Restricter Race Motors -make more power than your opposition

[Pinhead]

Eliminate the part about fuel atomization, vaporization and volatility (lack there-of) and you've got the means to build a fuel economy motor. Part-Throttle Cruise=Intake Restrictor.

[MAP]

Greetings Stan,

Would you please check the software code - the graphs show a reversal of piston velocity near BDC for rods shorter than 7.00". This ought only to occur when the rod length is less than the stroke/2 (a physical impossibility, btw.)

Best,
Mark

[MAP]

Greetings,

I noodled around with some trigonometry and got the following, FYI:

1.) Piston displacement down bore =

l +(s/2)*(1-cos(theta))-(L^2-(s^2/4)*sin^2(theta))^1/2

2.) Magnitude of second derivative of displacement with repect to theta, which at any given engine speed, is directly proportional to magnitude of piston acceleration:

Case a.) theta = 0 (TDC)

=(s^2+2*s*L)/(4*L)

Case b.) theta = 2pi (BDC)

=(s^2-2*s*L)/(4*L)
Forming a ratio of these two accelerations is especially interesting:

Accel TDC/Accel BDC = |(s^2+2*s*l)/(s^2-2*s*l)|

Where:
s = stroke
theta = crankshaft angular position
L = rod length

Example: for S =3.75" and L = 5.7375", get:

Accel TDC/Accel BDC = 1.97

As L approaches infinity, the above ratio approaches one, of course, and the displacement approaches a pure sinusoid.

Greetings Stan: confirmed - the graphs are definitely wrong - please check.

Thanks,
Mark

[DavidVizard-GFN]

Originally Posted by 80' 427

We are making 269.9 rwhp (approx 375hp) with a poorly cammed 6" rod 383.

My intake restricted dirt car motor makes right around 370 on our DTS engine dyno and about 330 at the wheels on a Dynojet chassis dyno. (I say 'about' because I did not have time to dig around all the power curves to find the exact numbers but these are close enough). I am using 1 5/8th headers.

Fuel idea is good - it would be interesting to dyno both. The alcohol content is slower to evaporate than typical gasoline front ends. You might want to try blowing down some 93 octane and then add 15% ethanol so that you have in effect brewed your own E15.
DV

[80' 427]

Originally Posted by DavidVizard-GFN

My intake restricted dirt car motor makes right around 370 on our DTS engine dyno and about 330 at the wheels on a Dynojet chassis dyno. (I say 'about' because I did not have time to dig around all the power curves to find the exact numbers but these are close enough). I am using 1 5/8th headers.

Fuel idea is good - it would be interesting to dyno both. The alcohol content is slower to evaporate than typical gasoline front ends. You might want to try blowing down some 93 octane and then add 15% ethanol so that you have in effect brewed your own E85.
DV

We use a mustang dyno and the power numbers are typically lower than a dyno jet. 72% is what they use for a converstion factor. For now we will be stuck with the large headers but may try them later in the year. E85 is cheating in our class. We tryed 3 fuels right from the pump (except 110 sunoco) The power was almost identical (+/-2 hp) and with the cost of fuel going up e10 makes the most economical sence. The other fact is with a limited engine the true compression is lower because of the lack of cylinder filling so we can get away with lower octane fuel. The new engine is a 377 and has 6.125 rods with honda journals(used nascar rods), the stock forged crank was turned down to 1.88 on the journals. The bob weight is 1581 grams. I wonder what advantages the light weight and reduced journal size will have on horsepower. The heads are some used sprintcar early bowties with titanium valves and I am hoping the by reducing spring pressure we can gain back some more fiction losses. The biggest limitation are the stock cast intake and rochester 2gc (approx 480cfm @ 3.0hg) So not only is there a large restiction the intake also limits air flow. Finally we are only allowed 9 to 1 which is which is just one more bite out of our horsepower cookie. I still wonder what horse power gains could be made with a cam ground spec to crutch the intake. Right now we typically run a 1.6 on the intake and 1.5 on the exhaust and it shows a bump of 5lbs of torque across our very flat curve.

Thanks again for writting the article it has helped alot.

John Ebke

[Billzilla]

Originally Posted by DavidVizard-GFN

Internal Friction and Component Geometry

An engine can loose a considerable amount of power to internal losses both pumping and friction.

Loose or lose?

[Billzilla]

Originally Posted by DavidVizard-GFN

Internal Friction and Component Geometry

An engine can loose a considerable amount of power to internal losses both pumping and friction.

Loose or lose?

[Stan Weiss]

Originally Posted by MAP

Greetings Stan,

Would you please check the software code - the graphs show a reversal of piston velocity near BDC for rods shorter than 7.00". This ought only to occur when the rod length is less than the stroke/2 (a physical impossibility, btw.)

Best,
Mark

Mark,
That graph was only acceleration. This one has both acceleration and velocity.
Stan

[80' 427]

I guess I can't read I thought you wrote E85. We tried some 50/50 92 E85 and the power didn't increase but this summer the intake cooling from the ethonal could make a big difference.

