# guideline to modify N.A engine



## HPR (Oct 31, 2004)

I see a lot going on here and people like to grab too often to parts or technologies that are far too extreme for their goals, sacrificing driveability and reliability.
And they bring not always the gains that are expected....
IMO 99.5 % of us don’t need these parts below …I have them all seen here on vortex
Titanium valves
14 mm lift cams
+ 300 degrees Cams 
Mech. lifters
C.R 14/1 
Dry sump systems.
Too big ITBs
Billet crankshaft
Once the engine is run above 7500 rpm, it goes at the cost of Torque
and its not needed unless more than say 125 hp /L are expected

Bores bigger than 83,5 mm
Except if you want to build a + 190 Fw hp 8V or + 250 fw hp 16V/20V 2.0 L engine…
.and even then its not always needed.
Many off these parts are used to get the last 5-7 % out
Races are won on TQ , not ultimate HP 
( the ability to climb the revs / were the most time is spend )
you DON’T need 8000 rpm to make decent power 
The best N.A / 2.0 engines make very serious powerlevels @ 7000 rpm ! 
( 260 / 270nm @7000 rpm )
N.A tuning is doing the basics right and do many small things that ad up
You can find maybe 20 to 30hp just by making work on the small things that are too often overlooked.
So here a list with things you can work on 
Friction
The higher the revs the more frictional losses.
build the perfect NEW ``WORN`` engine
( a few 0.01mm on crank /rod bearings and Bore)
Flywheel /crankshaft and Piston /rod weight reduction 
Balancing crankshaft, pulleys, flywheel, clutch, pistons, rods, etc
Valve train component weight reduction
Valve Spring pressure
Belt (s) tension /tooth shape
Oil seals 
Coated bearings / piston skirts
Piston rings
Surface finish (roughness)
smaller alternator 
make all water and oil flowing well
Compression Ratio
big gains can be made here , but go not in extremes
Cilinderhead assembly
This is the most important part to make power.
I think there is enough info on that available, just a few things,
Don’t make the valve guides too short, this compromises valve sealing. 
( even if it cost some flow )
Its not the size of the valve that matters, it’s the throat under the valve that matters.
Symmetry on ports and valve height 
sand paper port walls to avoid wall wetting ( less flow )
But the best head and cams will not work if they are not proper timed and inlet an exhaust system are not in Tune
Cooling 
Run your engine cool 
this helps to reduce inlet air and under bonnet temperatures
above 70 C there is power loss
electric water pump 
bigger radiator
Lubrication
Sump with oil control baffles
Crank oil scrapers 
Windage tray 
good air ventilation bloc and head
oilcooler
Fueling
Keep fuel cool
Higher fuel pressure 4 -8 bar
High flow injectors with good atomisation
Put the injector 15 to 25 cm from the valves so that the fuel/air has time to mix
Use good /race fuel and do the ECU mapping on this fuel
inlet /ITBs
1600 / 4 cil 42 mm 
2000 / 4 cil 45 mm ( 48 mm on a FULL spec engine )
Keep heat away from inlet manifold / ITB
Powergasket
Airhorn length and shape
Use airhorns with different lengths in one setup
don’t use an airbox as it will bring more hp
in theory there is a gain because off pulses in tune with an airbox / plenum
but in praxis its VERY hard to achieve by try and error
and who has acces to CFD software as WAVE / VECTIS ?
Exhaust
A long 4-2-1 or 4-1 header / diameter 41 to 45 mm
63.5 mm system 
Wrap or coat headers 
i know its far from complete and but in the end......
its not all magic , but a lot common sense....



_Modified by HPR at 5:41 AM 9-25-2009_


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## billyVR6 (May 8, 2000)

*Re: guideline to modify N.A engine (HPR)*

Excellent post; especially the part about what you *don't* need. http://****************.com/smile/emthup.gif


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## Sciroccoracer7 (Apr 28, 2005)

Darn I have almost everything I don't need on my daily lol


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## LT1M21Stingray (Sep 14, 2006)

*Re: guideline to modify N.A engine (HPR)*


_Quote, originally posted by *HPR* »_... Keep heat away from inlet manifold / ITB


Don't paint it black. Leave it bare aluminium or paint it silver.



