Engine build progress

marcoturbo · Oct 10, 2009

Rotten head ?

TTM · Oct 12, 2009

Well, that's not what I was told last time I saw the doctor but thanks for the kind word

I noticed that the hose between the coolant rail and the waterpump had a suspect strap, and though it didn't seem to let out coolant I replaced it with a new one, and now the unpleasant coolant smell has gone along with coolant consumption.

TTM · Oct 30, 2009

Currently considering (again) fitting a front-mounted intercooler... Any idea why the http://www.jmgarage.com/ website is down? Last time I looked they seem to make one, some information on it would be appreciated... [

] (just thought I would bump this thread instead of posting a new one that may have been taken as advertisement for JMG)

sawood12 · Oct 30, 2009

I'm convinced the way to go is to lay the IC flat and create a bonnet outlet vent and some shrouding to channel air throughthe IC such that it exits from the bonnet vent. Though might not be possible with the airbox in place and if you ensure you get cool air into the engine to begin with will mean you wont need as large an IC as you'll have less cooling to do.

marcoturbo · Oct 31, 2009

Why not water injection ? Of course, if the right sheets are sent by the seller... [

]

TTM · Nov 20, 2009

Here is an update on Sly's car. Bad news I'm afraid [&:] Sly noticed a loss of compression on cylinder #4, oily 4th spark plug and exhaust header black in the fourth runner. Apparently some oil was getting in the combustion chamber. He took the head off expecting to see a much scored cylinder wall, but the bore and piston are spotless, as do all three others. Can a broken ring be responsible for this? We thought that a broken ring would necessarily badly score the cylinder wall? My engine is running fine, now done 5k miles. Still struggling with knock that appears when I floor the throttle but disappears as soon as peak boost is reached. This issue puzzles me as from one day to another it will disappear as unexpectedly as it appeared the previous day [8|]

944Turbo · Nov 20, 2009

Knock - is the wiring ok to the sensor? Do you have an alternate one to try? Sorry to hear about Sly's car - don't know the answer though.

Mike_Pollock · Nov 21, 2009

Valve / valve guide on No 4? Broken ring would usually damage bore. Mike

TTM · Nov 21, 2009

ORIGINAL: 944Turbo Knock - is the wiring ok to the sensor? Do you have an alternate one to try?

Yes the wiring is fine. Adjusting ignition retard with the FQS has a direct effect on knock and there are hardly any left with the FQS set on -2Â°, but by then the engine feels less responsive. I am not sure where to start to get rid of this. As knock disappears when peak boost is reached I am tempted to think that the air that gets into the engine is fresh enough and fitting a "more efficient" intercooler might prove useless.

ORIGINAL: A9XXC Valve / valve guide on No 4?

Yes this makes sense ; Sly hasn't yet taken the valves off the head to check.

sulzeruk · Nov 21, 2009

I would say it sounds like a broken ring, possibly the scraper has shredded itself. It would be strange just for 1 guide to wear. Possibly a bent valve, that would result in poor combustion giving you a nice black plug. Alasdair

TTM · Dec 2, 2009

Quick update. Sly took the valves off the head. Exhaust valve guides show a surprisingly high level of play, usually observed on heads that have three times the mileage. Exhaust valves used are heavier than the original ones and are not filled with sodium, which probably caused the guides to wear more quickly than expected. As exhaust guides are equally worn, this doesn't really explain why oil made its way into cylinder #4. The "lean spike" that takes place on my car when I floor the throttle and the related knock blink observed may be caused by still using the original fuel pump. 83lbs injectors (more than twice the output of the originals) may cause for a short moment a drop of fuel pressure in the fuel rail when opening the throttle wide - does that make sense?

DivineE · Dec 4, 2009

ORIGINAL: TTM Quick update. Sly took the valves off the head. Exhaust valve guides show a surprisingly high level of play, usually observed on heads that have three times the mileage. Exhaust valves used are heavier than the original ones and are not filled with sodium, which probably caused the guides to wear more quickly than expected. As exhaust guides are equally worn, this doesn't really explain why oil made its way into cylinder #4. The "lean spike" that takes place on my car when I floor the throttle and the related knock blink observed may be caused by still using the original fuel pump. 83lbs injectors (more than twice the output of the originals) may cause for a short moment a drop of fuel pressure in the fuel rail when opening the throttle wide - does that make sense?

Not really. I'm not speaking from any experience on the subject but I'd have thought logically that if you've been using light throttle a pump with insufficient flow would have had a chance to build up pressure (like putting your finger over a garden hose) so you'd have best pressure as you first open the throttle, weakening of as the boost and revs built to maximum demand. One thought I had reading this was that the mapping is always designed to lean the mixture just before the turbo spools to encourage earlier spool up, then get richer to protect the car as the boost builds. If the shape of the map was now out of sync with the spooling of the turbo due to the extra capacity.. the map could be going lean temporarily as the boost is building causing knock. Did you ever sort the white smoke from the exhaust problem which went away after some full throttle?

