Porting intake - Page 9
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Thread: Porting intake

  1. #161
    Senior Contributor asdasc's Avatar
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    I have a question that maybe only RallyBob can answer, but if others of you know, please help me out. I am grinding away at an intake manifold. All I have access to is the 1970 version that has the restricted plenum. According to Bob's article, the best one to port is from a 1973 or later 1.9 intake.

    My plan was to use this as practice while I looked for an ideal doner.

    This is so much work, I don't want to do it again!

    So the question is, how much of a difference is there between a ported version of each - early versus later model of the intake? Is the difference significant between them, or is it just a 'little' better?

    I am just using it for street use, and don't have a 'full race' motor, but it will have 2.0L pistons, etc. My whole goal is to improve 0-70MPH performance. I won't probabaly ever have the chance to run it for extended periods at high RPM, other than cruising on the highway.

    Thanks,
    Steve
    "ever notice you are never done tinkering with the GT?"
    Never mind, I am WAAAY beyond tinkering now...

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  3. #162
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    Jeff try 1-800-447-2886 and get spooked, says he has 10 of them.



    Last edited by kwilford; 02-27-2006 at 11:53 PM.

  4. #163
    Opeler turbocon86's Avatar
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    I just got done reading all the posts in this thread. The 'tent" seems to be a good idea, however it is accomplished. The "turtle" post got my gears working. I'm thinking of making this out of billet aluminum and using the "bolt through the bottom" method of mounting it. Thoughts?

    Ric D.
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    http://www.ricdidonato.com/Downtime/index.html

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  6. #164
    Code Goober
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    Is the effort worth the gain over the simple tent?
    No, that's not a defect, that's a feature.

  7. #165
    Senior Contributor asdasc's Avatar
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    TurboCon,

    Yes, my imagination tells me that if it is blended into the existing manifold properly that this would be the best design. Please let us know how it turns out.

    From what I understand, this tent makes a big difference in the torque when done properly.
    Steve
    "ever notice you are never done tinkering with the GT?"
    Never mind, I am WAAAY beyond tinkering now...

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    After reading this post I decided to give it a go here. I machined out a Tent from solid aluminum and radiused it to match my manifold, one of the old types. I used to 1/4 inch screws to secure it permanently and then used lab metal to fill in the gaps. I've used lab metal in the past as a filler for aluminum gas tanks to be powercoated. It's rated to 1000 degrees. After the filler hardened I used 40 grit rolls to blend and rough everything. This should help until I can get my FI project started. In the last picture you can see a hole drilled in the treads of the brake vacuum outlet. That hole reconnects with the lower vacuum line which was blocked by the tent.
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    Last edited by Washout; 01-21-2007 at 11:45 PM.
    I call her Laticia, Costs more than she's worth, but what a set of headlights!

  9. #167
    Tennessean Site Supporter hrcollinsjr's Avatar
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    Ultimate Torker Manifold?

    Iíve been trying to figure out the best way to modify a manifold after thoroughly reading and looking at all of the pictures I could find. I donít own a machine shop and donít weld Al so Iím at otherís mercy. Costs which might become prohibitive are somewhat of a concern. I donít want $200 to $300 in a manifold that will net me 10 or 12 hp, maybe. With that being said, Iíve contacted a local machine shop about how to proceed. It was suggested that the bottom be milled off and a window cut open so the welder could weld the raised (tent) floor in. The initial machine work was estimated at near $100 but that was to make a jig to hold the manifold for milling and to write the program to cut the window in the floor. I still have to carry the manifold to the welder and donít have an estimate from him. My job is to communicate what I want, do the leg work and porting.

    My engine will be a 2.0L and I will use a mild hyd. cam grind from Cam Techniques (probably 212 @ .050 - .246í lift). I havenít settled on the valves yet. The engine I did last year for a friend is identical up to this point, we used 2.0L Opel intake valves with 1.9L exhaust valves.

    Now that the background is kind of out of the way. Iím planning on using a Weber 38 DGES. Since I donít race I would prefer a good tractable engine that pulls strongly all the way to say 7 grand. Iím toying with installing a divider to separate the two barrels of the carburetor in the intake. If I do this it will effect the characteristics of the engine drastically I would think. Do the divider or not? Height of the divider? Will there be a need to jet the carb differently for each barrel? Can someone come up with a good idea on how to make an adjustable divider so I can try different heights without making a new manifold each time.

    The engine I put together last year may very well be the test mule for this set up. Hope the owner doesnít notice this thread since I havenít mentioned it to him yet. ;-)

    TIA,

    Harold

  10. #168
    Cunning Linguist Site Supporter tekenaar's Avatar
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    LightbulbSome answers maybe . . .

