First off, sepc of the engine:-

2.1 Pinto
10.7:1 CR
Piper OHC134 High torque cam
3 angled valves but std size/flowed head.
4-1 stainless manifold
45mm tapered throttle bodies
MS v3 ECU running MS Extra code

Now, I have a "conservative" spark map whilst I've been dialing in the fuel. I'm now happy with the fueling and I'm hitting the AFR target afr's I;ve set. Cruise econimcally at about 15:7:1 then ramps up to 12.6:1 at full throttle. No hesitation and starts and warms up excellently. So now it's time to move onto the spark map.

Now, I have no experience of tuning spark so the first thing I'm going to do is make some det cans but even if I do, I'm not sure I'd know how to use them. So, this is my current spark map:-



It aplha-n - i.e. TPS vs RPM.

Does anyone have any suggestions of any amendments to it BEFORE I get the det cans on it? I.e. are there any points where it's obviously way off? One thing I have noticed on the car is that the engine pulls really strongly at low rpms but then seems to tail off and seems rather flat at above 4500rpm, even though the afr's a bob on at that point.

All advice welcome and greatly appreciated - might even pop down to MSD at the weekend to see if they fancy taking the task on.

 

There is nothing wrong with the basic shape of that, really, although the slight dip in ignition on the 6K line will probaby cost you a couple of lbft, as it should take more timing not less than on 55, but its only a tiny dip anyway.

Personally I will be surprised if it responds well to anymore than 40 degrees of ignition too, so I would imagine your going to need a hotter cam if you want it to pull harder at higher RPM

 

PS

Please can you post the fuel map, should be very obvious from that if the cam isnt hot enough (or head porting not big enough etc, or other reason for an excessive drop in VE)

 

This is a fuel map from last week - I have since blended/smoothed it out a bit and worked on the areas rarely seen (high rpm/low tps - high tps/low rpm) but it gives you a general idea of the curve - it's not a million miles away from where it is now - hope it gives you enough info Chip - thanks for the help btw.



One thing I'm thinking is that It's a high torque cam - low duration/loads of lift. Maybe it feeling strong at low rpms/flat at high rpms is just how it should be.

 

Pintos seem to like alot of ignition advance due to their old 2 valve head design.

The flatness at high rpm may be down to lack of ingnition advance or as chip says it could be your cam choice.

Your det cans will not be much good on a n/a engine as i doubt the ideal ign advance will be det covered.

The only real way to tune ign advance is on a dyno where you can find the lowest advance figure that alows you to achieve the most torque at each point.

 

Hmm, alot of RR operators don't like MS due to there being some right dodgy installs out here. I don't know anywhere local to me with an RR anyhow and as it;s in a Westfield, I don't fancy driving any distance to get to one.

Would timed runs in 4th gear help me tune in the spark map? I could do something like that my my Gtech.

 

difficult to see the effects of an individual load site when timing runs, so although it may help if you move the whole curve up and down, it is unlikely to allow you to optimised the shame of that curve.

Can you show me an AFR plot too?

Its just that based on what you have said about helding a steady 12.6 AFR and the power dieing off over 4500, that fuel map isnt what I expected to see at all, I was expecting to see the rate of fuelling decline as you approached higher rpm, to signal a drop in VE.

 

I'll have to get the AFR map off the laptop when I get home - I'll post the AFR target, spark map and VE table all on one post when I get home this afternoon.

Thanks for your help again

 

IF it still managing to consume air per cycle well (ie with a decent VE) figure at high rpm (which will be the case if that fuel map is holding a steady AFR up to 6K) then you can certainly try more advance, but 40 is already a lot of ignition so the gains are going to be minimal probably.

If that happens, higher CR might be the way to go!

 

Chip he is only running 40 deg at light throttle high rpm.

I think you could add at least 5 if not 10 deg to your full throttle high rpm stuff.

 

I go open loop at 100tps adc so I'm only putting in around 30 deg of advance around that point. On these throttle bodies, there is hardly any MAP change between 100tps and 220 tps - You can see between 130 tps and 220 there is a minimal VE increase. To keep the engine at steady @ 5000rpm needs about 75tps - that's 35 deg adavnce on my map.

EDIT: - What Garage19 said


By the way - it would be really hard to hear pinking in a Westfiled I would imagine - that's why I've been (I think) cautious on the ignition map so far.

 

Yes fair point, he could see gains at higher throttle angles with a flat ignition value of 40 for all points probably.

 

Its fine if you use det cans that have decent ear defender type headphones to block out other noises.

 

So would changing the map to something like this be appropriate?

 

Yep, give that a try. You should be able to hear the difference in the tone of the engine.

Let us know if it feels less flat.

 

Thanks - I'll give it a try at the weekend and post back the results

Thanks for the help

 

If you are miles away from det currently, then yes that probably will work well, make sure you use det cans though, even though these old 2v motors can normally go up the road detting their tits off with no damage anyway!

 

Cool - thanks for the advice - I'll plan a trip to B&Q tomorrow to buy the bits to make a set of det cans and use them when I upload this map

 

Cool, good luck with it

 

I think C/R is to low. From what i read you should see max power at around 32 advance.

 

More important is seeing peak cylinder pressure at about 14 degrees ATDC, but thats hard to measure.


I agree with you on the CR though.

 

CR too low? It's already way up on stock.

 

I think your CR is fine for pump fuel.

Not sure why they think it is too low?

 

Too low for optimum torque at high rpm i meant if he wants to make more power up that end.

 

From what i remember about pintos they have a stock CR of 9:1 so 10.7 is a fair raise already and because of his mild cam the actual dynamic CR will be quite high.

 

I'd probably lean it off a bit from where you're at. On the top line start around 13.2:1 and end up at 12.8:1 at the red line.

 

The figures at the top right off the map do look excessively high considering its running a high torque cam, especially the very last two. The highest figures should be around peak torque/peak ve area which will no way be at 6500rpm

Do you use megalog viewer? could you post a log/screenshot of a full throttle run in 3rd or 4th that shows afr?

 

Right - had a good session out yesterday with my home made det cans and a friend driving the car whilst I was tuning and listening for det. 1st thing is I'm miles away from any kind of det - didn't really notice any until about 44deg BUT we could already feel performance dropping off. With a fair few 3rd and 4th gear pulls and a g-tech (and half a tank of fuel), this is where we ended up and it feels really strong and smooth - very happy with the results. Re-visited the fuel map as well and made a few tweaks. Thanks for the advice guys

 

Sounds promising, and always nice to have that much head room DET wise.

 

Quick update - RR'd at Protec - 142 @ the wheels.


Think I need to find another rolling road!

 

Were you expecting different to that then?

I think that sounds fairly good personally.

 

180bhp approx @ the flywheel? Not a cat in hells chance on a Pinto, RR must be way out. I couldn't even go in the dyno shed and no graph - just a printout with one column of numbers - rpm vs whp - no torque measured. Could have done the pull in 2nd gear for all I know. They insisted it was correct though :-(

Was expecting 155ish at the fly - 120ish at the wheels. R