[Jasons 69 Chevelle]

Cars running great but I can’t leave it alone 🤣😂. Skipped port matching the intake. During my build. Decided to try to extract more power. Heads are BTR/TEA Trickflow 235’s. Kinda shocked how far off the port is. First couple pictures are stock fast. Red arrows are problem areas. One side does line up really well and will not be touched. Will plastic weld the area at the bottom left of each port and a little up the runner. Don’t want epoxy inside the intake possibly coming loose and destroying the engine. Used a hooked razor blade to mark the bottom side of the fast with the lower shell bolted into place.

3rd and 4th photos are with a little porting

 

[Jasons 69 Chevelle]

Decided to remove and plastic weld the structural ribbing on the bottom of each runner.(leaving the top rib intact) Seems like a good idea to remove the ribs increases plenum volume slightly and increases air flow around each runner.

 

[Jasons 69 Chevelle]

A shot of the unported runner to lower section filament. I have matched the runners to the lower section no photos of that yet. Second shot is the beginning of plastic welding the lower section to
Match the head port. The welding will run up the runner a couple inches so it doesn’t form a aggressive ramp. Everything will be smoothed out once the welding is complete.

 

[427L88]

I'd be curious to see if there is any measurable gain.

 

[Jasons 69 Chevelle]

I'd be curious to see if there is any measurable gain.

Thats why I skipped it during the build. I will know it’s done and that curiosity will not be there. I’m also going to try to catch the 3rd harmonic, RPM range is from 5984 to 6839 with a 14.75 inches runner inlet to valve. I still need to take better measurements but its close to 16.5 inches currently. (5350 to 6114rpm) A stock fast 102 is designed for 6500 rpm’s on a 346ci engine. Mine seems to choke out around 6600 with 398ci.

 

[70SSOBSESSION]

I would epoxy the intake. Changing the shape of the runner will probably hurt more than the mismatch.

 

[Jasons 69 Chevelle]

Measured the total length 17.5 inches valve to bell mouth. Looks like if I could add 1/2 inch I’d hit the 2nd harmonic at 6527.

 

[Jasons 69 Chevelle]

Here’s a shot of the lower corner filled it to match the head port. Still needs a little clean up. Picture of the runners with lower ribs removed.
Runner shape hasn’t changed other then the ledge to match the heads port will be smoothed.

 

[Jasons 69 Chevelle]

This area got filled back with plastic weld to match the intake runner and ported for a smooth transition.

 

[Jasons 69 Chevelle]

Using recovered porting material and a hot plastic melting iron for welding and filling. I don’t trust the available epoxy’s to hold to this plastic. I do have splash zone epoxy but I feel it is too hard if it ever came loose would most likely damage the engine. Imagine rocks on top of the pistons.

 

[cv67]

Done a ton of various plastic intakes over the yrs...so much easier than alum but real easy to screw up too.
Every little bit helps. all adds up

 

[Jasons 69 Chevelle]

Intake is back in will take it out this week if I can get sometime. Initial start up engine air fuel target held very steady set at 14.3 idled in between 14.4-14.2. Engine did seem smoother. Before it would be 13.2-14.8 at idle and hold at cruise perfect. Vacuum gauge has no movement at idle now holds at 12
it would bounce a little 11-13 inches before. Had zero cold stall usually get at least 1.

 

[Jasons 69 Chevelle]

If you look close you can see the old line where the port wasn’t aligned to the head.

 

[Rich-L79]

That is one thing I've never understood about the FAST manifolds. They are plastic, very easy to mold into whatever shape you want. So why were they not molded to be a near perfect match to the ports in the heads? The port locations and sizes are very constant across many types of heads in the same family (cathedral port or rectangular port). They always appear to be off center as well. I've ported stock manifolds as well and they match up better but are an inferior manifold overall (especially the LS2 intake which is what I've worked with).

 

[Jasons 69 Chevelle]

I’ve read the fast 102 does match the 241 heads perfectly or close enough that no porting is needed. Wish Fast would offer closed off lowers sections that could be sent to the head porters for a match.

 

[Rich-L79]

My FAST didn't match well on my LS2/243 heads but the amount to be ported to get them to match wasn't hard to attain. This same FAST will be going on an LS1/241 soon so I'll have to see how they match or don't. I can't imagine that the location and size of the ports on 241 and 243 heads would be any different but maybe they are. We shall see. I wish there was a way to see without taking the FAST apart.

 

[Jasons 69 Chevelle]

Got the car out today for a quick trip. MSD atomic LS tunes itself.
First 2-6 k pull car was lean at 15.5 took about 4 pulls to get it to stay at 14.7 it’s tuned for 13.1 at wot it’ll take a little a few more wot pulls to let the MSD do it’s thing. Cruise afr is set to 14.3 it now holds 14.3 to 14.4. The surging power feel is gone. Car ran great off idle was instant. I’m thinking more air supplied to the engine over the unported fast tune is why I’m seeing lean on the first couple pulls.

 

[300stw]

any updates on this,,,,im loosing sleep over a new intake, something better then my tbss

 

[Jasons 69 Chevelle]

any updates on this,,,,im loosing sleep over a new intake, something better then my tbss

Haven’t taken anything to a dyno tires aren’t roller safe per Mickey Thomson. Car weight is 3700 with me in it and it’s doing a 6.70 on the dragy in the 1/8. Not really set up for drag it’s a PT/street car.
Car runs great, I’d definitely do it again. Maybe just port match and clean up the stock casting. The TBSS is a good intake for the 5.3 not much gain to be had with a fast. If you have a cammed 6.0 or larger the fast is definitely worth it. If your spinning less the 7000 rpm’s