Improved Iron Head Intake

[camaroyoungster]

Hey guys, I'm new on here but I just wanted to post up a thread about an intake manifold that I am in the process of making and such. I started it on http://www.thirdgen.org/forums/v6/711278-intake.html
but I thought I might post it over here to see what you guys have to say about it. Background story about the project is:

I have noticed that there are not a lot of options for our cars in terms of intakes. There is the truelo intake but I don't really like how it looks. So I am starting a thread to make my own intake. This isn't going to be a pizza box intake because I plan on shortening the middle plenum runners and making the whole top narrower. Pretty much anything is better than what we have now and I want to experiment to make an attractive looking intake that also works well.

My plan is to make it almost a cross between a stealth ram top plenum and super ram runners bolted to the stock base. I also want to be able to use stock gaskets and be able to take top off when needed which you can't do with the truelo intake. I also want to run a tpi twin throttle body but I'm not sure if that will mess up idle speed or what not. Right now is to get manifold done.
I attached some pictures of what I have so far. Templates are rough and are made out of cardboard even though I probaby should have used card stock.
This will be a learning experience for me because I am going to be learning how to weld and stuff like that and making sure everything is good. I will literally be making this out of scrap steel I have laying around and if it works, possibly build another which is more refined. If it doesn't work, I have nice "have it your best shot" trophy.

I attached a photo of what I want it to look like somewhat.

[ericjon262]

Looks like a headache to me. not to say there won't be an improvement, but the heads still hold the engine back. a guy on fiero.nl made something very similar to your design I don't remember the results though.

[Superdave]

Agreed^

I'd go a step further and run the plenum right into the heads with better sized and shaped runners, Look at the Edelbrock Pro-Flo XT EFI Intake.

You can probably cut up a stock base and then just use aluminum to make the new runners and plenum.


While the current design will be more attractive I can guarantee that the difference in performance will not be worth the effort involved. It'll be a fun project either way though.

[Guest]

While the current design will be more attractive I can guarantee that the difference in performance will not be worth the effort involved. It'll be a fun project either way though.

^^ This

The intake has never been the issue when it comes to the performance of a gen1 engine, it has always been and always will be the heads themselves.

With the ease of swapping to a gen3 top end I don't understand why anyone would bother with trying to make anything new for the gen1 engine, especially a new intake.

The design you are trying to create is more appropriate for a higher revving engine, well, higher revving than what the gen1 heads are really capable of. The stock (MPFI) intake has always seemed to work best with the gen1 heads, because the longer runners promote low RPM torque and the iron heads seem to be pretty matched to that.

--==EDIT==--

After looking at your mock up pictures on TGO, what you're going to end up with is basically just a different upper. The changes you're going to make to the mid intake is so small you likely won't see a difference from that effort. The top will end up being similar to what is called the "pizza box", but maybe a little larger, that may help a very small amount with throttle response.

[camaroyoungster]

reply

A side by side comparison would show that the runners are at least 2-3 inches shorter than the stock runners and upper. And superdave, the problem with making them go right into the head is that there needs to be a way to allow the injectors to spray into the back of the intake valve or do they? And I am sorry if you guys are frustrated with this but, a gen3 top end swap isn't in the picture right now, since I just got the engine rebuilt 2 years ago and would be worth to take it apart again and swap out a top end. that would be ideal though. I also plan on this being a learning experience with fabbing and such that might actually help since I don't want to be sitting around all winter wanting to work on my car but can't.

[Superdave]

It's been a very long time since i've had a Gen 1 intake in my hands but going off of pictures on Google it looks like they tried to aim the injectors into the port the best they could. They probably spray right at the hump.


If you go with a runner that looks more like that Edelbrock, you might be able to put the injector bungs on the back side of the runner and still maintain a similar angle. you might have to make a new fuel rail or modify the stock one though.



Correctly sized and tapered runners along with rounded runner entry points, injector angle and correct plenum volume are key to making a good one. Runner length should be calculated based on the cam specs, head port flow specs and displacement. These are things that the guys making the pizza box intakes and Truleo don't dive into. Also the straighter the path for a dry EFI intake, the better. Sharp turns just create turbulence.

In the end TheSixRavenShooter is right, the port flow of Gen 1 iron heads is the bottle neck both in and out. Until you upgrade that expect only marginal performance changes. Most of the time you are just moving the power band around, not really increasing overall power.


If you want to try something cool, grab one of those dual plane carb intakes for the iron heads and drop on a TBI unit. With a little change to the wiring and some tuning you might be surprised at how well TBI does.

[Guest]

intake design looks familiar

[geoffinbc]

If you want to do it for fun then go for it. It is good practice and never hurts. Like everyone said above don't expect the bolts holding your seat down to rip through the floor boards.

I myself have a couple 3.4L SFI intakes and a Fiero tntake that I may cut up to put a TBI top on and see if longer runners will help make me some low end grunt. I wont cost me a dime so why the hell not right? I guess one thing about no having aftermarket bolt ons is that you get to be creative.

[camaroyoungster]

Haha yeah exactly right. Just being creative. Well I am waiting for some metal to actually start on making it so hopefully I will get some pics up soon.


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[Guest]

saw this on ebay. Looks like the design you were looking to make. This one is already done. No this is not mine, I can not answer any questions on it but it looks good.

http://www.ebay.com/itm/Fiero-Custom-Intake-/301420165306?pt=Motors_Car_Truck_Parts_Accessories&hash=item462e0ab8ba&vxp=mtr

[geoffinbc]

WOW is that price for real?

[34blazer]

ugh....

Doesn't even look like it has been installed on the engine, probably figured out it's not that great and is trying to hock it to a poor sucker.

http://www.fiero.nl/forum/Forum2/HTML/128944.html

[camaroyoungster]

That is pretty crazy priced. Does it realy effect atomization if it isn't aim exactly at the base of the intake valve?


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[geoffinbc]

Depends on the intake. I have seen them basically at the port entrance to the head and others at the intake runner entrance near the plenum. Some intakes have the injectors pointing backwards against the direction of flow. I guess only flow testing and the dyno can give you the true answer for each intake.

[camaroyoungster]

I was wondering because If I ever wanted to improve it any more. It would be very hard to direct it towards the base of the intake valve and I know that carburated and tbi engines obviously don't go right into the port. I do have some updates just some small ones for right now. I have the general ports and shape cut out with a plasma cutter and the mounting holes drilled. I need to clean up the shape and the ports obviously when you see in the pictures. I might not have a lot of updates this week because of finals but once break starts I can really get going on it. For this intake to work I think I am going to have to use a 3.4 rwd fuel rail since it doesn't have the fuel block and the fuel lines go straight out the back.