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Injector Stack vs. SM Intake #847902
11/07/10 11:24 AM
11/07/10 11:24 AM
Joined: Dec 2005
Posts: 252
St.Louis, Mo.
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mokid Offline OP
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I have a chance to buy a injector tube type intake from indy the type that goes on sprint motors, But I currently run a CFE S.M intake with a single Dominator can anyone give me pros and cons of injected over carb?

Re: Injector Stack vs. SM Intake [Re: mokid] #847903
11/07/10 12:44 PM
11/07/10 12:44 PM
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St. Paul , Mn.
tubtar Offline
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This is just heresay and opinion......I have no experience with injected and stack set up other than almost buying one for a SBC years ago.
I have seen them running on a serious street motor , but it idled around 2,000 and I was told that it isn't very tractable through low to mid r.p.m. , but made a right fine on - off switch.
They are geared for W.O.T. use primarily , though tuning will obviously make them work through a set range i.e. road racing.
Getting the complete set up would cost more for injected if buying new.
And the show and tell factor is off the charts.
I thought about plumbing one for EFI , which would clear up most driveability issues.
I don't know that there would be a significant H.P. increase over a carb and sheetmetal intake unless your motor could swallow more air than the carb will allow.

Re: Injector Stack vs. SM Intake [Re: tubtar] #847904
11/07/10 01:19 PM
11/07/10 01:19 PM
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St.Louis, Mo.
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mokid Offline OP
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Set up sits on a W7 small block I believe its a 440 cu in car ran inthe low 8's in a 3200 lb conquest, The entire motor is for sale, Very sad story a true mopar racer died of cancer his wife and best friend now are selling everything including Hemi Alum block, a complete 572 hemi block that has 440 heads, several race small blocks, also cars a 67 Barracuda just out of the body shop, a 65 Barracuda full tube chassis running a 440 with a pro charger best of everthing, never got to race car before he died, also a 67 cornet show quality with a Alumn Hemi never run. If any interested parties please let me know.

Re: Injector Stack vs. SM Intake [Re: mokid] #847905
11/07/10 02:15 PM
11/07/10 02:15 PM
Joined: Jan 2003
Posts: 684
St. Charles, MO.
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Slingshot383 Offline
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Stack injection on alcohol will make more power than a carb on alcohol, and if you are starting from scratch, the costs is comparable. If the system came of a sprint car motor with W-7 heads, it will not bolt straight on a set of 440 heads.


1994 Undercover Chassis 125" altered stack injected big block, soon blown and injected Member of The Torque and Recoil Club
Re: Injector Stack vs. SM Intake [Re: Slingshot383] #847906
11/07/10 02:51 PM
11/07/10 02:51 PM
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St.Louis, Mo.
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mokid Offline OP
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No it's on a 440 cu in W7 head motor mine is a W8

Re: Injector Stack vs. SM Intake [Re: mokid] #847907
11/07/10 07:55 PM
11/07/10 07:55 PM
Joined: Oct 2007
Posts: 4,219
New York
polyspheric Offline
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The IR throttles have to be really huge to beat a carbureted plenum manifold.


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Re: Injector Stack vs. SM Intake [Re: polyspheric] #847908
11/07/10 08:54 PM
11/07/10 08:54 PM
Joined: Nov 2009
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St. Paul , Mn.
tubtar Offline
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Quote:

The IR throttles have to be really huge to beat a carbureted plenum manifold.




This kind of formed my opinion........they seem to start at 2 1/8" dia and go up from there on small block set ups I have seen........telling me that they will allow huge amounts of air in.
And if you don't have the arrangement that requires this , a carb would be a better choice.
Again.....purely guess work from my corner.
But it seems to work on paper.

Re: Injector Stack vs. SM Intake [Re: tubtar] #847909
11/08/10 12:08 AM
11/08/10 12:08 AM
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Posts: 4,219
New York
polyspheric Offline
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That's not very big. Crower used 2.90" stacks on 427" BBC 40 years ago.


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Re: Injector Stack vs. SM Intake [Re: polyspheric] #847910
11/08/10 12:50 AM
11/08/10 12:50 AM
Joined: Feb 2004
Posts: 1,093
Long Beach, CA
Mike Swann Offline
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Quote:

That's not very big. Crower used 2.90" stacks on 427" BBC 40 years ago.




CanAm McLarens in the late 60's


8.30's @3400 lbs
Re: Injector Stack vs. SM Intake [Re: mokid] #847911
11/08/10 09:57 AM
11/08/10 09:57 AM
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Posts: 572
Shelbyville, TN USA
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40ford Offline
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Individual runner injectors(AKA Hilborn and others) have advantages and disadvantages compared to a standard carb.

The IRs don't idle well and don't accelerate well off idle----they don't have an acceleration pump as carbs.