[Stan Weiss]

Piston Piston

Bore = 4.0   Stroke = 3.75   Rod Length = 5.7375   RPM = 6500
Wrist Pin Offset = 0.0
Rotation Time of crank per degree in Milliseconds    0.0256410
Rotation Time of crank per rev in Milliseconds       9.2307692
Crankshaft rev's per Second                          108.3333333
Crankshaft Degrees at which Rod and Crank are 90 Degrees 71.9027

Crank      Piston     Crank       Rod    Cylinder   Cylinder
Angle      Travel      Rod       Bore     Volume     Volume
Degree     Inches     Angle      Angle      CI         cc
-ATDC 
   .0000   .000000  180.00000   0.00000   0.00000    0.00000
  2.5000   .002368  176.68324   0.81676   0.02975    0.48754
  5.0000   .009463  173.36787   1.63213   0.11891    1.94861
  7.5000   .021263  170.05527   2.44473   0.26720    4.37859
 10.0000   .037731  166.74684   3.25316   0.47414    7.76983
 12.5000   .058815  163.44397   4.05603   0.73910   12.11160
 15.0000   .084449  160.14805   4.85195   1.06122   17.39023
 17.5000   .114551  156.86045   5.63955   1.43949   23.58909
 20.0000   .149028  153.58257   6.41743   1.87274   30.68868
 22.5000   .187770  150.31578   7.18422   2.35959   38.66669
 25.0000   .230656  147.06147   7.93853   2.89851   47.49813
 27.5000   .277553  143.82102   8.67898   3.48783   57.15537
 30.0000   .328314  140.59578   9.40422   4.12571   67.60830
 32.5000   .382780  137.38712  10.11288   4.81016   78.82442
 35.0000   .440785  134.19639  10.80361   5.53906   90.76898
 37.5000   .502147  131.02492  11.47508   6.31017  103.40517
 40.0000   .566681  127.87405  12.12595   7.12112  116.69421
 42.5000   .634187  124.74508  12.75492   7.96943  130.59556
 45.0000   .704463  121.63930  13.36070   8.85254  145.06709
 47.5000   .777295  118.55796  13.94204   9.76778  160.06529
 50.0000   .852469  115.50229  14.49771  10.71244  175.54541
 52.5000   .929760  112.47350  15.02650  11.68371  191.46175
 55.0000  1.008944  109.47274  15.52726  12.67877  207.76782
 57.5000  1.089793  106.50115  15.99885  13.69474  224.41655
 60.0000  1.172075  103.55978  16.44022  14.72872  241.36055
 62.5000  1.255560  100.64966  16.85034  15.77783  258.55233
 65.0000  1.340018   97.77175  17.22825  16.83917  275.94451
 67.5000  1.425222   94.92696  17.57304  17.90986  293.49005
 70.0000  1.510944   92.11611  17.88389  18.98708  311.14249
 72.5000  1.596963   89.33997  18.16003  20.06803  328.85614
 75.0000  1.683063   86.59922  18.40078  21.14999  346.58629
 77.5000  1.769032   83.89446  18.60554  22.23031  364.28944
 80.0000  1.854664   81.22621  18.77379  23.30640  381.92344
 82.5000  1.939764   78.59490  18.90510  24.37579  399.44769
 85.0000  2.024142   76.00087  18.99913  25.43612  416.82327
 87.5000  2.107618   73.44435  19.05565  26.48510  434.01310
 90.0000  2.190021   70.92550  19.07450  27.52061  450.98204
 92.5000  2.271190   68.44435  19.05565  28.54062  467.69696
 95.0000  2.350976   66.00087  18.99913  29.54323  484.12687
 97.5000  2.429237   63.59490  18.90510  30.52670  500.24291
100.0000  2.505845   61.22621  18.77379  31.48938  516.01842
102.5000  2.580680   58.89446  18.60554  32.42978  531.42892
105.0000  2.653634   56.59922  18.40078  33.34655  546.45210
107.5000  2.724610   54.33997  18.16003  34.23846  561.06783
110.0000  2.793519   52.11611  17.88389  35.10440  575.25804
112.5000  2.860284   49.92696  17.57304  35.94339  589.00670
115.0000  2.924837   47.77175  17.22825  36.75458  602.29971
117.5000  2.987117   45.64966  16.85034  37.53722  615.12486
120.0000  3.047075   43.55978  16.44022  38.29067  627.47165
122.5000  3.104666   41.50115  15.99885  39.01439  639.33123
125.0000  3.159856   39.47274  15.52726  39.70792  650.69627
127.5000  3.212616   37.47350  15.02650  40.37092  661.56084
130.0000  3.262922   35.50229  14.49771  41.00309  671.92027
132.5000  3.310759   33.55796  13.94204  41.60422  681.77104
135.0000  3.356113   31.63930  13.36070  42.17416  691.11065
137.5000  3.398977   29.74508  12.75492  42.71281  699.93749
140.0000  3.439347   27.87405  12.12595  43.22011  708.25074
142.5000  3.477222   26.02492  11.47508  43.69607  716.05023
145.0000  3.512605   24.19639  10.80361  44.14069  723.33638
147.5000  3.545498   22.38712  10.11288  44.55405  730.11001
150.0000  3.575909   20.59578   9.40422  44.93620  736.37234
152.5000  3.603844   18.82102   8.67898  45.28724  742.12483
155.0000  3.629311   17.06147   7.93853  45.60726  747.36912
157.5000  3.652318   15.31578   7.18422  45.89638  752.10698
160.0000  3.672875   13.58257   6.41743  46.15471  756.34018
162.5000  3.690990   11.86045   5.63955  46.38235  760.07049
165.0000  3.706671   10.14805   4.85195  46.57940  763.29960
167.5000  3.719925    8.44397   4.05603  46.74596  766.02905
170.0000  3.730760    6.74684   3.25316  46.88212  768.26024
172.5000  3.739181    5.05527   2.44473  46.98794  769.99433
175.0000  3.745193    3.36787   1.63213  47.06348  771.23227
177.5000  3.748798    1.68324   0.81676  47.10879  771.97475
180.0000  3.750000    0.00000   0.00000  47.12389  772.22220