Porting the Edelbrock Pro Flow XT 7137

[Maniacmechanic1]

I would not be overly concerned with Plenum volume since your building a high performance street car.

To get an engine to Rev to 7000 + takes lots of Camshaft duration.
We Enter the Danger Zone Grumpy does not like.
And he is right in many cases because most do not purchase and use the correct components to go there.
Titanium Intake & Titanium Exhaust Valves, Titanium Retainers, & Titanium Valve Locks.
$3,000 cash right there.
And the Camshaft chose needs less aggressive softer lobes or ramp speeds.
Premium Valvesprings too.
And You need the best connecting rods available. Titanium or Forged Steel Made in the USA.
Titanium Rods will cost $5,000-$7,000.

I am talking about an Endurance style engine built for Drag Racing so it will last.
The parts and prices blows away most people's budgets.
So they skimp with bad results, blown up.

 

[Indycars]

I don't know what he has. He mentioned mapping the plenum walls and floor, also mapping the original plenum top cutoff and transferring the data into his CAD software for use in design of the new plenum.

When I did 3D forensic animations I had to have very accurate models, usually a vehicle. I
purchased them from a company that could digitize a full size car. Your situation is on a much
smaller scale and the cost would be more affordable. Back then it was a physical 3D digitizer,
now I think they use lasers.

I was interested in the process they have now for creating 3D models.

I base my thinking on plenum size around 1/2 - 2/3 engine displacement for an engine producing peak power between 6,000 and 6,800 rpm.

Thanks I was wondering how you were coming up with your numbers. The math seems easy enough.

 

[Grumpy]

I would not be all that concerned with plenum volume, simply because each individual cylinder draws from the plenum only,
every other crank shaft rotation, the intake valve opens, and runner flow,
spaced at 90 degrees,as long as the plenum is at least about 1/2 the engines cylinder volume,
as the throttle body is constantly allowing far more air flow into the plenum than any two or three cylinders can draw from it.
remember the cam controlling the valves rotates at 1/2 the crank speed so it only makes a single 360 degree rotation for every two full crank rotations.
keep in mind that while the rate of flow increases as the rpms increase theres no point in the engines power band,
where even if four cylinders were drawing simultaneously come close to matching the throttle body flow rates.
connecting a vacuum gauge on the plenum should easily prove theres no significant vacuum reading at w.o.t.
a high vacuum in the plenum indicates a significant restriction to air flow,
most tunnel ram and common plenum EFI or even single plane ,
carburetor intakes with much smaller plenum volumes,
have only marginal vacuum readings at wide open throttle

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[ASE Doc]

Thanks Indy and Grumpy. On a 406, should I get to build the Dart block based motor that I've planned with Somer's Machine, the resulting plenum will be 1/2 engine cid. On a 383 it's not far from 1/2. On my current 355, it will be closer to 2/3, which is still in range. I think you'll agree that more important than plenum volume is plenum shape and how it aligns with the throttle inlet and runner entries. I think we've got that pretty well covered on this project. The XT's plenum floor and runner entries were well conceived. We are revising the upper portion of the plenum to work with the dual throttles. In fact, it will end up looking alot more like your HSR plenum.

Still no news from the machinist. I'll reach out to him if I don't hear anything soon. He promised photo updates, that jerk . He's a great guy and I know he's working hard, so I'll be patient. It helps that the car is drivable as is, so at least I can enjoy it while I work to get the XT finished. About two more months and the weather here will be suitable for bringing the car out of winter storage. I still need to finish my exhaust system too. I started summer before last building a new dual 2.5" exhaust. Issues with the fuel system and transmission had me back tracking last year to get these areas up to snuff. I still have my temporary dual glass pack under car dump attached, which makes the car much less enjoyable to drive. This summer, I will task myself with finishing the exhaust install. That's in addition to the XT.

 

[ASE Doc]

Heard from Travis today. He's having to rethink the fixture he'd planned for mounting the XT on his mill. The intake is longer than his mill's table. He has solution in mind and will get that going. We're in agreement on the plenum solution, while there are still details to work out. More updates to come soon.

