Making my own EFI intake system

[Derek]

Hi

This is my first post here. I have a 73 240 that I've owned for 26 years. It's been in storage for the last 10 and i recently decided to get i on the road again. I'm a CNC pattern maker for the sand casting industry and have my own shop. I decided that I needed to design and cast something cool for the car and thought I'd do something unique like a triple SU set up. Then after digging around a little I see that Z therapy is coming out with one. So much for being unique! After some more digging I came across the Megasquirt site. This seemed to be a lot slicker than three SUs and and being a bit of a geek I love the open source concept of it.

So here's my design criteria:

#1 Look Cool

#2 Look Really Cool

#3 Actually Run

I'm opting for 6 individual throttle bodies in two banks of three. I'm running a stock L28 block with a E88 head. I plan on keeping the throttle bodies fairly long to improve my bottom end. The throttle shafts will be vertical as opposed to horizontal for ease of machining.

 

 

Right now I have the the head and exhaust modeled in 3d and I'm starting to do some preliminary design on the throttle bodies.

Here's a few questions.

Is there any benefit to tapering the throttle body. I drew it up going from 2†tapering down to 1.5†because it met design criteria #1 and #2

Is there any reason I shouldn't mount the injector as close to the intake port as possible.

Here's a link to a jpeg of where I'm at right now.

 

Thanks in advance

Derek

[naviathan]

You want torque, pull the injectors out more. The further from the valve the more time the fuel has to atomize which creates a better burn in the cylinder. I like the tapering. That should really increase air velocity into the cylinders. It looks like you have the right idea so far, but you may want to check out Top End Performance. They have a tripple throttle body setup that's 3 banks of two throttles instead of 2 banks of three. http://www.racetep.com

[Chewievette]

On a side note, I found this cool vid of a triple SU car running...

 

I am currently in the midst of designing an individual throttle body intake for my car. The basic design is done but I've been laying out the flanges in CAD all week. I am very interested in seeing you progress, I always like seeing unique parts in action. I hope to have some progress of my own to post soon.

[z-ya]

Hear is the twin SU L6 FI manifold work I've been doing with a friend. Still got plenty of smoothing to do. Will be using 280ZXt throttle bodies as they don't have a lot of junk on them, and they are slightly larger than the SU flange (50mm). The bolt pattern of the ZX TB is slightly different, so the original SU mounting holes were welded up. New holes for the ZX TB will be drilled and tapped.

 

 

 

I'll post more photos after it is all smoothed out and the linkage is done.

[Chewievette]

Thats a nifty idea, I thought about it for a second once but moved on for whatever reason. Are you going to use stock EFI injectors & rail or are they going to be something else?

[z-ya]

I'm using a Palnet rail, and 450cc/min DSM injectors (o-ring).

 

I've had these manifolds and TBs kicking around for a while, and decided to do something with them. I think it's going to look pretty cool when done. The performance should be good too.

[Roostmonkey]

did someone say twin turbos??

[Chewievette]

did someone say twin turbos??

Not that I know of... However, it is on my to do list.

 

That twin SU manifold should be really cool when you get it running. I wonder how many people will be able to figure out out. btw, what are you doing for linkages? are you going to link the TBs together with a shaft and hook the input to one or are you going to hook the input to both individually? My daily driver uses twin TBs with a syncro shaft that I always thought looked dead sexy.

[Xander]

Z-ya, I had this idea for a while too. I was going to use two TB's of a v6 pontiac fiero. These are almost an exact fit. The boltholes line up perfectly. They also come with the right TPS. The Idle air comtroller is a 4 pin stepper motor which can be controled with megasquirt II.

[Guest 280ZForce]

damn, i wanna post progress pics of my intake (single tb), but I think I'll bite my tongue until I actually have it back. It's all finished up, just waiting to see the final pics of it coated. My powder coater is supposed to be shipping it out to me today (well Saturday) I hope. It's gonna be a cool surprise for everyone here on hybrid.

 

But besides that, the idea of ITBs and what not is an awesome idea, maybe I'll go that way one day if my route doesnt produce the air flow I need (which I'm sure it'll do just fine).

[z-ya]

For linkage, I'm going to use stock 280Z linkage hardware. I think it's going to work out great, and each TB will be individually adjustable.

 

Most likely these manifolds will go on my stroker project with stock RB26DETT turbos.

[Derek]

Ok

Here's the latest design.

Overall legnth is 10†which is the distance from the face of the SUs to the head. The downward angle is 16 degrees which lines up pretty well with the port entrance. The individual throttle bodies will be angled in the horizontal plane so that they're all the same length. The bore comes out straight for 3†and then tapers out 2.5 degrees for 7 inches.

 

 

Some things I need to finalize.

Injectors. I really don't like the look of fuel rails and they ad a level of complexity on the machining end. I'd love to locate a screw or clamp in style with a threaded top that would accept a banjo style fitting. I could hard line it to a central fuel block with more banjo fittings. I think this would have a very old school mechanical injection look and would satisfy my design criteria #2 “Look Really Cool “

 

 

Air filtration. I suppose I could put flanges on the ends of the throttle bodies and use an air box. I'm not too crazy about the looks of an air box and would love some sort of alternative. I could cast a step on the inside of each throttle body and use some sort of mesh-foam-mesh arrangement that would fit inside them. I really don't know how practical this would be. Cleaning air filters every other day might not be very fun.

