GT380 Excessive smoke, black oil out exhausts & missfire

CFS · Post by **CFS** » Sat Apr 27, 2019 11:40 am

No 2 stroke oil added to the fuel.
As explained earlier a plug chop is difficult to achieve as I don’t have a road to do this safely where I live therefore I use the motorway for WOT riding and then check the plugs.
The plugs used on both occasions were new.

I have never holed a piston but the bike has been standing since 2003 when the other motor ran a big end so haven’t really ridden on lead free fuel except for the approximate 100km done since it’s been running again.

Can someone advise where I could get some aftermarket pistons (+1.5mm) (OEM too expensive) at a reasonable price (preferably from the UK) and also who could ceramic coat the tops?

I will re-tune to a less advanced timing figure, re-check carbs and jetting and stock plugs with the re-build and see how it turns out.

Carlos

sportston · Post by **sportston** » Sat Apr 27, 2019 4:43 pm

CFS wrote: Can someone advise where I could get some aftermarket pistons (+1.5mm) (OEM too expensive) at a reasonable price (preferably from the UK) and also who could ceramic coat the tops?

Try here for ceramic coating http://www.camcoat.com/
As for cheap pistons... Mitaka might be your best value aftermarket bet. 01.3301.150 are about £45 each piston kit http://www.mitaka.co.uk/ROAD_BIKE_PISTO ... KI/X7P.htm
Also make sure you use high octane fuel. Cheap low octane unleaded may seem appealing but it is a false economy if it ruins your motor.

tz375 · Post by **tz375** » Mon Apr 29, 2019 10:13 pm

Be sure to do a leakdown test when the motor is back together - before you add carbs or exhausts. That's crucial.

I like to set timing with a dial gauge with the heads off, so I can set them all exactly the same. It's easy to do that on the bench with the heads off before you fit it into the frame. That's also the best time to do a leakdown test.

CFS · Post by **CFS** » Wed May 01, 2019 3:05 am

Hi and thanks for the advice.

I have never done a leak down test before but will acquire the necessary equipment to allow me to undertake this test.
From reading previous posts on here can you please confirm if I have understood the process correctly:
a) Pressure 6Psi. Never exceed 10Psi. I presume that I could used a compressor for this or does it need to be a manual pump?
b) Ideally the pressure supply should be through the inlet.
c) Piston to be at TDC.
d) Each cylinder to be tested independantly/individually.

As for the timing I normally set this with the heads on as I have an dial guage adaptor that screws into the plug hole, but could attempt this without the heads.

Can someone please advise what is the best material to seal the crankcase halves. The product I previously used is finished and i need to purchase an alternative. I underdstand that Three Bond and Loctite have products on the market for this - any advice?

Many Thanks
Carlos

jabcb · Post by **jabcb** » Wed May 01, 2019 7:45 am

I use ThreeBond 1184 to seal the crankcase halves.

I’ve never done a leakdown test. But I think its likely you will end up buying another set of crank seals if you use a shop compressor to do the leakdown test.

tz375 · Post by **tz375** » Wed May 01, 2019 7:53 am

6psi is fine. Much more and the seals will be damaged.

Hand pump is best. Typically people use the same hand held pump that comes with blood pressure cuff

https://www.zoro.com/hcs-bulb-and-air-r ... /G2819890/" onclick="window.open(this.href);return false;

Air can go in through the plug or inlet. Those both work and are easy to get to.

On a Suzuki each cylinder can be tested individually

There are many videos on youtube to guide you. Any questions, come back and ask.

https://www.youtube.com/watch?v=zdq7NRcUIp8" onclick="window.open(this.href);return false;

CFS · Post by **CFS** » Fri May 10, 2019 5:26 pm

Just had a look at the damaged piston & bore and will have to re-bore next size up (+1.5).
Base on this I think I will take the opportunity and port the barrels for a mild tune. Can anyone advise on port dimensions that will give a better mid range and a bit on the top end. Don’t want a motor with a short/small powerband.
I also don’t have the equipment to alter the transfer ports so it will be inlet and exhaust only.

