Martin’s PRV bone yard…

Andrea,
I had to do away with running my engine on MAP. & now run the setup on TPS. & wideband...the reason I found was the MAP could not keep up with the sudden changes in acceleration, in light or full throttle aplications, & hence the hesitations you may be having.
Eddie.

thanks for the suggest! So what exactly, you changed from speed density to alpha-n mode in the menu ?

Andrea,
Yes...Just by using the TPS. from 0 to 100% & calabrating the AFR. in small incraments, I was able to eliminate all the flat spots & hesitation throughout the rev. range...it may be because I,m on 6 TB,s & they had to be in perfect syncromesh...but I found it VERY delicate to the smallest off changes in ignition & AFR...but now she starts first time & runs like a dream.
Eddie.

Andrea,
Yes...Just by using the TPS. from 0 to 100% & calabrating the AFR. in small incraments, I was able to eliminate all the flat spots & hesitation throughout the rev. range...it may be because I,m on 6 TB,s & they had to be in perfect syncromesh...but I found it VERY delicate to the smallest off changes in ignition & AFR...but now she starts first time & runs like a dream.
Eddie.

I did some experiments today. First, i changed the squirt of injector from 2 for cycle to 3 for cycle, and this seemed to helped a lot having a smoothest ride.
Than i had to re-tune it, i did some better tuining, and i'm quite satisfied for now... I tried quickly with the alpha-n but i would need to change completely the ve table. I see also the "ITB" way, that still uses the MAP sensor, and the car run quite fine with that mode too. But then i made the spark dirty, the map sensor hose disconnected and i did not realized it quickly, so i sprayed a lot of fuel in next days i'll made some other tries, but for today i god quite good resoults...

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Excellent, great to hear good progress made what it's all about. Thanks for your input Eddie, makes it all worth while. Keep us posted Andrea.

Martin

Cleaned sparks and did some more tuning
I'm still using Speed Density... but now the car is working so good! Seems strange, but just chaning from 2 squirt for rpm to 3 changed a lot.
Wideband is working and correcting if needed, Accelleration enrichment is doing it's work, and pedal respone is good for a "fast-road" car... and clutch is trying to slip after 4500 rpm ^^'' so some power is there... need to going for the good one, but not needed fast, I'm not going to race it for a while.

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Great that you got to an answer Andrea. I think part of the problem is less the electronics, but latency time in the software combined with the sensor input speed of response. Probably more driven by the speed of response to transient of the MAP sensor, with a time constant running into significant ms time frames, and frequency response at most a few kHz. Most of the sensors we use are thin film strain-gage with larger diameter diaphragms and deflections with pressure, a piezo electric would be better but suffer from drift and thermal inaccuracies. There is another method you can try or augment what you have already done, and that is ref the fuel reg to pre throttle plate, it will then never see high engine vacuum, and so will not see rapid transient change (high engine vacuum to ambient pressure) that will be modulated on to the fuel rail - this is my method. You then just make corrections to your fuel table, and it will look very flat in the partial throttle low torque regions. Just a thought

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Great that you got to an answer Andrea. I think part of the problem is less the electronics, but latency time in the software combined with the sensor input speed of response. Probably more driven by the speed of response to transient of the MAP sensor, with a time constant running into significant ms time frames, and frequency response at most a few kHz. Most of the sensors we use are thin film strain-gage with larger diameter diaphragms and deflections with pressure, a piezo electric would be better but suffer from drift and thermal inaccuracies. There is another method you can try or augment what you have already done, and that is ref the fuel reg to pre throttle plate, it will then never see high engine vacuum, and so will not see rapid transient change (high engine vacuum to ambient pressure) that will be modulated on to the fuel rail - this is my method. You then just make corrections to your fuel table, and it will look very flat in the partial throttle low torque regions. Just a thought

thanks for the suggest, it seems interesting, i'll make a try soon !
for the MAP sensor, i'm using the integrated MS one, wich is a 0-3,5 bar.

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Well I’ve been a bit stuck waiting for parts combing back from machining to get on with builds.. they may come through but looking unlikely before the break, these are the final balanced rotating and reciprocating assemblies for JIL and Swiss Chris builds, detailed further up the thread. I’m also waiting on the roller cam test profiles due to machine issues… So in the meantime I have been getting on with some other stuff, mainly associated with turbo builds..

