reducing capacity of 1.8T

RobT

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Nov 30, 2001
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yes really - reducing the capacity to say 1.4 L

why ?

for racing. I run in up-to 2000cc class and need more power. Found out at the weekend that the class record holder, a BMW 2002 , is a 1.4 turbo running lots of power. You are allowed to run a turbo but the capacity multiplier is 1.4 hence 1400 turbo would be allowed in the up to 2000cc class.

What are the restrictions ? it needs to have a block, or derivative of, that was fitted to some model of the car you run, i.e as fitted to Mk2 ibiza.

If 500hp is possible from a 1900 20VT, then 370-400 should be possible from a 1.4 - not worth doing for less than 400hp

Issues - the block must be able to accept an 02a-type box

If a 1.8T block was used, stroke would have to reduced to 67.91mm (from 86.4) if using the 81mm pistons

If keeping the stock block height (as I dont know what I can be reduced by), rod would have to be lengthened by 18.49mm to 162.49mm.

This would give a rather large rod ratio of 2.39 (stock is 1.66) - some endurance engines are 2.2 but 2.4 might be a bit too much......

If this is too much, a different block would have to be used - but this block has to accept a 02a box and be fitted to an ibiza originally and be a 16V

Of interest is some specs of an engine from a Toleman Hart 184 - this was a 1.45L turbo that made 650hp @ 10.5K back in 1984. This was with a 88mm bore and 61.5mm stroke - not a million miles off a desroked 1.8T............

would love to hear what folks think about this (crackpot?) idea

Ave it

Rob
 

WeeJase

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Jun 2, 2001
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so in theory you could run a 1.4 8v/16v engine and just turbo that ?wouldn't starting with 1.4 be easier rob?Or am i missing the point?
 

RobT

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the mk2 ibiza does come fitted with a 1.4 but i'm not sure if a 020 or 02a can be bolted up to it.

Also - it needs to have a good cylinder head for lots of flow - dont know if the mk2 came with a 1.4 16v that will take the 020/02a - anyone know ?

And even if the above does exist - will be be strong enough to take 400hp ? a 1.8T would if it could be configured right and loads of external bits are available off the shelf to do it (manifolds etc)
 

WeeJase

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Jun 2, 2001
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how you going to get around running a 1.8/1.4 20vt in a mk2 though rob?it was never fitted to the mk2.
i take it turbo'ing yours takes you up a class then?
 

RobT

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put the 20v head on a adl block - only block has to be std, head is free - plenty people done this in US to make 2L 20V's using abf or 9A or aba-type bloaks

or just use the adl as a base - 16V head would work and there are plenty of turbo mani's out there for this although would probably make one - may consider turbo'ing through dth tb's like folks used to do with dhla dellorto's

I cannot turbo mine as it would move me into 3c, over 2L, which (a) is not allowed as your not allowed to run a car in a capacity class that it was never in as a standard car and (b) it would put me up against evo's - dead meat !
 
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m0rk

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May 19, 2001
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technically in the eyes of SEAT the mk3 ibiza was actually a mk2 'facelift' - so any of the engines in the 6K shell are fair game

the 1.4's use the 085 gearbox, which is a) **** b) not the same pattern

What was the carbon bodied elise 1.4T at curborough years ago, that thing was bloody lightening
 

RobT

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hmm - if the 1.4's use the crap box then it wont take the power - so using the 1.4 block is out.

It would have to be using a big block 1.8 or 2.0 liter based.

Here's a few more thoughts to throw into the mix:

Nissan did a reduced capacity engine called the SR16VE for Japanese market only - a high revving derivative of the SR20VE. The 2L was 86mm bore and 86mm stroke with a 136mm rod. With the 1600, they reduced the stroke to 68.7mm, same bore, and fitted a 145mm rod. Rod ratio = 2.11. This is widely regarded as a cracking engine, 200hp from 1600cc, revs to the moon.

Not a million miles away from turing a 1.8 20VT from 81mm bore, 86.4mm stroke, 144mm rod to a 1.4 20VT with 81mm bore, 67mm stroke, 162mm rod. Rod ratio = 2.39.

