View Full Version : Porting a FAST 102 LS3 and ran into this????


4U2NV-SS
07-29-2010, 09:19 AM
So I port matched the lower shell to my PRC heads and then I put the runners inside and notice this.....(see picture)....see the bottom of the runner. What are you porters doing? just porting it as thin as possible? Any suggestions help.

Thanks a bunch!!!!

4U2NV-SS
07-30-2010, 09:31 AM
TTT.... no one esle seeing this with their set up???

Engine_HP
07-30-2010, 09:38 AM
It got fucked.

4U2NV-SS
07-30-2010, 10:58 AM
That is how it came from FAST. It was not noticable until I ported the lower shell.

03EBZ06
07-31-2010, 12:21 AM
that looks like a vacuum leak and tuning nightmare. I was thinking about upgrading. Your post has officially ended that plan. What does FAST say about it?

thedak
07-31-2010, 09:05 AM
You hogged out the lower way too much.

Nice way to waste $800.

ISMELLRICE
07-31-2010, 09:15 AM
whoa :/

Tony Mamo @ AFR
07-31-2010, 10:52 AM
You hogged out the lower way too much.

Nice way to waste $800.

I agree.....you removed to much material from the base.

Try using the slow setting JB weld and build it back a bit towards the runner flange side of the base unit (the area you over ported)

The O-ring that seals the port should still completely seal around the receiver section of the base it fits into (as long as you don't destroy the runner integrity making it super thin) and your intake will technically still function OK when you put it back together.

Its OK for the manifold to be slightly smaller than the intake port opening.....thats a preferred situation versus the opposite effect.

Good luck and be a little more conservative on the other holes assuming its not too late.

-Tony

SweetS10V8
07-31-2010, 11:15 AM
You hogged out the lower way too much.

Nice way to waste $800. You can buy a new lower shell and start over without buying an entire new intake.

that looks like a vacuum leak and tuning nightmare. I was thinking about upgrading. Your post has officially ended that plan. What does FAST say about it?Why, because a non professional over ported an intake and screwed it up? That's not FASTs fault, he should have left it alone or sent it to a professional like Tony, not hack it up with a dremel. (I did the same thing to a set of AFR 195 when I was a teenager, started to port out the CNC lines and the bit caught and cut a hole through the wall of the intake port :bomb: Lesson learned!!)

I agree.....you removed to much material from the base.

Its OK for the manifold to be slightly smaller than the intake port opening.....that's a preferred situation versus the opposite effect.

Good luck and be a little more conservative on the other holes assuming its not too late.I agree too aggressive on the porting, and if you look at an unported FAST it does exactly what Tony is talking about with the overhang. FAST told me at PRI that they design the manifold so that the runner is slightly in, because that's OK, but the opposite is never good. And that if you really wanted to sand roll them even you can.

More conservative is always good advice, I didnt touch my LS3 102mm LSXR, not even with a sand roll! No issues!

Edit: I remember reading about this in the instructions;

http://inlinethumb58.webshots.com/47161/2467940820060344825S600x600Q85.jpg (http://rides.webshots.com/photo/2467940820060344825DQpQwP)

thedak
07-31-2010, 02:16 PM
You can buy a new lower shell and start over without buying an entire new intake.

I remember reading about this in the instructions;

http://inlinethumb58.webshots.com/47161/2467940820060344825S600x600Q85.jpg (http://rides.webshots.com/photo/2467940820060344825DQpQwP)


Wait till he sees how much just the lower is by itself...

$260

bayer-z28
07-31-2010, 02:26 PM
At least you don't have to replace the ENTIRE intake. Good feature of like the modular design.. :)

4U2NV-SS
08-01-2010, 09:41 AM
Once I tightened down the runner it fits much better A little porting on the runner and it should be match pretty good. My main concern was the splits of the runners at the bottom. I have not call FAST yet I will tomorrow.

69LT1Bird
08-01-2010, 10:05 AM
What are you putting the intake on? Just curious.

SweetS10V8
08-01-2010, 11:04 AM
Once I tightened down the runner it fits much better A little porting on the runner and it should be match pretty good. My main concern was the splits of the runners at the bottom. I have not call FAST yet I will tomorrow.The split of the runners is from how they are made. Just by taking it out and looking at it you can see that its a two piece design that is most likely glued together or vibration welded.

If your going this deep into porting you obviously need to start working with some epoxy which makes the split in the runner a non issue. Remember once you start porting the runners, you may screw that up and have to buy new runners and a base!!!! Your porting beyond FAST's intentions and therefore have to work around any issue you may encounter yourself. That's hot rodding in a nutshell.

If you plan on continuing, I would scribe around the runner so you can see how far you have to open up the runner to match the base and figure out when to start tapering it back into the original runner. There are many things your are changing that affect how this runner will react now. It was designed with a certain amount of taper and your changing all of that, and probably not for the better.

I have Lingenfelter CNC heads and my base lines up perfectly with no porting at all. Plus I think all this porting could cause you issues because when you bolt it all back down as an assembly every single port wall isn't going to line up exactly. Your most likely going to have some of the cylinder head on the inside of the runner creating a wall or a very large disturbance in the airflow path to the valve.

4U2NV-SS
08-02-2010, 09:06 AM
Yeah I thought about scribing it and porting it close to that. I will also seal the split. Is that JB weld stuff pretty good?
Now that the runners are bolted down it all looks like it will blend together well.
I marked the intake and heads in 2 spots were I can line it back upin the same spot.