Porting the Edelbrock Pro Flow XT 7137

Discussion in 'Engine: Repairs , Modifications ,trouble shooting ' started by ASE Doc, Nov 22, 2017.

  1. ASE Doc

    ASE Doc Member

    I'm starting this thread here to talk about the Pro Flow XT for small block chevy. I plan on installing it on a 355 next summer. I chose the XT because of all the performance EFI intake options on the market today, I think the XT shows the most overall potential for combining top end power and midrange torque. While the overall design of the XT is good, the weakness I see is the small runner exits. Mounting it on cyl heads that are port matched to a felpro 1205 gasket(2.09 x 1.28) will leave alot of material inside the gasket openings all the way around each intake port. This could be a pretty big choke point on heads that flow well. My heads are ported Trickflow twisted wedge G2s that flow 270cfm.

    I spoke with Eddy tech just to get their thoughts on it. The guy told me that the small runner exit is intended to increase velocity in the flow range of a street driven engine. That makes since except that if the head's intake port is considerably larger than the runner exit, that velocity is going to drop off hard right where it needs to be strongest for fuel atomization. When I brought up extrude honing to smooth the interior casting, I was also told that the rough casting is there to encourage swirl and tumble of the air through the runners. Now maybe I have learned this wrong over the decades that I've done this stuff but I've become pretty sure that the tumble and swirl needs to take place starting at the back of the intake valve and into the chamber. Swirl and tumble in the runners sounds alot like flow killing turbulence.

    At any rate, I still plan to work this unit over before it goes on. After pricing extrude honing, I'm thinking of going with my other option of having the top of the plenum cut off and hand finishing the runners and runner entries, surfacing the plenum. I may even add a small amount of volume to the plenum when it goes back together. It appears that the piece was designed primarily for street use for stock or slightly larger ports. To support my heads and cam and make my power goal of 460hp at about 6,300, I think it will need to flow a little more, even at the cost of a slight bit of throttle response and low end torque. My 3,500 stall converter and gears will help cover the low end side anyway.

    BTW, I'm here to air my ideas as a long time pro mechanic/ hobbiest engine builder. I hope to start a discussion and welcome any and all opinions and feedback on this intake manifold and my ideas for it.

    Sorry, tried to attach some photos of the piece for those unfamiliar with it. Seems my photos are too large.

    Again, this is the Edelbrock Pro Flow XT EFI tunnel ram P/N 7137.
     
  2. ASE Doc

    ASE Doc Member

    I know that folks will want the details of the build. It is a 10.2:1 355 with 6" connecting rods. The heads are trickflow twisted wedge G2 with 190 as cast ports, ported to 195. They flowed 257 as cast and now flow 270 @.600. The cam is the TPIS ZZX 240/240 @ .050 (292/292) .560/.560 lift with my 1.5 rockers. 112 LSA, 108 ICL, IC @ 74 degrees ABDC. The spring package is set up for 6,500. The car is a 3,400lb 87 Camaro. 700R4 and 3.23 rear gears.
     
  3. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    a great deal of the info you may want can be calculated after carefully measuring the intake port and runner length and cross sectional areas.(remember its not the intake port gasket cross sectional opening, cross sectional area, its the smallest part of the port cross sectional area and valve throat areas that limit port flow rates)
    if as an example we selected a port with about a 2 sq inch cross sectional area, you'll find max torque on a 350 will fall near 4000-rpm and port stall near 6000-rpm thus it makes sense to match the cam timing and lift/duration and the drive train gearing to match the rpm range,power curve and port flow.
    or put a bit differently, theres no sense in selecting a cam designed to operate well at 7600 rpm if you port stalls at 6300 rpm


