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Old 02-01-2003, 03:43 PM   #1
Tattoo Collector
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Default Custom Intake Manifold (gauging interest)

My professor and I are about to start designing and testing a custom intake manifold that will flow better for the 98-01 Impreza RS. I wanted to see how many people would be interested in something like that and how much people would be willing to pay. I know that the stock intake manifold is super restrictive and a ton of power could be freed up from a different manifold; this would be especially good for those who have some headowork or cams. The manifold will be a full custom sheet metal manifold. It will be designed and tested on my heads. We will be using the flow bench to do everything, so we will have real flow numbers, not just some shot in the dark about how much we think it will flow.
My professor that is helping me design this manifold is a designer for ford's engine race development stuff (SVT Focus, Contour, Mustang/Cobra, etc) and holds over 20 national and world titles with the engines he's built and designed. One engine that particularly grabbed my attention was the 1.6 liter turbo'd Ford Cosworth that put out 1000 horsepower and was still strong enough to race around a track for an entire season! (until it was banned) And that was back in 1989! He has all the tools and a state of the art facility, so this will be tested to the highest degree.

Please give me some feedback on who would be interested in this.
Thanks.

Nathan
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Old 02-01-2003, 04:36 PM   #2
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Pending price, i would be interested.

Cameron
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Old 02-01-2003, 05:49 PM   #3
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Tattoo Collector - There's 2 words for you -> "Good Luck" The MY98 RS uses a Phase 1 intake manifold, whereas the MY99-01 use a Phase 2 intake manifold. There won't be a "one size fits all" type of application for the intake manifold.
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Old 02-02-2003, 01:09 PM   #4
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Quote:
Originally posted by GTBGUY
Tattoo Collector - There's 2 words for you -> "Good Luck" The MY98 RS uses a Phase 1 intake manifold, whereas the MY99-01 use a Phase 2 intake manifold. There won't be a "one size fits all" type of application for the intake manifold.
But getting around the mounting flange differences and the idle air hole differences between the two...the overall design could still be similar and usable for all of us.

I would pay for a design that worked very well......don't make too many comprimises for streetability and those who buy them for all out performance will thank you.

Jay Storm
www.sourcemotorsports.com
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Old 02-02-2003, 02:31 PM   #5
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I would be interested too, just depends on the price.

Good Luck.....sounds fun
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Old 02-02-2003, 09:05 PM   #6
Tattoo Collector
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I am also worried about streetability, but like I said, the guy that's helping me is the person that is directly responsible for things like the SVT motors, some cobra motors, etc. They all have to run on the street and they do so with a MAF sensor. I know everyone is worried about price. These things aren't going to be dirt cheap. A lot of time on machines and development, testing, etc. has to go into them. Please give me some ideas on how much people would be willing to pay, that way I could talk to my professor about how much he thinks we could do it for. Also, post any concerns anyone would have with the production of something like this. (EX: Design changes with the different years)
Thanks.
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Old 02-03-2003, 02:33 AM   #7
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Quote:
Originally posted by Tattoo Collector
I I know everyone is worried about price. These things aren't going to be dirt cheap. A lot of time on machines and development, testing, etc. has to go into them. Please give me some ideas on how much people would be willing to pay, that way I could talk to my professor about how much he thinks we could do it for.
Off the top of my head, depending on the flow numbers, i would say $4-500.
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Old 02-03-2003, 04:15 AM   #8
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Between $250 - $399.

Keeping or increasing the bottom end torque is very important to me since I have an automatic and don't brake torque at every stoplight to get the revs up.

Gary from Compass Motorsports had the right idea when designing their intake. It made the most HP and TQ of any intake to date and was actually dyno tested. Unfortunately he never released it due to the amount it would have cost.

For some reason I can't get to his website (www.compassmotorsports.com) but the intake was an aluminum box at the throttlebody and then a 2.5" to 3" tube running from the box to the fender for cold air. It made somewhere between 10 - 14hp and about the same torque (it's been a while so those numbers might be off a little).

