custon throttle bodies
Discussion
Has anyone on here made their own throttle bodies?
The 'plate' or tube would be very easy to make, the spindle needs to be kept as small as possible I guess to prevent flow issues, but how much does the buttefly actually seal the 'hole'..fully and there is a separate air bleed- or the engine would get no air and stall, or a small (few thou) gap all round when throttle fully closed?
Just thinking out loud (which is what I am very good at!)
Virgil.
The 'plate' or tube would be very easy to make, the spindle needs to be kept as small as possible I guess to prevent flow issues, but how much does the buttefly actually seal the 'hole'..fully and there is a separate air bleed- or the engine would get no air and stall, or a small (few thou) gap all round when throttle fully closed?
Just thinking out loud (which is what I am very good at!)
Virgil.
chassis 33 said:
How about making a slide throttle, so there is no restriction at WOT?
Regards
Iain
Regards
Iain
It's harder to seal and produce a linear throughput at lower revs as I understnad it...fine for a full blown racing engine, not so good for road use...
Roller barrells similar issue for the sealing thing...I think.
Hi there,
well Ive had a go at ITB's and its not easy to tune, but Rob pointed out a fundemental problem in my design :-( Im not going to have another go at them now as having driven Rob's 5.5 with ACT triple throttles on it Im convinced that the plenum can be used to great effect. Im going to cut 2 plenums in half and weld them up so as I get 2 throttle openings (one either side) should look great too.
Phil
well Ive had a go at ITB's and its not easy to tune, but Rob pointed out a fundemental problem in my design :-( Im not going to have another go at them now as having driven Rob's 5.5 with ACT triple throttles on it Im convinced that the plenum can be used to great effect. Im going to cut 2 plenums in half and weld them up so as I get 2 throttle openings (one either side) should look great too.
Phil
Dont forget guys one large throttle body is better than 8 small ones, unfortunetly there is not a plenum on the market yet to counter act the downsides of running a plenum ie reversal and a fresh charge sucking in clean air as opposed to crap air that a cylinder has just filled it with! a good 4 barrell carb will make more horsepower than 8 individual throttle bodies due to the fact that a 700 webber/holley etc... can flow 700 cfm to each cylinder..., as far as throttle bodies go slide plates are ultimetly the way to go in my expeience but as mentioned earlier are a b****** to seal correctly!
daxtojeiro said:
Hi there,
well Ive had a go at ITB's and its not easy to tune, but Rob pointed out a fundemental problem in my design :-( Im not going to have another go at them now as having driven Rob's 5.5 with ACT triple throttles on it Im convinced that the plenum can be used to great effect. Im going to cut 2 plenums in half and weld them up so as I get 2 throttle openings (one either side) should look great too.
Phil
well Ive had a go at ITB's and its not easy to tune, but Rob pointed out a fundemental problem in my design :-( Im not going to have another go at them now as having driven Rob's 5.5 with ACT triple throttles on it Im convinced that the plenum can be used to great effect. Im going to cut 2 plenums in half and weld them up so as I get 2 throttle openings (one either side) should look great too.
Phil
Phil you, me and several others have all considered this. There was a thread about it on here quite a while ago - Nick Smallwood has done one, I have contacted him a few times about progress - and he's still ironing out issues. Someone on here said last time that TWR tried and they had issues and abandoned it. We are still considering the idea, but with some sort of divider in the middle.
Also, if you do go ahead - dont cut two plenums down the middle as you will have to redo the idle stepper flange - instead cut to one side of it, so the join goes along the outermost edge (does that make sense?).
Also, apart from an interesting project/coolness - does it need it? - My mates griff 500 doesn't drop any kpa at wot [now that the AFM is removed] and that's on a std 65mm throttle.
I'm thinking along the lines of just making a new plenum top from 5mm sheet, with a pair of 50mm TB's to one side.
Edited by eliot on Wednesday 2nd August 21:33
eliot said:
daxtojeiro said:
Hi there,
well Ive had a go at ITB's and its not easy to tune, but Rob pointed out a fundemental problem in my design :-( Im not going to have another go at them now as having driven Rob's 5.5 with ACT triple throttles on it Im convinced that the plenum can be used to great effect. Im going to cut 2 plenums in half and weld them up so as I get 2 throttle openings (one either side) should look great too.
Phil
well Ive had a go at ITB's and its not easy to tune, but Rob pointed out a fundemental problem in my design :-( Im not going to have another go at them now as having driven Rob's 5.5 with ACT triple throttles on it Im convinced that the plenum can be used to great effect. Im going to cut 2 plenums in half and weld them up so as I get 2 throttle openings (one either side) should look great too.
Phil
Phil you, me and several others have all considered this. There was a thread about it on here quite a while ago - Nick Smallwood has done one, I have contacted him a few times about progress - and he's still ironing out issues. Someone on here said last time that TWR tried and they had issues and abandoned it. We are still considering the idea, but with some sort of divider in the middle.
Also, if you do go ahead - dont cut two plenums down the middle as you will have to redo the idle stepper flange - instead cut to one side of it, so the join goes along the outermost edge (does that make sense?).
