Rolling Road outcome

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Damson6
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Joined: Tue Jul 28, 2020 8:11 pm

Rolling Road outcome

#1 Post by Damson6 »

Thanks to all the help I have had from members and also gaining a lot of information from the forum.
Now that the engine (Sprint) is run in and going well I thought I would update on the outcome now it has had it's rolling road session.
The engine is as follows.
Nothing radical and pretty much standard as regards engine internals but the flywheel has been slightly lightened and crank etc. all balanced.
The camshaft fitted is a
Newman PH3 Fast road / Rally
290 duration
Valve lift 0.390 (9.9)
35 75 75 35
Twin Weber 45DCOE's with 36mm chokes
Jetted Mains 130, Air 160 and emulsion tubes F4.
Max Engine BHP 153 and 119 at the wheels at 5495. Power tailing off at 5500rpm.
Max torque 151 lbf ft at 5100 but pretty much a flat curve from 4200 to 5400rpm
Due to the fact I had points (not cheap Ebay ones) fail I fitted a left over Accuspark electronic ignition from a 1500 engine I used to have, optimal timimg was 28 degrees

So I'm really pleased with how it has turned out and look forward to having a blast!

Derek
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soe8m
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Re: Rolling Road outcome

#2 Post by soe8m »

The average Sprint has about 105 at the rearwheels so 119 is a big improvement. Unless the engine was out and on a dyno also the 153 engine power is a bit overexited.

Loosing 34 hp on the transmission would melt the alloy gearbox casing and you not being able to even tough the gearlever.. around 135 engine hp would be a more accurate figure when you have to guess something.

35hp loss are Landrover series figures with extra transfer cases and agricultural diffs.

Jeroen.
Classic Kabelboom Company. For all your wiring needs. http://www.classickabelboomcompany.com
Damson6
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Re: Rolling Road outcome

#3 Post by Damson6 »

soe8m wrote: Sun May 29, 2022 5:41 pm The average Sprint has about 105 at the rearwheels so 119 is a big improvement. Unless the engine was out and on a dyno also the 153 engine power is a bit overexited.

Loosing 34 hp on the transmission would melt the alloy gearbox casing and you not being able to even tough the gearlever.. around 135 engine hp would be a more accurate figure when you have to guess something.

35hp loss are Landrover series figures with extra transfer cases and agricultural diffs.

Jeroen.
The rolling road man has the loss down as "Drag Power" ? It is a newly rebuilt Sprint gearbox though, also has an LSD.
Wouldn't the transmission losses be more than 15 BHP?
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soe8m
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Re: Rolling Road outcome

#4 Post by soe8m »

You can measure the loss not totally accurate that way but it gives an indication. Running a negative dynorun where the dyno calculates how much hp it costs to 'run the transmission'. It should be done at full speed and then put the car in neutral and let it roll out to standstill.

At you car it shouldn't be near 34hp. I actually did 'measure' a landrover series this way after fitting a compressor and the loss was around 35hp at that car.

A healty Sprint should have a loss of around 15 hp with a max of 20. A faulty wheelbearing or play in an propshaft UJ can add 5+ hp to the loss measured on such a negative dynorun.

It isn't a fixed percentage as a lot do calculate their own 'must be' engine power. A 600 hp car loosing 20% by transmission....

A dyno is adjustable at many parameters and some adjust to the most positive. Enginebuilders who dynorun their own products have those habits the most. A high outcome does have the bill paid more easily by the customer.

When 34 hp loss at your car is the actual loss measured at a negative dynorun you should investigate where the loss is as when solving the cause there's a lot to gain at the wheels again..

Jeroen
Classic Kabelboom Company. For all your wiring needs. http://www.classickabelboomcompany.com
Damson6
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Posts: 18
Joined: Tue Jul 28, 2020 8:11 pm

Re: Rolling Road outcome

#5 Post by Damson6 »

soe8m wrote: Tue Jun 07, 2022 2:22 pm You can measure the loss not totally accurate that way but it gives an indication. Running a negative dynorun where the dyno calculates how much hp it costs to 'run the transmission'. It should be done at full speed and then put the car in neutral and let it roll out to standstill.

At you car it shouldn't be near 34hp. I actually did 'measure' a landrover series this way after fitting a compressor and the loss was around 35hp at that car.

A healty Sprint should have a loss of around 15 hp with a max of 20. A faulty wheelbearing or play in an propshaft UJ can add 5+ hp to the loss measured on such a negative dynorun.

It isn't a fixed percentage as a lot do calculate their own 'must be' engine power. A 600 hp car loosing 20% by transmission....

A dyno is adjustable at many parameters and some adjust to the most positive. Enginebuilders who dynorun their own products have those habits the most. A high outcome does have the bill paid more easily by the customer.

When 34 hp loss at your car is the actual loss measured at a negative dynorun you should investigate where the loss is as when solving the cause there's a lot to gain at the wheels again..

Jeroen
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