The 4" Bore Thread

[stealth67vw]

moving up to heads, are there any other options out there that are street worthy other then:

Super Flows
Angle Flows
JPM's
?

IE anything my bank wont disown me over? 

Comp Eliminators

[Fiatdude]

The one rule about heads is -- Look into your wallet and see how much you can afford to spend -- lay it out on the counter -- -- -- --

Heads are the one thing that can really help the performance of your car and you won't regret the money spent

[andy198712]

Being possibly the most bang for your buck too I guess!

[58vw]

great pics mexx

THX Tim

What pistons do U prefer

MeXX

venolia are good...j&e also...trying a set of Cp's in new engine now..lighter for sure that the venolia..

[MeXX]

venolia are good...j&e also...trying a set of Cp's in new engine now..lighter for sure that the venolia..

Hi

What forging number do they have ?

I have tried till now: X100A and 28-1
The next I will try will be: X115 R

MeXX

[Shag55]

I have used Wiesco, JE, Venolia and now CP on the new motor. I love the CPs best. Oh but mine are just babies and don't fit I this trend. Only 92mm

[MeXX]

I have used Wiesco, JE, Venolia and now CP on the new motor. I love the CPs best. Oh but mine are just babies and don't fit I this trend. Only 92mm

Dear Shag

I've used Wiesco because they were of the shelf.
I've used Venolia custom pistons traditional design very rigid and forgiving.
I've used CP pistons X box forgings very innovative and professional design.

And Shag who says size doesn't matter ?      

MeXX

[Udo]

I have build one wbx engine with 101's for racing only , it has 280 hp with 51 carbs , he has run 10,9 in a street car this year . But i would never build this engine size with less hp for german street driving - autobahn -

Udo

[Eddie DVK]

I have build one wbx engine with 101's for racing only , it has 280 hp with 51 carbs , he has run 10,9 in a street car this year . But i would never build this engine size with less hp for german street driving - autobahn -

Udo

Why not not Udo?
I have been collecting parts for a 4'' type 4 engine, deutz cilinders(100mm) and JE pistons de rest stock. (71 crank, CU heads, hoping a JPM cam).
Is this not ok for street use? Because will be a street engine.

Regards Edgar

[Udo]

On a type4 it is ok , this engine has 12mm more space between the cylinders

Udo

[MeXX]

Why not not ?

I have been collecting parts for a 4'' type 4 engine, deutz cilinders(100mm) and JE pistons de rest stock. (71 crank, CU heads, hoping a JPM cam).
Is this not ok for street use? Because will be a street engine.

Regards Edgar

Dear Edgar

I'm 100% with Udo 4 inch with type 1 bore spacing (112mm) (doesn't matter what case: WBX, Autolinea, Scat, Autocraft, AF1; ARPM) is not good for street use.
The reason is the cooling or better the lack of it between the cylinders: if you have 112mm bore spacing and 101,6 bore there are 10,4 mm left for two barrels, cooling fins and space for cooling air for the bottom (hotter) side of the cylinders.
You have three possibilities:
1. Thin barrels cooling fins and space for the cooling air.  
2. Thicker barrels no fins and little space for the cooling air.  
3. Seamees cylinders with no space for the cooling air.  

UC

MeXX

[MeXX]

Dear Edgar

As there are a lot of 4 inchers on street U have some possibilities to overcome this problems:

Take heads with a lot cooling fins like Thorsten Pieper or JPM's.
Take nikasil instead of casted iron barrels lower friction means less heat and aluminum can transfer the heat better from the hot sections to the ones where there is more cooling.
If you take nikasil 100mm Porsche is better than 101,6 as it is thicker and superior in quality.
Run oil squirters and really huge oil cooler to transfer air cooling to oil cooling.
Low CR and low horsepower produces less heat. (but who wants a 4 inch low HP mill  )
Thinking of running E85 it would make everything much cooler.  

MeXX

[Udo]

Edgar has a type4 so he has original good heads for that bore .

Udo

[Shag55]

( And Shag who says size doesn't matter ? )
When it is N/A it does! Bigger bore = bigger intake=more power!
In my case ( turbo ) bigger bore = less efficiency, more heat and less strength.

[dangerous]

( And Shag who says size doesn't matter ? )
When it is N/A it does'nt! (haha)Bigger bore = bigger intake= less air speed=less power!
In my case ( turbo ) bigger bore = less efficiency, more heat and less strength.

