ned
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| posted on 28/5/03 at 12:28 PM |
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Resleeve or Rebore?
Hi all,
I finally got the chance to strip my (vx 16v) engine down last night (well as far as the block anyway) to find IMO considerable wear on the bores.
The lip at the top of the cylinder is quite substantial, the sort you can catch your nail on (and almost certanly would catch a piston ring if the
piston went skywards).
From my understanding I can either have it honed out/rebored and fit oversize pistons or resleeve the cylinders back to standard (I know someone who
did this @ cost of £300)
Can anyone tell me how much a rebore + set of oversize pistons will cost? (ball park figure?)
I'm also considering racing with this engine at some point in the future, so I presume resleeving will be best for this incase regulations
don't allow oversize engines/rebores.
Ned.
beware, I've got yellow skin
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paulf
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| posted on 28/5/03 at 08:53 PM |
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As you know sleeving is very expensive as it involves boring and then sleeving and boring again to size, you would still need to buy pistons anyway as
they will definitely be at the end of there usefull life also.
Why not bore to maximum oversize and gain some power in the process? .
Paul.
quote:
Originally posted by ned
Hi all,
I finally got the chance to strip my (vx 16v) engine down last night (well as far as the block anyway) to find IMO considerable wear on the bores.
The lip at the top of the cylinder is quite substantial, the sort you can catch your nail on (and almost certanly would catch a piston ring if the
piston went skywards).
From my understanding I can either have it honed out/rebored and fit oversize pistons or resleeve the cylinders back to standard (I know someone who
did this @ cost of £300)
Can anyone tell me how much a rebore + set of oversize pistons will cost? (ball park figure?)
I'm also considering racing with this engine at some point in the future, so I presume resleeving will be best for this incase regulations
don't allow oversize engines/rebores.
Ned.
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david walker
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| posted on 28/5/03 at 10:24 PM |
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0.5mm oversize (AE) pistons and rebore - £185+vat.
Your existing pistons/rings will be shot. To liner the block back to std and supply new pistons would be a waste of money but for the record would be
£345+vat
Dave Walker, Race Engine Services - 07957 454659 or 01636 671277
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Jon Ison
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| posted on 29/5/03 at 02:03 PM |
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99.9% of race regs say standard o/bores only, which in my day ment around +60thou, i see dave is on mm, but thats what i would do, go for the max
overbore using std parts........ and at £185 + the dread'd vat it don't look bad for a nice fresh engine ???
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ned
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| posted on 29/5/03 at 02:13 PM |
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thanks for the replys guys, guess i'll have to wait til i can get the crank out and check that for wear too.
I have since spoken to a vx engine building friend who recons the pistons go oval on high wear bores. i'll have to borrow my mates digital
vernier/micrometer and go about measuring all the right bits and assess the best route, though the resleeve idea is rapidly going out the window...
Thanks,
Ned.
beware, I've got yellow skin
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Danozeman
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| posted on 29/5/03 at 07:41 PM |
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IMO a resleeve is a waste of time and money.. rebopre to standard o/size is defo the way to go.. More power and less money.. Unless the crank
needs grinding etc... Then spend loads of money and get it race built..
[Edited on 29/5/03 by Danozeman]
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david walker
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| posted on 1/6/03 at 08:32 PM |
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Sorry Ned but all pistons are oval. Not really sure what you are going to measure but if you want a tip, what matters is the ring grooves. Feel for
play there, there will be some and so the pistons will be shot. All pistons do is act as ring carriers.
Dave Walker, Race Engine Services - 07957 454659 or 01636 671277
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MattWatson
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| posted on 2/6/03 at 03:39 AM |
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Unfortunately, you may need to resleeve if the walls have too much damage, or if they have been bored before (depending on ammount) You also might
want to check what the maximum you can safely bore it out to.
If it does not need resleaving, don't do it.
Matt Watson
--------------------------------
VW 1.6L SOHC Turbo Mid engined car
http://members.shaw.ca/wavindustries/
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ned
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| posted on 2/6/03 at 09:35 AM |
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I'm now on the rebore route, probably +10 thou, (0.25mm?) the AE pistons are cast i believe? i'm thinking along the lines of forged, such
as Omega (yes i know they're more expensive)
I may well drop some hot cams into the engine at a later date and with an MBE ignition will have it reving over 7000, so would like the forged pistons
(won't explode if something lets go), will get them with pockets in to allow for cams at a later date.
will be using arp big end + flywheel bolts, probably slotted or lightened flywheel, vernier pulleys, dry sump if i find a cheap cateringvan one .
I've got the head and all ancillaries off though was struggling with the bolt on the end of the crank (at the front of the engine where the oil
pump is) I broke a 1/2 inch drive 16mm socket and snapped my 3/8 adapter, all on long torque wrench (had a block of wood in number one crank) will be
off to a mates tonight to get this damn bolt out, then i can have the crank out and have a proper look at everything.
I'll update when I've seen the pistons and ring grooves. (and found if the crank needs a regrind - this is getting expensive!!)
Ned 
beware, I've got yellow skin
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david walker
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| posted on 2/6/03 at 08:51 PM |
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Ned,
I am not aware that Omega do a .25mm piston but they may. There is only one size of "oversize" from AE (or Mahle) and that is +0.5mm.
Iwuld suggest that you take a look at Accralite if you go the forged piston route. Cheaper and IMO better.
It's a big cam that needs cutouts in the pistons but you can have pockets put into std pistons. I'm not keen and always use forged pistons
ready pocketted, but QED do it, even on their 220bhp engines. To go that wild you'll be needing solid lifters and all that entails, so
it's a bit more than "dropping cams in"!
