room in the inlet port than liquid fuel.
So theoretically you could get a bit more air and fuel into the chamber in an asthmatic engine like a Holden six if the fuel wasnt as vaporised.
Im sure OJ will be back and chastise me for my ignorance.
Cheers.
Edited by Bomber Watson, 20 July 2014 - 10:14 PM.
_oldjohnno_
Posted 20 July 2014 - 10:36 PM
Yep I agree with that, which is why I said
The second manifold runners from the OP Does not look to be sized for a suitable velocity but merely just to match up with the Throttle bodies
Im curious about about what you mean in regards to a benefit of low atomization on a Low VE engine? Im not trying to start any "wars" here im always learning and open to new ideas (well new to me)
I'm pretty sure that manifold (one of Brett Bresnans) has three pairs of runners, from memory the divider is a couple of inches downstream from the butterflies. So it mightn't be as oversized as it looks. But anyhow, what you say makes sense.
You're on the right track Bomber, though that's only part of it. When you atomise fuel into an asthmatic port like a 202s, you disrupt the airflow. Remember that the mass of fuel being fed in is somewhere around 8% of the total charge weight so it isn't insignificant. Imagine using a garden hose with a fine spray on a windy day, the water is carried and acellerated by the wind and the energy to do that comes from the wind itself. If you take the nozzle off so it's just a solid stream then the wind doesn't have as much effect on the water, and it follows that the water doesn't have as much effect on the wind either. In other words a solid, low velocity stream doesn't take energy from the airflow to accelerate itself.
Then as Bomber mentioned there is the displacement effect - a gram of vaporised fuel is many many times more bulky than a gram of liquid fuel. On the other hand when fuel vaporises it absorbs a huge amount of heat so it has a cooling effect and raises the density of the intake charge. Whichever is the dominant effect depends mainly on the fuel (and its latent heat of vaporisation) and the breathing capacity of the engine. With methanol it usually works out best to let it vaporise early, but with petrol it isn't so clear cut. From what I can make out it seems any engine that is fundamentally breathing-limited will respond badly to early vaporisation. On the other hand, many modern engines with very good breathing work well with shower-head style nozzles upstream of the runner inlets.
From what I can make out, Holden sixes seem to like the fuel poured in for best power. Of course that's not what you want at part throttle though, and it's also the reason they are such sensitive pains-in-the-arse to jet, temperature wise.
_Viper_
Posted 20 July 2014 - 11:21 PM
Very interesting, and certainly makes sense in that application.
_rb3torana_
Posted 22 July 2014 - 06:55 PM
Option 3 with a 650hp holley or similar. Sheet metal 2" thick with raised carb mounting ( raised carb not shown in picture ) I wonder how distribution would be? Cheers
_oldjohnno_
Posted 23 July 2014 - 07:51 AM
Could it work? Possibly. Is it likely to work perfectly straight off the bat? Almost certainly not. Getting a manifold like that to work well over a range of throttle openings and rpms is very very difficult and time consuming; getting all the subtleties working together will have you pulling your hair out.
I'd be more inclined to use 3 SU type runners - you know that they work and will make power. Then attach a log style plenum of adjustable volume with a pair of 350 Holleys mounted end-to-end on top. I think you'd have a better chance of this working well without a lot of experimental cut-and-shut.
_J.A.W._
Posted 24 July 2014 - 10:16 AM
I bought a rebuilt Q-jet from the 308 shop & bolted it straight onto a Cain 4 barrel 6cyl manifold & it worked great..
It was on a 265 Hemi mill, though..
_J.A.W._
Posted 24 July 2014 - 12:27 PM
Here's how GM did a factory Q-jet on an inline 6 set-up..
http://www.overheadc...om/history.html
Edited by J.A.W., 24 July 2014 - 12:32 PM.
CABIN ENGINE CONTROLS GALORE
Posted 24 July 2014 - 01:11 PM
That is great James,
Never knew they did that, would like to know how well they went.
Here's how GM did a factory Q-jet on an inline 6 set-up.
_Bomber Watson_
Posted 24 July 2014 - 01:26 PM
_J.A.W._
Posted 24 July 2014 - 01:31 PM
Nah Gas-p, no good..
Sure Yanks would accept sporty 6 cylinder 'foreign' cars, but not domestics, even a poor mans Jag - like the Pontiac..
The sporty Chev Corvair - a poor mans Porsche - didn't hack it either & had to be replaced by the Camaro..
& while the E49 Hemi 265 impressed the hell out of the US Mopar engineers, the marketing guys weren't interested,- its gotta be an 8, mate..
FYI the op could try a set of large CV carbs off a motorcycle.. the Honda 1000 V-twin ran two ~50mm jobs..
Edited by J.A.W., 24 July 2014 - 01:34 PM.
_J.A.W._
Posted 24 July 2014 - 04:25 PM
Or for a big-bucks fantasy - try this triple downdraught set-up.. https://www.borlaind...003-series.html
Alternatively, as a budget measure - how 'bout a pair of them big Honda CVs on a ported X2-type manifold?
