Hey there im thinking of making a custom EFI manifold for my 202, am trying to cut the cost of buying an expensive off the shelf item (approx $3000)..
Was thinking of using a weber manifold and either making a plenum on the end with say 2 standard vk throttle bodies????? Or trying to find 6 smaller throttle bodies (gemani, barina,camira,) not sure of sizes though?? and adapting them to fit like the ones you can buy.. need help guys:)
custom efi 202 manifold
Started by
_EFI-GTR_
, Feb 14 2010 11:12 AM
25 replies to this topic
#2
_oldjohnno_
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Posted 14 February 2010 - 02:45 PM
A Weber manifold with a fabricated plenum box bolted or welded on sounds good. You'll have to weld in some spuds for the injectors obviously.. The TB size isn't all that critical so long as it isn't too small, though if it's way too big it becomes hard to drive smoothly at small throttle openings. Two VK TBs would be very close I'd guess. Have you worked out the runner lengths yet? It'll probably work out to around 8 - 10".. If you want you could post or PM the cam specs and I'll work out the lengths etc..
#3
_oldjohnno_
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Posted 14 February 2010 - 03:13 PM
Dunno if anyone's interested but I just stuck a VK EFI manifold on a mild (about 150cfm) 12 port head that I'm playing with at the moment. Putting on the manifold dropped the flow nearly 20cfm; with a really well-ported head the loss would be even more.
#4
_coupe202_
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Posted 14 February 2010 - 03:20 PM
Just finished building a custom efi manifold for holden six, will know how it works once engine is dynoed.
#5
Stinga
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Posted 14 February 2010 - 03:50 PM
i was googling something holden 6 related the other day and saw one made with a triple su manifold and a plenum box bolted to that, looked good. i will see if i can find it again
#6
Heath
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Posted 14 February 2010 - 05:03 PM
Is that for a 9-port or a 12-port setup? I'm interested in having a geeze if you have any photos, and yeah would love some results once it's been dyno'd. Keep us posted TonyJust finished building a custom efi manifold for holden six, will know how it works once engine is dynoed.
#7
_coupe202_
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Posted 14 February 2010 - 05:27 PM
The manifold is to suit a 12 port head.
#8
Stinga
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Posted 14 February 2010 - 06:15 PM
actually, might not even be an su manifold, but still worth a look
http://autospeed.com...71/article.html
http://autospeed.com...71/article.html
#9
_oldjohnno_
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Posted 14 February 2010 - 07:51 PM
actually, might not even be an su manifold, but still worth a look
http://autospeed.com...71/article.html
I sincerely don't mean to sound critical of the builder of that HR - the workmanship and finish looks to be very good - but it seems to be another example of an engine that would have turned out much better with a bit of planning. Another 50% on the hp output would have been easy to achieve without making it the slightest bit cranky. It combines the disadvantages of both the 9 and 12 port heads.
To get the full performance benefits of a true IR manifold, whether carbureted or injected, you need to use a 12 port head (and not just a 9 port with dividers). As well, the manifold must be dimensioned carefully to match the cam and the desired torque peak, otherwise you may as well just jam a two barrel on it.
#10
_EFI-GTR_
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Posted 14 February 2010 - 09:19 PM
hey all, yeah it is a highly modified stage 3 yella terra head.. Here are the cam specs oldjohnno, it is a solid wade cam.........it has 11.1 comp rev range from 3500- 7000
lobe separation:105
valve lift :.339
inlet open .48 close .87 ex open.78 closes .57
duration 262@ .50
it has been on the dyno twice in the last few weeks and can't go over 5500rpm and made 130kw..
Be interested to hear your progress also coupe 202
lobe separation:105
valve lift :.339
inlet open .48 close .87 ex open.78 closes .57
duration 262@ .50
it has been on the dyno twice in the last few weeks and can't go over 5500rpm and made 130kw..
Be interested to hear your progress also coupe 202
#11
_evil UC hatch_
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Posted 14 February 2010 - 09:40 PM
if your still looking for 6 smaller throttle boddies the nissan skyline GTR had a 6 throttle body set up, on the RB26 twin turbo motor, although I dont know how easy a set of them would be to get. could be worth a phone call to a jap import wrecker
#12
_Bomber Watson_
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Posted 14 February 2010 - 09:44 PM
Its pretty common knowlege that one big throttle body into a plenum is superior to individual throttle bodies anyway, so why bother???
Cheers.
Cheers.
#13
Peter UC
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Posted 14 February 2010 - 09:55 PM
Is that the reason why all race engines use ITBs
#14
GTR600
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Posted 14 February 2010 - 10:10 PM
We got a vk efi running today though a delco vn computor,
Was sitting on the floor but run ever so smooth.
We were looking at a four barrel manifold from aussie speed, i think thats what there called to suit the 12 port with a large thottle body on top.
they come with thicker locating points for injection and are flow tested with the yellow terra 12 port allow head which is what i wanted to use.