7000 revs/min is nothing for an XE (with ARP rod bolts fitted). You'll not break std pistons under 8k and probably not without going well over.
ARP flywheel bolts are a waste of money in a 16 valver. Use new Vauxhall ones and save money. You (or anyone else on here) have never seen a flywheel
come off one of these when (correctly) fitted with such.
To remove crank pulley bolts you need a decent air impact ratchet.
Crank grinds are cheap (in comparison) - £35 + vat here. Get it balanced when you buy that expensive flywheel and, I assume, paddle clutch.
Dave Walker, Race Engine Services - 07957 454659 or 01636 671277
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ned
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| posted on 3/6/03 at 09:07 AM |
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David,
Thanks for your comments, I had a long conversation yesterday with a guy at QED.
The crank does need a regrind (took a main bearing off yesterday, but still didn't shift that damn bolt. am going to mates workshop to use his
3/4" drive and accetylene torch on it - blow torch and 1/2 wrench didn't touch it!)
I've heard acrylite pistons aren't as good as omega (from race paddock talk) I also didn't think you could get Mahle pistons
anymore?
oversize pistons are 86.05, 86.25, 86.5, 87, 87.5, 88 , though if i go upto 88mm, i get a 90cc increase. (2092cc) though qed said this wasn't
worth doing. I was thinking of flat top pistons (with pockets + maintaining 11:1 compression ratio)) and obviulsy rebuilding the bottom end, then I
could either start with standard cams or fit qed's 38h profile which they say on a decent engine gives 210bhp (thats a hydaulic profile)
i can't see the point/don't want to go to solid lifters as the cam lift (on even bigger cams) will i think be in danger then of allowing
flow through and failing mot emissions. I also then loose torque and need to rev the engine higher. I was probably going to run a 7500 soft cut rev
limit.
I've thought of using the arp flywheel bolts as the vauxhall stnadard ones are stretch bolts and will ned replacing, whereas the arp ones
won't (I'm sure the engine will be apart again at some point in the future)
i also intend running vernier pulleys but retain the standard head, springs, valves (possibly wasted stem valves at a later date).
Any other suggestions/comments/opinions greatly received.
Andrew.
[Edited on 3/6/03 by ned]
beware, I've got yellow skin
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david walker
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| posted on 3/6/03 at 07:22 PM |
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Ned,
You have obviously done some research, so OK.
Was it Paul Exon you spoke to at QED? He's a top knob there, his dad's a mate and he has an XE engined Locost!
I bought a set of Mahle pistons for an XE about 3 months ago, no problem. For std/mild performance gains I have had no problems with the AE pistons.
Price about same also. Mahle in the UK have had serious problems this last year or so, as they seem to have used two or three importers, who after a
short while seem to drop them. I have bought their pistons for other applications in the last few weeks though.
I have not herad any negative comments about Accralite, just the opposite. I'm genuinely interested what they are, are they based upon fact or
rumour?
My long standing problem with Omega is that - at least the last time I spoke with them directly - is that they now have agreements with their
stockists not to sell directly to engine shops, which is something they used to do. To become a stockist you have (or had) to buy 20 sets of any type
and size of piston that you required at the time. At the time I was looking for about three sets of Mini race pistons. Their stockists then, maybe
understandably want to take your eyes out!
I understand your logic with the solid/hydraulic lifter argument. I don't agree with it as in my opinion forged pistons and hydraulic profiles
are an expensive contradiction. QED are good but remember they are selling kit. There are some excellent profiles from Kent & Piper that will see
over 200 bhp on hydraulics AND std pistons.
If you are building a kit car / se7en you have no MOT concerns about emmisions.
Finally, whatever Vauxhall say their flywheel bolts are not stretch bolts. Like any other critically tensioned bolts, including ARP, you
shouldn't use them more than 2 or 3 times. What they do have though is a locking compound attached to the threads. After first use I use
Loctite.
Keep us informed on your progress as I'm interested.
Dave Walker, Race Engine Services - 07957 454659 or 01636 671277
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ned
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| posted on 4/6/03 at 09:29 AM |
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David,
It was a guy called Ken I spoke to at QED.
As you may have guessed my experience with these engines is from the national supersports series which utilises the xe engine to a spec regulation.
(www.nationalsupersports.com)
I guess this may be giving me a narrow viewpoint in certain areas.
To answer your question, the comments I've heard re: acralite is purely that they're just not as good as omega, this came from an engine
builder (John Harrison Engines?), though I assume they know this from engine failures or dyno tests or something.
Back to the AE pistons, I want to build a solid bottom end using forged pistons(pocketed), though standard rods + crank (arp bolts)then leave the top
end standardish for the mo (money isn't that plentiful!) but have the bottom end capable of taking increased cams(hence pocketed pistons),
compression ratios (toyed with the idea of skimming a bit off the head) and wasted stem valves.
As I don't intend to rev the engine that high (upto 7500ish) I think I'll be able to get away with a hydraulic profile; otherwise I get
into steel crank and rod territory which has to be another £1600+ for 8-9000+ rpm engines. I'd appreciate your suggestions/comments on this
please!
I'm still considering boring the block out to 88m as it won't cost me anymore than a standard rebore (well, maybe £20) the pistons also
seem to be no more expensive for 88m ones.
I'll have to do some searching for info on pistons, omega, acralite, mahle etc and see if i can draw any conclusions/price comparisons. I assume
new pistons come complete with rings and gudgeon pin>(haven't asked anyone this specifically yet, stupidly)
I'll post any info I discover...
thanks again,
Andrew.
beware, I've got yellow skin
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