The Fast restricts more power than an LS6 up top?
Dont think so.

I ran a 242 248 in my 346 last year ... not bad at all if you have a good tuner

 

I do agree though that if it's all legit I am glad Collins is sharing his info. I see it as people trying to help him out by saying his results are skewed by something wrong and then him blaming the FAST 90 though instead of actually wondering if something else is going on in his tests.

 

I didnt read the entire thread, nor am I extremely familiar with the FAST intake. But looking at it like you would cylinder heads, in a runner volume vs. velocity point of view (increase volume = decrease velocity); wouldnt it make sense that only the larger NA motors with bigger cams, sucking in HUGE amounts of air would benifit from the larger FAST intake? I think some of these 346's with smaller cams just cannot create enough velocity in the runners/ports to really see the true potential of the FAST 90/90 setup; and in some cases, even loose power.

And about the folks using the FAST on a FI setup, thats a whole nother animal there. A FI motor won't always benifit from a larger, better flowing intake when under boost. On the other hand, It COULD allow the same power to be made at lower boost levels. And in most cases, if one were to bolt on a FAST intake and change NOTHING else on a FI setup, your max boost would decrease based on the ideal gas laws, increased volume = decreased pressure. just thinking out loud here...

 

I am just sayiung there are multiple ways to make power, and there isn't a cut and dry formula on how to do it. There is a trend on the internet to turn threads like this into group lynchings. He is doing it on a 346 without a FAST. A majority of setups will gain with a FAST. Some won't. Those are both facts.

Does that make the ones that won't "bad" setups? You would think so if you read this thread. I bet the guy whose Vette he posted the graph for is pretty happy!

He didn't say that, and as far as I can tell, he hasn't tried to sell anyone anything. Please don't put words in anyone's mouth. I personally, am one cheap bastard. I see an opportunity to save money here, and that is what I pointed out.

There are enough proven setups out there right now, that you can pretty much assure yourself of getting a good gain with the FAST 90/90. In the last year, though, we have seen a plethora of new heads and blocks, and maybe rethinking some of the basic combo's could yield some bigger gains with a some money in your pocket. Is that so far fetched?

-Geoff

 

 

You're not saving any $$$ by not getting the Fast. With different valve events/cam this car may have made more power with a 90/90 set-up.

 

We're ALL cheap bastards!

 

sounds about right

 

We're running a 244/248 112+0 LSK lobed cam on a 347 (built by Erik) with a FAST 90/GM90 which makes power to about 7300-7400. The car has gone some 10.80's at 128 MPH in +1800 or worse DA witha bad launch (1.5 60'). I expect if we can get it out to the track in decent weather with a good DA we expect to be looking at 10.40's at 130-131 MPH.

All I've seen from a FAST is an increase in power. This is both on ported LS6 heads, and also on the AFR heads.

JakeFusion, I'm interested to hear your reasoning behind the restriction in HP and Tq, and also your logic on the valve events. You seem to have some well thought ideas, and I'd like to hear your reasoning behind those statements.

 

Isn't this pretty much true of the LS6 intake as well?

 

Post a picture of said "road racing car" Im curious to see what it is.

 

weve had multiple FAST intake cars peak past 6300 rpm, and carry well beyond that, even with 400 inch motors. Restriction at 7500 yes a FAST is, but by no means worse than a LS6 intake... wheres the drooling tarded smiley when you need it?

 

I think what JakeFusion was trying to say is that the cross-sectional area and tuned runner length of the FAST 90 has ideal harmonic resonance for peak torque at 4800 and peak power at 6300. This is the "sweet spot" for which the manifold was designed. By closing the intake valve later and later, you are moving the power and torque peaks above the "sweet spot" of the FAST. Sure you can make it peak higher than 6300, but in a perfect world, a motor that was designed for a 7000 rpm peak would typically have a larger runner cross-section and a shorter runner length compared to the FAST. Like most things with the internal combustion engine, it's all about compromises and minimizing losses in average power. For that, the FAST is well designed.

