Bottom-End build ?

SHROSS
Wheel Whore
Posts: 31
Joined: Sun Jun 14, 2009 11:59 am
Contact:

Bottom-End build ?

Postby SHROSS » Mon Sep 07, 2009 7:52 pm

HI ! Guys ! Im busy building a NA motor for my drag golf mk1 . At the moment it runs pretty well in its 1800 set-up , but want to increase the displacement . I have a 2l cranckshaft from a mk3 GTI . I would like to fit the crank to 1800 block and re-bore it too max capcity . I want to know if anyone has done such a conversion and what piston con-rod combination would have to be used ?

I understand that the block might have to be skimed , in order to bring the compresion ratio back to its normal ratio ?

If anyone has done the above and has the sizes and combinations it would be much appriciated !

User avatar
MacMan
Lieutenant-Colonel
Posts: 4096
Joined: Sun Jul 28, 2002 12:05 pm
Car Make: VW
Car Model: MKV GTi
Membership No: 478
Location: Jo'burg
Contact:

Re: Bottom-End build ?

Postby MacMan » Tue Sep 08, 2009 8:31 am

SHROSS wrote:HI ! Guys ! Im busy building a NA motor for my drag golf mk1 . At the moment it runs pretty well in its 1800 set-up , but want to increase the displacement . I have a 2l cranckshaft from a mk3 GTI . I would like to fit the crank to 1800 block and re-bore it too max capcity . I want to know if anyone has done such a conversion and what piston con-rod combination would have to be used ?

I understand that the block might have to be skimed , in order to bring the compresion ratio back to its normal ratio ?

If anyone has done the above and has the sizes and combinations it would be much appriciated !


I have done a 1600 to 2.0 conversion. The 2.0 crank will fit in the block you have, but some clearancing of the block needs to be done.

The intermediate shaft gear will need to be machined in half to clear the number 4 conrod

Image


The oil pump mounting needs to be clearanced a bit so the number 4 conrod nut clears it

Image


The inside of the block by a mounting point needs to be clearanced so the number 3 conrod nut clears it

Image


Then you will need a 2.0 oil pump because the shaft is machined to clear the number 4 conrod

Image


Then use your current shortblock conrods with 40thou oversize Kombi 2.6 pistons (83.5mm).

No need to deck the block. A shortblock with a 2.0 crank, shortblock rods and Kombi 2.6 pistons means the pistons sit flush with the top of the block at TDC, with a compression ratio of around 10:1.

Image
'06 UG Golf MKV GTi - 208Hp / 322Nm @ KAR (DP + Intake)
| DIY+ | S3 short shift | Flowtech DP | ITG Maxogen | REVO2 | Autotech HPFP | RCD 510 | H&R |

Ex:
'04 Golf MKIV GTi.:R
'99 Citi Golf 2.0i

Patience is the ability to idle your motor when you feel like stripping your gears.

User avatar
Mk1
Major
Posts: 3236
Joined: Mon Jul 29, 2002 8:21 pm
Car Make: Vw
Car Model: MK7 GTD
Location: Uk
Contact:

Re: Bottom-End build ?

Postby Mk1 » Wed Sep 09, 2009 6:03 am

Very nice write up there mac man...
My trusty feet...
Rabbit power...

SHROSS
Wheel Whore
Posts: 31
Joined: Sun Jun 14, 2009 11:59 am
Contact:

Re: Bottom-End build ?

Postby SHROSS » Sun Nov 29, 2009 7:36 am

Perffect !!! Thanks bud !!!

User avatar
Wit Ark
Lieutenant
Posts: 1440
Joined: Sun Mar 29, 2009 8:46 pm
Car Make: VW
Car Model: Citi Chico baby dragster
Membership No: missing
Location: Namibia
Contact:

Re: Bottom-End build ?

