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Discussion Starter #82 (Edited)
You'll make me blush... Cheers guys, really nice of you to say :)

It's interesting to note that the 121 RWHP it made on that day is about what a very healthy stock motronic TS will do on the same Dyno... So no amazing leaps peak HP there..

but ....

The Dyno day was very interesting - I posted up a little vid of youtube with the live Megasquirt log playing during the run
.

Interesting comparing the bursts of rich soot out the exhaust with the Air Fuel Ratio waveform as it travels through the fuelling map. You can see corresponding dips and peaks in the torque curve to match here.


dynoresult by Mott Scurray, on Flickr

For this run, I left the car on static fuelling according to the maps I'd been working on with the AutoAnalyse function of TunerStudio. You can see the Torque and HP curves have ripples as the AFR fluctuates...

The main reason the AutoAnalyse hasn't settled on an optimum tune here is the way I have my VE bins setup, and how the ITB mode calculates load to select those bins for fuelling. I still have some issues with it 'hanging up' in a few load bins - meaning the system is trying to tune, for example, 25% load and 30% load in the same bin, it keeps readjusting and never settles.

I've since been running the car with EGO Correction / Incorporate AFR activated - so it's tuning on the fly itself (basically the same as long and short term fuel trim in modern car speak) which is giving much better results as it adapts on the fly.

I did a telemetry overlay video
of a recent trackday showing the AFR - when it's under load, it keeps the fuelling mixture under very tight control to match the AFR Target table in the system

Festy's point about additional horsepower relates to this - I perhaps have my AFR targets set too close to Stoichometric (14.7:1) air fuel ratio - this is for best combustion of the mixture - I will need to do a bit of a comparison at slightly richer mixtures to see where the best torque is made. You can than also try adding a little extra spark advance in those richer areas to see if any more tiny little horses are hiding in there...

I think I make it sound a lot more complicated than it actually is.... :)
 

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Discussion Starter #83
Oh - forgot another daft thing I did - on the dyno results, just past the peak HP and Torque at ~5900rpm - you can see both start to ramp downwards until the car hits the spark limiter.

This is because I had a very conservative spark retard soft limiter setup at 5900rpm - it started retarding the ignition incrementally up to 10deg. at this point. I put this in last year at my first track day to stop me getting too ambitious - it has the effect of making the engine feel like it has peaked and encouraging you to change up to the next gear.

You can see the effect on torque very clearly in that ramp down at the end of the curves.

So the next dyno run will be interesting - I've removed that spark retard, and now have a 4/5 spark cut at 6700 and fuel cut at 6800 limiter. the engine feels like it has topped out at around 6500 now, but doesn't feel like it loses any power from there up to the limiter...

Empirically I'm now catching up Trad's green super on the straights at our track events where I wasn't before...

Really love being able to fettle all this stuff in software at the moment.
 

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That ties up almost perfectly with my recent result with my GTV TS: 92 kW (or 122 bhp). This engine is totally standard and 220,000 odd km on it, with just a BBR chip and bigger exhaust from the 2-1 collector to increase the neds.

Years ago, I achieved 106 kW (141 bhp) RW with a virtually stock engine in my GTA-R, but just 45mm dellortos, GTA trumpets and 4-1 headers.

I just went back and quick re-read about your build. Some similarities in the engines I am in the middle of building and yours (i.e. head that was particularly hard to remove, front nut that needed a 4' breaker bar etc). However, I am putting Nord rods in and have done some more extensive porting, valve and seat work.
 

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Discussion Starter #85 (Edited)
One thing I always have to remind myself is that Dynamometers are at best only baselined against themselves - and typically only baselined against themselves on the same day.

Definitely putting the nord rods in the my next iteration, and my porting effort was really just a cleanup. From memory I was pretty conservative with what I removed from the noses of the valve guides too.

What else did you do to the valve seats ? I thought I was fairly agressive with that 70 deg. cut down the throats.

I didn't do any work to the valves themselves - ran out of time even though JK's book had some juicy tips there.

I've talked to quite a few different folks on what output you can reasonably acheive from a mostly stock TS. My current heuristic (which probably parades my ignorance more than anything else) is this:

rwhp / chp (Wheel Horsepower to Crankshaft Horsepower Guestimator)

~120/150 well cleaned up stock engine with light porting and good intake/exhaust

~130/160 with agressive porting / maybe bigger intake valves / excellent intake runner length and airbox.