Thanks
Carlos

sportston · Post by **sportston** » Sat May 11, 2019 10:25 am

Some info here on one of my old posts.
viewtopic.php?f=5&t=8938

CFS · Post by **CFS** » Thu May 16, 2019 5:52 am

Hi,
Thanks for the link to the post.

What option did you finally take regarding the porting? Did you port and to what dimensions?
I understand that you are still putting yours together and may not have feedback regarding performance, etc due to limited riding time but would appreciate your feedback.

Has anyone on the forum ported a 380 motor and if possible please share what you have done. I have searched this forum and cannot find much regarding porting dimensions. I am not looking to race but would like a little more out of it. I have read Bell’s book and done various calculations but would like some feedback as I don’t want anything too radical.

I may reinstall the skimmed head when complete but would like to do some mild porting. As previously stated I won’t touch the transfers except for a clean as I don’t have the equipment to alter these.

Cheers
Carlos

sportston · Post by **sportston** » Thu May 16, 2019 10:07 am

I did very little porting. Only did mild outer port work and ground the inlet tract fork until it was razor sharp. I didn't alter the port height or width on the piston side as I didn't want to make it too uneconomical to use as a commuter bike. I did put a set of Higgspeeds on it. Also fitted a set of GT550 carbs (with GT550 inlet rubbers), skimmed the head and fitted shorter copper head gaskets, ceramic coated the new piston crowns and teflon coated the skirts (not sure how much difference the teflon coating will make, but it might help reduce friction a smidgen). I got the crankshaft balanced while it was being rebuilt. With heat dissipation in mind, I drilled some tiny holes in the head and barrel above the exhaust ports, to create a small amount of turbulence. Also fitted new air filter elements, electronic ignition, with new coils, copper-core leads and one heat rating cooler NGK plugs.
I figure with all that work I should have a couple of extra horses without turning it into a race engine. I was told that it should be fairly fun to ride without going further. If I find it too boring, I'll whip the barrels off and change port heights and widths and pray that it doesn't make it as thirsty as a Kawasaki triple.

tz375 · Post by **tz375** » Fri May 17, 2019 6:39 pm

GT380 is 54x54 IIRC - same as an RD250.

Look at stock RD250 timing and compare that data with your 380 just to get a ball park of how much might need to be removed. An RD is pretty tame too, but not as bland as the Suzuki triples which are all really softly tuned.
On a a 750 for example the transfers are often lifted 3.5mm with a spacer plate and the exhaust by almost 7mm in total. 380 won't need that much but give you an idea of what you may need to do, but start with and RD or stage 2 X7.

jabcb · Post by **jabcb** » Sat May 18, 2019 6:23 am

Have no expertise in porting so this is more of a question than advice.

Doesn’t the RD250 have reed valves? And wouldn’t those reed valves impact optimal porting specs?
If the answers are yes, than would the RD250 porting be applicable to a non-reed valve GT380?

CFS · Post by **CFS** » Sat May 18, 2019 11:20 am

Hi,

I understand from reading in earlier posts that tz375 uses Mota in his designs.
Below I have added an extract from another forum on a GT380 build where this package was used for the design and was wondering if you could interpret the data and give your comments. The person doing the mods stated that this was good for about 60hp. I don't need anywhere near that amount but it would be interesting to know.

Thanks
Carlos

I remembered what the point of this build was and stopped playing too much, I optimized some pipes and found cutting the piston skirt 10mm seems to bump power and not have much in the way of flat spots, the intake tract is designed around some carbs I had saved for this bike, power shows 60 with a pretty smooth curve, I can live with that, the whole idea of this project was to learn about the process of designing a bike wholly, manufacturing the parts, and then assembling as efficiently as possible, going full radical on the engine isn't in the cards for this one, but it will be cool to keep playing with 2 strokes, I think I could build some stupid stuff with them.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* *
* ENGINE PERFORMANCE FILE *
* *
* FILE NAME: C:\USERS\PUBLIC\MOTA\SAMPLES-6\GT1D.PER *
* *
* DATE (D/M/Y): 27/6/2018 *
* *
* TIME: 10:33 a.m. *
* *
* COMMENT: "Optimisation output file" *
* *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

ENGINE SPECIFICATION
--------------------

BASIC ENGINE CONFIGURATION:
Piston controlled induction.
Single piece expansion chamber.