 

I had to take a few days from the this thread it was really begining to grate my nerves. Back on topic

IVO is CRITICAL IN A TUNNED RUNNER APPLICATION PERIOD !!!!!!!!!! In fact its the first place to start. If you don't start there you cannot will not get the Wave action in the intake runner to fill the cylinder. IVC would be next. First you must open the valve at the right time and then close it early/late enough to fill the cylinder while preventing excessive reversion.agian critical in a tunned runner because you can set off a chain of timming events that will totally unravel everything you have attempted to accomplish by basically setting off an uncontrolled echo chamber.

EVO will need to be played with and sevral factors are critical to this working. One is exhuast. design the Camshaft for the applciation. If you have a full exhuast system. EVO/EVC is going to depend on lobe length and overlap but in a full exhuast application Overlap should be kept within reason. where that is depends on CI,Header Primary,Collector,system.

these would be the most basic of thing needed to even begin designing a camshaft.

To top this off i have spent some time examing a few Fast 78 and 90mm intakes and there is a disturbing shaping change in the runner.

http://www.popularhotrodding.com/tec.../photo_09.html

Big no no. You never neck down a runner after you expand in and out of a trasition. It can create wave action and airflow choke points. This would be my geuss as to why power fell off. You would never see this in a sinlge plane intake or a dual plane or an ITB or any other intake.If you did i would bet many competing intakes without this design feature would easily out perform but maybe not outflow it.

Have a look at a factory ls6 or ls2 intake. they do not have this runner feature. This is bad design plain and simple. In fact run this design by the guys at reher morrison and see what they say about the runner shape they spend alot of time designing runner or even run it by Hogan. When you create a runner cross section change that reduces then increases volume you have 3 changes in air velocity. Will create problems with wave action and airflow when the engine is working dynamically. It also explains the dip in the power curve.

to adress that dyno sheet. you wouldn't make 360Hp 330Tq on our machine.

 

Yeah. I didn't mean it actually restricts, though it will choke out the power if you fight it.

 

With the proper VEs, you can take power out to 7500 with a FAST. It flatlines however around 6500-6600, but the drop off below 5500 is pretty pronounced. For a street car, I'd recommend optimizing for the 6300/4800 spot to get the most area under the curve - but in doing so, power should carry to 6900-7000, making them very fast street cars. Exhaust plays a role as well, and I love the LG Pros 32" primaries as they really help power under the curve without killing it at 7000 on a 346.

For me, this knowledge came by actually trying a few cams and degreeing them and then dynoing to see where the hell the power shifted to and by studying the plethora of camshafts on here to see how different heads affected off-the-shelf cams. Not scientific, but I know Patrick G has seen similar results. I like 46-48 IVC for a 346 and 50-52 for a 408. 54-56 IVC for a 427 also seems to work best with the FAST for optimal peak without killing the torque - less makes more torque and shifts the curves left of the 6300/4800 line.

I've never seen torque peak above 5500, so to me, there is a definite limit to what the FAST will allow it seems.

Basically, I like the IVO and EVC to be the same and the IVC and EVO to be just a few degrees apart depending on the intake to exhaust flow ratio, while hitting the IVC on the "sweet spot" areas above. For me, that seems to make the best "overall power." I am of course speaking about .050".

As an example for a 427 with convential 15 degree heads that like a 4-6 degree split because of very good intake/exhaust flow ratio with a FAST 90 bolted on, a 244/248 113+1 would seem to be best for the most overall power for a street car. And I do think of the FAST 90 as a street manifold, not a race manifold.

The cam's specs:

ID 244
ED 248
LSA 113
ICL 112
IVO 10
IVC 54
EVO 58
EVC 10
ECL 114
Overlap 20

If the heads were AFR 225s, one could probably see something as high as 575/535 out of a the cam if it were on an XE-R lobe, had a very tight quench, and had a SCR of 12.5:1 compression. The DCR would be excellent at 8.73:1 making this a killer camshaft that could run on 93 pump gas. Of course, I'd love to see a 32" 1-7/8" header to mate to it, but alas.

Will those numbers happen? I don't know, but with that much compression and the proper VEs that seem to work with the FAST 90's design, I think it's within the realm of possibility. Will it carry out to 6900? Probably not since the 427 is so big, but if it carries it to 6700 in something making that much power, it will definitely be a lot to handle for the car lined up next to it.