~140/170 with nord rods and some bottom end balancing / windage tray etc

~150/180 aggressive cams with higher lift / pocketed pistons

~165/200 with bottom end to take higher rpm, maybe injectors / higher pressure fuel to feed it

Again - just my rough thoughts...


Speaking of intake runner lengths - have you seen how the Yamaha R1 does it .... an evil plan germinates...

here
 

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1.25 inlet / 1.75 exhaust wide valve seats right out on the outer margin of the valves, 70 degree throating as you have done, then opened upthe bowl so that the 70 degree cut is merely to break the transition from port to seat. Inlet valves back cut so that the seat margin is only + .5 on the contact area. The shrouding on the inlet combustion chambers relieved. I also have opened up the ports as per the diagrams in JK's book (particularly in the valve guide boss area, and where the oil drains passage is. I also tend to broaden the top of the port either side of the (tapered) guide.

Looking for 105 - 110 RWHP (with some hand made headers).

TS Head
 

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Discussion Starter #88 (Edited)
Love that intake runner work you did...

I actually cut mine up into individual runners to see if I could use them as part of my intake - they look just as bad inside as yours did... I'm going to have some alloy or thin stainless tube mandrel bent instead (and somehow find room for those R6 popup runners...heh heh)

Will be really interesting to compare notes as we go I think !

Cheers,
 

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I'm slowly developing a plan to move my loved 1750 Giulia Super to a Twin Spark with either carbs or motronic or custum injection.
Reading this topic and looking at the results in HP I wonder if I should stay with the standard injection (which I think is rather bulky etc but look very efficient in output) but this would spoil the joy a bit (but save a lot of work) or go all the way with seperate trottle bodies form Suzuki GSXR 750 or BMW K1300 for example.
But what will be the result difference in gross power difference?
I'm puzzeled a bit now.
Thom
 

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Thanks !

the Spica piece is hollow inside - maybe 20mls, it's more likely the 1.5m vacuum line to the ECU in the car that's forming a plenum to dampen the pulses.

Looking at the composite logger - MAP seems pretty clean...

The ITB tuning mode in the MS3 I'm using takes a bit to get your head around - but a few learned mates are pointing me in the right direction :)

A good friend is running the AH ignition and loves it. I didn't realise they were motorcraft coils - they are highly recommended by the tuners in the states I hear.

I was using the Motorcraft EDIS wasted spark coils (without the EDIS) without any probs, switched to a pair of the more compact DIYAutoTune 4 towers for a neater install, then moved them from the intake to exhaust side to tidy it up for the airbox, but I'm going to fit some COP units from the same GSXR I sourced the ITBs from to really tidy things up. (and because I'm silly that way) Will still run them wasted spark in serial pairs off the same Bosch 211.

The pencil coils are Denso 129700-4150/4400, about 3.5 inches from the top of the plug ceramic to the bottom of the electrical connector on the top. Shortest / smallest diameter plugs I've found so far.

Amazed at how many tuning options the MS3 + MS3X expansion board gives you.... fantastic stuff for so few pennies.
Hi Scott!
What kind of fuel injectors and at what pressure are you running?
It seems that TS stock injectors (0-280-150-702, 18 LBS/HR, ~190 CC/min) are really undersized for the factory claimed power output @ 3bar of pressure. My engine rebuild (head ported, but otherwise close to stock 155 type engine) is close to finished and I have a set of bosch type 3 injectors (21.35 LBS/HR) laying around. They seem to be a better fit to achieve the claimed hp and maybe a little more on the stock motronic.
 

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Discussion Starter #92
Hi ! you've reminded me this thread is well due an update :D

I know what you mean re the injectors - I'm still runing the stock injectors and pressure - from memory I thought the standard injectors were good up to ~ 190hp at the upper end of their pressure rating... (memory is getting hazy there) so I was only going to upgrade them if the megasquirt was having to run excessive duty cycle at high rpm and load to keep the AFR right.

I haven't had an issue with them so far, but the current engine tune is only ~ 175hp. Engine is coming out for new pistons, camshafts and a couple of other mods shortly which should get me up around the 190hp mark. If you run a wideband O2 sensor you can keep an eye on AFR at high rpm and load - that might tell you if you need to up the injectors or not :)

I think the only risk of running the larger injectors is if they might make idle control a little trickier - the bigger the injector the less granular they can be at idle. I don't think a jump from 18 to 21 lbs/hr is going to be a massive issue though. The motronic is batch fire injection which contributes to that a little as well.

