Boostec Supercharger Information

[O-Gauge Steamer]

68mm Throttle Body on the way from F&B.
http://www.fbthrottlebodies.com/

Per F&B recommendation, I have ran the vacuum tests to determine what, if any, restriction were in the ntake path. My homegrown CAI has less than 1"Hg of residual vacuum at WOT which says, as of now, no restriction to the flow. The compressor intake manifold, on the other hand, showed a 4"Hg residual. This says that the stock throttle body is not, as Sprintex has claimed, large enough to properly feed the compressor. The 68mm will remove this restriction. It was a debate, 68mm or 70mm as F&B make both along with a 62mm for stock engines. I went 68mm as, IMO, there is not enough material at the mounting flange of the compressor intake manifold to adequately support the 70mm TB. Given that the cost is exactly the same, the decision was one of practicality.

Based upon thier experience and dyno runes, F&B recommends the largest possible TB that can be bolted to the compressor intake. Reductions in full boost pressure discharge temperatures have been reported by removing the restriction on the compressor. Nothing spectacular, but every degree helps.

The TB is a new part from billet. Which explains the cost. If you are looking for a cheap solution, F&B is not the place to go. If you are looking for a high quality, new part...

What will be interesting is to see if the CAI still passes muster once the 68mm is in place. What is driving the change is the Kid coming home. I will finally have some help to do the work. Part of this change is insulating the discharge side manifold, adding a header blanket (do not like header wrap as I have seen too many cracked headers from them) and a retune to accomodate the new TB. I expect the retune to be minor for the TB, but we do have to finish the timing.

F&B, as I have pointed out in other threads, works with Kenne Bell on thier SC kits. Bruce at F&B (nice guy, very knowledgeable) has asked me to pay atttention to the maximum boost I get out of the system. Based upon the 4"Hg of residual, he is of the opinion that there may be nearly another lb of boost lurking.

Will let those that are honestly interested know how it comes out. All of the parts should be on hand by 7 August. The TB is being built today.

F&B Vacuum test:
Using a quality vacuum gauge, measure the residual vacuum in the system starting with the tube from the air filter to the TB. The goal is 1"Hg or less at WOT. If vacuum greater than 1"Hg is found, remove the filter and try again. Vacuum going to the goal indicates a filter flow issue, higher than goal indicates restriction in the plumbing.

With the filter and it's plumbing removed, measure the vacuum level in the intake manifold at WOT. Residual above 1"Hg indicates an undersized TB.

For stock and near stock engines, the factory system should test out as good. For strokers and forced induction, the stock system will most likely prove out insufficient to the need.

For my testing, I used a Dwyer Magnehelic® Differential Pressure Gage. The results of which I had to convert to "inches of Mercury" as it is an "inches of Water" gauge. Given the low levels expected, I elected to use the more sensitve of my diagnostic equipment. An overkill, to be sure...

 

[CobraMarty]

You will have to port the compressor intake manifold to match the larger 68mm and can port a little lower into the intake to open it up a bit. There is a bottle neck further down. Only limited by the thickness of the casting.

Check the linkage where the throttle cable and cruise control connect. These need to be sized correctly for easy movement of the cables on the posts.

With your OBD gauge, what is your MAP reading at WOT?

 

[CobraMarty]

This pic shows some of the porting necessary. The deeper area to also port is the 'throat' just out of view in the pic about 2" down.

 

[MoparManiac]

Yeah looking at the picture, it definitely does not look round. Maybe it's the angle?

I dunno, but it just doesn't look like it would match up well.

What was your process for matching the intake bore to the TB bore?

 

[MoparManiac]

Before this gets derailed again...

What is the need for a rough surface if you're running a dry manifold?

I thought that a rough surface was only needed if you have an air/fuel mix.

 

[Talyn]

And how is your supercharger system working for you? Oh yeah you don't have one.

What does making a close to round hole have anything to do with if I have a SC or not? I know its not the easiest thing to keep a hole round doing it by hand, but come on.

What is the need for a rough surface if you're running a dry manifold?

I thought that a rough surface was only needed if you have an air/fuel mix.

The opinion on that varies. Some say leave it rough (even this changes 80 grit, 120 grit, etc), some say just short of a polish finish. However, the finish is indeed more important on a wet intake as you don't want the fuel to fall out and stick to the walls.

 

[O-Gauge Steamer]

Mopar,
As I have no idea what you are asking, I can not answer this question. Cobra is on my ignore list...

Intake manifolds for carburetors should be as smooth as possible to reduce "fuel cling" on the walls. Every little nook and cranny will want to hold onto the fuel which is one of the reasons the manifolds are heated. By forcing the fuel into a vapor state (from the droplets the carb drops down the hole...) you get a better chance of a proper burn in the cylinder.

Dry manifolds, on the other hand, do not have any real need to be smoothed past what the casting provides when used on the street. Top Fuel manifolds are, generally speaking, highly polished. Also, the runners tend to be straight shots to the valves.

Nobody here has an engine anywhere near that efficient...