_Modified by Mtl-Marc at 2:36 PM 10-14-2009_


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## tdogg74 (Mar 1, 2002)

*FV-QR*


_Quote, originally posted by *Mtl-Marc* »_
Don't paint it black. 


why?


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## LT1M21Stingray (Sep 14, 2006)

*Re: FV-QR (tdogg74)*


_Quote, originally posted by *tdogg74* »_
why?

"Black absorbs heat and Silver reflects heat."
A. Graham Bell


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## tdogg74 (Mar 1, 2002)

*FV-QR*

The color black absorbs light, which from sunlight, absorbs all the colors, which results in heat. 
Going by that logic, everything under the hood should be painted white.
What does the color have to do with anything if there is no light? Regardless of color, ambient engine heat will soak through any part, regardless of its "color".
The only thing that would reflect the heat in in engine bay is the material coating the part. (ie: header wrap, ceramic paint, metalized polyamide polymer laminated glass cloth, ect)


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## stickman (Jan 16, 2001)

*Re: guideline to modify N.A engine (HPR)*


_Quote, originally posted by *HPR* »_Bores bigger than 83,5 mm


Great post. However I must disagree with you on this point. As long as you cause no problems, the bigger the bore, the more power you will make. Some people have issues with thin cylinder walls, but there are people that sucessfully run bores larger than this.


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## VWn00b (Mar 4, 2005)

*Re: FV-QR (tdogg74)*

Travis,
I plan on covering alot of things on my new motor with gold tape rolls from HRP World.
http://www.hrpworld.com/index....oduct
Going to do the back of the block, back of the head and valve cover, and a good amount on the firewall.
Only thing I'm not sure of is how well this stuff stands up to different weather conditions.


_Modified by VWn00b at 7:55 PM 10-20-2009_


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## HPR (Oct 31, 2004)

*Re: guideline to modify N.A engine (stickman)*

From 84 mm onwards you can have thin cylinder wall issues , some have them…
And others run successfully bores up to 85mm But IMO its always a risk…
Up to 2105cc on 85 mm bore and some extra flow, make some more power 
Target is to stay away from problems before they arise… so 83,5 mm is the safe option


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## VWn00b (Mar 4, 2005)

*Re: guideline to modify N.A engine (HPR)*

I'll be running 84mm Wossner pistons in an ABA block.
From what I've read around here it seems like 84mm is safe.


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## HPR (Oct 31, 2004)

*Re: FV-QR (VWn00b)*

On heat shielding have look on
http://www.nimbusmotorsport.com > tech. archive >nimbus …
http://www.pegasusautoracing.com > exhaust > heat barriers
http://www.heatshieldproducts.com


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## stickman (Jan 16, 2001)

*Re: guideline to modify N.A engine (HPR)*


_Quote, originally posted by *HPR* »_ From 84 mm onwards you can have thin cylinder wall issues , some have them…
And others run successfully bores up to 85mm But IMO its always a risk…
Up to 2105cc on 85 mm bore and some extra flow, make some more power 
Target is to stay away from problems before they arise… so 83,5 mm is the safe option


I have run 84.5mm since 2001 with no problems at 11:1 compression.


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## HPR (Oct 31, 2004)

There is no universal rule for all engines 
On the street you come away with it and for relative short periods at full load.
With high cylinder pressures and longer periods under full load its another story
In real racing conditions every part is so much more under stress (circuit racing) 
on a N.A Audi A4 2.0/16V 300+ hp works engine build by Audi Sport they change the head gasket (85mm) at 2000 km and sometimes it blows trough sooner !
I started this tread to explain that its possible to make a serious powerful engine by using parts that are not to extreme.
To build a balanced system
And to look to some basic things that come at low cost 
Just a bit less tension on the timing belt is a 1 hp gain
Just to keep it on the safe side 
Until you arrive at a point you have already serious power and need to go a step further 

The DON`T part > Now a strange story 

Bought a small sound system
SOUND GOOD
Turn it loud 
PROBLEM
Bought the biggest speakers I could find
NO SOUND
Big Amplifier
SILLY SPEAKER WIRING GLOW RED HOT
decent speaker wiring
GREAT SOUND and LOUD 

.... well that is what a balanced system is all about
and with cars or engines its no different




