88mm Overbore

[mos 1]

hi,

 

i am still plotting and planning my s16 engine rebuild

i have two engines in pieces i acquired from a guy over on the psooc forum.

my original intention was to overbore to 88mm with pistons from qep/hi flow etc and a 1.9 crank of some description giving a square 88mm by 88mm.

but i have done some further research on this over the weekend and it seems there may well be problems doing this conversion.

to be honest i have got square eyes i have been at the computer that much on here and the psooc forum over the weekend!

in fact i have been on here that much that my girlfriend is threatening to walk out!

when she finds out how much my new engine is likely to end up costing i think she might actually do it!

All kidding aside

i am now seriously worried that the 2.0ltr block with not take the overbore because it will either breach the water jacket

or the block will crack across to the water jacket when in use,

or the block will become porous.

i have seen numerous post of people doing this conversion (such as anthony amongst others) over the past couple of years.

only problem is no one seems to have been back on with an update to say if it worked or not and if the conversion proved reliable.

i really could do with with people's thoughts/findings/experiences on this and if indeed 88mm bore is a bridge too far (or bore for that matter!)

if 88mm is a no no, are 87mm pistons 88mm crank worth the effort (for the minimal increase in cc over standard)

or are the performance gains worth the effort for a fast road engine with a gas flowed head, hotter cams and carbs.

 

oh, one last question, which rods do you use for the conversion the standard 2.0ltr ones or the 1.9ltr ones?

 

thanks

 

mark

Edited August 6, 2006 by mos

[petert 554]

I think you'll be more than impressed with an 87x88mm engine. You use the 2L rods.

[pug_ham 242 3 Cars]

Stew 205 is running an 88 x 88mm engine in his with aboslutely no problems so far & so is Maxi afaik.

 

If you are willing to spend the money go 88mm, if youare concerned about the water jacket breaching (iirc it has been mentioned by BlackMi16) then 87mm is still worth doing.

 

Graham.

[B1ack_Mi16 67]

Stew 205 is running an 88 x 88mm engine in his with aboslutely no problems so far & so is Maxi afaik.

 

If you are willing to spend the money go 88mm, if youare concerned about the water jacket breaching (iirc it has been mentioned by BlackMi16) then 87mm is still worth doing.

 

Graham.

 

I believe the blocks with oil squirters will take 88mm bore, also the XU11D blocks seem to be of the same casting and be able to handle 88mm bore.

 

I have both a bare T16/10J4TE and XU11D block and they seem to have equal thick cylinders, same as my XU10J4R (early model that still had squirters).

 

It would have been nice to see some close-up photos of a XU10J2 block or something to compare the casting to the 16v blocks.

 

Anyone got close-up pics of a non oil-squirters XU10 block then?

 

Edit: Added high-res picture of my block with 88mm bore.

http://cortex.fa-s.ntnu.no/~kristian/205gt...rs/88mmbore.jpg (1.5mb)

Edited August 7, 2006 by B1ack_Mi16

[mos 1]

the two blocks i have both have oil squirters so you guys think these should be ok for a rebore to 88mm but if i want to play it safe go 87mm.

 

there is a lot of talk on the forum about 2.1 diesel 92mm crank, would this be a better/worse option than an 88mm crank for a road going car, would the benefits of the extra displacement be cancelled out by loss of squareness to the bore/stroke ratio and am i into big bucks for custom rods to make this work.

 

i am currently on a steep learning curve with this overboring/different crank 2.0ltr 16v stuff and as eager as i am to get cracking on the project i just want to make sure i make the best/smartest choices i can before jumping into this.

 

thanks

 

mark

[petert 554]

At the end of the day, it all depends how deep your pockets are. Fitting an 88mm crank and boring to 87mm with forged pistons is relatively cheap, and you can use a standard head gasket.

 

 

88x88=2140cc

87x88=2092cc

[mos 1]

i guess what i am asking then is if cost was no object what would ultimately be the best bottom end for a road going car a 88x88, 88x92 or even 88x96mm, crank from a dw block (if it would fit)

would it be detrimental to move away from a truely square 88x88 to an undersquare bore/stroke ratio or would the extra cc result in much better torque/power (particular low down torque) that the sacrifce of losing a free reving 88x88mm square engine be worth while.

i am not an expert on the pros and cons of square engines vs undersquare/oversquare etc but as best i can tell this the squareness leads to a willingness to rev like the 1.6 gti over the undersquare 1.9gti.

is this correct or am i talking bol*ocks?!

what would the situation be regarding pistons etc. obviously i am going to have to source 88mm pistons from the likes of QEP or hiflow or some other engine builder etc but what rods would i need to keep the compression to a reasonable level, could i get away with using the s16 rods like i can with 88x88mm or am i into custom rods for either the 92 or 96mm cranks.

