Finally Mapped...

[Rippthrough 98]

Overall yes I am very happy with their service and especially expertise. I have a few issues that i'm not going to expand on here. It's a shame we ran out of time, I was an hour late and that couldnt be helped. No time left for cam swings, trumpet changes and further fine tuning the map. He did suggest it's worth coming back in a few months for a smaller follow up session, which will be needed to optimise things further.

 

There may well be a fair chunk more midrange to come then, going by other people's results from playing with trumpet lengths combined with timing changes.

[smckeown 1]

Nice peak but to me that curve seems a little all over the place... I am assuming that once the cam timing is done that will smooth out somewhat? Or is that to be expected with a proper lairy cam?

 

Yep you guys'n'gals are right. I was more referring to peak torque and not the curve itself. The curve does look a bit unusual. I didnt get the drive it a lot last night, it was dark, i was nackered as it was 1am, it wasnt legal, so it was only a few minutes up and down some quiet roads, but it really was fast so I was happy

 

When it's MOt'd, I can do more testing to see if that torque curve effects the power delivery through the rev range.

 

Then I'll try and do some 0-60 and 1/4 mile testing, anyone got one of those GPS dashboard machine thingy they can lend me ??

 

I'll email SteveG to see what he says about the curve

 

Hopefully DB will comment, as the dive of power over 6500 unexpected, we were expecting it to climb and climb, thats why the milder cam was chosen. Dave ?

Edited July 25, 2006 by smckeown

[16v205 9]

Thats a great looking power graph, that'll be fast on track especially as it shouldnt suffer with oil surge anything like the 16v engine's.

Are you going to Cadwell next week?

 

Rich

 

 

In reference to the power dropping off before 6500rpm.

 

Who set up the cam timing? If it was a little too advance the cam will peak before you'd want it to. Retarding it slightly should move the power further up the rev range.

[smckeown 1]

cheers regarding the advice, I was thinking of experimenting, and thus started this topic

 

Dave did the timing

 

No not at cadwell, busy next few weeks getting it road legal and finishing a few bits and bobs. Planned track days in my sig

[pug309twin40s 1]

well done mate.

 

sounds like a cracker. good to show 8v's arent dead yet.

[petert 586]

Yes, a good result. You might be able to move the powerband up a few hundred RPM, at the expense of the some torque, but you won't see it climbing to 8000.

[smckeown 1]

That's the stranmge thing, we we were expecting it to rev until the end.

 

Here's why:

 

1 - Uprated valve spring system, if it's not going anywhere near 8k revs then why add these in ?

2 - Experience from CraigB's exact same head - here's what dave said about the cam coice of my head "In the end, for the main reason that it was a known quantity that had just been tested in CraigB's engine, the choice ended up as a Catcams 4900340 which has 255 degrees duration at 1mm lift and 12.25mm total lift. This has a useable power curve from about 3000 rpm to 8000 rpm"

 

So while I am very happy with the torque, I really am impressed how dave and the mappers have maximised torque, but I am slightly miffed based on the above points, why the power drops so early.

 

The amount of torque is a credit to dave maximsing the effociency of the bottom etc.

[petert 586]

I used to run the Group A cam, which is basically identical to the 4900340, along with lighter big valves, double springs etc. It would rev all the way to 8000 if you let it, but 7500 was definitely the end of the useable power range. Plenty of people will say their motors rev to 8000, but very few will actually be making hp up there.

[Dom9 2]

I must admit, initially, to not being overwhelmed by the headline power figure, but the graph comparing your results to a standard Mi shows just how much more power you have at lower rpm and the area under your curve is a lot, lot bigger than the area under the superimposed Mi curve!

 

So, I guess congratulations are in order DB/Sean! :-)

 

However, it would have been nice to see a higher headline figure, like PeteF's engine... I know that the area under the curve and the driveability is the most important factor, as well as the goodly amount of torque you have, but it would have been nice to break the 100bhp/l value, which I thought Dave was aiming for... Wasn't that the case in some of the early threads?

 

At 87bhp/l it's better than most people achieve and I guess you are on a largely standard bottom end... But there are certainly engines producing more... Maybe they don't have the same area under the power curve as you do, and for all my hatred of pub talk power figures, it would have been nice to see something in the 180-190bhp category.

 

This certainly hasn't been a cheap build and there are a fair few cars running circa 150bhp on carbs, so I (IMVHO) would have hoped to have seen all that work produce more than 10% more...

