simpson36

This is the second of three interesting alternative induction projects I am working on:

First mock up:



The throttle bodies are bored-to-the-max Crossfire Throttle bodies complete with functioning balance ports:



I will be making the custom linage and brackets as well as designing and building the fuel system. Here is the mock up of the fuel:



When complete, this wil go on a 406 CI high reving motor with all forged internals in an '84 Vette.

USALT1

Is 2.375 the TB diameter? At first glance, I was thinking that even with 2 little TB's you wouldn't have enough airflow for a 406. I did the math & you will have 8.85 sq/in. A 780 holley has 8.91 sq/in so your airflow should be ok. I'm setting up an old eldebrock crossram with 390hp's for my '65 Coupe, I'm curious to see how your's works with TB's.

vettesbydesign

What intake?Just curious.I have a old X1 at a friend's right now getting done,so I can get it back on the car.Alot of gas for my little DZ.

I have a old crossram w/a pr of Holleys for 500.00,and shipping.The carbs need gone thru,but work fine...

USALT1

The intake I have is an Edlebrock SRT10, same layout as the Z/28 Crossram, but a smoother top.

Black 82

Cool. Are you gonna make adapters or a whole new top plate?

Who did the TB's?

bluesilver82

nice. I going to follow this one and see how it pans out.

I'm Batman

Very cool. Is there any advantage to the Offy cross-ram over a fully-ported Cross-Fire manifold?

comp

simpson36

Lots of questions . . lets' see . .

The TBs have full 2.375" throttle plates. Together they will flow over 1,000 CFM

I make the TBs. I call them UltraMods. Here is the whole family:


The best feature is that they all have fully functional balance ports, so they can be set up and balanced properly with a manometer.

Other features are sealed stainless steel ball bearings on the shafts, fully functional IAC, all vac ports functional, base gasket surface is machined flat, pods are spaced up a specific amount on machined aluminum spacers.

THe 2.125" UltraMod prototypes went on a crossfire manifold that I ported. This setup is now on a mild 350 and the owner posted back that he has a smooth idle, no dreaded crossfire off-idle stumble and it pulled hard to his red line (didn't say what that was).

Here is his setup as it left my workshop:


A second set of 2.125" is just getting finshed up and is going on another interesting alternative manifold project.

I port crossfire manifolds very aggressivley, but there is really no comparison to the Offy. The Offy is huge.

Engine under that Offenhauser is a new small block. 4.155" bore, 3.75" stroke, 6" rods, long tube headers. Targets are 500HP and 6,500 RPM

To give an idea of where this project stands, I am ordering the materials for the adapters and fuel system today.

simpson36

Sorry, forgot to answer one question;

I did make a new crossfire top plate for another project, but I would not even THINK about doing away with this beautiful Offy lid! I've been wanting to play with an Offenhauser cross ram for a long time. This is my dream project and the perfect home for the MOATB! (Mother Of All Throttle Bodies)

I will be making custom adapter plates, custom stainless steel linkage and brackets (inlcuding cruise control and TV cable). The owner wants the adapters blasted hard to simulate the look of a casting to blend in somewhat with the Offy lid. Awesome idea!

These are the first prototype 2.375" TBs and will have 90lb GM injectors in the pods. It took months to find real 90lb injectors for the three projects I have going.

I am also doing the fuel system for this project from scratch.

simpson36

This is not a lot to post, but I thought I might share some interestig info.

I am not satified with the typical 'fuel line' sold in coils by Jegs, Summit, etc. Once the aluminum tubing has been coiled, it is very difficult to get it perfectly straight again.

The typical tubing sold as 'fuel line' is grade 3003 with a 0 temper for bending and flaring. I am using industrial 5052-0 available in straight lengths. This tubing is 3 to 4 times the cost of the typical coiled tubing, but has superior strength and corrosion resistance. It is ASTM certified for hydraulic service.

The owner of this project has in mind to polish everything polishable on the manifold. I am also not satisfied with the quality of the bends on aluminum tube that I get from my previous bender, which I use for steel brake and fuel lines that are never seen, let alone polished, so I purchaed a new bender for this project

Here is the quality produced by the new bender on this high spec tubing, along with a quick and dirty polish of a test piece.



