I had originally a Corvette 1999 FRC.
Cartek in NJ tuned it and did the following mods:

Drag Race LS7 clutch
LS7 flywheel
New Slave
Hardened output shaft
4.10 gears
Vara Ram air intake system
Kooks 1 ¾” stainless headers
Kooks stainless intermediate pipes w/high flow cats
Z06 oil pump
Rollmaster chain
ASP pulley
Cometic heavy duty head gaskets
Flowed and matched set of 38# injectors
Port intake to Stage 2 (Cartek)
Comp Cams Type R lifters
Cromoly hardened push rods
Custom Cam stage 3 (Cartek)
Notch pistons
Cartek stage 2 heads full porting…..
FAST 3 piece intake manifold w/78mm throttle opening
Upgrade to Stage 4X Z06 heads
Ported throttle body
... I must have missed some of the tunes but still it works great


Output was 455 RWHP. Not any FI or NOS.

Now the lower intake manifold bottom has a big crack resulting a bad idle and constant P0101C code due to leaking air!!!

I guess it is time to get new intake manifold (complete) and perhaps a Throttle Body and MAF as well.

Who sell packages (intake manifold, TB and MAF) and what would be optimal based on my tune described above?

Maf sensor is 5-pin Z06 version, TP motor is 2-pin and TB sensor is 6-pin connector. Those must be 2001-2004 era things.

Who sells these things???

 

If you get a NEW FAST it will be a 92mm and you will need to get a LS2 90 mm TB with adaptor cables. That will also mean another tune.

You can FIX the past tha you have now.

Bill

 

I have a very similar set up as you. I ported my fast 90 and I have 450 RWHP

Bill

 

I tried JB weld with glass fiber mat. It did last one month and then the repair gave up => what could be the solution?

 

Part of the problem is the plastic is saturated with oil. Yoiu need to degrease it till its spotless and then make the surface ROUGH so the epoxy adhears to it.

I have used a purpose made PLASTIC EPOXY from a company called DEVCON

They have a new epoxy that sounds just like what you need!

http://www.devcon.com/products/produ...%E2%84%A2%20II

If you cant get the formula above try this one:


http://www.walmart.com/ip/15632447?w...l5=pla&veh=sem

If that fails, I would find an actual PLASTIC WELDING Machine and use a plastic welding rod specifically for that type manifold plastic. Call FAST and see if they can tell you how they would fix it.

Hell,, maybe they have a replacement bottom section!

 

Instead of trying to fill and repair the crack, can you get a thin piece of plastic similuar to the manifold plastic and epoxy it on top of the crack?

 

Cheers!
I checked the intake and the crack had has expanded. This means that the fix that I made with JB Weld was OK but still underpressure was too much for weakened intake structure. Probably the cut that is across the intake has too many sq in which equals too big expanded area and force will became too big for any adhesive to keep the parts together. I guess that if I use stronger media like Durmetal from Switzerland I risk to damage valves if something goes wrong and if it cracks and goes in to the combustion... Right now JB Weld just flow throught the cylinders/valves without damaging anything.

About adhesive...
I tried to find Devcon from the local specialist but it was dead end.
It seems to be somnething for industrial purposes says the shopkeeper.

I'm considering to just give up a little bit, purchase a new 92 mm Black FAST and still keep my ported 78mm TB and Z06 MAF. This is the way to avoid new tune but stil keep the door open to future upgrade...
What do you think Bill?

 

The FAST 92 uses a LS2 TB so,,, you cant use a stock C5 TB on it.. That is why I tried to come up with a way to fix yours.

I wouldn't try to fix it from the inside. Try to fish plate a similar material on the underside of the base tray

I still think you would be very successful with getting it plastic welded.

http://www.youtube.com/channel/HCfbhWKRRNvI4

http://www.harborfreight.com/plastic...ure-96464.html

If you install a new FAST 90 or 92,, You will most likely need a new tune to get the best efficiency from the swap.

Bill

 

Did the installer change the valley cover bolts out?
As far as I know, those should have been changed in the first place as the stock bolts can interfere and in turn crack the manifold.

Might want to look into what caused the crack also!

 

They come up 4.5mm.

 

You must use these:







FAST includes them with manifold purchase.

 

check out a company called McMaster Carr
search under epoxy, look at the loctite two part cartridge it bonds ABS, nylon, polycarbonate, and PVC.
I would use a thin sheet across the outside of the crack to bond/seal.

 

more info
The technological process of adhesive bonding of polymeric materials involves the preparation of the surfaces to be bonded (roughing, shotblasting and sandblasting, etching, electric discharge action, and degreasing with organic solvents) and the application of the adhesive by methods similar to those used in applying paint and varnish coatings. The adhesive layer is then allowed to stand until the solvent is removed. Next, the surfaces to be joined are placed in contact and allowed to stand, sometimes with the application of heat and pressure. The quality of the adhesive seam can be determined by subjecting the bond to shearing stress or by using ultrasonic techniques.

 

Uhhhh this stuff is going to be too advanced for me.

I think it would be more safe for the engine if I install 92mm FAST with 92 to 78mm adapter plate. This way I probably skip the tune but still have option for future easy upgrade and have full safety tor the engine. Last thing I want is to have some plastic parts going through the valves due to my bad fix.

What do you think?

 

You will be needing another tune.. No question about that in my mind.. Is $300 of insurance is worth more than a chance of running leaning and ruining a motor to me. That 92 will change the airflow significantly from a 78.. Regardless of tb size

 

You have a good point. I have no informaton how far away 78 ported FAST is from 92m non-ported FAST.

 

I know an older thread but instead of trying to epoxy...what about a plastic welder? I have done this to my Hobie Kayaks before. One can be picked up from Harbor Freight pretty cheap. SO why not simply fill the crack, after degrease, with more plastic material and join it all together?