turbo setup questions

[Mike750]

hi all new here with this project always had Suzuki but never a turbo,any help appreciate because I think I need some.its a 92 750 with 750 engine, water cooled front end with srad front calipers, 99 busa rear swingarm and k6 rear shock. so far ive got a dyna 2000 ingnition system with coil and taylor leads,turbo is off a saab 93 2l,and a mate has made my plen and all the pipe work. few questions are what fuel pump and fuel reg do people use ,and wheres the easiest place to pipe the return oil using a scavange pump,my carbs have been rebuilt aswel to standard and have replaced all new seals and rubbers??? thanks for any help and sorry for any stupid questions. oh and if I can get it started john o grady tunning said he willing to tune it from there. long way to go but ill get there!!

Edited October 13, 2016 by Mike750

[Mike750]

Any one guys?????

[Goo'Roo]

Heya

I would suggest to rebuild your carbs completey, with new emulsion tubes, stock needles and orings.

I use a walbro 255lph external fuel pump with a malpassi reg.

You can route the scavenge return in the clutch cover

[Mike750]

Thanks for the help il get shopping see what I can get.

[Reinhoud]

A fuel pump from a car what produces over about 200hp should be fine, for a fuel pressure regulator you need a Rising Rate Fuel pressure regulator (RRFPR), Maplpassi has good ones. 

Edited October 15, 2016 by Reinhoud

[Gixer1460]

Always wary about specifying EFI fuel pumps for use with carbs. EFI pressure is relatively constant over the injectors, flow is largely unimportant as it is usually in excess but choking down an efi pump a) over heats the fuel and b) reduces its flow - to carb float valve tolerable levels, so requiring an oversize tank return line. RR Regs are spawn of satan IMO - may be ok for a mildly hopped up NA situation but never good with a turbo and certainly not with turbo and carbs! Carbs need to have low pressure, high flow supply that will track boost exactly to remain constant - increasing FP exponentially with no regard to boost requirement leads to blown engines - seen it with Busa's done on the cheap.

Different pipe route - I like it, neat and tucked in. Stainless? won't shed heat easily so air could get a bit toasty!

[Mike750]

Have to look into this more don't wont to start melting engine straight away,what size vacuam pipes do people usually use from the plen to carbs and do you just use one off the plen and tee off then??ive read some people wire the fuel pump to the kill switch or oil pressure switch, kill switch sounds good to me .am I rite in saying this??

[Reinhoud]

20 hours ago, Gixer1460 said:

Always wary about specifying EFI fuel pumps for use with carbs. EFI pressure is relatively constant over the injectors, flow is largely unimportant as it is usually in excess but choking down an efi pump a) over heats the fuel and b) reduces its flow - to carb float valve tolerable levels, so requiring an oversize tank return line. RR Regs are spawn of satan IMO - may be ok for a mildly hopped up NA situation but never good with a turbo and certainly not with turbo and carbs! Carbs need to have low pressure, high flow supply that will track boost exactly to remain constant - increasing FP exponentially with no regard to boost requirement leads to blown engines - seen it with Busa's done on the cheap.

Different pipe route - I like it, neat and tucked in. Stainless? won't shed heat easily so air could get a bit toasty!

I might be misunderstanding you, but a lot what you wrote down doesn't make sense to me..

[Gixer1460]

What don't you understand? Most fuel pumps these days are sourced from EFI systems. The rated flows are generally at 3bar pressure and will be constant, what isn't used (@ 3bar pressure) will be bypassed back to the tank. If you drop the pressure to carb acceptable levels, the flow will drop accordingly. Other than that, what else needs explaining?

[Arttu]

10 minutes ago, Gixer1460 said:

If you drop the pressure to carb acceptable levels, the flow will drop accordingly.

Nope, flow increases if pressure is lower.

[Reinhoud]

On 10/15/2016 at 9:53 AM, Gixer1460 said:

.

Edited October 15, 2016 by Reinhoud

[Reinhoud]

On 10/15/2016 at 2:38 AM, Gixer1460 said:

Always wary about specifying EFI fuel pumps for use with carbs. EFI pressure is relatively constant over the injectors, flow is largely unimportant as it is usually in excess but choking down an efi pump a) over heats the fuel and b) reduces its flow - to carb float valve tolerable levels, so requiring an oversize tank return line. RR Regs are spawn of satan IMO - may be ok for a mildly hopped up NA situation but never good with a turbo and certainly not with turbo and carbs! Carbs need to have low pressure, high flow supply that will track boost exactly to remain constant - increasing FP exponentially with no regard to boost requirement leads to blown engines - seen it with Busa's done on the cheap.

Different pipe route - I like it, neat and tucked in. Stainless? won't shed heat easily so air could get a bit toasty!

-Flow is important. (But you say that later on)

-You don't choke the fuel pump more, in a car the pump is choked to about 2.5 to 3 bar, on a bike the pump is choked to about 1 to 1.5 bar, depending on boost level, so why would fuel temp go up?