 

But, that's possibly splitting hairs! You are obviously very pleased with it and that speaks volumes after how frustrated you have been with the build at times. I can imagine that if it had not exceeded all expectations you would not be a happy boy, so well done! I reckon your car will prove to be a real monster on track!

 

For what it's worth... The power does seem to die off a little early and those peaks and troughs in the torque curve definitely look like they might be ironed out by some induction length trials.... Suck it and see basically! Hopefully, once the rings are nicely bedded in, you have played with the induction and checked the cam timing, a small re-map could be done to see if you can squeeze a couple more pub horses out of it!

 

All in all - A good job well done! It will be interesting to see what sort of machinery you are chasing at the trackdays! :-)

[niklas 1]

Would be interresting to hear DB's view on the result. Was it as expected? How did the late changes of cam choice affect the outcome?

How can the dips in the power curve be cured? Mapping? Cam timing? Other modifications?

[smckeown 1]

which I thought Dave was aiming for... Wasn't that the case in some of the early threads?

 

Initialy that was the target. But, based on feedback from Craigb's head, dave believed we would run out of revs that the budget bottom could cope with, so he revised his choice from PT28 to the Catcam. So the power target went down to a discussed ~175bhp. I am of course scratching my head thinking why the graph is so different from craigb's, i.e. why does it tail off after 6500 etc.

 

For what it's worth... The power does seem to die off a little early and those peaks and troughs in the torque curve definitely look like they might be ironed out by some induction length trials.... Suck it and see basically! Hopefully, once the rings are nicely bedded in, you have played with the induction and checked the cam timing, a small re-map could be done to see if you can squeeze a couple more pub horses out of it!

 

Yeah I wil lsave up and go back, but it would be good to get dave's opinion. I have also emailed Steve Greenauld to get his opinion on the wavey torque curve and tailoff to see what he thinks

 

 

Would be interresting to hear DB's view on the result. Was it as expected? How did the late changes of cam choice affect the outcome?

How can the dips in the power curve be cured? Mapping? Cam timing? Other modifications?

 

Hopefully he's number crunching and will reply soon with his wisom

Edited July 26, 2006 by smckeown

[smckeown 1]

Here's the torque comparison with an mi16. Havent got the 1.9 8v graph yet, will update this graph when I have that extra data

 

 

So I was right when I said it felt faster than an mi16. This car is also about 30kgs lighter than my old mi16 track car

 

Here's the % changes:

 

2000 -23.6

2500 -8.2

3000 1.3

3500 0.6

4000 6.4

4500 5.2

5000 8.6

5500 7.0

6000 3.6

6500 5.3

 

Sean

[Craigb 2]

I am of course scratching my head thinking why the graph is so different from craigb's, i.e. why does it tail off after 6500 etc.

 

Maybe a starting point is to look at the 2 engine configurations

 

 

Sean vs Craig

Bodies vs Plenum

4 branch exhaust vs Std Manifold

CR ? vs CR?

Cam Timing ? vs 106 Deg's

KMS vs Emerald

New engine vs 25k since liners and pistons renewed

 

Possibly other factors.

 

I would be dead chuffed with all that torque, especially as low down the range as you are getting .

 

I would say well done DB a quality result

Edited July 27, 2006 by Craigb

[smckeown 1]

Maybe a starting point is to look at the 2 engine configurations

Sean vs Craig

Bodies vs Plenum

4 branch exhaust vs Std Manifold

CR ? vs CR?

Cam Timing ? vs 106 Deg's

KMS vs Emerald

New engine vs 25k since liners and pistons renewed

 

Possibly other factors.

 

I would be dead chuffed with all that torque, especially as low down the range as you are getting .

 

I would say well done DB a quality result

 

Let me repeat i'm delighted with the results, as I stated very early on, so people shouldn't read that I am not happy with it (if they are).

 

I am still surprised that it tails off, as I am led to believe a tail off normally means it's not breathing as well, especially when compared to a head where mine breaths better (TBs).

[Sandy 191]

I must admit, initially, to not being overwhelmed by the headline power figure, but the graph comparing your results to a standard Mi shows just how much more power you have at lower rpm and the area under your curve is a lot, lot bigger than the area under the superimposed Mi curve!