Postby Wit Ark » Mon Nov 30, 2009 2:08 pm

A friend of mine did something simmilar, but according to him bore went up to 85mm on his 1.8 motor(this sounds a bit way too much for me though) and he uses a TDI crank, thereby making it roughlt a 2.1l motor. Its still being build, so i dont know if it will work when done.

I know on the 1.6i golf mk1 motors you have to change rods and crank only and you effectivley made a 1.8i motor.This stands to be corrected.

Hope this helps
Cheerz
2.0i ADY. 90.2kW & 198.1Nm atw excl. 40Horses VAT 13.9980sec @ OKH nationals 7/4/2012

User avatar
Smok3X
VWCSA Member
Posts: 2021
Joined: Mon Mar 02, 2009 10:04 am
Car Make: SEAT
Car Model: LEON CUPRA 2.0 TFSi K04
Membership No: 3083
Location: JHB
Contact:

Re: Bottom-End build ?

Postby Smok3X » Mon Nov 30, 2009 2:18 pm

Sorry if this sounds a bit dumb, maybe I am wrong... But wouldnt it be better to just buy a 2e or ADY 2.0l Long Block SUB and bolt on to your existing head? The Long block has a better rod angle ratio or something ? Some with a semi-forged crank, and you wont have to change or machine anything and start compromising reliability, and you could sell the 1.8 block you have... Probably wont cost you that much in the end :driving: Just my 2 cents...
Current:
Leon CUPRA - 2.0TFSi K04--> Rides Thread
[email protected] Artz - Stock
[email protected] Artz - RevO 2+

Ex:
Ibiza CUPRA - 1.8 20V - Hybrid Turbo-->Rides Thread
Revo:182KW and [email protected]
ABF Citi Golf - 2.0L 16V--->Rides Thread
FRC - 124KW and [email protected] Trix
1/4 Mile:14.61s
1ST Place - 4AF2 Margate 31st Oct 2010

ImageImageImage

User avatar
Solo786
Autowerks
Posts: 6781
Joined: Wed Feb 28, 2007 6:23 pm
Car Make: Porsche,BMW,VW
Membership No: 1251
Location: Umgeni Road...
Contact:

Re: Bottom-End build ?

Postby Solo786 » Mon Nov 30, 2009 2:33 pm

2e has a better rod ratio for turbo applications..

i'd prefer a shortblock 2.0 as it revs better because the rods are shorter

Maximum safe bore size imho would be 84mm

to build a 2.1 litre you'd need 83.5mm pistons and a tdi crank 95.5mm stroke, this will only work with a longblock, 2e, ady, aba
MERCEDES|BMW|PORSCHE|AUDI|VW|FORD
[email protected]
0847804447
Respect my AuthoriTaah!
Check out Autowerks on Fb
Check out AutoSpa on Fb

User avatar
panic-mechanic
Panic's Place
Posts: 23910
Joined: Mon Jul 29, 2002 9:08 am
Membership No: 79
Location: Benoni, putfontein.
Contact:

Re: Bottom-End build ?

Postby panic-mechanic » Mon Nov 30, 2009 5:57 pm

Wit ark - yes you stand to be corrected - absolute max bore is 84.5 and even that is a stretch. 84 is normally considered max due to the lack of area left between the pistons.
All the shortblock engines use the same conrods and to make and 1800 form a 1600 you change the crank and pistons. The rods remain.
As for the 2l shortblock revving better than the longblock - After many years of building several version of both I'm still not convinced the shortblock is better in any way. But each to his own. yes the theory that because the internals are lighter it should spin up faster is correct but other factors come into play when you look at rod ratios.
Stephan van Tonder - Jhb - Putfontein Benoni
'07 Audi S6 V10 - beast !!!!!
'05 Audi A6 3.0L TDI Avant
'07 Audi A4 2l TDI
'95 Audi 90 coupe quattro
'13 VW CC 2l tdi (repair project)
'05 Touareg v10

Perfect Power dealer. I do dyno tuning.

shannon ekermans
Cadet
Posts: 523
Joined: Sat Feb 02, 2008 1:24 am
Location: cape town
Contact:

Re: Bottom-End build ?

