Problem med B23 grenrör?

[Panu]

Hi all,

First sorry about english. You can all answer on swedish because I understand it but cannot write it so smoothly. So lets go with english first.

B23 engine witt 531 head. Problem is that powercurve starts falling at 6000 rpm. 195 hp is enough for me but there should be more power between 6000-7000rpm.

During dyno sessions we thought that problem could cause from exhaust manifold?

Engine data:
std B23e bottom, block is grinded little bit. Compression ratio 12.2:1
ported 531 with 46/37 valves (sorry not measured cfm:s)
camshaft is grinded from original camshaft, lift 12,7mm (Degrees 320/104 if I remember correctly) by Laaksonen
48 webers, 42mm venturis
original ignition system, max advance 32-34 deg
4-2-1 grenrör, copy from martelius XL. Primaries 44,5mm/370mm, secondaries 50,8mm. Total length 800mm. 2,5" collector and exhaust. 2 mufflers.
http://www.raak-racing.com/shop/index.p ... t&Itemid=1

I think i should make smaller/longer exhaust manifold? Maybe 4-2-1 with extra long primaries or should I just extend secondaries of current manifold. Like this: http://forum.savarturbo.se/viewtopic.ph ... &start=120

[Erland Cox]

The biggest problem I see is the intake valve lift, it is not enough for more hp.



141.398 Cubic Inches @ 6000 RPM with 114.00 % Volumetric Efficiency PerCent

Required Intake Flow CFM @28 in. = 183.9 to 194.7 at .506 inch Valve Lift
Required Exhaust Flow CFM @28 in. = 142.0 to 153.8 at .478 inch Valve Lift

600 RPM/Sec Dyno Test Lowest Low Average Best
Peak HorsePower 190.4 194.3 196.8 199.3
Peak Torque Lbs-Ft 183.8 188.6 190.6 193.4

HorsePower per CID 1.346 1.374 1.392 1.410
Torque per Cubic Inch 1.300 1.334 1.351 1.368
BMEP in psi 196.0 201.1 203.7 206.3
Carb CFM at 1.5 in Hg. 280 311 327 343

Recommended Intake Valve Lift to prevent Choke = .506 Lift @ 6000 RPM
Recommended Exhaust Valve Lift to prevent Choke = .478 Lift @ 6000 RPM
Recommended Minimum Normal Maximum Time-Area-Duration Lifts
Intake Valve Lift = 0.4489 0.5057 0.5562 0.5005 0.5276 0.5546
Exhaust Valve Lift = 0.4395 0.4777 0.5255 0.4720 0.5016 0.5311
IntOpen= 33.50 IntClose= 61.50 ExhOpen= 65.50 ExhClose= 29.50
Intake Duration @ .050 = 275.00 Exhaust Duration @ .050 = 275.00
Intake CenterLine = 104.00 Exhaust CenterLine = 108.00
Compression Duration= 118.50 Power Duration = 114.50
OverLap Duration = 63.00 Lobe Separation Angle (LSA)= 106.00
Camshaft Advanced = 2.00 degrees Cylinder Ignition Interval= 180 deg.

-- Operating RPM Ranges of various Components --
Best estimate RPM operating range from all Components = 4174 to 6174
Intake Flow CFM @28inches RPM Range from Flow CFM only = 4137 to 6137
Intake and Exhaust Systems operating RPM Range = 4474 to 6474
Intake and Exhaust Time-Area operating RPM Range = 4175 to 6175
Camshaft's Intake and Exhaust Lobes operating RPM range = 4944 to 6944
Intake Valve Curtain Time-Area at 0.500 Lift RPM Range = 3933 to 5933
Exhaust Valve Curtain Time-Area at 0.500 Lift RPM Range = 4280 to 6280

Intake Valve Close RPM = 7012 Exhaust Valve Open RPM = 6739
Intake System RPM = 6444 Exhaust System RPM = 6504
Intake Time-Area RPM = 5994 Exhaust Time-Area RPM = 6356
Intake Mach Z-Factor = 0.490866 Exhaust Mach Z-Factor = 0.609792
Intake Z-Factor Lift = 0.511318 Exhaust Z-Factor Lift = 0.461964

Curtain Area -to- Valve Area Convergence Intake Valve Lift inch= .453
Curtain Area -to- Valve Area Convergence Exhaust Valve Lift inch= .364

Target EGT= 1228.9 degrees F at end of 4 second 600 RPM/Sec Dyno accel. test
Octane (R+M)/2 Method = 108.3 to 107.7 Octane required range
Air Standard Efficiency = 63.78088 % for 12.200:1 Compression Ratio

------- Piston Motion Data -------
Average Piston Speed (FPM)= 3150.00 in Feet Per Minute
Maximum Piston Speed (FPM)= 5134.359 occurs at 75.54332 Degrees ATDC
Piston Depth at 75.543 degree ATDC= 1.3896 inches Cylinder Volume= 255.5 CC
Maximum TDC Rod Tension GForce= 2055.4716 G's
Maximum BDC Rod Compression GForce= 1165.4736 G's

