I ask myself... why did GM ever design these TPI manifolds so that they have hardly ANY material around the ports for the intake gasket?

I want to port-match the TPI manifold to ordinary TPI intake gaskets, but there is not nearly enough material around the injector hole to do so. If the gasket slips a single millimeter, there will be a leak there. Even if you could line it up PERFECTLY (and you never can), the amount of manifold that actually touches the raised lip on the gasket is pitiful. It's bound to fail. We're talking regular, OEM-sized gaskets, too... I couldn't imagine porting out to a 1205 or something, like some people do.

Is there anything that I can do? I'm even leery about installing it back without porting, simply because there's still hardly any material for the gasket. What about getting the corners welded up to provide more sealing area? Is there a liquid sealer that I can use, that won't squish into the ports?

 

What’s the brand and part number? Looks like they gave you the “wrong” gasket. I say that because it appears to be about the size of a FelPro 1206. I’ve used 1205s to port a number of TPI intakes with NO problems.

Is that a Mr Gasket intake gasket? If it’s a Mr. Gasket,,, I don’t use them,,, tried a few times back in the 80s,,, but they always had some kind of alignment issues – usually had to slot the holes (up, down, right, or left) to locate the gasket properly. I’ve had a few FelPro gaskets slightly off,,, but nothing like what I saw with EVERY Mr. Gasket I used.

 

The type that's in the picture is a Mr. Gasket Ultra-Seal gasket labeled specifically for GM TPI intake manifolds. The center holes do need elongated, and I need to cut an EGR passage.

I also have a set of generic Victor gaskets that align exactly the same way, and have the same port sizes.

I think that I'm just going to make my own gasket... Jeg's and Summit have sheets of the gasket material available, and I think that might be the only sure-fire way to guarantee a proper seal.

 

Is the Ultra Seal you have a 5820?

 

Nope, 5851. Jeg's lists it as "305/350 (86-92) w/TPI Stock Ports".

If I recall, I was going to use the 5820s, until I measured the ports -- they were nowhere near the right size.

 

I've ported a number of TPI intakes,,, I can tell you if you buy a set of FelPro 1205s,,,, all you'll have to do is trim the gasket material up to the embossed bead to clear the injector bump - unless you have a good bit of core shift on the other set of ports (those in the picture look fine).

However, unless your heads are opened up to a 1205 gasket opening, I wouldn't touch the intake exit. If you port the exit larger than the entry of the heads, you'll cause more reduction in flow with the turbulence caused by the intake opening being larger than the heads than if you had left it alone.

Take or leave the advise,,, but I'd work the entry lip / roll at the runners on the intake and the passages leading up to the exits,,, but leave the exit size stock if the heads are stock - still use the 1205 gasket though.

Good luck

 

Thanks for the tips, BadSS. I was considering leaving the ports alone, but the motor isn't really stock anymore. The TPI plenum is ported, I have a ZZ4 cam, headers, and I'll be custom tuning the EPROM chip. Plus, I've fully ported a set of L98 heads for the engine. I think the extra port size gained in the intake should match up well to the rest of the mods, and at the very least lessening the restriction that factory TPI already is.

Good advice on the runner openings, too... the port reduction (lip) appears to be quite significant.

 

With the way the factory put the injector bung in the runner, whats the point of gasket matching it ?

-- Joe

 

I believe that this picture belongs to ede. In a post about porting the TPI manifold, he said that he hasn't had any problems with this method.

 

Ede shoulda taken a picture with the injector IN the runner, then you'd see what I mean.

-- Joe

 

anesthes, are you talking about the location that the fuel is sprayed into the intake tract? I stuck an injector in my manifold to see what you meant, but don't understand. Are you referring to enlarging the side of the port where only the injector resides, or the port as a whole?

I realigned my gasket and if I were to match the manifold to the gasket, I'd be cutting more into the wall opposite the injector -- from what I gather, cutting into this floor area isn't nearly as advantageous as the roof area.

 

FelPro is the only gasket in my vocabulary. Always the right gasket for the job.

 

The problem with any MPFI manifold and TPI being worst, is the injector is right there at the roof. You can't port much without ruining the injector seal, and when your done, you havn't bought much anyway cuz the injector is in the way of the airflow.

Kinda the trade off.

-- Joe

 

That is my picture. I have no sealing issues. The actual seat where the o-ring is, thats quite a distance from the port roof... and if you run something other than the bosch with the cone, like a pintle+cap style injector the protrusion isnt enough to worry about, its kinda like having a valve stem in the middle of the pathway.

 

Without getting too much into port matching, wouldn't having a smooth transition through the tract help, regardless if the injector is in the way? anesthes, I agree with your logic in the roof area, but what about the other three walls? After realigning my gasket, I can cut into the floor area and hardly even touch the injector bung... which still opens the port as a whole, and prevents the air from "expanding" (does it?) when it reaches the head, which would have a larger overall port. I would think that reducing this "step" in the port would help somewhat.

I need to get a book on fluid dynamics .

madmax, I do apologize about the picture credit... there's so many images that I have saved that I don't remember who they belong to.

 

Of course it would be better, for flow in an engine that isnt running and just has air going through it. Take a look at the Accel and First bases, see what they do around the injector area. Its not much different than the area around the valve guide. However, its still a relatively small protrusion. Personally, I'd be more worried about the cross sectional area in the middle of the base.