Dyno Graphs

[Fen]

Thanks for the kind offer, Paul, but if only it were that simple. LS1 - I'm sure I don't know what you mean... []

Looking at last year's plots to check (available here if anyone wasn't aware http://www.cannell3.co.uk/944 UK League.htm) I think it's fair to say a dip in the AFR curve is not unusual on cars with the standard Motronic management. That isn't to say they all do it and on some it's much more pronounced. It is far from what you are looking for, though. My AFR is not perfect, but it's pretty good so I have attached my plot from Friday for comparison. I think you need to go custom map, probably with some hardware that has better resolution than Montronic of the 944 generation to get a straight line. In other words standalone or maybe a piggyback fuel controller.

As Tony suggested above if you are running less boost than the fuel map expects that will manifest itself in the AFR plot as richness, which is a double-whammy of less boost and less efficient combustion of what mixture you do force into the cylinders.

 

[carlmthompson]

I've compared both the graphs of Hilux' and my cars - correct me if I'm wrong Paul, but your car is pretty standard, but rebuilt Turbo?

Basically, the curves are identical until 3700rpm, then:-

@ 4500 Mine = 160/190 vs Paul's 185/220
@ 5000 Mine = 200/215 vs Paul's 235/245

The torque figures return to the same point by the limiter, with my HP being slightly more at that point (by maybe 10) but Paul's peak is at 6000 rpm, whereas mine is at 6700.

I'm assuming this is a classic example of a weak wastegate - again Paul is pulling consistantly higher PSI from 3500rpm onwards, maxing at 13vs11, and tailing back to around the same point by the limiter (although Paul's is consistantly higher all the way through.)

Anybody think differently? Otherwise I need to make the decision between DPW or rebuilt standard waistgate - or even shims. Any suggestions? I'm not keen on visible mods under the bonnet (at least without having to look hard!)

Cheers for comments all!

 

[wizard]

Carl,
How old is your dump valve? If it is old, then this could be an additional cause for loosing power through the range too.

 

[carlmthompson]

Engine has 82000 miles, and apart from a very comprehensive service history, hasn't had any of the main ancilleries replaced.

 

[wizard]

Carl, for a standard car - I'd be well chuffed with those readings, 82K and still making 9bhp more than factory stated!

Mine before was making 220bhp, pulled nicely until about 4K then the power dropped off, this indicated the wastegate not holding any boost. From your PSI chart it could either by DV or Wastegate if I am reading the chart correctly - you are not making full boost.

 

[carlmthompson]

I know I'm not making full boost - and am well chuffed with it making near stanard HP, as I figured it would be down. I just find it strange that the powers there, but not the Torque. I think it may be a combination of both, but am far from being expert!

 

[Fen]

The DV is a good shout. I had sort of forgotten about them, but if you get a £30 SAAB 9000 Turbo one it looks the same and goes straight on, but has a metal diaphragm instead of the original's rubber one. Yours is almost certain to be torn if it's original.

In terms of the wastegate you can't see it unless you get the car on a ramp and look specifically for it, so fill your boots regardless of what it looks like.

 

[carlmthompson]

Cheers for that - I've heard of the SAAB thing before, now you mention it - there's a SAAB dealership nearby, so I'll give it a shot - what do I ask for?

Also, is it easy to fit? I don't mind fitting as long as I don't have to remove half the engine to get to it.

I appreciate the advice on restoring power when your engine is in bits[]

 

[Fen]

I haven't personally fitted one, but it connects to the intercooler pipe and the J-pipe so it's about as accessible as possible in the front of the engine bay.

I guess you ask for a divertor valve. Search on here I think Slim Boy Fat might have posted the part number when he got one.

 

[edh]

To get to peak HP you're going to 6700 - The factory spec is at 6000 I think?
That would explain why you're making the power but are down on peak torque as power is just a function of torque * revs

You have a much flatter torque curve than most other cars - so the question may be; why are you able to maintain the torque but not hit a higher peak?

Boost peaks at 11psi, dropping only slightly by 6700 to 9psi. But other cars running 11psi are making more torque.

Looking at the AFR chart, it dips away sharply at 4500 - about where you are hitting peak torque. Maybe that's the problem?

 

[carlmthompson]

Okay, have done a bit of a Search on t'internet.

You can get a SAAB replacement ones from ECP for £22.88+VAT (actually from a 1992 9000, but am assuming it's the same Bosch item)

There's also an interesting piece on Pistonheads:-

http://www.pistonheads.com/gassing/topic.asp?f=48&t=201239

You only need to read the first post.

From this, Forge and Bailey DV's look like a worthwhile upgrade, while remaining relatively inexpensive (~£100).

Any comments from anybody who's used either before Itake the plunge?

