is a 4 branch really neccessary with a big valve head? experts needed!

[paultownsend]

iv a reasonable spec engine in my 91 8v gti

40/35 'big valve' head
newman 268- looking to change
matched inlet/exhaust manifolds
2.0 agg tall block
'hotgolf' lightened fly
milltek manifold back system

this spec made at midland vw with only ignition timing adjustment-

134hp@5712rpm
144.6 lbf.ft@4515

i only wanted an indication of output and jody there did a good job and health check. its certainly not as optimistic as stealths figures! but both figures seem relative

the engine pulls really well down low (2k), and the first 4 gears will pull into the red easily. this is something i really dont want to loose.

i know the newman 268 is a little 'tame' but wonder if i change cam, (272, 276) il loose that drivability lower down. i really want to make nearest to that 150bhp as iv spent enough on the engine already, and its a real good, strong engine, and i need an excuse not to put an abf in there (so dont suggest it!) - cam suggestions please 

now, tsr are now distributing a milltek 4 branch for the tall block conversion now, and are promised to fit a treat. im very interested as my head should be flowing a fair bit now, esp at higher revs. it has a flexy on it, so shouldn't crack, and as long as i shield the bay, are there any disadvantages. or more to the point, what are the advantages. will this flow better than my reasonably ported std cast manifold. its alot of money at the moment, but i can justify it to finish the car off properly. and should it be complimented with a new cam?

Paul

[DarnPB]

You can gas flow your original manifold and gain nearly as much as a tubular manifold.
A tubular manifold though would be better for exhaust scavenging though and assist gas flow from your cylinder head, provided it has been made and dimensioned properly.

[paultownsend]

when i went to pick up my milltek exhaust from the factory, as i live close, they had an r8 on their dyno they were doing a production header, cats, and full system for.

when you see it with your own eyes its amazing. i just do not doubt their quality. and they have sold thousands for golf's through tsr.they are also the same as the tsr ones, just an inch taller to fit the taller block.

my manifold was said to of been ported, but i just dont see how it could flow like a 4 branch. my head just seems to flow so much more, it just pulls real hard to the red, it never did that before!

[Diamond Hell]

Recently had an ABF (sssssshhhhh) on the rollers - only thing different was a tubular manifold and no cat.

It scored 173bhp.

You've got the potential for improved flow through the head, with your porting and big valves - a well-designed 4 branch will realise that improvement.

[danny_p]

tubular manifold will help, would like to see your rr  printout  but guessing you need more fuel as well

[Thom89]

You can never throw too much money at good engine, go for it!
Tom

[dubslug]

how would u go abt improving fueling on the digi 8v??

[paultownsend]

il try see if theres a scanner at work for the printout

[MarkS]

Interesting thread this, as I am looking to do near as makes no difference the same mods to my 8v

I probably would run a wilder cam
276  and adjustable vernier

They are some good figures!

What work has been done to your inlet manifold?

With regards to increasing fuelling, I don't know for sure but maybe try-

http://www.bahnbrenner.com/vw_audi/products/459/3_5_Bar_Fuel_Pressure_Regulator ?


Also, have you considered running megasquirt?
I'd love to use it, but I think I'd struggle to understand it at the moment

[danny_p]

just shoveing a higher pressure fuel reg in there is sub optimal,  did that on TC's  car just to see what diffrence it made,  it's still in there and it goes fine up top,   that was a 4 bar reg instead of a 3   but on the cold start it runs awful so you should really tweek the fuel map as well