How do you figure that? Taking the factory Mi16 figures against the graph posted at the start of the thread, we have:

 

RPM----Mi16----Sean's----%difference

 

2500----56----49----14% less

 

3000----70----68----3% less

 

3600----76----76----0%

 

4000----93----94----1% more

 

4500----108----110----2% more

 

5000----127----135----6% more

 

6500----160----163----2% more

 

So from the above, you can see that the factory Mi16 is in fact more powerful at lower rpm and only gives anything meaningful away to this engine over 4900-5200rpm. We have to allow error for dynamometer differences of course, but that can swing the result in either direction.

 

It's a reasonable result for a tuned 8v, but to say it's more powerful than a regular, healthy Mi16, is frankly misleading!

[Jonmurgie 2]

This should help a bit.. official figures in a graph:

 

[Dom9 2]

How do you figure that? Taking the factory Mi16 figures against the graph posted at the start of the thread, we have:

 

RPM----Mi16----Sean's----%difference

 

2500----56----49----14% less

 

3000----70----68----3% less

 

3600----76----76----0%

 

4000----93----94----1% more

 

4500----108----110----2% more

 

5000----127----135----6% more

 

6500----160----163----2% more

 

So from the above, you can see that the factory Mi16 is in fact more powerful at lower rpm and only gives anything meaningful away to this engine over 4900-5200rpm. We have to allow error for dynamometer differences of course, but that can swing the result in either direction.

 

It's a reasonable result for a tuned 8v, but to say it's more powerful than a regular, healthy Mi16, is frankly misleading!

 

Ummmmm... Are we reading the smae graph? The one that Rippthrough posted further up?

 

It shows Sean's engine giving more power at all rpm's... And around 25bhp more at 5000rpm...

 

Am I confused? I can't make out the graph too well on my computer!!

[smckeown 1]

I plan to graph the mi16 power and mine together in detail tonight, in the same fashion i did the torque last night. I'll also add the XU9JA torque to the graph i produced

[Jonmurgie 2]

These are the torque figures going from Sean's original graph and the graph I post just up there (converting the torque figures from NM to ft-lb):

RPM - Sean /Mi16 /+ or -

2500 - 103 / 116 / -11.2%

3000 - 118 / 120 / -1.6%

3500 - 115 / 116 / -0.5%

4000 - 123 / 120 / +2.5%

4500 - 128 / 124 / +3.3%

5000 - 143 / 132 / +8.4%

5500 - 142 / 131 / +8.4%

6000 - 136 / 129 / +5.5%

6500 - 132 / 127 / +4.0%

[smckeown 1]

These are the torque figures going from Sean's original graph and the graph I post just up there (converting the torque figures from NM to ft-lb):

RPM - Sean /Mi16 /+ or -

2500 - 103 / 116 / -11.2%

3000 - 118 / 120 / -1.6%

3500 - 115 / 116 / -0.5%

4000 - 123 / 120 / +2.5%

4500 - 128 / 124 / +3.3%

5000 - 143 / 132 / +8.4%

5500 - 142 / 131 / +8.4%

6000 - 136 / 129 / +5.5%

6500 - 132 / 127 / +4.0%

 

wierd, if you look back one page that's what i posted last night, the graph with the figures below

[Sandy 191]

Ummmmm... Are we reading the smae graph? The one that Rippthrough posted further up?

 

It shows Sean's engine giving more power at all rpm's... And around 25bhp more at 5000rpm...

 

Am I confused? I can't make out the graph too well on my computer!!

I took them from the original graph, Rippthrough's was a different for some reason?!

[JERAM 0]

good results sean, if it drives good then thats all that matters.

 

playing about with the timming and trumpet length may well iron out the flat spots

 

 

here is a set of figures from a totaly standard MI running carbs that took hours to get rid of the flat spot's

 

though comparing a 8v to a 16v is quite pointless

 

 

[Rippthrough 98]

I took them from the original graph, Rippthrough's was a different for some reason?!

 

because I used MSpaint just to give a quick look at the relative shapes, someone didn't read the disclaimer, the bottom end is a little lower than it should be

Edited July 27, 2006 by Rippthrough

[Jonmurgie 2]

wierd, if you look back one page that's what i posted last night, the graph with the figures below

I think I got confused when Rippthrough posted those other figures which turn out to be Mi! At the end of the day you won't be getting as much power as an Mi and that was never your goal so I'm not sure who/why it was being comapred with that!

[smckeown 1]

At the end of the day you won't be getting as much power as an Mi

 

You sure ?

 

New graphs: