Rick@Synergy

iTrader: (5)

Ok, so I was on the dyno all day today racking my brain on why I am not getting anything out of the VIC JR over the 90/90 setup. Granted its most likely the tuning right now, so thats where I hold my questions....

Do I need more timing or less timing. Trying to think like an old schooler on the design of the VIc JR, but also trying to think LS1 cylinder head. It seemed to do better with alittle more timing, but not much. Still way down from the old setup. So does anyone have any dyno time with this manifold at all either? I know for one thing it liked alot more timing at idle. It smoothed out real nice once I hit around 40-42* at idle. And I got better vaccum on it too.

Rick

Old SStroker

Question: what's a "90/90"? The only thing I can think of is a 90 mm TB on a FAST 90. If this is an LS1, look at the current Hot Rod mag. They ran a Jr. vs a RPM 2 plane, but not vs. an OEM style manifold.

Whatever the engine, shouldn't you match the valve timing (cam) to the intake style and lenghts to maximize the tuning?

Rick@Synergy

iTrader: (5)

Yes, its a 90tb on a fast 90.

I figure I had a big enough camshaft, 230/234 114 that I could see something from this intake. But maybe I am falling short of this now?

Rick

stevemilz

iTrader: (3)

Id like to know also. Im starting the process of going through my motor. I didnt want to buy a Fast 90/90 setup again. I was thinking about a Victor Jr. with a Accufab 4150 style throttle body and a T-Rex(again). If I had to take a stab in the dark I think your cam is a little small(I hope the T-Rex isnt). Ive done a couple searches and it seems this intake is for big cube motors and solid rollers. If you find out let me know.

hellbents10

iTrader: (10)

The problem is the runner length of the vic jr vs. a 90/90. The shorter runners on a vic jr. will not help you but rather hurt you cause of the smallish cam and not enough cubes. To benifit you would need more of a airflow requirement at every givin engine speed. If you had a form of forced induction the shorter bigger runner and the plenum volume would help you lower IAT's cause of the better airflow, thus you would have more timing, less restriction and you would mek more power everywere in boost.

I think if you had a much larger cam in there you would benifit with the cubes you are working with.

Old SStroker

I don't think it's about cam "size", but rather intake tuning for the rpm range you want to run the engine in. The LS Vic Jr. has long and short runners which are shorter than the FAST, so you might see less low and mid range and more higher end with the Jr's shorter runners. Then again, you might not be willing to run the engine to the revs where the Jr may do its best.

IMO, you need to treat the single plane (Jr) LS engine as a very different engine from the LS with OEM/FAST folded hands intake. I'd get a cam/engine designer to do a cam for the engine and it's intended use. My guess is that the 114 LSA won't be in the new spec.

My $.02

HALLZ

iTrader: (1)

Is this test on small 347?

I would "think" a 108-112 lsa with 240+ dur and 370+ CID is were the gain would be seen. Along with some form of power adder were the increased velocity is needed.

just my $.002

DAPSUPRSLO

iTrader: (14)

Just a suggestion, what do you guys think? Wouldn't you want the intake valve to open a good bit earlier with a carb intake to take advantage of the wave tuning which will occur at a much much sooner point (in relationship to intake valve opening, not rpm) vs. the long runner lsx manifolds??? Plus, with the intake extending the rpm range out so far I don't think you'd find any negative results by closing the intake valve sooner as well. Just a thought and open for comment.

HALLZ

iTrader: (1)

Along those lines wouldn't injector timing change then also??

DAPSUPRSLO

iTrader: (14)

I'm certainly not certain HALLZ but I wouldn't think there would be any requirement for alterning the point the injector opens and closes, maybe how long it stays open as dictatated by the now different volumetric efficiency of the motor, but not the open/close point together.

DanZ28

iTrader: (5)

For this test, I wouldn't think cam size or cubes would be the factor in such a huge difference in HP and TQ from just pulling the FAST 90/90 off and bolting on the Vic Jr, thought it might at least even out on top. I was more expecting the area under the curve to be different. I do see where it would benefit bigger cubes and bigger cam over this setup though and especially FI. The motor was built to rev, but the cam is the limitation in this senario, so we just went to 7K RPM.

Dan

Ryne @ CMS

iTrader: (10)

we flowed a victor jr. intake, it only flows 275 ish cfm, on a head that flows 315 cfm, plus the short runner on top of it, hurts you everyway possible.

HALLZ

iTrader: (1)

Dan or Rick
Did you guys match the intake to the heads, they are pritty far off right out of the box!!

Ryne,
That was a head and intake flowed together correct? Were they matched ported or box stock?

Patrick G

iTrader: (14)

Most dynos I've seen with a single plane intake on a 346 have been disappointing. Some of it is because the manifold had a restrictive elbow on top, limiting total flow, but a lot of the poor performance comes from running a cam with too late of an intake valve closing point.

All you have to do is think about how you'd tune a 346 with a single plane and a carburetor. You would not run a 114LSA cam in it. It would probably be more like a 106 or a 108LSA cam bringing an earlier IVC and better dynamic compression. Try swapping a 230/234 108LSA, 108ICL cam and see how it does then. Bet you pick up a lot of bottom end (with better valve events) and pick up top-end with better breathing.

HALLZ

iTrader: (1)

People say I am nut and think I am crazy when I mention what you just did. A 108 or 106?.... Then they dismiss anything said afterward l(lol) Besides,.... "how will you get it to idle" "you will bleed off to much cylinder pressure on the bottle like that!"

Not to mention who puts old technology on a LS1??

Dave88z

Patrick your thinking seems to be in the ball park. When Allan at Futral e-mailed me he recommended using a 239/243 110 LSA+4 w/my victor jr and Dart 225's.
Although it will be on a 6.0L engine.

DanZ28

iTrader: (5)

We can't really move it beyond what the mounting bolts allow it to. why would they be far off, they looked to be ok? As far as porting it, no, it was a straight swap out for this experiment. I could always put the trex back in.

HALLZ

iTrader: (1)

If I recall correctly Chris's was almost .20" off on some of the ports, I should have taken pictures. Plus did you notice how small the mounting bolts were compared to the holes in the manifold? I wonder if it could shift causing any flow problems or obstructions??

HALLZ

iTrader: (1)

Found some,...Look at the floor of his before matching it

Rick@Synergy

iTrader: (5)

Looking at the pics it looks like you had to port the head some more versus porting the intake because it looks like the manifold sat lower than where the floor of the head was. Am I on the right track? Do you have pics of it after wards?

rick