    [​IMG]
    [​IMG]
    http://users.erols.com/srweiss/calccsa.htm

    http://users.erols.com/srweiss/calcplv.htm

    http://users.erols.com/srweiss/calchpaf.htm


    http://www.wallaceracing.com/chokepoint.php

    http://www.rbracing-rsr.com/runnertorquecalc.html
    [​IMG]
    [​IMG]
    [​IMG]
    http://www.walmart.com/ip/Texas-Instruments-TI-30X-IIS-Scientific-Calculator/1535939
    http://www.summitracing.com/parts/cca-5605/overview/
    related info, that you might need

    http://garage.grumpysperformance.co...heads-for-small-block-chevys.3293/#post-26213

    http://garage.grumpysperformance.com/index.php?threads/what-are-these-heads.4702/#post-12742


    http://garage.grumpysperformance.co...-by-step-guide-with-pictures.5378/#post-71848

    http://garage.grumpysperformance.co...ther-efi-intake-manifold-info.431/#post-26322

    http://garage.grumpysperformance.com/index.php?threads/porting-can-help.462/page-3#post-59145

    http://garage.grumpysperformance.co...ads-tuned-intake-turbulence.12998/#post-67611

    Volume (CCs) of Head Gasket

    CCs of Head Gasket = Bore x Bore x 12.87 x Thickness of Head Gasket
    COMMON SBC INTAKE PORTS
    felpro # 1204=Port Size: 1.23" x 1.99"=2.448 sq inches

    felpro # 1205=Port Size: 1.28" x 2.09"=2.67 sq inches

    felpro # 1206=Port Size: 1.34" x 2.21"=2.96 sq inches

    felpro # 1207=Port Size: 1.38" x 2.28"=3.146 sq inches

    felpro # 1209=Port Size: 1.38" x 2.38"=3.28 sq inches

    felpro # 1255 VORTEC=Port Size: 1.08" x 2.16"-2.33 sq inches

    felpro # 1263=Port Size: 1.31" x 2.02"=2.65 sq inches

    felpro # 1266=Port Size: 1.34" x 2.21"=2.96 sq inches

    felpro # 1284 LT1=Port Size: 1.25 x 2.04''=2.55 sq inches

    felpro # 1289 FASTBURN=Port Size: 1.30" x 2.31" 3.00 sq inches

    http://users.erols.com/srweiss/calccsa.htm

    Your RPM computed from your Cross Sectional Area of 1.95
    (the smaller AFR HEADS)
    and Bore of 4.03 and Stroke of 3.75 is 5,569.12 .

    Your RPM computed from your Cross Sectional Area of 2.05
    (the Larger AFR HEADS)

    and Bore of 4.03 and Stroke of 3.75 is 5,854.72 .
    you,ll barely notice the about 300 rpm shift in the power band on the lower part of rpm range but appreciate it much more on the upper edge of that power curve


    heres a chart FROM THE BOOK,HOW TO BUILD BIG-INCH CHEVY SMALL BLOCKS with some common cross sectional port sizes
    (measured at the smallest part of the ports)

    HeadsVsPortFlow.JPG


    USE THE CALCULATORS

    http://www.rbracing-rsr.com/runnertorquecalc.html
    http://www.wallaceracing.com/chokepoint.php
    http://www.wallaceracing.com/header_length.php
    http://www.superchevy.com/how-to/en...-0902-chevy-engine-port-variations-measuring/
    http://www.hotrod.com/articles/choosing-the-right-camshaft/
    http://garage.grumpysperformance.com/index.php?threads/bits-of-383-info.38/
     
    Last edited by a moderator: Dec 13, 2017 at 9:16 AM
  4. Indycars

    Indycars Administrator Staff Member

    Last edited: Nov 22, 2017
  5. Indycars

    Indycars Administrator Staff Member

    Hey Grumpy, I took your cross sectional data and put it into an Excel table. Then I made a JPG graphic file from it.

    HeadsVsPortFlow.JPG
     
  6. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    thank you!
     