OK, I just found a pic of the intake:
http://www.geocities.com/subystyle/projectsandnews.html
This site seems to be a little old because they did do a dyno run and posted the results on the I-club a long time ago.
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Old 02-03-2003, 11:16 AM   #9
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Default Not an Air Intake

Just to clear up any confusion. This is not going to be an air intake. This is going to be the Intake Manifold that you would bolt the throttle body to the top of and then it would bolt down to the heads. I might also use a modified throttle body from a different car and just modify it to use the stock TPS. Hope that cleared things up. Thanks.
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Old 02-03-2003, 11:30 AM   #10
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i drive a legacy...but i'd love to see someone come out with a better intake manifold. it won't be cheap, though. people need to keep in mind that since it would probably be low volume that they would be paying for a fair share of R&D as well as tooling costs. i don't imagine a properly designed and tested manifold will run much under $500.

jay
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Old 02-03-2003, 01:51 PM   #11
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Default Tooling won't be an issue

As far tooling goes, that won't be a problem because the intake manifold will be made from sheet metal and we will be testing it on the heads (on the flow bench) and on a dyno. We have access to all of those things. As far as my other concerns, I still don't know what I am going to do about the people that don't have the DOHC. That is what we are going to base the design off of. Maybe what we'll do, if anyone is interested and lives in the Northern Pennsylvania area, we could have them come down and donate their car for an afternoon. Does anyone have the specs on the intake manifold for a 2000-2001 RS? (from a service manual or something of the sort) That might help out. I really just need to know what the difference is. By looking at them, I can't really tell much of a difference at all, but looks can be deceiving. Let me know.

Thanks.

Nathan
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Old 02-03-2003, 03:03 PM   #12
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Im all for the idea...the only other intake manifold I'v seen was off an airplane, and that was built for a specific RPM range (so not good for street). Under 500 is my limit.

Tho, WHY make it for only DOHC 2.5L? The SOHC is much more common, popular, and also is STILL being used today. In fact the next few years of the RS will probably still have the 2.5L SOHC. I just dont unerstand why you would make the manifold for an engine that was only used for 2 1/2 years, when we have one thats being used for just as long...and will continue to be used.
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Old 02-03-2003, 04:26 PM   #13
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Quote:
Originally posted by DDMan


Tho, WHY make it for only DOHC 2.5L? The SOHC is much more common, popular, and also is STILL being used today. In fact the next few years of the RS will probably still have the 2.5L SOHC. I just dont unerstand why you would make the manifold for an engine that was only used for 2 1/2 years, when we have one thats being used for just as long...and will continue to be used.
I'm pretty sure he is making it for the DOHC because that's what he has so that's what he has to work with design wise. He said earlier that if anyone with a SOHC lived in northern PA and wanted to bring in thier car so they could find out the differences in the SOHC design, they were free to do so. Hopefully someone with a SOHC could do that because there are a lot more SOHC 2.5s than DOHC.

Cameron
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Old 02-03-2003, 04:39 PM   #14
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Default

I agree that you should make one for the SOHC instead of the DOHC. It may cost you a bit more to get a SOHC engine at first but the extra money you will make from sales of SOHC manifolds will more than make of for it.

You will run out of customers really quick if you just do a DOHC setup

Eric
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Old 02-03-2003, 05:51 PM   #15
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If you really want to make some money from the design of an intake manifold, you'll make a reversed throttle body design for the FMIC turbo guys. As everyone knows anyone who is actually serious about making power just starts with a 2 liter turbo these days.

Once you get past that, with CARB approval, I'd pay $300....
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Old 02-03-2003, 06:11 PM   #16
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I'm pretty sure he is making it for the DOHC because that's what he has so that's what he has to work with design wise. He said earlier that if anyone with a SOHC lived in northern PA and wanted to bring in thier car so they could find out the differences in the SOHC design, they were free to do so. Hopefully someone with a SOHC could do that because there are a lot more SOHC 2.5s than DOHC.


Bingo. Maybe we'll design something for the 2.0 also, we first are doing this b/c I am doing a naturally aspriated buildup and I want a better intake manifold. We'll see how everything goes. I'll keep everyone posted. If anyone can get me some stats on the SOHC manifold, I would really appreciate it.
Thanks
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Old 02-03-2003, 06:13 PM   #17
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It'll never have CARB approval, so no worries there.

Tattoo, no offense here, but do you really think you can outsmart the FHI engineers? There are a million more considerations in the design and construction of an intake than simply flow numbers. Aside from that, it's a LOT more work than just welding up some sheetmetal (which, honestly, doesn't sound like great marketing).

