Ok, I removed the plenum today (probably the first time since it was new), and I noticed a thick layer of greasy black GUK for lack of a better term. What is this? The car's got about 150k and she runs great. It's in the plenum and runners, and I'm sure it goes beyond, down into the manifold. What should I do?

 

It is just the normal build-up of carbon, if you have a parts washer you can clean it out, but it will come back. Remember the EGR is reintroducing exhaust right after the throttle body. You can also try to clean it with brake cleaner.

Nick

 

Abubaca,

Put it all back together and forget about it. Unless the buildup is more than ¼" thick, it isn't affecting a thing.

 

You can try using a throttle body and intake cleaner by Gumout... i used it not to long ago to clean out the same problem. just do what the bottle says and it should clean it out a little...

 

You know what you need to do? You need to throw that stupid car away. Oh wait since it is a piece just sell it to me for like $10 or something.

Like stated above dont worry about it just port the crap out of it and leave it at that.

Evan

 

-Vader-

What are you smoking???

Hmmm, maybe it would affect horsepower, isn't that what we all want more of? It is a known fact that even a stock 350 is limited by the TPI's manifold size. Our TPI engines are now all at least 10 years old, and I can imagine that the carbon is starting to build up and is limiting our engines potential even more. Many people on this board spend just shy of a thousand dollars on high flow intake manifold components to get a few more vital tenths of inches in runner diameter to help their engine breath efficiently. Thanks to the fact that I am a full time college student I can't just go out and buy one of these manifolds. Instead, this spring I am planning on cleaning out my carbon build up and port matching my TPI for an, almost free, increase in flow. I know for a fact that I do not have 1/4" of build up but I feel that any flow improvement is worthwhile if you do it to where your engines flow is hindered the most.

Do me a favor Vader, and don't take this post the wrong way. I have read many of your posts on this board and in my eyes you are one of the most knowledgeable members of this site, and for the most part, I take your opinion as fact. :hail: However, I will have to disagree with you on this topic. JMHO

 

For one, how is Vader supposed to take that? That was an insult with an out at the end. Anyhow, I would back up my information before I just spit out unsupported conclusions.

 

When I had my upper/lower intakes off, I took them to the local machine shop so they could bead blast them. Then I did some porting. I can't remember for sure how much, but I believe it was less than $40.00 for the bead blast.

 

-gofaster-

I wasn't trying to insult anyone, I just thought it was out of character for vader to post something like that. I also don't know what type of support your looking for that I haven't already provided but I will try and clarify. I see from just looking at your sig that you agree with me. You have an accel manifold on your firebird, and chances are you put this on to increase your peak horse power by extending your availible rpm range, right? This works based on the fact that increasing a ports cross sectional area increases it's maximum possible cfm (flow rate). This increased flow rate will help fill the combustion chamber more efficently at high engine speeds, which will in turn raise the peak horse power along with rpm range for your engine. This is the weak point of our manifolds. They are designed to promote low to mid range torque at the expense of high end horse power by way of 'tuned' runners. Well, further decreasing your runner volume, by carbon build-up or any other way, will increase this effect and give you more of what you don't need, low end torque at the cost of your effective rpm range; which is a good way to make our cars slower. I feel you want some numbers here instead of theory. Well a dual catalist equiped stock TPI 305 makes 230hp stock (0.75 hp/ci) and a similar 350 will make only 15 hp more (0.70 hp/ci). Our 350's in stock form have big flow limitations, you have to admit that, so increasing this limitation is somthing you'd want to avoid. In my eyes, loosing 1/4" of your runners radius would increase this limitation dramatically

I am not looking to start any fights here, in my opinion we're all on the same team, GM's team. If vader were to look closer at my earlier post than gofaster did, I think he might find a compliment or two; regardless of the fact that I disagreed with what he posted.

Well, I feel better now.

 

Oh, I agree with that flow limitaion stuff. But again you have no numbers on CFM decrease, or even measurements. You just regurgitate general information. We all think we will notice the flow decrease, but will we? I also agree with you on the fact that Vader's 1/4 inch comment was less than ideal. A quarter inch is a massive protrusion. We are talking .001 of an inch here. Maybe the carbon actually smooths the flow by filling in casting imperfections or maybe it produces more tumble right before combustion chamber entry thus allowing better atomization.

I did read your post and see the so called compliments but IMO you don't ask a thirdgen elder "what are you smoking?" and then say "oh, but you are really smart, usually." They don't cancel.

 

Well, I have to disagree with Vader on this one too. True if you put it back in the way it is you're not gonna lose any HP or anything like that. But if you already have it off, you might as well clean it now. What other better time is there to do it?

I used a tonne of TB cleaner and a wire brush to get off most of the gunk. It's not easy and is time consuming. Then with a bit of Ajax and a cloth I did a final cleaning/wipe down. And followed up with a very good rinse of water to ensure there was no left over cleaning residue. I hope that helps.

 

EVERY LITTLE BIT HELPS.... besides.....why let it build up, if there is some in there clean it becausei will just continue to build after that.

 

Maybe he said that, because with in a small amount of time that same build up will be there. So wasting time and money on cleaning is pointless since the small amount he's speaking of will just build right back up.

Don't know... just a guess. I'm curious on this one too.

 

If you pull something off clean it the best you can before you put it back on. No matter what it is. The PCV will put it back in but it will take another 150,000 to get back to this point.