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[QUOTE=911st;4752351]stup,

The Control Pressure as he is manipulating with the Andial FV dose effect the metering arm pressure significantly.

911st...Just to let you know i was not talking about the lamda FV,,I was though talking about the FV he is using to manipulate the control pressure,,

It is very similar to the set up i have and i currently have mine open at a maximum setting of 80% to acheive correct AFR with my mentioned control pressure flow rate fuel volume.

My Frequency valve (FV) which manipulates control pressure via Greddy controller



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"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.
Old 06-30-2009, 03:07 PM
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Stup,

Well done!

Sounds like 75 Lite's set up.

Do you run your system at close to zero at idle and or cruse?

Or do you run it a say 50%, reset CO, and pull it back when the factory enrichment goes to rich?

With my system I disabled the factory enrichment and used the Bypass FV for any enrichment.
Old 06-30-2009, 03:31 PM
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Factory enrichment is disconnected and i just run freq valve closed at idle and light throttle, then i start to open when inlet pressure starts transition to positive pressure!

Works great with by far best results i have seen over other systems i have tried/tested on our turbo cis engines......Far less complicated also with no where near the fiddling of other systems.

I could basically tune near any AFR curve with minimum adjustments i have found.
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http://www.porscheinspections.com/
"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.
Old 06-30-2009, 04:01 PM
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You know what you are doing!

Few seem to understand this stuff and how well this approach can work.

Are you using your system to reduce lag and increase throttle response (drop & catch)?

Off idle and cruse I went instantly from +14.1 to about 13/1. No lean spot with accel like stock.

With this and my mod to keep the compressor bypass valve open and turbo spinning faster at idle and cruse and close with acceleration, I could almost blip it like an EFI motor.

The best.
Old 06-30-2009, 04:17 PM
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So, as I said before, and I wisely suggested by Keith, I succeed to trigger the lambda frequency valve to constant 75% duty cycle. ( it is very easy to do, just need to lead a wire from enrichment controller to the ground) In the same time, my AIC + freq valve was programmed to 80% duty cycle ( between 4500 and red line). . So the CP was down to 1.2 bar !!!

Here are the results




As can be seen, this setting provides a very fat mid ( 9.5). So there is absolutely no doubt about the fact that the triggered lambda frequency valve ( constant75% duty cycle) can provide additional fuel in the mixture.

However, from this curve, we can see the AFR is still increasing according the RPM. It's still too lean above 5200 RPM. The fuel mixture improvement is proportionally reduced and killed versus RPM ( no any improvement above 5700 RPM).

In the mean time, I also tested to increase the fuel mixture by adjusting the CO screw. Sorry I didn't keep the measurement but it didn't bring any improvement at high RPM. The throttle and low RPM AFR were not modified too. ( The lambda regulation makes it job). I just noticed an AFR modification under pre boost and boost and below 5000 RPM. But still no improvement at high RPM.


It seems that I hit the wall.....

At that time, I couldn't understand why the injection head could not supply more fuel while the lower chamber pressure was decreased by acting on the lambda frequency valve. I did understand why the CP dropping could not bring more fuel .... but I couldn't understand why mixture screw adjustment couldn't provide more fuel on top. ( while under less boost pressure, it gave some…) If the theory of small "hidden" metering plate travel was true, I should have been able to get more fuel on the max rev by playing with screw mixture. If the theory of the head flow adjusting was correct, I could get more fuel on top by acting on the lambda freq valve (differential pressure is increased in theory ).

In the same time, I saw and read the experience of one other member here ( STU) who met the same kinds of limit on his car. His car setup is very closed to mine ( SC cams , 1 bar of boost pressure, cata bypass etc)….From many experiences and opinion here, I should accept the idea to increase the fuel flow of my head (as some members did here) ... Remove the fuel head, send it to a BOSCH workshop ( who can do the good job...) and so on.....