PIPE STEP FACTOR:
Lower Limit: 4.1 Upper Limit: 16.0 Value: 10.0

SCAVENGING PARAMETERS:

Maximum Short Circuit Ratio: 0.20
Maximum Displacement Scavenging Fraction: 0.80
Scavenge Ratio for Zero Short Circuit: 1.00
Scavenge Ratio for No Displacement Scavenging: 0.50

BORE STROKE CONNECTING ROD GUDGEON PIN
(mm) (mm) LENGTH (mm) OFFSET (mm)

54.00 54.00 110.00 0.00

BORE/STROKE CONNECTING ROD LENGTH
RATIO /STROKE RATIO

1.0000 2.0370

BOX NAME CLEARANCE SWEPT COMPRESSION
VOLUME (cc) VOLUME (cc) RATIO

CRANKCASE 225.00 123.67 1.55
CYLINDER 10.00 123.67 8.49

CALORIFIC VALUE OF AIR FUEL THROTTLE AREA
FUEL (BTU/lb) RATIO RATIO

18536.3 13.00 1.000

COMBUSTION PARAMETERS:

COMBUSTION BURN PERIOD
EFFICIENCY (degrees)

0.800 55.0

IGNITION TIMING:

IGNITION TIMING
(degrees BTDC)
24.5

AMBIENT CONDITIONS:

TEMPERATURE (F) PRESSURE (psi)

68.0 14.70

PISTON PORT DIMENSIONS:

PORT NUMBER BRIDGED MAXIMUM PORT WIDTH HEIGHT CORNER RADII
NAME OF PORTS (Y/N) ANGULAR ARC CHORD (mm) TOP BOTTOM
(deg) (mm) (mm) (mm) (mm)

INLET 2 Y 38.20 18.00 17.67 19.17 3.00 3.00
TRANSFER 2 N 65.78 31.00 29.33 10.99 3.00 6.00
EXHAUST 1 - 78.52 37.00 34.17 21.31 5.00 5.00

PORT BRIDGE RADII AT BRIDGE
NAME WIDTH TOP BOTTOM
(mm) (mm) (mm)

INLET 5.00 3.00 3.00

PORT TOTAL ATTITUDE ANGLES
NAME AREA AXIAL RADIAL
(sq.cm) (deg) (deg)

INLET 6.6213 5.0 0.0
TRANSFER 6.0571 0.0 20.0
EXHAUST 7.0667 15.0 0.0

PISTON PORT TIMINGS:

PORT NAME START OPEN FULL OPEN START OPEN FULL OPEN
(deg ATDC) (deg ATDC) (mm from TDC) (mm from TDC)

INLET 270.0 311.0 30.37 11.19
TRANSFER 120.0 180.0 43.01 54.00
EXHAUST 95.0 180.0 32.69 54.00

INLET DUCT

A bellmouth is present at the inlet of section 1.
Section 4 is the inlet duct portion inside the barrel.

SECTION LENGTH DIAMETER IN DIAMETER OUT AREA IN AREA OUT
(mm) ( mm) (mm) (sq.cm) (sq.cm)

1 75.0 60.0 35.0 28.27 9.62
2 95.0 35.0 29.0 9.62 6.61
3 25.0 29.0 29.0 6.61 6.61
4 56.0 29.0 29.0 6.61 6.60

TRANSFER DUCTS

Smooth entry to each transfer duct 2 is NOT assumed.
Diameters and areas are those of each individual duct in a group.

