Triumph ITB - AEM Infinity Project

[Nux]

Are you guys using standard cams on these conversions?

I'm going to convert my 3.2SS which is already running the Bitz kit EFI (with great succes). With a 113 degree lobe (correct me if I'm wrong), the standard SC cams may provide a sufficient MAP signal from the ITB's, but other cams may be a bit difficult to tune?

I'll probably change to 993SS cams this winter when I pull the engine - but I know my self good enough to know I can't resist installing those gorgeous ITB before that.

[Clay.0]

I'm using E cams in my 2.8l

[quint22cp]

I'm using a John Dougherty dc20 cam on my 3.5L

Just to report back on how things have been going since I fitted these ITBs as some people must be thinking is it worth the effort.

Well the induction roar is awesome and torque has shifted down the rev range which makes it more drive-able on a street car. I put this down to a couple of things, I am using the original Triumph injectors that came with the Triumph TBs. These have a good spray pattern coupled with a higher fuel rail pressure (3.5 bar). My inlet manifolds are short so the butterfly's are closer to the ports and this gives more air turbulence at small throttle openings and hence better fuel distribution.

On the down-side, the Triumph TBs are designed to be used on a motorcycle with a twist-grip throttle running with a cable. Therefore the butterfly return springs are heavy to overcome cable drag and there are 3 one for each TB. Now add in another 3 TBs and that is 6 heavy springs. This all adds up to quite a lot of spring pressure to work against and this make the pedal heavy and puts a fair bit of strain on the pedal linkage.

I am currently using short cables to connect my TBs to a common crank but even without cables and using a mechanical linkage the springs are still there. It could be possible to use lighter springs but not with my cable setup, I have already tried that, cable drag is too great.

My thoughts are to use a secondary throttle shaft running parallel with the throttle spindles and then linking each butterfly to this shaft independently, doing away with the linkages between TBs and also therefore getting rid of the springs, I now only need 1 spring on the new shaft.
Well that's the theory, I am currently machining parts for a conversion this winter.

[wiggle_puppy]

Originally Posted by quint22cp

On the down-side, the Triumph TBs are designed to be used on a motorcycle with a twist-grip throttle running with a cable. Therefore the butterfly return springs are heavy to overcome cable drag and there are 3 one for each TB. Now add in another 3 TBs and that is 6 heavy springs. This all adds up to quite a lot of spring pressure to work against and this make the pedal heavy and puts a fair bit of strain on the pedal linkage.

I am currently using short cables to connect my TBs to a common crank but even without cables and using a mechanical linkage the springs are still there. It could be possible to use lighter springs but not with my cable setup, I have already tried that, cable drag is too great.

My thoughts are to use a secondary throttle shaft running parallel with the throttle spindles and then linking each butterfly to this shaft independently, doing away with the linkages between TBs and also therefore getting rid of the springs, I now only need 1 spring on the new shaft.
Well that's the theory, I am currently machining parts for a conversion this winter.

It's interesting to hear this. I'm running Triumph throttle on my SC with the ClosedCourseMotorsports throttle linkage and haven't experiencing a problem with a heavy throttle. In fact I found it necessary to add a secondary throttle return spring to the bellcrank to supplement the springs on the throttles themselves as otherwise my throttle wouldn't snap shut quickly.

[al lkosmal]

Originally Posted by wiggle_puppy

It's interesting to hear this. I'm running Triumph throttle on my SC with the ClosedCourseMotorsports throttle linkage and haven't experiencing a problem with a heavy throttle. In fact I found it necessary to add a secondary throttle return spring to the bellcrank to supplement the springs on the throttles themselves as otherwise my throttle wouldn't snap shut quickly.

+1.......I build systems using Triumph Speed Triples, PMO, TWM etc......the speed triple return springs do not seem to be any stronger that any of the others....in fact, many people are adding another return spring, as mentioned above, to ensure a snappy return.


regards,
al

[Clay.0]

I'm with al lkosmal and wiggle_puppy on that, no issues here.

It sounds like a binding issue somewhere along the line to me

[quint22cp]

Nothing binding or caught up. Everything moves smoothly. I am however using a cable system and there is drag in the cables as they have to turn 180deg to get a nice smooth cable run with no sharp bends. Anyone else using cables or are you all on mech' linkages ?

Which Triumph TBs are you using, I have looked into this and they do differ from year to year and bike to bike. Mine were from a 1050cc Sprint 2004 (I think).

Pete

[Nux]

Originally Posted by quint22cp

I'm using a John Dougherty dc20 cam on my 3.5L

Just to report back on how things have been going since I fitted these ITBs as some people must be thinking is it worth the effort.

Well the induction roar is awesome and torque has shifted down the rev range which makes it more drive-able on a street car. I put this down to a couple of things, I am using the original Triumph injectors that came with the Triumph TBs. These have a good spray pattern coupled with a higher fuel rail pressure (3.5 bar). My inlet manifolds are short so the butterfly's are closer to the ports and this gives more air turbulence at small throttle openings and hence better fuel distribution.