_Modified by HPR at 1:11 PM 10-22-2009_


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## LeftcoastTigger (Dec 31, 2009)

*Re: guideline to modify N.A engine (HPR)*

Compliments of the Season, HPR!
Your post was well timed, as we've been collecting assorted components to create an ABF hybrid and would really appreciate your advice! 
We have a complete 1995 North American ABA 1984cc 8v OBD1 steel crank and squirter engine assembly with wiring loom & ecu; plus a similarly complete 1990 9A 1984cc 16v, from which we will create a strong street ABF hybrid with emphasis on driveability and a nice flat 150 ft/lbs torque curve, probable 6,000rpm maximum
We plan to use the 16v Bosch Motronic system as others' have tweaked it to support over 200fwhp, we have parts including variable fuel pressure regulators at hand, and can remap its fuel mixture and ignition timing to suit - - 
Assuming an appropriate level of experience, skill, and creativity is available plus a genuine 10.5 : 1 compression with 83.00mmd OE pistons, please comment on the following:
Can you please post air flow figures at 10" water for the 7 mmd stem, 34mmd intake and 29.5 mmd exhaust valves of the engine you described? 
We also have available 5.5 mmd stem, 33mmd intake and 29mmd exhaust valves, which we would expect to flow similar volumes with the advantage of lighter mass (not that we need it), less chamber shrouding and, assuming valve seat od's do not exceed that of the valve, more material around both spark plug bores and coolant jackets
Our cylinder head casting is #051103373 - - can the combustion chamber or piston crown be reshaped to increase the percentage of squish created at TDC without excessive decking of the block?
We believe our application best suits a tri Y header with 1 5/8" x 14" - 16" primaries, 1 3/4" x 30" - 34" secondaries, and a 2 1/4" x 12" outlet running into an approximately 4 litres volume exhaust box before continuing into the standard rear muffler - - does this agree with your experience?
We can choose between 52mm id ABF and 50mm id KR intake manifolds, to which we expect to adapt or fit the standard 9A TB with its 35 and 52mmid bores - - is this likely to be too restrictive? 
Since there is 2.5mm between the TB bores we could fit a 54mmd secondary butterfly and reshape the throttle shafts, but doubt we would gain sufficient flow to justify the effort - - are larger, similarly progressive TB's available?
We have several pairs of KR and 9A camshafts available (but no ABF, hint, hint), are aware that exhaust cams can be modified and used as inlets, and have both adjustable belt and inter cam sprockets - - disregarding the oe cams, what lift, duration @ 1.00mm and 0.50", and overlap would you suggest?
Do you know of anyone who has bored and cross drilled the lower manifold runners of an oe 16v manifold, fitted appropriately sized butterflies, shafts, linkages, idle and WOT switches and oe Motronic injectors, then an adapter in place of the oe TB in order to create a hybrid ITB system managed by the oe Motronic components?
By how much would you change the camshaft specifications if fitting a set of conventional ITB's? Ignition timing too? 
What maximum spark advance would you suggest at WOT, at what rpm should it begin, how many degrees should timing advance at 15" vacuum, is vacuum advance rpm sensitive, what make and model spark plugs would you suggest, and should any oe Bosch ignition components be replaced in this application? Phew! 
Since Oettinger, Drake, and Graf 16v heads are unobtainable to us mortals, we wouldn't like to bet against 2003 - 2006 FSI 1984cc 16v heads being adapted to ABF or similar short blocks - - 
If useful to you or our fellow Vorti we could comment further on the planned specifications
Happy New Year to all!

_Modified by LeftcoastTigger at 11:35 PM 12-30-2009_


_Modified by LeftcoastTigger at 11:58 PM 12-30-2009_


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## HPR (Oct 31, 2004)

Thanks, glad you like this post..
Car manufacturers spend weeks to design /optimise an inlet system for a specific engine to get equal filling and gas dynamics, dont throw this away !
The complete ABF manifold works great on a ABF or 9A
And many would be surprised, what this manifold is capable off
the 9A TB compares with nearly a 63 mm TB 
the ABF is about 65 mm and more than big enough for 250+ hp
About a manifold for ITB`s there are many on the market ,
but very few that work well and fit well.
Head 051 103 373 D
Head gasket ABF steel multi layer
33 mm inlet valves works best ( bore 81 > 83.5 mm ) 
For 34 mm valves you need 84 / 85 mm bore to make them work
27 or 28 mm Exhaust valves make on the dyno very similar results 
KC engines make about 270 hp on STD size valves ( 32 / 27 mm )
Audi 3.6 V8 DTM used 33 / 28 mm valves (bore 81)
We used schrick 276 hydro`s with good results
But for a streetable on 10,5 CR and 6000rpm , 
I would try 260 cams (on ITB and std manifold )
the std pistons CR10,5 /1 will be more 10/1 
and for a good TQ you need some compression 
I would use a wiseco 11 /1 ( or something like that )

Exhaust is a tri Y header with 1 5/8 x 23.5 `` primaries 
2`` x 12`` secondaries into a 60mm tube and then 63.5 mm with no silencer
ignition timing is 26-30 degrees at full load
The FSI head is made in std spec as a A4 ST cylinder head 
( big valves, 2 squish zones, good ports and flow )
I have not looked if it is possible to mount it on ABA / 9A / ABF block 
But potential would be Mega 
Audi A4 ST 305 hp engine :
http://www.clubgti.com/forum/s...87653
_Modified by HPR at 5:41 AM 1-1-2010_

_Modified by HPR at 8:05 AM 1-1-2010_


_Modified by HPR at 8:24 AM 1-1-2010_


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## ps2375 (Aug 13, 2003)

*Re: (HPR)*

Are there any advantages to going to a low press coolant system and using a coolant such as "Evans Coolant"? As opposed to straight water or a 50/50 mix. Along with the 65-70* thermostat and fan control.


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## LeftcoastTigger (Dec 31, 2009)

*Re: (HPR)*

Firstly, this is my second post and first attempt to respond to others' remarks - - I hope the quotes are correctly outlined, with my remarks below - - apologies if not - - just in case, I've placed (parenthesis) around HPR's original remarks - - 
HPR, thanks for your response, and no doubt many others also appreciate your sharing such knowledge and experience
I will assume my previous questions regarding piston crown squish, conversion of oem manifold to hybrid ITB, and vacuum advance touched on subjects where you possess either proprietary knowledge, none, or insufficient time to respond, so will not repeat them 
Regarding my component choices, I previously neglected to mention that exhaust emissions testing and visual engine & exhaust systems inspections are a fact of life through much of North America, we must be subtle if our goals are to be achieved, and we choose to welcome rather than reject this challenge
Additionally, whilst we have access to the oem components mentioned in our first post, not all are on our premises and neither can they be evaluated without purchase, hence our hope that others might contribute any data at hand 
(Car manufacturers spend weeks to design /optimise an inlet system for a specific engine to get equal filling and gas dynamics, dont throw this away!)
Agreed, restrictions in contemporary designs appear due to inter departmental interference, such as Marketing over ruling Engineering in order to position the vehicle in a particular market segment