----- Engine Design Specifications -----
( English Units ) ( per each Valve Sq.Inch area )
Engine Size CID = 141.398 Intake Valve Net Area = 2.496
CID per Cylinder = 35.350 Intake Valve Dia. Area = 2.573
Rod/Stroke Ratio = 1.810 Intake Valve Stem Area = 0.077
Bore/Stroke Ratio = 1.200 Exhaust Valve Net Area = 1.591
Int Valve/Bore Ratio = 0.479 Exhaust Valve Dia. Area = 1.667
Exh Valve/Bore Ratio = 0.385 Exhaust Valve Stem Area = 0.077
Exh/Int Valve Ratio = 0.805 Exh/Int Valve Area Ratio = 0.648
Intake Valve L/D Ratio= .276 Exhaust Valve L/D Ratio= .343
CFM/Sq.Inch = 71.5 to 75.7 CFM/Sq.Inch =84.5 to 88.8

Intake Valve Margin CC's Exhaust Valve Margin CC's
1.00 CC = 0.0237 1.00 CC = 0.0366
0.50 CC = 0.0119 0.50 CC = 0.0183
0.25 CC = 0.0059 0.25 CC = 0.0092
0.10 CC = 0.0024 0.10 CC = 0.0037

- Induction System Tuned Lengths - ( Cylinder Head Port + Manifold Runner )
1st Harmonic= 40.631 (usually this Length is never used)
2nd Harmonic= 23.061 (some Sprint Engines and Factory OEM's w/Injectors)
3rd Harmonic= 16.100 (ProStock or Comp SheetMetal Intake • best overall HP )
4th Harmonic= 12.672 (Single-plane Intakes , less Peak Torque • good HP )
5th Harmonic= 10.281 (Torque is reduced, even though Tuned Length)
6th Harmonic= 8.650 (Torque is reduced, even though Tuned Length)
7th Harmonic= 7.465 (Torque is greatly reduced, even though Tuned Length)
8th Harmonic= 6.566 (Torque is greatly reduced, even though Tuned Length)
Note> 2nd and 3rd Harmonics typically create the most Peak Torque
4th Harmonic is used to package Induction System underneath Hood

Plenum Runner Minimum Recommended Entry Area = 1.962 to 2.207 Sq.Inch
Plenum Runner Average Recommended Entry Area = 2.255 Sq.Inch
Plenum Runner Maximum Recommended Entry Area = 2.304 to 2.726 Sq.Inch

Minimum Plenum Volume CC = 324.4 ( typically for Single-Plane Intakes )
Minimum Plenum Volume CID= 19.8 ( typically for Single-Plane Intakes )
Maximum Plenum Volume CC = 2317.1 ( typically for Tunnel Ram Intakes )
Maximum Plenum Volume CID= 141.4 ( typically for Tunnel Ram Intakes )

--- Cross-Sectional Areas at various Intake Port Velocities (@ 28 in.) ---
155 FPS at Intake Valve Curtain Area= 2.843 sq.in. at .500 Lift
172 FPS at Intake Valve OD Area and at Convergence Lift = .453
212 FPS 90% PerCent Rule Seat-Throat Velocity CSA= 2.084 sq.in.
--- 6000 RPM Intake Cross-sectional areas in Square Inches ---
350 FPS CSA= 1.260 Port has Sonic-Choke with HP Loss ( too fast FPS )
330 FPS CSA= 1.337 Port may have Sonic-Choke with HP Loss ( too fast FPS )
311 FPS CSA= 1.419 Highest useable Port velocity ( possible HP loss )
300 FPS CSA= 1.471 Smallest Port CSA ( Hi Velocity FPS • good TQ and HP )
285 FPS CSA= 1.549 Smallest Port CSA ( very good TQ and HP combination )
260 FPS CSA= 1.697 Recommended average Intake Port CSA (very good TQ and HP)
250 FPS CSA= 1.765 Largest recommended average Intake Port CSA ( good HP )
240 FPS CSA= 1.839 Largest recommended average Intake Port CSA (less Peak TQ)
235 FPS CSA= 1.878 Largest recommended Intake Port Gasket Entry area CSA
225 FPS CSA= 1.962 Largest Intake Port Gasket Entry CSA ( Slow FPS )
215 FPS CSA= 2.053 Possible Torque Loss with Reversion ( Slow FPS )
210 FPS CSA= 2.102 Torque Loss + Reversion possibility ( too slow FPS )
200 FPS CSA= 2.207 Torque Loss + Reversion possibility ( too slow FPS )
Note : these are calculated average Port cross-sectional areas and FPS