  7. ASE Doc

    ASE Doc Member

    Thanks guys for the replies and the information. Grumpy, I see your cyl head list features the TFS twisted wedge first version. My heads are the second version. In fact I waited a year for these heads as TFS was in the process of development when I ordered them back in 1999. These are a little different, with valve angles of 16 degrees intake and 18 degrees exhaust. The intake ports were enlarged to 190cc, the valves to 2.02 and 1.6. They flowed 257 out of the box. I cleaned up the bowls, removing the seat ridge and smoothed the transitions out to the 1205 port entries. After the port work, they flowed right at 270. Pretty decent for 17 year old heads. I pushed the limits on cam selection. Using a dial indicator to measure valve to piston clearance, which came out to .120. In another year or two, when I'm ready to build a bigger cube SBC, I will have the valves and guides refreshed and may revisit the ports with what I've learned since the original job.

    I'm a little disappointed in the XT runner castings. It's such a great design. I wish they at least left enough material in the runners to allow for porting to suit a larger intake port. They will be thin by the time I take them out to the 1205 dimensions. I may end up having to get them welded up to have sufficient material. I'll measure with a caliper to see how they do as I open them up. There's plenty of room for cutting back the injector bosses where they protrude into the runners. I can smooth those out quite a bit.

    I think the ZZX cam will work well with this intake and head combo. The single pattern favors a good flowing intake side. Since I already have it installed in the motor, I've got to give it a try.
     
  8. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    the ZZX from TPIS. 239 int dur.239 ex dur. .559/ .559 lift .. 112 lsa
    the cams power range will be in the 2800 rpm- to about the 6000 rpm range
    and youll want about 10:1 plus compression,
    Id point out that that cam will require... a manual transmission OR A 2800 rpm-3200 rpm stall speed converter on and auto transmission,
    and a 3.54"1-3.73:1 rear gear, and most likely 38lb-42 lb fuel injectors to work at max efficiency.
    given the correct matching components, and a good low restriction tuned exhaust.. well over 450 hp should be fairly easy to exceed

    http://garage.grumpysperformance.com/index.php?threads/porting-can-help.462/page-3#post-59145

    http://garage.grumpysperformance.com/index.php?threads/port-matching-procedure-step-by-step-guide-with-pictures.5378/#post-71848

    http://garage.grumpysperformance.com/index.php?threads/my-current-corvettes-383-combo.430/
     
    Last edited: Nov 29, 2017
  9. ASE Doc

    ASE Doc Member

    Thanks Grumpy. I'm pretty close to your recommendations. I will try to get started on this intake in the next month so I can post some progress photos.
     
  10. ASE Doc

    ASE Doc Member

     
  11. ASE Doc

    ASE Doc Member

    Again, I'll post photos as soon as I can and update as I make progress. With the holidays in full swing and being busy at the shop, time is tight just like money is right now.
     
  12. ASE Doc

    ASE Doc Member

    Here are some photos of the XT before any work is done to it.
     

    Attached Files:

  13. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

  14. ASE Doc

    ASE Doc Member

    That's right Grumpy. This is the way it's shipped from Edelbrock. I will have the top of the plenum cut off to access the runner entries and so that I can finish the plenum interior. Once I'm done with the porting, I'll have the top welded back in place.

    I don't have enough information to accurately calculate the ideal runner csa for my engine combo. Since I am not prepared at this time to get that involved in redesigning the intake, and I don't have enough info to accurately calculate the best csa anyway, I'm just going to do a minor cleanup and smoothing of the runners and plenum. I will improve its fit to the G2 meads and move the torque curve upward around 500 rpm which this 355 should like. I'll save any more involved work on the manifold until I've been back into the heads and have more information.

    You're familiar with the twisted wedge G2s. I'm guessing your porting job is probably a lot more accurate than what I did 16 years ago on these heads of mine. I didn't measure csa after finishing the port work. I know that I did open up the pockets behind the valves flush with the seats. I kept the swirl vanes and I profiled the guide bosses. I also worked on the short side radius to produce the smoothest path I could without getting the walls too thin. I of course also worked the exhaust ports, especially the short side radius. As you said, the G2s have great exhaust flow already. That's why I chose the ZZX to fit these heads. I installed SLP 1 3/4" primary short tube headers to fit the heads and have dual 2 1/2" pipes.

    If I could edit my previous post I would rewrite it to say that the single pattern cam favors the intake side, not a high flowing intake. If I do leave the XT runner a little on the small side, the ZZX will help cover some of this.
     