But if you are going to keep the RPMs above 4000, the throttle response is much better than a carb. A carb depends on engine vacuum to flow fuel---the IR flows fuel based on the mechanical metering block so fuel flow is instanteous, and the nozzles are very close to the valve. Throttle response is the reason sprint cars use them with great success.

In the past, IRs suffered compared to large plenium carb setups because of the smaller runner size---but this has been corrected with later IRs with runner size of over 3" in diameter. These large runner IRs allow RPMs as high as you are willing to run with good HP AND you can taylor each cylinder to max fuel/air mixture. You don't have to worry about rich/lean cylinders.

There is a learning curve with IRs---don't try to shortcut it!

Re: Injector Stack vs. SM Intake [Re: 40ford] #847912
11/08/10 02:10 PM
11/08/10 02:10 PM
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St. Charles, MO.
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Slingshot383 Offline
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The Indy 8-Stack is a 2.90" throttle bore, and Engler Machine and tool can make them much larger than that. A properly set up mechanical fuel injection unit will work at lower rpm's than 4000, and will also have a clean idle.


1994 Undercover Chassis 125" altered stack injected big block, soon blown and injected Member of The Torque and Recoil Club
Re: Injector Stack vs. SM Intake [Re: Slingshot383] #847913
11/08/10 06:25 PM
11/08/10 06:25 PM
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1 Offline
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Cincinnati, Ohio
Quote:

The Indy 8-Stack is a 2.90" throttle bore, and Engler Machine and tool can make them much larger than that. A properly set up mechanical fuel injection unit will work at lower rpm's than 4000, and will also have a clean idle.




I agree with the last 2 posters.

I have run 2 different stack injections and have out run all carbs.

I could see driving them on the street, no problem. I even used my N2O system to prime the motor to start,one man job.

Re: Injector Stack vs. SM Intake [Re: 40ford] #847914
11/08/10 08:46 PM
11/08/10 08:46 PM
Joined: Oct 2007
Posts: 4,219
New York
polyspheric Offline
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The IRs don't idle well and don't accelerate well off idle----they don't have an acceleration pump as carbs.

Backward.


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Re: Injector Stack vs. SM Intake [Re: polyspheric] #847915
11/08/10 09:33 PM
11/08/10 09:33 PM
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:

The IRs don't idle well and don't accelerate well off idle----they don't have an acceleration pump as carbs.

Backward.




BS Injection is crisper than carbs. Your talking to someone who has done a ton of tuning. I'm a expert stack injection user, I can make em sing loudly.

Last edited by Challenger 1; 11/08/10 09:38 PM.
Re: Injector Stack vs. SM Intake [Re: Challenger 1] #847916
11/09/10 02:45 AM
11/09/10 02:45 AM
Joined: Oct 2007
Posts: 4,219
New York
polyspheric Offline
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So, by BS - you mean I'm right.


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Re: Injector Stack vs. SM Intake [Re: polyspheric] #847917
11/09/10 08:52 AM
11/09/10 08:52 AM
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1 Offline
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Quote:

So, by BS - you mean I'm right.




Sorry I was confused, I thought that was your quote.

Re: Injector Stack vs. SM Intake [Re: Challenger 1] #847918
11/09/10 10:07 AM
11/09/10 10:07 AM
Joined: Mar 2007
Posts: 572
Shelbyville, TN USA
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40ford Offline
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Maybe I am wrong----maybe you can get IRs to idle well-----or maybe our little pipsqueak engine is too small----we just don't concern ourselves with idle or lower RPMs----as long as it is smooth at staging and throughout the RPM range, we are happy.

Been wrong before, will be wrong before the end of the day!

Re: Injector Stack vs. SM Intake [Re: 40ford] #847919
11/09/10 10:47 AM
11/09/10 10:47 AM
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Kinsler split shafts allow a good idle.
A even idle is really important so all plugs are heated the same before the run.

Re: Injector Stack vs. SM Intake [Re: 40ford] #847920
11/09/10 10:52 AM
11/09/10 10:52 AM
Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
B G Racing Offline
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Eighty Four, PA
Mechanical stack injection is finickie to adjust.You have a high speed bypass and idle bypass to control excessive fuel,a main jet or pill controls the fuel feed,a slotted valve that increases the slot size is the throttle control.All the bypass and main feeds are controlled by pill size ,similar to jets.Many manufactures have modified these systems for better throttle characteristics.We just adjust for the best idle and maximum wide open throttle performance.We don't recommend mechanical stack injection for the street unless it is set up with a EFI system.

Re: Injector Stack vs. SM Intake [Re: mokid] #847921
11/09/10 11:42 AM
11/09/10 11:42 AM
Joined: Feb 2004
Posts: 1,093
Long Beach, CA
Mike Swann Offline
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Ive seen guys do conversions where they have EFI injectors on the underside of the stacks , connect MAP to all of the stacks with small tubes on the outside to a miniature manifold and a TPS on one throttle shaft. Works really nice for the street.


8.30's @3400 lbs
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