A wideband Lambda setup costs less than a session on the rollers and, with patience you can map the fuel really easily - and have a gauge to tell you precisely how things are going long before anything lets go.
Having talked to lots of you guys one thing most seem to agree with is that one of the probably causes of our engine going bang last weekend was
probably running very lean.
What could have caused it to run lean, most of the summer we've had an overfuelling problem, first due to the facet/filter king como, then due to
the drainpipe size main jets Bogg Brothers fitted. We then swopped to 40mm main jets and the car seemed to be running fantastically until.......
Have we dropped down to too small a jet size or is there some other reason we could be running lean, plugs looked maybe a tad lean but not overly
so.
Just worried if I bolt the same carb setup onto the new engine I'm going to have the same problem
You could fit an lambda probe and gauge. Then at least you could catch it before anything bad happens.
Did you rolling road it after the change of mains?
If not how do you know the set up was OK?
Were the correct type of spark plug used, i.e the temperature of the plug, if this got too hot, could lead to detonation, or the possibility of the tip of the plug coming off, which could cause engine failure
quote:
Originally posted by snapper
Did you rolling road it after the change of mains?
If not how do you know the set up was OK?
quote:
Originally posted by locost750mc
Were the correct type of spark plug used, i.e the temperature of the plug, if this got too hot, could lead to detonation, or the possibility of the tip of the plug coming off, which could cause engine failure
It would depend on the spec of the engine, if it was standard ish, i.e the same compression etc, i cant see the plugs being the problem, if the engine had different pistons or lairy cam, or higher rpms for a longer period than normal, could be a problem.
I'm afraid your situation is a classic example of using guesswork and racing - they just don't mix. You might be able to get away with the
odd lean spot on the road but when you are 'going for it', the engine will let you know when something goes wrong ..... need I say more?
A wideband Lambda setup costs less than a session on the rollers and, with patience you can map the fuel really easily - and have a gauge to tell you
precisely how things are going long before anything lets go.
quote:
Originally posted by RazMan
I'm afraid your situation is a classic example of using guesswork and racing - they just don't mix. You might be able to get away with the odd lean spot on the road but when you are 'going for it', the engine will let you know when something goes wrong ..... need I say more?
A wideband Lambda setup costs less than a session on the rollers and, with patience you can map the fuel really easily - and have a gauge to tell you precisely how things are going long before anything lets go.
I got mine from this guy on eBay - from Latvia would you believe.
http://cgi.ebay.co.uk/INNOVATE-DB-BLUE-LED-WIDEBAND-GAUGE-KIT-LC-1-02-SENSOR-/290384467531?cmd=ViewItem&pt=UK_CarsParts_Vehicles_CarParts_SM&h
ash=item439c43564b#ht_4070wt_1137
A couple of hours to install properly or you can rig up a temporary setup and sell it on when you are done setting up your jets. The reassurance that
your mixture is spot on is very comforting to the wallet 
What razman said. I bought a similar kit but with the XD-16 gauge as I found it easier to read (with the outer LEDs in additional to the numeric
display).
You can also log the output using a PC with their free software.
If your after a locost Lambda for your car, your could try on of the DIY companies.
http://www.14point7.com/NAW_7S.php
This may be a little harsh but you've basically been asking for this..
you've fitted carburettors to your engine that were designed to fuel a bike with completely different characteristics. Bogg fit such big jets to
"get the car running" because bike carbs tend to lean out as the revs climb, so they prevent any problems with this. The trade off is that
the engine bogs down but they'd rather that happened than you blow a hole in a piston by having jets too small. It doesn't matter how good
Bogg are, they can't provide a tailored fueling solution unless you give them the car.
So you replaced these jets with narrower ones, again a generic solution to lean the mixture out over the entire rev range. You then started racing the
engine without checking the fueling on a RR or even with just an O2 sensor.
Add this to the fact that you're running an ignition map that isn't set up for your engine and could be causing spark mistimings.
On top of all THAT members on here have told you repeatedly to get the car looked at by a professional on a RR to set up both fuel and spark and it
starts to look like this wasn't as unexpected as perhaps it appears..
As a previous poster has said, what you get away with on the road doesnt apply on the track. You spend all your time either flat out or in the pits.
If your ignition was a little on the high side, your mixture a little lean, your engine temps a little high and a high ambient air temp....one
destroyed engine.
We do bike carbs and we dont guess it.
With todays engines plug cuts and tuning by ear have long gone, you have to have the car set up. The flame front in the head is bang on accurate,
unlike the old cars, so ignition and fueling has to be accurate as well.
Sorry to hear about your problems, rolling road it is my advice.
Alan
[Edited on 15/7/10 by atspeed racing]
quote:
Originally posted by cd.thomson
This may be a little harsh but you've basically been asking for this..
you've fitted carburettors to your engine that were designed to fuel a bike with completely different characteristics. Bogg fit such big jets to "get the car running" because bike carbs tend to lean out as the revs climb, so they prevent any problems with this. The trade off is that the engine bogs down but they'd rather that happened than you blow a hole in a piston by having jets too small. It doesn't matter how good Bogg are, they can't provide a tailored fueling solution unless you give them the car.
So you replaced these jets with narrower ones, again a generic solution to lean the mixture out over the entire rev range. You then started racing the engine without checking the fueling on a RR or even with just an O2 sensor.
Add this to the fact that you're running an ignition map that isn't set up for your engine and could be causing spark mistimings.
On top of all THAT members on here have told you repeatedly to get the car looked at by a professional on a RR to set up both fuel and spark and it starts to look like this wasn't as unexpected as perhaps it appears..
I appreciate that you have not had a good experience with another rolling road, but you cannot get the engines setting correct without using one.
Sometimes near enough just isnt good enough, as you have now found out.
Not all rolling roads are bad and it doesnt mean that the previous company did a poor job, perhaps there was something not right with the car?
Maybe you should have taken it back and asked for the advise. Most small companies would rather spend another few minutes looking at something than
having a customer that isnt happy.
As you say, you will learn from this.
Good luck.
No, I'm not suggesting that all rolling road companies are bad or even that the one I used was bad, just pointing out that 12 months ago I had no
choice but to use a pro garage for everything, I had no knowledge at all. I just needed to start doing stuff for myself (a) because I wanted to learn
and (b) it was too expensive to do it any other way. I'm realise that the car needs to be rolling roaded to get it 100%, just want to do as much
as possible myself to learn more than anything. I didn't realise (obviously or I wouldn't have run it) that without it it basically
wasn't OK to drive at all, I assumed it would driveable if maybe not running particularly well but driveable.
As I said, I'm new to this and I accept I'll make mistakes but (as per the original question) when I make a mistake I'm determined to
learn from it by understanding what that mistake actually causes to happen inside the engine. That's why I come here, you guys actually take the
time to explain.
[Edited on 15/7/10 by norfolkluego]
I have a similar setup to you - Bike carbs and Zetec.
I built a JAW wideband lambda kit and used this to set my carbs up. A rolling road would have been better, but at the time I didn't know of one
other than Boggs that did bike carbs (and they are too far away).
Anyway, my car has been fine set up with the wideband. It goes well, hasn't blown up yet [done several track days] and does good MPG, so I must
have got it about right!
I would go to Atspeed or somewhere like that if you can, but failing that for about £120ish a wideband setup will allow you to safely tune the
carbs.
Stu
just bought myself a wideband too one of the innovate LC-1 kits off ebay
to self tune its a must have so my advice would be
zetec engines are cheap as chips buy the wideband and experiment