(The complete ABF manifold works great on a ABF or 9A
And many would be surprised, what this manifold is capable off)
Can you confirm the ABF, KR, and 9A intake runner i.d.'s are indeed 52, 50, and 48 mm? This seems unlikely as the 9A manifold at hand measures 50mm - 52mm od about 40mm either side of their joining flange. Whilst it appears all three share a 36mm cylinder head to plenum runner length, we presume the 1781cc KR plenum volume is less than the 1984cc 9A - - are the 9A and ABF plenum volumes different?
We note the KR runners' restricted section adjacent to the spark plugs is not proportionally reproduced in the 9A manifold, and that the ABF runners may have a constant i.d. without a similar restriction, presumably to better match each engine type to it's expected use - - 
(the 9A TB compares with nearly a 63 mm TB 
the ABF is about 65 mm and more than big enough for 250+ hp)
(About a manifold for ITB`s there are many on the market ,
but very few that work well and fit well.)
We suspect fitting individual throttle plates to each VW intake runner as first described would gain 90% of known ITB advantages whilst appearing sufficiently oem to satisfy "under hood" inspections, the illusion continued by gutting and refitting the oem TB to it's manifold
Any suggestions as to which standard manifold assembly might best suite our high torque application, and whether that choice would change if fitting the oem manifold with individual butterflies as previously proposed?
Of purpose built aftermarket 45mm ITB's, would you suggest the Badger, Jenvey, TWM, Extrudabody, or other systems?
How many inches of water vacuum at WOT would you consider acceptable at the various choke points of an off road high performance induction system, and what would you consider acceptable for street use?
(Head 051 103 373 D
Head gasket ABF steel multi layer)
Previous threads suggest 051 103 373 D is the assembly fitted to ABF and ACE engines, comprised of casting 053 103 351 C and 27mmd exhaust valve 051 109 611 B, which reputedly generates superior flow compared to 28mmd valve fitted to other heads, all possessing identical seats
(33 mm inlet valves works best ( bore 81 > 83.5 mm ) 
For 34 mm valves you need 84 / 85 mm bore to make them work
27 or 28 mm Exhaust valves make on the dyno very similar results 
KC engines make about 270 hp on STD size valves ( 32 / 27 mm )
Audi 3.6 V8 DTM used 33 / 28 mm valves (bore 81))
The stock 16v head obviously lacks volumetric efficiency, firstly due to parallel exhaust valve and cylinder bore axis creating both a restrictive right angle turn at the bowl and severe shrouding at the cylinder wall; and secondly as it appears oem valve head o.d.'s are the same or even larger than the seat, the latter resulting in a throat flowing less than the valve's potential
Further, if the 33mm in & 28mm ex valve combination is chosen, and the valve insert seats machined to create a 2.0mm wide contact face whilst taking full advantage of the valve o.d., the valve seat insert i.d.'s would be 29mm and 24mm respectively, and the insert cross sectional widths (original o.d. minus new i.d.) would be 33mm - 4mm = 29mm from 32mm = 3mm divided by 2 = 1.5mm for the intake insert wall thickness, and 28mm - 4mm = 24mm from 28mm = 4mm divided by 2 = 2mm for the exhaust
No insert with these dimensions could survive unless the seat to throat transition is generously radiused by 2.0mm or more, or my measurements or math are out - - 
The sectioned 16v head posted by Brian G http://www.clubgti.com/forum/showthread.php?t=193826 suggests there's sufficient room to increase the insert o.d.'s to say 34mm and 29mm respectively, plus modify the bowl areas especially the exhaust, without breaking into a coolant jacket - - postings by Club GTI mention several respected UK head modifiers, do you or colleagues know of any North American experts?
[edit of Jan 06, 2010: excellent flowbench thread at http://.clubgti.com/forum/showthread.php?t=182490] 
Customer evaluation is hindered as websites with flow bench figures are scarce, few state the vacuum at which tests are performed, whether the head combustion chamber concerned was affixed to a flow bench test cylinder with the same i.d. of the cylinder bores of the block to suck or blow as required, whether an appropriately sized length of exhaust tubing was attached at the manifold face, whether a section of inlet manifold or moulded plasticine radius was fitted around the inlet port at the manifold face, and whether figures were corrected for air temperature and humidity
Neither do they state what volumes of air pass through the port at specific valve lifts, which would provide some indication of when the valve/port combination achieved laminar flow, or in fact whether it did at all! 
Do you know of any sites which have posted authoritive tests?
Non the less, we have enormous respect for those builders achieving respectable results given the head's disadvantages!

(We used schrick 276 hydro`s with good results
But for a streetable on 10,5 CR and 6000rpm , 
I would try 260 cams (on ITB and std manifold ))
Neither Schrick nor the Distributors we have found post max. lift, duration at 1.00mm and/or 0.050", opening and closing degrees, and lobe centre/overlap figures, without which meaningful comparisons are impossible - - can you recommend a site?
The 6,000 rpm figure in our first post anticipates maximum useful rpm when emphasising drivability and torque vs hp rather than maximum rpm 

