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Question, why bother with the butterflys at all, just mold the trumpets onto a plenum and attach the std throttle body on the end. Like a really cool version of what AJ6 did and gave up on years ago. Much cheaper and easier to make.
Err....If I did that it wouldn't be an ITB setup then. As for injector location the position matters quite a bit. For daily driving and to help with emissions standards, an injector down-stream of the butterfly squirting directly onto the back of the intake valve is best. For constant high-RPM operation an injector up-stream of the butterfly and far enough away to mix before deflecting off the butterfly onto the walls is best. That is my understanding and I may be only half right or totally wrong.
I am also limited by the weight of metal that I can melt in a back yard foundry before I become a light industrial operation as far as the local council is concerned. Not worth the hassle so I'll be casting at most two bodies per day.
Err....If I did that it wouldn't be an ITB setup then. As for injector location the position matters quite a bit. For daily driving and to help with emissions standards, an injector down-stream of the butterfly squirting directly onto the back of the intake valve is best. For constant high-RPM operation an injector up-stream of the butterfly and far enough away to mix before deflecting off the butterfly onto the walls is best. That is my understanding and I may be only half right or totally wrong.
I am also limited by the weight of metal that I can melt in a back yard foundry before I become a light industrial operation as far as the local council is concerned. Not worth the hassle so I'll be casting at most two bodies per day.
Cheers
Bruce
you are so Kool!
I do good just to remove old rust parts and scrape them down to metal and repaint them..
found this old pic from Jaguar archives, for XJ13 engine,(you may have seen it already).
nice shape to ports, long ram length, injector at trumpet neck, and throttle plate, most important a straight shot to the valve!
some small mentions about your project.
1st it is very pretty, and impressive when you open the hood/bonnet! altho most would not know what thet are looking at.
2nd i'm all about smooth flowing inlet ports, yours would have some disruptions when flowing past the curves and joints, any thing that forces a change in flow direction,would slow velocity, and produce some tumble in ports, and that could effect cylinder filling.
but i do understand, it has to fitt under the factory hood. i'm not sure as a BOLT in kit?
there are some engines that use ITBs(Nissan RB26 turbo), but tests have shown ,custom large plenum with internal trumpets, and a large single TB, actually produce more power and easier to drive smoothly, along with favorable emission results and better MPG.
BUT it just dont look KOOL,or pretty.
i drove a Nissan with the ITBs, and throttle response was like an on/off switch, that along with a triple plate clutch,(NO slip,in or out), was almost dangerous in traffic, trying to get moving and not bump the car in front of you!
anyway like said its just a thought, an old hotrod saying,(if it dont go fast make it look good).
Err....
I am also limited by the weight of metal that I can melt in a back yard foundry before I become a light industrial operation as far as the local council is concerned. Not worth the hassle so I'll be casting at most two bodies per day.
Cheers
Bruce
SO... the local council looks upon you as a Local Artist that works in metal casting?
Keep it Simple! what alloy are you going to be melting/casting...
would you like to have a gander at this PDF on Bell mouth shape....
while reading it I now understand why injectors on the x13 proto-type were placed where they were...
Last edited by Jonathan-W; 12-02-2015 at 03:42 PM.
SO... the local council looks upon you as a Local Artist that works in metal casting?
Keep it Simple! what alloy are you going to be melting/casting...
would you like to have a gander at this PDF on Bell mouth shape....
while reading it I now understand why injectors on the x13 proto-type were placed where they were...
that is the most comprehensive bell mouth essay i'v ever read thanks!
to add, i was 1st made aware of the casting shrinking thing around 1958-59, when i was involved with a SMC chevy (what else), and the guy who made the wood mold made it exactly to size, so it was to small, but the foundry guy made some changes and it turned out great, it more or less was a copy of the famous HILBORN CIS injection system, but it was home made!
it ran but tuning never did it justice, early days!
that is the most comprehensive bell mouth essay i'v ever read thanks!
to add, i was 1st made aware of the casting shrinking thing around 1958-59, when i was involved with a SMC chevy (what else), and the guy who made the wood mold made it exactly to size, so it was to small, but the foundry guy made some changes and it turned out great, it more or less was a copy of the famous HILBORN CIS injection system, but it was home made!
it ran but tuning never did it justice, early days!
