pigiron
|
| posted on 29/11/11 at 03:41 PM |
|
|
Kent Xflow low-comp pistons sugestions
Subject: Inexpensive low-comp piston solution, supercharged 1600 xflow.
I am in the process of getting together the required bits and pieces for a supercharged Kent 1600 711M crossflow project and in the true spirit of
Locost the object is to keep spending to a minimum.
Already I hear voices saying "why bother .... fit a Zetec" but for this project I must keep things period looking so an engine change is
out of the question, so please humour me.
I’ve managed to find all I need except for pistons, to purchase new forged ones would be all too easy but defeats the object of this challenge.
In any case from what I read by Corky Bell forged are not really compulsary on a well tuned, lowish boost road application, in fact he suggests that
cast can even have certain advantages, therefore I was hoping that perhaps someone on this forum may be able to point me in the right direction, I
would like to run about 8 to 1 compression ratio.
What I am hoping to find is a piston from perhaps another engine which shares the same size pin size and similar compression height etc, I have a
lathe and enjoy messing about so no probs in that direction.
The bore is currently +090” which limits thing a bit, I live in rural France and 711M blocks are somewhat scarce here. I was thinking of boring to
83.5mm but the only piston I can find is the expensive Acralite sold by Burton.
Any ideas gentlemen?
|
|
|
|
|
britishtrident
|
| posted on 29/11/11 at 04:09 PM |
|
|
The xflo was never a popular choice for supercharging
Easy way and safest way is a de-compression plate -- ie thicker gasket.
http://www.fordaustraliaforums.com/forum/showthread.php?2727-250-X-Flow-Turbo-Parts&s=a1204fd3ef6b1653d31336b4a6721738
http://www.ferriday.co.uk/cnc/decompression_plates.shtml
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
designer
|
| posted on 29/11/11 at 04:22 PM |
|
|
Interesting.
I have the same engine, 600 711M, will keep an eye on this topic.
|
|
|
MikeR
|
| posted on 29/11/11 at 06:14 PM |
|
|
I seem to recall reading that the aus / NZ used to use something from a datsun. It was the same basic size and only required minimal machining. It had
some advantages with the crown height and being forged as standard. But I could be talking complete poppy cock.
Wasn't there also some option (with machining) to fit a fiesta diesel crank which did something nice (maybe raise compression which i appreciate
isn't what you want).
Instead of pistons - couldn't you fit shorter rods from a 1300 engine?
|
|
|
luke
|
| posted on 29/11/11 at 06:36 PM |
|
|
When i had a Xflow i did alot of reading on turbosport forums http://www.turbosport.co.uk/
Those guys know everything and anything about the xflow. I remember alot was mentioned about the 1300 rods been used in 1600 engines to lower
compression.
Hope it helps
Luke
|
|
|
pigiron
|
| posted on 29/11/11 at 07:28 PM |
|
|
1300 rods, why didnt I think of that ... must be age, will go and check it out.
I fell upon this just a few minutes ago, very informative.... http://www.rsmotorsport.com.au/forums/viewtopic.php?t=53
Keep the info coming, love reading this stuff ... many thanks.
|
|
|
Confused but excited.
|
| posted on 29/11/11 at 07:56 PM |
|
|
There is a great deal of information about swapping pistons to achieve a desired compression ratio in David Vizard's book 'Tuning Escorts
& Capris', pages 42/43. Got mine off the bay for a couple of quid.
HTH.
Edited to say: Just followed the link to rsmotorsport and noted that in the first photo, showing the 3 different piston types, it states that the one
with the large bowl in it, is an 1100. Yet the next to last photo in the post, shows this as being from a 1600.
Moral: ALWAYS check your info from more than one source.
[Edited on 29/11/11 by Confused but excited.]
Tell them about the bent treacle edges!
|
|
|
rusty nuts
|
| posted on 29/11/11 at 08:16 PM |
|
|
Not sure if they were low compression pistons but some Transits used the cross flow lump which may be an option? Thinking about it some cross flow
engines had a sticker on the rocker cover with either LC or HC so low compression pistons were available at on time
[Edited on 29/11/11 by rusty nuts]
|
|
|
02GF74
|
| posted on 29/11/11 at 08:22 PM |
|
|
quote:
Originally posted by MikeR
I seem to recall reading that the aus / NZ used to use something from a datsun. It was the same basic size and only required minimal machining. It had
some advantages with the crown height and being forged as standard. But I could be talking complete poppy cock.
Wasn't there also some option (with machining) to fit a fiesta diesel crank which did something nice (maybe raise compression which i appreciate
isn't what you want).
Instead of pistons - couldn't you fit shorter rods from a 1300 engine?
if memory severs me well, the datsun conversion was to be able to use a steel crank instead of cast - machining was involved.
re: diesel crank, this has slighlty longer throw so a gain in cc is achieved. it needs the nose machined plus custom flywheel as it has 8 instead of
the usually 6 bolts.
using 1300 rods is not advisable on the longer throw 1600 crank - the rod to throw ratio needs to be 1.6 or longer (there is reason for that which
esscapes me but has to dow with keeping the rod angle low) - I looked into this as I have said diesel crank sitting in the kitchen - custom rods
I'm afraid.
How about taking some metal off the piston if you have access to a lather or as ^^^^ said, decompression place.
Pretty sure there has been supercharged crossflow or two and again from memory, there was not need to reduce CR.
Another option is to fit the earlier chambered head - you would need to do the sums but I reckon the CR would be too low (should you decide to go that
route, I have such head very ported with big valves sitting in the back room).
|
|
|
MikeR
|
| posted on 29/11/11 at 10:39 PM |
|
|
Ahhh, starting to come back to me now - that sounds like what I was remembering.