TRANSFER (2 separate ducts)

SECTION LENGTH DIAMETER IN DIAMETER OUT AREA IN AREA OUT
(mm) (mm) (mm) (sq.cm) (sq.cm)

1 50.0 24.0 19.0 4.52 2.85

EXHAUST DUCT (single air cooled system)

SECTION LENGTH DIAMETER AREA CONE VOLUME
(mm) IN OUT IN OUT ANGLE (cc)
(mm) (mm) (sq.cm) (sq.cm) (deg)

BARREL 60.0 29.5 33.2 6.83 8.66
1 157.8 33.2 39.3 8.66 12.13 2.2 163.2
2 171.5 39.3 87.2 12.13 59.72 15.9 564.6
3 240.4 87.2 122.2 59.72 117.28 8.3 2089.0
4 39.2 122.2 110.8 117.28 96.42 16.5 418.2
5 63.2 110.8 79.5 96.42 49.64 27.8 453.4
6 51.5 79.5 33.5 49.64 8.81 48.1 136.3
TAIL 86.7 32.5 32.5 8.30 8.30

ENGINE PERFORMANCE INDICATORS
-----------------------------

SPEED POWER TORQUE POWER TORQUE
(rpm) (kW) (Nm) (hp) (ft lbf)

1000 0.370 3.535 0.496 2.607
2000 0.599 2.860 0.803 2.109
3000 1.051 3.344 1.409 2.467
4000 2.197 5.244 2.946 3.868
5000 5.033 9.612 6.749 7.090
6000 7.270 11.570 9.749 8.534
7000 9.548 13.026 12.805 9.607
8000 13.193 15.748 17.692 11.615
9000 15.052 15.970 20.184 11.779
10000 11.601 11.078 15.557 8.171

SPEED IGNITION TIMING AIR FUEL
(rpm) (degrees BTDC) RATIO

1000 24.5 13.00
2000 24.5 13.00
3000 24.5 13.00
4000 24.5 13.00
5000 24.5 13.00
6000 24.5 13.00
7000 24.5 13.00
8000 24.5 13.00
9000 24.5 13.00
10000 24.5 13.00

SPEED MEAN EFFECTIVE PRESSURES (atm)
(rpm) BMEP PMEP FMEP IMEP

1000 1.772 0.082 0.029 1.884
2000 1.434 0.092 0.059 1.585
3000 1.677 0.100 0.088 1.865
4000 2.629 0.233 0.117 2.979
5000 4.820 0.408 0.147 5.374
6000 5.801 0.501 0.176 6.478
7000 6.531 0.539 0.205 7.275
8000 7.896 0.579 0.234 8.710
9000 8.008 0.549 0.264 8.820
10000 5.554 0.418 0.293 6.266

SPEED FUEL CONSUMPTION FLOW RATIOS SCAVENGE RATIOS
(rpm) (BSFC: lb/hph) DELIVERY EXHAUST MASS VOLUME

1000 1.032 0.337934 0.337727 0.337 0.340
2000 1.032 0.273492 0.273015 0.273 0.274
3000 0.943 0.292168 0.294875 0.300 0.301
4000 0.899 0.436934 0.442361 0.443 0.444
5000 0.941 0.838447 0.838550 0.839 0.867
6000 0.872 0.935362 0.935491 0.935 0.982
7000 0.929 1.121026 1.120974 1.121 1.200
8000 0.831 1.213048 1.213049 1.213 1.308
9000 0.774 1.145004 1.145011 1.145 1.257
10000 0.913 0.936711 0.936364 0.937 0.941

SPEED EFFICIENCIES PERCENTAGE ENERGY LOSS
(rpm) SCAVENGE TRAPPING CHARGING IN EXHAUST SYSTEM

1000 0.488 0.668 0.226 32.98
2000 0.424 0.684 0.187 53.57
3000 0.477 0.712 0.213 41.77
4000 0.574 0.671 0.297 26.86
5000 0.774 0.577 0.483 11.45
6000 0.840 0.591 0.553 9.84
7000 0.875 0.532 0.597 8.10
8000 0.879 0.585 0.710 7.02
9000 0.864 0.636 0.728 7.46
10000 0.834 0.548 0.513 7.17

PEAK CYLINDER TEMPERATURE LIMITS AT CENTRE
SPEED PRESSURE TEMPERATURE OF THE EXPANSION CHAMBER (F)
(rpm) (atm) (F) MEAN LOW HIGH

