Tuning issues w/ dyno data

[abec]

So my car now runs a programmable fuel system.

When it was being tuned the hp started getting jagged. My tuner wanted me to get the distributor checked out before I get it back on the dyno.

Then I got conflicting information saying that its normal and that the electronic distributors on the X are just about bullet proof, and that the coil is the weak link typically. Also that it should be expected that power band on the X should be jagged at high RPM's due to engine vibration.

The engine in question is reasonably modified, big valve head, 10.5:1 compression, stock cams, everything has been lighted and balanced.

I believe its safe to assume that my current dyno numbers are way below what they should be. I know that spending as much $$ as I have with out getting a significant gain is kind of a let down, so I hope with a leaner tune I can reach my target power I just don't want to blow the motor if something is wrong.

I don't have a JPG but I do have the graph data.

RunFile_001.drf: 88.69∞F 30.07in-Hg Humidity:27% STD:1.02 Average Gear Ratio:69.03

s RPM x1000 hp ft-lbs
0.28 2.40 N/A N/A
2.55 2.50 35.70 75.00
2.94 2.60 37.94 76.65
3.37 2.70 39.60 77.03
3.77 2.80 40.88 76.68
4.19 2.90 42.99 77.85
4.62 3.00 44.57 78.03
5.04 3.10 45.94 77.83
5.44 3.20 46.87 76.93
5.89 3.30 48.14 76.62
6.30 3.40 49.41 76.33
6.76 3.50 50.99 76.51
7.18 3.60 52.50 76.59
7.59 3.70 53.73 76.27
8.04 3.80 54.85 75.81
8.46 3.90 56.29 75.81
8.92 4.00 57.73 75.80
9.35 4.10 59.06 75.65
9.78 4.20 60.11 75.17
10.20 4.30 62.12 75.88
10.64 4.40 63.38 75.65
11.09 4.50 64.90 75.75
11.55 4.60 65.89 75.23
11.96 4.70 67.14 75.03
12.43 4.80 68.73 75.20
12.83 4.90 68.95 73.90
13.32 5.00 70.66 74.22
13.78 5.10 71.29 73.42
14.22 5.20 72.68 73.41
14.70 5.30 72.91 72.25
15.15 5.40 72.24 70.26
15.64 5.50 73.03 69.74
16.13 5.60 72.88 68.35
16.64 5.70 72.74 67.02
17.18 5.80 73.12 66.22
17.70 5.90 71.12 63.31
18.26 6.00 70.75 61.93
18.80 6.10 70.35 60.57
19.39 6.20 68.69 58.19
20.00 6.30 66.56 55.49
20.65 6.40 64.98 53.32
21.31 6.50 63.54 51.34
21.99 6.60 65.01 51.74
--------- --------- --------- ---------
MAX: 21.99 6.60 73.12 78.03
MIN: 0.28 2.40 35.70 51.34

 

[///Mike]

Huh???

Did you really mean to write "stock cam(s)"?

The few other details you provided sound like the basis for a nice stout street motor. You didn't say anything about displacement, induction, or exhaust, but a well built 10.5:1 1500 oughta make at least 100 RWHP.

Since you didn't give enough info to know the whole story it's difficult to guess where any problems might lie. But one thing is for certain-- a stock cam in a motor with a BVH is about like trying to feed a firehose with an aquarium pump. ;-)

///Mike

 

[TonyK]

The way I see it.

This car must have a stock camshaft, it isn't breathing as the RPM's go up. A stock engine runs out of breathing room around 5000 rpm. This engine is a little higher, possibly the big valves are giving it some added asperation. The compression would help as well at the bottom end. Take also into account that this is measured a the rear wheels and not at the crank shaft. So it is a bit better than stock I would say that he has gained 10 maybe 15 HP.

The camshaft has to be changed to get better numbers.

TonyK.

Grimsby Ontario Canada.

 

[abec]

Yes it still has the stock cams, along with stock exhaust.

With the haltech fuel management I was able to replace the stock air flow meter with a map sensor, so there are no obstructions in the intake. The intake consists of a cone filter and an aluminum 90 degree pipe.

 

[///Mike]

Well...

The cam and exhaust certainly aren't helping.

By induction system I was referring to the intake tract. Was the intake ported to match the BVH? If not, the intake charge will stall as it enters the larger ports in the head.

I have a book on cylinder head porting in which the authors talk about modifying the head on an otherwise stock Euro spec X. They wound up getting something like 85 RWHP just from port and combustion chamber work (they did not install larger valves). Like I said, a well built, well tuned 1500 oughta make at least 100 bhp at the wheels.

