12-08-2021, 10:02 PM
(This post was last modified: 13-08-2021, 08:25 AM by Bob Culver.)
Several years ago Alan unearthed a 1935 iMechE paper from Austin Co giving bhp. At 2200, 2400,2600,3000,3200,3500 11,12,12.5,13.5, 13.7, 13.4.(calc torque 26,26,25,23 1/2, 22 1/2, 20 lbsft.)
For a 1937 Thetis marine with possibly similar manifold but water cowled, 12.1,13,14, 15.4, 15.8,16.3
Further, the Thetis 800 3.8,1200 6.2, 1600 8.8, 2000 11.1 ,3600, 3800 16.4
Thetis torque 800 26, 1200 27.5 1600 28.5, 2000 29.5, 2200 29, 2400 29, 2600 28, 3000 27, 3200 26, 3500 25, 3600 24, 3800 22.5
By way of comparison A30 at 2400 40 ibs ft and 18bhp, at 3200 37, 23 at 3600 36, 25 at 4800 30lbsft 27.5bhp.
. OHV and high comp.
(As hp is torque x revs and torque is hp /revs can draw own curves
HP/revs X 5252))
My stock RP speedo read slower than other cars so was probably accurate. On dead level in dead calm would attain 50 mph but fell off rapidly as carbon formed. Removed and instantly recovered. Suggests breathing restriction so the earlier low comp head may have had more top end hp. Incidentally I drove 60 miles most weekends to my home town. Most would assess the road as about 50% flat; in fact only about 4 miles were! (Wellington-Levin. The Paekak waterfront level)
The top speed was little improved with later head and SU but hill climbing in 3rd hugely improved (at rate where wind resiatance less dominating)
Note the 4.9 3 speed cars in 2nd closely match the 5.25 in 3rd
Amended to correct tThetis torque figures (graph very small and my eyes old)
For a 1937 Thetis marine with possibly similar manifold but water cowled, 12.1,13,14, 15.4, 15.8,16.3
Further, the Thetis 800 3.8,1200 6.2, 1600 8.8, 2000 11.1 ,3600, 3800 16.4
Thetis torque 800 26, 1200 27.5 1600 28.5, 2000 29.5, 2200 29, 2400 29, 2600 28, 3000 27, 3200 26, 3500 25, 3600 24, 3800 22.5
By way of comparison A30 at 2400 40 ibs ft and 18bhp, at 3200 37, 23 at 3600 36, 25 at 4800 30lbsft 27.5bhp.
. OHV and high comp.
(As hp is torque x revs and torque is hp /revs can draw own curves
HP/revs X 5252))
My stock RP speedo read slower than other cars so was probably accurate. On dead level in dead calm would attain 50 mph but fell off rapidly as carbon formed. Removed and instantly recovered. Suggests breathing restriction so the earlier low comp head may have had more top end hp. Incidentally I drove 60 miles most weekends to my home town. Most would assess the road as about 50% flat; in fact only about 4 miles were! (Wellington-Levin. The Paekak waterfront level)
The top speed was little improved with later head and SU but hill climbing in 3rd hugely improved (at rate where wind resiatance less dominating)
Note the 4.9 3 speed cars in 2nd closely match the 5.25 in 3rd
Amended to correct tThetis torque figures (graph very small and my eyes old)