KMead’s Microsquirt Build. Formerly: Looking to use PBS DCNF intake manifold for FI

[kmead]

This started out as a want ad in the for sale section, as often happens it trailed off into a very interesting discussion around approaches to how one might fiddle the air intake and injectors for use with Micro/MegaSquirt.

So in that spirit the thread has been moved to the Discussion Forum where we can continue to make this a great learning discourse.

Looking for a PBS type manifold which mounts DCNF carbs. I prefer this unit as the runners are more inline with the openings in the head.

It doesn’t have to be perfect. I would also be happy to look at alternative manifolds as well.

I don’t expect to install DCNFs (sorry Carl) as this is intended to support an alternative approach to fuel injection. Using either individual throttle bodies, DCNF throttle bodies or a melange of making a short intermediate manifold to carry the injectors and modifying the existing FI intake barrel to accept the intermediate manifold below. Another choice would be something like TonyK’s Megasquirt manifold which placed the injectors above the runners with nice trumpets, shooting down into the manifold (as I recall).

I know these are available on Evilbay but being the cheap assed bastard I am, looking to not get abused by Ebay and don’t think I know the seller.

Thank you.

Pics of the Ebay unit, you can see the PBS label in the casting.

 

[carl]

Lots...most....bikes now come with ITB injection. I'm waiting for someone to do that conversion. Remember when everyone wanted to put motorcycle carbs on their cars.

 

[Dr.Jeff]

Hopefully I'm not derailing your thread already. But I know from experience you and I tend to have similar views about such topics so I'd like to offer my thoughts on this.

If you go with a DCNF style manifold then I think I'd stick with the DCNF style throttle bodies...for several reasons. However they are rather expensive in my cheap ass opinion.

If you go with the factory X style FI intake runners then I'd mount them directly to the head and adapt individual TBs onto them. (Not sure if that was what you were thinking already or not). That way you can utilize the existing injector mounts and install the larger Bosch injectors that are a direct fit (we've discussed these injectors before but I can find the link if needed).

There are aftermarket "universal" ITBs available but they are also quite expensive. I think I'd be on the lookout for something that can be pirated from a production vehicle and adapted to fit. That's probibly your thought in the post about Bobcat's setup?

Another option I might consider is making your own manifold from scratch. Generic Fiat SOHC style flanges are available in steel to build from, but it's still a considerable amount of fabrication from there. However the same with a couple of the other options you've mentioned. I have a set of excellent bike carbs that I'd like to make a custom manifold for, just for the fun of it (Carl, some of us still want to do it ). Then I can add the bike nitrous oxide system I also have.
@carl, I've thought about the use of bike ITBs before. I believe (but not sure) the ITBs from bikes are smaller than desired for our engines? Although they shouldn't be much different size from bike carbs so they might work.

I suppose one last consideration might be to start with the full factory FI manifold and replace it's restrictive throttle body with a larger one (another member did this for his turbo build*). Although that is not independent TBs, it will flow almost as well.

* I thought I had a pic of his manifold saved but now I can't find it. However this is what he did. Removed the stock TB from the middle and welded on a mount for a aftermarket large TB on one end:

If this were my project I'd be inclined to build it off the factory FI runners. Their curve allows the TBs to be located upward, allowing plenty of rear bulkhead clearance, while keeping the runner length fairly long. They can be ported more than enough if the runner bore size is a concern (although that is not the restrictive area with these heads). The upper flanges could be retained and make an adaptor to go from it to whatever TBs you select (again, that may be what you already said). Or the upper flanges could be cut off the runners and fabricate new mounts for the TBs.

 

[JimD]

Chris Obert's site says he can get one built for you.

 

[kmead]

Hopefully I'm not derailing your thread already. But I know from experience you and I tend to have similar views about such topics so I'd like to offer my thoughts on this.

If you go with a DCNF style manifold then I think I'd stick with the DCNF style throttle bodies...for several reasons. However they are rather expensive in my cheap ass opinion.

If you go with the factory X style FI intake runners then I'd mount them directly to the head and adapt individual TBs onto them. (Not sure if that was what you were thinking already or not). That way you can utilize the existing injector mounts and install the larger Bosch injectors that are a direct fit (we've discussed these injectors before but I can find the link if needed).

There are aftermarket "universal" ITBs available but they are also quite expensive. I think I'd be on the lookout for something that can be pirated from a production vehicle and adapted to fit. That's probibly your thought in the post about Bobcat's setup?