-If you don't like RRRegs, how then adapt the pressure to wanted levels?

 

That's what I mean I don't understand..

[Gixer1460]

Arttu - I agree with the statement but subject to the plumbing. Example -take a tap, turn it off and it has zero flow and zero pressure at the outlet but substantial pressure and zero flow before the valve. Turn it on a little and pressure reduces and flow increases before the restriction but at the outlet flow increases but has zero pressure - it has a degree of force due to kinetics but no pressure. Open tap more and the effect increases but there is no more pressure at the outlet and it can only be generated before a restriction. A float valve only sees pressure when it is closed and not flowing anything?

Reinhoud - EFI in a car / bike uses a regulator to choke down the flow to give 3 bar over the injectors - excess pressure is bled off by flow back to the tank that has zero pressure (atmospheric) A carburettor needs (usually) no more than 0.1 bar fuel pressure or the float valve will leak and a carb placed in the same relationship as an injector would be subject to flooding initially / often as the regulator is trying to build 0.1 bar pressure on a line that is effectively leaking ie. into the carb and only when bowl is full and float valve shuts can line pressure of 0.1 bar be maintained? But the pump is putting out flow - flat out - which is mostly returned back to the tank but as with the tape example above the big flow has force that may overwhelm the float.

The other option is a dead head system where the pump output flows against a regulator that only allows sufficient fluid past not to overwhelm the float valve. The pump will be producing way in excess of 3-5 bar fuel pressure at idle rpms which unless effectively bled off by return to tank overheats the fuel.

A Rising Rate Regulator is NOT a Boost Referenced Regulator and they shouldn't be confused. The former will multiply the fuel delivery pressure by a fixed % ie 1lb boost fuel pressure increases by 3% so 43 psi becomes 44.29, add another lb of boost and it adds another 3% so 44.29 becomes 45.62 psi etc etc. Whereas a Boost referenced regulator will only add 1 psi for every 1lb of boost. This effectively means the carb jets or the injectors 'see' exactly the same pressure over them whatever the boost is - whereas with a RR reg the pressure at the jet / injector is higher than boost making the overall delivery richer and richer whether it is required or not! It may work if you can't adjust the map for limited boost increases but with 10lbs of boost you could be getting 65psi FP when you'd only need 50psi - remember compressing anything generates heat so personally i'd keep the pressure down and re-map the injector opening time up.........with a carb you'd be buggered IMO!

[MeanBean49]

Erm yeah a rising rate regulator with its referrence pipe conected to a pressurised part of the air system (carb top normally) will give a rising fuel pressure that rises exactly with boost but slightly higher  by however much you have set the base pressure at. Any excess fuel returns to the tank via the return line from the rrfpr. Doesnt heat the fuel up anymore than in an injection system.

I run 7psi to 17psi boost and my fuel curve remains perfect and constant any revs any boost.

 

[Arttu]

17 hours ago, Gixer1460 said:

Arttu - I agree with the statement but subject to the plumbing. Example -take a tap, turn it off and it has zero flow and zero pressure at the outlet but substantial pressure and zero flow before the valve. Turn it on a little and pressure reduces and flow increases before the restriction but at the outlet flow increases but has zero pressure - it has a degree of force due to kinetics but no pressure. Open tap more and the effect increases but there is no more pressure at the outlet and it can only be generated before a restriction. A float valve only sees pressure when it is closed and not flowing anything?

I'm not sure if I got your point here  Any way, if you use an EFI pump in carb system at lower pressure it will produce at least as much flow as on EFI system at higher pressure. In practice it will flow more at low pressure. And also fuel heating will be smaller at low pressure as the pump doesn't need to work as hard.

So generally I don't see any problem in using EFI pump with carbs and return style pressure regulator. Given that pump sizing is at correct ball park. Maximum pressure capability of the pump doesn't play any role there since the regulator will always keep the pressure lower by bleeding  excess fuel back to the tank. Important figure is pump flow at your working pressure. With deadhead regulator it would be completely different situation as the pump would push maximum pressure against the regulator when there is no flow to carbs.

[MeanBean49]

3 hours ago, Arttu said:

I'm not sure if I got your point here  Any way, if you use an EFI pump in carb system at lower pressure it will produce at least as much flow as on EFI system at higher pressure. In practice it will flow more at low pressure. And also fuel heating will be smaller at low pressure as the pump doesn't need to work as hard.

So generally I don't see any problem in using EFI pump with carbs and return style pressure regulator. Given that pump sizing is at correct ball park. Maximum pressure capability of the pump doesn't play any role there since the regulator will always keep the pressure lower by bleeding  excess fuel back to the tank. Important figure is pump flow at your working pressure. With deadhead regulator it would be completely different situation as the pump would push maximum pressure against the regulator when there is no flow to carbs.