(the std pistons CR10,5 /1 will be more 10/1 
and for a good TQ you need some compression 
I would use a wiseco 11 /1 ( or something like that ))
We suspected the quoted 10.5:1 was out - - unfortunate as conventional or hyper eutectic pistons happily run with 0.05mm less clearance than even the best forged alternatives, which would be a poor substitute for this particular engine application 
(Exhaust is a tri Y header with 1 5/8 x 23.5 `` primaries 
2`` x 12`` secondaries into a 60mm tube and then 63.5 mm with no silencer)
Aha - - ages ago Flowtech of the USA was promoting similar "long primary tri Y" V/8 headers which raised some eyebrows as no dyno charts were offered for comparisons - - what other dimensions were tried before settling on the above diameters & lengths, how long is the 60mm tube before it diverges into the 63.5mm exit tube, how long was that to atmosphere, and are there any dyno charts available?
The approximately 4 litre exhaust box of our proposed system is similar to that suggested in an early rather than revised edition of The Scientific Design of Exhaust and Intake Systems and, as alert Vorti will note, co incidentally is similar to that of a gutted catalytic converter 
Approximately how many inches water pressure at WOT would you consider acceptable at the choke points of a high performance off road exhaust system, and what would you accept for street use?

(ignition timing is 26-30 degrees at full load)
On 93-95 RON unleaded gasoline?
(The FSI head is made in std spec as a A4 ST cylinder head 
( big valves, 2 squish zones, good ports and flow )
I have not looked if it is possible to mount it on ABA / 9A / ABF block 
But potential would be Mega) 
Yes indeed - - Issam Abed of INA Engineering recently posted an expose of the 5 valve AEB, the above mentioned 4 valve BPY, and the latest engine's 4 valve CCTC heads http://forums.vwvortex.com/zerothread?id=4430065 - - whilst others may have posted similar information, it seems Issam is particularly well informed as he continues to develop and market a wide range of performance oriented VAG parts
(Audi A4 ST 305 hp engine: http://www.clubgti.com/forum/s...87653)
This is a fantastic post from a group of well informed clear thinking professionals - - including one HPR - - most interesting even if I didn't manage to explore all referenced threads - - no surprise that the 16v Audi head was angle milled to help unshroud the exhaust valve, and what amazing numbers given the strict rules they had to work with!
Thanks again, this response turned into quite the epistle, no rush to respond if it means compromising your lifestyle or the information - -
p.s. Jan 06, 2010 - - apologies for the edits 

_Modified by HPR at 5:41 AM 1-1-2010_

_Modified by HPR at 8:05 AM 1-1-2010_

_Modified by HPR at 8:24 AM 1-1-2010_ 

_Modified by LeftcoastTigger at 9:05 PM 1-3-2010_

_Modified by LeftcoastTigger at 10:51 AM 1-4-2010_










_Modified by LeftcoastTigger at 9:32 AM 1-6-2010_


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## Tom A (Oct 20, 2004)

Related to this discussion, is there a formula somewhere for calculating intake valve size for a given engine? 
Maybe I am rusty on my algebra, but the formula in Water-Cooled Volkswagen Performance Handbook Greg Raven makes no sense.
http://books.google.com/books?...false
Punching in the bore/stroke for a 1.8 JH rpm*stroke in mm*bore in mm*bore in mm divided by 2,286,000 give me 19838, the square root of which is roughly 140.8. According to the notes, that should be my intake valve size in inches.








Using this calculator: http://www.wallaceracing.com/intake_valve.php for a JH up to 8000 RPMs tells me I need an intake valve of 1.56 inches, which is 39.6mm, or essentially stock.
The price for oversized valves is the same as stock ones, but looking at the head, It appears a larger valve would be partially shrouded by the cylinder wall if it is larger than stock, certainly at low lift.
Thoughts?


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## LeftcoastTigger (Dec 31, 2009)

*Re: (Tom A)*

Tom,
Thanks for contributing - - no doubt we're reinventing a 10 year old wheel, but it seems other enthusiast sites have deleted relative information
Superflow has a respected formulae for predicting valve sizes
Regarding flow balance, whilst many accept the rule of thumb which promotes exhausts flow at 80% of inlet, there's at least one very experienced and respected NCal tuner who believes 85 - 90% flows were a key component to his many NA successes, and was even better suited to turbo engines
Minimising the VW 16V exhaust port disadvantages certainly appears the greatest challenge - - as you may know 7mmd stem, necked intake and exhaust valves in both std and +0.5mm are available from http://www.importperformancepa....html the 5.5mmd stem valves mentioned earlier are blanks available from http://www.kpmivalvetrain.com
We suspect the above company's 5.5mmd stem 33mm and 29mm valves plus similarly sized powdered metal seats best suited - - valve guides yet to be found, likewise appropriate valve train components 
Do you know of any Nth American head modification experts with VW experience?


