I've been doing a lot of searching and have a couple questions. How far should I go into the runner side of the intake? I've seen some do 1 1/2 and some go as far as 5 inches? I've read mad maxs aritcle a million times and I still can't figure out what to do.

On the runner side can I open the port up to 1 3/4? How close am I going to be before I go thorough?

Should I siamese the stock runners? If I do will I need to siamese my plenum?

I've already started on the intake, I'm currently at 1 1/2, just wanted some encourgement before I go any further.


350 bored .30 over, ported plenum, lt1 injectors, headers, kn filter, ported 882 heads, stock maf(scared to touch it)

 

There is no right or wrong answer as to how far in to go. Just have fun with it and do what you think is right, thats what everybody else is doing, and so far they're all happy with the results. I'm gonna go about halfway through mine, more or less depending on intoxication vs. patience level during the grinding.

You can't siamese stock runners (well you can but if you had the skill to fabricate this feat you wouldn't ask such a question)

Don't go too nuts opening the base runners up. Thats stuff is way thin. If you don't have the capability/tools to measure constantly as you go, then don't try to do anything but smooth it over. Seriously, there isn't anything to the runner passages.

Don't forget to reshape the intake exit at the head. From the factory everything about it is wrong. Concentrate on making it a smooth transition. Luckily the injector boss gives you some extra meat to raise the roof here to fix the angle.

 

here ya go

maybe this site can give yo usoem basics as to how to port your intake

and as for how far you go it all is what kind of setup are you wanting to run


this should help explain though

http://grapeaperacing.com/GrapeApeRa...ntaketuned.cfm

 

well i went in 4 inches when i did mine.
my reasoning is that i want it to act more like a lt1/miniram intake but look like a TPI intake. by going in further you make your runner length shorter and create a bigger 2nd plenum area.
you should go no less than 3 inches i think. espically since you have a 350 and can benifit from the mod.
and then later on if you want to put a bigger cam in you can go further and get even more benifits.
when i get my 350 and get a bigger cam i'm going to siamese it all the way down to a half inch to 1 inch behind the fuel injectors to make use of more top end of the cam.
what you have to realize is that you will hurt your low end torque a little but greatly benifit from top end power.
it will take time so just be paitent. try to get some bits that have long shanks and get some bits made for aluminum. just go slow on the first one and leave room for error. you can always go back and take more out but you can't put it back very easily
my times in the sig are from when i only went 1.5 inches and it did help a little bit.
as for the runners. i feel that the stock ones are going to work fine. what you do by creating that second plenum when siamesing it more than 2 inches is allow each cylinder to pull from 2 runners making the small runner problem non existant (spelling?)
have fun and just post a question or email me if you have any
good luck
Andrew

p.s. if you have your engine down that far it really wouldn't be too hard to get the heads off and give them a port match job or even take them somewhere and get some good porting done. you can do it yourself and get good results if you take it easy and make each port like the other one.

 

Well thats what I'm going to do then, have fun with it. I figure I'll go four inches or so and see what it looks like. I'm a little a nervous about hogging it all the way though. I have the motor on the stand right now and just got done using standard abrasives guide to head porting. Was really happy on the heads came out. I have a local machinest as well who gave me some pointers and some heads that had been ported as well for a guide. I should have mentioned that I have a comp cam and comp valve springs. I don't have cam card handy but its around .450 of lift, nothing to crazy but good for now.

Hey ed when i mentioned siamesing the runners, I had seen a post where they had been notched between the two tubes for better flow. I don't think I will mess with those though.

I'm printing out this induction pressure wave article, looks like some good info.

When I get done I'll post some pics.

 

oops forgot to say also take a look at the helmholtz resonator

http://grapeaperacing.com/GrapeApeRa...ehelmholtz.cfm

that will also give you a more in depth look at the intake and how it works