Some might say that polishing the manifold will promote the air flow and whilst I agree that to be true in theory, the practical world is a different place. Look at the typical log manifold used pre-99+. 90 degree bends everywhere. No amount of internal polishing is going to overcome those points. From a Flow Dynamics viewpoint, when a gas or liquid encounters a sharp bend, it "bounces" off of the turn which sets up a high point of turbulance. Inertia has the working fluid wanting to contiune in it's original direction. See Newton...

The log type manifold was originally designed for cost efficiency not engine efficiency. The 99+ manifold with it's shallower curved runners and larger plenum, is a superior design to either the Renix or HO manifolds.

As for my little project Heep, the delivery from JEGS came in incorrect and so I wait for the correct part to arrive. Once everything is on site, I will proceed. To be honest here, my Son will proceed as I am no longer able to do the work.

To JEGS credit, when I called them to let them know I got two of one item instead of one of two items, they ponied up with the shipment of the correct part, at thier expense, along with calling FedX to come to the house and pick up the wrong part for return, also at thier expense.

I have been dealing with JEGS since around '65 and they are, usually, on thier game. This is the first false shipment I have ever had, so.... Pretty good track record. Jegs and Speedway are my two first choices for performance parts.

All in all, American design for intake manifolds (exhaust too for that matter) has always been for cost. Until the CAFE standards came into being which forced Detroit to join the rest of the world. For instance, in '76 I built a 347cuin small block Ford and ran an intake manifold from Italy on it. Made by a little company called Weber. It used 4 each 48 DCOE 2 barrel carbs layed down so that the drivers side carbs sat over the passenger side valve cover. Nearly straight run to the valve. Not quite a straight shot, but you could see the valve with the carb off the manifold. Just sayin...

Point is, that manifold had been originally designed in the mid '60s when the typical American intake had a sloppy 2 barrel perched atop a chunk of iron. Zero thoughts to efficiency, just built it as cheap as possible.

Because, as long as the thing started and ran, the average American just did not care...

Only the Hot Rodders (at the time) cared and I grew up in a family full of those fools.

In Europe, it was a different story. Post War Europe had fuel rationing and the Governments put the original "gas guzzler" taxes into place. Some Countries have limits on displacement. A 4.0L is considered HUGE in Europe where here... In Europe, cars run around with sub 2 litre engines all day. My Mercedes had a 4.5 Litre V8 in it. With, I might add, an 70mm Throttle Body...

There are 600cc Cars running around Europe... Can you imgine driving a three cylinder, 600cc pocket car?

 

[O-Gauge Steamer]

What part of "do not see the comment" do you not understand?

I stay off of your threads, have a bit of courtesy and stay off of mine. Both of you guys are on the list so just bugger off will you?


For those that are actually interested, the replacement throttle body shipped out from San Diego (F&B) yesterday via Proprity Mail. I expect to see it by weeks end along with the Lava Mat that did not ship from JEGS.

Photos will follow.

 

[Talyn]

I know where the Lava mat is going, but what are you using for a header blanket?

 

[CobraMarty]

No worries there. Cobra's an ER Physician. Physician heal thyself.



Cherokeeforum seems like a good fit. Lots of handshakes and handjobs there.

And that is acceptable.

TY yan I will take care of myself.

There is a line with federal cyber stalking laws, is this stepping over?

 

[ChiXJeff]

Make that at least 4 mods and/or admins.

 

[5-90]

What does making a close to round hole have anything to do with if I have a SC or not? I know its not the easiest thing to keep a hole round doing it by hand, but come on.


The opinion on that varies. Some say leave it rough (even this changes 80 grit, 120 grit, etc), some say just short of a polish finish. However, the finish is indeed more important on a wet intake as you don't want the fuel to fall out and stick to the walls.

I'd learned it the other way - with a "dry" manifold, you want a good surface finish to promote laminar airflow and improve flow efficiency.

With a "wet" manifold, you actually want to leave the surface a bit rough through the manifold - about 120gr or so - to promote the "edge tumble" to help keep the fuel in suspension.

That explanation makes sense to me - do I have it wrong?

 

[5-90]

I know I left off with a question in my previous post - if anyone has a definitive answer, would you please hit me backchannel? If you have a citable source, I'd appreciate that as well (what I learned before was "OJT" - and I haven't seen anything I can recall in literature. Doesn't mean it's not there, tho...)

However, since you just had to get going again, I've made good on what I said earlier. There's actual useful tech information left in this thread, so I'm not going to delete it.

I am going to close it, at least temporarily. If enough people ask nicely enough, it may be reopened. If anyone decides to go over my head, I only ask that:
- You include me in the discussion so I have the opportunity to defend my actions, or
- Whoever you go to comes back to me so I can explain myself before they take action.

Red Cards have already gone out to the visibly deserving.

I don't know what it is that makes everyone get so childish in threads like this, but KNOCK IT OFF As I've said before, moderation can be difficult enough without people getting willfully fractious and stupid. I am pleased to do it to give something back - but don't make the job any more difficult than it already is. I've displayed a great deal of patience, I think. Warnings were issued. People got stupid anyhow.

I don't make threats - I issue warnings. Ignore them at your own peril. (Just ask my kids. They're not threats - they're promises.)

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