If on a tight budget, and needing to use the OE waste-gate assembly, then as below for Cedric’s turbo you can eliminate much of the restriction, OE discharge is 1.9” diameter into the 2.5” down pipe. So bolded up to the face plate that is soon sorted:







Flipped over to bore out the back:



… and we’re nearly done, so hand blending work around the waste-gate discharge to do.





But more fun than that, I’m building a hybrid single turbo setup for 500hp for JIL at some stage. It has taken a while to do the research into the component parts (turbine and compressor wheels primarily) that would fit our needs specifically, track requirements, gearing etc. So for a bit of visual amusement, here’s the core parts going into it, but by way of comparison an OE 2.5ltr compressor cover beside it’s engine compartment replacement big brother…

I am a total novice on turbo engines. But I am interested to learn.

So my question is, wouldnt the inertia in such a big turbo make it laggy? I guess on a track car that may not matter if you can always keep it on boost?

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Absolutely, the race series requires if original set up was single turbo, the car can only be appointed as such albeit you can change the components. Hence, dictated, otherwise I would have gone, and had initially planned to go twin. The dual large intercoolers were then chopped and welded into one... So yes, you are dead right, so then it was choosing the right components to a) flow the necessary air to support the power level, b) good aerodynamics c) turbine that will extract the necessary energy to drive the compressor efficiently, hopefully with minimal weight... d) reasonable cost and DIY rebuild technology.

I searched through the hot side first as it is not well documented by the various manufacturers, possibly deliberately, and is not as easy to analyse as the compressor side where maps are relatively easy to use and available - published for nearly every compressor wheel out there you can find.

So yes the large single turbo is a compromise, and in an effort to reduce the absorbed energy from the turbine, the compressor is the smallest and lightest that will support the flow, and the deliberate use of a very large cover - I haven't worried about packaging this in the engine bay, that's Lee's problem However it comes with a characteristic that pressure ratio will rise slowly and then climb very quickly indeed. Modern electronics and ecu setup is going to be the control on that, if necessary fuel dumping and excessive late timing can be used to get it spinning off it's sweet zone... I will take some effort, but should be fun. I did also mention the gearing, and this has been deliberately chosen with final drive and wheel rolling diameter to keep the revs up, and peak power has been pushed past 7000 for this reason.; the engine is also 3ltr.

Martin

if necessary fuel dumping and excessive late timing can be used to get it spinning off it's sweet zone

Home grown anti-lag???

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...

sputter sputter bang... yep, will be giving it a go

I would appreciate input. I have the start of a PRV simulation and would appreciate any feedback and clarification on exact geometry. We estimated the following:
1) Port diamter, at the head and at the valve seat
2) Rocker ratio and cam lift (1.5?)
3) Cam center line (108?)
4) Cam profile / lift
5) Cfm of the carbs









Based on my discussion with other PRV guys the trends of the results look correct but before I proceed further I would like to get a group confirmation the input data looks correct. I will be looking for the 2.8 and 3.0 data next so if you have that I would appreciate the help.

Regards,
Brian

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Hi Brian, great to see you are progressing with your engine simulation, and also that the larger inlet and free flow exhaust ties out with practice.

I think it would be good to give some background to your project A310, as this is what the majority of the members on here will be interested in, and there are some very experienced guys doing restorations that I'm sure would be good to hook up with. In particular, JohnB on here has a 2.7 or 2.8ltr (it's an 88mm bore anyway), that he is currently restoring in a very nice A310 and that would be interesting to share as he wishes to stay OE looking as well. So it will be interesting to see the results.

I know you have put up some information in the following links with details of the car, so I’ve put them here so people can follow:

http://xwebforums.org/archive/index.php?t-15295.html

http://alpinerenault.online.fr/outils/f ... =9&t=26427

For those that want to follow the engine discussion, then Brian has placed them over here as well, so be good to drop in and join in folk:

http://alpinerenault.free.fr/outils/for ... =9&t=28109

http://dmctalk.org/showthread.php?5960- ... mation-PRV

http://forums.turbobricks.com/showthread.php?p=4437588

Good stuff,
Martin

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Brian,

Whilst I think of it (noticing the DCNF ref), the DCNF carb, what values are you using to simulate that, and is that with the manifold - is it a straight CFM number? I presume that was taken from measurement, do you have 40 and 45? I'm thinking of going back to DCNFs on my X19 simply for the look, and was going to hook up a couple of 45s. I do have both 40, and 45, what is your experience and recommendations?

Thanks,
Martin