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  #16  
Old 11-05-2009, 12:46 PM
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I was torn between the D-jet conversion you were doing and going the fuel rail route. I decided on the fuel rail since the Ford injectors cost me $20 for all eight from a pic'n'pull, they are much more readily accessible and I don't have to pull the manifold. The stock air filter is retained and I am leery of the Djet's barbed hose fittings.

The M117ed powered W114 is definitely in my mind. Should other problems crop up with the W126 then it may well be the future powerplant for my project car.

Let's see, then I could pull the M115 from the wife's 250C, slip in the M110, pop the throttle body set-up on the M110, since her car is already MS'ed, of course then, I'd need to come up with a M110 flywheel, no big deal, I know where there is a W108 with a M129 manul trans, pull that apart, have the flywheel mated to the M110...

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  #17  
Old 11-06-2009, 12:15 AM
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Sounds interesting! I'm converting my '73 280S from auto to manual, I have all the bits for conversion except the flywheel. M129 flywheel is the same as M110 flywheel in terms of weight? I found a M130 manual engine in a shop and I'm trying to ask the shop owner to sell me that flywheel. Someone told me that M110 flywheel weighs 18lbs, I'm weighing the M130 flywheel if the owner permits me.
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  #18  
Old 11-22-2009, 01:50 PM
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Question for those converting D-Jet to Megasquirt:

What fuel pressure will you run at? Are you using the original D-Jet pumps?

Reason I ask, is that original D-Jet rail and hoses ran at 28.4 psig. At that pressure they are prone to vapor locking when using winter fuels. More flow might help cool the fuel as might a fuel cooler. But, that would need a different pump.
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  #19  
Old 11-22-2009, 02:37 PM
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That's an interesting question which brings two more: should the pressure be vacuum actuated, and can the stock injectors be kept if ran at a higher pressure?

It appears that a vacuum actuated fuel pressure regulator enables an easier tunig, and is the way to go according to the Megasquirt forum. I got a vacuum actuated FPR out of a VW Vanagon. I measured it and it delivers 30 psi at idle and 40 psi at higher revs.

The 4.5 blue injectors have a too big flow rate, especially if ran at a higher pressure, leading to tuning problems at idle. The 3.5 yellow injectors are hard to find and expensive. So I'm getting some Nissan 280Z turbo injectors. They are 260 cc and are a straight replacement. They are easy to get.

My Djet fuel pump delivers over 50 psi so I am planning to keep it unless it cannot deliver at least 45 psi at full throttle and 6000 rpm.
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  #20  
Old 11-22-2009, 06:02 PM
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Quote:
Originally Posted by GGR View Post
That's an interesting question which brings two more: should the pressure be vacuum actuated, and can the stock injectors be kept if ran at a higher pressure?

It appears that a vacuum actuated fuel pressure regulator enables an easier tunig, and is the way to go according to the Megasquirt forum. I got a vacuum actuated FPR out of a VW Vanagon. I measured it and it delivers 30 psi at idle and 40 psi at higher revs.

The 4.5 blue injectors have a too big flow rate, especially if ran at a higher pressure, leading to tuning problems at idle. The 3.5 yellow injectors are hard to find and expensive. So I'm getting some Nissan 280Z turbo injectors. They are 260 cc and are a straight replacement. They are easy to get.

My Djet fuel pump delivers over 50 psi so I am planning to keep it unless it cannot deliver at least 45 psi at full throttle and 6000 rpm.
Gael - The D-jet pumps can deliver higher pressure, but the flow rate can be the problem. I think I read that the dead head pressure is about 60 psig.

MB specify a minimum flow of 2L/min for the fuel flow on a D-Jet. At the moment my old pump is only putting out about 1.7-1.8 l/min with engine off (no flow to injectors). You would think that would be enough, but MB says to replace pump if you can't get 2L/min.