  15. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    you appear to be doing everything that can reasonably done to improve flow on that basic EFI intake design.


    as always theres options that are always a compromise in some areas,
    especially if your a tool junky and own a mill and a few welders and are more concerned with function than visual appeal, and your willing to test and tune several designs
    I decided to use my mill and welder to custom fabricate a basic stealth ram
    once it was rather extensively ported it made decent power even if it did not look a aesthetically all that pleasing



    hood clearance is an issue as several other factors
    the holley stealth ram base can be modified
    http://garage.grumpysperformance.com/index.php?threads/tuning-a-tunnel-ram-intake.5175/
    ok here, I got my kid to take pics, this is how far the stock hood will close on a stock hood with the stealth ram installed
    [​IMG]
    [​IMG]
    you can even custom fabricate a plenum to gain the required hood clearance too use a stealth ram base.
    pictured below, is one of several of my custom fabricated plenums , I built and tested on a stealth ram base required to gain the required hood clearance

    [​IMG]
    [​IMG]
    COMMON SBC INTAKE PORTS
    felpro # 1204=Port Size: 1.23" x 1.99"=2.448 sq inches

    felpro # 1205=Port Size: 1.28" x 2.09"=2.67 sq inches

    felpro # 1206=Port Size: 1.34" x 2.21"=2.96 sq inches

    felpro # 1207=Port Size: 1.38" x 2.28"=3.146 sq inches

    felpro # 1209=Port Size: 1.38" x 2.38"=3.28 sq inches

    felpro # 1255 VORTEC=Port Size: 1.08" x 2.16"-2.33 sq inches

    felpro # 1263=Port Size: 1.31" x 2.02"=2.65 sq inches

    felpro # 1266=Port Size: 1.34" x 2.21"=2.96 sq inches

    felpro # 1284 LT1=Port Size: 1.25 x 2.04''=2.55 sq inches

    felpro # 1289 FASTBURN=Port Size: 1.30" x 2.31" 3.00 sq inches

    http://users.erols.com/srweiss/calccsa.htm
    [​IMG]
    stealthram base
    [​IMG]
    [​IMG]

    [​IMG]
    related threads
    theres a good deal of related info in the links


    http://garage.grumpysperformance.co...rger-intake-runners-l98-tpi.13785/#post-70716

    http://garage.grumpysperformance.com/index.php?threads/ideal-tpi-build.12203/#post-59272

    http://garage.grumpysperformance.co...st-flow-ratio-and-cam-timing.9725/#post-56700

    http://garage.grumpysperformance.co...8mm-throttle-body-on-your-tpi.290/#post-54181

    http://garage.grumpysperformance.co...sure-hurting-your-combo.495/page-2#post-53630

    http://garage.grumpysperformance.co...ther-efi-intake-manifold-info.431/#post-48733

    http://garage.grumpysperformance.com/index.php?threads/a-well-designed-c4-exhaust.786/#post-46459

    http://garage.grumpysperformance.com/index.php?threads/can-you-get-there-with-tpi.10494/#post-44299

    http://garage.grumpysperformance.co...e-body-coolant-bypass-thing.10544/#post-44875

    http://garage.grumpysperformance.co...ps-on-building-a-tpi-383-c4.10434/#post-43430

    http://garage.grumpysperformance.com/index.php?threads/port-and-runner-math.148/#post-16494

    http://garage.grumpysperformance.co...or-piston-dome-or-port-volume.2077/#post-9049

    http://garage.grumpysperformance.co...e-stock-tpi-engine-components.1509/#post-3459
     
    Last edited: Nov 30, 2017
  16. ASE Doc

    ASE Doc Member

    Thanks Grumpy. I like your work on the Stealth Ram. I thought about that as an option when I considered which intake to go with.

