Few Questions on my 2270 build spec

[Haveacamper]

Hi Guys,
I lurked her for a while back in 2007 when I was looking at rebuilding my CJ motor in my kombi - but alas went down the Porsche SC root.

7 years later I find myself moved from UK and now living in Aus, and now looking at building up a type 4 motor for my next project - late street superbeetle.

So fare I'm looking at the following:

2270 (78x96)
96mm Keith Black pistons
78mm Forged crank,
Forged H Beam 5.328 Rods with arp2000 bolts
Web 86B Cam
51gms supervee type 1 lifter with bronze inserts
AMC Heads worked to 44x38 with cromoly valve seats, hardened tophat guides,8mm conversion on exhaust guide, single valve spring spaced for cam. fully ported. expecting 55-56cc Combustion chambers
melling h-duty oil pump

light-weight flywheel
1700 KEP clutch cover
daikin clutch disc

Exhaust is likely to be equal length headers with 150mm vintage speed superflow muffler

FI system will me megasquirt ms3x and hoping to go fully sequential with COPs

cooling system: i'm currently weighing up between DTM, one of porsche fan conversion kit, and making my own porsche fan conversion setup. I realise there is a lot of info on this site specifically about the topic of cooling, which i'm currently reading up on

I have a few questions regarding what I have so far and what direction should I go down. If you wouldnt mind giving your opinions with reasons that would really help me.

1) i have asked in the FI section, but may as well put here as I'm asking other q's. What throttle body diameter would you recommend? I've been reading up, on here again, regarding necessity for maintaining air velocity and throttle resopnse etc. etc
2) I have the option of choosing whether I have CJ or CU exhaust port profiles. Does one have a benefit over the other - oval or rectangular? As i have yet to purchase the exhaust I can go whichever one is best
3) What kind of CP should I be targeting?
4) any other recommendations welcomed

Nath

[Clatter]

My $.02, FWIW...

Might consider taking the rod length up a smidge to 5.4 to move the rev range up?

Type 4s love dual-pattern cams. Maybe consider the 163/86b or 86b/86c?

You will want dual springs either way.
Only if you go super-light on the rest of the valvetrain - Ti retainers, aluminum pushrods, etc. will you be able to get away with single springs on those type of cams.

Melling pumps leak, and are too big, IMHO.
I go over this ad nauseum on my build thread..

The VST exhaust would be like a restrictor plate on a motor like this IMHO.
While they look really cool, and are high quality, easy to install, and have an O2 bung already,
Nobody would ever DARE run one on a dyno, especially on a big motor.

Tangerine or A1 for exhaust.. Anything with a collector, actually, would be better than just a 'can'.

Search for user 'Sandeep' for info on the Porsche shroud;
A wealth of info about making the (supposedly?) poor-cooling P-car shroud cool anything like an (admittedly ugly) DTM

Few true performance exhausts are made for square-port heads;
There are inherent limits to how big the square exhaust ports can be made without welding.

CP = CR?
Depends upon the cam and fuel you plan on running.

Sounds like a fun motor. You're on the right track..!
Building one like it myself,
After waffling/ruminating on it for a dozen years or so..!

[Haveacamper]

Thanks for the info. Regarding the dual springs. Stateside Tuning in the UK are most probably supplying me the parts and I believe they have their own springs made up specifically for every application. I did read however, that the Web 86B cam calls for a dual spring. regarding the pushrods - aluminium is on the cards.

Thanks for the heads up on the exhaust. even the VS "super flow" would be too restrictive....I'll look into the tangerine and a1! based on the availability of squareport exhausts I think oval is the way to go. Especially as there is no real difference in performance etc.

Ye I meant Compression Ratio. cam choice is looking like Web 86B and fuel is likely to be running super unleaded which is 98 over here.

p.s. i've started reading your junkyard buildup. very informative and i'm only on page 2