    Quote Originally Posted by hrcollinsjr View Post
    I’ve been trying to figure out the best way to modify a manifold . . . 1. I don’t want $200 to $300 in a manifold that will net me 10 or 12 hp, maybe. With that being said, . . . that the bottom be milled off and a window cut open so the welder could weld the raised (tent) floor in. The initial machine work was estimated at near $100 but that was to make a jig to hold the manifold for milling and 2. to write the program to cut the window in the floor. . . .

    My engine will be a 2.0L and I will use a mild hyd. cam grind from Cam Techniques (probably 212 @ .050 - .246’ lift). . . . we used 2.0L Opel intake valves with 1.9L exhaust valves.

    . . . I’m planning on using a Weber 38 DGES. . . . I’m toying with installing a divider to separate the two barrels of the carburetor in the intake. If I do this it will effect the characteristics of the engine drastically I would think. 3. Do the divider or not? Height of the divider? Will there be a need to jet the carb differently for each barrel? Can someone come up with a good idea on how to make an adjustable divider so I can try different heights without making a new manifold each time.

    The engine I put together last year may very well be the test mule. . . ;-)

    TIA,

    Harold
    1. Everything's relative, Harold, $200-300 for 10-12HP doesn't sound so good taken by itself. It's a different story entirely when looked at relative to your particular engine, however. 10-12HP gain for a ~120HP engine is a "horse" (pun intended) of a different color entirely, 9-10% HP gain.

    2. I'd check at a machine shop with a manual vertical mill, using a CNC machine for a "one-off" seems overkill and probably affects the end pricing too. My local guy would do the machining AND weld it . . . just a thought.

    3. I'd say "NO", the cylinder pairing (1/4, 2/3) which would result from this divider is "unbalanced" . . . all wrong. Based on the firing order (1-3-4-2), you'd end up with the left barrel feeding its cylinder pair (1/4) during one revolution and the right barrel feeding its cylinder pair (2/3) during the next . . . . . . CRAP!! . . . senior moment . . . thinking about SSD manifold! This manifold would feed from the two carb throats alternately (180° apart), thus "balanced" . . . turning over to RBob . . .
    Last edited by tekenaar; 06-13-2007 at 11:58 AM. Reason: fuzzy logic, thinking SSD


    1960: '61 Rekord PII 1.7 3S 3.9 '69 Kadett LS 'sprint' 1.9 3A 3.18
    1970: '70 GT 1.9 4S 3.44 '72 GT 2.2SSD 5S 3.44 '72 GT 2.4FI 5S 3.44P
    1970: '73 GT 1.9FI 4S 3.44 '75 1900 1.9FI 4S 3.44
    1980: '85 Bitter SC 3.9FI 5S 3.44P
    2000: '09 Solstice GXP Coupe 2.0 SIDI VVT "Stage 2" Turbo 5S 3.73P


    "De inimico non tantum loquaris male, sed cogites."

  11. #169
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    Quote Originally Posted by hrcollinsjr View Post
    I haven’t settled on the valves yet.
    Harold, I just finished a head for my daughter's 71 GT. I bought Manley RaceFlow valves... using the same part numbers Bob has listed in the past. The cost of the valves, from a Manley distributor, was $140.90, shipping included. These valves are the perfect addition to any Opel head when ported to Bob's street porting article.
    Last edited by Paul; 06-13-2007 at 12:39 PM.
    Paul

  12. #170
    Project 1450 supporter... Site Supporter RallyBob's Avatar
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    Quote Originally Posted by hrcollinsjr View Post
    I don’t want $200 to $300 in a manifold that will net me 10 or 12 hp, maybe.
    Believe it or not, it's still probably the best thing going for HP/dollar ratio. If you had an honest 100 hp you could get as much as 10-12 hp from the intake mods. But going from a Solex to a 38 DGAS will only net you 7-8 hp, and the 38 DGAS costs more than the intake (especially if you port it yourself).
    A header and exhaust cost a lot more, and you'd be lucky to see 10 HP from this combined upgrade. Ignition? Maybe 2-3 hp on most engines (but better response and driveability).

    Easiest way to open up the bottom of the intake is with a hole-saw. Like this.

    More recently, I use a vertical bandsaw (woodworking blade) and cut the lower plenum off flush with the intake bottom, then notch it in a 'V' shape with the bandsaw to emulate the peaked floor I will later weld in. I generally notch vertically to halfway between the brake booster fitting hole and the EGR fitting hole. Then you make the sheetmetal 'peak', and weld it in from underneath. Much easier and faster this way.

    Here's the previous info I posted on custom valves from Manley.

    HTH,
    Bob
    Last edited by RallyBob; 06-13-2007 at 12:50 PM. Reason: edited to appease the gods of spelling....hey, 'f' and 'g' are right next to each other on the keyboard, give me a break...