 

any ideas on the cost implications would be great as well

 

thanks

 

mark

[willxs 0]

also interested in this as its something im considering for the near future.

 

Keep me posted on how you get on please mos.

 

 

Cheers

[mfield 20]

Iirc the bore/stroke doesn't dictate the reviness of the engine, but more the flow of the head. A bloody good example is the difference between the 1.9 8v and the 1.9 16v. Both have the same bore/stroke but the 16v flows more air so the engine still makes power high in the revs.

 

The increase in displacement should lower the power band of the engine and give more torque, much like the effect of going from a 1.6 8v to the 1.9 8v.

 

I hope ive got that correct

 

 

 

i guess what i am asking then is if cost was no object what would ultimately be the best bottom end for a road going car a 88x88, 88x92 or even 88x96mm, crank from a dw block (if it would fit)

would it be detrimental to move away from a truely square 88x88 to an undersquare bore/stroke ratio or would the extra cc result in much better torque/power (particular low down torque) that the sacrifce of losing a free reving 88x88mm square engine be worth while.

i am not an expert on the pros and cons of square engines vs undersquare/oversquare etc but as best i can tell this the squareness leads to a willingness to rev like the 1.6 gti over the undersquare 1.9gti.

is this correct or am i talking bol*ocks?!

what would the situation be regarding pistons etc. obviously i am going to have to source 88mm pistons from the likes of QEP or hiflow or some other engine builder etc but what rods would i need to keep the compression to a reasonable level, could i get away with using the s16 rods like i can with 88x88mm or am i into custom rods for either the 92 or 96mm cranks.

 

any ideas on the cost implications would be great as well

 

thanks

 

mark

[StuF215 1 1 Cars]

Do you have to work the chambers in the head to 88mm? Does this give to much compression if you dont?

 

 

Stu

[B1ack_Mi16 67]

Do you have to work the chambers in the head to 88mm? Does this give to much compression if you dont?

Stu

 

Really depends what stroke you choose, and the camshafts.

 

No need to rework the chambers, but I believe it's a good idea to unschroud the valves a little bit at least.

[kutija 1 1 Cars]

Hi.

Do you use torque plate when boring the XU10 block?

My block from xu10j4te is waiting to be bored to 86.5mm so I just want to know if it is necessary to use torque plate...

 

I'm gonna use standard 86mm crank as I don't need any more torque

 

btw. also need your opinions on JE pistons???

[petert 554]

Do you use torque plate when boring the XU10 block?

 

It depends on what type of job you want. A case of getting what you pay for.

[kutija 1 1 Cars]

Ok.

So you would recommend using a torque plate,right?

[B1ack_Mi16 67]

Ok.

So you would recommend using a torque plate,right?

 

Of course, that was what he indirectly wrote....

[mos 1]

hi,

 

just like to thank everyone for there help with this.

i have received a few pm from a couple of people who have experience of this or are actually running 88mm bore in there cars. given me the confidence that it does actaully work and 88mm is possible.

 

i have decided i am going to go for it and do the 88mmx88mm block.

 

this will then be mated to a gas flowed head and cams etc although i have still do decide on the spec of the head and cams etc i or whether to go down the big valves route or not.

i will be running my 45 dellortos with this and a mapped ignition system. aiming for over 200bhp and 160lbs of torque, not bad for a road going car.

i would like to eventually move over to a fully integrated fuel/ignition management system using throttle bodies put with what this engine conversion is likely to cost that will definately have to wait a while!!!

 

i will update this thread at regular intervals to keep anyone who is interested in the picture of where i am upt to and how things turn out. no doubt like most projects like this it will be a bit of a rocky ride!

 

i am just wondering which manufacturer of pistons you guys would recommend and who supplies them, cost etc...

i want to start assembling all the bits and pieces i need asap

 

thanks

 

mark

Edited August 11, 2006 by mos

[smckeown 1]

carbs or tbs for a road going 15 year old car. that's not for me

[mos 1]

thats fair enough, each to his own and all that

 

my three previous cars were all modern vehicles, an audi tt roadster 225 and then a 3.2 and a honda civic type R

the tt was too refined no character did everything you asked with no fuss, but equally no fun! and always in the dealer for minor niggles (so much for the fable german engineering!)

the honda was gutless around town, you had to rev the tits of it to get it to feel anthing other than a standard 1.4 etc...

i often remarked its like a boy racer nova, crap interior (by modern standards) rock hard suspension and i do mean rock hard! felt like some kid had just put 60mm lowering springs on with no though for our crap roads. no performance in real around town driving, complete lack of decent low down torque. plus the gear stick postioning made you feel like you were sat in a people carrier! particularly glad to see the back of that one

hence back to my roots back to doing what most of the general public would call "a silly waste of money on a old banger"

but my 205 puts a smile on my face which is more than my three previous new cars did and even if i end up "wasting!" 5-6k on modifying a 205 its probably on a par with the deprication on a new or nearly new car over a year or two! and its not like i go on any long motorway journeys anymore!