TTM · Dec 4, 2009

The thing is that the fuel pump delivers a constant fuel pressure, and it can apparently keep up with injectors flow as I can get the right AFR when max boost has settled, so yes I don't really see why there would be a temporary pressure loss in the fuel rail. I tried with a cone filter in place of the Airbox but the "lean spike" got worse [

] I could add fuel in the low rev/high load area of the map but if I do so the AFR will be way too rich on part throttle. I could try to control fueling with boost but as others with a similar set up don't need to I would like to solve the problem with the current set up. Still no idea on what caused the engine to burn coolant, but the headgasket is still fine.

Diver944 · Dec 4, 2009

It may be useful to measure the actual fuel pressure at the end of the rail when this lean spike occurs. If the pressure remains constant during the spike then it at least rules out the pump and FPR. The cone filter is obviously allowing even more air through which makes the lean spike even worse. Is there anyone else nearby that has the Vitesse MAF that you can swap with so as to rule out a fault in the MAF itself?

DivineE · Dec 4, 2009

Wow just went back and read this post from start to finish! Can't beleive I missed it till now!! What a project. Really sorry your having troubles after all that impressive work yourself

I'm sure there'll be an easy fix though. Really interesting to see just how similar your descriptions of power delivery, fuel economy and increased heat are to my old 3.2, its amazing how two such different builds can give such similar results. I really like Pauls idea for ruling out a fueling issue.. really really off the wall guess but could it be a faulty injector? Either not reacting well to a lesser flow (ok cruising but not when under load) or maybe if it was slightly miss shapen and had an odd spray pattern which became more regular as flow/pressure is increased? Edited to add: On the coolent issue. Obvious I know but have you re-torqued the head bolts?

DivineE · Dec 4, 2009

Sorry I keep thinking of things but on the oil in the inlet (2.5 car) that would be in line with others findings about oil being drawn out of the sump through the breather lines. I've read a few cases of that where people running big turbo's have had their oil catch cans filling up fast.

TTM · Jan 22, 2010

After 6 weeks of no use I took the car out for a short drive on sunday and was pleased to notice the cold has had no ill effects - well ok, the driver's side door lock played up a bit at first but worked fine again when I got back home. After 6 weeks of daily driving the Clio I was shocked at how stiff the clutch felt, too [

] Some progress on the intake is due for the weekend. I got a MAF pipe from SFR in the US (not cheap for what you get, and it looks like it will still need to be modified somehow) and after extensive searching fellow Marc eventually sourced a well-sized cone filter made with proper paper filter. This means we we will probably kiss the airbox malarkey bye bye [

] Methinks there won't be many cars that will be able to follow the White Rabbit on the Autobahn once the nice days will be back.

JarmoL · Jan 23, 2010

ORIGINAL: TTM The "lean spike" that takes place on my car when I floor the throttle and the related knock blink observed may be caused by still using the original fuel pump. 83lbs injectors (more than twice the output of the originals) may cause for a short moment a drop of fuel pressure in the fuel rail when opening the throttle wide - does that make sense?

Hi there, I guess I have somewhat similar problem with my 2.8 stroker engine. Wideband shows lean condition briefly when accelerating rapidly and car stumbles once before it gets going. It seems to happen around the point when the manifold pressure changes from vacuum to boost. It kind of feels like it hangs a second too long on closed loop until it goes to WOT maps. After that single stumble AFR's are ok all the way to the redline. I have Vitesse software and Maf along with associated mods. Fuel pump is stock though. I have chased the cause for this for some time now. I have changed many obvious parts as TPS, plugs, distributor cap, O2 sensor etc. Fuel injectors have also been professionally cleaned but the problem still exists. It doesn't stumble with cold engine though but that's because the car runs quite rich while warming up? I will change new(bigger) injectors and install resistors to get proper resistance. Also have to try with another DME box.. could be there's some heat related damage because running those injectors without resistors?? (I doubt it though) Might also install new fuel pump and the check valve next to it. I guess it would be logical to suspect the Maf itself too.. [8|] I asked John to update the sofware to latest version but it costs 600$ so I am not very keen to try that at the moment. Problems like that get very frustrating very quickly.. and the troubleshooting gets expensive while many parts have to be changed when the root of the problem can't be found. [

] So.. Thom if you get it fixed for good.. please let us all know! Jarmo

barks944 · Jan 24, 2010

If the car is running lean then under those conditions its either the injector pulse width too low or the fuel delivery system is failing to keep the pressure differential between manifold and fuel rail correct. Finding out which is probably key to finding your problem. I guess the fuel pump runs at a constant flow rate, so as your not really testing the flow rate of the pump at low rpm it may be the fuel pressure regulation. Damper and or regulator not doing its job. From what I understand the vitesse maf runs constantly in closed loop mode. Its possible the maf doesn't see sudden changes in air flow immediately. How long does it stay lean. Does it do it at partial and WOT?