 

[ASE Doc]

Here are some photos from Travis of his progress on the XT. Should be back to me soon for completion of the porting work.

 

[ASE Doc]

If you visit an engine machine shop around this time of year, someone like my own machinist, Somers Automotive Machine in Vancouver WA, you'll see rows of local Nascar motors, mostly SBC, with dyno tags that read things like 720hp @ 7,200rpm. These motors are built with chome moly crankshafts and rods at an average cost of $15,000. It depends somewhat on which motor your building and how much rotating mass you're dealing with. A small block chevy naturally has a small rotating mass. It doesn't take too much to make an SBC rev safely to 6,500 or even 7,000. Precision balancing of the rotating assembly along with sufficient oil pressure and volume are most important. Naturally, the more time an engine spends at high revs, the less durable it will be.

 

[ASE Doc]

Thanks Grumpy for your reply concerning plenum volume. It's not inlet restriction that I'm concerned with but rather motion control of the air within the plenum. A smaller plenum, is more likely to suffer from turbulence at higher inlet velocity. A smaller plenum of course also benefits more from pressure wave tuning. It's a balance between the two that I'll be trying for. Since the intake will start out on a 355 and eventually end up on either a 383 or 406, the factors determining ideal plenum size will change. This is one benefit to a removable top, plenum size can be changed later on if we so desire.

 

[Grumpy]

its jobs like that welding on the aluminum intake,
custom mods, milling machine work on the sealing rails,
being done too that intake manifold too allow the upper plenum,
to have a well matched sealing area that in the past cost me thousands of dollars at machine shops
after awhile if your even marginally mechanically inclined you have to start thinking about,
the value in owning a mill, and if you have some place to put it and use it.
let me state that the mill itself is not the only cost, the tooling , vises, cutters, clamps
chucks, mill bits, precision measuring tools,coolant pumps
required to get it up and useful adds considerably to the costs
and yes you'll need a decent welder and yes there's a steep learning curve.
don,t get frustrated there's not a single thing or skill,
the average guy can,t learn to do well,
with practice if you purchase decent equipment.
yes it seems like an endless and bottomless money pit,
but you will see constant and steady improvements over time,
as you gain skills and better tooling and experience.
jubs that were far beyond your skill level to even attempt at first,
will over time become common place and looked on as no big deal.
obviously if your not a confirmed tool addict / junky ,this might not sound like a good use of your financial resources, but it will allow you to get ever increasing tools, more skills and ever deeper into hod rodding at a much higher skill level than most ever achieve.
keep in mind if you have a mill, lathe and a decent welder and the skill and experience too use those tools, theres very little that you can,t either fabricate, effectively modify, build or customize
how many guys have larger machine tools like a MILL ,lathe ETC. ?

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Have one to sell? Sell now
Weiand 6221 Offset Thermostat Housing Adapter For Small Block and Big Block Chev
your problem is VERY COMMON, if the throttle body and thermostat housing has a clearance issue on some modified EFI intakes, heres the usual cure

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[ASE Doc]

Thanks Grumpy, I couldn't agree more. As a 40 year automotive technician, I have about 140k invested in quality tools and equipment. For the past 28 years I've focused on diagnostics of EFI and vehicle electronics, a field which expands each year. Over the past several years, a lot of my tool budget has gone to staying up to date with my diagnostic equipment. I use my Snap On Modus Ultra almost constantly every working day. Either the scan tool for communication with a module or the lab scope for testing signals.

I have collected some fabrication equipment, including a nice little MIG welder from Eastwood. Ive already used the welder to build my own fuel tank sump design. Its not perfect but it works well. Im planning to finish my own dual exhaust design this summer. When it's finished, ill post photos in a new thread.

I don't know if I'll get a mill of my own though at least a drill press would be nice.
At this point, I am very fortunate to be surrounded by a group of very gifted young people. Namely my children and their friends. My machinist is one of my two engineer sons' brother in law. He is excited to be participating in the XT project and will not accept payment for his time. This is a rare privilege that most guys don't enjoy. I am truly blessed with my brilliant gifted children. Not only do I enjoy the services of Travis's complete machine shop but I also really enjoy visiting and working with him. I look forward to finding more projects for us to collaberate on.

