Hi all,
Just wondering what CFM i could expect form a standard VK 6cyl injection manifold?
Would it be comparable to a 465 holley carb or even a 650 holley?
Cheers,
Barbs
VK injection manifold flow rates?
Started by
_barbermi_
, Oct 07 2009 01:30 PM
23 replies to this topic
#2
FastEHHolden
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Posted 07 October 2009 - 03:57 PM
Can't help with a flow rate...but the VK service manual says it can pulse charge to a pressure of 15 kpa...which is handy.
#3
_oldjohnno_
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Posted 07 October 2009 - 08:12 PM
I don't have the figures handy but I do remember them being quite low (~120cfm??), and that fitting the manifold caused a substantial drop in flow through a standard efi 12 port head.
Having said that, they do work extremely well at filling in the torque curve, you just have to be aware of their limitations. At lowish revs their cylinder filling capabilities belie the low flow numbers. For engines up to roughly 5000-5500rpm and 170-180hp they are ideal but if you need more rpms/hp you'll need to look further.
Having said that, they do work extremely well at filling in the torque curve, you just have to be aware of their limitations. At lowish revs their cylinder filling capabilities belie the low flow numbers. For engines up to roughly 5000-5500rpm and 170-180hp they are ideal but if you need more rpms/hp you'll need to look further.
#4
_barbermi_
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Posted 07 October 2009 - 08:47 PM
I don't have the figures handy but I do remember them being quite low (~120cfm??), and that fitting the manifold caused a substantial drop in flow through a standard efi 12 port head.
Having said that, they do work extremely well at filling in the torque curve, you just have to be aware of their limitations. At lowish revs their cylinder filling capabilities belie the low flow numbers. For engines up to roughly 5000-5500rpm and 170-180hp they are ideal but if you need more rpms/hp you'll need to look further.
Ah bugga The head on my 186 has been flowed to 290HP.
It looks like the fuel injection is out of the question for it then. I would be best goung a 4 barrel carby.
#5
_Bomber Watson_
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#6
rodomo
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#7
_barbermi_
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Posted 08 October 2009 - 05:59 AM
Thanks for the heads up on those parts guys.
I am looking at getting an EFI setup form someone and i was wondering if it has enough flow to suit the 186 i have built.
By the sound of it it is no good at all. How can someone run 400hp on an injected manifold with turbos if they dont flow so good? Or doesnt flow matter if there is a turbo pushing it in there?
If worst comes to worst ill run a holley 600 on it. I have been told i need atleast 500cfm to get the power from the engine.
Cheers.
I am looking at getting an EFI setup form someone and i was wondering if it has enough flow to suit the 186 i have built.
By the sound of it it is no good at all. How can someone run 400hp on an injected manifold with turbos if they dont flow so good? Or doesnt flow matter if there is a turbo pushing it in there?
If worst comes to worst ill run a holley 600 on it. I have been told i need atleast 500cfm to get the power from the engine.
Cheers.
#8
warrenm
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Posted 08 October 2009 - 08:13 AM
Turbo's & blowers are forcing the air in so can overcome some lower flowing ports etc.
Triple 2" SU's will give you what you need.
Triple 2" SU's will give you what you need.
#9
_NZ Toranaman_
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Posted 08 October 2009 - 10:36 AM
Turbos can hide inadequacies of flow.
N/A cars that run fast are usually flowing freely your 186 sounds like a treat but remember its also the little things that can make the difference and I have heard many with a similar setup to mine making it to low 14's in a 1/4 but can't manage to lower it into the 13's which takes a few other factors.
I carefully planned my entire engine from the crank which I threw an angle grinder on to the clutch which is the smallest clutch available for the 202 but I used almost entirely modified stock parts apart from rockers and a stock YT 12-port.
This head managed a 14.3 1/4 on mild street cam and factory EFI with me only fiddling with the airbox as a means of fine tuning
Good luck on your final decision and I want to follow how you get on with much interest.
My choice would be multi-carbs or injection.
N/A cars that run fast are usually flowing freely your 186 sounds like a treat but remember its also the little things that can make the difference and I have heard many with a similar setup to mine making it to low 14's in a 1/4 but can't manage to lower it into the 13's which takes a few other factors.
I carefully planned my entire engine from the crank which I threw an angle grinder on to the clutch which is the smallest clutch available for the 202 but I used almost entirely modified stock parts apart from rockers and a stock YT 12-port.
This head managed a 14.3 1/4 on mild street cam and factory EFI with me only fiddling with the airbox as a means of fine tuning
Good luck on your final decision and I want to follow how you get on with much interest.
My choice would be multi-carbs or injection.