I edited your post Shag, ha ha!

[Erlend / bug66]

( And Shag who says size doesn't matter ? )
When it is N/A it does! Bigger bore = bigger intake=more power!
In my case ( turbo ) bigger bore = less efficiency, more heat and less strength.

Kinda depense on what you are after. Most hp pr liter or most hp overall. The NA engines with the highest number of hp pr liter must combine the fastest airspeed, most flow, most suitable bore and optimal stroke to push out the hp it needs. Or you can build a 3liter type 4 with 300hp.

It's much, much cooler to have 235-245hp from a 1915cc than 300hp from a LARGE type 4 

[Shag55]

How about 375 or more from a 74x108, or 230 from a 74x88?
What about turbo motors?

[Erlend / bug66]

How about 375 or more from a 74x108, or 230 from a 74x88?
What about turbo motors?

Nice numbers

Turbo beats it anyway

[dangerous]

How about 375 or more from a 74x108, or 230 from a 74x88?
What about turbo motors?

  Hi Shag, Turbo motors will likely benefit from the large throats,(and bores)
but it is a bit hard to tell, since there are good numbers from even small bores.
Even tiny engines make great power with boost so long as the tune is right.

No disrespect to anyone with my observations,
but if you ignore dyno claims,
and use MPH and mass, to align the scale:

I can only comment what I have seen,
and by using track performance as a bench mark/datum,
I have never seen any VW engine show better than about 340,
that is Super street and pro stock record MPH's.

None with 108 bores and huge valves.(the large valve/throat cross section being my sore point)
Perhaps if the 11 or 12000rpm were used to get the air speed up? who knows.(or longer strokes).
I am sure anything is possible, but yet to see any record numbers from the big bores and large valves that normally go with them.

The other problem is that because most classes are capacity limited,
the large bore means short stroke, and even with rod lengths under stock,
it just agrivates the air speed issue.

Type 4's?
I can only think of two N/A ones in the world that are around a real 300hp(calculated from MPH not imagined),
and I'l bet they are either big cc or have smaller(<54mm) valves and likely comparitively short rods.

These are only my viewpoint on what(how) i see around the traps.
I hope my comments give food for thought and generate some discussion.

[Shag55]

I'd say you may be right. Until we see he #s equated from MPH they we all just figures from a dyno.
Pats motor I believe is in the Neighborhood of 330 at pro stock weight. Roger Crowfords pro stock motor is there also as well as his super street motor and its 82x96.5 bore

[Udo]

As far as i know one of the fastest super stock engines only has 90,5 bore . with 86 stroke something about 270 hp ...
So i think that big bores do not make the power. but the heads do
Udo

[Shag55]

That's a different scenario Udo. Valve size limited. The 90.5 bore has a better intake vale to bore ratio at 49%

[MeXX]

Hi

latest pix from my version of a street 4 inch mill

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Bare Competition Eliminator with Beryllium seats installed

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Stud holes drilled

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Step for the combustion chamber and head gasket milled

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Porsche nikasil barrels and billet spacers installed.

MeXX

[Shag55]

Nice, are those CEs? What valve size and bore?

[MeXX]

Nice, are those CEs? What valve size and bore?

Dear Shag

Yes these are CE and I bought them as bare castings;
51,4mm intake valve 40mm exhaust valve
100mm bore Porsche 993 nikasil barrels.

MeXX

[Shag55]

Perfect! 51% of bore. If these are to be street heads then will you use an oil bar for cooling?

[MeXX]

Perfect! 51% of bore. If these are to be street heads then will you use an oil bar for cooling?

THX Shag
I run oil squirters on all engines street or race.
I run huge oil coolers to cope as much cooling as possible by oil

MeXX

[ibg]

Dear Mex, what stroke are you using as the barrels look fairly short!
Do the spacers 'extend' the barrel to stop the piston cocking at the bottom?

[MeXX]

Dear Mex, what stroke are you using as the barrels look fairly short!
Do the spacers 'extend' the barrel to stop the piston cocking at the bottom?

Dear Ian

As Porsche uses only 76mm stroke this barrels are very short. Maximum stroke U can run is 82mm,
the spacers a necessary to get the right height with Autolinea case and 5.400 rods.

MeXX

[Frallan]

My 104 mm JE. 440 g with CNC copied dome from my E-Plus heads.
71 mm stroke.
5.325" rods