Intake for FiTech

[det0326 179]

I am going to purchase a TBI system either in the group buy or other wise and am getting ready to buy the intake for it. I was wondering if any body knows if this one http://www.ebay.com/itm/191563495318?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT would  work as for as enough clearance under the hood. I think it had in the description that it is 5.750 inches high. The TBI and filter will add another 6 or 7 inches probably at least thats getting pretty tall. If anybody could shed some light on this it would be greatly appreciated. This is going on a 351w.

 

Thanks Dave  

[Shep69 149]

The rpm air gaps are to high and won't fit on s 69 unless you run a drop base air cleaner. If you have a shaker forget it . I'm running a rpm and even that's a bit high .

[det0326 179]

thanks Shep that's what I was afraid of, do you know of a good dual plane intake that sits lower.  I have AFR heads and they recommend this intake but if there is one that would work well with the FiTech system and sit lower that would be great.

 

Dave

[Shep69 149]

thanks Shep that's what I was afraid of, do you know of a good dual plane intake that sits lower.  I have AFR heads and they recommend this intake but if there is one that would work well with the FiTech system and sit lower that would be great.

 

Dave

Hi Dave . I'm not sure what would be the best intake for your application. Maybe some of the other guys may be able to give you some ideas. I have heard that some guys say that the FiTech systems don't work that well on the duel plane manifolds and others say it's ok. I can't see an issue as it's just a electronic carby basically. I will be putting one of my duel plane so we will see what happens.

[fordguy69 24]

I have an Edelbrock RPM Air Gap with my FiTech.  It works fine.

 

The throttle body is the same height as a Holley carb.

 

Can't help with the hood clearance question because my set up is not stock. 

[det0326 179]

Thanks Shep I have read that also that the dual plane may cause an idle problem but a lot of the guys on here say they have no problem with dual plane so i would take there word over the web. LOL  I appreciate your help. thanks

 

 

 

fordguy you say yours is not stock did you modify the engine mounts to lower the engine or modify the hood for more clearance? Is there a way you could  get a measurement from the front intake gasket surface to the top of the throttle body.  Don't go to any trouble tho like taking stuff off to get at it but if you could get a rough estimate that would be great.

 

Dave   

[fordguy69 24]

fordguy you say yours is not stock did you modify the engine mounts to lower the engine or modify the hood for more clearance? Is there a way you could  get a measurement from the front intake gasket surface to the top of the throttle body.  Don't go to any trouble tho like taking stuff off to get at it but if you could get a rough estimate that would be great.

 

Dave   

 Dave, my measurements aren't going to help you much. I have a 460 big block in mine with mounts that lower the engine and move it forward.  I still had to cut a hole in the hood though. 

 

If you are going to use an Edelbrock intake, they have carb height measurements and such in their catalog.  And I do know that the FiTech throttle body is nearly identical to a Holley carb in height.  So maybe you could put together a pretty close estimate. 

 

That's why I can't help anybody with hood clearance issues or shaker issues!  Sorry I couldn't be more help.

 

Bill

[JD08 42]

If some people say there's a problem with a dual plane and nobody says there's a problem with single plane, why chance it?

 

IIRC, the throttle body units work better with a single plenum, but adding a spacer or trimming the center divider of a dual plane will do that.

I suspect the dual planes were overcoming a weakness of a carb's low fuel pressure creating the proper atomization. 

[det0326 179]

fordguy  a 460 in a mustang.... lucky you.    Yes those measurements wouldn't help but thanks for the info.

 

 

JD08   My only concern with the dual plane and single plane is that with a single plane you sacrifice low end power and low end power  is what I want and it is also suitable for my setup, heads, cam and etc.  My biggest concern tho with either is to make sure it fits under the hood. After doing farther research tho I don't think the Air Gap will fit without modification. 

 

 

 

Dave

[JD08 42]

The single/dual plane argument is for carbs. It apparently doesn't apply to FI because of the adjustments the computer can make.

[shaun071 62]

The single/dual plane argument is for carbs. It apparently doesn't apply to FI because of the adjustments the computer can make.

I'm no expert, but given the fuel is entering the intake in the same place as a carb, I think the dual plane/ single plane argument is valid. Yes the computer has better control, but at low revs your fuel/air mix is going through the intake same as a carbed system with all the poor atomisation issues etc if your engine doesn't need a single plane. A tbi system will probably mask the problem to some degree but it will still be there. A multipoint system where the injectors are at the port you only have air running through the manifold so you don't have issues with poor atomisation at low air speeds. Just my 2c.

[det0326 179]

yes Shaun I think you are right.  You can compare the specs of the two and the single plane will have the power band always about 2500-3000 rpm's higher than the dual plane.  I think I need to go with dual plane with the setup that I have. I was basically wondering if the Air Gap would fit under the hood but it seems from others that it will take modifications to make it work. The performer RPM may work under the hood OK but some say it will be very close. The performer will definitely work I am told. Thanks everyone for all the info.  

 

 

 

 

 

Dave 

[1969_Mach1 333]

I was only able to get an RPM Air Gap to fit my 69 Mach 1 with a 351W with the following air cleaner combination.  3" tall 14 inch dia. filter, Moroso air cleaner lid and base with the base modified to drop 1-1/2".  This gave me about 5/8" hood to air cleaner clearance.  The clearance between the air cleaner lid and the choke horn was only about 3/8".  That was too small and restricted air flow so I ultimately swapped out the intake for a Torker II and a 4-hole to open 1" tall tapered spacer below the carb.

