Xu9 8v Displacement Options

[bales 1]

I have had a bit of a search for this but not found too much, what are the different configurations you can use to increase the capacity on the 8v engine.

 

I have read lots of posts on the mi16 and all the different cranks and bores etc...that can be used to get 2088cc and up to 2300cc almost but not much about the 8v engine.

 

I have upto know been thinking of doing the turbo conversion but had a chat with a my local engine builder tonight who is very well respected round here and am considering all options again as I may want to hillclimb my car hence keep the xu9.

 

Are the use of diesel cranks and the like possible and an 88mm or 86mm bore rather than 83mm, what options are there in this area?

 

Cheers for your help.

 

Alex

Edited January 10, 2007 by bales

[pug_ham 243 3 Cars]

The only way to increase the capacity on the alloy XU9 is by getting over bored liners & pistons to suit imo.

 

Not particularly cheap to do, more of the topics on here are probably discussing using the XU10 block which is already 86mm bore which with the crank from the 1.9 will give 2044cc, boring this block out to 88mm will give 2144cc.

 

Graham.

[smckeown 1]

83.5mm forged pistons and liners is the only cost effective way I know of. Gives 1926cc. Cost is circa £600 which isnt bad if you were needing new units anyway

[Sandy 191]

No reason why you can't build an iron bottom end with larger bore, the 306 engine mount would enable you to use a skimmed down 405 SRi head, which with some minor work is IMO a better bet than the XU9JA or XU10 heads.

[B1ack_Mi16 67]

83.5mm forged pistons and liners is the only cost effective way I know of. Gives 1926cc. Cost is circa £600 which isnt bad if you were needing new units anyway

 

I really don't think it's a problem putting a 92mm crank in the 1.9 8v either.

And 85mm liners exist, with some custom 85mm pistons you might be able to keep the standard rods, althgouh Mi16 rods is preferable as tehy are already bushed in the small end to accept floating pins.

 

92 x 85 = 2088cc.

 

Going to cost quite a bit.

 

Easier to go eq. 87mm bore on an iron block and still keep 92mm stroke which will give 2187cc.

Or go 88mm bore and use the 96mm crank from the 2.2 EW engine, 2335cc.

 

The 96mm crank with 87mm bore gives 2282cc.

 

All just depends on how much money you are willing to spend.

 

I got new custom rods and pistons anyway on my build, so didn't really matter what crank or bore I did choose.

 

Guess you could use the 96mm EW crank in the XU9 also, 96 x 85 gives 2179cc's from the alloyblock.

But it's a bit shorter so you will get Rod / Stroke ratios on the low side.

[James_R 3]

Like sandy says, if you are considering building it for competition can use a Diesel block

 

but you'd be in a mega engine sized class as most forced induction engines get a 1/4x relative cc increase.

[Sandy 191]

85mm liners aren't reliable in my experience, on engines with 88mm stroke. using them with even greater stroke is asking for trouble I would say.

[B1ack_Mi16 67]

85mm liners aren't reliable in my experience, on engines with 88mm stroke. using them with even greater stroke is asking for trouble I would say.

 

I thought Miles was running 86mm liners on their race engines, so 85mm liners of correct material should be more safe than that I believe.

 

My enginebuilder di at least bore normal Mi16 liners to 84mm once, and put Mercedes pistons in it, and used some BMW rods and offsetground the crank to 89mm stroke.

 

That worked realible.

[Sandy 191]

Of the two that i'm personally aware of, one was built by a well known company with what are regarded to be high quality liners and lasted 7000 miles on the road before losing compression in a big way and the other was built by a very reputable race engine builder that advised the customer against using the liners, but the customer was insistant. It made 270bhp on the dyno and after one event lost compression. Two of the liners (again "high" quality liners) had cracked near the seats it transpired. That engine is being re-built into an Iron block, the 18kg penalty will easily be worth it for reliability.

[niklas 1]

I'm using 84mm bored liners on my MI. Standard stroke 88mm.

Will be interresting to see how long it lasts.

The guy who bored them advised against it, and they do look thin on the part that goes down in the block.

[B1ack_Mi16 67]

Of the two that i'm personally aware of, one was built by a well known company with what are regarded to be high quality liners and lasted 7000 miles on the road before losing compression in a big way and the other was built by a very reputable race engine builder that advised the customer against using the liners, but the customer was insistant. It made 270bhp on the dyno and after one event lost compression. Two of the liners (again "high" quality liners) had cracked near the seats it transpired. That engine is being re-built into an Iron block, the 18kg penalty will easily be worth it for reliability.

 

Ok, get the point now, thought they would be more realible than that really.

Iron block is the way then

 

People seem to think there are difference between iron blocks too though, I have found the XU11D block to have same cylinderwall thicknesses as the GTi6 block and T16 block.

 

Maybe lesser 8v blocks really are thinner, I've never seen one, but heard lots of stories about people boring 89mm and getting into the water jacket.

 

About the liners, what about getting the liners machined from billet and make them 1 big chunk of metal, and not 4 independent ones, that might be more solid, and you could increase the bore and still have lotsa thickness between the bores. Ain't Hondas made that way?

Edited January 11, 2007 by B1ack_Mi16

[Sandy 191]

The expense of making a bespoke single liner unit would be bonkers, it's only the economies of scale that enable manufacturers to do it. Most Honda engine overbores (e.g. the good ones) seem to use ferrous liners sleeved into the alloy liner casting. Personally I think you lose most of the advantage of a Honda engine by modifying it internally, they are so well made.

 

There are two types of Diesel 83mm block available, one has slots between the bores and isn't much use, but the other is solid decked and can bored as extensively as the XU10 block. There's no consistent pattern to which cars have them though!

Edited January 11, 2007 by sandy309

[bales 1]

Thanks for the replies so far, I think by the sound of it that to use the xu9 it is going to be quite a bit of work and not cheap to increase the displacement by a significant amount. I know that capacity isnt necessarily going to achieve large gains as has been discussed a lot on this forum. But I was really wondering whether there were any straightforward changes with cranks or different bores, but it sounds like there isnt really.

 

The guy I have been speaking to isn't really massively heard of in the peugeot tuners infact he has only done a few, however he did an 8v the other month for a rally car that was a 1900gti and it got dynoed at 180bhp (not rolling road) so I have faith that he knows his stuff. He tends to specialise in cosworths especially N/A Yb engines so I am confident that he is good.

 

I was watching seans video's off his site last night again and it really does sound fantastic (I would be going throttle bodies and ecu), I think it is very easy to get carried away in the whole power things especially with turbo's as 220+bhp is always bandied about, but I have a feeling that I would get a turbo engine then be dissapointed that it just wheelsapn everywhere and I would be probably slower on normal roads waiting for a straight until I could put my foot down.