Another option I might consider is making your own manifold from scratch. Generic Fiat SOHC style flanges are available in steel to build from, but it's still a considerable amount of fabrication from there. However the same with a couple of the other options you've mentioned. I have a set of excellent bike carbs that I'd like to make a custom manifold for, just for the fun of it (Carl, some of us still want to do it ). Then I can add the bike nitrous oxide system I also have.
@carl, I've thought about the use of bike ITBs before. I believe (but not sure) the ITBs from bikes are smaller than desired for our engines? Although they shouldn't be much different size from bike carbs so they might work.

I suppose one last consideration might be to start with the full factory FI manifold and replace it's restrictive throttle body with a larger one (another member did this for his turbo build*). Although that is not independent TBs, it will flow almost as well.

* I thought I had a pic of his manifold saved but now I can't find it. However this is what he did. Removed the stock TB from the middle and welded on a mount for a aftermarket large TB on one end:
View attachment 70238

If this were my project I'd be inclined to build it off the factory FI runners. Their curve allows the TBs to be located upward, allowing plenty of rear bulkhead clearance, while keeping the runner length fairly long. They can be ported more than enough if the runner bore size is a concern (although that is not the restrictive area with these heads). The upper flanges could be retained and make an adaptor to go from it to whatever TBs you select (again, that may be what you already said). Or the upper flanges could be cut off the runners and fabricate new mounts for the TBs.

Yeah I am of two minds, spend the money and just deal with the reality of Micosquirt and its harness to get something up and running.

I remember the pain Hussien went through with reworking the OE intake and have always disliked the short hoses and angled injectors.

The other is to make up a manifold from existing parts. The idea is use the DCNF manifold with an intermediary manifold section to then mate to a modified OE Fiat log. The intermediate manifold would likely be steel and fabricated in my works model shop (we have a program for ‘government work’ where we pay to the United Way for the labor and materials). This intermediate manifold would bolt down to the DCNF manifold and carry the fuel injectors. Due to the angle of the DCNF manifold the injectors in this could basically be pointed right at the intake valves. I would then modify the standard injection system log to cut out the existing runner sections and weld in a new mounting with downward facing studs to attach it to the intermediate manifold.

I need to layout the relationship of parts better to try to understand if there is room at the back of the DCNF manifold for the injectors to stick out.

The image below is a rough indication of the intermediate manifold with approximately the injector location.

This image represents the log attached to the intermediate manifold

I am still roughing this out in my mind. I am not necessarily committed to ITBs or a single butterfly like what is on the OE log which is where many modern production cars have gone so it can’t be all bad.

Sorry the illustrations are so rough I just whipped them up.

 

[kmead]

Lots...most....bikes now come with ITB injection. I'm waiting for someone to do that conversion. Remember when everyone wanted to put motorcycle carbs on their cars.

I have been looking at that as well Carl. The Suzuki 750 ITBs seem like good candidates but the issue I keep seeing is getting the ITBs close enough together to work with the DCNF manifold.

Of course going to a completely new manifold to mount them with some splay to accomodate the spacing would do the trick. At which point why not go for the IDF manifold and IDF throttle bodies which are pretty inexpensive from China.

 

[JKIDD]

Sorry the illustrations are so rough I just whipped them up.

 

[fiatfactory]

Thats going to a lot of trouble to reposition the injectors and get rid of the manifold with the flow restrictions at that point.

PBS maniufold is a split the difference, so the base flange will be 4 degrees off horizontal, which helps with your injector "aiming" , but a 128 manifold will position the flange a full 8 degrees off horizontal which will improve the angle even more...

A lot of aftermarket systems that retain a single plenum above the runners/ injectors also often go to twin (staged) butterflies, keeps the air speed high at low throttle and provides sufficient breathing when the secondary is opened.

maybe a yugo efi manifold might be a better place to start, the runners are straight, injectors are central...

or if you go bike carbs, hunt down and buy the manifold that mounts them.


Alfa Suds with EFI used an IDF compatible throttle body.

you can find these pretty cheap.

SteveC

 

[Dr.Jeff]

Yeah I am of two minds, spend the money and just deal with the reality of Micosquirt and its harness to get something up and running.

I remember the pain Hussien went through with reworking the OE intake and have always disliked the short hoses and angled injectors.