I was concerned about the idea of too long a rod but it seems this isn't especially an issue - F1 engines have rod ratios as high as 2.8 and strokes that are 50% of bore sizes.

I reckon a 1.4 20VT would rock big time - rev to the moon - and a lot of the inlet and outlet gubbins is off the shelf. Would need some rods and a crank making, pistons off the shelf as same as 1.8 20VT stuff. Would need to be solid lifter for the revs - over 10K would be on the cards methinks. with a turbo......cummon

That elise was a K series 1.4 turbo and also ran in upto 2L modprod - like you said, it rocks, think it still holds some class records. The aintree record is a BMW 2002 touring with a 1.4T - 4 seconds faster than I am managing to go with my motor, which is no slouch for a 2L atmo lump
 
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Fl@pper

Back older greyer and less oilier but always hope
Jun 19, 2001
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wouldn't a longer throw crank allow enough for you to run shorter rods ?

never seen one in a block to see what clearance there is though or not as the case may be

plus any of the possibles come aluminum blocked ? 1.4 AKK ?
 

RobT

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Longer stroke crank will up the cc bud.

Maybe there are some other block possibilities - latest 1.4 TFSI engines with turbo/supercharger - 1390cc, 10:1 CR (on a turbo !), 76.5mm bore and 75.6mm stroke

if this block can be described as a derivative of that fitted to a Mk2/3 ibiza, could be useful

and I think its the same bolt pattern as its fitted with the 02s box which is same as O2a/j.
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
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Longer stroke crank will up the cc bud.

Maybe there are some other block possibilities - latest 1.4 TFSI engines with turbo/supercharger - 1390cc, 10:1 CR (on a turbo !), 76.5mm bore and 75.6mm stroke

if this block can be described as a derivative of that fitted to a Mk2/3 ibiza, could be useful

and I think its the same bolt pattern as its fitted with the 02s box which is same as O2a/j.

that is the one I was goign to suggest you investigate Rob
 
Do you have to run a turbocharger inlet restrictor at all?? if so, you need a totally different engine solution, but assuming you don't:

1) biggest bore possibly
2) shortest stroke (don't worry about rod length too much (see 3 below)
3) deck block as much as possible to get CR optimised and to reduce block weight (turbo intercooler etc are all heavy so base engine must be light
4) if you are allowed to run an adaptor plate between block and g/box, dry sump engine and spin gearbox round to allow drive shafts to be infront of block, running under inlet manifold as in old skool BTCC cars, then slam the engine onto the floor! lol
5) turbo size, ports and valve sizes / cams need to be set to trade off between response and ulrimate power potential
6) if you gonna rev it to 10k, an ultra light crank and reciprocating components will minimise block stresses, (rather than running low rpm and high bst to make power)
7) how std does the block have to remain?? i.e. take the old 1.4 16v motor from the polo / ibiza, machine out the block to accept liners, deck the block by as much as you can get away with

i would think that without an inlet restrictor, 8k rpm would get you a pretty genuine 300 ponies, and 10k maybe 370+
so with the appropriate gearing to utilise this rpm peaks, you would perhaps have a 60 % increase in tractive effort at the wheels compared to your current engine! (but maybe with a 20kg weight penalty, less if you wanna get flash with your componentry, ie. Cf parts etc)

The only disadvantage i can see with a destroked 1.8t is the weight penalty, which some smart design my offset to a degree, and you have the advantage that suitable robust top end parts are availible with proven durability in race applications etc
At the last time i asked, a one-off DKE steel crank was in the region of £1800 to £2200 depending on how much design you do yourself etc
 

RobT

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cheers bud, this is very useful.

I run in modified production so the only engine restrictions I have are that I must use a block that is externally identifiable as one originally fitted to the model of car - or 'derivative' thereof - as m0rk said above, I think you could argue that the M2 and Mk3 ibiza's are the same as both same 6K chassis - so a 1.8T block would be fair game. And it must run on pump fuel.

