Alfa Romeo Forums banner

1 - 15 of 15 Posts

·
Registered
Joined
·
119 Posts
Discussion Starter #1
so i decided to kill some time and port my extra set of intake runners. i am not done but i wanted to post some pictues because i never knew just by looking at them that there was so much room for improvement. the picture of the head side shows where the overlap is when mating to the head. all i wanted to do was match it and found that if inclined i could take off quite a bit more. i am not thinking there is going to be any radical HP improvements, but they were in the garage and i was about to change out my runner couplings with some silicone tubing i picked up.
 

Attachments

·
Registered
Joined
·
1,230 Posts
Nice. It all helps a bit (although, the air flow meter is the major choke point in the system).

If you are keen, you can also cut the top out of the plenum and have a go at the top of the inlet tracts. A bit of work with the die grinder can give each of the throats a better profile. Afterwards you can either have the top tig'ed back in place or simply make a bolt on cover sealed with silastic.
 

·
Registered
Joined
·
119 Posts
Discussion Starter #3
i actually thought about fabricating a new plenum with the throttle body in the center, but that would not be for a while. optimumly i would like to go with the enlarged 52mm runners, but $$$ does not allow for it at the time. ditching the AFM is definately high on the list but that too will be a while before i can get to it. I have tried doing the bigger BMW AFM but there was something about it i did not like. it just never seemed to be tuned 100% no matter what i would do with it.
 

·
Registered
Joined
·
296 Posts
nice to see modifications on a budget!! making the most of cheap (ish) to source std components, then fettling to enhance performance instead of credit card type bolt on specials!
This is what old skool tuning is all about!! Nice job on them runners! why not make some new ones from steel (or stainless) when you do the one off plenum?!! ha ha food for thought
 

·
Registered
Joined
·
119 Posts
Discussion Starter #5
my thought with making new ones was that when i do the plenum i would make my own 52mm using the the stock runner base and some tubing bent on a mandrel bender. good thing i know a fab guy here in town who has one and can bend and fabricate anything i can dream up. maybe i will treat myself right for chritmas this year since the Alfa is not driven in the snow. then, when i head over there for this work i can take my stock manifolds with me and have him fab up a turbo manifold or two. hmmm. getting a little ahead of myself here. **** these cars!!!
 

·
Registered
Joined
·
119 Posts
Discussion Starter #6
Final Result

here is a pic of the finished runner. after measuring the intake side is 3mm larger and the taper out to the head side is a little over 5mm larger. there was more material towards the bottom to spread the hole and i know it goes against the original taper in towards the head to increase intake velocity, but hopefully i will not be dissapointed with the many hours it will take to finish the other 5.
 

Attachments

·
Registered
Joined
·
3,771 Posts
Hi, sorry to dig up an old post. Does it make more sense to bore out the standard intake runners like this, or use the OEM 39mm runners and plenum from a 164? 164 is bolt on, but the TB needs to be relocated or a diverter pipe mounted.

Mr. Gordon, if you see this, I read on one of your pages that you knew someone that could do larger runners for $400. Do you know if he still makes larger runners? Any details on the process?

Thanks!

Did you ever get a chance and see if your porting job made much difference?
 

·
Registered
Joined
·
1,736 Posts
After I saw this this thread I decided to have a lookn at my 75's inlet runners. What I found was best desribed as a piss pore effort from the quality control people at Alfa Romeo :mad:
Inlet runners that had very rough internal passage's.
2 big seams inside the runners from the casting process.
Less than consistant runner bore positioning (core shift during the casting process), that resulted in uneven material thickness and some shocking port misalignment.
Also I found the phenolic spacer always prodruded into the port and the small stubs on the plenum chamber are way too small in diameter.
I ported the inlet runners and the short stubs on the plenum chamber, and to me the car feels a bit livelier but this may well be the dreaded placebo effect. I deffinately nead a bigger airflow meter :D
 

·
Registered
Joined
·
111 Posts
Hi guys

Thinking about having a go at porting plenum/runner with my 75 TS engine (fitted to my Giulia Sprint)

Did you guys find it worthwhile?

I have bought a second-hand plenum for £30 to play around with without taking the car off the road.

Until i get to the throttle body and cams stage (£££££) I am looking at fitting a squadra chip and porting the inlet.

I already have an alcoholics exhaust. I'm hoping this sort of fettling might lead to modest increases, to perhaps 160 bhp or so, although to be fair I have not had the car Dyno'd as it is.

Feels pretty strong already, but trying to improve a little.
 

·
Registered
Joined
·
561 Posts
Thinking about having a go at porting plenum/runner with my 75 TS engine (fitted to my Giulia Sprint)
This is how I did it:

T-S Head

92 KW at the rear wheels (151 flywheel bhp) on 98 octane with BBR chip. After the work there was a notable increase in power (particularly 3000 - 5500 rpm). I would guess it has flywheel 160 bhp.
 

·
Registered
Joined
·
136 Posts
I have a set of the large cast intake runners for a V6 if anyone is looking for them. I am putting a 3.2 24 valve engine in now and have no further need for them.
 
1 - 15 of 15 Posts
Top