The other is to make up a manifold from existing parts. The idea is use the DCNF manifold with an intermediary manifold section to then mate to a modified OE Fiat log. The intermediate manifold would likely be steel and fabricated in my works model shop (we have a program for ‘government work’ where we pay to the United Way for the labor and materials). This intermediate manifold would bolt down to the DCNF manifold and carry the fuel injectors. Due to the angle of the DCNF manifold the injectors in this could basically be pointed right at the intake valves. I would then modify the standard injection system log to cut out the existing runner sections and weld in a new mounting with downward facing studs to attach it to the intermediate manifold.

I need to layout the relationship of parts better to try to understand if there is room at the back of the DCNF manifold for the injectors to stick out.

The image below is a rough indication of the intermediate manifold with approximately the injector location.

View attachment 70242

This image represents the log attached to the intermediate manifold
View attachment 70241

I am still roughing this out in my mind. I am not necessarily committed to ITBs or a single butterfly like what is on the OE log which is where many modern production cars have gone so it can’t be all bad.

Sorry the illustrations are so rough I just whipped them up.

Nicely done with the images.

OK, now I better understand what your plan is. Since I don't see ITBs in there, I assume this will utilize the Fiat plenum throttle body?

Frankly all that really doesn't make a ton of sense to me. For one thing I believe you want the injectors as close to the head as possible. Plus you still have the stock, highly restrictive butterfly. You could modify the TB, and remove other unnecessary stuff from the stock plenum. But if you are going to make a intermediate manifold then why use the Fiat plenum? Just make a better one incorporated with the intermediate adaptor. Or better yet, why use the DCNF manifold, just make the whole thing custom to your design. As much as I love your idea, and with all due respect, to be honest I think a DCNF manifold, adapted to the Fiat plenum, with a modified TB and custom injector mounts is a compromised design and will end up less effective than other options.

Similarly, utilizing ITBs from a bike or other vehicle, or the DCNF injector bodies, on the DCNF manifold also seems like a compromised design. Since the ITBs/DCNF TBs already incorporate injectors it precludes your idea of mounting the injectors in a better location. So why use a DCNF manifold, with its 90 degree flow bend?

Really, using the complete stock FI manifold assembly with a larger butterfly seems better than crafting all this up. If the stock location of the injectors bothers you then you can add new injector mounts wherever you like on the stock manifold. But using the larger, direct fit injectors on the stock manifold is a better approach in my opinion; the location of the injectors isn't that bad and you won't gain enough from relocating them to warrant the mods. It's kind of a go big or stay stockish situation.

Of course all this depends on your intended use of the engine. Is it for a race/track car? Or a street car? If a race engine then you want short runners (like the PBS manifold), but if a street engine then you want longer runners (like the stock ones).

I see "Sherry Berg" also offers affordable DCOE style injector bodies. To go with a DCOE style manifold. That overall setup will far out flow any of the other options discussed. It will require modifying the rear bulkhead a little but that is much easier than making custom manifolds or adapting other things together....as the manifold and TBs would be a direct bolt-on.

https://www.aliexpress.us/item/3256802478356243.html?pdp_npi=2%40dis%21USD%21US%20%24185.00%21%24138.75%21%21%21%21%21%402101f6b616756261530151097e27ce%2112000021616969454%21btf&_t=pvid%3Ae47e8179-fbde-44d1-9ea8-3efeff29fd71&afTraceInfo=1005002664670995__pc__pcBridgePPC__xxxxxx__1675626153&spm=a2g0o.ppclist.product.mainProduct&gatewayAdapt=glo2usa&_randl_shipto=US

 

[carl]

Since I'm the first one who vectored off this "want ad" I'll now notice this is in the for sale/wanted department and not tech which is where it slid into. Anyone interested in ITBs for an X may not get all this as it's listed as a want ad.

Kmead, I apologize.

 

[Dr.Jeff]

Since I'm the first one who vectored off this "want ad" I'll now notice this is in the for sale/wanted department and not tech which is where it slid into. Anyone interested in ITBs for an X may not get all this as it's listed as a want ad.

Kmead, I apologize.

I also took it away from a "for sale" listing and toward a "tech" one. I'm sure Karl is willing to start another thread and copy this to it. Until he does, I'll add a little more info.

This got me thinking about the possible options for a improved FI system on the X. To me the idea of using Weber DCOE style TBs and manifold really seems the best route. Especially with the affordable DCOE TBs from China. I know the Weber clones the same company makes have had minor issues with things like the tiny passages for jets or air bleeds; on occasion they have been found to need a little cleaning up. But since these TBs are so basic and don't have tiny passages like that, I think they should be fine.