  13. #171
    Tennessean Site Supporter hrcollinsjr's Avatar
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    Otto,

    To address some of your points.

    1. $ I understand what you are saying and don't totally disagree. It isn't always about horsepower either. A big concern to me is improved throttle respond and what the heck maybe it'll help the MPG slightly or at least not have a negative effect.

    2. I didn't say I was going to stop at one. I'm not talking about mass production but I can see me making 5 or 6 if they turn out well.

    3. Incorrect cylinder pairing? That's extra work and money to find out something that I could have been told up front by someone who knows that I'm wrong. That's why I'm asking.

    Harold

  14. #172
    Project 1450 supporter... Site Supporter RallyBob's Avatar
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    Quote Originally Posted by hrcollinsjr View Post
    Iím toying with installing a divider to separate the two barrels of the carburetor in the intake. If I do this it will effect the characteristics of the engine drastically I would think. Do the divider or not? Height of the divider?
    If I am reading correctly, you are looking at pairing cylinders #1 and #4 together, being fed only by the outward throttle plate, and #2 and #3 will be paired, feeding off the inward throttle plate.

    I would tend not to do this, as you are defeating a lot of the advantages of a plenum style intake. For example you are only drawing air/fuel from one barrel per cylinder. Normally you can store a 'charge' of air/fuel in the plenum, fed by both barrels, and when the next cylinder-in-line opens the intake valve, that 'charge' from both barrels is ready to feed that one cylinder. With a divider, you will only get the 'charge' volume of one throttle plate. It would probably have better low end torque, but I suspect that from 4500 rpms>up it would be severely flow impaired. Unless you used a much larger carburetor. With the full-height divider the engine 'thinks' you have a much smaller carb on there than you actually do. This is essentially the theory of a single sidedraft carburetor as well.

    That said, I have experimented with partial dividers, in conjunction with the 'tented' plenum floor. I basically extended the existing central runner dividers to the middle of the plenum, and at a height of approximately 1/2 the overall plenum height. It seemed to help the response without seriously affecting top end power. But, I also spent about 10 hours fitting and shaping the dividers to get them to distribute the fuel evenly. That was a lot of work on the flowbench and the grinding bench for little gain!

    Bob

  15. #173
    Cunning Linguist Site Supporter tekenaar's Avatar
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    Quote Originally Posted by hrcollinsjr View Post
    Otto,

    To address some of your points.

    1. $ I understand what you are saying and don't totally disagree. It isn't always about horsepower either. A big concern to me is improved throttle respond and what the heck maybe it'll help the MPG slightly or at least not have a negative effect.

    2. I didn't say I was going to stop at one. I'm not talking about mass production but I can see me making 5 or 6 if they turn out well.

    3. Incorrect cylinder pairing? That's extra work and money to find out something that I could have been told up front by someone who knows that I'm wrong. That's why I'm asking.

    Harold
    2. Yeah, for "more than one", CNC would be more cost effective because "set-up" and programming cost would be spread over the "run" rather than just one unit.

    3. Mea culpa! . . . "fuzzy logic/senior moment" at work there . . . turned over to RBob!


    1960: '61 Rekord PII 1.7 3S 3.9 '69 Kadett LS 'sprint' 1.9 3A 3.18
    1970: '70 GT 1.9 4S 3.44 '72 GT 2.2SSD 5S 3.44 '72 GT 2.4FI 5S 3.44P
    1970: '73 GT 1.9FI 4S 3.44 '75 1900 1.9FI 4S 3.44
    1980: '85 Bitter SC 3.9FI 5S 3.44P
    2000: '09 Solstice GXP Coupe 2.0 SIDI VVT "Stage 2" Turbo 5S 3.73P


    "De inimico non tantum loquaris male, sed cogites."

  16. #174
    Tennessean Site Supporter hrcollinsjr's Avatar
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    Bob,

    I have one of your manifolds "borrowed" to look at. That's part of the reason for the push to get it done before the owner reclaims it.

    I don't fool with the Solexes, every time I do I remember why I swear I'll never do it again. I've always run 32/36's.

    Best bang for the buck? No Doubt! It amazes me the horsepower gains from the intake mods alone.

    Thanks,
    Harold
    RallyBob likes this.

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    Quote Originally Posted by RallyBob View Post
    Then you make the sheetmetal 'peak', and weld it in from underneath. Much easier and faster this way.HTH, Bob
    On a more serious note... By this, I presume you form up a sheet of Aluminum into the peak shape and height you desire... What works better a sharp or rounded peak? What thickness is the material you weld back in? And, how carefully do you blend in the peak's material with that of the floor and adjoining walls...