--- Cross-Sectional Areas at various Exhaust Port Velocities (@ 28 in.) ---
149 FPS at Exhaust Valve Curtain Area= 2.289 sq.in. at .500 Lift
204 FPS at Exhaust Valve OD Area and at Convergence Lift = .364
252 FPS 90% PerCent Rule Seat-Throat Velocity CSA= 1.350 sq.in. at 6000 RPM
--- 6000 RPM Exhaust Cross-sectional areas in Square Inches ---
435 FPS CSA= 0.783 Sonic Choke at Throat Area (too fast FPS velocity)
380 FPS CSA= 0.897 Sonic Choke at Throat Area (possibly too fast FPS)
350 FPS CSA= 0.973 Exhaust Port has Sonic-Choke with HP Loss (too fast)
330 FPS CSA= 1.033 Exhaust Port has Sonic-Choke with HP Loss (too fast)
311 FPS CSA= 1.096 smallest Exhaust Port ( very high velocity FPS )
300 FPS CSA= 1.136 smallest recommended Exhaust Port (Hi velocity)
285 FPS CSA= 1.196 smallest recommended Exhaust Port (Hi velocity)
265 FPS CSA= 1.286 Recommended average Exhaust Port CSA
250 FPS CSA= 1.363 Recommended average Exhaust Port gasket area
240 FPS CSA= 1.420 Recommended largest Exhaust Port gasket area
225 FPS CSA= 1.515 Largest Exhaust Port Exit gasket area (Slow FPS)
210 FPS CSA= 1.623 Largest Exhaust Port Exit gasket area (Slow FPS)
190 FPS CSA= 1.794 Torque Loss + Reversion + Scavenging loss (too slow FPS)
180 FPS CSA= 1.893 Torque Loss + Reversion + Scavenging loss (too slow FPS)
Note : these are calculated average Port cross-sectional areas and FPS

Erland

[Jens Gustavsson]

den ser ut som om den får väldigt mycket bensin på höga varv men det är svårt att se. du har inte bromsningen i siffer form typ så här?



inte lönt att jaga problem i motorn förens bränsle kurvan är skapligt "rätt"
jag ska lägga upp lite data på en liknade motor i morgon vi bromsat för några dagar sen. den gav ca 212 hk/242nm med enem K25 kam/37mm, 14mm lyft ca 270 grader/1.25mm.

för att va lite tvärs imot erland så säger jag att det inte är så mycket lyftet som begränsar vid de effekterna. men klart större aria med 37 tryckare skulle göra mer effekt men inte så mycket. som sagt soppa kurvan ser konstig ut?

mvh jens

[Erland Cox]

Är du inte sugen på att ställa upp i 531 topps bromstävlingen Jens om vi nu lyckas få till den?
Då har du ju möjlighet att se hur långt dina teorier och idéer räcker samt se andras lösningar.
Det jag håller på och plockar ihop är absolut ingen värsting utan en standard 230 bottendel
med en osvetsad topp som inte heller är flyttad i sidled med 48-40 ventiler.
Tanken är att det ska bli en testmula för lite kammar, grenrör och annat.
Jag har hittat en hyfsat fin 244GL (förgasare) att stoppa ner motorn i.
Håller på med bussningar och fjädring på bilen och toppen till motorn.

Erland

[Erland Cox]

Like Jens said your AFR is going really fat with increasing RPM.
What emulsiontube and jetting are you using?
A bigger air jet will help you get a more even AFR reading.

Erland

[Panu]

Thanks for replies.
Yes AFR is really rich on high revs. Dynotester was busy on that day and he had not much nerves to adjust anything. Maybe try some other place next time.
Now I'm little bit ashamed I didn't notice this mixture earlier.

I cannot remember what tubes or air jets I have. I'll check it today and buy bigger air jets. Maybe I'll mount temporarily MS-efi for datalogging purpose and go to test track for adjusting mixtures.

Selection of camshaft was made because of the original lifters. Maybe there is a chance to have little bit more lift with original lifters or then I'll need to change lifters with adjust on downside if I want to have more aggressive cam.

[Erland Cox]

You can adjust the carbs on the road with butt feeling bot it is even better if you get a lambda to check so you don't lean out.
AFR seems to be OK up to 6000 rpm so maybe 2 steps bigger air jet will fix it.
From 160 to 170 for instance.
Do a full throttle pull and immedeately turn of the engine and check the plugs.
With pump gasoline they should be light brown and the ground strap must not look like it has been very hot.
If it starts bkuing and rounding of the tip you are too lean.
You are also very lean at the bottom so my guess is that you have F16 emulsion tubes, in that case try F9:s.

Erland

[Panu]

Actually this engine is on Rallycross Ascona so I need to go tuning to RC track. I have wideband O2 gauge so mixture checking is easy.

Anyway I checked jets today. F16 emulsion tubes and 170 mainjets. Unfortunately air jets are soldered and drilled so I cannot say what those are. Need to get some tools to ensure what size those are. Or just buy 190 and 200 jets and try those.