///Mike

 

[Black-Tooth]

Hey Wil... I agree with TK and ///Mike's consensus...

1. RWHP of 73hp *5800 rpm... if I read that right... is what I too would expect with your current set up.

2. A cam and header would allow this engine to breath a bit better but then again, I doubt if you would gain any more than another 10 to 15 RWHP.

BUT... 80 - 90 RWHP is what we would expect and MOST folks would generally be quite pleased with. I have a feeling though... that is NOT enough for you.

If so, then a turbo or supercharger for up to about 130 RWHP but I would be hesitent to say it would be very "streetable" or reliable. For more, a Japanese or Chyrsler engine conversion would probably be necessary.

 

[Rupunzell]

Curious, what was the rational for using a stock cam and exhaust on this project?

Bernice

Yes it still has the stock cams, along with stock exhaust.

With the haltech fuel management I was able to replace the stock air flow meter with a map sensor, so there are no obstructions in the intake. The intake consists of a cone filter and an aluminum 90 degree pipe.

 

[abec]

Curious, what was the rational for using a stock cam and exhaust on this project?

Bernice

The plan is to go turbo. I plan on bolting it up directly to the stock exhaust manifold then having an exhaust welded up, and using turbo specific cams.

Though at the moment this might not happen as quickly as I expected, so I am looking into NA cams as well as headers & exhaust.

 

[jake]

just a thought

If you go turbo won't you need to go back to lower compression? I'm no turbo expert but i'd suspect you might run into predetonation issues at 10.5/1

But I guess that would also depend on the amount of psi and air temps.

For NA system it looks like your almost there.

 

[abec]

depends on how much boost you want to run, and the type of gas.

You can run turbo on high compression at high boost with race gas or low boost (say 3-5lbs) on premium pump gas.

The plan is to have a copper head gasket that drops my compression to 9 or 9.5, that way I can run moderate boost on pump gas. This is done often in the VW 16v motors to drop their compression from 10:1 to 9:1 or lower when installing turbo kits. Other times they just install two head gaskets, but having a thicker copper one made seems more reliable.

I found more information about copper head gaskets here. http://www.headgasket.com/index.html
They also have the x1/9 on their product list already.

 

[EricH]

Graphed it, just for grins

Here's what it looks like:

Torque is really kinda nicely flat out to 5K

 

[abec]

Thanks! I need to go back and have them print out the actual dyno graph. It is much more jagged on the full detail graph then the data file they gave me.

I am use to high torque vw motors, but I do not think the fiat 1500 should have higher torque then hp :hmm:

Here's what it looks like:

Torque is really kinda nicely flat out to 5K

 

[Rupunzell]

Consider getting a spare cam housing with a NA specific performance cam and exhaust header and keeping the current set up for the turbo later.

Keep a the valve buckets & shims specific to each cam and housing relative to the same head. This way, cam swaps are easier.

The FIAT 1.5L is a short stroke engine, low RPM torque is not one of it's great strengths.

The plan is to go turbo. I plan on bolting it up directly to the stock exhaust manifold then having an exhaust welded up, and using turbo specific cams.

Though at the moment this might not happen as quickly as I expected, so I am looking into NA cams as well as headers & exhaust.

 

[abec]

I may end up doing just that, I am considering all options right now. I kind of regret not swaping to a more modern power plant when I had the cash to do so, but I want to make the most of the choices I have made. I want to make sure I can get the motor dialed in as is, get any kinks out of the way before I make my next step twards turbo or na.

I am well aware of the difference between long stroke motors such as the VW's and short stroke motors like the fiats.

From what I know, short stroke large bore (over squared) motor like the 1500 should have almost anemic amounts of torque but spin like a top in high rpms (IE. Honda motors). That is why I question why my motor is not making more power, if it has 78 torque It would be normal to see 90+ hp rather then the 74 its making.

The question is, should I tell my tuner to ignore the amount of jumping in the dyno graph near high RPM and just tune it for max power. Its not that they couldn't get more power, I think they assumed something was wrong so they didn't push it to its max.

Consider getting a spare cam housing with a NA specific performance cam and exhaust header and keeping the current set up for the turbo later.

Keep a the valve buckets & shims specific to each cam and housing relative to the same head. This way, cam swaps are easier.

The FIAT 1.5L is a short stroke engine, low RPM torque is not one of it's great strengths.