 

[carlmthompson]

ORIGINAL: edh

Looking at the AFR chart, it dips away sharply at 4500 - about where you are hitting peak torque. Maybe that's the problem?

I'd noticed this too, my question is if this is the problem, what is it? It looks to me to be overfuelling - probably because the ECU is expecting more boost (and so more air) than is actually arriving? So does this point at a leak, or again back to WG / DV???

Ohh, and aparently by my logic:-

lack of boost / questions = amount of worms in a can.

 

[Hilux]

If peak power is higher than book ie: 6700 as against 6000 then it suggests to me that its the waste gate or DV as its compensating for lost boost by higher engine and conversely higher turbo speed. At 5252 rpm the torque will tail off (it does in all engines so could be why its low in relation to the power at those revs.

I`m still learning but I bet its boost loss however the low torque issue is a strange one []

Edited to add: Just a thought, could it be a leak on the intercooler side of things?

correct me if I'm wrong Paul, but your car is pretty standard, but rebuilt Turbo?

Yup, standard with 2nd hand turbo 26/8 ??? (the larger one anyway) a few years ago.

Its an interesting quandry as my cars not designated a 951, is a 97 body registered in 1988 with a 220 handbook but the engines definitely a 250bhp engine and its spec`d as a silver rose (sunroof delete) without the upholstery. I keep thinking its a 220 but I`m sure its not.

 

[sawood12]

ORIGINAL: carlmthompson

Okay, have done a bit of a Search on t'internet.

You can get a SAAB replacement ones from ECP for £22.88+VAT (actually from a 1992 9000, but am assuming it's the same Bosch item)

There's also an interesting piece on Pistonheads:-

http://www.pistonheads.com/gassing/topic.asp?f=48&t=201239

You only need to read the first post.

From this, Forge and Bailey DV's look like a worthwhile upgrade, while remaining relatively inexpensive (~£100).

Any comments from anybody who's used either before Itake the plunge?

I've heard bad things about the Bailey recurc valves so I got one from Paragon Products with is a piston type one rather than a diaphram one and i've had no problems with it. They are dead easy to fit.

Lindsey also do a club wastegate which is effectively a reworked single port wastegate but its the same price as a DPW. The beauty of a DPW in my view is that it works from differential pressure either side of the diaphram rather than working against spring pressure. The problem with a spring is that it will never be a truly on/off device as any force acting on the spring will cause a deflection no matter how small (springs are always rated as a deflection caused by a specific force so a smaller force will result in a smaller deflection), so the spring is bound to crack the valve open before you've hit your desired peak boost pressure and fitting a stronger spring will just increase the chances of overboost.

 

[wizard]

Carl, fitting a new DV it is probably one of the easiest jobs to do in the engine bay [] all you need is a screwdriver.
I use the Baily DV on mine for 2 years and not had any issues (yet).
The wastegate is from Lindsey and looks almost stock, however if you have the dual port you will need a boost controller too and then you are on the slippery slope of modifying []

 

[sawood12]

Slippery slidy slope indeed! A manual boost gauge is pretty cheap and appear to work OK but i'm not sure what an Electronic boost gauge does for you unless you want to change your boost setting. I'm not bothered about that as I want to set and forget my boost setting. I've just noticed John's thread on EBC's which i'll be watching with great interest.

But if you see my note higher up this thread about the benefits of a wastegate I think it's a pretty good and effective mod in it's also a very effective mod.

 

[Fen]

Electronic boost controllers make a huge difference over manual (gauges would be electronic vs. mechanical so I assume you mean controller?) The reason is that a manual just sets a boost point and is dumb thereafter whereas an electronic controller monitors the pressure and adjusts a solenoid to dynamically hold a pressure. More advanced versions even let you have a boost map that varies with engine rpm and even the gear the car is in.

 

[sawood12]

Cheers Fen, I did mean controller! I now see the benefits of an electronic controller in that it is a closed loop control system wheras the MBC is just a valve that you set to open at a given pressure. I had imagined that if you simply set your MBC to the max boost level you want it is completely safe in protecting you from boost spikes but I seen now that this is not necessarily the case.

 

[carlmthompson]

Thanks for all the input - I think I'm swaying towards spending £30 on a replacement SAAB item. If it doesn't do the trick, then it's not a fortune to lose, and while i'm tempted to go spend the bet part of a grand on a DPW / MBC etc, I recon my builders might want paying first, or they may take the car as colateral!!

 

[wizard]

Carl, when you have replaced the DV another very easy, effective and cheap modification to do is install a boost enhancer. I used this for a while to cater for my weak wastegate and until I could afford the cost of replacement, it made a very noticable difference and the engine bay still remains looking stock.
I think fitting a boost enhancer is a must for any turbo car.

Jason