    I think the XT will work well for me. With a little port cleanup, it will work well on my current 355 and the ported G2s with the ZZX cam. It will definitely be a big power gain over the TPI I've been running since 2000. This TPI is about max of what a TPI, short of the First big dog, can be. It is the Superram base, ported to its limit without welding, the TPIS large tube runners, and ported plenum with a 58mm throttle body. It runs pretty well but I just want more. Plus, adding the intake now is one more step in preparation for the next engine. One less part I have to buy. I was going to go ahead and prepare the XT as if it was going on a 383 or 406. Now that I know there is a lot more I can do to make that work its best, once I have the all the dimensions of the intake ports, I'll wait until then to go all out. For now, I'll just do my thing polishing up these runners and streamlining things. Then I'll put it all together and enjoy what should be a 60hp boost with a wider flatter torque curve.

    The XT will take some serious work to make it what I want it to be when it goes on the bigger motor. That motor will be built to run higher revs safely with a stronger more stable bottom end. I'll have the G2s freshened up and revisit my port work with what I have learned in 17 years. Then armed with all the information, I'll figure out just what to do with the XT to make the most of these heads and a cam to go with them.
     
  17. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

  18. ASE Doc

    ASE Doc Member

    I'll post photos as soon as I get going. Hopefully in a few weeks.
     
  19. ASE Doc

    ASE Doc Member

    Sorry, no photos yet. No progress yet. I've been reading through the links Grumpy posted for me, studying up to prepare for this intake swap. One thing I came across was an article detailing an HSR install on an IROC. I was surprised to read that they had hood clearance issues. The interference occurred at the front of the throttle body. This gives me pause considering that the TB on the XT stands at least as tall as that of the HSR. A big part of the problem is the bulky 90mm TB Eddy designed the XT around and the fact that it protrudes above the top of the plenum. I'm seriously considering modifications to the XT to fit the 58mm dual TB that I already have on my TPI. Using this TB would save me a bit of additional work swapping cables and adapting TPS and IAC harnesses. More importantly, it would allow me to modify the TB mounting of the XT to provide ample hood clearance in the IROC.

    One article that I've looked through a few times, covered installation of the XT on a C4 vette. They had only minimal clearance issues and were able to mildly modify the front corner of the manifold to achieve clearance. Having worked on a few C4s and being familiar with their slim hood profile, I was encouraged that the XT fits this car. Now, I'm having second thoughts. I'll get hold of some Playdo(maybe borrow some from the grandkids) and use it to do some measuring of hood clearance on my 87 IROC. If it looks like clearance may be an issue, I'll go to work figuring out how to adapt the 58mm TB. I see that there is one adapter available but I don't know how it might affect airflow into the plenum. I have no problem modifying the XT to make the 58mm TB work its best. I wish I had Grumpy's welding and milling capabilities. I would really go to town on this thing.

    I'll keep you guys posted.
     
  20. ASE Doc

    ASE Doc Member

    Here's a link to a thread on a Corvette forum where a member made his own adapter to install his dual blade TB on the XT. I had seen this thread before and passed it by, thinking I would use the 90mm TB from Eddy. Last night as I thought this over, I pretty much decided that I will adapt my 58mm TB to the XT. In fact, if done correctly, it may work better with the XT's plenum to provide balanced cylinder filling than the 90mm.

    https://www.corvetteforum.com/forum...e-with-diy-adaptor-for-tpi-throttle-body.html


    Here is another way to install the Pro Flo XT on a 350 C4 Vette. I made an adaptor so I could use my TPI TB and cables. I also reused my Holley SP fuel rails and regulator. You need a small HEI distributor and remote coil. I used a TPIS Mini ram water neck. With this setup, hood clearance is no problem, about a ½ inch at the TB. (See the photo with the yellow clay on top of the TB). I made the adapter with a 2in hole saw and a drill press. I cut off the upper tab for the LS TB with a circular saw and a plywood jig bolted to the manifold to cut straight. I drilled and tapped the side of the intake to mount a Holley throttle cable bracket to the driver’s side of the intake. I made a plastic wedge to get it to line up with the TB. I haven’t had it dynoed but my SOTPs meter feels good.


    [​IMG]


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    Last edited by a moderator: Dec 7, 2017

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