 

 

Linkage. At this stage I'm thinking separate levers and rods connected to a central bell crank and cable driven. I'm also working out the individual idle screw and return spring design.

 

 

Here's a cool shot looking down the throat WFO

 

 

Thanks for all the help.

Derek

[Chewievette]

Thats looking Very cool derek, my only concern is if it will hit the hood. The engine tilts a little bit twards the pass side and with the up angle you have on the intake, it looks like it will hit, but I could easily be wrong. I know some of the guys running webers have open trumpets with no filtration and have not had any problems. For the fuel, you could do a "spider block" on top of the valve cover that runs individual lines to each injector. This would be pretty easy with the stock Z injectors since they have hose connections. I'll try to dig up some pics to show what I'm talking about.

 

Here is an aircraft engine with mechanical fuel injection using a flow divider (aka, Spider)

[ww]

Hear is the twin SU L6 FI manifold work I've been doing with a friend. Still got plenty of smoothing to do. Will be using 280ZXt throttle bodies as they don't have a lot of junk on them, and they are slightly larger than the SU flange (50mm). The bolt pattern of the ZX TB is slightly different, so the original SU mounting holes were welded up. New holes for the ZX TB will be drilled and tapped.

 

Pete, that looks like it's gonna come out pretty nice. After all the work you've done mating the two intake manifolds, I'm curious if you think it would have been easier to build up and drill injector bungs onto the E88 manifold, eliminating the need to source the two manifolds and splice them together?

 

I have a spare intake manifold (N33?) from a '72 240Z that I was considering using. Then I thought it would be cool with a set of TWM's new SU ITB's then switched back to using 280ZX TB's to use as an MS&S learning tool!

 

Of course, I have way too many projects in the works...

[z-ya]

Pete, that looks like it's gonna come out pretty nice. After all the work you've done mating the two intake manifolds, I'm curious if you think it would have been easier to build up and drill injector bungs onto the E88 manifold, eliminating the need to source the two manifolds and splice them together?

 

I have a spare intake manifold (N33?) from a '72 240Z that I was considering using. Then I thought it would be cool with a set of TWM's new SU ITB's then switched back to using 280ZX TB's to use as an MS&S learning tool!

 

Of course, I have way too many projects in the works...

 

I had two sets of SU manifolds, and at least 5 EGR EFI manifolds, so sourcing the manifolds was easy. I wanted to use a Palnet rail I have, so I wanted the stock spacing. Getting six new injector bungs to line up for an o-ring rail would be near impossible. So I think it was easier to splice, and smooth, than retrofitting injector bungs onto the E88 manifolds directly.

 

The ZXT TBs are fine for my application, and free. As per my previous post, the linkage is going to work out great also.

[Careless]

Getting six new injector bungs to line up for an o-ring rail would be near impossible.

 

just curious as to why you think so

[Accurate Injection]

Come On Z-ya! I have 2 Throttle Bodies and a Rail waiting on ya! Hahahah! The 6 Injectors would be better than 2 for an SU application, but 2 extra mounted in the Throttle Bodies could prove useful! LOL!

 

Kevin

[z-ya]

Come On Z-ya! I have 2 Throttle Bodies and a Rail waiting on ya! Hahahah! The 6 Injectors would be better than 2 for an SU application, but 2 extra mounted in the Throttle Bodies could prove useful! LOL!

 

Kevin

 

Hey Kevin,

 

No offense against your stuff, but I've got all this crap hanging around my shop, and I decided to try and do something with it. If your TBs will bolt up to SU manifolds, and can add two more injectors, I may look you up if I need more fuel than 6 @ 450cc/min.

 

What I've seen of the SU replacement TBs is that they only give you one inector per TB. This is great for a 6 TB setup, but not so great with two. For 400+ HP applications, those are some mighty big injectors. Plus you still have the fuel distribution issues with the SU manifolds.

 

just curious as to why you think so

 

Get a hold of some SU manifolds, a fuel rail, and you'll see what I mean. You can do it with some HKS styler injector holders, but they will be firing straight down. I wanted them firing into the stock injector ports. Because the SU manifolds use the other bolt holes on the head, it becomes extremely difficult. If you have a saw, end mill, and you are good at TIG welding aluminum, it is a much easier approach.

[Accurate Injection]

Hey Z-ya I agree with you 100% @ a stock Level of 150hp it would take 55lbs/hr or larger to flow enough fuel! Fuel Distribution is a another issue too! Stock motor SU Replacement is what we designed it for! Damn it looks good though don't it? Hahahaha!

 

Those are 45mm with the SSS Manifold Bored and Blended to aid the additional air flow!

 

Kevin

 

[Tony D]

Someone who is infrequent on this forum currently has converted SU's with 1000 cc/min injectors in them running on his 3.0L Racer, we were supposed to do a joint dyno day Friday, but everything fell through. So tuning of the final maps and 'decisions' to be made about injector placement of the two injectors still remains up in the air till that dyno testing is concluded.

 

This setup is the 'ultimate quick and dirty' EFI conversion of SU's. The results should prove very educational.

 

Pete, you have 'peripheral knowledge' of his setup. I've no real photos to speak of thusfar, when I do, I can distribute them.