I know much hasn't been discussed on the topic of porting the Fast 90 intake but here's some info to work with. Basically we (me and guitsboy) took the top off of the intake. We then put the lower and middle half (still assembled) onto the heads to check where and how much we needed to remove off the ports to match the intake to the heads. It's noting new but most people know about the bumps in the intake ports that need to be removed but there's plenty of meat to take out of the ports to port match with the heads. We basically matched the ports and then sanded a little farther up into the ports. We didn't go much beyond that but when comparing the design to the LS6 intake it didn't look like going beyond that would really yield much more power. All porting was done with a die grinder and sanding rolls, coarse then fine. The before pictures didn't really come out that well but if you get an unported fast you'll have the before and see the ridges in the ports. We have some after pictures to help show what I described. Feel free to give feedback.
Guitsboy has the pics so he'll have post them.

 

ok, hurry up guits boy

 

Keep in mind this was just a very modest portmatch and cleanup of the casting flash. no major hogging out.

After Pics:
http://picasaweb.google.com/GuitsBoy...AndValveCovers

EDIT: Hotlinking pics didnt work, so heres the link to my album. The first few pics are of My90iroc's FAST intake. The Painted intake is my ported LS6.

 

How did you get the ports to match with the heads still on the car? Did you let the shavings fall into the intake ports? I thought I would pull off the rockers, to close the valves, then port match, and take off the heads to clean, and then re-asemble.

It would be best if I had another set of AFR heads. Tell us your technique. Thanks.

 

LOL!!!

You grind the intake off of the car. You pull the top off and just use the bottom and middle pieces of the three piece manifold. Line it up on the motor and feel for how the ports match up. You'll feel right away where you need to take off a little more meat. Its all trial and error.

 

Do you guys recomend getting the Fast intake ported after I have a set of heads to work with?? And do you think that porting the Fast is a bad idea if I'm going FI later on, as Fast intakes are known to crack at 18 Psi of boost.

 

I used a U shaped pick to scribe the intake. marked it and ported in one shot.

 

guilts boy, did you do a before and after dyno test to see what it got you?

 

sadly no, but he's about 9 or 10 rwhp better than my setup. Theyre very similar cars. Same cam, but he's got better heads, the fast and a 12 bolt. If he still had the 10 bolt, hed probably best me by 15 - 20 or more. And we havnt spent any time tuning on the dyno for it. Just got some quick numbers.

 

All you gotta do is make a template of your head's intake port. We used a pencil and paper to make a rub of it. Then you cut it out and trace it around the intake port in the right spot. Now you know what needs to come off.

 

The porting really doesnt have to be the width of the port on the head. The main thing you need to do is blend back the buldge in the runner and blend in the marrage lines. Word to the wise, dont get gready. The area just inside and behind the intake opening is very thin, it is easier to take out too much and make that area prone to losing its seal. As well, be careful around the injector hole, its easier to pop into the seal there as well.

Brandon

 

Lethl Z06 did a comparison between a stock fast 90/90 and a ported fast 90/90, the casting flash was taken out, runners smoothed out, blending was done on the underside of the middle piece where the air comes around to "enter" the runner. Test was done back to back. There were no gains. This was posted in another thread by him after people were asking for results. Not one person replied after he posted no gains.

I dont think it could hurt to port match and clean up the casting flash, but I do not believe any more porting will result a gain of any kind.

 

I think it will gain, just look how well heads respond to very little cleanup.

However, I do believe intake porting gains are well within teh margin of error for any dyno, especially if the baseline was done with hot oil, and the afterwards dyno was done after the engine had some time to cool down. Ive seen my own engine gain over 10 rwhp just by getting the oil nice and hot before it eventually levels out and then heat soak starts to take a toll.

 

As NSTY WS6 mentioned, I did a back to back to back from a stock LS6 to a stock Fast 90 with NW TB, to a ported Fast 90 with NW TB. It was done on my ZO6 and change time was less than 10 mins (its a stupid easy swap on a C5).

I gained 20rwhp from the stock ls6 to the Fast 90 and gained maybe 1 or 2 rwhp from the stock Fast 90 to the ported Fast. Each stage had multiple pulls and completely tuned spot on to see any varience.

 

Stock heads and a very well designed aftermarket intake are two totally different animals. One has been designed to get the most of the setup and the other has not.

 

When cleaning up a head your improving a "inferior" product, as we see what porting the stock heads pick up. Its insane. However, when you try to improve a set of heads that are say "badass" you dont gain much, if anything. Thats what I think a ported fast is. You cant do enough, to make a difference.

There is a local with a "Mamo" ported fast on a afr headed forged 347. Maybe he would be willing to do some test with that intake, a home ported fast, and maybe a stock one. That would be interesting....

 

I'd like to see that test. The stock fast when placed on my heads had ridges that protruded well into the intake ports of my heads. I'm sure the porting was worth something considering the stock intake port was very noticeably narrower than the heads. Was it worth the 15 rwhp that porters claim? I'm sure it wasn't. I wish I had the time and resources to perform the before and after test as well but I didn't. The bottom line is porting the fast isn't rocket science and it's free hp, even if it's only a few.
If you guys who've done this have any pics it would be interesting to see and compare how each of us did our porting.

 

Granted a fast isnt going to gain as much as stock heads will, especially since its a lower velocity / larger cross sectional area part of the runner. Changing the surface isnt going to have the same affect as changing the valve bowls or trimming the guides where the velocity is high.

However with any product theres always a tradeoff between production costs and gains. For almost a grand, I would have thought the FAST could come a little better finished. IMO there was a good bit of room for improvement. Of course im not saying youre gonna see a huge power increase like you will from heads, but I believe its there.

All I meant by referring to heads was how little you have to change the surface to make a good difference in flow. Granted with the lower velocity of the upper intake runners youre not going to see the same results, but the idea that a little smoothing goes a long way is still there.

Just my opinion though...

 

i would LOVE to see this test, i also beleive its hard to improve somehting that has had so much r&d with just a little blending...but id love to be proven wrong so i can buy something better!

 

I do the tuning for Lethal and the guy with the Mamo Ported fast. As soon as the car with Mamo ported fast gets the new tranny I'll test it with a stock fast and the Mamofied one. I'll be sure to post graphs when the test is complete.