Edited by J.A.W., 24 July 2014 - 04:26 PM.
_Bomber Watson_
Posted 24 July 2014 - 05:14 PM
_J.A.W._
Posted 24 July 2014 - 05:47 PM
Right..
& DJ, your opinion on the matter would be supported by what empirical/experiential back-up?
Since both downdraught Weber & Q-jet set-ups worked pretty well on the HDT racing 5Ltr V8s, why wouldn't a scaled version work on a 6?
Lamborghini V12s used X 4 triple throat drowndraught carbs, & Ferrari V12s used X 6 DD 2 barrels too - y'know...
_Bomber Watson_
Posted 24 July 2014 - 06:37 PM
A 90 degree v8 cylinder head has the inlet ports facing upward and toward the middle (where the carby is) at roughly a 45 degree angle, as do most 90 degree v engines. I would think the lambrogini and ferrarri engines would have a bit taller heads and less turn in the port, which would mean the inlet ports would face even further upwards, favoring down draught carburettors.
A Holden inlien six has the inlet ports pointing outward roughly level, although i have seen reports of a small performance increase with the runners facing upwards slightly towards the head meaning the holden six inlet ports prefer the inlet charge to be traveling slightly up before it hits the head face, due to the shap of the ports (the port floor and roof both taper up from the head face)
What you are suggesting would involve an extra 90 degree turn in the inlet path on purely the lateral plane compared to a side draught setup, more if you actually run the inlet runners to the head at the correct angle. Not to mention the air/fuel will need to make several extra turns, sharply, to make the ports longitudinally.
Cheers.
_J.A.W._
Posted 24 July 2014 - 06:45 PM
Well, the actual angle of the manifold can be chosen by the op, & note that the HDT 5Ltr race V8s used both downdraught & sidedraught Weber carb set ups..
An injection unit is not sensitive to mount angle like a float bowl, but those big Honda carbs come with angle mount float bowls in-built to suit the V-type engine..
The factory Holden 3.3 injection inlet manifold actually looped 'bout 180` - as did other injected inline 6 applications..
_Bomber Watson_
Posted 24 July 2014 - 06:52 PM
Are you 12?
We are talking about maximum effort engines, not something that starts and runs.
Why do you think v8 supercars run a x ram manifold? The throttlebody, manifold, and inlet port are all more or less straight. the only corner is the short turn to the chamber.
THe factory Holden 3.3 injection manifold was designed to work on the standard engine, and works really well between 1000 and 4000rpm or there abouts. Anything over that its a complete flop. Its designed with long narrow runners to increase the torque spread of the engine, and it loops around because its the most convenient way to package it, as with most other injected six applications.
Im not talking about the angle of the float bowl, i have no idea where you got that from. The reason an injection manifold is less sensitive is because its flowing only air, so you have no worries about fuel dropout.
Though considering most maximum effort efi setups inject the fuel infront of the bellmouth (again, v8 supercars are a good example) the same principles of a carby manifold apply in this case.
Newtons first law of motion: "An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force"
This applies equally as well to air molecules as it does to bricks.
Also the basic laws of fluidynamics dictate that a fluid does not like changing directions.
Seriously mate, wake up ey?
_J.A.W._
Posted 24 July 2014 - 07:04 PM
"Are you 12"? Are you the op? No? Then maybe pipe down, eh fella..
You apparently know SFA about flow dynamics, even by comparison to the HDT ~40 years ago..
Injections systems vary, & some even squirt direct into the combustion chamber, others are a virtual carb, but pressure pump driven not vacuum..
Time for you to do a bit of research to give the inertia between your ears a bit of a tickle up.. eh matey boy..
Edited by J.A.W., 24 July 2014 - 07:04 PM.
_J.A.W._
Posted 24 July 2014 - 07:26 PM
V8 supercar mills ( hardly the nth degree performance wise though, either) do not use "X-ram manifolds" they use tuned length individual intake runners..
& where they do the injecting of the E85?
- Yeah that's right, they use a wet flow runner.. unlike real max performance naturally aspirated injection mills..
Edited by J.A.W., 24 July 2014 - 07:29 PM.
_Waldorf_
Posted 24 July 2014 - 07:32 PM
Popcorn and Drink and off to the Balcony for me..... 
_J.A.W._
Posted 24 July 2014 - 07:45 PM
Wha.. ..indeed.. & those aint 'X-ram manifolds' - these are X-ram manifolds..
http://www.allpar.co.../sonoramic.html
_Bomber Watson_
Posted 24 July 2014 - 07:48 PM
Dead right mate. Cut it off about 2/3rds the way along the runner from the first view and put a throttle body there, what do you have?
Cheers.
_J.A.W._
Posted 24 July 2014 - 07:56 PM
The throttle body is IN the carb.. real hi-performance injection N/A set ups use individual throttles in each runner too..
Individal runner intakes are per se discrete, & are not in fact 'manifolds' at all..
Edited by J.A.W., 24 July 2014 - 07:58 PM.
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