I thought you might enjoy that... I surely learned a thing or two...
1958-59...I was not even born then... hahahaha,.....
the below was for the thread author...
after a day or two or digesting that info... I could apply it to the knowledge of a chart on venturi choices for weber carbs...
you see in a carb they want that venturi to make low pressure point where the jet is located since the fuel in the float bowel is a air pressure the lower pressure sucks the fuel out of the jet...
oh, thank G-D we are doing fuel injection... we can use the better flowing bell design because we are injecting fuel and not having it sucked...
so much better for part throttle... and vastly superior for unrestricted flow at wide open throttle
Oh, speaking of tuning, I am sure that you already did all the math for the 12 throttle bodies
but I found this useful calculator I jus put in the bore of 3.54331 and the stroke of 2.75591 with 5500rpm then 6000 rpm and 1 cylinder (since you are doing 12) and got the recommended throttle body size http://www.hipermath.com/math_center...g_calculations
oddly the recommended size for 2 is 51mm and they are 63.5mm
where as aj6eng offers 73mm ones for an improvement with an ecu upgrade gaining a claimed 25 hp...
looks to me as if the bore and stroke and 6 cylinders give the numbers that we have (with the 1.15 ) (the second number on the calc) of 63.8mm so Iam using that for the single cyclinder calc w the 1.15 multiplier
giving 26mm for each throttle body though I am shure you have done all this already....
doing aj6 caclulations... using 8500 rpm and 6 cylinders I get 73mm
switching it to 1 cylinder I get 29.79mm would need the aj6 ecu upgrade to fully realize it...
(sorry slow day at work...)
Last edited by Jonathan-W; 12-04-2015 at 11:32 AM.
The above is a bit of a compromise. These SOHC engines have to have some cosmetic similarities to Jaguar's 1964 quad-cam V12 so aren't necessarily designed for maximum efficiency/power. Throttle bodies are Jenvey and it uses programmable EFI. Base engine is the last-of-line 6-litre although a 6.8 is currently being built for a customer (same stroke as 6-litre but bigger pistons/liners; flat heads with bigger valves).
PS Am currently working on DOHC heads which are based on Jaguar's quad-cam prototype. Am considering heads which bolt straight on to the later SOHC block. I shall use them in future XJ13 recreations but wondered if there would be interest in these heads for other applications? A quad-cam V12 E-Type? Now that would be something - providing the velocity stacks could be short enough to fit under the bonnet :-)
Thanks Neville,
Something similar yes, but not as many frills to keep using as many original parts as possible. If I manage to keep on track and do an XJ13 replica the sky will be the limit though!
If you're doing some new DOHC heads, what valve angle are you looking at? I have some drawn up somewhere here that are at 20deg, but that idea sidetracked into a electro-hydraulic camless/throttleless design so I never finished any carrier details etc. (I get sidetracked a lot when the design bug bites!) I wasn't worried about stack height at the time since the plan was to lightly supercharge that project if it ever happened.
Oh and thanks Jonathan for that info. I had done some initial calcs and am tentatively working to 35mm for now. It might need to come down to 32mm, but depends on how long I can actually make the runners when I do a model fitup.
Thanks Neville,
Something similar yes, but not as many frills to keep using as many original parts as possible. If I manage to keep on track and do an XJ13 replica the sky will be the limit though!
If you're doing some new DOHC heads, what valve angle are you looking at? I have some drawn up somewhere here that are at 20deg, but that idea sidetracked into a electro-hydraulic camless/throttleless design so I never finished any carrier details etc. (I get sidetracked a lot when the design bug bites!) I wasn't worried about stack height at the time since the plan was to lightly supercharge that project if it ever happened.
Oh and thanks Jonathan for that info. I had done some initial calcs and am tentatively working to 35mm for now. It might need to come down to 32mm, but depends on how long I can actually make the runners when I do a model fitup.