 

The RPM Air Gap might fit with EFI since there is no choke horn to interfere with a drop base air cleaner.  As long as you are not using a shaker hood.  I would carefully mock it up and not bolt it down.  Then, if it doesn't fit exchange it for something different.

[JD08 42]

If FI worked the same as a carb, why switch? The power band specs you're finding are for carbs, not FI.

 

There is a significant difference between fuel under 7 psi going through a jet constantly and fuel at 59 psi going through a computer controlled injector.

 

The best description I can find is by a poster named Dragula in this thread.

http://board.moparts.org/ubbthreads/ubbthreads.php/topics/701872/open-vs-dual-plane-intake-for-fi.html

[1969_Mach1 333]

True that you cannot compare TBI or port FI to a carb.  A carb relies on the signals inside the intake manifold to operate which are stronger on dual plane intakes than single plane intakes.  EFI doesn't operate based on those signals.  But keep in mind that intake runner lengths and cross section profiles also contribute to the RPM range of an intake manifold.  Also, on single plane intakes, at low speeds, the air/fuel charge inside the intake gets more diluted with exhaust gases from valve overlap than on dual plane intakes.  Another reason why dual plane intakes operate better at low speeds than single pane intakes.

 

On the other side since single plane intakes usually have more even air/fuel distribution to each cylinder I can see why some posts state that FiTech systems operate better on single plane intakes.  On a dual plane if there is any difference in signal strength from side to side a carburetor can compensate for that where as TBI of port EFI cannot. 

 

The old Holley Street Dominator intakes for 351W's use to make a lot of low and mid range power for a single plane intake.  I don't know how they compare to today's single and dual plane intakes.

[MikeStang 247]

Im Running a Vic Jr. On my 408 With AFR Heads and drop base air Cleaner...It fits but just barley.

Your not going to give up that much Torque with the Single Plane Intake over the dual plane, you probably wont even notice it

[1969_Mach1 333]

On a large 408 cubic inch motor it's probably not so noticeable.  I am not promoting one type over the other because they both have their place.  But on mild built smaller carbureted motors, 351 and smaller, I have noticed an obvious low end performance difference between single and dual plane intakes.  Especially comparing a Victor Jr. to something like a Performer RPM, RPM Air Gap, or Weiand Stealth. 

 

Don't get me wrong.  I am a bit old school and like the more even A/F distribution of a single plane intake.  Especially when looking at how the dual plane runners need to be routed on small block Fords.  I compromised and lost a little bottom end with a Torker II over a Performer RPM or Weiand Stealth.  But the Torker II fits well even with a 1" tall tapered spacer and my spark plugs all look the same.  The spark plugs never looked the same with a Performer RPM.  And with a Performer RPM or Weiand Stealth the idle rhythm pattern always seemed odd like there were lean misfires occurring which I don't have with a single plane intake.

 

This is merely an educated guess.  But, considering the nature of how TBI operates compared to a carb, I think with TBI there wouldn't be as noticeable of a low end performance loss with a single plane over a dual plane manifold.  It would be nice if a member here would have some real world comparisons on this.

[det0326 179]

Yes1969-Mach1, real world experience is what I was hoping for but I guess this system is so new it hasn't been tested that much. I did some more digging in the Fitech web site, in there FAQ's section they did address that question single or dual plane and said that is a question to ask your engine builder that there system would run fine with either but is better to run which every one is compatible with your build. So if I don't change my mind I think I will go with the Performer RPM.

 

 

Dave

[shaun071 62]

its an interesting topic and worth starting its own thread. Because Fitech is so new maybe people with other tbi systems could share their experiences. Also getting a range of vehicle use would be great too. What works for someone who just drag races their car would be different to somebody using tbi as a carb replacement on a daily driver.

[det0326 179]

well guys I got the performer rpm today and it is a nice piece if that counts for any thing.  It may not fit under the hood without mod. but I now own it.

Thanks for all the info and help.

 

Dave

[Mach1 Driver 563]

I thought I would move some information over from my thread "Height of 2100 2V" and condense it.

351w Intake Manifolds

                                               Power Band                                        Carb Height   Clearance                              Clearance

                                                     RPM       Satin    Polished   Black       CH†           to hood           port size      to distributor

Stock Manifold                                 -              -             -              -          4.00

Edelbrock Performer 351w      Idle-5500     2181      21811    21813      4.00            1.874(a)

Edelbrock Performer RPM     1500-6500    7181      71811                     4.80            1.074(a)     1.90h x 1.08w          c)

Edelbrock Rpm Air Gap         1500-6500    7581      75814                     5.75            0.124(a)

Weiand (Holly) Stealth           1500-6800    8023                                    4.715(b)      1.159(b)      1.82h x 1.05w

 

(a) The 69 Mach1 hood scoop has bolts that stick down 1/2". Clearances are without hood scoop.

(b) The carb pad is angled with an average height of (4.37 front+5.06 back)/2=4.715". I don't know what net effect is for clearances front and back but "1969 Mach1" says the 8023 fits well with the stock air cleaner.

 c) The carb pad has been moved forward and the stock or 14" aftermarket air cleaner will hit an aftermarket distributor with a large distributor cap per "1969 Mach1". He says there are no clearance issues with the Weiand 8023. Note that the bottom of the stock air cleaner is already embossed to clear the distributor cap and wires.

 

Since I have a stock distributor I may go with Edelbrock's 7181 since I'm going to use their heads, and the Edelbrock 7181 has slightly larger ports.      

[det0326 179]

Thanks Mach1Driver   good information.

 

Dave