Combine them with a DCOE manifold for the SOHC:

FIAT X19 FIAT 128 WEBER DCOE MANIFOLD & LINKAGE FIAT HI PERFORMANCE MANIFOLD | eBay

FIAT X19 ~ FIAT 128. NEW INTAKE MANIFOLD WITH LINKAGE AND MOUNTING HARDWARE ~.

www.ebay.com

FIAT 128 RALLY COUPE BERLINA ZASTAVA YUGO X1/9 BERTONE INLET...

This is new inlet manifold for Weber DCOE, Dellorto DHLA, Solex 40 ADDHEcarburettors for FIAT SOHC engines 1,1-1,6 from: Fiat 128 Berlina, Special, Rally, Sport Coupe, Familiare 1,1-1,3 Fiat X1/9 Bertone 1,3-1,5 (we can produce with angle for X1/9) Fiat Ritmo/Strada/Regata 65, 75 1,3-1,5 Fiat...

stolesraceshop.com

You also have readily available throttle connections for those DCOE linkages, air filters, heat shields, and all the other bits needed to complete the package....and all at affordable prices.
Imagine something like this, but with FI TBs instead of carbs (also with only a hole through the rear panel):

Although the DCOEs have a bit wide footprint for the X's ports, it is a straight, single plane, direct shot. And flow wise that will far outweigh the bends and curves of any other alternatives we've discussed. The only option that I can think of that would be better is fully independent TBs on custom manifolds that are a straighter aim than the DCOE's. And even then you would not be able to get them 100% straight, as the TBs will require more room between them than the head's ports allow.

Especially when you consider the ease and cost of the DCOE TB setup, I don't see how it can be beat (unless cost is no object and you have everything custom fabricated). Maybe something like this:

 

[dllubin]

I also took it away from a "for sale" listing and toward a "tech" one. I'm sure Karl is willing to start another thread and copy this to it. Until he does, I'll add a little more info.

This got me thinking about the possible options for a improved FI system on the X. To me the idea of using Weber DCOE style TBs and manifold really seems the best route. Especially with the affordable DCOE TBs from China. I know the Weber clones the same company makes have had minor issues with things like the tiny passages for jets or air bleeds; on occasion they have been found to need a little cleaning up. But since these TBs are so basic and don't have tiny passages like that, I think they should be fine.

Combine them with a DCOE manifold for the SOHC:

FIAT X19 FIAT 128 WEBER DCOE MANIFOLD & LINKAGE FIAT HI PERFORMANCE MANIFOLD | eBay

FIAT X19 ~ FIAT 128. NEW INTAKE MANIFOLD WITH LINKAGE AND MOUNTING HARDWARE ~.

www.ebay.com

FIAT 128 RALLY COUPE BERLINA ZASTAVA YUGO X1/9 BERTONE INLET...

This is new inlet manifold for Weber DCOE, Dellorto DHLA, Solex 40 ADDHEcarburettors for FIAT SOHC engines 1,1-1,6 from: Fiat 128 Berlina, Special, Rally, Sport Coupe, Familiare 1,1-1,3 Fiat X1/9 Bertone 1,3-1,5 (we can produce with angle for X1/9) Fiat Ritmo/Strada/Regata 65, 75 1,3-1,5 Fiat...

stolesraceshop.com

You also have readily available throttle connections for those DCOE linkages, air filters, heat shields, and all the other bits needed to complete the package....and all at affordable prices.
Imagine something like this, but with FI TBs instead of carbs (also with only a hole through the rear panel):


Although the DCOEs have a bit wide footprint for the X's ports, it is a straight, single plane, direct shot. And flow wise that will far outweigh the bends and curves of any other alternatives we've discussed. The only option that I can think of that would be better is fully independent TBs on custom manifolds that are a straighter aim than the DCOE's. And even then you would not be able to get them 100% straight, as the TBs will require more room between them than the head's ports allow.

Especially when you consider the ease and cost of the DCOE TB setup, I don't see how it can be beat (unless cost is no object and you have everything custom fabricated). Maybe something like this:
View attachment 70272

One major advantage of ITBs is throttle response because you can get the throttle body closer to the intake. That last photo looks like the throttle bodies are quite far away which kind of defeats the purpose.

 

[Dr.Jeff]

One major advantage of ITBs is throttle response because you can get the throttle body closer to the intake. That last photo looks like the throttle bodies are quite far away which kind of defeats the purpose.