So I wasn't happy with the idea to send my head to the workshop and I was not convinced the head was the limiting device in the CIS chain. Anyway, by the experience of many… it’s a “must have” …no other choice.

So prior to modify it, I just thought it would be better to make sure about fuel supply capability. As said before, according the Porsche manual, the fuel supply capacity was correct (1.7 L / 30sec and 7 bar for system pressure) .... ok .... but one question however , was it enough considering my car setup ????

As I wanted to make sure about the fuel supply capability, I thought I should find a stronger front fuel pump. ( basically, the rear pump can not invent fuel…it can only gives the fuel that the front pump provides ) After a brief investigation, I found the “044” Bosch pump can provide about 15% more fuel compare to the stock front fuel pump. I checked the dimensions and found it can be installed into the front compartment. ( It is a bit tight , that’s true) So I decided to buy this new fuel pump for the front. In the mean time, in order to make 100%, I also bought a new original rear fuel pump ( just to replace the old one by a brand new one) .

Here is the new front up graded fuel pump






And this is the result ……. With disable WUR boost line, with 10% to 40% duty cycle only on my AIC+Freq valve above 4000 RPM only ! and with almost 1.05 bar of boost pressure at high RPM !!! of course the 75% lambda freq. valve “hi jacking” has been removed.





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Last edited by Thierry25; 07-01-2009 at 12:44 AM..
Old 07-01-2009, 12:21 AM
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Great results Thierry!
So this means that not the fuel head but the front fuel pump was the limiting factor.
where did you buy the upgraded fuel pump and how much €€€ ?
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Old 07-01-2009, 12:59 AM
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Quote:
Originally Posted by gogomobil View Post
Great results Thierry!
So this means that not the fuel head but the front fuel pump was the limiting factor.
where did you buy the upgraded fuel pump and how much €€€ ?
Hello !

Yes, this is exactly what it means....so far the 1st limiting factor is the fuel pump. (assuming the pressure controle is correctly decrease ). The head flow limit is much higher than general belief. Of course, increase the head flow will provide more fuel .... but this improvment solution is only a way to deal with the orginal lack of the fuel supply system. Moreover it brings more fuel at every RPM. So it needs to modify other settings ( warm CP, CO screw etc) in order to get suitable.

For me, it is much more efficient and easy to modify the pump(s) than to deal with head flow adjustment, metering plate & pins modification or lambda system modification.

I bought the "044" fuel pump in France. I think you can easily find it in US ... no problem !
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Old 07-01-2009, 01:45 AM
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Thats interesting that installing the larger Bosch 044 motorsports fuel pump in front next to the gas tank gave you more fuel at high rpms than the origonal front pump.
That would mean your origonal front fuel pump couldn't supply enough fuel volume and pressure to maintain the same system pressure at high rpms and full throttle. It is possible your front pump was probably tired, worn, or compromised somehow.

What do you mean when you said, "assuming the pressure controle is correctly decrease "

It would have been nice to hook up a CIS fuel pressure gauge and check system pressure while your car was on the dyno at full speed and throttle and see what the system pressure was dropping to with your origonal front pump.

Other folks have replaced the origonal fuel pumps with the mass produced generic bosch 044 motorsports pump(s) because it's almost half the price of the limited production origonal equipment bosch fuel pump(s) and it flows more fuel at a steady 45psi which is where efi systems run. CIS runs at a steady 95psi...

I have not read in anyone's posts that the 044 pump gave them a richer mixture at high rpms but maybe it does and no one's mentioned it. Some people have installed two 044 pumps, replacing both the origonal pumps with them.

Did you have to do any modifications to the front fuel lines or fitting on the pump to install it? Is it thicker or longer than the origonal pump, or both?

Thanks for all the cool research and information you've done and posted.
Old 07-01-2009, 10:11 AM
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Quote:
Originally Posted by WinRice View Post
Thierry,

Just for fun, run two tests. Don't change your AIC settings, but run one with the MAP line hooked up to the WUR and one without. Just to see how the AFR looks at the highend.
Interesting question !

