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Webcon Retroject 38/38 TBI


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I know that there was a member who did an epic write up and documentation of a Holly Sniper conversion. Kinda remember that the Sniper's injectors were sized for a 6 or 8 cyl. engine and the engine got too much fuel. Have to dig to find the topic in FAQ.

 

Allan Smith with Webcon wrote me that the injectors that come with the Retroject provide 480cc/min @.

 

Hope this helps.

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5 hours ago, xr4tic said:

Lots of people will tell you to just do a 318 EFI, but you need to source all the parts (manifold, coolant outlet, coolant line), fab/buy an idle adapter, fab a throttle linkage solution, fab/buy a TPS adapter, and/or upgrade the TB (stock is pretty small),

The 318i L-jet conversion is pretty basic and having to source all the bits can be time consuming unless you are fortunate enough to locate a complete donor car like this one...

The motivated sellers landlord was giving him flak about it so he was happy for it to disappear.

Replaced a few exhaust manifold nuts, added a few yards of duct tape to the big intake boot and I could have driven it home.

$550 + 30 mile tow home.

Its actually a really straight solid E30 with scruffy interior and paint. Almost seems a shame to break it up.

IMG_2541.JPG

Edited by tech71
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76 2002 Survivor

71 2002 Franzi

85 318i  Doris

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1 hour ago, Mark Sucher said:

I know that there was a member who did an epic write up and documentation of a Holly Sniper conversion. Kinda remember that the Sniper's injectors were sized for a 6 or 8 cyl. engine and the engine got too much fuel. Have to dig to find the topic in FAQ.

 

Allan Smith with Webcon wrote me that the injectors that come with the Retroject provide 480cc/min @.

 

Hope this helps.

It's Holley not Holly, lol. The member you're referring to is @Dudeland, just search Holley Sniper and it should come up. I think he finally got it running good but it took lots of fiddling and wasn't really worth the trouble in the end.

 

I'm assuming that's 2 injectors at 480cc/min, so that would be 960cc/min total and 240cc/min per cylinder. The factory e30 m10 318i injectors are 155cc/min and considered pretty maxed out by aftermarket standards. So you'll get plenty of fuel to make good power, but you don't have as much control of where the fuel goes because your using 2 injectors at the throttle body instead of 1 at each above the intake valve. That's why I suggested a mix of factory BMW and aftermarket for better performance.

 

57 minutes ago, tech71 said:

The 318i L-jet conversion is pretty basic and having to source all the bits can be time consuming unless you are fortunate enough to locate a complete donor car like this one...

The motivated sellers landlord was giving him flak about it so he was happy for it to disappear.

Replaced a few exhaust manifold nuts and added a few yards of duct tape to the big intake boot and I could have driven it home.

$550 + 30 mile tow home.

Its actually a really straight solid E30 with scruffy interior and paint. Almost seems a shame to break it up.

IMG_2541.JPG

Nice find. If it was me I would take out the engine and wiring harness and anything else you want or need. Then put the shell up for sale on craigslist as a good candidate for a engine swap.

 

Someone could buy the nice shell put whatever newer engine they want in, like a m5x or s5x or even n5x or b5x or bigger, they will want to replace/upgrade all the suspension and brakes anyways so it doesn't matter it has the smaller brakes. You could probably get your $550 or more back just for the rolling shell.

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22 minutes ago, 2002iii said:

Nice find. If it was me I would take out the engine and wiring harness and anything else you want or need. Then put the shell up for sale on craigslist as a good candidate for a engine swap.

Thats the plan after taking anything EFI or ignition  related, trans, DS, diff (limited slip) and output shafts. Also keeping the OK blue fabric seats for Franzi,  A 71 in Chamonix with totally sacked OE seats.

"Whats that you say Techie? We thought your car was a 76 named Survivor?"

Yes thats correct.

" Franzi" is a old, dear friend in need of a new home. Looks like my 02 family will be getting an addition soon. More on that as it develops.

