little bit of Porting (w/pics)

[Chevman2448]

I looked through my throttle body the other day and noticed that it needed some porting since I have an Acuufab TB with an OEM dog house. There was an edge around the entire TB (didnt take pics of that).



Now that I did that I noticed some things when I had the doghouse off. The lower intake was extensively ported (so were the heads from what I can see into the intake chambers) Maybe a bit on the severe side. Im no expert so Im not sure if they did go too far. I found 1 hole in each intake tube that are filled with what appears to be epoxy. Any info on this? Is my lower intake junk? I have a welder so I could weld it but I would have to buy the specific gun to do it. I tried to get a picture of the porting in the heads but all the pics cam out blurry.

 

[earlbrown]

That intake is pretty ported. Someone spent a lot of time on it. The EGR tower has been milled off and filled and everything smoothed. In real life it probable didn't add much power.

Those holes look like something someone would do if they wanted to hide a nitrous system. If you ever have the manifold off it might not be a bad idea to tap them and saltwater install an aluminum bolt from the bottom then grind them flush.

 

[Chevman2448]

I actually thought about doing that with the holes. Or picking up an aluminum welding gun for my welder. The bolt idea is probably a better and cheaper option. I took it off because I wanted to check the hard vacuum lines for leaks and the Throttle body was in the way of the 10mm bolt that holds them on. I also noticed that there is an RJC racing power plate on there too. Im finding ALL kinds of goodies and work that isnt normally done on builds. Personally I would have saved money for a bit longer and opted for aluminum heads because time is money. I ported 305 chevy heads before for the fun of it and it was not fun.

 

[earlbrown]

That's the cool thing about turbos. You can get along just fine without pouring tons on money into heads and porting and such. Small nuances in flow really don't mean anything in a pressurized application. I usually recommend leaving the heads in place unless you just have to pull them for a reason. The gaskets, oil, coolant, studs alone are expensive for very little to 0 return. Now to mention the 100's of occasions where someone breaks a head seal and plays hell keeping gaskets in the car after that.


The reason I said bolts from the bottom side is because you don't have to fool with the welder. I've ready tales from the past where people were trying to weld on that casting and making a mess. Then having to take it to a cracker jack welder and they have a hard time with it. The last thing I'd want to do is screw up a casting or warp it when 5 minutes with a tap will get you back safe.

 

[Chevman2448]

Thanks for thin info. Its appreciated. I wanted to check for vacuum leaks since my Boost gauge doesnt seem to want to work. Though I did disconnect the line from it and the gauge is getting vacuum at idle. Sounds like the gauge is bad to me.

I dont intend on taking the heads off unless the gaskets were not sealing anymore. I dont like to take things apart unless there is a reason to. The head bolts are of the ARP variety they just arent studs. You are right on the welding. There will likely be slag left over that I would have to grind off. I would do the bolt trick for sure. I am seeing raw fuel in the PCV line though, so pulling the lower intake off might be some thing I have to do.

 

[earlbrown]

If you put aluminum bolts int here coated with salt water, they'll be a permanent fix in a very short time frame. You'd twist the heads off trying to remove them!

 

[Chevman2448]

I got it all back together and it runs pretty good. I ordered a HD PCV valve from Kirbans that will be here this week. So that should take care of the oil inside my intake. I checked the boost gauge line again. It has full vacuum. So I disconnected the line and even under load the line is still pulling vacuum. From what I read it should be pushing air instead of pulling.
Any Ideas why it is still pulling vacuum instead of blowing air?

 

[earlbrown]

You have a vacuum line that's showing vacuum at full boost?

That's not right (and a GREAT place to introduce water injection if it existed! Better to just let the unicorn do it. LOL)

 

[Raeban]

Are you certain that your boost gauge connection is not downstream of a check valve?

 

[Chevman2448]

There is only one spot that there is a check valve and its connected to the heater vacuum and one other spot. The hose i used was for the charcoal/emissions canister that the last owner removed so I know without a shadow of doubt that there isnt a check valve on it.

 

[Chevman2448]

I believe my gauge is bad. I took the gauge back off and put my vacuum tester on the feed tube. Vacuum is at a constant 25 (or so inch lbs) then when I power brake the car the vacuum goes down to 10 or less. My gauge doesnt go back to zero so I think its 5 inch lbs off its measurement but either way vacuum does go down under load.

 

[earlbrown]

Vacuum should drop under load. The highest reading you should ever see is during engine braking.

 

[Chevman2448]

Well I found the issue. I had a vacuum leak on the distribution block on the throttle body from the middle line. Its hard to hear them when a turbo is whistling away near it. The line had been replaced and it appeared usable, guess not. It started idling smoother when I put zip ties on the lines. I also put in the HD PCV. The new (past owner replaced) pcv OEM replacement was allowing oil to be pulled from the crank case into the throttle body. Explaining the oil in the intake. Only thing is, is the Boost gauge still doesnt work but I can hear the turbo start to spool at a much sooner RPM, so I know the gauge is bad.

 

[Chevman2448]

Got a new gauge and reconnected the vacuum hose to where the map sensor is. Finally got it to move while power braking. So it appeares that the gauge was bad.