GTR Forum banner

41 - 60 of 111 Posts

·
Registered
Joined
·
2,056 Posts
keith said:
SteveN

All i can tell you is that we were running the 1000cc injectors with
just over 7 bar fuel pressure on full boost and the boost was 2.5 bar.

They ran out of duty big time we had to fit 1200cc

Keith
Increasing fuel pressure over a certain point doesn't actually win you anything because the injector can't open as quickly because it has to fight against the fuel pressure.

I don't know what that point is, I don't profess to be an expert on the subject, I don't claim to have the knowledge of someone like Rod Bell but IMHO it is nevertheless a point worth raising as 7 bar seems quite high to me.

If you want good atomisation why not go for 2 sets of 600s?
 

·
Registered
Joined
·
2,949 Posts
Discussion Starter #42 (Edited)
kingsley said:
Increasing fuel pressure over a certain point doesn't actually win you anything because the injector can't open as quickly because it has to fight against the fuel pressure.

I don't know what that point is, I don't profess to be an expert on the subject, I don't claim to have the knowledge of someone like Rod Bell but IMHO it is nevertheless a point worth raising as 7 bar seems quite high to me.

If you want good atomisation why not go for 2 sets of 600s?

Hi Kingsley

When I imported my car it had 1000cc injectors and was running 2 bar boost with about 5.4 bar fuel pressure on boost,the injectors were up to the job no problem.then R.B Motorsport built the new engine with big cams and a pair of 3037s turbos and a load of head work,when we went to map the car again we got to around 1.6 bar boost and run out of injector.to overcome this on the day we then had to crank up the fuel pressure so we could map the car,but they were still not big enough so we had no option but
change them for a set of 1200cc injectors.

Now this is the point that I am trying to make,my car did not have over 1000 bhp we will never know for sure because it will never be run on a dyno we could not run no more fuel pressure,the exhaust gas temps were as high as we wanted to run,it is common knowledge that the Japs like to run there car's on the rich side.

So how can they make 1200 ps/bhp on 1000cc injectors ????:rolleyes:

Keith
 

·
Registered
Joined
·
2,056 Posts
Hi Keith,

In my previous post I think I should have added that I don't actually disagree with anything you have said ... :)

Unless the Jap tuners have found some mysterious way of getting more power from the same amount of fuel, I too don't see how they're going to get 1200bhp from 1000cc injectors. There are ways of cutting internal losses etc but I wouldn't expect THAT much difference ...
 

·
Registered
Joined
·
2,949 Posts
Discussion Starter #44
kingsley said:
Hi Keith,

In my previous post I think I should have added that I don't actually disagree with anything you have said ... :)

Unless the Jap tuners have found some mysterious way of getting more power from the same amount of fuel, I too don't see how they're going to get 1200bhp from 1000cc injectors. There are ways of cutting internal losses etc but I wouldn't expect THAT much difference ...

Hi kingsley

I just cant see it myself:rolleyes: the fuel that we can get our hands on
here in the UK would be loads better anyway.

I see that the Veilside R32 runs on 1800cc injectors,that more like it

Keith
 

·
Registered
Joined
·
3,047 Posts
Cars

What cars claim 1200 bhp with 1000cc injectors Keith?

When we run my R34 on full boost it was using 100% IDC.

From memory if we needed any more I think we would have had to go bigger on the injectors, but we never did as the turbos were all blown out too.

There are still 1000cc's in the car now but its only running 1.2bar and it seems happy to do it after Mr Ito tuned it for me.

We'll be running 1000cc's again for the Drag GTR to start with as it only has a T51.
 

·
Registered
Joined
·
1,362 Posts
kingsley said:
Increasing fuel pressure over a certain point doesn't actually win you anything because the injector can't open as quickly because it has to fight against the fuel pressure.

I don't know what that point is, I don't profess to be an expert on the subject, I don't claim to have the knowledge of someone like Rod Bell but IMHO it is nevertheless a point worth raising as 7 bar seems quite high to me.