#10
_barbermi_
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Posted 08 October 2009 - 11:22 AM
I will be sure to keep posting on here how it all goes. I will also put photos up as i go with the rebuild. At this stage i only have some before photos of the LJ. It is nearly stripped and ready for paint.
The engine i have has the following:
12 port 2.8lt 186ci
13:1 comp
head flowed at 290hp oversized valves
forged ross pistons
40" overbore
balanced
starfire rods
steel crank
fly cut block
oringed
copper head gasket
1.5 ratio YT roller rockers
HV oil pump
hardened push rods
crack tested
cam designed to rev to 8000rpm with 594 thou lift
This is all i have been told about it over the phone. It was built by my mate 8 or so years ago and he is a bit rusty on some of the details above so it may be incorrect but he has it all written down at home. When he goes back from working away he will clarify it all for me.
Would a holley 600dp be ok for this build?
Ill only be running avgas in it due to the comp ratio.
Barbs
The engine i have has the following:
12 port 2.8lt 186ci
13:1 comp
head flowed at 290hp oversized valves
forged ross pistons
40" overbore
balanced
starfire rods
steel crank
fly cut block
oringed
copper head gasket
1.5 ratio YT roller rockers
HV oil pump
hardened push rods
crack tested
cam designed to rev to 8000rpm with 594 thou lift
This is all i have been told about it over the phone. It was built by my mate 8 or so years ago and he is a bit rusty on some of the details above so it may be incorrect but he has it all written down at home. When he goes back from working away he will clarify it all for me.
Would a holley 600dp be ok for this build?
Ill only be running avgas in it due to the comp ratio.
Barbs
#11
_oldjohnno_
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Posted 08 October 2009 - 05:04 PM
Do you have any photos of the head? I'd love to see what was done; thats exceptionally good flow for a 12 port.
My first preference would be Webers but the cost might be an issue.
Second preference would be 2" SUs.
The 600DP would probably work pretty well too but distribution wouldn't be as good as with triples.
I'm not a fan of the Holley style TBI units; they'd have the same distribution problems as a 4 barrel carb.
My first preference would be Webers but the cost might be an issue.
Second preference would be 2" SUs.
The 600DP would probably work pretty well too but distribution wouldn't be as good as with triples.
I'm not a fan of the Holley style TBI units; they'd have the same distribution problems as a 4 barrel carb.
#12
_barbermi_
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Posted 08 October 2009 - 07:51 PM
I havent got the engine yet. it is in brisbane so ill have to wait a while as im in central SA.
When i do get it ill be fure to start a new thread and post a heap of photos.
When i do get it ill be fure to start a new thread and post a heap of photos.
#13
_Bomber Watson_
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Posted 08 October 2009 - 08:43 PM
Just a couple of thins you should ask your old mate again.
186's never left the factory with a 12 port, so the head is either off a late model 173 or 202.
And a 186 is 3lt not 2.8lt
Also, that cam lift is fairly extreme....I like it
Cheers.
186's never left the factory with a 12 port, so the head is either off a late model 173 or 202.
And a 186 is 3lt not 2.8lt
Also, that cam lift is fairly extreme....I like it
Cheers.
#14
TerrA LX
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Posted 08 October 2009 - 09:21 PM
186 CID at 8000rpm only has a usable flow of about 430CFM right?
unless you are using forced induction or a very special induction system you can not overfill a cylinder.
600 holley should be heaps big enough on a little car.
unless you are using forced induction or a very special induction system you can not overfill a cylinder.
600 holley should be heaps big enough on a little car.
#15
_oldjohnno_
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Posted 09 October 2009 - 06:03 AM
186 CID at 8000rpm only has a usable flow of about 430CFM right?
unless you are using forced induction or a very special induction system you can not overfill a cylinder.
600 holley should be heaps big enough on a little car.
Using calculated flow volumes against Holleys rated figures doesn't work, even though Holley do it themselves.
Holley 4 barrels are rated at 1.5"hg, the 2 barrels at 3"hg. Using either of these figures to choose a carb will result in it being seriously undersized for best performance. Generally this is achieved with a pressure drop of only 0.5" to 0.75"hg, so if you want to calculate the optimimum carb size you first need to convert the numbers to the lower pressure gradient.
#16
_barbermi_
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Posted 09 October 2009 - 06:11 AM
Like i said it was 8 years ago this engine was built so the specs i have given are not entirely correct but just a guide.
When i get all of the details i will post them up for all to see and judge.
At this stage i am more interested in the suitability of the VK inlet manifold for 500-600cfm.
If i modify the inlet manifold to have 2 throttle bodies will this improve the flow or is it simply too limited with the intake runners?
Would i be best making my own inlet manifold?