Edited by tech71
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76 2002 Survivor

71 2002 Franzi

85 318i  Doris

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2002iii, pretty much any aftermarket ecu will be able to control 4 injectors as well as the 2 in the TBI. I need to educate myself on the in's and outs of the 318i system. Feel like I'm moving from a standing start. So, thanks for the help along the way.

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35 minutes ago, Mark Sucher said:

2002iii, pretty much any aftermarket ecu will be able to control 4 injectors as well as the 2 in the TBI. I need to educate myself on the in's and outs of the 318i system.

Suggest you find out from Webcon the control sequence for the injectors.  Fuel going on a common plenum intake is different than on a port injection for the 318i that controls injectors in semi sequntial pairs in half cycle conrol.  You could get lucky and it works out ok or have a bunch of stuff that won't marry.

A radiator shop is a good place to take a leak.

 

I have no idea what I'm doing but I know I'm really good at it.

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6 hours ago, Mark Sucher said:

2002iii, pretty much any aftermarket ecu will be able to control 4 injectors as well as the 2 in the TBI. I need to educate myself on the in's and outs of the 318i system. Feel like I'm moving from a standing start. So, thanks for the help along the way.

Yes that is true, but I was talking about the advantages of 1 injector per cylinder having better control over where the fuel goes after it exits the injectors into each cylinder right above the intake valve. As opposed to a TBI that has 2 injectors to feed 4 cylinders and acts more like a carburetor dumping the fuel into an intake plenum and letting vacuum pull the fuel into each cylinder with less control over where and how much goes to each cylinder.

 

The evolution of fuel delivery goes something like this: carburetors>mechanical fuel injection>mechanical port fuel injection>electro/mechanical port fuel injection>electronic throttle body injection>electronic port fuel injection>electronic sequential port fuel injection>electronic sequential direct injection.

 

For BMW 4 cylinder examples: 2002 and earlier carburetor>2002tii mechanical port fuel injection>e21 320i k-jetronic electro/mechanical port fuel injection> e30 m10 318i jetronic electronic port fuel injection> e30 S14 M3 and e30 m4x 318i motronic electronic semi-sequential port fuel injection>n43 electronic sequential direct injection.

 

As far as I know BMW has never made a TBI system.

Edited by 2002iii
Added semi-sequintial as per Jimk below
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HI. Completely onboard with the evolution of fuel delivery systems. And have received great, true, factual advice about the advantages of 1 injector per cylinder over TBI. From what I've learned so far, both will require programming ECU's and adding wire harnesses, some add ons, like integrated ignition controls would be the same.  That said, with the goal of improved tractability of my current engine, I'm still curious whether there is a sufficient additional benefit to chasing down the better, 1 injector per cylinder system.

 

Really appreciate your knowledge and seeing things I don't.  Thanks

 

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2 hours ago, 2002iii said:

e30 S14 M3 and e30 m4x 318i motronic electronic sequential port fuel injection

Nope, semi-sequential.  It has 2 injector drivers, 2 injectors paired to each driver.

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A radiator shop is a good place to take a leak.

 

I have no idea what I'm doing but I know I'm really good at it.

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1 hour ago, Mark Sucher said:

That said, with the goal of improved tractability of my current engine, I'm still curious whether there is a sufficient additional benefit to chasing down the better, 1 injector per cylinder system.

@Dudelandplease input your experience with a 2 injector TBI system

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A radiator shop is a good place to take a leak.

 

I have no idea what I'm doing but I know I'm really good at it.

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... and the M20 just got 2 batches as well.  Plus, with the Botch Moronic 1.3, the injectors are spraying

for up to 85% duty cycle, so it's not like the fuel was spraying into an open valve or anything...

 

The Chebby TBI used a smaller and larger injector, didn't it?  The smaller one for idle and cruise,

the larger as a firehose...

 

t

squirt and pray

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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1 hour ago, TobyB said:

... and the M20 just got 2 batches as well.  Plus, with the Botch Moronic 1.3, the injectors are spraying

for up to 85% duty cycle, so it's not like the fuel was spraying into an open valve or anything...

 

The Chebby TBI used a smaller and larger injector, didn't it?  The smaller one for idle and cruise,

the larger as a firehose...