If you want good atomisation why not go for 2 sets of 600s?
Not necessarily true, its very dependant on the quality of the injector.

F1 cars run circa 10 bar of fuel pressure, and have exceedingly quick duty cycles due to how high they rev.

1000cc injectors & 1000bhp - its doable IMO & would work. Wouldn't be cheap though.
 

·
Registered
Joined
·
1,883 Posts
SteveN said:
Asim- Spot on.

Exactly the reason turbo cars run a rising rate regulator :)
Yeah.... thats what i have always used when calculating injectors.

So if keith is running with 1000cc injectors, and 4.5bar effective pressure... and the injectors are not 110& calibrated... AND running a safe/ rich map... then it will not produce 1000hp....

Could it be as simple as that?? :)

Please do not misunderstand this.. im not an expert.... just like to learn things this way ;)
 

·
Registered
Joined
·
2,110 Posts
I'm also interested to know which Japanese tuners claim to run 1200ps on 1000cc injectors? Unless of course they are also applying the fantasy hp at the wheels to hp at the flywheel conversions that have been provided on the board in prior posts. Its amazing what you can achieve with those numbers. :D

Cya O!
 

·
Registered
Joined
·
2,949 Posts
Discussion Starter #51
hipogtr said:
I'm also interested to know which Japanese tuners claim to run 1200ps on 1000cc injectors? Unless of course they are also applying the fantasy hp at the wheels to hp at the flywheel conversions that have been provided on the board in prior posts. Its amazing what you can achieve with those numbers. :D

Cya O!
Hi hipogtr

I am not naming names as I will be strung up again for it.;)

Keith:smokin:
 

·
Registered
Joined
·
1,969 Posts
Asim R32GTR said:
If you have 2.5bar boost in the plenum, and the fuelpressure is 7bar... isnt the effective fuelpressure then 4.5bar??
Not exactly, when injecting a liquid into a gas, you do not have to raise liquid pressure at a ratio of 1:1.
And in the case of injectors, that only open during intake stroke, pointing downstream, you'd be injecting into a much lower air pressure than the plenum boost pressure, anyway. Although I guess not many have big enough injectors to complete fuel delivery within the intake stroke.:D
 

·
Registered
Joined
·
568 Posts
A few thoughts

Turbo cars do not as a rule have "rising rate" regulators, they have regulators that reference manifold pressure. A rising rate regulator will increase the fuel pressure at an increaseing rate with manifold pressure. So where a conventional regulator will increase the fuel pressure (at the injector) by the same amount the manifold pressure increases, a rising rate regulator will increase the fuel pressure by more than the manifold pressure increase.

Fuel injectors do not only inject on the intake stroke. Most conventional cars inject when the inlet valve is actually closed. This does 2 things, it keeps the valve temperature down, and heats the fuel or even atomises it before it is sucked/blown into the cylinder. Trying to inject while the valve is open usually results in more power, but it's very difficult to do both, as there will be a crossover point at which the engine runs rather rough at moderate load. To acheive 100% IDC (relative to 360deg of crank rotation)

Fuel pressure should be quoted as measured/compared as a differential pressure. Just as Asim points out. If the fuel was at 5 bar (gauge pressure) but the manifold pressure was 6 bar, air would flow into the fuel system (right before engine blows up!).

Some engines are more efficient others. I know of some Subaru engines run on an ENGINE dyno with 740cc injectors that have made over 550hp with pump fuel plus octane booster. We also know (from ASNU testing) that these paticular injectors will flow more with increased fuel pressure, up to 4.5 bar at least. I don't see why six 1000cc injectors can't easily make a genuine 1000hp at the crank. Of course you need the pumps to back it up, which would be at least 2 bosch 044 pumps to be sure. If you looked closely at some subarus at TOTB last year, you would have seen fuel coolers on two of them, not without reason. Increasing fuel temperature is a serious issue when you are pumping the heat from up to 4 fuel pumps into it, and some heat picked up from the fuel rail itself, you could be looking at more than 500W of heating! Fuel temperature will affect AFR.