Are you going to run the stock motronic intake plenum and runners ? if you've ported the head and maybe opened up the valve seats a little - the next restriction can sometimes be the ID of the intake runners - they get pretty narrow in places :)

When do you think you'll be firing it up ?

Cheers

Scott
 

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Hi Scott!
The engine is still in peaces - plan is to finish it until end of August. I have a trackday scheduled in early september, so I'd like to finish it until then.

Head porting is finished, modified valve guides going in and hopefully also valve seat will be reground this week.
I'm still waiting on crank balancer, but as I haven't received rings yet, bottom end can't be assembled yet anyways.

The intake runners have also been enlarged and matched to the head (as you know, ports actually don't line up from factory)
This is the intake runner and most of the material removed.


Matched ports to intake:




The intake manifold itself will also need some attention - the plan currently is to cut and weld the aluminum intake from 155ts engine I have (FWD intake can't be used in a 75 without modifications as it is well above hood line and 164ts has plastic intake - so it can't be easily modified).

To see if motronic can handle the increased flow and bigger injectors, I've bought a wideband controller (SLC free from 14point7), which I plan to use with a logger of some kind, but as I don't have any experience with ECU tuning I'm trying to learn as much as I can at the moment.
 

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Btw. the motronic I'm going to use (m1.7 from 164ts super, series 2) has 2 separate injector channels, so I'm not entirely sure if it works the same way as 75TS, which has a common + and - for injectors, so only one injector channel.
 

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Scott:

A few pages back you posted your initial spark advance table whereby all values were the same of each load value. Only rpm based. Have you modified that table? If so, can you post it, please?

Thanks for posting your work and findings,
 

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After just rereading the thread the x-time i've been wondering whether the 38mm throttle bodies may (have) hindered power beyond the figure you had. Could that be?
Does anyone here know how ITB sizes relate to carb throttle sizes? From reading online 38mm (in your case) would be close or equal to a carb with a 38 venturi which wouldn't be smaller than a 45 carb with larger venturis which some guys here run with 150 hp+.
Quite frankly I'm wondering how the vacuum in the carbs for sucking fuel does hinder airflow vs ITB.
 

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Discussion Starter #97
Hi Allessandro, another great question ! The throttle bodies are straight through (well - there is a slight taper which is 38mm at the smallest) a set of 45 dcoe's with a 38mm choke will have more restriction due to the secondary venturi's hanging in the middle of the port - so the 38mm ITBs will flow better of course.

Because the ITBs and Injectors aren't dependent on air speed giving venturi effect to draw fuel - you have less problems with low speed air stall with larger bores than you would if you ran a set of weber 45's with 38 or larger chokes.

The other thing to remember even with an excellent Jim K style porting job on the intake ports, you are still faced with intake ports 38mm dia or lower (with a valve stem and guide in the middle of it) so going to a bigger throttle body doesn't help with flow.

What a bigger ITB (or 45 dcoe) gives you is a bigger butterfly valve - which can offer a snappier throttle response (or very sensitive throttle - depending on your definition)

This is a bit of a running argument I have with friends around which throttle body diameter to choose - some have insisted on going to 45mm ITBS (because Weber 45's right ?) and end up having to 'gear down' their throttle linkages to deal with the sensitive throttles - and also with air stall / bog down issues at lower RPM.

Just a couple of my thoughts anyway - more learned denizens of the forum may be able to shed a little more light on it :D

It's great fun working it all out though, isn't it !

Cheers,
 

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High Performance Math

Would say 42-45mm depending on where you want your peak tourque to be.
I can agree with the math here for TB as I have checked MANY different calculations online, and for ITB's I will be going with around 42mm, just because I want more airflow lower down in the range, and don't mind giving up a smidgen up-top.

Enjoy the calculator's they are fun.
Ian
 

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Discussion Starter #99
That's a great resource all on one site - thanks !

I think once you go bigger than the effective 'diameter' of your porting, seats, valves and lift area - you're adding snappier throttle with the larger butterflies (and maybe risk of air stall), but the head is still the limiting factor I guess.

If they're tapered though they might become effective intake horns which can be handy in a tight space :D

I love this stuff :)
 
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