 

[ASE Doc]

Btw I did some research. I love your Fox mill. I'd like to help Travis get one like that. You can't really see in the photos, he has a decent old vertical mill. It works fine but it has its limitations. He would love a mill like the Fox.

 

[Loves302Chevy]

I hope you are paying Travis in cases of beer, at least.

 

[Grumpy]

when I was in college I had several classes in how too use larger machine tools like lathes and mills,edm machines etc.
(this was well before computer controls)
I thought I had the basics down rather well, as I was rather skilled if you were to judge by the grading parameters, at the time.
we were only given a dozen or so simple tasks like to machine a steel block to a precise 2" x 3"x 4" size ,
drill a precise size hole and cut a steel rod that would slide through that hole with less than .0003-.0002 clearance,
but it gave you a feel for the machine function
once I decided I wanted a mill I looked for a deal on a used mill,
and could not find one in decent shape at a reasonable cost, I eventually found the FOX mill on sale
(about $5k delivered to a local dock, then I paid about $300 to have a guy move it to my shop)
then the realization hit that the collets, tooling, cutters vise, coolant pump were all needed in addition to the basic mill.
and yes Id forgotten some of the basics so I needed to read and watch videos, but over time the mill has saved me far more than it costs.

 

[ASE Doc]

Grumpy, It looks like a beautiful machine. I'm trying to remember what brand of mill Travis has. Its an older used machine, but it works fine. Hes added a digital readout and is working on adding a power feed as well.

Just for curiosity sake, I did some price shopping for a 5 axis CNC mill online. Lol. Pretty clear why we don't all have one. A 5 axis mill that would take a part the size of an intake manifold, $145k. Heck buy two, they're cheap.

Loves 302, I'm thinking of a gift certificate to his wife Amy's favorite restaurant. A half rack of Travis' favorite beer as well.

 

[ASE Doc]

Nothing new to report. I assume Travis is making progress as steadily as time allows. I'm constantly reading and looking for any new information that may challenge my own ideas. I came across a good article the other day in Super Chevy detailing installation of a Holley Stealth Ram on a massaged 350 in an 86 IROC. It was interesting to me for one because it deals with installation of the tunnel ram intake in my car's underhood. They ran into the same clearance issues most do with the HSR in a 3rd gen F-body. The same issues I would have had installing the XT as shipped from Edelbrock. I'm still not finished verifying clearances and making the final decision on plenum height for this redesign. I'll get there soon. Also interesting were the performance numbers for the car before and after the install. Before, the car's numbers pretty much mirrored my own car's performance in the 1/4 mile. 12.9-13.0 seconds ET is right about where I was heading with my TPI. I have a larger cam and probably better flowing heads, though both of these things are choked way down by the TPI. I also have larger runner csa in the Superram base than they probably achieved in their ported stock base. Again, larger flow capacity in any part of the TPI is of limited value given the 22" runner length. While I was able to shift the under the curve torque maybe 500rpm from what they may have had, the motor still drops hard above 5K.

The car in the article has runners that, while they may not have the CSA of my large tubes, are length optimized. It has twisted wegde G1 heads and smaller cam are in fact a better match for the TPI. It also has ET drag radials while mine wore the same BF Goodrich TA Comp 2s it always wears when I ran it down the strip. In any case, the two motors, mine and the one in the article started out pretty even. After the HSR install, and a dyno tune that was limited to adjusting base timing and fuel pressure since they were using a factory ECM and PROM, the article car ran 12.3 second ET. They determined also that after installing a new PROM, written to better compliment the engine, performance improved even more and would likely result in lower ET yet.
This gives me some indication of what to expect from my XT install, since the HSR and my ported XT should produce fairly similar results. Also interesting was their dyno results, which indicated about 420 flywheel HP(330 at the tires). More interesting yet was that they did this with 24lb injectors. In fact, after viewing O2 sensor data, the dyno tuner reduced fuel pressure to 38psi and got more power from the motor.