The other option was to chop down the vk unit and weld on a pre fabbed plemium chamber,that being there biggest restriction
Was sitting on the floor but run ever so smooth.
We were looking at a four barrel manifold from aussie speed, i think thats what there called to suit the 12 port with a large thottle body on top.
they come with thicker locating points for injection and are flow tested with the yellow terra 12 port allow head which is what i wanted to use.
The other option was to chop down the vk unit and weld on a pre fabbed plemium chamber,that being there biggest restriction
#15
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Posted 15 February 2010 - 04:35 PM
Thats what it has got at the moment GTR600, A custom twin throttle body plenum on standard vk manifold runners.. Wont rev over 5500.. no matter what i do.. Apparently would be great for a turbo set up........ I am now thinking of a weber manifold with smaller EFI throttle bodies off a small car like a barina or something,,,, any one know of the sizes of something like this????? What do think would be the advantage or disadvantage of a plenum.. bomber watson?
Edited by EFI-GTR, 15 February 2010 - 04:38 PM.
#16
_oldjohnno_
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Posted 15 February 2010 - 05:49 PM
My understanding is that a plenum type manifold will give a slightly broader torque curve and will help fill in some of the holes usually found lower in the curves of an isolated runner setup. There are formulas for the plenum volume but in practice it doesn't seem to be anywhere near as critical as the other numbers. At any rate I'd be sticking with a plenum for simplicity's sake if nothing else.. it's got to be easier to set up one or two TBs rather than six.
These are the sort of sizes to shoot for - assuming a 6500rpm power peak:
Runner length 13.78" (this includes the 3.7" port length of a 12 port intake!!)
Runner entry CSA 1.95 sq.in
Plenum volume 160 to 200 cu.in
The runner entries need to be radiused, and obviously you'll want to position the TBs so as to avoid disrupting the flow into the runners. Forgot to look at TB sizing but can do if you want.
I guess you already have the exhaust done but I'll chuck in the PipeMax recommendations just for interest (tri y style): Combined pri/sec length 32", 1.59" pri, 1.7" sec, 3" x 2" tapered collector. Collector length for best torque spread 17.9", for best peak hp 9".
These are the sort of sizes to shoot for - assuming a 6500rpm power peak:
Runner length 13.78" (this includes the 3.7" port length of a 12 port intake!!)
Runner entry CSA 1.95 sq.in
Plenum volume 160 to 200 cu.in
The runner entries need to be radiused, and obviously you'll want to position the TBs so as to avoid disrupting the flow into the runners. Forgot to look at TB sizing but can do if you want.
I guess you already have the exhaust done but I'll chuck in the PipeMax recommendations just for interest (tri y style): Combined pri/sec length 32", 1.59" pri, 1.7" sec, 3" x 2" tapered collector. Collector length for best torque spread 17.9", for best peak hp 9".
#17
_Bomber Watson_
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Posted 15 February 2010 - 05:57 PM
What oldjohnno said, but i did lead everyone astray slightly...
For some reason i had turbo in my mind not NA. Note everyone takes the six throttle body setup off the R34's and puts a single tb with a big plenum on....
My bad, gotta stop drinking
IF DONE PROPERLY, i think a Plenum would work better in most cases.
You do know you can just buy webber style throttle bodies that bolt strait to a webber manifold and have injector bosses etc already built in.....would be a good way to go for a masimum effort NA engine...
Cheers.
For some reason i had turbo in my mind not NA. Note everyone takes the six throttle body setup off the R34's and puts a single tb with a big plenum on....
My bad, gotta stop drinking
IF DONE PROPERLY, i think a Plenum would work better in most cases.
You do know you can just buy webber style throttle bodies that bolt strait to a webber manifold and have injector bosses etc already built in.....would be a good way to go for a masimum effort NA engine...
Cheers.
#18
Peter UC
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Posted 15 February 2010 - 06:44 PM
It's interesting to note that in the turbo F1 days BMW had 5 throttle bodies on their 4 cylinder engine. One for each cylinder and one in front of the turbo. Apparently the reason was for better throttle response and for better low speed running (ie through the pits etc). Of course that was a full race engine with 60+psi shoved down its throat so it doesn't really mean a lot here but interesting nevertheless.
#19
_EFI-GTR_
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Posted 15 February 2010 - 07:19 PM
thats been a big help guys thanks:) if you have any info on tb sizes oldjohnno that would be unreal!! and i have seen those tb that bolt on to the webber manifolds.. seem quite expensive though.. do you think a plenum and say 2 vk 75mm tb's will work??
Edited by EFI-GTR, 15 February 2010 - 07:19 PM.
#20
_Bomber Watson_
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Posted 15 February 2010 - 09:39 PM
If your custom fabbing everything why not look for a single bigger one?? Less wiring less cables etc.
