First step toward turbo

There is a thread in pennocks that I got this from...there are a bunch of guys with cut down runners. They say they are getting better low and top end performance.

I don't know too much about design on intakes, but I suspect the low end performance comes in the decreased resonance point because of the shortened runners, and the top end because of removing the obstruction in the upper intake allows more total airflow. Also, there is a height issue if it gets too tall. And cutting the middle eliminates one 90deg ish turn the air has to make in the middle plenum.

That was the long answer. The short one is someone did it before and had success, so i don't want to reinvent the wheel.

As for the above...totally agree!

Chay

Chay, I don't remember the name given to this technique/addition, but had you looked into adding "extensions" to the runner tubes where they enter the plenum? They stick up a bit from the floor of the plenum. It's supposed to help flow. Do you know what I'm talking about?

Okay, don't laugh... I tried to draw it for you. The runner with the extension thingy is on the right. The shape isn't right, but it should be good enough to get the idea across.

Dr.Fiero wrote: So....  Short is good.

Keep in mind I was only wondering why Chay cut the last inch or so off the runners.

 

I made note of the discontinued Truleo...when all arrow point in the same direction it makes decisions like that easier.

C

Looks like all the pro velocity stacks have a bevel on the inside...so I'll bevel the runners before I weld them into the plenum and it should accomplish the same thing. Good tip.


Chay

Ok, for injectors...here we go...

There are two measurements which are important. The grove to top height and the grove to bottom height. Then, there is the flow, in CC or in pounds/hour. 500cc is about 49 lb/hr, so you can convert.

Also, there is the injector impedance to consider.

First, the group of injectors I'm messing with:



How did these get upside down??? Ha ha. The left is a LT1 injector(24lb/hr)...I cut the top groove, the bottom is stock for reasons you will see below. The second is a 1996 3.8L dodge injector(22 or 24#/hr), a Siemens Deka 666A. the third is a 1996 3.0l dodge injector, a nippondenso INP-066 (19 OR 20#/HR) and the last is the Fiero stocker (14#/hr).

More on the stockers...



2.42 is the body length, and is critical because this is the distance between the fuel rail and the lower manifold. If this isn't right there is a good chance you will have vaccuum leaks and it won't seat in the lower manifold far enough for a good injection into the air path.



This is the ring groove to top measure on the stocker. this will fully insert the top on the injector into the rail. The port is cylindrical to the end where there is a small bevel to ease insertion into the rail. as long as the o-ring is past the bevel, there is no difference in sealing from there on up. This allows a smaller groove to top dimension to be used, which allows many injectors to interchange.

Nipondenso (19-20#/hr):




The body height is the same so this is a good candidate. How is the groove to top height?



At .37, it's smaller than stock (.43), but should still easily seal. This is my fall back set of injectors. They are high Z so no problem with the ecm.

Siemens Deka (24#/hr):



2.25", uh-oh. It's a no go. Too bad, the #/hr is what I'm after.


Ok, LT1 injectos (GM 2561462, Bosch 280 155 931) at 24#/hr. These are rated at 28#/hr, but at higher pressure, so they are at about 24#/hr where I want to run (44psi or so).



You can see the original groove (Lower) and the groove I made. From the groove I made the body length is perfect (.02" difference, no big deal). So how is the g-top measure...



.36, not bad, not super good. It will seal though. It's a very similar measure to the nippondenso.

Here is a few shots of the rail and lower manifold:



Stock vs LT1



Stock vs nippondenso





LT1 vs stock



Nippondenso vs stock



LT1 (disk pattern) vs nippindenso pintle


Chay

One day.

When I was over there I never made it though. Too much family commitments.

I did up the runners, as best I could. The pics don't really do it justice, but:



Sort of trumpetty....I made sure the corners were very rounded and smooth.



Will it work? Who knows.

Chay

Flow-bench numbers for Stock intake and SR14 & LR17 below.

Valve lift	.100"	.200"	.300"	.400"	.500"
stock intake CFM	55.945	106.88	124.415	131.93	139.445
Discontinued: Trueleo Long runner CFM	59.786	111.055	130.26	144.455	146.125
Trueleo Short runner CFM	62.625	114.395	133.6	146.96	146.96
no intake-head CFM	64.295	116.9	133.6	146.96	146.96

After doing a bit more research I found lots of V stack pics. They have bigger and more circular radiuses, but mine will work somewhat. It's better than not doing the shaping for sure.

With our oval and disimilar shaped runners it will be hard to get anything comercial to fit, so shaping the oem seems to me the best solution to keep it simple.


May of the V stacks don't extend that far into the plenum, so I'm going to try 1/4-1/2 inch.

Chay

The shape of the plenum will be the same, it's just that it will be assembled in a way where I can work the interior. It's a space issue on the top of the engine. Too big a diameter and the trunk lid will hit.

I think the size is adequate:



As you can see the throttle body fits ok (It's big enough). The junk in the interior is from drilling the corners of the runner entrances.

This time I will start with doing the flat piece. I will cut out the runner entrances and then insert the runners, tack it in place and then build the horns on the 'inside', the to finish it, weld on the tube section. This will help 2 fold:

1) The runners enter at an angle, so I can weld to fill the gap left by the angle on the inside

2) I can build better V stacks because I can make them bigger and shape them better, and have access to machine them

This is what I have in mind as a model (It's a bit fuzzy).



It'll end up somewhat different (More horn type than trumpet type), but that's the idea.

Chay

Found what I'm looking for: HERE