Needless to say, I am very satisfied with the results. I will post pictures soon on the progress on the fuel system fab.

VegasJen

not trying to poke fun but you have obviously never seen that abomination that is the "cease fire" manifold. just a horrible manifold with no potential in it.

simpson36

clutchdust,

The crossfire manifold has problem areas, but with a good port, it is a good street manifold with excellent low end and midrange. There is a restriction that limits it's use for a 350 or bigger motor that has high RPM capabilities, but that's where the Offy comes in.

Please don't hijack this Offy thread. I'll post some crossfire porting pics here, but if you want to talk about how bad the 'Ceasefire' is, lets start a new thread on that.


What I do a little different is get rid of the EGR altogether, including the rear hump and then plate off the holes for smooth flow:



You can see in this pic that I cut the ports on a mill.



Here is the final smooth back. The circled areas are where I went in deep to remove bad casting flash, which is typical of the '84

simpson36

Here is the final mock-up.

Oddly, the fuel return was the challenging part.

Note the use of the original throttle, cruise and TV brackets from the crossfire. Fuel supply and retun tie-ins are fairly close to the original location of the stock steel lines so hookup should be no problemo.

Taken together, those items practically make this a plug-and-play swap. All you need is the TB mounting plates, linkage and bracket mounts and you're ready to rock.

I'm satisfied with the design, so the fun part is over and it's just down to making alumunim chips now. The 'work' part. I'll post more pics as the fabrication and assembly progress.



The return block will not have two exits, these are alternate positions for the tie-in. One points directly off the lid and there is a valve cover out there somewhere, so I provided and alternate port just in case.

The white paper represents aluminum plates that will be added to mount the throttle brackets and the return block. Also the fuel rail will mount on a heavy stud, although that is not shown in this mock-up.




Once this project is done and shipped, I am moving immediately into a third similar project, but with a different manifold.

MN-Brent

Your work is amazing.

Black 82

Nice work on those lines. What kind of bender are you using?

I'm Batman

I've seen threads with extreme porting to open them up, which is why I was curious about the differences.

Inquiring minds want to know.

VegasJen

simpson, not trying to hijack your thread. your manifold looks great. i've been wondering why no-one has done this before considering how many L83s there are out there.
so tell me, with just stock TBs, how much would the offy manifold make top end?

MN-Brent

Clutchdust
Swing over to the CFI Vault forum for a good read. Porting CFI manifolds seems pretty commonplace, along with all the other goodies:

-TBs bushed and enlarged
-alternate manifolds
-fuel pump upgrades
-cam choices
-head choices
-exhaust
-CPUs and all that programming crap

Since the stock system has many restriction points, you cant mod just one piece and hope for a miracle in power. Similar to an L48 I suppose.

I'll get off the soap box now....

simpson36

Black 82

The bender is an Imperial. I already have two other benders, but they weren't doing a good enough job on the high spec aluminum tube. I'm pretty **** about appearance, and the whole fuel system is going to be polished, so the bends have to look good. I'll get the model number of the bender and post it.

I also bought a new flaring tool, but I'm going to have to modify it to get the smaller bend-to-flare distance I need.

Clutchdust;

Now if you want to see a REAL abomination of a manifold? X-RAM - nothing but an empty aluminum box bolted to a regular single plane single quad manifold. It's the most idiotic piece of automotive equipment I've ever seen.

OK, back on topic:

Stock TBs on an Offy would be an extremely bad mismatch. I would not even consider it. Crossfire TBs are from a 4 banger. The only TBs GM had at the time. Even a ported crossfire manifold can use 2" and 2.125"

The targets on this project are 500 HP and 6,500 RPM. I think I can get there with 23lb of fuel presure to the 90lb injectors I'll be using. Man, those things are hard to find! My BIG TB project went on ice for almost two months while we searched for 90lb injectors for it. Between the owner of BIG TB and myself we were eventually able to score 6 of the 90lb injectors.
2 for BIG TB, 2 for this Offy project and 2 extra . . . no way, don't even ask.