 

but i am suprised i am having my judgement question on modifying a 205 gti on this forum!

i thought that was one of the driving factor of the forum?!

Edited August 11, 2006 by mos

[petert 554]

i will be running my 45 dellortos with this and a mapped ignition system.

 

I still can't believe anyone would consider running carbs on an S16, unless maybe you had them sitting on the shelf doing nothing. Even then, I'd stick them on eBay and buy TB's. The S16 has both crank and cam sensors, allowing you to run full sequential injection and direct fire ignition. Forget the big valves and buy an ECU that has four injector outputs and four ignition outputs. You'll end with a far more user friendly product.

Edited August 12, 2006 by petert

[huxley309 0]

but i am suprised i am having my judgement question on modifying a 205 gti on this forum!

i thought that was one of the driving factor of the forum?!

 

I think it's more to do with them not being able to justify such cost let alone afford it, ive gone and spent lord knows how much on this 309 and i say go for it you wont regret it, my cars immense fun i always look forward to giving her a good ragging

 

As for je pistons.....lots on here will slate them...poor machining etc but i have their 85mm forged jobbies in my car and they've done exactly what i set them out to do

 

if you plan to move over to bodies eventually why not just go for a std s16 with bodes for now that was you'll have extra poke and less hassles having to remove the carbs

[Super Josh 4]

carbs or tbs for a road going 15 year old car. that's not for me

 

 

Sean, why would you not fit TBs on a road car? Interested in your input, seeing as you run them.

 

 

 

 

Josh

[mos 1]

I still can't believe anyone would consider running carbs on an S16, unless maybe you had them sitting on the shelf doing nothing. Even then, I'd stick them on eBay and buy TB's. The S16 has both crank and cam sensors, allowing you to run full sequential injection and direct fire ignition. Forget the big valves and buy an ECU that has four injector outputs and four ignition outputs. You'll end with a far more user friendly product.

 

 

thats exactely why in the first instance i am planning on running carbs, i have them already hence no cost except for a new inlet manifold which i will need anyway if i went down the throttle body route, so that cost kind of cancels itself out.

ther is no way i would go out these days and spend £1,000 maybe more on carbs when you can source throttle bodies etc from as little as £1,400 through QEP for the KMS stuff then of course there is the remapping etc on top bringing the true cost to nearer £2,000.

your right though i probably could offset a good portion of that cost by selling by carbs,fuel pump, throttle linkage, manifold etc... i would imagine that little lot may fetch somewhere around £500

i do actually want to go to throttle bodies and i think your dead right perhaps i should spend my money on these rather than Big valves etc.

i actually have started a thread on throttle bodies vs carbs last night from a fuel economy standpoint to try and justify it to myself. but to be honest i need to do my homework on the various systems out there and a good tuner/mapper. the KMS stuff looks decent value but i do not know if it is any good or what the options are at this time.

whatever happens the 88mm bottom end is still on as everything i have from the two engines is in pieces in my shed!

 

thanks

 

mark

[mos 1]

dropped all my engine bits and pieces etc with Matt at QEP yesterday as he will be building the engine.

i gave him a scrap block to try the 88mm overbore on first to see if it breaches the water jacket.

hopefully it wont and i will have a 88mm/88mm bore/stroke if not the bore will have to be 87mm.

hopefully the engine will be ready by mid october but i am away for a week then so will not be able to start install till late october.

 

the engine will be running kms engine management/throttle bodies so should go pretty well i hope!

[Henry 1.9GTi 36]

bit late but may be worth considering, if u bore to 88mm and something goes wrong a few years down the line which requires a rebore u cant do it with 87 u have to the option to go a bit bigger. Or just buy a new block and bore that, suppose their quite cheap?

 

so is the s16 block not a wet liner design?

also r the s16 con-rods up to the same job as 1.9Mi con-rods, are they same standard basically? With the increased stroke does this mean the pistons sit above the block? So would need heavy machining on pistons for vlave clearence? What affect does having the piston sit higher at TDC have on performance? Is the 1.9Mi head still used? Also with the extra bore can the inlet valves be made even bigger than the 36.5mm ones puma makes, would this have a negative affect on performance rather than a positive? i.e low down in the rev range..

 

sorry so many q's just very interested as i would love a 2.1L in the 205

 

also whats the extra weight of this engine as it is off putting having more weight in the front.

 

enlighten me, as i dont know much but this stuff, although after my engineering course it should hopefully be a little clearer!