It doesn't change anything on the high rpm. ....and it's logical

Actually the AIC frequency valve is routed in parallel of the WUR. ( Remember the CIS head "see" one control pressure output only ....)

On one branch , If the Freq valve is runned at 90% durty cycle , the control pressure drop to 1.2 bar ....
On the parallel branch, if the WUR boost line ( I think you called it MAP line) is sending 1bar information to the WUR; the CP will drop to arround 2.9 bar...

When both devices are driven in parallel, the controle pressure will just down a bit under 1.2 bar ..........

The CIS head doesn't care if this value is obtained by the AIC or by the WUR or by by both devices at the same time! CP is CP ( no matter if it is regulated by the WUR or/and the freq valve) and it doesn't bring more fuel ( CP is already too low) Actually it even provides a very little bit less fuel on top end. Yes , not kidding,

By the way, this CP value (1.2 bar) is really too low for a correct CIS working.
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Old 07-01-2009, 10:34 AM
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[/QUOTE]

This exactly what I mean ! Original fuel pump is not able to maintain system pressure & flow, somewhere no matter the RPM and throttle , but versus the whole fuel flow which is need. In fact the total supplied fuel flow = injectors flow + losen flow. For a minor ratio, the lost are due to the fuel line structure as you mentionned. But the main losen flow is due to the CIS structure it self. The WUR device , the lambda device and the fuel system pressure regulator lead a huge qty of fuel directly back to the tank !


Quote:
Originally Posted by JFairman View Post
It is possible your front pump was probably tired, worn, or compromised somehow.
Yes it could be that.
- However, it has been controlled using the Porsche procedure and my original pumps provided 1.7 liters /30 sec ( Porsche recommendation is 1.5 if I am correct).... on these 1.7 liters, how much go back to the tank ???
- In the mean time, my fuelling was perfect while I kept 0.92 bar of boost.... lean AFR start to occur while I increased boost pressure to 1 bar until red line....
- STUP which has very close setup to mine. He met roughly the same limit... does it means that his pumps is worn too ?

The way peoples usually solve this problem is to increase the head fuel flow. Just think, when the head fuel flow capacity is increased it allows more fuel to come to the engine under a given fuel system pressure. When head fuel flow is increased , it becomes easier for the fuel to go inside the injector than to return back to the tank. When people are shimming the fuel system pressure regulator, it becomes harder for the fuel to go back to the tank ...and it becomes easier for the fuel to go inside the head to supply the WUR and Injectors. That's why head fuel pressure regulator shimming provides a very little (and partial) improvement...not because the system pressure increase..... Just because it reduces the flow of the fuel which is sent back to the tank !



Quote:
Originally Posted by JFairman View Post

What do you mean when you said, "assuming the pressure control is correctly decrease "
Once again sorry for my poor english skills I just mean that a simple pump upgrade won't provide more ( or enough) fuel at the top end. A suitable CP adjustment ( whatever you want to use ... frequency valve, adjustable WUR or DWUR) will allow a fine tuning of the AFR.

Quote:
Originally Posted by JFairman View Post

It would have been nice to hook up a CIS fuel pressure gauge and check system pressure while your car was on the dyno at full speed and throttle and see what the system pressure was dropping to with your original front pump.
yes, that's true, it would have been nice !


Quote:
Originally Posted by JFairman View Post


Other folks have replaced the origonal fuel pumps with the mass produced generic bosch 044 motorsports pump(s) because it's almost half the price of the limited production original equipment bosch fuel pump(s) and it flows more fuel at a steady 45psi which is where efi systems run. CIS runs at a steady 95psi...

I have not read in anyone's posts that the 044 pump gave them a richer mixture at high rpms but maybe it does and no one's mentioned it. Some people have installed two 044 pumps, replacing both the origonal pumps with them.
044 fuel pump can provide more fuel flow at all pressure range . The price wasn't my direct purpose . As you mentioned , CIS works at higher pressure than EFI....so this is also a good reason to increase the fuel supply capability. EFI system doesn't send such large fuel volume back to the tank as the CIS do !



