Fabricating Aluminum Intake Manifold, need help
Hello all and Happy Holidays.
I have a stroked Volvo B20 engine that I am building and will be turbocharging and I am looking into fabbing a new intake manifold out of aluminum, yes I do weld aluminum.
My question is about tuned port, pressure waves, runner size to name a few. A cursory search found this article, http://mysite.verizon.net/vzezeqah/s...ionsystems.pdf
Volvo does have a Fuel Injection manifold that I can use, but space will probably be an issue, hence the idea of creating a new intake manifold to make more room for the turbo.
This article points to pressure waves and equations for, as far as I can tell a NA engine. Do the same principles hold true for a Forced Induction?
Any help or direction is appreciated.
do you think it will make much difference in the end?
Yes longer runs make more low end power but shorter ones respond gaster giving good snap and make the car more responsive even if it gives up a few hp it gains it back in a quicker charge to redline.
Most people use the Q45 throttle body its 95mm. That usally handles any engines needs. But you cant really go to big for quick reving engine. Smaller engines need more attention paid. But throttle plate can still be pretty large if the ports are the right size and shape.
In short to answer your question, yes but NO in the real world since you will never know the difference ones you blow on it. Boost will over come bad port shapes and too small a hole. Just make it bigger than it needs to be sep nice smooth taper into the port. A properly tapered port will make more power than any pther mods you can make.
Thank you for the replies.
Because the intake and the exhaust are on the same side I have been wondering about throttle body and plenum on the other side of the engine with the runners going over the top of the valve cover and then doing a 180° to the intake valve. I am a little leary about the 180° turn.
Here is the stock intake look. With a turbo in there it will be tight. http://www.1800philes.com/images/rebuild/side.jpg
This is from another forum, but the basic design of what I am thinking about. http://i22.photobucket.com/albums/b3...28etIntake.jpg
In my opinion, tuned port, pressure waves and runner size can be tossed out the window when you go from naturally-aspirated to turbocharger-aspirated. All you will need is a plan to deliver the proper air/fuel ratio to the motor and a way to keep the charge cool. In your case, using FI simplifies keeping the A/F ratio in line. I like your "over the top" runners, same as the intake system on my old '91 Ford 300 six cylinder motor, but I think if I were doing it, I would fabricate an intercooler to fit in that space also.
I understand that you have little room on the driver's side for the turbo unit, but weigh making room there by doing a little surgery on the existing parts against running exhaust tubing to the other side of the motor to run the turbine. I have made the comment many times that with a cutting torch, a Sawzall, a MIG and a good hand grinder, you can make anything fit anything.
I think if I were doing your project, I'd mount everything on the driver's side by doing some surgery, then I might mount an air-air intercooler down low in front of the car.
I'm certainly not the forced induction guru on this board, just presenting a few thoughts......good luck.....:thumbup:
My CR is going to be right around 9:1, with a turbo I know that is higher than recommended. Can I place knock sensors on the engine to prevent detonation? If so, where on a loud and noisy 4 cylinder would be the best place?
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Now, this is with hot air. I'm thinkin' that with an intercooler, you could use more boost without detonation.
I have little experience with knock sensors, being from the old school and reading spark plugs to get the tune right. I'm sure that most of the high-tech world has passed me by though. A little surfing on the web found this offering that may interest you.....
J&S Electronics SafeGuard Indivdual Cylinder Knock Control
As far as reading plugs, buy a 10X lighted exam tool, chop the ignition and coast to a stop after a power run and examine the plugs.
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long time ago.
50 years ago my engineering college project was designing a tuned injected manifold, as I remember tuned length was calculated using temperature , density and cam and rpm for max horspower. to get the numbers right. But I needed more money to finish college and sold my roadster. but I did get an A on the design project.
I would copy the stock intake out of larger 1/4 thick wall alumiunum tubing. Use 3/8 for the flange and make the log the same size or larger than the charge pipe or turbo outlet.
Throttle body can be on either side use the intercooler to move from one side to the other. Put the turbo low and allow the charge pipe to snake around as needed. Looks like you could run the chargeipe out the turbo and down under to the left side and into the cooler and out the right side and up to the throttle body pointed in some direction that fits with as little angle as possible. Make any 90 degrees right angles at the throttle body and use the silicon 90 to make a smooth bend. Not perfect but will make crap load of power before its an issue. If all the charge pipe is 3" and intake log at 4" with 2" id runners tapering into the port as smooth as possible you should be able to support any hp a normal build up of the bottom end could support. Sometimes i have used thicker wall pipe and ported the shape needed for oval and strang eggplant efi ports.
Hope this helps cant really give anything exact because im not under the hood. But i will tell you crappy charge pipe will still make a boat load of power and can always be cleaned up or hidden. Buy some charge pipe kits with lots of J bends and a hack saw and get to work trying to make it fit then built the last part of the intake and make it all match up.
Also if you use a large pipe for the log part of the manifold you can cut it out and add a flat plate to clear the headers. Just leave room for a heat shield. Without it stock manifold could make more power because of charge temps and boost leves that can be support with lower intake charge temps.
If i was going bannas with a 4 banger i would use itbs and a log type collector for boost. I have a system like this i am welding up for my civic. Should work good its a much bigger hole than before and i plan to up the boost alot along with it.
I am also planning on reinforcing the runners by welding some 1/8th inch between the runners, like webbing. The flange I agree needs to be at least 3/8 inch.
Inside the intake/plenum should I run air horns or just smooth it down with the same idea of the air horn?
Thanks again for the input!!
IMO I would keep inside diameter the same and go fairly thin on the tubing especially with gusseting; no sense in adding weight. The tubing gauge from the early 90's Geo Prizm/Toyota Corrolla intake should be fine. You may want to look up some photos of these manifolds as it could be an alternative to the over the top (which is a GREAT design and will yield good low end torque prior to boost).
The engine will be used for low end accelleration/cruise, not just boost and a good normally aspirated design should be adhered to for optimization over the entire range. Log style exhaust manifolds should be avoided as well.
the runners support a lot of wieght and using 1/4 inch thick wall pipe is usally the best way to go. but 1/8 will work as well if its gusseted up correctly.
Flow will come from much bigger holes. no need for air horns or other stuff since this is turbo it will flow a massive gulp of air everytime the valve opens. You just want to make sure that gulp is not going to be too far from the valve.
I would try to double the ID of all pipes in the intake if at all possible. Best to go too big too small will hurt performance where too big just makes it flat on the bottom end. Until the boost hits then it just needs room to breath.
I would try to slip in shorter runners. The stock ones look very long and will surely make the engine work to get its gulp of air. But I am not sure if you have any room for those types of changes.
what cam/s do u have in the engine and what size turbo charger
whats the engines redline and were do u want it to make the most power
on my 2.8L turbocharged v6 engine i picked up 28hp and 35ftlbs at the rear tires with a manifold i made for it
i shortened the runners 3 inches and and increased plenum volume almost 2.5 times over stock
the plenum volume increase helped it pick up power uptop but made off boost,low rpm driving responce a tad sluggish
here one o fthe ones i built . i reused the stock lower and middle section but did a whole new top
heres the cutup stocker
and what i made
urs will be much simpler to make over what i made for my car
for the plenum u want a flat bootom were the runners meet it, and u want all entrys bellmouthed , then use a half round plenum , u can tune runner lenght a lil bit to fine tune the intake
what i would do is make the plenum bolt to the runners , so u can make 2-3 diff sets of diff lenght runners and see what works best
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