How much drivetrain loss can I expect?
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Member
Joined: May 2002
Posts: 364
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Car: 1983 Trans Am
Engine: 355 SBC
Transmission: 700R-4
How much drivetrain loss can I expect?
I am building my new engine, and I did a desktop dyno on it and it reads 420 horsepower at 6000 RPM, and 420 torque at 4250 RPM's. How much drivetrain loss can I expect? How much will actually be sent to the wheels? I figured to myself maybe 20% loss leaving me with 336 to the wheels???? Any help would be much appreciated! Thanks!
Also, 2 more questions. How many liters is a 355? 5.8? 5.85??? And are 3rd Gens lighter than 4th Gens? Thanks!
Steve
Also, 2 more questions. How many liters is a 355? 5.8? 5.85??? And are 3rd Gens lighter than 4th Gens? Thanks!
Steve
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Joined: Jan 2003
Posts: 1,083
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From: Northwestern Pennsylvania
Car: 1985 Pontiac Trans Am
Engine: 355 with stuffs.
Transmission: 700R4
Axle/Gears: 4.10 Posi
Desktop Dyno
I'm not sure about power loss, but I am curious as to where you got the Dyno program... I'd like to find one of those myself. As for a 355, you have a 350 bored .030 over, so in my opinion you have a 5.75 or 5.8L.
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Joined: Jul 1999
Posts: 18,457
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From: Loveland, OH, US
Car: 4
Engine: 6
Transmission: 5
Drivetrain loss is not the same thing as "difference between motor HP and RW HP". The act of installing a motor in a chassis causes all sorts of other issues; air cleaner restriction, exhaust, accessory losses, etc.
I have a friend who owns a chassis dyno, who has a friend who owns an engine dyno. On more than one occasion people had his friend dyno a motor, then they brought the car to the chassis one for tuning. His report is that the smallest difference between the 2 numbers that he ever had seen was 22% (in a stock car that ran at El Cajon), and more typically is was around 28%, and an auto trans street car with a poor intake tract (Firebird TPI, single snorkel, open-element hot-air, etc.) sometimes ran as high as 35% difference.
In short, don't get overly optimistic. Use 28% and you probably won't get disappointed too bad when the real numbers come in.
I have a friend who owns a chassis dyno, who has a friend who owns an engine dyno. On more than one occasion people had his friend dyno a motor, then they brought the car to the chassis one for tuning. His report is that the smallest difference between the 2 numbers that he ever had seen was 22% (in a stock car that ran at El Cajon), and more typically is was around 28%, and an auto trans street car with a poor intake tract (Firebird TPI, single snorkel, open-element hot-air, etc.) sometimes ran as high as 35% difference.
In short, don't get overly optimistic. Use 28% and you probably won't get disappointed too bad when the real numbers come in.
Thread Starter
Member
Joined: May 2002
Posts: 364
Likes: 0
Car: 1983 Trans Am
Engine: 355 SBC
Transmission: 700R-4
Thanks for the info guys! As far as where I got the program, a friend of mine who is a mechanic/engine builder had an extra copy that he gave me. I know you can usually get the program at performance shops or on ebay or something.
Steve
Steve
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Joined: Oct 2002
Posts: 9,067
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From: Saskatoon, SK, Canada
Car: '83 Z28, '07 Charger SRT8
Engine: 454ci, 6.1 Hemi
Transmission: TH350, A5
Axle/Gears: 2.73 posi, 3.06 posi
A Ford 351 Windsor/Cleveland was 5.8L so your 355 is at least that.
Just do this to find the exact displacement of your engine in litres:
engine c.i. / 61 = engine L
ex. 427 / 61 = 7L
Just do this to find the exact displacement of your engine in litres:
engine c.i. / 61 = engine L
ex. 427 / 61 = 7L
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