Postby shannon ekermans » Tue Dec 01, 2009 12:21 am

how far are you looking to go with this as you say its a drag car? cause 10-1 comp will get you so far but higher will help. 12.5-1 with racing fuel is a good start as well as knife edging blue printing and head work. lots of it. if this is more of a weekend fun/drag car then i say go with the kombi 2.6 pistons and the work as macman said but if oyur looking to be above most then its going to cost.
golf 94 cti
105kw

SHROSS
Wheel Whore
Posts: 31
Joined: Sun Jun 14, 2009 11:59 am
Contact:

Re: Bottom-End build ?

Postby SHROSS » Tue Dec 01, 2009 7:41 pm

Thanks for the advise ! Im very handy ! I like doing as much as I can ! Ive done a couple of heads , even build myself a flow bench !!! Im learning as I go on ! the motor thats in at the moment is a bog std 1800 bottom end with a head that I worked ! and it goes pretty well ! The 2l cranck I have is already Knife-edged !(did it myself)

I want to re-do another head , as Ive leart over the years where i went wrong the first time ! And build a perfect (worked) bottom end with near to max capacity !

The car is still street legal as I have to drive it to events ! So I dont want the comp. ratio too hectic !

I would like to run in the 14s easily , with this set up ! Im almost there with my current set up !

User avatar
panic-mechanic
Panic's Place
Posts: 23910
Joined: Mon Jul 29, 2002 9:08 am
Membership No: 79
Location: Benoni, putfontein.
Contact:

Re: Bottom-End build ?

Postby panic-mechanic » Tue Dec 01, 2009 8:19 pm

Just remember that at max bore - if something goes wrong you throw the block away.

Don't understand the latest fascination again with 'knife edged crank'. Seems every 2nd thread with a modded or hopefully modded motor has that. Have any of you actually had the crank indexed after doing work on it?. I have seen MANY bent cranks after guys done knife edging. VW cranks especially. By the way - have you ever done just that and seen what the power increase really is - if ANY. Knife edging normally only have a very small (1HP or so) benefit in motors that you rev to around 10000 RPM. This is the one thing where the effort and chance of ruining a good crank FAR outweighs the possible gain.
Stephan van Tonder - Jhb - Putfontein Benoni
'07 Audi S6 V10 - beast !!!!!
'05 Audi A6 3.0L TDI Avant
'07 Audi A4 2l TDI
'95 Audi 90 coupe quattro
'13 VW CC 2l tdi (repair project)
'05 Touareg v10

Perfect Power dealer. I do dyno tuning.

SHROSS
Wheel Whore
Posts: 31
Joined: Sun Jun 14, 2009 11:59 am
Contact:

Re: Bottom-End build ?

Postby SHROSS » Thu Dec 03, 2009 7:29 pm

Ja ! There are a couple of benefits that Im after with the Knife edged crank ! First thing it doesnt chuck the oil out the sump as much , keeping a health supply . It decreases rotational mass substantially wich promotes faster acceleration (not too worried about momentum).

But JA ! there is always a risk when working on critical components such as cranks and stuff !

Ive also sorced two spare 1800 (HV) blocks for when something goes sour !

User avatar
panic-mechanic
Panic's Place
Posts: 23910
Joined: Mon Jul 29, 2002 9:08 am
Membership No: 79
Location: Benoni, putfontein.
Contact:

Re: Bottom-End build ?