I may get a touch more out of my larger cam and heads, but maybe not alot more. I chose 35lb/hr units with plans to run minimum pressure of 43.5psi to support 450hp. If my motor ends up closer to 420hp, the 35s will be too much injector. I have always leaned toward smaller nozzles, higher pressure for better atomization. Having to drop pressure below 40psi trying to make too large injectors not overfuel the motor would be counter productive. I also verified with Edelbrock tech that the PICO injectors are stable up to 90psi. Which means that they are safe up to at least 70psi. This allows quite a bit of upward flow rate adjustment by increasing pressure. More pressure also makes smaller droplets which is a good thing. This new informatio has led me to decide to send back the 35lb injectors in exchange for 29lb. The 29 lb units will allow plenty of adjustment up to about 470hp which I'm sure I won't acheive with this 355 build. Later on, when I do build a larger motor, I'll go with larger nozzles to fit that build, rather than trying to play around using one size nozzle to fit two very different engines.

 

[Maniacmechanic1]

The 3Rd Gen F body cars make decent budget drag cars able to be street driven yet.
The 10 bolt 7-1/2 when it dies kills the Fun.
If you get into the rear diff to change gears set the backlash to .005".
Richmond Gear allows you to go that that tight and get a decent pattern if the pinion depth is Dead On The Money.
Run 85-140w gear oil. I use only Royal Purple Gear Oil.
I have built a few of those 3rd gen10 bolts and guys ran 11s in the 1/4.
If they last 1 year its a Total Success.

Build it.
Tune it.
If you have a 700 R4 it will work nice with 3.73 rear diff gears.

I built a few with 4.56 gears those GM 7.5s.
Engine needs to RPM.
327 Small Blocks back in the late 1990s.

If the 700R4 does Die go Turbo 400.
Its a Close Ratio Automatic the gear spread.
Torque converter selection is better than any other trans out there.
They will take 800 Hp near stock.
Everything is Heavy Duty internal in a TH400.

 

[Grumpy]

either injector size should work in the currently listed combo, with proper tuning but I think the 29lb will be close to max capacity if you get it tuned correctly.

 

[ASE Doc]

Thanks guys. This isn't a drag car. I only take it to the strip for performance testing. The 3rd gens real strength is exceptional cornering and aerodynamics. The chassis is built to optimize cornering and stability. I built the 700r4 myself to be about as strong as possible. If it fails, I'll build it again even stronger.

I keep thinking too of how much I would like to have a 6 speed, like the super T56. I built the 700r4 to take manual shifting without complaining. Maybe once the motors done, I'll look for a 6 speed.

I hear you Grumpy on injector size. I won't argue with your knowledge or experience. In my own experience, I have had more issues trying to tune an engine with too much fuel than with too little fuel. I wish I could get these compact PICOs in 32lb, I could spit the difference.

Once it's together, we'll know soon enough if the 29s were the right choice. If not, I'll go back to the 35s.

On the wimpy rear axle. I went through it when I first bought the car. It's tight but still weak for sure. It should survive as long as it never sees any serious traction. Its filled with Valvoline 75w140 synthetic.

 

[Strictly Attitude]

3 replies in a row. I feel like I'm hogging the mike here. I wanted to say, the injectors I'm planning to use are 35lb/hr, rated of course at 3 bar, or 43.5psi. Using an injector size calculator, this size injector fits 450hp. I was planning on 33 lb Bosch IIIs and increasing pressure as needed to serve the 355 now and the larger engine later. I have a very strong fuel supply system with a Fuelabs variable speed pump capable of much more than this engine needs.

I like to run smaller nozzles at higher pressure to improve atomization. However, I'm also trying to be practical and buy just one set of nozzles that will work in the 355 and can then be adapted to the 383 or 406 in a few years. I'm thinking the 35lb units will do this for me. As long as I don't get the injector pulse to short on the small motor trying to tune idle fuel, it should work.