1000 27.85 2276.12 449.4 446.9 456.7
2000 25.45 2150.92 446.0 441.7 455.2
3000 27.04 2296.55 494.1 484.4 509.9
4000 36.22 2792.18 552.4 536.4 577.5
5000 48.61 3263.44 613.9 589.7 654.1
6000 55.03 3588.20 671.9 644.6 730.1
7000 58.13 3719.44 648.4 611.5 719.2
8000 69.42 3783.74 711.5 663.9 780.1
9000 71.32 3737.32 741.3 686.8 816.5
10000 48.03 3449.45 633.3 597.4 686.3

The Specific Time Area of a port is the sum of all port areas
over time divided by the cylinder swept volume.
The units sec/metre and sec.sq mm/cc are equivalent.

SPECIFIC PORT TIME AREA
(sec/metre x 10000)
SPEED INLET TRANSFER EXHAUST
(rpm)

1000 1245.2 623.9 1031.8
2000 622.6 311.9 515.9
3000 415.1 208.0 343.9
4000 311.3 156.0 258.0
5000 249.0 124.8 206.4
6000 207.5 104.0 172.0
7000 177.9 89.1 147.4
8000 155.7 78.0 129.0
9000 138.4 69.3 114.6
10000 124.5 62.4 103.2

Elapsed time: 24.00 seconds

CFS · Post by **CFS** » Sat May 18, 2019 11:20 am

Hi,

I understand from reading in earlier posts that tz375 uses Mota in his designs.
Below I have added an extract from another forum on a GT380 build where this package was used for the design and was wondering if you could interpret the data and give your comments. The person doing the mods stated that this was good for about 60hp. I don't need anywhere near that amount but it would be interesting to know.

Thanks
Carlos

I remembered what the point of this build was and stopped playing too much, I optimized some pipes and found cutting the piston skirt 10mm seems to bump power and not have much in the way of flat spots, the intake tract is designed around some carbs I had saved for this bike, power shows 60 with a pretty smooth curve, I can live with that, the whole idea of this project was to learn about the process of designing a bike wholly, manufacturing the parts, and then assembling as efficiently as possible, going full radical on the engine isn't in the cards for this one, but it will be cool to keep playing with 2 strokes, I think I could build some stupid stuff with them.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* *
* ENGINE PERFORMANCE FILE *
* *
* FILE NAME: C:\USERS\PUBLIC\MOTA\SAMPLES-6\GT1D.PER *
* *
* DATE (D/M/Y): 27/6/2018 *
* *
* TIME: 10:33 a.m. *
* *
* COMMENT: "Optimisation output file" *
* *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

ENGINE SPECIFICATION
--------------------

BASIC ENGINE CONFIGURATION:
Piston controlled induction.
Single piece expansion chamber.

PIPE STEP FACTOR:
Lower Limit: 4.1 Upper Limit: 16.0 Value: 10.0

SCAVENGING PARAMETERS:

Maximum Short Circuit Ratio: 0.20
Maximum Displacement Scavenging Fraction: 0.80
Scavenge Ratio for Zero Short Circuit: 1.00
Scavenge Ratio for No Displacement Scavenging: 0.50

BORE STROKE CONNECTING ROD GUDGEON PIN
(mm) (mm) LENGTH (mm) OFFSET (mm)

54.00 54.00 110.00 0.00

BORE/STROKE CONNECTING ROD LENGTH
RATIO /STROKE RATIO

1.0000 2.0370

BOX NAME CLEARANCE SWEPT COMPRESSION
VOLUME (cc) VOLUME (cc) RATIO

CRANKCASE 225.00 123.67 1.55
CYLINDER 10.00 123.67 8.49

CALORIFIC VALUE OF AIR FUEL THROTTLE AREA
FUEL (BTU/lb) RATIO RATIO

18536.3 13.00 1.000

COMBUSTION PARAMETERS:

COMBUSTION BURN PERIOD
EFFICIENCY (degrees)

0.800 55.0

IGNITION TIMING:

IGNITION TIMING
(degrees BTDC)
24.5

AMBIENT CONDITIONS:

TEMPERATURE (F) PRESSURE (psi)

68.0 14.70

PISTON PORT DIMENSIONS:

PORT NUMBER BRIDGED MAXIMUM PORT WIDTH HEIGHT CORNER RADII
NAME OF PORTS (Y/N) ANGULAR ARC CHORD (mm) TOP BOTTOM
(deg) (mm) (mm) (mm) (mm)

INLET 2 Y 38.20 18.00 17.67 19.17 3.00 3.00
TRANSFER 2 N 65.78 31.00 29.33 10.99 3.00 6.00
EXHAUST 1 - 78.52 37.00 34.17 21.31 5.00 5.00

PORT BRIDGE RADII AT BRIDGE
NAME WIDTH TOP BOTTOM
(mm) (mm) (mm)

INLET 5.00 3.00 3.00

PORT TOTAL ATTITUDE ANGLES
NAME AREA AXIAL RADIAL
(sq.cm) (deg) (deg)

INLET 6.6213 5.0 0.0
TRANSFER 6.0571 0.0 20.0
EXHAUST 7.0667 15.0 0.0

PISTON PORT TIMINGS:

PORT NAME START OPEN FULL OPEN START OPEN FULL OPEN
(deg ATDC) (deg ATDC) (mm from TDC) (mm from TDC)

INLET 270.0 311.0 30.37 11.19
TRANSFER 120.0 180.0 43.01 54.00
EXHAUST 95.0 180.0 32.69 54.00

INLET DUCT

A bellmouth is present at the inlet of section 1.
Section 4 is the inlet duct portion inside the barrel.

SECTION LENGTH DIAMETER IN DIAMETER OUT AREA IN AREA OUT
(mm) ( mm) (mm) (sq.cm) (sq.cm)

1 75.0 60.0 35.0 28.27 9.62
2 95.0 35.0 29.0 9.62 6.61
3 25.0 29.0 29.0 6.61 6.61
4 56.0 29.0 29.0 6.61 6.60

TRANSFER DUCTS

Smooth entry to each transfer duct 2 is NOT assumed.
Diameters and areas are those of each individual duct in a group.

TRANSFER (2 separate ducts)

SECTION LENGTH DIAMETER IN DIAMETER OUT AREA IN AREA OUT
(mm) (mm) (mm) (sq.cm) (sq.cm)

1 50.0 24.0 19.0 4.52 2.85

EXHAUST DUCT (single air cooled system)

SECTION LENGTH DIAMETER AREA CONE VOLUME
(mm) IN OUT IN OUT ANGLE (cc)
(mm) (mm) (sq.cm) (sq.cm) (deg)

BARREL 60.0 29.5 33.2 6.83 8.66
1 157.8 33.2 39.3 8.66 12.13 2.2 163.2
2 171.5 39.3 87.2 12.13 59.72 15.9 564.6
3 240.4 87.2 122.2 59.72 117.28 8.3 2089.0
4 39.2 122.2 110.8 117.28 96.42 16.5 418.2
5 63.2 110.8 79.5 96.42 49.64 27.8 453.4
6 51.5 79.5 33.5 49.64 8.81 48.1 136.3
TAIL 86.7 32.5 32.5 8.30 8.30

ENGINE PERFORMANCE INDICATORS
-----------------------------

SPEED POWER TORQUE POWER TORQUE
(rpm) (kW) (Nm) (hp) (ft lbf)

1000 0.370 3.535 0.496 2.607
2000 0.599 2.860 0.803 2.109
3000 1.051 3.344 1.409 2.467
4000 2.197 5.244 2.946 3.868
5000 5.033 9.612 6.749 7.090
6000 7.270 11.570 9.749 8.534
7000 9.548 13.026 12.805 9.607
8000 13.193 15.748 17.692 11.615
9000 15.052 15.970 20.184 11.779
10000 11.601 11.078 15.557 8.171

SPEED IGNITION TIMING AIR FUEL
(rpm) (degrees BTDC) RATIO

1000 24.5 13.00
2000 24.5 13.00
3000 24.5 13.00
4000 24.5 13.00
5000 24.5 13.00
6000 24.5 13.00
7000 24.5 13.00
8000 24.5 13.00
9000 24.5 13.00
10000 24.5 13.00

