Imagine Auto Fuel Head Mod
10-11-2005, 07:53 PM
#61
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I don't have any extra fuel left over, I need every bit that gets pumped into my cylinders. ha ha.
Stephen will have to answer your questions. I really wish there was a fix for my stumbling and stuttering on a cold engine start. It idles just fine, but you can't accelereate without it barking at you.
Stephen will have to answer your questions. I really wish there was a fix for my stumbling and stuttering on a cold engine start. It idles just fine, but you can't accelereate without it barking at you.
10-11-2005, 10:11 PM
#62
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Originally Posted by nathanUK '81 930 G50
I have heard that excessive fuel will wash the oil lubing the cylinder bores and rings.
It will reduce torque/power
It will reduce torque/power
Yes, you won't get as much power as you would if you were running on the edge of lean but you also won't get any pre-detonation. Which is what kills engines.
10-12-2005, 03:32 AM
#63
"I really wish there was a fix for my stumbling and stuttering on a cold engine start. It idles just fine, but you can't accelereate without it barking at you."
I think this is a by product of this fix. You need extra fuel, but this way you cannot meter the amount of fuel when you need it. You get it when you want it and also when you don't. I would suspect the engine is rich and stumbles as the cols start function is active and now extra fuel is going in on the cold start due to the larger openings in the fuel head.
This is why I feel the CIS head mod is only half what you need. Now that you deliver more fuel, its important to control it based upon the engines need.
The new controller is working great. It has the ability to meter the fuel by controlling a frequency Valve, with a complete 3D fuel map RPM v MAP. Now the fuel volume can be controlled based upon the VE of the engine. I have had them include a 3D Ignition map which will retard the timing based upon RPM v MAP, so now as the boost is increased the fuelling can be adjusted and the Ignition can be retarded to suit. All functions are controlled and mapped with a PC just like an EFI system. Just to make the whole system complete, they have added electronic boost control, which controls boost as a function of engine speed. The boost can be programmed every 500 RPM, again just like an EFI system. I expect all testing to be complete in 2 weeks. Not sure what this will cost, but I have asked for it to be under $ 1000.00. If you consider what it costs to buy the Andial unit, which does not control the fuel based upon RPM or MAP, Ignition systems to control the Timing and a Electronic Boost controller, you could spend almost $ 1000.00 for each.
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I think this is a by product of this fix. You need extra fuel, but this way you cannot meter the amount of fuel when you need it. You get it when you want it and also when you don't. I would suspect the engine is rich and stumbles as the cols start function is active and now extra fuel is going in on the cold start due to the larger openings in the fuel head.
This is why I feel the CIS head mod is only half what you need. Now that you deliver more fuel, its important to control it based upon the engines need.
The new controller is working great. It has the ability to meter the fuel by controlling a frequency Valve, with a complete 3D fuel map RPM v MAP. Now the fuel volume can be controlled based upon the VE of the engine. I have had them include a 3D Ignition map which will retard the timing based upon RPM v MAP, so now as the boost is increased the fuelling can be adjusted and the Ignition can be retarded to suit. All functions are controlled and mapped with a PC just like an EFI system. Just to make the whole system complete, they have added electronic boost control, which controls boost as a function of engine speed. The boost can be programmed every 500 RPM, again just like an EFI system. I expect all testing to be complete in 2 weeks. Not sure what this will cost, but I have asked for it to be under $ 1000.00. If you consider what it costs to buy the Andial unit, which does not control the fuel based upon RPM or MAP, Ignition systems to control the Timing and a Electronic Boost controller, you could spend almost $ 1000.00 for each.
\]
10-12-2005, 10:45 AM
#65
Rennlist Lifetime Member
The issue with the colder starts is not the amount of fuel going in the system per say. The way we machine it and readjust the system at idle the system does not inject more fuel than normal. When we close up the lambda control port and reopen the differential port the systems sometimes will be slow to react when cold. This will cause a leaner mixture or a pulse at first. Once warm it isn't an issue. Normally the port that has been machined out will control this. Once it is gone some might experience this. It is a very fine line between more fuel and not running or running perfect start when cold and less fuel. Not all do it. It has a lot to do with the shape of the head when rebuild. Some heads are bad enough that we can't control the low end pulsing because it is too worn and control is not tight. Hence we always have cores to build good working units.
The issue with controlling the head via the system presented is the fuel head mod removes the external differential port control which in turn will eliminate the ability to piggy back the system and raise and lower pressures.
The issue with controlling the head via the system presented is the fuel head mod removes the external differential port control which in turn will eliminate the ability to piggy back the system and raise and lower pressures.
