EFI for TR5/6?

[JochemsTR]

I rebuild using CP Bodies. For the fuelrail, I build them myself. Some customers like the extruded aluminium version, but that is not my favorit.

Bodies are machined, bearings installed and modified to assume MAP. I keep the original throttle discs since they have the best fit. The aftermarket ones are sh%$§&t! I like the original PI look.

Single TB? That would work also. Both systems have their Pros and Cons.

What is the recommendation? ..... recommend a BMW to a Mercedes driver and vice versa......no chance.

In my opinion, for the "normal" EFI driver, you will not recognize the difference. especially when your engine is not overly tuned.

Edited December 15, 2022 by JochemsTR

[Richard71]

Hi Jochems,

Do you provide a service for the throttle body conversion?

Richard.

[mtrehy]

20 hours ago, CK's TR6 said:

It is also the response coming off idle. You are stopped at the light and just need a few hundred RPM as you let the clutch out, imagine that a slight tip in of the throttle is a big change because the single TB lets in a lot of air. Makes daily driving a challenge.

nonsense. unless you've completely miss-sized the throttle body it will be absolutely fine. People have been doing this for 20+ years and yet is keeps coming up as some kind of new advance in TR6 modification every 6 months on here

[mtrehy]

15 hours ago, JochemsTR said:

I rebuild using CP Bodies. For the fuelrail, I build them myself. Some customers like the extruded aluminium version, but that is not my favorit.

Bodies are machined, bearings installed and modified to assume MAP. I keep the original throttle discs since they have the best fit. The aftermarket ones are sh%$§&t! I like the original PI look.

Single TB? That would work also. Both systems have their Pros and Cons.

What is the recommendation? ..... recommend a BMW to a Mercedes driver and vice versa......no chance.

In my opinion, for the "normal" EFI driver, you will not recognize the difference. especially when your engine is not overly tuned.

 

 

 

100% correct. I'd add that single TB is going to be significantly cheaper so if you are paying someone else to do this for you then you need a pretty compelling reason to want ITB

[CK's TR6]

3 hours ago, mtrehy said:

nonsense. unless you've completely miss-sized the throttle body it will be absolutely fine. People have been doing this for 20+ years and yet is keeps coming up as some kind of new advance in TR6 modification every 6 months on here

mmmmm. According to my measurements my single throttle body has an inlet of 76mm and a bore of 72 mm.  That bore will support  700 cfm airflow. What does a TR6 engine flow at 6000 RPM? depends on VE. But, I don't think the VE is that great, even with head work, large valves, 1.55 rollers (a valve lift of 0.454"), a 275 duration etc etc. Maybe 80% VE. At that, maybe around 280 CFM, possibly 300.  However, at tip in, half my throttle plate opening is blanked off like I said. At WOT 6000rpm, I think my single TB is sized pretty good (the MAP has maybe 1-2 HPa loss from atmospheric). Did I completely miss-size my TB? What would be my tip in if it didn't have the blanking plate? Is it possible to have a single TB that will flow more than needed but still have good tip in? Is there any performance loss using a single TB that can flow this well at WOT compared to 6 ITB's? How is my tip in? How is my throttle response after 1/4 throttle application? I have read in many many places about the trouble with tip in and large single TB's. My statement was a caution regarding tip in and TB size. Is that nonsense? Only if the TB is miss sized according to your statement. Therefore, perhaps you can give guidance on what would be the proper sizing to avoid issues with tip in.

According to Motor Trend, 

"Back in the early days of the 5.0L Mustang, we marveled at the ability to upgrade to a 65mm throttle body. Modern motors are equipped with 90mm and dual 75mm throttle bodies right from the factory. Contrary to popular belief, a larger throttle opening does not reduce low-speed power, but the effect on throttle response can be dramatic. The reason is that (compared to a smaller throttle body), any throttle position will offer a sizable increase in airflow. Opening a 90mm throttle body even 3-5 percent is like opening a smaller throttle body 10-12 percent. This makes part-throttle driving difficult as minor throttle angle changes result in dramatic power differences."

[JochemsTR]

19 hours ago, Richard71 said:

Hi Jochems,

Do you provide a service for the throttle body conversion?

Richard.

Hi Richard, yes, but shipping from UK and back will add significant to the overall cost. As Matt notes, Single TB may be the cheaper way to go.

For further questions, please PN.

