Real Fiero Tech

Shaun41178(2) wrote:anyone have a gen 2 fuel rail they want to donate to science?

They're plentiful in the junkyards..
The Gen 2 rails are the ones where the front and rear banks have seperate rails right?

Shaun41178(2) wrote:There is nothing wrong either with having hte injector near the valve. Modern efi allows great atomization even with the injector close to the valve. Further away is proven to make less power and use more fuel. Why do you think manufacturers are going to direct injection? It uses less fuel and makes more power.

You are right, there is nothing wrong with it, but there are better setups for all out high RPM racing. Modern EFI does allow for good fuel atomization, but could still be better. You are wrong here, further away has been proven time and time again to make MORE power. It may also use slightly more fuel (Though I don't quite see how), but it makes more power at the same time. Manufacturers are going to direct because the goal isn'tmore power. It is better emissions, more torque, smoother drivability, longer lasting emissions, and slightly more power where possible. With injectors in the air horns you'll have to idle at 2000rpm, and this isn't acceptable on a factory car. If direct injection made more power, you'd see it on today's highest tuned engines, aka streetbike and F1 motors. Yet both of these have injectors mounted in the air horns (Most streetbikes have dual injectors, one after the throttle plate and close to the valve so they idle around 1500-2000 and smoothly, and make smooth low end, and the other up top for the high end power gains). F1 uses a single injector per cylinder, but they also idle at 9000rpm.

Also the guy I bought the parts from spun his motor to 7800. Blew three motors though. Spun cam bearings in the block. bottom end survived, but the cams which I now have were just too big and spun cam bearings ruining the blocks.

I never said it would not be good for high RPM, I said it would not be as good as it could be.

aaron wrote:Manufacturers are going to direct because the goal isn'tmore power. It is better emissions, more torque, smoother drivability, longer lasting emissions, and slightly more power where possible. With injectors in the air horns you'll have to idle at 2000rpm, and this isn't acceptable on a factory car. If direct injection made more power, you'd see it on today's highest tuned engines, aka streetbike and F1 motors.

Audi R8's used direct injection.

Aaron, go back and read Shaun's initial post. The intake came with 6" velocity stacks and horns.

The high injector location is not for atomization. It's for charge density. The latent heat of vaporization of the fuel cools the charge and makes it more dense as it enters the intake tract. This technique uses more fuel because it is essentially a wet manifold and there is more opportunity for the fuel to condense on the walls of the intake tract.

At any rate, there is more power to be made by mounting it up top.

In addition, the atomization is going to be better having the intector mounted atop the air horn vs pointing at the valve stem. This may not be the entire reason for the power increase, but it is partially.

I know it came with long velocity stacks. In fact, I said this: "thank God for the tall velocity stacks" But that still doesn't deny the fact that the runners are significantly shorter than the factory 2.8l manifolds.

aaron wrote:In addition, the atomization is going to be better having the intector mounted atop the air horn vs pointing at the valve stem. This may not be the entire reason for the power increase, but it is partially.

No. Compared to injection pressure (45+ psi), extra charge motion has very little effect on atomisation. Carbs and TBI need charge motion for atomisation because they inject fuel at 6-15 psi.

I know it came with long velocity stacks. In fact, I said this: "thank God for the tall velocity stacks" But that still doesn't deny the fact that the runners are significantly shorter than the factory 2.8l manifolds.

...which are universally agreed to be too long.

will wrote:

I know it came with long velocity stacks. In fact, I said this: "thank God for the tall velocity stacks" But that still doesn't deny the fact that the runners are significantly shorter than the factory 2.8l manifolds.

...which are universally agreed to be too long.

True, but I think cutting runner length in half, and increasing the diamater God knows how much, may be on the upper limits of too much.

Go with math & physics, not gut feelings. You haven't built enough intakes from scratch to go with gut feelings.

The Dark Side of Will wrote:Go with math & physics, not gut feelings. You haven't built enough intakes from scratch to go with gut feelings.

No, but I have seen first hand the differences that 3-4" make, and it was pretty significant.

aaron wrote:
No, but I have seen first hand the differences that 3-4" make, and it was pretty significant.

so those pills worked for you?

p8ntman442 wrote:

aaron wrote:
No, but I have seen first hand the differences that 3-4" make, and it was pretty significant.

so those pills worked for you?

Hahaha :rotflmao: It really was a penis mightier.


Anyways, no, I noticed the difference going from LD9 intakes to a Q4HO intake on a 2.4 DOHC (About 2 inches shorter, double plenum volume, and 6mm bigger plate), and on my DOHC (4" shorter, also double plenum volume, and 13mm bigger on the plate). It provided a pretty noticable low end hit, and raised the RPM that the motor starts coming on by about 500-1000 easy. Unfortunately, do to bad tuning it dropped power off still pretty erly (6500).

Can you get better pics?

I am behind you 100% with this build. Totally awesome.

not till I get a better camera. Sorry.

Oh you lucky fucking bastard.. And here you get jelous at me having too many toys.. HA! who's the bastard who has a alum block and ITB manifold!

Very nice toy. Hmmm. Wonder what it would be like with my 3500 block/2.8L crank engine setup.

How much would one of those rare-as intakes go for?

v6h.o. wrote:Oh you lucky fucking bastard.. And here you get jelous at me having too many toys.. HA! who's the bastard who has a alum block and ITB manifold!

Very nice toy. Hmmm. Wonder what it would be like with my 3500 block/2.8L crank engine setup.

How much would one of those rare-as intakes go for?

Judging from him putting it up for sale, I'd say about $1500.

But that isn't a bad deal at all. It will bolt up to the heads, and that is more than I can say for mine. His already have a filter arrangement as well. Mine definately require fabrication, and I'm hoping the final cost will stay under $2000.

$1500 is a good deal for this....put it on eBay with a reserve and see what happens

donk_316 wrote:$1500 is a good deal for this....put it on eBay with a reserve and see what happens

It certainly is. I wouldn't do Ebay personally, I think it'd be easier to get rid of via the forums, and for better money. It isn't liek this is a bolt on performance part (Though not that far off).

Out of curiosity Shaun, what are the diameter (in mm), of the throttle plates? Does it have injector bungs? How about a fuel rail?

uhh actually you would have better luck on the NON Fiero forums.

[quote="aaron
Out of curiosity Shaun, what are the diameter (in mm), of the throttle plates? Does it have injector bungs? How about a fuel rail?[/quote]

Roughly 48mm. It came to roughly 1 and 7/8th inches when I used my tape measure.. No fuel rail but I think a gen 2 could be adapted. The fuel ports are evenly spaced apart so a gen 3 rail wont' work, or fab up your own fuel rail from components you can purchase from Summit. It doesnt' really have bungs per say, just metered nozzles.. It appears to have plenty of meat though to drill out to the orifice size of an efi injector though.

picked up a new camera so I can get some new pics up if you guys like. Also Will if you want detailed pics of anything just let me know. Might help you get yours up and better assembled.

http://www.shaun.saturnet.net/pics/Fier ... parts5.JPG
http://www.shaun.saturnet.net/pics/Fier ... parts6.JPG
http://www.shaun.saturnet.net/pics/Fier ... parts7.JPG
http://www.shaun.saturnet.net/pics/Fier ... parts8.JPG