Quote:
Originally Posted by JFairman View Post

Did you have to do any modifications to the front fuel lines or fitting on the pump to install it? Is it thicker or longer than the origonal pump, or both?

Thanks for all the cool research and information you've done and posted.
It was quite easy to install. I just bought the fitting and adapter to SUMMIT. I can let you know the detail of the fitting if you need. The pump has the same diameter but it is a bit longer. It is a bit tight in the front compartment but it can be installed without big hassle.

It is my pleasure to share my small experience and to exchange idea with all members here !
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Old 07-01-2009, 12:28 PM
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Old 07-01-2009, 02:10 PM
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Quote:
Originally Posted by Thierry25 View Post
Interesting question !

It doesn't change anything on the high rpm. ....and it's logical

Actually the AIC frequency valve is routed in parallel of the WUR. ( Remember the CIS head "see" one control pressure output only ....)

On one branch , If the Freq valve is runned at 90% durty cycle , the control pressure drop to 1.2 bar ....
On the parallel branch, if the WUR boost line ( I think you called it MAP line) is sending 1bar information to the WUR; the CP will drop to arround 2.9 bar...

When both devices are driven in parallel, the controle pressure will just down a bit under 1.2 bar ..........

The CIS head doesn't care if this value is obtained by the AIC or by the WUR or by by both devices at the same time! CP is CP ( no matter if it is regulated by the WUR or/and the freq valve) and it doesn't bring more fuel ( CP is already too low) Actually it even provides a very little bit less fuel on top end. Yes , not kidding,

By the way, this CP value (1.2 bar) is really too low for a correct CIS working.
Yep, that's what I was getting at. Just to see if you were getting the lowest CP possible, and if that low CP really made the difference we might assume. Looks like you hit the magic number.

It would have been interesting to see the fuel supply pressure drop at the head, max RPM, before and after the 044 swap. The stock system may be marginal at much higher HP levels.

Your latest AFR curve looks good!
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Old 07-01-2009, 09:35 PM
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Quote:
Originally Posted by WinRice View Post
It would have been interesting to see the fuel supply pressure drop at the head, max RPM, before and after the 044 swap. The stock system may be marginal at much higher HP levels.

Your latest AFR curve looks good!
Indeed!

It would be a great idea to watch system pressure for fall off at stock and shimmed level at high RPM/HP.
Old 07-02-2009, 08:17 AM
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Quote:
Originally Posted by 911st View Post
Indeed!

It would be a great idea to watch system pressure for fall off at stock and shimmed level at high RPM/HP.
Yep, you can have 2 pumps that deliver the same volume at free-flow, but under pressure one may drop the volume more than the other.
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Old 07-02-2009, 08:44 AM
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Quote:
Originally Posted by 911st View Post
Indeed!

It would be a great idea to watch system pressure for fall off at stock and shimmed level at high RPM/HP.
Hello Keith

Sorry but what do you mean by shimmed level ? Do you mean with pressure regulator shimming ?
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Old 07-02-2009, 09:05 AM
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Quote:
Originally Posted by WinRice View Post
Yep, that's what I was getting at. Just to see if you were getting the lowest CP possible, and if that low CP really made the difference we might assume. Looks like you hit the magic number.

It would have been interesting to see the fuel supply pressure drop at the head, max RPM, before and after the 044 swap. The stock system may be marginal at much higher HP levels.

Your latest AFR curve looks good!
And I can even get about 10.7 if I want to ... ( just need to go at 80% duty cycle on the AIC ) .....

Yes, it would have been on good thing to see the fuel pressure.
However it is a not an impressive variation since the pump deliver almost the same flow rate versus pressure. even if the metering plate if full open , the head chambers valves + injectors are still an important restriction of the circuit. So the pressure is not drop too much ...