    Thanks....
    Paul

  18. #176
    Project 1450 supporter... Site Supporter RallyBob's Avatar
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    Quote Originally Posted by Paul View Post
    On a more serious note... By this, I presume you form up a sheet of Aluminum into the peak shape and height you desire... What works better a sharp or rounded peak? What thickness is the material you weld back in? And, how carefully do you blend in the peak's material with that of the floor and adjoining walls...

    Thanks....
    Well, just like everything else in life, there's no set answer. I'm constantly evolving my intakes, so they are ever changing. Most recently, I make the 'tent' from two separate pieces of aluminum, and weld them at the peak. This leaves a blunted top edge, rather than a sharp edge. I make them from .080" material these days, although I've tried both .063" and .125" thick.

    The .063" is a bit tougher to weld to the thicker intake material, while the .125" is easier to weld but tougher to cut and shape to fit. The .080" is a nice compromise.

    I weld the material from the underside, so there is no blending inside the plenum at all really. When I used to pay to have someone weld the 'tents' in place, it was from the inside. But this was time consuming and very costly, although it made the inside look nicer. Performance wise? I have seen no difference.

    My next intake project (for me, not for sale!) is a fully fabricated intake from scratch, with hammer-formed runners that are .063" thick, and with a fully hand-shaped plenum. I suspect it will weigh about 1/2 what a stock intake weighs, and I can finally remove the OEM tight curves of the stock intake, as well as enlarge the runners consistently. It will have to sit a bit higher than stock too, so it won't fit under a GT hood. I'm guessing about 12 hours of labor to actually fabricate it, but I've already started making my hardwood hammerforms for it.

    Bob
    Last edited by tekenaar; 06-14-2007 at 06:55 PM.

  19. #177
    Detroit,where my home was 2 Fast 4 U's Avatar
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    Quote Originally Posted by RallyBob View Post
    My next intake project (for me, not for sale!) is a fully fabricated intake from scratch, with hammer-formed runners that are .063" thick, and with a fully hand-shaped plenum. I suspect it will weigh about 1/2 what a stock intake weighs, and I can finally remove the OEM tight curves of the stock intake, as well as enlarge the runners consistantly. It will have to sit a bit higher than stock too, so it won't fit under a GT hood. I'm guessing about 12 hours of labor to actually fabricate it, but I've already started making my hardwood hammerforms for it.

    Bob
    Are we going to see any photo's as you make the intake??
    Opel Ascona;
    Only built from 1970 - 1975




    Understeer: The front of the car hits the wall,
    Oversteer: The rear of the car hits the wall,
    Horsepower: How fast the car hits the wall,
    Torque: How far the car pushes the wall.

  20. #178
    Project 1450 supporter... Site Supporter RallyBob's Avatar
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    Quote Originally Posted by 2 Fast 4 U View Post
    Are we going to see any photo's as you make the intake??
    Nope. I still don't have a new digital camera. And very soon, once my family sells their business, I won't access to a computer anymore either, not until I can afford to buy a new one. So you won't hear from me for a few months at least I think.

    Bob

  21. #179
    Project 1450 supporter... Site Supporter RallyBob's Avatar
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    This is again a bit off-tangent, but it shows my priorities regardless.:banghead:

    No, I won't buy myself a new computer unless I have the cash for it. But, I did just order a new Garrett ball bearing GT2554 turbocharger on my credit card. I am going to build that Opel turbo 'kit' after all, and will prototype on my own car. Basically I will just build a manifold that fits the Manta/Ascona chassis, and will create an instruction sheet to build the rest of the system yourself. Opel owners are, uh, frugal, and wouldn't spend the necessary $3500-4000 up front to built a kit correctly, so if I supply the hardest part (the manifold) the rest of the components can be built up over time without breaking the bank. This project holds more value to me than buying a computer.

    A GT chassis is too difficult to fit unless you do some cutting to the engine crossmember and relocate the engine mount. Not enough room to fit it efficiently, and without 'cooking' adjacent components. Not that it couldn't be done, but it wouldn't be 'bolt on'.

    Bob
    Last edited by RallyBob; 06-14-2007 at 06:40 PM. Reason: added link to Garrett specs

  22. #180
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    Quote Originally Posted by RallyBob View Post
    I am going to build that Opel turbo 'kit' after all, and will prototype on my own car. Basically I will just build a manifold that fits the Manta/Ascona chassis, and will create an instruction sheet to build the rest of the system yourself. Opel owners are, uh, frugal, and wouldn't spend the necessary $3500-4000 up front to built a kit correctly, so if I supply the hardest part (the manifold) the rest of the components can be built up over time without breaking the bank. This project holds more value to me than buying a computer.
    Bob

    that's another super news Bob!
    I recently purchased a MantaA,
    so I'll be glad to buy your turbo manifold!
    Hiro

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