- Detta ämne har 27 svar, 9 deltagare, och uppdaterades senast 2010-10-15 06:31 av .
- 15 augusti, 2010 kl. 10:13 #161362
OK, so much for the short trumpets, Andrew at the dyno was in no rush to go home and he seemed as interested as me to see what the 90mm trumpets would produce, 5 minutes later the longer trumpets fitted and we’re ready for another run.
Comparing this run with a previous run, with the old manifold and 90mm trumpets, peak power was up by a tad over 6bhp, but this time it kept rising, i told Andrew not to go over 6500rpm, so 166bhp was it’s limit at 6300rpm, maybe we could have reached 170, but in this case i am happy with what i’ve got, a very respectable fast road car :).
Torque also increased, almost throughout the entire rev range and peak torque was up by 6lb/ft.
15 augusti, 2010 kl. 10:15 #161363
To conclude, the smaller primary pipes have made a difference, but the difference was improved further by using the 90mm trumpets. Here is a final graph with the new exhaust manifold comparing the 40mm and 90mm trumpets.
I think with the ultra big valve head and wilder cam a different manifold may be needed altogether. I have since learned about two manifolds available from Sweden,(thanks to Krister for the link) similar in design to what i already have, but with larger pipes, 42mm primary/48mm secondary and 60mm exit pipe, this one is intended for 2150cc rallycross, the other even larger with 44mm primary/51mm secondary and 64mm exit pipe, intended for 2400cc rallycross.
17 augusti, 2010 kl. 10:41 #161391
Just to add some ’meat to the bone’ Dave Baker has added some very useful pages to his website regarding exhaust;
In fact, even if you are slightly interested in engine tuning you should really put some time aside to read the rest of his website http://www.pumaracing.co.uk/index.htm17 augusti, 2010 kl. 11:10 #161392ake svantessonDeltagare
i think i have brake on a old engine that is 202 hp in a h-engine
i see if i can copy them in here,,27 augusti, 2010 kl. 15:40 #161766truls herlandDeltagare
Honour to you Dave for a very respectable work to your engine!
but why is the measurement so uneven?
Truls27 augusti, 2010 kl. 21:39 #161778
I am still working on getting the early part of torque curve flatter-sub 3500rpm.
As you can see from this graph with the red line, the torque is much flatter than the prevoius graph, this is because of the 90mm inlet trumpets and primaries at 39mm and secondaries at 44mm, torque and power was also increased.
The exhaust manifold i am using is from MSS in the US. Both the primaries and secondaries were 44mm in diameter. The lengths of the pipes are also very unusual, primaries are quite normal at 13” but the secondaries are very strange at 30”, engines of this type and tune usually have secondaries at around 16” to 18”, so this is my next modification, hopefully i will have some results tomorrow.
The dip in torque just before 3500 rpm is a result of the cam being ’out of range’ all engines will have a dip like this at some point.
The graph does make it look worse than it really is, the spread of torque from around 2400 to 3100 is only around 8 lb/ft.
31 augusti, 2010 kl. 07:22 #161877
I cut down the long secondaries (30”) to 18” and put the car back on the dyno, again using 40mm and 60mm trumpets, i wanted to use 60mm trumpets also but i couldn’t get them in time, maybe another day.
The results were mixed, i took the revs a little higher this time and at 6700rpm the power was still hanging on, but i lost out on a few lb/ft of torque under 3500rpm.
I have emailed Timos Motor Co in Stockholm for more information on their 99 manifold, i have not had a reply. Maybe someone on the forum already knows the lengths of their primary and secondary pipe?
12 oktober, 2010 kl. 19:33 #163576
Another attempt to find out where the power is dropping on this engine has been carried out, i fitted stronger valve springs to allow it to rev higher, set the limiter at 7600rpm, but it looks as though it needs to rev higher to get the optimum from this engine, but i think i will leave the rev limit at this, after all it’s still running standard pistons and i don’t think the ring lands will take kindly to an 8000rpm beating, i may tweek the map just to get it above 170bhp just for the sake of it 🙂
12 oktober, 2010 kl. 20:31 #163582
kolla in denna länk http://www.youtube.com/watch?v=ATB-CXZRJp4
B-motor 215Hp vid 7200rpm. Max varv 8750Rpm
/Fredrik13 oktober, 2010 kl. 06:57 #163595
Vid sista pullet så slås gaspedalen i botten på 2000rpm & det släpps av vid 8750rpm.
Dock används Weber 45:or & inte K-jetronic
/Fredrik13 oktober, 2010 kl. 19:28 #163625
Do you have any more information on this engine, valve size, camshaft and maybe a dyno graph, how narrow is the power band?13 oktober, 2010 kl. 20:18 #16363115 oktober, 2010 kl. 06:31 #163689
Thanks Fredrik, i contacted Frank a few days ago but no reply so far.
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