Using the 1.4 block would be good for weight but the bores are tiny and it wont take a strong gearbox without lots of work. And the 1.8T head will flow enough gas.

If using a destroked 1.8T, I could take advantage of all the excellent work Mr Brockbank et al have been doing on inlet / outlet and turbos.

I using good components, do you think such a setup could go to 10K ?
How do you determine how much a block can be decked by ?

400hp is what I was aiming at - to make it worth the effort. This may be doable by the sound of things especially if I use E85 as well.....

As mentioned, there was a chap called Mark Waldron who did rather well in the British Hillclimb Champs in a carbon bodied Elise with a turbo technics 1.4T K-series in it:

http://www.turbotechnics.com/docs/cars/waldron.htm
http://www.sandsmuseum.com/cars/elise/thecar/engine/kingk.html

300hp spinning to 8.5K with a stock crank (75mm bore / 79mm stroke - 1396T)
400hp was tried with a custom steel crank but it went bang on first outing as not balanced correctly

With 81mm bores and a 5 valve head.....this can be topped.
 
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RobT

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Hmm - just spoke to my engine man - he's done em before......400hp no problem at 10K when unrestricted. And he's already got a crank on the shelf.

I can feel my wallet groaning
 
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pj1985

1.8T Power
Oct 31, 2006
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What effect does all this have on the characteristics of the turbo delivery? Will it cause any lag issues? If you want to rev to 10k rpm then how does that go with say a k03 turbo that is out of puff by then or a bigger turbo that may not spool until quite alot later up the rpm?
 

RobT

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the turbo will be sized based on required powerband - the only way to make large power from a small engine is to rev it or boost it - possible gearing will have some effect on revs and the rest will be boost - unless some variable nozzle turbine can be used, its going to be a bit laggy I suspect but doing a lot of sums presently to see what might be possible

k03 will be way too small for required top end power but may spool up quite nice. Like you said, bigger turbo will be laggy and then deliver the goods. Need to find a compromise. Something like a T3/T4 hybrid may do the trick.

I dont really know that much about turbo's but started some reading last night and things are starting to make sense - can highly recommend book Forced Induction performance Tuning by Graham Bell.

Looks like for 400hp, exducer bore needs to be 60-70mm
Low A/R turbo's (eg 0.6) make power low down and run out of puff, large A/R opposite (eg 1.0)
Compressor size dependent on compressor maps for the turbo, staying inside efficient operating area, making sure you dont fall into surge
Worked out that CFM will be around 43-54 lb/min - need to see if this will make the power needed next

to be continued
 

ibizacupra

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Jul 25, 2001
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my FP green was a 49lb comp wheel off a GT30 turbo.. as a guide.
new management to run it Rob.

An idea of the VNT kind of appeals for balance of power delivery etc.. sprints being short events it may be ok heat wise.

GT28Rs/2871 kinda seem roughly the sort of size to look for...
as high a CR as you can accomodate with fuel grade and management to control it so its less reliant on 'da boost' to get going.

well interesting project.

those mani links are all log style, which is good for spool with less internal valume to fill, but not so good when high flows are asked as opposing ports shoot at each other, killing top end flow.
 

RobT

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my FP green was a 49lb comp wheel off a GT30 turbo.. as a guide.
new management to run it Rob.

An idea of the VNT kind of appeals for balance of power delivery etc.. sprints being short events it may be ok heat wise.

GT28Rs/2871 kinda seem roughly the sort of size to look for...
as high a CR as you can accomodate with fuel grade and management to control it so its less reliant on 'da boost' to get going.

well interesting project.

those mani links are all log style, which is good for spool with less internal valume to fill, but not so good when high flows are asked as opposing ports shoot at each other, killing top end flow.

cheers for chat - as you know, was thinking of new management anyhow so may as well be for this, switchable maps is the future :funk: E85 here we come

will have a look about some more tonight - only 16V mani's I could find were those log ones but will keep looking - maybe one of your tubular ones with a 16V head flange may do the trick