I thought pretty much the same. Dont think he quite understands the way we are using variable fuel pressure regs.

Its not been a problem for hundreds of people with carbed bikes running the same setup.

Only problem i ever had was when i had a 130lph pump and i changed turbo. Just couldnt flow enough fir what i wanted. Swapped to a 260lph and its been fine

[Scara]

1. Using a pump like the Walbro 255lph will deliver to any EFI system effectively. That being said, any carbied system imo needs to have a return line to the tank otherwise you will end up with fuel flooding out of the plenum and into the turbo housing, hence as supplied with updated petcock it has return line capabilities etc. Effective use of the Malpassi (carb style) FPR which can be bought as a rising rate unit at 1.1:1 can be set to the carbies needs effectively along with the appropriate fuel gauge inserted after the FPR of 0 - 15 psi. Therefore the Walbro 255 can and will deliver. It must be pointed out, the FPR is fitted between the fuel pump and carbs.  Many people on this forum use such a set up, including me up until last month.

I include a schematic for use to everyone. NOTE: I found that connecting the Boost reference line ( in green ) from the FPR to the engine side of the carbs got a better reading for jetting rather than at the plenum, bike constantly flooded and gave me false tuning information. After consulting with Britain's foremost authority Dave Dunlop about it, he concurred and advised to move the line. Now, that was using the CV34SS vacuum carbs. Other larger and later models may differ and subsequently connecting to the plenum may be suitably fine and work without issue.

2. On EFI units tank connects to fuel pump, then fuel rail; naturally the FPR is fitted after the fuel rail and onto the return line if your fuel pump is constant on.; It goes without saying no return line is necessary if your aftermarket ECU has the capacity to monitor fuel pressure and cut off fuel delivery similar to any late model bike with an in-tank pump. Now, there are some fuel only controllers which have the facility to use an external pump and the menu allows for maximum fuel pressure then cuts it off. Example 45 psi for a 43.5 psi duty cycle requirement, no return line needed. One such system is the Microtech LT9C Fuel only controller, which can run along side an aftermarket system such as the Dyna 2000 and takes its delivery queue from the tacho.

Everyones answers here are indicative to their own bikes. My setup may not necessarily work on yours and so on. Everything depends on engine condition, modifications and so on and so forth. NO ONE has the exact same bike here, would never happen. There is a wealth of knowledge on this forum and all opinions are respected without question

Simple English for me, I'm a simpleton............Good luck with the project buddy

 

Edited February 24, 2018 by Scara

[Gixer1460]

1 hour ago, Scara said:

2. On EFI units tank connects to fuel pump, then fuel rail; naturally the FPR is fitted after the fuel rail and onto the return line if your fuel pump is constant on.; It goes without saying no return line is necessary if your aftermarket ECU has the capacity to monitor fuel pressure and cut off fuel delivery similar to any late model bike with an in-tank pump. Now, there are some fuel only controllers which have the facility to use an external pump and the menu allows for maximum fuel pressure then cuts it off. Example 45 psi for a 43.5 psi duty cycle requirement, no return line needed. One such system is the Microtech LT9C Fuel only controller, which can run along side an aftermarket system such as the Dyna 2000 and takes its delivery queue from the tacho.

That's a new one on me! I'm not aware of any OEM EFI systems that utilise what you describe. There may be sensors available that can respond to the difference between 43psi and 42psi but to turn a pump on and off repeatedly won't do it much good! In tank pumps generally have integral FPR's, so single line correct pressure is delivered constantly. I looked at the controller you indicated but it's nothing like what you describe - its an auxiliary injector controller not a pump controller, that works in association with the std ECU - its drivers don't have the capacity to control a pumps amp demands, even constantly, let alone startup current.

[Scara]

4 minutes ago, Gixer1460 said:

That's a new one on me! I'm not aware of any OEM EFI systems that utilise what you describe. There may be sensors available that can respond to the difference between 43psi and 42psi but to turn a pump on and off repeatedly won't do it much good! In tank pumps generally have integral FPR's, so single line correct pressure is delivered constantly. I looked at the controller you indicated but it's nothing like what you describe - its an auxiliary injector controller not a pump controller, that works in association with the std ECU - its drivers don't have the capacity to control a pumps amp demands, even constantly, let alone startup current.

I never said it would switch on and off during operation, you have assumed as much. I was speaking of key on to load injectors, like a modern bike. Obviously I did not make that clear. My mistake however, I did not clarify specifics > should have been the LT10C not the LT9C, and on that I stand corrected.

[Gixer1460]

Still doesn't make sense as every EFI system will pressurise the fuel system then turn off while cranking - the starter doesn't need the addition electrical load from the pump. As soon as a 'running state' is achieved the pump will turn on full time - whether it be internally regulated or after rail regulated with return. If it didn't, the fuel rail pressure would decay due to injectors pulsing - its why you can't keep an EFI system grinding away on the starter - eventually there would be no fuel pressure left in the rail!