When i get all of the details i will post them up for all to see and judge.
At this stage i am more interested in the suitability of the VK inlet manifold for 500-600cfm.
If i modify the inlet manifold to have 2 throttle bodies will this improve the flow or is it simply too limited with the intake runners?
Would i be best making my own inlet manifold?
#17
_oldjohnno_
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Posted 09 October 2009 - 06:23 AM
At this stage i am more interested in the suitability of the VK inlet manifold for 500-600cfm.
If i modify the inlet manifold to have 2 throttle bodies will this improve the flow or is it simply too limited with the intake runners?
Would i be best making my own inlet manifold?
The EFI manifold I tested had the plenum split in half (so obviously no restriction due to throttle body) and it still flowed very poorly. The runners are much too long and too small in cross section for an engine like yours, it'd be a disaster HP-wise. Building your own would be fine, or just buy something suitable.
#18
_barbermi_
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Posted 09 October 2009 - 07:56 AM
Cheers mate i will have to ditch te idea of VK injection manifold then.
What would be best do you think a custom EFI manifold ( i like the tuning options of the EFI ) or a carby setup ( I like how simple they are ).
What would be best do you think a custom EFI manifold ( i like the tuning options of the EFI ) or a carby setup ( I like how simple they are ).
#19
_mello92_
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Posted 09 October 2009 - 11:44 AM
These suckers are quite expensive, though, I think this is something like what you would need.
http://www.efihardwa...ottle-Body-Kits
Looking at the site, its probably cheaper to buy everything separate...?
Awesome sounding engine mate!
http://www.efihardwa...ottle-Body-Kits
Looking at the site, its probably cheaper to buy everything separate...?
Awesome sounding engine mate!
#20
_barbermi_
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Posted 09 October 2009 - 12:48 PM
That is a very nice looking setup.
I was thinking i might try making my own custom plenum type inlet manifold?
I have the time and resources (thanks to night shifts) and if all else fails ill have to drop the cash on it and buy something like the link above.
I already have a VK manifod that i may be able to utilise. Ill try cutting the runners off it and reuse the block ends of it.
This will mean i can use the injector ports also.
I wonder if it is possible to open up this part of the manifold any further?
Barbs
I was thinking i might try making my own custom plenum type inlet manifold?
I have the time and resources (thanks to night shifts) and if all else fails ill have to drop the cash on it and buy something like the link above.
I already have a VK manifod that i may be able to utilise. Ill try cutting the runners off it and reuse the block ends of it.
This will mean i can use the injector ports also.
I wonder if it is possible to open up this part of the manifold any further?
Barbs
#21
rodomo
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Posted 09 October 2009 - 03:21 PM
I wonder if it is possible to open up this part of the manifold any further?
I think you'll find once you clean up the ports in the head, there isn't much manifold left to play with.
#22
_NZ Toranaman_
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Posted 09 October 2009 - 04:02 PM
That is a very nice looking setup.
I was thinking i might try making my own custom plenum type inlet manifold?
I have the time and resources (thanks to night shifts) and if all else fails ill have to drop the cash on it and buy something like the link above.
I already have a VK manifod that i may be able to utilise. Ill try cutting the runners off it and reuse the block ends of it.
This will mean i can use the injector ports also.
I wonder if it is possible to open up this part of the manifold any further?
Barbs
Try something like this maybe?
http://www.valiantsp...8jps900865ok5u7
http://www.sixpluspe...e7030fc7103ccff
#23
_barbermi_
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Posted 09 October 2009 - 04:22 PM
Hmmmm now you have me thinking...
What if i used a set of these into a common plenum so i could get away with using the one throttle body?
I am guessing the round flats on the top are for injectors? I would have to machine those out and such but that is fine.
What material are they mae out of? Alloy or steel?
What if i used a set of these into a common plenum so i could get away with using the one throttle body?
I am guessing the round flats on the top are for injectors? I would have to machine those out and such but that is fine.
What material are they mae out of? Alloy or steel?
#24
_sonic_injection_
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Posted 02 November 2009 - 10:28 PM
Hi
I manufacture a IR EFI system for 9 & 12 port engines. I can supply it with short trumpets in a common plenum with any size throttle body on any angle that you wish. My castings are CNC machined. Check out my website
http://sonicinjectio...u/roadtest.html
regards
Brett Bresnan
SONIC Injection
0412 207 547
I manufacture a IR EFI system for 9 & 12 port engines. I can supply it with short trumpets in a common plenum with any size throttle body on any angle that you wish. My castings are CNC machined. Check out my website
http://sonicinjectio...u/roadtest.html
regards
Brett Bresnan
SONIC Injection
0412 207 547
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