Gotta be heaps of stuff big enough that you can get cheaply, standard tb off a vn 308 perhaps?? Or even a LS1 job? Toyota or nissan v8? Even a 3.8 ecotec one might be big enough....Just do some sums
Just throwing ideas around....
Gotta be heaps of stuff big enough that you can get cheaply, standard tb off a vn 308 perhaps?? Or even a LS1 job? Toyota or nissan v8? Even a 3.8 ecotec one might be big enough....Just do some sums
Just throwing ideas around....
#21
GTR600
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Posted 15 February 2010 - 10:19 PM
Dont shoot me down just a few thoughts.
I think the old standard 5L runs a 70 or 75mm tb one would think that would be enough for a six and less work than two as the bomber mentioned.
Does your computor system have a rev limiter which might not be helping,just checking?
Your injectors could be two small, and as johnno mentioned check your runner lengths.
A mate also mention the cam ,fuel injection prefers a wider lobe separation for vacume 108 /110/112 Your cam may be two big?
I think the old standard 5L runs a 70 or 75mm tb one would think that would be enough for a six and less work than two as the bomber mentioned.
Does your computor system have a rev limiter which might not be helping,just checking?
Your injectors could be two small, and as johnno mentioned check your runner lengths.
A mate also mention the cam ,fuel injection prefers a wider lobe separation for vacume 108 /110/112 Your cam may be two big?
#22
_oldjohnno_
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Posted 16 February 2010 - 06:07 AM
Dont shoot me down just a few thoughts.
I think the old standard 5L runs a 70 or 75mm tb one would think that would be enough for a six and less work than two as the bomber mentioned.
Does your computor system have a rev limiter which might not be helping,just checking?
Your injectors could be two small, and as johnno mentioned check your runner lengths.
A mate also mention the cam ,fuel injection prefers a wider lobe separation for vacume 108 /110/112 Your cam may be two big?
Good points. A single 75mm flows the equivalent of about 580cfm so would be just big enough, a single 80mm would be ideal. I think the std VK was about 65mm, I'll drag one out and measure it later but two 65s would be plenty.
I'm concerned about the amount of overlap as well, and can see much of the fuel charge going straight out the exhaust. The fuel control will obviously have to be a crude rpm/tps only deal. Ideally the duration would be shortened a fair bit but the LSA widened to keep the inlet closing at somewhere near the same point. To be completely honest (and I know EFI-GTR has committed a lot of time and money to the injection system) if it was me I'd keep the cam and can the injection for some good carburetors. Maybe I'm a luddite but I think once you get to this stage of tune the main advantages of EFI (smooth and "civilised") are lost anyway, and good carbs will make power within a percent or two of injection.
I'd assume the injector flows and the rev limiter would have been checked while it was on the dyno. The VK manifold - because of it's length and tiny CSA near the port face - simply refuses to co-operate over the high 5s.
#23
_EFI-GTR_
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Posted 16 February 2010 - 03:49 PM
Dont shoot me down just a few thoughts.
I think the old standard 5L runs a 70 or 75mm tb one would think that would be enough for a six and less work than two as the bomber mentioned.
Does your computor system have a rev limiter which might not be helping,just checking?
Your injectors could be two small, and as johnno mentioned check your runner lengths.
A mate also mention the cam ,fuel injection prefers a wider lobe separation for vacume 108 /110/112 Your cam may be two big?
Good points. A single 75mm flows the equivalent of about 580cfm so would be just big enough, a single 80mm would be ideal. I think the std VK was about 65mm, I'll drag one out and measure it later but two 65s would be plenty.
I'm concerned about the amount of overlap as well, and can see much of the fuel charge going straight out the exhaust. The fuel control will obviously have to be a crude rpm/tps only deal. Ideally the duration would be shortened a fair bit but the LSA widened to keep the inlet closing at somewhere near the same point. To be completely honest (and I know EFI-GTR has committed a lot of time and money to the injection system) if it was me I'd keep the cam and can the injection for some good carburetors. Maybe I'm a luddite but I think once you get to this stage of tune the main advantages of EFI (smooth and "civilised") are lost anyway, and good carbs will make power within a percent or two of injection.
I'd assume the injector flows and the rev limiter would have been checked while it was on the dyno. The VK manifold - because of it's length and tiny CSA near the port face - simply refuses to co-operate over the high 5s.
#24
_EFI-GTR_
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Posted 16 February 2010 - 03:59 PM
Yeah ive had everything checked, the manifold just no good for n/a hi performance application.. Spoke to Gary Mckay who has the crazy lj race car and he thinks the six tb system is hard to beat...Morrison motorsport in lilydale can make all the bits (in billet alum) that i need for almost half the cost of the others i have found so far... So see how i go... Keep you all posted:)
#25
_coupe202_
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Posted 16 February 2010 - 04:18 PM
This is the custom manifold Ive been working on
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