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SU EFI Manifold Update


z-ya

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Someone correct me if I'm wrong but, the design of an intake has a bigger effect on a N/A motor than a boosted one. Therefore any gains from this setup could more easily be seen on the N/A engine. After that, yeah, twin turbo!

 

The twin TBs are really just for a different look on a twin turbo setup. This is what I am leaning towards. I'm going to start mocking things up. The biggest challenge will be the exhaust manifold.

 

how much did it cost you to weld them

 

There is a lot of other work besides just welding in there. It took a lot of time to machine both the EFI flange and the SU manifolds so that they joined squarely. The welding part took the least amount of time. The prep work took about 6-8 hours. The smoothing after the welding is also very time consuming. Cost? Find out what you local welding shop charges by the hour. I have a bartering relationship with a metal fabricator, so he does all my critical welding.

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There is a lot of other work besides just welding in there. It took a lot of time to machine both the EFI flange and the SU manifolds so that they joined squarely. The welding part took the least amount of time. The prep work took about 6-8 hours. The smoothing after the welding is also very time consuming. Cost? Find out what you local welding shop charges by the hour. I have a bartering relationship with a metal fabricator, so he does all my critical welding.

 

That was just what I wanted to hear!

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  • 4 months later...

Yes, I am using the balance tube. Once so that the TB don't need to be precisely calibrated, and it also provides a place to mount the throttle shaft stantions.

 

HPIM0773.jpg

 

I have completed port matching the manifold to the head. I have also smoothed the inside of the manifold where the EFI manifold was grafted to the SU manifold. There were some bumps that needed to be smoothed out where the two manifolds were welded together.

 

The plan as of today is to use this manifold setup on a 3.1L NA sleeper. I will be retrofitting a stock 240Z air filter to attach to the TBs. It should make people do a double take. The car it is going into is a 71 which will be setup as a nice street modified Z. It will look mildly modified, but it have all the goodies underneath.

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Can't wait to see more! :D

What kind of benefits would one see on this style set up vs a stock mani on a boosted motor?

I'm building an l28et in the future and I still have the carb set ups off of 2 240's laying around ;)

How would one calibrate a set up like this with ms?

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the runner diameter of the stock intake manifold is 38 mm. The intake valve diameter is something like 42-45 mm... or larger. You do the math, but keep in mind that doubling the diameter of a channel increases its cross-sectional area by (1/2 x Diameter)^2 x pi. I haven't personally mic'd the interior diameter of the SU manifold, but I know PLENTY of people that make plenty of power out of a pair of roundtops.

 

Z-ya: my family and I were talking about your setup today. Poor Mom :-

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Can't wait to see more! :D

What kind of benefits would one see on this style set up vs a stock mani on a boosted motor?

I'm building an l28et in the future and I still have the carb set ups off of 2 240's laying around ;)

How would one calibrate a set up like this with ms?

 

There will be a balance tube, and only one TB will have a TPS. So except for getting the two TBs butterflys set close, it should work like a single TB intake manifold.

 

Pete

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Really, as long as you have a linkage with little or no play, the TPS can go just about anywhere in the system. Inside the car on the throttle pedal pivot point is nice and clean, and cool, and doesn't mean you have to open the hood to connect to it for troubleshooting. Only if your linkage breaks will it go kaflooey...and in that case you won't be moving anyway.

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Tony,

 

The linkage is all stock Nissan, so there is very little play from TB to TB. Worst case would be 2 times the max play from a one TB stock Nissan setup. Slapping a TPS onto the side of one of the TB is a lot easier than rigging it up on the pedal (I just love getting under the dash in an S30). A 240SX TPS will bolt to the 280ZXT TB without any modifications.

 

I actually was looking closely at using a set of SUs to use just as TBs, but there is no place to easily mount a TPS. I'm wondering if on MSII you can use manifold vacuum change for throttle enrichment (I know other ECUs can do this). Or, I could mount the TPS under the dash. Mmmmm, thinkin' stealth mode again.... I'm liking this idea!

 

Pete

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I'm wondering if on MSII you can use manifold vacuum change for throttle enrichment (I know other ECUs can do this).

 

I know for a fact on MS-I with the MSnS-E code, you can. A few friends of mine had problems with the acceleration enrichment causing the engine to stumble for a sec because it saw a tps change that wasn't there. They switched to 100% map based accel (isn't Cygnusx1 running that, too?), so besides datalogging, their TPS sensors don't do a thing.

 

So the SU/TB idea is a go :2thumbs:

 

Edit: Yes, Cygnusx1 is (or at least was) running full map-based accel enrich on his MSII.

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I thought I had seen it in the "Extra" code, but wasn't sure. Nice to know it is in the MSII code as well since that is what I will be running on this setup. Running a shielded cable fro the TPS sensor can sometimes fix these TPS glitch problems. If you run straight wire for everything you can run into these kinds of problems.

 

Yes, I think I am going to start screwing with the SUs as throttle bodies now.

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If you go with SUs as throttle bodies, what will you be doing with the TBs you had prepped for this manifold? I have plenty of NA 280ZX TBs I can work with, and the junkyard is full of nissan throttle bodies... but since you already had these dressed for use in this position.... Personally, the appeal *I* find in this design is the ingenuity and differentiation. The concept of going "sleeper," with gutted carbs amuses me, but it doesn't feel like what *I* want, yanno?

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  • 7 months later...

Not to jack my own thread, but a friend of mine has a Cosworth Vega with 41k miles on it. Motor was sleeved and had some mild head work done. Made almost 130WHP on a Dynpack:

 

Picture%202_3.jpg?disposition=download

 

Dotted plot is before we took the cover off the air box....

 

 

Pete

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To contribute to Z-Ya's self-jacking...er...

 

It makes you think when those crybabies in car 929 protested our little L20A powered 280Z 2+2, huh?

 

That Cosworth engine and EFI combination is worth 345HP at 12,000 rpms if they have the ability to tune it properly. They went out and bumped the record (I guess because we lit the fire under their butt...)

 

But that protest...bad form!

 

I think the Cosworth Vega is the only engine I've seen with an Emission Control Device that is so pretty, the engine looks WORSE (if not less intimidating) with it off, than with it on...

 

That being the A.I.R. Injection Tubes across the top of the head. Nice big chrome things that scream 'KILLER TECHNOLOGY! DON'T MESS WITH ME! LOOK AT MY CHROME!!!'

 

LOL

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