Regards

Jochem

[john.r.davies]

Changing the subject slightly, but any comments on the latest F1 engines?   Direct injection, of course, but a 500 bar - 7000psi!    Instant ignition, surely on meeting oxygen, so no spark plugs?

[unclepete]

What about positioning the Fuel Pressure Regulator?

I have been looking at the Returnless or Dead Head injection setup and it would seem a simpler method and only require a single fuel pipe to the engine bay?

[FatJon]

28 minutes ago, unclepete said:

What about positioning the Fuel Pressure Regulator?

I have been looking at the Returnless or Dead Head injection setup and it would seem a simpler method and only require a single fuel pipe to the engine bay?

Don’t do it. Hot fuel sat in a fuel rail in a traffic jam with no circulation. It overheats the fuel which vaporises, the engine goes lean and bad stuff happens. It’s a bodge to far just to save 2.5m of return hose.  Even the old Lucas at least had a small bleed back from MU to tank. 

[mtrehy]

19 hours ago, CK's TR6 said:

mmmmm. According to my measurements my single throttle body has an inlet of 76mm and a bore of 72 mm.  That bore will support  700 cfm airflow. What does a TR6 engine flow at 6000 RPM? depends on VE. But, I don't think the VE is that great, even with head work, large valves, 1.55 rollers (a valve lift of 0.454"), a 275 duration etc etc. Maybe 80% VE. At that, maybe around 280 CFM, possibly 300.  However, at tip in, half my throttle plate opening is blanked off like I said. At WOT 6000rpm, I think my single TB is sized pretty good (the MAP has maybe 1-2 HPa loss from atmospheric). Did I completely miss-size my TB? What would be my tip in if it didn't have the blanking plate? Is it possible to have a single TB that will flow more than needed but still have good tip in? Is there any performance loss using a single TB that can flow this well at WOT compared to 6 ITB's? How is my tip in? How is my throttle response after 1/4 throttle application? I have read in many many places about the trouble with tip in and large single TB's. My statement was a caution regarding tip in and TB size. Is that nonsense? Only if the TB is miss sized according to your statement. Therefore, perhaps you can give guidance on what would be the proper sizing to avoid issues with tip in.

According to Motor Trend, 

"Back in the early days of the 5.0L Mustang, we marveled at the ability to upgrade to a 65mm throttle body. Modern motors are equipped with 90mm and dual 75mm throttle bodies right from the factory. Contrary to popular belief, a larger throttle opening does not reduce low-speed power, but the effect on throttle response can be dramatic. The reason is that (compared to a smaller throttle body), any throttle position will offer a sizable increase in airflow. Opening a 90mm throttle body even 3-5 percent is like opening a smaller throttle body 10-12 percent. This makes part-throttle driving difficult as minor throttle angle changes result in dramatic power differences."

Not done one for a few years now, last couple I did I used 1247594, can't remember measurements. No drivability issues, like the dozens of other people on here using a single TB sourced from similar output applications without any issues. To be honest it seems like you are the only one having problems so it's likely the issue is something else you've got wrong with your install or mapping. 

[CK's TR6]

Did I ever state I had problems? Did I ever state what my tip in response was like? And, keep in mind my throttle body came from a 4.3L application. All I stated was, if you size a throttle body to have no restriction (that would imply it flows 1.7 times the actual CFM at that RPM) of flow at WOT and redline, which can conceivably may go to 7000 rpm, you may have driveability issues in day to day driving. And your response was, that is nonsense. Okay, it is nonsense. However, at WOT and 5500 RPM, my MAP is within 1% of atmospheric pressure, ie no restriction. I believe that my sizing wouldn't have any restriction even at 7000 RPM. Second, once past initial tip in, it doesn't take much to really flow a lot. So, no real loss in performance there either, even though it is a single TB. Speaking of tip in, I have no tip in issues at all, whatever assumptions you made to the contrary. I contend that is because of the design of the throttle plate as previously mentioned. If you want a list of references concerning tip in, I can give you a list.

On another topic, re fuel system design. Around here, fuel systems run from 3 to 6 bar fuel pressure. Mine is 3 bar. And it is a circuit design, which had heat sleeves etc through the T shirt area etc. In the summer, the fuel rail would get so hot you couldn't touch it, hotter than even the intake manifold. Never had any percolation problem or it going lean. This is in traffic with outside air temps around 115 F. However, I felt that I could partially cure this problem. I ran a teflon cored SS braided line from the back inside the trunk, down the inside of the B post, into the inside of the rocker, exit, then across the outer frame rail to the inner frame rail, then forward. Steel sleeves for most of it. Fuel rail doesn't get hot anymore. It runs cooler than the intake manifold, it has heat blocking stand offs. And my plenum has heat blocks between it and the initial 6 pipes, just like a carb car. And I have a custom heat shield that shields all this from the header. 