As for the rods - the rod angle affects the thrust on the piston, the smaller the angle, the less sideways thrust the piston gets. In this case, less
is good as it reduces friction and ovalisation of the bore / piston wear. I've now got a vague memory that the crossflow has quite a lot of
sideways thrust in its normal standard design so increasing it isn't a great idea.
As usual, i could be talking poppy cock.
Decompression plate seems to be the easiest option at the moment.
|
|
|
madflow
|
| posted on 6/1/12 at 03:16 AM |
|
|
low comp piston alternative
xflows are fine for supercharging ,problem was back in their day the superchargers available needed lots of tlc and expert/experienced installation,
block ,rods and good quality pistons are more than up to it , just look at zakspeed capris 450 bhp on high boost running cast iron 1300 kent blocks
(admittedly steel cranks and rods ect ). Cast xflow pistons in general are not a good idea, bad design around the top and dont take kindly to much
machining , there are afew good brands but the price difference between them and some forged ones isnt that big, modifing adapting other pistons is
possible but can work out more expensive. Its the machine work envolved--good thing you have a lathe--so you need to get them for free or very cheap,
which is where quality goes the window and you dont want to be investing hours of freetime and work on something thats going to grenade after a few
hours run time.Most of the alternative pistons are just as much as good bespoke ones, i have built using alfa 1500, datsun 510, pistons--all modified
, but only because there was nothing else to use .I know of kawasaki and vw pistons being used but same reason again --not because they are cheaper
--just available and good design/quality. The datsun crank option was only cost effective if you lived in s.africa , australia ,new zealand
---basiclly any where too far away from the british market and postal service, heaps of work envolved /machine time , but very good result and
boasting rights.My current engine has the ford 1.8 diesel crank and rods also lots of my time in it ,using toyota supra turbo pistons,not supercharged
unfortunately but im collecting for that in the next engine .There is another alternative to the decomp plate and bigger bowl piston, dont go down
the shorter rod path --thats misleading,as it creates more problems , and it doesn t even come close to solving any. Use an older 1600 gt head , this
has a small chamber --bit of fettling it can be made bigger with out going overboard on it--combined with a 1600 lc piston design and you got the comp
down , dont believe all the negative about it being a bad head for flow (doesn t matter any way with supercharged) read a book by JOHN DALTON and see
what he managed .Also use a merc super charger and forget those old units they will all need expesive overhalls/parts and blow up. cheers
|
|
|
pigiron
|
| posted on 31/1/12 at 04:49 PM |
|
|
New forged pistons it will have to be .... but I am having a job sourcing them.
I spoke to a very knowlegable and friendly chap at Omega/ Acralite to no avail, there seems to be nothing low comp available or mod-able.
From searching the interweb I have found several references to the PPC magazine supercharged xflow project a few years ago, I've mailed them
asking which pistons they used and await a reply.
In the mean time does anyone know what they fitted or have the articles?
|
|
|
BaileyPerformance
|
| posted on 31/1/12 at 05:19 PM |
|
|
What sort of power are you hoping for?
As standard the 1600cc engine was not high compression anyway, 9/1CR i recall so you could run 8-12PSI with an intercooler with no problem. Changing
the pistons would be an expensive option, the decomp plate is best described as crappy so i suggest you steer clear of that idea.
We are in the process of assisting a customer who is turbocharging a 1300cc xflow at the moment. Stock engine, vectra diesel turbo, small intercooler,
single point injection (Jenvey) with Megasquirt engine management.
I will post the results when it's done, looking for around 100BHP with good MPG.
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
|
Paul Turner
|
| posted on 31/1/12 at 05:31 PM |
|
|
Hi
I looked at Supercharging a bored 1.4 x-flow back in about 1992, the 1.4 equivalance formula would have given me the equivalent of a 1960 N/A engine
which I needed for the class I competed in with promise of cheap engines and a "free" Sprintex supercharger.
It did not work out for many reasons. I planned to use 83.5mm Omega pistons modified as necessary (the easy bit) but at the hoped for 180 bhp the
crank and rods were well beyond their design limits, the most powerful 1.3 sport was 72 bhp, I was hoping to get 2 1/2 that amount of power. Steel
rods and cranks were not cheap and second hand ones never came up. The pulleys for the supercharger were proving difficult to route even though I had
seen an identical chassis with an identical supercharger on a 1.6 CVH. He had used a modified XR3i injection system for fuel/spark and that made
things a bit easier plus he only had 150 bhp max. On a x-flow an injection system need making up from scratch.
I gave up and built an 1860 x-flow with 2nd hand steel internals that went onto provide me with many class wins, OK it only gave 175 bhp but it never
let me down and it was relatively cheap.
The standard 1.6 internals will be well beyond their capabilities especially the rods, unless you go steel you may well wreck your nice new pistons.
The standard internals were made with a CR of about 9 to 1 in mind, not 8 to 1 boosted.
For your information Vauxhall XE 2 litre (red top 16V) pistons could be used in a x-flow but you really needed an AX block or a very well linered 711M
to bore out to the 86mm needed and even then its was risky. The pistons were very good quality (forged) and had lower crowns but considering the
engine has been out of production now for 17 or so years are there any left hanging about.
A company called Arias Pistons existed some years ago who would make single sets to a design, no idea if they are still around, they made pistons for
many x-flows that raced in the 90's in x-flow Caterhams. Their website still exists http://www.ariaspistons.com/ but they are in the states
unfortunately.
|
|
|
rusty nuts
|
| posted on 31/1/12 at 06:22 PM |
|
|
ISTR Cambridge Motor Sport can supply pistons made to order, might be worth a phone call?
|
|
|
.jpg)