You may well be able to design an intake that will outflow the stock piece, though I really don't think there will be the gains you speak of ("super restrictive" "ton of power"). COBB's already proven that most of the work is in the heads (cams, valve jobs, and porting) to get high N/A power.

Read some books on intake manifolds. Compare the manifold runner size to the valve size, then see where there is to go. The stock piece is fine until you have cams and porting and intake and exhaust. The manifold, as you describe, won't help at all unless those other issues are addressed first.

IMHO.
YMMV.
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Old 02-03-2003, 07:03 PM   #18
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Default Yes, I do think engineers can be outsmarted

Like I said in the very beginning, I am not the one that is going to be designing, testing and building this thing. The person that is doing that is responsible for some pretty amazing race engines as well as a lot of the Ford SVT stuff that you see on the roads. I will say this again; HE IS A MECHANICAL ENGINEER AND DESIGNS RACE ENGINES FOR FORD! He also holds over 20 race titles on a national/international level. He is going to be doing all of the work. I am just along for the ride b/c he is helping me out with my stuff as a class project. The knowledge he has is leaps and bounds above anything that I have ever done. For example, last week we were talking about it and he was telling me that the two BMW Z3's that ran #1 & #2 in showroom stock last year (I'm guessing SCCA) were both engines from his shop and used the oil pressure to adjust cam timing and vavling in a plastic intake manifold that varied the runner length dependent on RPM's. Those cars were pushing out 320 hp or more; and that was showroom stock!
As far as the sheetmetal thing goes, who cares what it's made out of as long as it gets the job done. I know there are a lot of people that like it to look real slick and shiny, but those are usually the people that don't care too much about going fast either. I have seen some damn good sheetmetal designs, and they even looked nice too.
Also, my engine is going to be completely done. I am doing a full port/polish using the flow bench, vavle job, cams, throttle body, full exhaust, ECU, etc. I know that I will benefit from doing this. But, like I said, I am just doing this for myself. He thought that if we came up with a good design and I thought there would be a market for it, then he would make a few of them for the public.
Finally, there is way too much negativity on this board. Everyone should embrace one another for trying to make innovations with our stuff. We're not Honda guys, that's what seperates us. We also don't have the amount of stuff available for our cars. Who cares if this manifold doesn't work either, this is just a trial thing for me and I figured that I would offer to anyone that would be interested.
What if someone told John Brittan that he couldn't build a motorcycle from scratch that would compete at Daytona? Would he still have cast his own engines in his wife's kiln in a little shop in New Zealand? Would he have designed and built a bike that was made from all his own parts (block, pistons, connecting rods, heads, etc) and won Daytona? Maybe, maybe not. I am sure there were people along the way that told him he couldn't outsmart the great designers of the time, but that didnt' stop him. Ideas are the spark that create innovation. Talking about those ideas should help that process along, not hinder it.

Anyway, to get back to things. Sorry for that little diatribe, but I think that we should all try to work together on things instead of shooting people's ideas down. I am going to make an intake for my car, if it works and other people want one, then by all means, we'll make one. The person doing this intake will be just as qualified, if not more so, than anyone who is out there designing parts for cars.

Thanks
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Old 02-03-2003, 07:17 PM   #19
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Julian--

Actually Cobb has repeatedly said that 230-240 crankshaft hp is the limit on the n/a 2.5 because that is the limit that the stock intake manifold will support. However, they have also said that a good intake manifold would be very expensive. You are correct in that a number of other mods will need to have been performed for the aftermarket intake to do much good, though.

Jay
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Old 02-03-2003, 08:28 PM   #20
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It seems like most people here are trying to rain on your parade, but if you came up with a design that could support upto, say 350 hp with head work, i'd pay a little more than $700.
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Old 02-03-2003, 10:18 PM   #21
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Default on a more serious note

The intake manifolds for our cars (in N/A form) are actually quite good. The cheaper and larger bang for the buck method would be to just get it extrude honed, add a flow coat on the inside and a thermal coat the outside.