[unclepete]

6 hours ago, FatJon said:

Don’t do it. Hot fuel sat in a fuel rail in a traffic jam with no circulation. It overheats the fuel which vaporises, the engine goes lean and bad stuff happens. It’s a bodge to far just to save 2.5m of return hose.  Even the old Lucas at least had a small bleed back from MU to tank. 

Hi FatJon

Would the above apply with a pressure controlled pump (Variable Speed) with a pressure sensor on the fuel rail?

[FatJon]

Yes. At idle, or engine off after a run you still have a fuel rail right above the stinking hot exhaust manifold which is full of overheating fuel with no return flow keeping it cool. It’s a very bad idea which I have even seen on some expensive TR6 aftermarket EFI kits. For EFI the fuel rail is (almost) always pressure referenced to the manifold vacuum such that the differential pressure across the injector is always the same. The excess fuel returns to the tank so the rail is always full of cool fuel. 

[unclepete]

3 minutes ago, FatJon said:

For EFI the fuel rail is (almost) always pressure referenced to the manifold vacuum such that the differential pressure across the injector is always the same.

Good point!

I have seen on some 'Customer photographs' the MAP sensors located in the inlet plenum just after the Throttle Body. This is nowhere near the injectors and I would have thought the Inlet manifold adjacent to the injectors would have a far higher suction pressure, or is this not so important?

[FatJon]

1 hour ago, unclepete said:

Good point!

I have seen on some 'Customer photographs' the MAP sensors located in the inlet plenum just after the Throttle Body. This is nowhere near the injectors and I would have thought the Inlet manifold adjacent to the injectors would have a far higher suction pressure, or is this not so important?

Usually there are 2 map sensors. One in the plenum to measure atmospheric and one in the manifold. That way you don’t go rich at high altitude. The one in the manifold is the primary one for fuelling calculations, the other just adds the correction for atmospheric pressure. In some systems the manifold one is not present and a throttle angle sensor is used for fuelling calculations. That is quite common when using a throttle plate per cylinder where manifold vacuum is not a reliable indicator of fuel requirements.

[CK's TR6]

https://www.underhoodservice.com/point-of-no-return-returnless-fuel-injection-systems/

[FatJon]

2 hours ago, CK's TR6 said:

https://www.underhoodservice.com/point-of-no-return-returnless-fuel-injection-systems/

“Returnless EFI systems typically operate at a higher pressure than return-type systems. This is necessary to reduce the risk of fuel boiling and vapor lock in the injector supply rail during hot weather (since there is no recirculation of fuel from the engine back to the tank to keep the fuel supply rail cool). Because of this, a returnless EFI system may not perform well if fuel pressure or flow is less than specifications.”

 

 

 

 

[CK's TR6]

Some further quotes from same article:

"Returnless systems are now used on many late-model cars and trucks. The first ones appeared back in 1993 on certain Chrysler V6 and V8 truck engines. By 1998, all Chrysler cars and light trucks had them. In 1996, Toyota introduced its first returnless system, and Honda went returnless in 2001. General Motors and Ford started down the returnless route in 1999, and in 2004, GM went returnless on most of its full-size pickup trucks and SUVs with the Vortec 6000 (LQ4 and LQ9) engines, including the Cadillac Escalade; Chevy Silverado, Suburban and Tahoe; the GMC Sierra and Yukon; and Hummer H2.

Actually, there are two different types of returnless EFI systems in use: mechanical and electronic. In the mechanical systems, a mechanical regulator is mounted on the fuel pump module to provide a more or less constant fuel pressure to the engine. This type of setup works well with a speed-density EFI system that uses throttle position, intake manifold pressure and engine rpm to determine engine load rather than an airflow sensor.

On 1996 Chrysler and Dodge minivans with returnless EFI, the regulator can be serviced by removing the fuel pump module from the fuel tank, then prying back the locking tabs that hold the regulator in its housing. The regulator can then be pried out and replaced with a new one. There are also two O-rings inside the housing that also should be replaced. Forget these, and the system may not hold normal pressure."