Cheers
Bruce
Glad to be of what little help I can...
the smaller is better for low end and drivability
the larger is better for top end breathing and HP
I over did it on my sprite when I went to a DCOE 45 with a large choke
it would have the wonderful effect of when I snapped open the throttle of making a big gasping sound then a very large fist size cloud of spit back and a sudden low pressure sucking everything back in and spinning the engine to rpms that my machinist refused to come out and witness......
(you know rednecks famous last words... "hey watch this!")
kind of funny a 4 cylinder at 10,000 rpms sounds scary 333 1/3 hz
a v12 at idle 750 rpm is 75 hz and at 6000 rpm is 600 hz and at 6500 is 650 hz 7200rpm is 720 hz..
ah mufflers keep me from getting tickets....
at 3000 rpm my v12 should sound as scary as my old sprite 1275...
on the trumpet bells did you ever consider spinning them?
Yep, I might spin them depending on final clearances and bends. If the bodies need to be bendy like the first ones I drew then I may as well just make it past of the casting. Easier to include mounting feature for different filter types too.
As for a best engine sound in the world? I had my exhausts uncorked at the downpipes while I was cutting out the cats after a FPR failure. I decided "What the hell!" and fired her up. An unmuffled V12 at 6500 is unforgettable. Just ask anyone that was living within a few miles of where I was at the time
Yep, I might spin them depending on final clearances and bends. If the bodies need to be bendy like the first ones I drew then I may as well just make it past of the casting. Easier to include mounting feature for different filter types too.
As for a best engine sound in the world? I had my exhausts uncorked at the downpipes while I was cutting out the cats after a FPR failure. I decided "What the hell!" and fired her up. An unmuffled V12 at 6500 is unforgettable. Just ask anyone that was living within a few miles of where I was at the time
yes the Cop(bobbie, law-inforacement officer ) that gave me my ticket for pulling my Austin to 9k in first told me he had to drive over a mile to find me...
" you know that's LOUD when your getting on it" he said ... because when I saw him I shifted at 1.5k each gear... pulling off from the light...
Last edited by Jonathan-W; 12-11-2015 at 10:57 AM.
PS Am currently working on DOHC heads which are based on Jaguar's quad-cam prototype. Am considering heads which bolt straight on to the later SOHC block. I shall use them in future XJ13 recreations but wondered if there would be interest in these heads for other applications? A quad-cam V12 E-Type? Now that would be something - providing the velocity stacks could be short enough to fit under the bonnet :-)
@Neville - I would certainly be interested if these could be made available for the original block. As I mentioned earlier before in this thread, anything that is a bolt on upgrade would be fantastic.
Yep, I might spin them depending on final clearances and bends. If the bodies need to be bendy like the first ones I drew then I may as well just make it past of the casting. Easier to include mounting feature for different filter types too.
As for a best engine sound in the world? I had my exhausts uncorked at the downpipes while I was cutting out the cats after a FPR failure. I decided "What the hell!" and fired her up. An unmuffled V12 at 6500 is unforgettable. Just ask anyone that was living within a few miles of where I was at the time .
.
i agree about a V12 with loud exhaust, mine ALL twelve cylinders out of ONE outlet, 5" diameter.
multiple outlet exhausts breakup a nice smooth sounding flow!
Yep, I might spin them depending on final clearances and bends. If the bodies need to be bendy like the first ones I drew then I may as well just make it past of the casting. Easier to include mounting feature for different filter types too.
As for a best engine sound in the world? I had my exhausts uncorked at the downpipes while I was cutting out the cats after a FPR failure. I decided "What the hell!" and fired her up. An unmuffled V12 at 6500 is unforgettable. Just ask anyone that was living within a few miles of where I was at the time
11-25-2015, 03:58 AM
As for injector location the position matters quite a bit. For daily driving and to help with emissions standards, an injector down-stream of the butterfly squirting directly onto the back of the intake valve is best. For constant high-RPM operation an injector up-stream of the butterfly and far enough away to mix before deflecting off the butterfly onto the walls is best. That is my understanding and I may be only half right or totally wrong. 
Would love to hear it... do you think you could record it for us and post it?