The only real reason to re-design the whole intake manifold would be for turbo apps, as well as 1 TB/ cylinder injection type of N/A use (a la M series engines)

Save your money on lighter rods, or higher C/R pistons if you're doing a N/A build-up.
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Old 02-03-2003, 11:24 PM   #22
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Wow, you people are amazing. A simple "I'd be interested" or "I'll wait to see how this develops" would have been appropriate. Cam warned me about reading this thread as I would be pretty annoyed by the lack of enthusiasm for someone with the ability to design and manufacture a part such as this. Correct me if I'm wrong, but the majority of cars available on the market (n/a) would benefit from an aftermarket Intake Manifold, especially one capable of high horsepower applications. So it's ok to spend $300-500+ on an exhaust, $300+ on headers, but not ok to spend that on an INTAKE MANIFOLD? I mean I know it's easy to say "I wouldn't spend the money for 5-15 hp" but most of us already have! I know the boxer is a cool engine, but I HIGHLY doubt the engineers at Subaru were pushing the envelope during development. With just about any engine, there's a mod that will further enhance its capabilities, and for anyone to say "oh well, there's no need to replace that, its good enough" must think we own an '03 Cobra.

Did anyone with negative comments ever stop to think "Hey instead of making a heinous remark, I'll put this in the form of a question just to be sure it has or will be addressed when the time comes" I bet, not! Or how about the fact that maybe this mod on a COMPLETELY STOCK RS would do little or nothing for performance, but would definately be the icing on the cake should one of us choose to drop in cams, rods, and every other N/A mod they could afford to avoid all the problems associated with turbo'd ej25's?

Suba_Roo did have a point in saying people who are looking to make big numbers are switching to turbo EJ20s however I'd love to wait and see STi's reasoning on using an EJ25 for their USDM STi. This change may lead us 2.5 people to have more parts and better opportunity to design parts to accompany mods and may even lead to a rise in reliable TURBO 2.5's...oh no!

Nathan, I applaud your efforts and I'd love to hear how your R&D goes. To keep from having this problem again, I'd say just take a list of names and email addys from people who ARE interested and just keep us informed of how it goes.
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Old 02-04-2003, 01:52 AM   #23
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Quote:
Just to clear up any confusion. This is not going to be an air intake. This is going to be the Intake Manifold that you would bolt the throttle body to the top of and then it would bolt down to the heads. I might also use a modified throttle body from a different car and just modify it to use the stock TPS. Hope that cleared things up. Thanks
HAHA! I was way off! Sorry!
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Old 02-04-2003, 02:14 AM   #24
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Go for it, Nathan! I think you have a great opportunity there, so go on and grab it!

I wish I lived in USA, so I could afford that kind of stuff. Where I live, it's impossible to get even an aftermarket performance exhaust for a Subaru, not to mention real stuff like cams, valves, etc. I have yet to see someone offer a CAI for Subarus in Europe...

The OEM stuff is also incredibly expensive (a crank angle sensor - a $18 piece in the USA - costs about $150 here! ).

I wish you good luck and a huge power gain with your intake manifold!!!


D.
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Old 02-04-2003, 01:22 PM   #25
Suba_Roo
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While you are at it, check out Cobb's site, they have a pretty interesting tech article on the viablity of the intake manifold on our engines.

Barkall4 is right, that all things being equal 2.5 liters is better than 2.0 liters. However the reason 2.0 liters have been chosen for most people's big power starting block is the closed or semi closed deck. (amongst other things) STI is building a special 2.5 liter block with a semi closed deck to support the 300 horses.

Tattoo Collector do a search on intake manifolds for airplane applications and you will see some seriously cool sheet metal and tubing intake manifolds.

The thing that you are going to learn on that flow bench is that Subaru did a pretty damn good job with our intake. You will be able to make a custom intake that will outperform it in certain rpm ranges, but it will take big hits at other rpm ranges. In other words you will likely have to sacrifice low rpm torque for high rpm power.

Try and get your hands on one of those red STI intakes, you will find they are essentially identical.

Finally let me clarify what I said earlier. If you want to make some money, either make a reverse throttle body intake (preferably one that doesent sacrifice the engine accessories) for use with a FMIC and you will sell a lot of units. If you are just out to have fun, build a trick sheet metal intake, thermal coat it a cool color (or bling bling chrome that is always popular here ) and post lots of pictures.
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