A word about our stock intake

[HOTSIX]

Well guys...since i've got my turbo off 'cause it's mangled and getting fixed...I decided to pull the intake and heads off too.

I'm probably gonna end up porting them myself with my die grinder 'cause that obviously seems to be the cheapest route.

I was looking at the intake when I got it off and was shocked how much casting marks, rough edges, excess material there is etc. Its tight. My index finger almost got stuck in cyl #4 when I stuck it in the runner !!!

There is so much room to play with there as far as grinding off goes.... I couldn't believe how restrictive that area is when I put the gasket up to it..

The only distance you need to port on the intake is about 4 - 5" in from the heads. There is a large "tunnel" inside the intake....I was of the impression that it was small all the way from the injectors right to the turbo inlet. Thats not the case.

The intake only seems to have restrictions at the turbo inlet (where EGR hump is) and then it opens up to the "tunnel" area - with the runners branching off inside at 90 degrees - then they get real small where they mate up to the heads.

There's a ton of room inside there.... never realized that before - so for anyone who is considering doing there own intake - it's not looking to be as bad as I thought it would be.

I'll post pics of the job...step by step as I go !

 

[bwallace]

I would love to see some pic's, I am thinking about porting them myself also.

 

[FJM568]

If I'm not mistaken, I think Lee Thompson has experimented with all different configurations of ported stock intakes and came to the conclusion that you really don't need to cut one open to see big gains...Just port the turbo inlet some and clean up the ports and make them bigger but don't open them all the way out the what the stock intake gasket hole size is and absolutely DO NOT make the intake manifold ports bigger than the intake ports on the heads...It's better to leave the intake manifold ports slightly smaller than the ones in the heads...

Good luck and let us know the results...

 

[turbo6x2]

This is correct. Lee said that this step really wasn't necessary, especially if you plan to run alcohol on the car.

 

[6SENSE]

The more I see of these posts about porting the stock intake, and how you dont have to do too much to it, makes me think more and more about the V1 Ive got on my car . After what Ive heard over the last couple of years since buying it, I wonder if I would be running better if I took one of these stockers Ive got laying around and put it on instead!

 

[HOTSIX]

FJM568, Turbo6x2

So what you guys are saying is that I should port the intake runners large - but NOT to the size of the gaskets ?

I'm not sure why you said that...keeping in mind here that this is my first port job.... wouldn't it help flow - can you explain to me ?

Secondly, why is it better to have the head ports larger than the intake ports...? Won't that cause air turbulence prior to it entering the comp. chamber ? I thought port matching / gasket matching was what I was supposed to do...? Does this have something to do with this being a turbo application ?
I will be taking the heads off and porting them as well....so all of this info is great from you guys !

 

[6SENSE]

Im thinking the reason is to not create a funnel effect. The ports should get larger with the flow not smaller (as with exhaust).
Right?

 

[WH1 85]

This is a great thread, I just got me an extra stock intake. I am going to port it, and I did not want to experiment with my original. Got a set of heads as well. Any pics of someone going through this process would be great. Or if anyone has detailed pics of an intake that they have ported, ( And had good results with), that would be great as well. Measurements of just how large the ports should be blown out to as well as the turbo inlet.

Also if anyone has pics of the insde of the intake, that would be good also. I'm curious exactly how it is set up. But I'd prefer to not have to cut mine open.

 

[FJM568]

If you make the ports in the intake larger than the ones in the head, you will have a "step" going into the head, which will disrupt flow...Not good...If the intake ports are a little smaller in the intake manifold and a little bigger in the heads, then air will flow better with less disruption in the airflow direction...

As for porting the stock intake manifold out to the size of the gaskets...I think that I had heard somewhere that the runners on the intake had to be welded up so that they could port the runners out the same in all six...If you try to port them out to the size of the hole in the gasket, you will break through the wall, but I'm not sure where(maybe to the outside or something)...That is just something that I have heard over the last couple of years from some who have tried to port their intakes out...Someone who has done this may want to jump in a correct me if I'm wrong...

As I've said, I haven't done it, but if someone with more firsthand knowledge of this would jump in and correct me, I sure would like to know the right info as well...

 

[WFO]

Originally posted by FJM568

As for porting the stock intake manifold out to the size of the gaskets...I think that I had heard somewhere that the runners on the intake had to be welded up so that they could port the runners out the same in all six...

i think we heard that from louie...a few years ago when he had his intake cut apart and ported.whoever he had doing his intake had to "weld up" the ports to match them to the gasket.i haven't heard anything since on this subject...you would think that if lee thompson ported his enough to run 10's and alan(6packtogo) is max porting them we would hear something about being careful with the ports.

later,sean

 

[cool 84]

I'm the one that had the welding done. Mine is to the Felpro 1200 gaskets all the way up. I broke through in about 5 different spots but mostly because I made all the runners straight, more like the 86-87 intakes. I also made it into a big open chamber by removing the zip tubes and dividing wall and took out the egr floor. My heads are tapered so they match to the intake and the taper down to the regular port size. I would rather have the intake outflow the heads anyday than the other way around. It wouldn't do much for velocity. I think it worked because my car ran very hard for such low boost, timing, and all the problems it was having for the mods done at the time. The top end was really noticable with the porting.

 

[HOTSIX]

Alright...so then a general rule to follow is that if self-porting - be careful not to hit the walls of the runners too deep.

After reading this thread I looked at my intake holding it up on it's edge with the gasket on it so I could see the outside and the inside....it sure looks like theres a whole lot of porting to be done. Also, my Fel-pro gaskets are not wide enough (if properly marked before porting) to cut through the walls of the runners on any cyl. if I port the runners to the size of the gaskets.

Has everyone looked at the pics on the iwinengineering.com website under intake porting? There 3 great close up's to show what they have done. I plan to copy that port job.

Problem - how the heck do you get at the EGR bump area - or the area where the turbo neck feeds into the intake ?

There is so much material to remove in there but its not flat...its like a peak...not sure if I might be better to bring it to a shop for that part only.

It looks too hard to get at with just an air grinder stone.

 

[FJM568]

Someone has posted something before about having a piece of aluminum angle heli-arc'd or tig'd on top of that egr bump area there at the turbo inlet so that the airflow diverts more smoothly...

 

[cool 84]

Just remove the EGR passage completely. It's not going to be any worse than the factory setup.