What will a leakdown test tell me?
#31
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My dyno #s were at the wheels? Something is sticking in my head about the tranny looses 15 percent, so the dyne guy thought my cup piprpe and chip must have incread my numbers.
As you probably know, my rsa was rated at 247 hp fm the factory...is that # fm the wheels or adjusted?
As you probably know, my rsa was rated at 247 hp fm the factory...is that # fm the wheels or adjusted?
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Here's a link to a utube video done by performanceautosports.com showing my RSA being dyno'd...
its the first video if the link doesn't work...don't know how to imbed the utube video into this post...enjoy!
its the first video if the link doesn't work...don't know how to imbed the utube video into this post...enjoy!
#33
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"But once you've got everything apart anyway, it's only a couple of minutes per cylinder."
Sure, if you've got the compressor and the leakdown tester...but, if someone's paying for a PPI and they got good, even compression, my point is why go to the extra expense? At, say 170-175 psi/ cyl, you're not going to see bad leakdown numbers.
Sure, if you've got the compressor and the leakdown tester...but, if someone's paying for a PPI and they got good, even compression, my point is why go to the extra expense? At, say 170-175 psi/ cyl, you're not going to see bad leakdown numbers.
#34
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Auto factories (and some builders) use engine dynos, which are far more accurate and predictable than chassis dynos. The numbers provided are AT THE FLYWHEEL, not at the wheels.
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Thx Steve...
The dyno shop stated the numbers are to the ground (rear wheels). Is it just semantics...play on words?
Can you explain so I can understand the difference?
Also, do you know how the factory measures HP ratings?
Any insight would be appreciated and will certainly help the p-car new guys...
Thx!
Phil
The dyno shop stated the numbers are to the ground (rear wheels). Is it just semantics...play on words?
Can you explain so I can understand the difference?
Also, do you know how the factory measures HP ratings?
Any insight would be appreciated and will certainly help the p-car new guys...
Thx!
Phil
#36
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Thx Steve...
The dyno shop stated the numbers are to the ground (rear wheels). Is it just semantics...play on words?
Can you explain so I can understand the difference?
Also, do you know how the factory measures HP ratings?
Any insight would be appreciated and will certainly help the p-car new guys...
Thx!
Phil
The dyno shop stated the numbers are to the ground (rear wheels). Is it just semantics...play on words?
Can you explain so I can understand the difference?
Also, do you know how the factory measures HP ratings?
Any insight would be appreciated and will certainly help the p-car new guys...
Thx!
Phil
Please don't confuse me with an actual expert in this area. But that never stops me.
Your chassis dyno run recorded 243 HP... that is to the wheels, or "to the ground". Chassis dynos have lots of variables, and it very difficult to compare one against another. They are very useful for recording differences after modifications... on the SAME dyno. The number can vary by 10% or more from one dyno to the next. All dynos (engine or chassis) factor in a correction factor for some SAE standard temperature and humidity. Chassis dynos do NOT try and factor drive-train losses to determine engine HP, but your guess of a 15% loss is probably realistic.
So, assuming your chassis dyno is fairly accurate, and 15% is a good guess for drive-train loss, your 243 "to the wheels" would translate to approx 279 HP at the flywheel. This represents a nice gain over the 247 HP claimed by the factory.
#37
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"But once you've got everything apart anyway, it's only a couple of minutes per cylinder."
Sure, if you've got the compressor and the leakdown tester...but, if someone's paying for a PPI and they got good, even compression, my point is why go to the extra expense? At, say 170-175 psi/ cyl, you're not going to see bad leakdown numbers.
Sure, if you've got the compressor and the leakdown tester...but, if someone's paying for a PPI and they got good, even compression, my point is why go to the extra expense? At, say 170-175 psi/ cyl, you're not going to see bad leakdown numbers.
Back to the original point though. You're paying for a PPI. If *I* were doing it, I'd tell the customer it's an extra 1/2 hour labor (to be GENEROUS) to also do the leakdown. And I'd guess any shop will have the compressor and leakage tester.
When all the RSAs rolled out into competition in the early '90s, seemingly EVERYONE said they were getting 300HP with a little of this/little of that. Odd how my club racer that still had the cat on it, in stock class, never lacked for trap speed when I got around to running my own 7-8 years later. (Granted, we didn't have data, but I took exhaustive notes on RPM v. point on track for all my customer cars and mine.)
#38
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