10-12-2005, 11:49 AM
#66
Rennlist Member
Thread Starter
Originally Posted by PorschePhD
The issue with the colder starts is not the amount of fuel going in the system per say. The way we machine it and readjust the system at idle the system does not inject more fuel than normal.
You guys currently have my fuel head and are going to be shipping it directly to my mechanic. Based on your comment above rearding readjusting the system at idle, should I expect my mechanic to be messing with idle or is this a pure plug and play application.
BTW... really like the HFS.
Thanks!
10-12-2005, 02:19 PM
#71
"The issue with controlling the head via the system presented is the fuel head mod removes the external differential port control which in turn will eliminate the ability to piggy back the system and raise and lower pressures"
Not sure what you mean here. I don't know enough about how it works to understand. 1 pressure is controlled by the relief and the other by the WUR. Remove the WUR control in a mechanical system and you must have 2 constant pressures, or am I wrong here?
Seems that the best of both worlds can be had here. Add fuel overall, then be able to control the amount as you need it across the engines VE Map. Now make a mod to your engine, and just re map the fuel pressure to suit the change. Simple and effective electronic control over the mechanical system. Otherwise, everything you do is hit or miss based upon the mechanicals of the engine. Maybe the issuses with the cold start etc could be eliminated.
Some need more fuel but need the ability to control it without changing over to full EFI.
Not sure what you mean here. I don't know enough about how it works to understand. 1 pressure is controlled by the relief and the other by the WUR. Remove the WUR control in a mechanical system and you must have 2 constant pressures, or am I wrong here?
Seems that the best of both worlds can be had here. Add fuel overall, then be able to control the amount as you need it across the engines VE Map. Now make a mod to your engine, and just re map the fuel pressure to suit the change. Simple and effective electronic control over the mechanical system. Otherwise, everything you do is hit or miss based upon the mechanicals of the engine. Maybe the issuses with the cold start etc could be eliminated.
Some need more fuel but need the ability to control it without changing over to full EFI.
10-15-2005, 12:31 AM
#73
Rennlist Member
I had a euro SC with the euro head and it was explained to me that the euro head had larger internal passages which were cast into the head, this allowed it to flow more fuel.
The core used to make the casting looks like a spiders legs. I am confused on how these passages can be enlarged to allow for additional fuel flow by machining. Wouldn't it make more sense to design an identical head and cast it with larger dia passages. One would be able to increase the passage side considerably if needed.
I was also told that the dia of the passages of the euro head were identical to the dia of the hole in the banjo bolts. If these holes are not enlarged wouldn't this also restrict the fuel flow?
The core used to make the casting looks like a spiders legs. I am confused on how these passages can be enlarged to allow for additional fuel flow by machining. Wouldn't it make more sense to design an identical head and cast it with larger dia passages. One would be able to increase the passage side considerably if needed.
I was also told that the dia of the passages of the euro head were identical to the dia of the hole in the banjo bolts. If these holes are not enlarged wouldn't this also restrict the fuel flow?
10-15-2005, 01:31 PM
#75
Rennlist Member
Sameer, I figured I wouldn't get a reply. 
Just coming from a foundry background and manufacturing very complicated castings for the past 23+ years I would think there would be a better approach at resolving the issue than modifying the fuel head. If restrictive passages are our biggest issue there are other ways around the problem. Why not just cast a fuel head with much larger passages and allow the fuel to flow through the head. Then again why didn't the factory revise the head after all those years? I don't think it was tooling costs. Maybe it had something to do with fuel economy? I have no idea but would be interested in a better mouse trap instead of modifying the old without the expense of EFI.
I am also interested in knowing why my mechanic feels the '94 turbo flows enough fuel to adequately handle at least 400 rwhp without the need for modifications yet others feel differently. Is it more an issue of obtaining more out of the car with the same modifications or is it more an issue of safety?
Just coming from a foundry background and manufacturing very complicated castings for the past 23+ years I would think there would be a better approach at resolving the issue than modifying the fuel head. If restrictive passages are our biggest issue there are other ways around the problem. Why not just cast a fuel head with much larger passages and allow the fuel to flow through the head. Then again why didn't the factory revise the head after all those years? I don't think it was tooling costs. Maybe it had something to do with fuel economy? I have no idea but would be interested in a better mouse trap instead of modifying the old without the expense of EFI. I am also interested in knowing why my mechanic feels the '94 turbo flows enough fuel to adequately handle at least 400 rwhp without the need for modifications yet others feel differently. Is it more an issue of obtaining more out of the car with the same modifications or is it more an issue of safety?