 

t

squirt and pray

I was talking about 4 cylinders so the m20 6 cylinder was not included. Having the fuel spray on top of a closed intake valve is still better than being dropped into an intake plenum.

 

No the chevy TBI's use 2 injectors of the same size that are both used at all times. I think you're thinking of a progressive carburetor that has an idle circuit and cruise circuit and WOT where you might as well be pouring fuel out of a gas can into the intake.

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My post suggesting that Webcon be consulted about injector control concerns the issue that there are 2 throats and I assume each throat has it's own injector.  So between fuel pulses, air with no fuel will be passing the butterfly (and is not the same as port injection where the valve is closed and no flow occurs in the runner between fuel pulses).  Injector duty at engine idle will be small, leaving air flow with no fuel the remainder of cycle time.

 

A GM TBI system had 2 injectors spraying into one throat one injector open at at time alternating.  It also hit the upper side of the butterfly and was dispersed as air pulled the fuel into the intake.

 

Grabbing devices and hoping for the best can lead to disaster.

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A radiator shop is a good place to take a leak.

 

I have no idea what I'm doing but I know I'm really good at it.

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The two injector Sniper EFI system is good.  I would say that there was a significant learning curve for me, as well as some challenges with the application.  

 

The problem with the sniper efi, specifically, is the style of injectors.  The injector is a ring  of holes around the bottom of the barrel, just above the throttle plate. 

 

What I have concluded is this design of injection may require more CFM than the 02 pulls at idle.  As a result you get pooling of fuel under the carb,as the fuel comes out of suspension when passing through the narrow opening between the butterfly and the barrel.  

 

I had significant challenges in configuring it when coming off throttle.  It would constantly overshoot and drop to 3-400 rpm then catch itself.    How I overcame this was to dump fuel and timing at it once under 2K, stopping at 900 rpm,  with the condition that the TPS sensor below 1% (throttle closed).That seem to have worked. 

 

Before I parked it last year I took a good amount of fuel out of the bottom end (1500-4K with TPS above 1%) and the overshoot problem didn't return.  The goal is to eliminate any pooling under the intake.  

 

I had it running quite fat 12.9-13.5 afr as a target, so the new table will lean it out to about 13.2-13.7 afr on average. Having a crank trigger I feel will help with any pre-ignition, and a solid cooling system keeps the temperatures in check. 

 

On cold startup there is a prime funcion, the car starts up great, but I am thinking of backing that off, as that may contribute to some of the fuel pooling.    To be clear, what I mean by pooling is that under the throttle plate the bottom of the carb is very wet,  but not a forming a puddle.    I did keep the coolant jacket as heating the intake helps dry up any fuel that pools. 

 

I did look at the webber retroject, but I didn't have any experience with configuring or programming an EFI system.  Holley had better support and the parts were readily available. 

 

Now that I have one build under my belt, I would take a run at it.   If I had more time on my hands I would develop a kit with a crank trigger, and a MS3 based ECU (perhaps arduino based).   It is a good idea, but the devil is in the details about how it is wired and configured. 

 

The link below will take you to what I feel is one if the better tutorials on wiring.  I respectfully suggest that you go through each one.  After picking up my first soldering iron when I was 7, I still learned things from this tutorial.  Cars and computers are similar in many ways, but require using special techniques to make everything work in a high temperature and dirty environment.   The key takeaway is having a central ground for all your sensors.  If you don't do that, the minor resistance in the chassis of your car will be part of the measurement that the computer sees, and as a result gremlins will procreate. 

 

When you go to plumb the fuel system.  Spend some money and go returnless if you can.  Also put a canister type fuel filter inline. It will save your pump and injectors from getting ruined. 

 

https://www.youtube.com/results?search_query=dave's+wiring+vlog

 

 

 

 

 

 

 

 

Edited by Dudeland
Holley not Holly
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"Goosed" 1975 BMW 2002

 

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I always thought the TBI systems were batch fire, all injectors firing at once, since you have a common plenum.  If you had a dual plane manifold, then having them fire at different times would make more sense.

John Baas

1976 BMW 2002

2001 BMW M5

My Blog!

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