I have chance to get an entire TPI unit for $50. Thinking about porting the base and upper plenum as suggested. For $50 plus my time to clean it up/port it - would the torque/HP gains be worth it over buying an after market set up? (i.e. Big Mouth base)

I figure porting a stock unit plus some Arizona Speed and Marine runners should net a very noticable difference over my existing stock set up.

The seller thinks it's an 1989 unit- are they all direct bolt ons to my 91 ?

Also, seems like all the testing/posts I've read show that the Arizona Speed and Marine runners provide the best torque gains from 200-4500 rpm's ?

Any thoughts ?

Gifman

 

Gifman, I cannot give you "technicall" gains of porting the base. I can tell you that I have ported my own base and plenum on both of my cars. I have felt the gains on my IROC. And I cannot complain about performance in my slower RS. For a poor man, it was defiantly worth the time I spent doing it. I have seen an Edelbrock TPI Intake up close. I believe, don't quote me, that it is the same as the TPIS. The runners on the Edelbrock base have a much larger diameter than that of a stock or ported base. The difference is more that I can describe, you have too see it to know the difference. All of the numbers and literature I have read have indicated that the a "big mouth" base is far superior to that of a stock or ported base. Basically the ability to flow more air = the ability to make more power.

There are obviously more factors. 350 or 305. Mild or wild or in between. Additional bolt on's. Money vs. little money. If money is not a concern, get it. I believe a "big mouth" could gain between 25 - 35 HP(maybe more). I will one day decide between the "big mouth" & "mini ram." But for now I am too satisfied with my ported intake to put money into an intake. There are other fish to fry for me.

About the intake and will it fit. 87 & up intakes fit 87 and up SBC heads except vortec, LT1 & 4 & LS1. It sounds like you will be ok.

I hope this helps,
Rob

 

You'll need to plug off the cold start injector passage, but that's about it.

Stock bases suck. Ported stock bases suck less.

 

Siamese the base.
Who was it on here that had the "guide to TPI base siamesing"??

If I remember right the gains were pretty impressive . . .

 

The gains can be very nice, but you run of the risk of starving one or two cylinders and that can kill the engine off in a matter of months.

Its a calculated risk, and the better you are at porting consistently the less risky it is, but still... scary.

 

My old one from my Formula is going under the knife :-)

I have to reseal the intake on the GTA since its starting to leak some coolant so in spare time at work and after I've been hogging it out :-)

Results seem fairly impressive since everyone says theres not enuff metal to hog out .... I'll admit u wont get gains like stepping to a edelbrock or accell base, but ive still opened my runner openings up to almost 1.7 (1.65-1.69) inches vs. the 1.48-1.5 ish i had before i began porting them out :-) Might get ballsy and try and go for 1 3/4 as far as i can push it......Running out of sealing room on the runner side though, not sure how little i can leave and still gaurantee a good seal

Figure a 10-15% gain in size, so there is some room to spare not too mention I had significant piles of aluminum shavings..

For getting the innnermost reaches of the runner and the worst choke point your going to need a min 6 inch burr with the oval shaped alum cutting bit and a smaller ball style with a min 6 inch ext should help as well ...

my thoughts for now

LAter
Jeremy
PS If u have it laying there and want to practice porting or cant afford another aftermarket base right now, by all means go for it

 

Who all is using the TPiS big mouth intake? I keep hearing contradicting things about TPiS.