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Old 07-02-2009, 09:45 AM
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Quote:
Originally Posted by WinRice View Post
Yep, you can have 2 pumps that deliver the same volume at free-flow, but under pressure one may drop the volume more than the other.
Yes I thought in this way too ! That's true that the Porsche testing procedure is a free flow test. The fuel supply is disconnected of the head and we just measure the fuel qty which is provided at the output of the fuel system ( just right after the fuel filter )....so yes, the maximum fuel supply flow is measured during this procedure... since the total restriction ( seen from the filter output) is equal to 0 . No restrication = maximum flow ( and less current in the pump because easier job)

Now, you are agree that if we close the fuel supply output, the pressure will increase a lot ( maybe 11 bar) and the absorbed power by the pump will be at it maximum right ? ( It will probably die very quickly )

Now when we make the fuel system pressure testing as stated in the manual , everything is connected. Right ? So the fuel system pressure regulator is working and the WUR are connected ( warm pressure 4.5 bar) . Right ? Both of them do their job and there is a fuel flow which comes from fuel supply and which go back to the tank. right right ? There is absolutely no fuel which are going to injector since the metering plate is totally closed ? right ? As the lambda freq valve is off, there is no fuel flow which in this device right ? So the restriction of the circuit ( seen from the fuel filter output) is formed by the fuel pressure regulator and the WUR . So during this testing the restriction is high and the resultant system fuel pressure is measured arround 6.8 bar (stock). It could be funny to measure the qty of fuel which is sent back to the tank during this testing ...at least there is 125ml/30sec by the WUR....by it design, the fuel pressure regulator send much more qty than the WUR.

Now if you are doing the same test, but with lower controle pressure (let's say 1.2 bar) and with metering plate moved at his maximum, since the fuel can escape through the chamber valves & injectors , the total restriction ( seen from the fuel supply ouput) becomes lower right ? Somewhere, the testing conditions becomes closer to the free flow testing testing right ? So the job becomes easier for the fuel supply system.

The fuel supply system is correctly working under high ( but so far not infinite) restriction. The same system provide the correct flow under 0 restriction . So how could it be possible that same system doesn't work correctly under intermediate restriction ??? Somewhere how could it be possible for the pump to do a bad job while the fuel has more opportunity to escape of the system and while the job become easier ???? ( and closer to free flow conditions ) .......
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Old 07-02-2009, 12:17 PM
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Originally Posted by Thierry25 View Post
Hello Keith

Sorry but what do you mean by shimmed level ? Do you mean with pressure regulator shimming ?
System Pressure with the pressure reg bumped up.

The factory pumps an support a lot of HP. The question is can they do so with a restriction that reqires around 100PSI or so.

Just like with EFI injectors, it you bump the fuel pressure, your can support more HP.
Old 07-02-2009, 03:16 PM
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Quote:
Originally Posted by Thierry25 View Post
Yes I thought in this way too ! That's true that the Porsche testing procedure is a free flow test. The fuel supply is disconnected of the head and we just measure the fuel qty which is provided at the output of the fuel system ( just right after the fuel filter )....so yes, the maximum fuel supply flow is measured during this procedure... since the total restriction ( seen from the filter output) is equal to 0 . No restrication = maximum flow ( and less current in the pump because easier job)

Now, you are agree that if we close the fuel supply output, the pressure will increase a lot ( maybe 11 bar) and the absorbed power by the pump will be at it maximum right ? ( It will probably die very quickly )
Yep, current demand will go up and heat will go up, reducing the pump life. But the
pump may stall completely before 11 bar is reached, or the internal bypass pressure limiter of the pump will open, depending upon the pump.