Cheers

Paul
 
Joined
·
3,663 Posts
Some engines are more efficient others. I know of some Subaru engines run on an ENGINE dyno with 740cc injectors that have made over 550hp with pump fuel plus octane booster. We also know (from ASNU testing) that these paticular injectors will flow more with increased fuel pressure, up to 4.5 bar at least. I don't see why six 1000cc injectors can't easily make a genuine 1000hp at the crank. Of course you need the pumps to back it up, which would be at least 2 bosch 044 pumps to be sure. If you looked closely at some subarus at TOTB last year, you would have seen fuel coolers on two of them, not without reason. Increasing fuel temperature is a serious issue when you are pumping the heat from up to 4 fuel pumps into it, and some heat picked up from the fuel rail itself, you could be looking at more than 500W of heating! Fuel temperature will affect AFRTE
Someone else that has done his on homework.

cheers for the data. The ASNU machines are awesome arent they?

Markie mark
 

·
Registered
Joined
·
2,201 Posts
Two walboro fuel pumps (255lph) feeding a swirl pot, feeding two bosch 044 pumps, feeding 6 1000cc injectors will supply enough fuel for 1000hp atf.
Dyno dynamics rollers 1027hp.

IMO 5.5cc of fuel is needed for each hp, of course this will change depending on each cars charcteristics/mapping etc..... 100%IDC (not suggesting you should go that high) on 1000cc injectors is 1090hp.

On an ASNU machine i tested my old 720c injectors (denso/trust), at 3bar they flowed 700cc of fuel, at 3.5bar they flowed 800cc, at 4bar they flowed 880cc, at 4.5bar they flowed 960cc and at 5bar they flowed 1030cc (diferential pressure/fully open).

You would have to run 7.5bar absolute fuel pressure at 2.5bar boost to get 1030, not sure many pumps would like that :D

My point is though, what would the 1000cc inj flow at different fuel press...? anyone tested some?

Rob
 

·
Registered
Joined
·
2,056 Posts
-C- said:
Not necessarily true, its very dependant on the quality of the injector.

F1 cars run circa 10 bar of fuel pressure, and have exceedingly quick duty cycles due to how high they rev.
Just because F1 injectors run 10 bar doesn't mean that higher fuel pressures make it harder for injectors to open quickly. F1 injectors are clearly designed to work with higher fuel pressures and as such cope well with it but I doubt they'd do so well at 50 bar.

As I said in my earlier post, I don't know where the limits are, and I suspect that it will vary from one injector to the next (and possibly depends on the current supplying ability of the driving circuits too, though I don't know how much of a limitation this is in reality). However, there will be limits.

My comment was intended more as food for thought rather than a definitive "this won't run well at 7 bar" statement.

Most injectors aren't designed to run at F1 fuel pressures and as such probably won't have the ability to ... or at least not particularly well.
 

·
Registered
Joined
·
2,056 Posts
Rob, very interesting figures there.

I always thought that at best, an increase of fuel pressure by a factor of n gives an increase of flow by the square root of n. However, the figures you quoted there exceed that. Any idea why?

eg
"at 3bar they flowed 700cc of fuel, at 3.5bar they flowed 800cc"

3 bar -> 3.5 bar is ratio of 1.6666
take the square root of this = 1.0801
multiply this by 700 to get theroetical flow at 3.5 bar = 756cc

yet you've got 800

I'm not doubting your figures, I'm hoping for an explanation :)

Maybe I've been using the wrong formula all these years :rolleyes: ??
 
Joined
·
3,663 Posts
Tweenierob,

I get nearly as excited seeing a ASNU machine as using a DYNAPACK dyno , both pieces of equipment all tuning shops should have In my opinon.

Mark
 

·
Registered
Joined
·
160 Posts
I used 6x 1000cc on my last setup and they was running at 90% with 840hk/952Nm at the wheels.

I think I have read about some EVO`s that are running 4x 1000cc and are claiming 900hk++.. But that includes 275hk drive tain loss hehehe
 
41 - 60 of 111 Posts
Top