On the down-side, the Triumph TBs are designed to be used on a motorcycle with a twist-grip throttle running with a cable. Therefore the butterfly return springs are heavy to overcome cable drag and there are 3 one for each TB. Now add in another 3 TBs and that is 6 heavy springs. This all adds up to quite a lot of spring pressure to work against and this make the pedal heavy and puts a fair bit of strain on the pedal linkage.

I am currently using short cables to connect my TBs to a common crank but even without cables and using a mechanical linkage the springs are still there. It could be possible to use lighter springs but not with my cable setup, I have already tried that, cable drag is too great.

My thoughts are to use a secondary throttle shaft running parallel with the throttle spindles and then linking each butterfly to this shaft independently, doing away with the linkages between TBs and also therefore getting rid of the springs, I now only need 1 spring on the new shaft.
Well that's the theory, I am currently machining parts for a conversion this winter.

Interesting! I've just puchased DC20 cams for my 3.2SS, which I'm converting to ITB as we speak. I just got some advice from Al (Kosmal) on injector options, as my current Accel ones are physically too big to fit in the thriumph Throttle bodies. But you are using the original ones?

Martin

[quint22cp]

Yes the original ones aren't special to Triumph they are used on cars as well (European cars that is). I flow tested all 6 and they were a close match. At 3.5bar pressure (55psi ish) they flow 30lbs 315cc with a good spray pattern.

[Nux]

Originally Posted by quint22cp

Yes the original ones aren't special to Triumph they are used on cars as well (European cars that is). I flow tested all 6 and they were a close match. At 3.5bar pressure (55psi ish) they flow 30lbs 315cc with a good spray pattern.

Do you have a parts nr on those?

[quint22cp]

I have 6 of the 1240891.

If you look back through this thread, I think it was Al, posted all of the part numbers and flow figures.

[pampadori]

I had started out using cables and at that time I unwound one of the three throttle return springs on each bank of throttle bodies. Effectively providing 66.6% of the closing pressure. You might try that but I would guess that you are feeling the cable drag thru that 180 degree bend. For what Clay charges for this throttle setup, its worth ditching the cables IMO.

I'm also running the factory triumph injectors. my setup is from a Daytona T595 with the aluminum fuel rails. Stock SC or 3.2 cams, i can't remember. I have only ever driven my own 911 and one other 83 SC with CIS. I feel a good punch around 3,000 over what the CIS had too.

Say, when are we all going to share some maps? I want to see who is the most aggressive with their timing! maybe another thread so as not to derail this one.

[Clay.0]

Originally Posted by pampadori

Say, when are we all going to share some maps? I want to see who is the most aggressive with their timing! maybe another thread so as not to derail this one.

I agree, the more info the better!

I don't mind maps and any info related to Triumph ITB's posted here

[quint22cp]

I don't believe it those Triumph TR6 boys have stolen my throttle shaft idea.





Being honest I saw this approach to linking TBs when I was at a recent classic car rally, shame I didn't see it earlier before I went down the cable route, hindsight, it's a wonderful thing.



.

[stlrj]

Looks very nice but it seems the injectors are located a bit too far from and not aimed at their intended target, the back of the intake valves as is standard in automotive engineering design. Deposition of fuel on the inside wall of the manifold may not be ideal.

Just an observation FWIW.


Cheers,

Joe

[quint22cp]

Originally Posted by stlrj

Looks very nice but it seems the injectors are located a bit too far from and not aimed at their intended target, the back of the intake valves as is standard in automotive engineering design. Deposition of fuel on the inside wall of the manifold may not be ideal.

Just an observation FWIW.

Hi Joe,
I'm right with you on this one and that is why I opted to space my TBs further apart to get a straight shot at the back of the valve (see my earlier posts in this thread). It is also why I made a big rod for my own back as connecting the TBs together has become a challenge because I can't use the original Triumph linkage.
Just to add to your point though, it is only important to hit the back of the valve at lower air flow as this improves fuel distribution. As air speed increases (more towards WOT), the fuel needs to be introduced earlier to ensure complete mixing. Now I don't think this is the thread for a discussion on the finer points of air-fuel dynamics but as Clay opened this thread I am now looking to him to take this Triumph ITB project to it's ultimate conclusion and add a second set of injectors atop the air filter shooting down the trumpets, that would be awesome, any takers ?


Here's some I just lashed together this morning






Pete

[stlrj]

Hi Pete,

You're way ahead of me and possibly read my mind.

By the way, I'm not so sure the second set of injectors is really necessary unless you feel a need to make it more complicated. Sizing the primary injectors properly might be more than adequate.

Keep up the good work.


Cheers,

Joe

[Tremelune]

Random thought: Isn't fuel on the back of the valves the thing that prevents the carbon buildup that plagues modern direct injection motors?

[Tippy]

Injectors close to valve is best for idle, injectors farther upstream are good for peak hp.

[sithot]

This hot shot has high injectors on the intake stacks. The OEM's are in the regular position. 2nd stage setup comes on at higher rpm. Runs like a scalded rat. Yamaha R1 tuned to around 200hp. Car weighs "nothing". Driver showed Ferraris the tail lights on T.O.D.. rally. Said owners not amused at being embarrassed by a sub $15,000 car.
Think of it as a "Radical" that's not quite as radical and looks like a Bugeye.