According to RockAuto, the 96 Chryler minivan fuel pump operates at 49 PSI.  Here in Phoenix we have stop and go traffic approaching L.A. standards, add in the ambient temp of 115 F and all these idling cars in the summer, the roadway temps are probably very very high. I would think the cramped engine compartments are very high, but I don't see cars suffering from vapor lock in their MPFI systems.  If it was such a problem, there would be cars on the side of the road all the time in the summer but there isn't. Further quote:

"On a 2005 Chevy Silverado, for example, the on demand returnless EFI system has a turbine-style fuel pump inside the fuel tank that routes fuel through an in-tank filter to the in-tank regulator. The regulator maintains a preset pressure to the fuel injection system, which is 55 to 62 psi (or 48 to 54 psi on engine VIN code Z)"

So, it seems that a 4 bar system wouldn't have a problem. I did run my system at 4 bar after initial set up as the injectors were too small. I ran this way until I got bigger injectors.  

[unclepete]

20 hours ago, FatJon said:

In some systems the manifold one is not present and a throttle angle sensor is used for fuelling calculations. That is quite common when using a throttle plate per cylinder where manifold vacuum is not a reliable indicator of fuel requirements.

That whole article is interesting but it also raises as many questions as it answers.

If I am reading this right, the fuel pressure is regulated electronically by an algorithm within the throttle position signal? I would suppose that the inlet manifold vacuum pressure at the injectors can be physically measured or calculated and a graph drawn within the software of the ECU to match the lowering in manifold pressure (vacuum) relative to rises in RPM? Simples!!!

Is there an aftermarket ECU on the market that handles this?

[FatJon]

4 hours ago, unclepete said:

That whole article is interesting but it also raises as many questions as it answers.

If I am reading this right, the fuel pressure is regulated electronically by an algorithm within the throttle position signal? I would suppose that the inlet manifold vacuum pressure at the injectors can be physically measured or calculated and a graph drawn within the software of the ECU to match the lowering in manifold pressure (vacuum) relative to rises in RPM? Simples!!!

Is there an aftermarket ECU on the market that handles this?

I use MS3 Pro. 

https://www.diyautotune.com/product/ms3pro-evo-standalone-engine-management-system/

It’s overkill for a TR6 but there are cheaper versions with much the same functions but less inputs and outputs. I prefer the pro version as it’s got better chunky waterproof connectors. On mine the fuel pressure reg is connected to the inlet manifold so the fuel pressure tracks the manifold vacuum such that the pressure is always 3 bar above the manifold. You then map injector open time against rpm and either throttle angle or manifold pressure, or a hybrid of both in my setup. The hybrid mode works well with individual throttle bodies. It uses manifold pressure at small throttle openings and throttle angle at larger openings. That way you can use idle speed control which is not possible if you’re using pure throttle angle. The reason being that when the idle valve admits more air the throttle angle doesn’t change but the vacuum does.

 

[CK's TR6]

It appears that this whole idea of returnless EFI fuel system is more a US thing. Probably because the tuner market here follows the OEM technology. Just googling around I found two aftermarket PWM controllers for fuel pumps and that both Holley and Eldebrock have returnless systems. My neighbor is a Holley dealer and has been granted full access to the software (not the first time of having access to IP software). He has been doing EFI in big HP V-8 motors for several decades. He even sold EFI parts to GM as a OEM supplier.  If I get the opportunity to talk to him about it I will.  

[jr2]

2 hours ago, CK's TR6 said:

It appears that this whole idea of returnless EFI fuel system is more a US thing

It's global.  It was phased in shortly after the introduction of thermoplastic intake manifolds.

[CK's TR6]

I didn't know this but in the aforementioned Megasquirt 3 manual (Murray 2018), Page 139-140 detail PWM fuel pump control, talks about GM systems, pressure regulation,/correction, fuel rail pressure settings, etc etc.  I would assume then a MS3x can do the returnless PWM fuel pump control.

[JochemsTR]

17 hours ago, unclepete said:

Is there an aftermarket ECU on the market that handles this?

ecumaster

[JochemsTR]

There you go.

The components are readily available. big advantage, since there is no return line, and no circulation back to the fuel tank, therefore, no heating of the fuel in the tank and no increase in fuel vapor pressure. The biggest issue with a returnless system is the monitoring of the fuel pressure and keeping it controlled. Since running on min. 4 Bar, you need EV14 injectors rated 160 ml/min.

 

 

Edited December 19, 2022 by JochemsTR