Postby panic-mechanic » Thu Dec 03, 2009 9:15 pm

uhm - if your crank is hitting oil up from the sump you are seriously overfilling your engine. You can just use a splash tray to minimise that in any case. As for making it lighter - did you weigh it before and after?. I'd rather run a very light flywheel than mutilate a crank.
It's not that I'm saying there isn't advantages - it's just that I have found that VW cranks don't like to be machined on the webs and there are other ways of trying to achieve similar results. Sadly these things come from school fees I have paid while preparing race engines for myself. There are some very fancy cranks - like oettinger and eurospec that are knife edged or reduced on the journal but they come out the factory like that and the webs are worked before the journals are machined.
If you ever have unexplained running bearings with funny wear patterns you know what caused it... Fix it by having the crank correctly indexed and cut to an undersize - which also makes it lighter :wink:
Stephan van Tonder - Jhb - Putfontein Benoni
'07 Audi S6 V10 - beast !!!!!
'05 Audi A6 3.0L TDI Avant
'07 Audi A4 2l TDI
'95 Audi 90 coupe quattro
'13 VW CC 2l tdi (repair project)
'05 Touareg v10

Perfect Power dealer. I do dyno tuning.

User avatar
geoffstep
Cadet
Posts: 296
Joined: Tue Oct 30, 2007 10:43 pm
Location: East London
Contact:

Re: Bottom-End build ?

Postby geoffstep » Thu Dec 03, 2009 10:51 pm

I have heard that there is a weight ratio or something like that with cranks...
Basically your webs on your crank are in perfect ratio to the weight of your conrod and piston weights...
If you knife edge your crank, by cutting your webs, it puts the ratio ot, and un-ballances your motor.
Anyone heard of this?
Sounds plausable to me...

Needless to say, I dont knife edge the cranks in my racing motors!
Image

User avatar
Solo786
Autowerks
Posts: 6781
Joined: Wed Feb 28, 2007 6:23 pm
Car Make: Porsche,BMW,VW
Membership No: 1251
Location: Umgeni Road...
Contact:

Re: Bottom-End build ?

Postby Solo786 » Fri Dec 04, 2009 10:06 am

Been there, ran the bearings, got the t-shirt.

when i rebuilt my motor the second time round i lightened the flywheel and installed an oil windage tray!!

school fees!!
MERCEDES|BMW|PORSCHE|AUDI|VW|FORD
[email protected]
0847804447
Respect my AuthoriTaah!
Check out Autowerks on Fb
Check out AutoSpa on Fb

BlueBlob
Panic's Place
Posts: 4654
Joined: Sat Jul 27, 2002 5:56 pm
Location: JHB
Contact:

Re: Bottom-End build ?

Postby BlueBlob » Fri Dec 04, 2009 10:20 am

geoffstep wrote:I have heard that there is a weight ratio or something like that with cranks...
Basically your webs on your crank are in perfect ratio to the weight of your conrod and piston weights...
If you knife edge your crank, by cutting your webs, it puts the ratio ot, and un-ballances your motor.
Anyone heard of this?
Sounds plausable to me...

Needless to say, I dont knife edge the cranks in my racing motors!



In a nutshell, yes. Those counterweights are there for a very specific reason; to balance the weight of the rod and piston (that weigh like 10kg when they turn at the top).

Cutting them off is a bit silly, and will definitely lead to funny wear on the bearings.

On a race motor that gets rebuilt every 100km it's one thing, but on a street motor you're just making trouble for yourself.

And you're doing it for maybe 1hp.

User avatar
pluto
Lieutenant
Posts: 1650
Joined: Mon Sep 08, 2003 7:53 am
Contact:

Re: Bottom-End build ?

Postby pluto » Fri Dec 04, 2009 1:48 pm

panic-mechanic wrote:uhm - if your crank is hitting oil up from the sump you are seriously overfilling your engine. You can just use a splash tray to minimise that in any case. As for making it lighter - did you weigh it before and after?. I'd rather run a very light flywheel than mutilate a crank.
It's not that I'm saying there isn't advantages - it's just that I have found that VW cranks don't like to be machined on the webs and there are other ways of trying to achieve similar results. Sadly these things come from school fees I have paid while preparing race engines for myself. There are some very fancy cranks - like oettinger and eurospec that are knife edged or reduced on the journal but they come out the factory like that and the webs are worked before the journals are machined.
If you ever have unexplained running bearings with funny wear patterns you know what caused it... Fix it by having the crank correctly indexed and cut to an undersize - which also makes it lighter :wink:


Agree with Panic .. Windage tray for the sump is R400 , keeps the oil in the right places..
Shiver me Wastegates

Frieling Racing Chip tuning

[email protected]
082 805 9060
2013 TT-RS S Tronic
MK1 20VT BAM (Motronic ME 7.5 DBW)

shannon ekermans
Cadet
Posts: 523
Joined: Sat Feb 02, 2008 1:24 am
Location: cape town
Contact:

Re: Bottom-End build ?

Postby shannon ekermans » Fri Dec 04, 2009 3:34 pm

just for interest sace the 2.0 build with the combi 2.6 pistons give you a comp of around 9.35-1

here is why.
head cc =31.5 on a mp9
bore =82.5
stroke =92.8
head gasket diameter=83.5
crushed head gasket thickness=1.55mm
piston top cc=20
height above deck =0
total comp =9.35
its because the cc in the piston is twice that of the stock 1.8 dish
golf 94 cti

105kw

BlueBlob
Panic's Place
Posts: 4654
Joined: Sat Jul 27, 2002 5:56 pm
Location: JHB
Contact:

Re: Bottom-End build ?

Postby BlueBlob » Fri Dec 04, 2009 3:40 pm

shannon ekermans wrote:piston top cc=20


How sure are you about that one? When I measured it on my turbo motor, with the cut-outs for the valves, they were only about 13cc?

shannon ekermans
Cadet
Posts: 523
Joined: Sat Feb 02, 2008 1:24 am
Location: cape town
Contact:

Re: Bottom-End build ?

Postby shannon ekermans » Fri Dec 04, 2009 4:17 pm

well thats what i got the first time i did it myself but then i was using a syringe. so i had a guy do it in a ring squeezer with a pipet and he got 20cc. it does seem very high doesnt it. i think i must do it again myself with a pipet and try it again.
golf 94 cti

105kw

SHROSS
Wheel Whore
Posts: 31
Joined: Sun Jun 14, 2009 11:59 am
Contact:

Re: Bottom-End build ?

Postby SHROSS » Fri Dec 04, 2009 5:57 pm

Thanks Guys ! This is all really good to hear before I go and stuff-up my motor ! The motor I need , is strictly 1/4 mile ! Already started with a A-frame for next years events !

That comp. ratio is a bit low !!! How would I go on making it closer to 10.5:1 ? You also quoted it useing a mp9 head ! Is there any difference to a 1800 carb head ?

User avatar
panic-mechanic
Panic's Place
Posts: 23910
Joined: Mon Jul 29, 2002 9:08 am
Membership No: 79
Location: Benoni, putfontein.
Contact:

Re: Bottom-End build ?

Postby panic-mechanic » Fri Dec 04, 2009 6:42 pm

Yes you are perfectly right. We normally deck the block so that the piston squish pad comes above block level. About 0.8 mm of pad sticking out normally does the trick.
Stephan van Tonder - Jhb - Putfontein Benoni
'07 Audi S6 V10 - beast !!!!!
'05 Audi A6 3.0L TDI Avant
'07 Audi A4 2l TDI
'95 Audi 90 coupe quattro
'13 VW CC 2l tdi (repair project)
'05 Touareg v10

Perfect Power dealer. I do dyno tuning.

shannon ekermans
Cadet
Posts: 523
Joined: Sat Feb 02, 2008 1:24 am
Location: cape town
Contact:

Re: Bottom-End build ?

Postby shannon ekermans » Fri Dec 04, 2009 9:48 pm

the mp9 head has dished valves so they have .9cc more combustion volume but your best bet is to cc them exactly as your head may have been skimmed etc etc.
golf 94 cti

105kw

Return to “General Tech Discussions”

Who is online

Users browsing this forum: Bing [Bot] and 71 guests