Also, apart from an interesting project/coolness - does it need it? - My mates griff 500 doesn't drop any kpa at wot [now that the AFM is removed] and that's on a std 65mm throttle.
I'm thinking along the lines of just making a new plenum top from 5mm sheet, with a pair of 50mm TB's to one side.
Edited by eliot on Wednesday 2nd August 21:33
Hi Elliot,
yep sorry, I meant cutting it so as to keep the idle assembly so it can be re-used, I have yet to get a 2nd plenum that I can mess about with but Ive been promised one by a mate and hope to get it all done very soon. My 5.0L developes a vacuum above 2500RPM without an AFM and filter (only run it without a filter to test it) In fact at 5000RPM Im losing 5-6KPa (5-6%) Even Rob's 5.5L with the ACT triple plenum creates a vacuum of 4KPa at 6000RPM. I wonder where your mate is measureing the map, possibly on the vacuum advance point?? I measure it at the idle assembly as this is inside the plenum and should be a fairly accurate representation,
Phil
GreenV8S said:
A drop of 4kPa is incredibly low and not worth bothering to tackle imo.
Yep, it's just over half a psi so is worth probably 5 bhp out of 250-300 bhp so about 2% or so.
Can be resolved anyway by putting a scoop at the front of the car to create pressure in the air box/plenum. It's possible to get 0.25psi at about 70mph and obviously more the faster you go, with a fairly small, simple scoop.
Phil,
Ive pinged my mate to clarify the KPA drop - he's running the little carbon fibre trumpets. Even when he did get a drop it was only at the top-end. I'm suprised your seeing it down so low.
We have a pair of plenums sat on the shelf waiting for me to do the work. But before that I'm going to play with making a soldid bellmouth arrangment, as being discussed on this thread:
www.v-8.org.uk/forum/topic.asp?TOPIC_ID=4680
I need a standard RR trumpet base to start with though, as my mates "OEM" TVR base has already been bored out to much, causing the inlets to break into each other.
Ive pinged my mate to clarify the KPA drop - he's running the little carbon fibre trumpets. Even when he did get a drop it was only at the top-end. I'm suprised your seeing it down so low.
We have a pair of plenums sat on the shelf waiting for me to do the work. But before that I'm going to play with making a soldid bellmouth arrangment, as being discussed on this thread:
www.v-8.org.uk/forum/topic.asp?TOPIC_ID=4680
I need a standard RR trumpet base to start with though, as my mates "OEM" TVR base has already been bored out to much, causing the inlets to break into each other.
Hi there Phil! In the early 90's I was heavily involved in the development and tuning of a 3.9 Rover unit for use in our TR7 V8 circuit racer. On a visit to John Eales for an engine dyno session I spotted a dual inlet plenum on a shelf. It had an inlet on each side, made by a cut and shut job using two standard plenums.( Should that be plena?) John said it was a development dead end and produced no extra power. He said that putting both throttle bodies on one side worked better. We stayed with a single butterfly, albeit enlarged to 68mm, oversized trumpets inside a standard plenum and no air flow meter.Over 300bhp through a single butterfly. The dual entry plenum did look cool though! Two sets of bike throttle bodies would look cool as an alternative.
SPYDER DRYVER said:
John said it was a development dead end and produced no extra power. He said that putting both throttle bodies on one side worked better. We stayed with a single butterfly, albeit enlarged to 68mm, oversized trumpets inside a standard plenum and no air flow meter.Over 300bhp through a single butterfly. The dual entry plenum did look cool though! Two sets of bike throttle bodies would look cool as an alternative.
That's what I heard last time this subject was discussed on here, perhaps it was you who clarified it. (Phil has already tried 8 bike throttle bodies)
WRT to the rover trumpets, Ive got the plenum base from the Belguim and Ive started making a prototype from plastic. Ive also now priced a chunk of ally for it too. You can follow it's progress on the this forum
SPYDER DRYVER said:
Hi there Phil! In the early 90's I was heavily involved in the development and tuning of a 3.9 Rover unit for use in our TR7 V8 circuit racer. On a visit to John Eales for an engine dyno session I spotted a dual inlet plenum on a shelf. It had an inlet on each side, made by a cut and shut job using two standard plenums.( Should that be plena?) John said it was a development dead end and produced no extra power. He said that putting both throttle bodies on one side worked better. We stayed with a single butterfly, albeit enlarged to 68mm, oversized trumpets inside a standard plenum and no air flow meter.Over 300bhp through a single butterfly. The dual entry plenum did look cool though! Two sets of bike throttle bodies would look cool as an alternative.
Hi there Spider, I can see that on a 3.9 then there would be no gain as the standard intake should just about be big enough, especially without the AFM on it. But on a 5.0L then there is a restriction with a single intake, I would think as long as the air got in then it wouldnt matter what side it came from but im no expert and havent tested any of this. All I know is theres a restriction with a single intake and Im hoping it will be gone with 2, if thats the case then surely thats an increase n power?
Ohh, I have another idea about the ITB's, got a lot of work to do on them but I think the new idea will be a lot easier to fit,
Phil
Edited by daxtojeiro on Saturday 12th August 21:59
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