Adam M

My fear would always be the rods when wanting to hold 1.5 bar.

Some people have been fine, others havent, but even then we dont know if the engine failure has been because the rods are weak.


Dont think the P18 is going to help much. If it has trouble it has trouble, you can change it if it does.

I dont think you should be so concerned about the boost numbers specifically, but concentrate more on getting a better map with the boost you choose to run. For example water injection. Theoretically the amount of torque you can extract per degree of ignition advance is very impressive, so I would turn my attention towards improving what you have now.

WI also improves consistency, so you wont neec drastic changes between summer and winter.

If still unsatisfied, then you should think about the other options such as increasing boost.

David_Wallis

how easy is it to use air injectors with the std ecu??

Would these give better boost control?

David

R19KET

David,

IMO, it's not realistic, or really worth trying.

Air injectors are really designed to work with external WG's, where you can apply pressure to both sides of the diaphram. This also requires two independent PWM's, to work correctly.

I'd make sure that actuator is up to the job, and can stop the WG being blown open, and then ask Andy F, how he's set his up.

Mark.

David_Wallis

ahh, is that why there is allways two? (that I have seen)

Whats the std td05 actuator good for, or should I replace it?? can you recommend / supply one??

David

Stelios

As my MoTeC has data logging capabilities please note (MY00):
Induction+HKS manifold+GGR exhaust+cat+VF22+ Apexi AVC-r boost controlling tapering from 1.25 4,000rpm to 1.1 bar at top note at 7000 rpm (abt 340 bhp) injector duty 85% (just ok).
So 440 injectors *just* marginal please take care of max boost vs inj. duty cycle (though 1.5 bar witha VF22 is different than 1.5 bar with VF29 etc as mass air flow different).
IMHO i would trust Pat and Bob blinfolded and I NOT his customer.
Hope it helps.
Also loking for uprated injectors/fuel rail advice pls?

john banks

From what I hear (I have not tried a 3 port as I have no need to) the 3 port if you want boost hitting targets in lower gears still gives you a 2 PSI overboost on changing from 4th to 5th. I personally really don't like boost spikes. With a Dawes on my car I get full boost in gears 2-5 with no spikes whatsoever even on datalogs. That might be because I use a small bleed hole and a tight actuator. You can also adjust it for the track very readily. The Dawes does not suffer with boost spikes on track like most other boost control methods. You also lose the second gear half boost. You lose the ECU's ability to shut off the duty cycle in the event of uncontrollable knock, hence the need for a Knocklink IMHO.

Like ECUs, no one method suits all cars and users.

You kind of answered it for me in your post - you get boost spikes up to 0.1 bar over held. I get 1.5 bar every time once the car is warm without any spikes at all. And it cost me £25.

[Edited by john banks - 10/11/2002 1:43:37 PM]

john banks

Bob, is it possible with a 3 port to hit boost target without any spikes in gears 2-5? If so I'll try one. If I am going to have to overboost to 1.6 bar to hit target then I might give it a miss as I'd have to pull my timing down to cope with the spike, and I really don't want any more boost (well I do but I don't )

I am puzzled at the Dawes being a bleed, the only bleed in my system is the tiny one to stop boost being trapped on lift off. Covering it up makes no difference to held boost - with the bigger turbo I keep it really small which does benefit control and the part throttle is great. I know it is a bit of a kludge but I could not wish for better boost control to be honest.

[Edited by john banks - 10/11/2002 6:39:05 PM]

Bob Rawle

Andy ... just so ... the difference being it's a variable bleed and can be part of a closed loop system though which a straight bleed cannot. You could always use a linear motor driven valve to do the same as the ecu does in pwm'ing the valve.

John not going to get picky about terminology ... its a bleed as it allows air to "bleed" ie leak away from a pressure system ... it is a pressure relief valve as it does this at a pre-set pressure point. I've been around pneumatics and hydraulics too long to change what I call things. So we have a pressure relief valve cracking open to then bleed pressure away from the actuator at a fixed rate ...

Why would you need to pull timing ... if you change the load scaling to match what you are trying to achieve then boost for boost (load for load) you can run exactly the same timing, just naturally reducing, load is not all about boost of course. The only time you get into trouble with this is if you are running the turbo into surge or into choke. Then you get same or less flow as boost increases. But thats about not pulling the boost in too hard on light throttle and sizing your turbo to suit the application.



[Edited by Bob Rawle - 10/12/2002 8:55:41 AM]

john banks

I'll try the 3 port and see then...

I think 1.5 bar is quite enough though so I don't want any spikes, I am just leaving some small sympathy for my chocolate internals even if it is just psychological, I just don't want spikes to 1.6 bar. Spike to 1.5 maybe and settle at 1.4 and the engine might last a bit longer? It is considerably slower at 1.4 bar than 1.5 bar though even though I have to retard the timing to run 1.5 bar a fair bit. The EGTs at the bottom of the uppipe are up to 780C at 1.5 bar, 760C at 1.4 bar.

With the 550 injectors I should be able to get it a bit richer which will give me more timing as it is was too lean with a lambda of 0.87V - I say this because I managed to get considerably more timing by richening it to 0.89 and this combination was certainly no slower, but the injectors can't manage this at the top end. 550s overdue now clearly. As Stephen found an alarming difference in AFR between 0.87 and 0.88 with the wideband I'm sure it will be very interesting.

Maybe if I just ran more sensible boost I would not be so paranoid about boost spikes.

ECU dropping boost with det - I don't miss it as I've not seen it drop the duty cycle on logs when the car has been detting. Knock correction doesn't seem so hot on JECS when you run very high airflows. Maybe there are some other undiscovered knock control maps.

The long and the short of it the Dawes works for me well, that is why I use it. Doesn't suit everyone and it is not the best solution in the world. But I have good reasons for using it. Primitive and embarrassing maybe but there you are. I will smile with my perfect boost control

[Edited by john banks - 10/12/2002 10:30:48 AM]

T-uk

john,

I was meaning,could you not solder up the dawes bleed hole altogether,so that the dawes could be used more as a type of restrictor that would allow quicker spool,less peaks and better held boost with the ecu controlling the solenoid bleed,so that it could still cut boost should a problem occur.when I asked you before I think I was meaning a standard (with bleed hole dawes) not one with the hole soldered up.

I admit,this side of things loose me quickly so if I am blethering p15h just say.

[Edited by T-uk - 10/12/2002 6:17:23 PM]