SPEED MEAN EFFECTIVE PRESSURES (atm)
(rpm) BMEP PMEP FMEP IMEP

1000 1.772 0.082 0.029 1.884
2000 1.434 0.092 0.059 1.585
3000 1.677 0.100 0.088 1.865
4000 2.629 0.233 0.117 2.979
5000 4.820 0.408 0.147 5.374
6000 5.801 0.501 0.176 6.478
7000 6.531 0.539 0.205 7.275
8000 7.896 0.579 0.234 8.710
9000 8.008 0.549 0.264 8.820
10000 5.554 0.418 0.293 6.266

SPEED FUEL CONSUMPTION FLOW RATIOS SCAVENGE RATIOS
(rpm) (BSFC: lb/hph) DELIVERY EXHAUST MASS VOLUME

1000 1.032 0.337934 0.337727 0.337 0.340
2000 1.032 0.273492 0.273015 0.273 0.274
3000 0.943 0.292168 0.294875 0.300 0.301
4000 0.899 0.436934 0.442361 0.443 0.444
5000 0.941 0.838447 0.838550 0.839 0.867
6000 0.872 0.935362 0.935491 0.935 0.982
7000 0.929 1.121026 1.120974 1.121 1.200
8000 0.831 1.213048 1.213049 1.213 1.308
9000 0.774 1.145004 1.145011 1.145 1.257
10000 0.913 0.936711 0.936364 0.937 0.941

SPEED EFFICIENCIES PERCENTAGE ENERGY LOSS
(rpm) SCAVENGE TRAPPING CHARGING IN EXHAUST SYSTEM

1000 0.488 0.668 0.226 32.98
2000 0.424 0.684 0.187 53.57
3000 0.477 0.712 0.213 41.77
4000 0.574 0.671 0.297 26.86
5000 0.774 0.577 0.483 11.45
6000 0.840 0.591 0.553 9.84
7000 0.875 0.532 0.597 8.10
8000 0.879 0.585 0.710 7.02
9000 0.864 0.636 0.728 7.46
10000 0.834 0.548 0.513 7.17

PEAK CYLINDER TEMPERATURE LIMITS AT CENTRE
SPEED PRESSURE TEMPERATURE OF THE EXPANSION CHAMBER (F)
(rpm) (atm) (F) MEAN LOW HIGH

1000 27.85 2276.12 449.4 446.9 456.7
2000 25.45 2150.92 446.0 441.7 455.2
3000 27.04 2296.55 494.1 484.4 509.9
4000 36.22 2792.18 552.4 536.4 577.5
5000 48.61 3263.44 613.9 589.7 654.1
6000 55.03 3588.20 671.9 644.6 730.1
7000 58.13 3719.44 648.4 611.5 719.2
8000 69.42 3783.74 711.5 663.9 780.1
9000 71.32 3737.32 741.3 686.8 816.5
10000 48.03 3449.45 633.3 597.4 686.3

The Specific Time Area of a port is the sum of all port areas
over time divided by the cylinder swept volume.
The units sec/metre and sec.sq mm/cc are equivalent.

SPECIFIC PORT TIME AREA
(sec/metre x 10000)
SPEED INLET TRANSFER EXHAUST
(rpm)

1000 1245.2 623.9 1031.8
2000 622.6 311.9 515.9
3000 415.1 208.0 343.9
4000 311.3 156.0 258.0
5000 249.0 124.8 206.4
6000 207.5 104.0 172.0
7000 177.9 89.1 147.4
8000 155.7 78.0 129.0
9000 138.4 69.3 114.6
10000 124.5 62.4 103.2

Elapsed time: 24.00 seconds

sportston · Post by **sportston** » Sat May 18, 2019 12:48 pm

That is a very interesting set of figures. Does anyone have a rocket scientist in their back pocket to decode them?

GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire

Re: GT380 Excessive smoke, black oil out exhausts & missfire