Agreed. And that's where one difference between a street only engine with a FI plenum (smoother running) differs from a race-only individual injection (quicker response) comes into play.
That was the first pic I found with anything of the sort. Somewhere there's another example with a slide valve throttle.

 

[kmead]

Since I'm the first one who vectored off this "want ad" I'll now notice this is in the for sale/wanted department and not tech which is where it slid into. Anyone interested in ITBs for an X may not get all this as it's listed as a want ad.

Kmead, I apologize.

It’s all good. I expected it to go this way. Perhaps I will have Jim slide it over to the Workshop or Discussion forum and adjust the starting post

 

[fiatfactory]

Isn't it amazing how some people want you to spend all your money to flesh out their idea....

Honestly Karl, your original idea was super simple by comparison to some options presented requiring a load of custom fabrication...

The dcnf port spacing is what you want, you're on the right track. If you were to custom fabricate a manifold then you'd have it angling up, following the port's natural angle up from horizontal.

dcoe manifolding is not a more efficient flow path if it flattens off to keep the carbs level... BTDT have a flow bench and have measured the flow losses... on top of the port width issue creating more bends

if you ran throttle bodies one of the biggest advantages they offer is not needing to keep them level, and by keeping them level to fit the bodywork / mate with existing manifolds would be throwing that advantage away.

SteveC

 

[Dishy]

Kmead, I am part way through working out a similar idea, but based on my IDF manifold. I plan to use throttle bodies from a 2000's Honda VFR800.

https://www.ebay.com.au/itm/255312380661

The bore spacing is 1mm different to the IDF's on the car at the moment, which should be easily taken up with mikuni style carburetor adapters. I can't remember the part number at the moment.

The throttle linkage from the webers should transfer across to the new throttle bodies because the bore spacing is the same.

The big thing I am stuck on at the moment is I need a lathe to shorten the central shaft the throttle plates mount on so that I can fit the weber return spring instead of the big motorcycle return springs.

I plan to keep the injectors, fuel reg and throttle position sensor from the bike.

Dishy


Edit: I think these are the adapters.

Parts Unlimited - 07-100-15 - Carburetor Mounting Flange for sale online | eBay

Find many great new & used options and get the best deals for Parts Unlimited - 07-100-15 - Carburetor Mounting Flange at the best online prices at eBay! Free shipping for many products!

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[PaulD]

One major advantage of ITBs is throttle response because you can get the throttle body closer to the intake. That last photo looks like the throttle bodies are quite far away which kind of defeats the purpose.

I built the engine pictured with the long intake manifold. The build was a1600 stroker engine with goal of maximum torque, hence the long intakes. Here is a dino sheet, crank HP:

There is no hesitation in the throttle response, indeed with a light flywheel and kevlar clutch it is difficult to make a gentile start. I suspect the long intakes cost me some horse power, although the straight shot to the valves helps

 

[MikeHynes]

Karl,
Here are a couple of pics of a custom manifold that one of our members built for his (very successful) autocross racecar. Note the length of the runners. I believe they were sized to maximize performance with a mostly stock engine.

I believe the longer runners favor lower RPM torque. A shorter runner length will favor high RPM power and sacrifice low RPM HP/torque.
It appears that the injectors are placed fairly close to the stock location, and very close the the inlet runners of the cylinder head. (It also has a slide throttle.)

 

[PaulD]

Karl,
Here are a couple of pics of a custom manifold that one of our members built for his (very successful) autocross racecar. Note the length of the runners. I believe they were sized to maximize performance with a mostly stock engine.

I believe the longer runners favor lower RPM torque. A shorter runner length will favor high RPM power and sacrifice low RPM HP/torque.
It appears that the injectors are placed fairly close to the stock location, and very close the the inlet runners of the cylinder head. (It also has a slide throttle.)
View attachment 70358View attachment 70359

Note the eccentric throttle pulley to even out the throttle response.

 

[Bjorn Nilson]

Jenvey makes throttle bodies, runners etc that may be an option. A X1/9 friend in Sweden put ITB's on his car with good result.

Fuel Injection Throttle Bodies, ITB, EFI, Webshop, online store by Jenvey - Jenvey Dynamics

Motorsport, Classic car, aftermarket and green engine Fuel Injection Throttle Bodies, ITB, EFI, Webshop, online store by Jenvey - Jenvey Dynamics

store.jenvey.co.uk