Quote:
Originally Posted by Thierry25 View Post
Now when we make the fuel system pressure testing as stated in the manual , everything is connected. Right ? So the fuel system pressure regulator is working and the WUR are connected ( warm pressure 4.5 bar) . Right ? Both of them do their job and there is a fuel flow which comes from fuel supply and which go back to the tank. right right ? There is absolutely no fuel which are going to injector since the metering plate is totally closed ? right ? As the lambda freq valve is off, there is no fuel flow which in this device right ? So the restriction of the circuit ( seen from the fuel filter output) is formed by the fuel pressure regulator and the WUR . So during this testing the restriction is high and the resultant system fuel pressure is measured arround 6.8 bar (stock). It could be funny to measure the qty of fuel which is sent back to the tank during this testing ...at least there is 125ml/30sec by the WUR....by it design, the fuel pressure regulator send much more qty than the WUR.
Yep, if there is no fuel coming from the injectors, then it all returns to the tank. That would be a good indicator of how well the system is performing by measuring the return flow at idle and max RPM.

Quote:
Originally Posted by Thierry25 View Post
Now if you are doing the same test, but with lower controle pressure (let's say 1.2 bar) and with metering plate moved at his maximum, since the fuel can escape through the chamber valves & injectors , the total restriction ( seen from the fuel supply ouput) becomes lower right ? Somewhere, the testing conditions becomes closer to the free flow testing testing right ? So the job becomes easier for the fuel supply system.
That's where it's tricky, the fuel pump is still being regulated by the primary pressure regulator to 6.8 bar, regardless of what the control pressure is, but it's now trying to maintain 6.8 bar while trying to supply the maximum volume of fuel through the plunger and barrel. The pump should never see a free flow condition, due to the primary pressure regulator.

Quote:
Originally Posted by Thierry25 View Post
The fuel supply system is correctly working under high ( but so far not infinite) restriction. The same system provide the correct flow under 0 restriction . So how could it be possible that same system doesn't work correctly under intermediate restriction ??? Somewhere how could it be possible for the pump to do a bad job while the fuel has more opportunity to escape of the system and while the job become easier ???? ( and closer to free flow conditions ) .......
With a proper designed fuel supply system the pump will never see less that the regulated 6.8 bar pressure, but it will have to deliver the volume required at both idle and max RPM. My guess, is your stock fuel pumps were falling off at the top. If it was measured, you may have seen the 6.8 bar drop to 5.8-6.0 bar. Your new 044 is probably holding the pressure through the full range. This is probably why shimming the fuel pressure regulator doesn't show much change in the high end AFR in some cases, it's seeing a big pressure drop because the fuel system can't keep up with the volume required.

When you look at the CIS system running 6.8 bar versus EFI running around 2.5 bar, you realize CIS needs better pumps, because they are required to deliver the same fuel volume, for the same amount of horsepower, at a higher pressure.

This brings up a question. The manual for my 1986 CIS shows a testing pressure of 6.7-7.4 bar, with adjusting pressure of 6.9-7.1 bar. So it seems reasonable that we could run 7.4 bar? Others have reported that shimming the primary pressure regulator higher didn't produce results, but I'm betting their fuel system couldn't hold the 7.4 bar all the way to the top? With proper pumps, and system pressure, there may be plenty of fuel for higher horsepower levels?
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Old 07-02-2009, 10:00 PM
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Quote:
Originally Posted by winrice View Post

...the fuel system can't keep up with the volume required.

When you look at the cis system running 6.8 bar versus efi running around 2.5 bar, you realize cis needs better pumps, because they are required to deliver the same fuel volume, for the same amount of horsepower, at a higher pressure.

This brings up a question. The manual for my 1986 cis shows a testing pressure of 6.7-7.4 bar, with adjusting pressure of 6.9-7.1 bar. So it seems reasonable that we could run 7.4 bar? Others have reported that shimming the primary pressure regulator higher didn't produce results, but i'm betting their fuel system couldn't hold the 7.4 bar all the way to the top? With proper pumps, and system pressure, there may be plenty of fuel for higher horsepower levels?

+1
Old 07-03-2009, 07:32 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #40 (permalink)
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