You can tune injectors with fuel pressure along with pulse width. Some injectors don't like being pushed too hard but seems you bought all good stuff.

Permatex High Tack. I have a warning on the use of this product. It does a great job of sticking a gasket to a surface. Unfortunately, it doesn't do so well at preventing a gasket slipping or shifting. In fact, since it doesn't harden for some time after application, it can even lead to a gasket being sucked in or pushed out. I've had issues using it on oil pan gaskets. It's okay, just be sure to only apply it to one side of the gasket and leave the other side dry. High Tack on one side and RTV on the other is a pan gasket that is sure to squeeze out of place after tightening. It will really ruin your day when it happens after the motor's back in the vehicle. One product that will actually retain a gasket against slipping is Edelbrock Gasgasinch. My machinist turned me on to it for retaining oil pan hoop seals. K&W Copper Coat gasket sealant is another product that I've had success with on intake gaskets.

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EDIT: corrected name of K&W Copper Coat and added a link to the product

Little trick the spray stuff you need to put on then let it get tacky before applying first. Also same goes for spray adhesive on vinyl tops and interior parts such a coving things with leather.

Thanks guys. This isn't a drag car. I only take it to the strip for performance testing. The 3rd gens real strength is exceptional cornering and aerodynamics. The chassis is built to optimize cornering and stability. I built the 700r4 myself to be about as strong as possible. If it fails, I'll build it again even stronger.

I keep thinking too of how much I would like to have a 6 speed, like the super T56. I built the 700r4 to take manual shifting without complaining. Maybe once the motors done, I'll look for a 6 speed.

I hear you Grumpy on injector size. I won't argue with your knowledge or experience. In my own experience, I have had more issues trying to tune an engine with too much fuel than with too little fuel. I wish I could get these compact PICOs in 32lb, I could spit the difference.

Once it's together, we'll know soon enough if the 29s were the right choice. If not, I'll go back to the 35s.

On the wimpy rear axle. I went through it when I first bought the car. It's tight but still weak for sure. It should survive as long as it never sees any serious traction. Its filled with Valvoline 75w140 synthetic.

I also have 700r4 well built manual valve body engine braking I like the TKO 600 $1000 less then 6 speed if you plan on road course track days chances are you will never use all 6 seeing allot of real race cars love the ole 4 speed. I want the 5 for the OD to keep it street able. My version of street able does not match many though maybe Brian lol

 

[ASE Doc]

Thanks Strictly Attitude. I'm pretty familiar with Permatex High Tack. In fact I have a can sitting on my own chemicals shelf. Unfortunately, you will find that even after setting up, it still doesn't prevent gasket shift. It will eventually harden but not for a long time. The shifting isn't always an issue. If you use The spray to stick a valve cover gasket to the cover and leave the other side dry, it's fine. The gasket will squeeze out only if there is any kind of sealer between the gasket and cyl head, which there should never be anyway.

The first time I saw the shifting problem was on an oil pan where I used high tack to hold the cork to the block and then a thin film of rtv to seal the gasket to the pan. The high tack was allowed to fully tack up before the gasket was put in place. The next day, the gasket had pushed out between the bolts all the way around and had to be redone. Water pumps the same thing. The gasket will push out and split around the small passage below the bolt on the RH side. Ive tried it many different ways. Your fine as long as you leave one side of the gasket dry.

My 700r4 has been a learning experience. I originally had it built many years ago. It held up for quite a while before high rev manual 2-3 shifts finally took out the 3-4 clutches. I tore it down and was disappointed to find not much had been done to strengthen it in the first place. It had a few key parts upgraded from stock but for what I paid it wasnt much.

I built it myself using some really good stuff. I like the Sonnax parts. The Smart Tech Input Housing for one. It really beefs up the 3-4 clutch. I run an 8 stack of BW high energy in this clutch. The Smart Tech prevents any coning. I also replaced all thrust washers with needle bearings and the new pump and valve body I built to run 280psi line pressure by 2,500 rpm. Its a tough little unit now and after studying up on it and building it a few times, I know it pretty well and can go through it over a weekend.