_Modified by LeftcoastTigger at 9:41 AM 1-5-2010_


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## Tom A (Oct 20, 2004)

*Re: (LeftcoastTigger)*


_Quote, originally posted by *LeftcoastTigger* »_Superflow has a respected formulae for predicting valve sizes

Is this formula online somewhere? I can't find it on their site.
Thanks,


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## LeftcoastTigger (Dec 31, 2009)

*Re: (Tom A)*

Tom,
I've misplaced the formulae since using it some 15 yrs! ago, and the wizard I worked with has gone native - - recently searched Superflow's website in vain, have emailed asking for online copies, will post when at hand 
If you haven't already visited it, the previously posted http://www.clubgti.com/forum/s...93826 shows a sectioned 16v head complete with custom jig with which to reference port datii
Club GTI evidently posted much other useful information some years ago; a few threads remain in an extremely time consuming format, others apparently joined the Digital Graveyard



_Modified by LeftcoastTigger at 9:38 AM 1-5-2010_


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## HPR (Oct 31, 2004)

Head : 051 103 373 D is on the casting ( above port 1-2)
About cam specs there is so much mist as all have there own measuring system 
but even if it is, were the cams build in symmetric and then both advanced / retarded or only 1 cam ?
in the end its the timing in the engine that counts 
and you always measure something... 
on flow numbers its a bit the same story , I agree measuring on larger bores ,pressure, radius, exh tube, etc
and I am bit sceptic on all sort numbers we find on internet about HP, TQ , CFM, CR , etc
its the TQ win races, and Hp sell engines story ,the same applies for CFM, CR
these numbers say something ,but need to be seen in the bigger picture …
but there is so much focus on flow testing , IMO its overvalued ..
Its what is( still) in the cylinders at the time of ignition that counts 
but the reliable info about flow, or dyno results are very scarce, 
About squish there is not much room for modification as the piston is already
0,7 mm above deck , count about 0,5 mm stretch from Rod, piston, piston pin , bearing clearances and you see there is only 0,2 mm to play with , any more is at risk for disaster 
wasted spark ignition and no vacuum used
26-30degrees is on ITB 45 mm and open exhaust 
Pump fuel Shell Vpower 98 is used 



_Modified by HPR at 11:22 PM 1-19-2010_


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## Tom A (Oct 20, 2004)

*Re: (LeftcoastTigger)*


_Quote, originally posted by *Tom A* »_aybe I am rusty on my algebra, but the formula in Water-Cooled Volkswagen Performance Handbook Greg Raven makes no sense.
http://books.google.com/books?...false
Punching in the bore/stroke for a 1.8 JH rpm*stroke in mm*bore in mm*bore in mm divided by 2,286,000 give me 19838, the square root of which is roughly 140.8. According to the notes, that should be my intake valve size in inches. 
Greg was kind enough to contact me to explain the formula in his book should say "Size in mm" rather than "size in inches" which still didn't make sense to me because I was screwing up the formula evidently. Working backwards today it is pretty clear I missed a zero on the 2,286,000. The annoying thing is I did it repeatedly, because it never made sense.
It does now, but the answer I get is pretty different than the calculator I linked.
Using 8000 RPMs, 86.4 X 82, the Raven formula says I need 45mm valves, which seem huge.

_Quote, originally posted by *LeftcoastTigger* »_Tom,
I've misplaced the formulae since using it some 15 yrs! ago, and the wizard I worked with has gone native - - recently searched Superflow's website in vain, so emailed asking for online copies, will post when at hand 
If you haven't already visited it, the previously posted http://www.clubgti.com/forum/s...93826 shows a sectioned 16v head complete with custom tool with which to reference port dati

That is a very interesting thread, it is nice to see the results of an unlimited budget. Unfortunately my engine is 8V so not a lot of it applies.
Thanks,


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## HPR (Oct 31, 2004)

Just adding onto this tread:

http://forums.vwvortex.com/showthre...out-of-your-N-A-motor&p=61855196#post61855196


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## aerowerks (Oct 19, 2005)

*tuning airbox*

there is a way to tune an airbox for ITB's without access to CFD software, all you need is a microphone to record the sound on your computer and some form of FFT (Excel has it) and some knowledge that people charge tons of money for


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