MILT

Hey y'all, I want a little more umph out of my 305 TPI. I have SLP runners and a 52mm TB. Will I gain more by having my stock plenum and base ported, or by getting an aftermarket base alone? I would like to get a fancy base and have the plenum ported, but I can't justify the expense on a mild engine.

I don't have time to learn to port, so I need to have it done professionally. Anyone know an approximate cost?

Thanks

MILT

jd13

Porting a good bit out of your stock base will get you near an aftermarket, but not all the way there. Best route to go imo (not for the money though) is to get an aftermarket base and then port that.

Bort62

You really cannot do much to the Stock Base other than Siamese it... the Material just isnt there.

So if you don't want to Siamese, your only real Option is an aftermarket Base.

As far as having it professionally done, Im pretty sure even a chimp could port the Plenum.

Chris89GTA

iTrader: (2)

so what base would you suggest for the siamesing... i am buildin a 383 right now and for money sake am gonna put the TPI back on for a while... but heavily modified... or that is the plan now... i may choose to go superram before i get it running... but i am just wondering

Bort62

Well Chris,

Mike Davis did pretty well with his Siamesed Base, But he Siamesed it to the extreme. Other than that there really isnt much hard evidence, do a search and see what you come up with.

I have Siamesed my base in about 4". How much will it help ? I don't know. Will be spring before I really know as right now the motor is on the stand.

The principal is sound, but we just don't see very much conclusive track or dyno data indicating yay or nay.

Chris89GTA

iTrader: (2)

thanks man... i am probably just gonna see if i can find a used base and just port and siamese the crap out of it...

Ed Maher

To answer the original poster, if you are saying you're limiting your options to buying an aftermarket base, or paying someone to have the stocker ported, then no question, just buy an aftermarket now. You'd spend almost as much money (if not more)on porting as you would on the new piece, and out of the box an aftermarket base will outflow (or come damn close anyway) even an expertly ported stock piece.

Hell i wonder myself if i shouldn't have just bought an aftermarket base rather than having spent all the money i did on a decent grinder and good cutting bits to do mine, but down the road they'll probably come in handy again so i guess it wasn't an all bad idea.

As to the plenum though, that can easily be done yourself. Unlike the base which you really need a real die grinder to do the work, even a dremel and it's basic high speed cutting bit has no problem on a plenum. And i'm sure you'd end up spending more than the $40-50 a dremel costs on having someone else do it anyway.

D Stroy H8

Maher is right (as usual)

For the plenum you'd want to port match to your runners by making each pair of outlets one big "peanut" shaped hole. Theres a very good pic of this example posted recently oin the TPI forum.
Lemme grab that -


Here! ----> https://www.thirdgen.org/techbb2/sho...hreadid=147622

MILT

okay, what is the "best" base? It seems like they're all about the same, and around the same price...

D Stroy H8

They are all really good.
The SDPC base modded for Vortec heads will allow you to use... Vortec heads! Which is good cause those heads rock for stock, and the SDPC base is nothing but an Edelbrock base which is gobs better than the stock piece.