 

Good detective work. Your getting closer. If you make power over 6200rpm i will go into shock. Make sure to use a dyno that has load absorbers. Dynojet drums often don't decelerate enough or have enough inertia resistance to actually chart power past peak tq.Iw oudl emplore you to bring an Ls2 intake to your test session. They are making awesome power on larger engines. But the secret suace is in the camshaft.

 

I love all the theory getting dispensed in this thread....

But I'm going to stick to my guns based on my respect for Keith Wilson and the reputation he has built and earned and oh yeah....every FAST intake dyno test I have been involved with personally and every individual or shop I have helped out (and recieved independent validation and feedback from) has had anywhere from good to stellar results. I ask you....how could that be if this intake doesn't work effectively??? Note these are on combinations ranging from stock internal build-ups to strokers with deep breathing heads and everything in the middle.

Here are some real world engine dyno results from testing I did over a year ago with my 383....no rocket science or tricks....just a well thought out optimized combination with good heads and one of my ported FAST 90's.

Note how flat and smooth both the TQ and HP curve is on this run....if the engine had slightly larger headers the upper portion of this gragh would have looked even stronger....as it was there was very little sign of it signing off at high RPM (only down 14 HP from its peak at 7200 RPM's). This test was conducted with a basic bones 1.75 LS1 dyno header....a steped header or a straight 1.875 would have increased peak power and carried even stronger past peak. Also note this was NOT a big cam (a 242/248 solid which effectively acts like a hyd. roller some 6-8 degrees smaller) and the engine still managed to cleanly pull the RPM's it did. A more aggressive stick would have looked even sweeter (but compromised the broad focused package I was trying to develop).

Seems to me the FAST intake did it's job admirably here....I mean seriously....could a power curve look much better than this???



IMO, an LS2 intake wouldn't have had a fighting chance here and the next time I do some testing I may just have to bring one....if any of you would like to loan me a ported version I will be dyno'ing a 403 I'm building just after the New Year that should make very similar power (600 ish) so it would be a good test to do some comparisons with. Count on me having a stock one there at the very least.

Have a good weekend everyone...

Tony

EDIT....I'm not suggesting this is the "end all be all" intake for a serious race piece (although properly modified would still work very well on small to moderate displacement applications). What I'm saying is it is a very effective intake on most street/strip applications and also has the benefit of being light and not very condusive to heat (versus an aluminum fabricated intake). For most guys reading this board it is the intake of choice assuming you are still running a cathedral style cylinder head obviously.

 

Interesting how the TQ curve with the FAST in terms of RPM is the same RPM range as the ls6. The ls2 intake would move that power band on a 383 up about another 200rpm or so.

 

Sean,

Quite obviously that is your opinion and for the record an LS6 intake would NEVER carry the TQ and HP on that displacement with a small cam the way the FAST piece did....NO WAY (my opinion).

My guess is the LS2 intake (at least a stock version) would have lopped 30 or so HP right off the top just like the last test I conducted on the dyno when evaluating a 364 CID engine (bonestock 6.0 ltr) with a 230 Comp cam (wide LSA btw) and a pair of our 205 heads.

A stock FAST 90 was worth 20+ and 15 ft/lbs of TQ....my ported unit was worth 33 HP and approaching 25 ft/lbs (I was floored at the time)....no other changes....same TB, tested within the 30 minutes or so it took us to swap intakes and install the same injectors (those are good gains for a decent head swap!). Note these are actual results (not opinions), but if I may share another, my guess is if we had a stock LS6/78 mm TB set-up on this engine the delta between the two results would have actually been less.

As I mentioned in my previous post I will test another LS2 intake (versus a FAST) in the beginning to middle of January on a different combination and will share the results when I do. I'm reasonably confident they will be similar to what I witnessed a few months ago testing the 6.0 ltr engine.

I only wish it were sooner....

Tony M.

PS....One of the AFR Sales Techs actually took a call from a customer this week concerning whether to remove his FAST intake or not (for more power)....more than likely he is a noob probably doing some reading on LS1 Tech but it really hit home for me. Hearing about that is one of the reasons Im still hanging around this thread, not to mention Ive had my hands in a few FAST intake swaps obviously and all that data I have gathered is obviously relevant to this discussion.