I am staying with the D-jet for now, but am thinking about installing a higher capacity pump. The D-jet doesn't support a FPR with vacuum input but I guess many later cars had that.

Seems that reason that good flow back to tank is needed, is to keep fuel temperature down to stop vapor locking. If you can run at 45 psig, vapor locking should be less of a problem. These days, it's only a problem with winter fuel because in summer environmental laws have pushed the RVP (volatility) of fuel down.

BTW - I am interested in learning more about those Nissan injectors. I also heard that the fuel pump off the 280Z can be used but need to find out the specs.
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  #21  
Old 11-22-2009, 07:06 PM
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These Nissan 280Z turbo orignal equipment injectors I got look exactly like the Bosch of the 4.5 but they have a brown top instead of a blue one. The ones I got are marked "JEGS" on them. I guess this is the brand. They are not Bosch. They are low impedence abd deliver 260cc/min at 43.5 psi.

On another note I came accross an EFI system called VEMS. It can do full sequential fuel and spark, had a lot of stuff integrated that needs to be purchased aside with MS (knock sensor, WBO2...) and works with Megatune. It's not that much expensive once added the cost of the side stuff needed with MS. You should have a look at it. I will be curious to know what you think.
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  #22  
Old 11-22-2009, 10:30 PM
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Quote:
Originally Posted by GGR View Post
These Nissan 280Z turbo orignal equipment injectors I got look exactly like the Bosch of the 4.5 but they have a brown top instead of a blue one. The ones I got are marked "JEGS" on them. I guess this is the brand. They are not Bosch. They are low impedence abd deliver 260cc/min at 43.5 psi.

On another note I came accross an EFI system called VEMS. It can do full sequential fuel and spark, had a lot of stuff integrated that needs to be purchased aside with MS (knock sensor, WBO2...) and works with Megatune. It's not that much expensive once added the cost of the side stuff needed with MS. You should have a look at it. I will be curious to know what you think.
Had a quick look at VEMS - Too much to absorb, but I guess there are several companies packaging engine management systems. Don't see any Mercedes mentioned on that site. For my old car, all I really need is a better way of controlling the FI system as parts like the trigger points and MPS wear out.

I looked at this one a while back : http://sdsefi.com/specific.html - For a car like my SL, maybe using the basic kit is all that would be needed? It's just over $1000, but a D-Jet system would need to add a TPS, a MAP sensor. Not sure what else to just duplicate the D-Jet FI system.

BTW - It worth checking through the links at the bottom of the home page - there's a lot of info on conversions in general as well as sources for some parts.
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Last edited by Graham; 11-22-2009 at 11:14 PM.
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  #23  
Old 11-23-2009, 07:01 PM
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If I cant get the d-jet m110, I will convert my 280S into TBI set-up, same as Gerardo does, does a TBI make the same power as Multi-Port Injection given the same displacement?
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  #24  
Old 11-24-2009, 08:56 AM
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No. TBI will not give you a "power" increase comparable to multi-port. It is head and shoulders above the carburetor as the ECU can monitor and adjust the mixture "on the fly".

TBI is essentially just an electronically controlled carburetor. It still requires the fuel to be mixed into the intake air flow by "swirling" and is dependent on the smooth flow of air.

Multi-port is injecting the atomized fuel directly into the individual cylinders and only uses the intake piping as air supply. No "swirling" needed for the mixture and "instant on" application of fuel increases.

Differences?
TBI runs at 13-20 PSI fuel pressure and is mainly for smoother power, reliability, emissions control and matches up better/easier with an existing design carbureted intake set-up.

Multi-port will give you more power, instant "snap" response, greater control of the burn but you trade off with higher fuel requirements (40-60 PSI and a much larger required fuel flow volume), complexity of the system ,1 or 2 injectors on the TBI vs. however many cylinders you have on the muti-port.

To do a multi-port properly you need to use the fuel injected heads but you can machine an existing intake manifold to accept the injectors with very good results.

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