Z06Vette.com - Corvette Z06 Forum

quikdoc · 05-18-2002, 04:25 PM

The verdict is in...
I had the car dyno'd today.
Bone Stock (+ filter K&N)

331.6 SAE RWHP
338.6 SAE RWTQ

Calculated back
385 x .86 =331.1 = 14% loss
It should be noted that my pistons were swimming in fuel...waay too rich. So there may be another 8 to 12HP on the table to be had!

My buddy's 02 numbers were:

350.4
360.6

This is my baseline dyno.
FWIW
Doc

Sanford · 05-18-2002, 05:13 PM

Why the loss?

70boss302 · 05-18-2002, 05:18 PM

02 have 20 more hp than an 01, and you just proved something we already knew. Maybe I am just clueless and don't get the meaning of your post?

Bill

quikdoc · 05-18-2002, 05:25 PM

This is due Mechanical loss through the tranny d/l and 1/2 shafts, friction, heat. The rule of thumb is arguably 15%... the range of loss using SAE standards is 12 to 18%.
The 385HP is SAE at the flywheel (industry standard is measured at the flywheel) and we care more about what's making it to the ground

This was discussed on an earlier thread and I said I'd report back after my first ever dyno. My loss looks to be 14% My buddy's 02( same set up) looks to be about 13.8%

Doc

quikdoc · 05-18-2002, 05:28 PM

Bill
the discussion a couple of days ago was about the % of loss... some saying 10% some saying 18% with 15% being the rule of thumb. I said I'd report back on mine and my buddy's 02 ..No you didn't miss anything..I'm just reporting my 1st ever dyno results and the % loss.
Doc

ZO6/Les · 05-18-2002, 06:13 PM

Well to be fair you are not reporting "loss" you are reporting (hopefully) SAE corrected RWHP vs. factory quoted HP numbers and assuming that the factory number is right therefore making the 14% calculation right. I would politely suggest that the only thing you have proven is what your car made on a particular day on a particular dyno. The only way to measure loss is to compare the same motor on an engine dyno, then on the car and compare the results. Even so variations between dyno's, engine temp. etc. play a huge part in these reported numbers.

BTW I truly believe the number is 14-15% as well, just taking a bit of issue with the basis for your conclusion.

Les

quikdoc · 05-18-2002, 06:27 PM

Les,
That's fine.

I'm looking at the "LOSS" generated from using the factory SAE 385HP and the SAE 331 RHWP dyno measure today (apples to apples more or less)

We both know that there is a LOSS.. in the process of getting the power from the front end to the road (physics is physics so to speak aint nuthin free in that realm) The purpose of my report was to follow through on my comittment to report my dyno numbers and to confirm that the LOSS is in the neighborhood of 14-15% as opposed to the 18% +:- calculated by someone else. Nothing more.
Doc

ZeeOhSix · 05-18-2002, 06:45 PM

Quote:

Originally posted by quikdoc

The purpose of my report was to follow through on my comittment to report my dyno numbers and to confirm that the LOSS is in the neighborhood of 14-15% as opposed to the 18% +:- calculated by someone else. Nothing more.
Doc

Yes, I'd say 14~15% is a good "standard" to use on the C5s with manual tranny.

The 18% (if I recall commented by Z0000006) was a "correction factor" %. In other words, 1/0.85 = 1.18 = 18% correction factor. The same thing as saying there was a 15% drivetrain loss.

Example
----------

Car dynos at 344 RWHP (SAE)
344 x 1.18 = 405 BHP
or
344/0.85 = 405 BHP
or
405 x 0.85 = 344 RWHP

These are all examples of a 15% drivetrain loss.

If you want some "hard core" drivetrain loss discussion, go checkout:

http://forums.corvetteforum.com/zerothread?id=295490

I'm ZeeOSix over there.

ZO6/Les · 05-18-2002, 07:13 PM

Doc,

Wasn't trying to stir anything up, and as I said I agree that the actual drivetrain loss in the range of 14 - 15% (for a manual car, 19-20% for an automatic).

Not to keep harping on it but you are making a big assumtion in your 14% number that the factory quoted FWHP is correct, and often times it is not. Remember the Cobra over reporting a few years ago? Also GM have been known to under-report FHWP for insurance reasons. It is for this reason that I say you are reporting measured RWHP relative to factory reported FWHP for an estimated, not measured, loss. ASsuming the factory quotes are right is a big assumption IMO.

Peace.

Les

Quote:

Originally posted by quikdoc
Les,
That's fine.

I'm looking at the "LOSS" generated from using the factory SAE 385HP and the SAE 331 RHWP dyno measure today (apples to apples more or less)

We both know that there is a LOSS.. in the process of getting the power from the front end to the road (physics is physics so to speak aint nuthin free in that realm) The purpose of my report was to follow through on my comittment to report my dyno numbers and to confirm that the LOSS is in the neighborhood of 14-15% as opposed to the 18% +:- calculated by someone else. Nothing more.
Doc

quikdoc · 05-18-2002, 07:14 PM

will do
Doc

**FRC Tom** · 05-18-2002, 08:08 PM

My base line was also 331 rwhp.

ZeeOhSix · 05-18-2002, 08:59 PM

Quote:

Originally posted by ZO6/Les
It is for this reason that I say you are reporting measured RWHP relative to factory reported FWHP for an estimated, not measured, loss. ASsuming the factory quotes are right is a big assumption IMO.

Well, I read on one of the boards just recently that someone piped in and said he had data from engine dyno tests (talking on an engine dyno) on a 2002 LS6 and they where pretty close to rated HP -- maybe 5~8 HP over making them say 413 BHP.

413 BHP x 0.85 = 351 RWHP which is pretty damn close to what the majority of the guys are seeing on the dynos for 2002 Zees.

I'd still say the 15% is a good standard to use for a manual tranny C5. Of course as mentioned, you would have to rip the engine out to get FWHP then put it back in for RWHP and calculate the loss ... but who wants to do that?

ZO6/Les · 05-18-2002, 09:07 PM

Remember - my starting point is that I agree with the 15% number (always have) and using that formula my car bone stock made 413.8 FWHP. Of course no one would rip out a motor to prove the point, but as I said I will very soon have a comparison on my Trans Am motor of engine dyno vs RWHP. I fully expect it to be in the 15% range.

Time for bed - g'nite.

Les

Quote:

Originally posted by ZeeOhSix

Well, I read on one of the boards just recently that someone piped in and said he had data from engine dyno tests (talking on an engine dyno) on a 2002 LS6 and they where pretty close to rated HP -- maybe 5~8 HP over making them say 413 BHP.

413 BHP x 0.85 = 351 RWHP which is pretty damn close to what the majority of the guys are seeing on the dynos for 2002 Zees.

I'd still say the 15% is a good standard to use for a manual tranny C5. Of course as mentioned, you would have to rip the engine out to get FWHP then put it back in for RWHP and calculate the loss ... but who wants to do that?

quikdoc · 05-18-2002, 09:16 PM

Thanks Tom
I find that somehow reassuring. As I said. the A/F was super rich at WOT and the tuner felt I could capture perhaps another 8-12 HP.
Even my buddy;s 02 was rich but not off the chart as mine was.

The tuner will be buying a new 5 wire unit to handle C-5's and Z's
Doc

**FRC Tom** · 05-18-2002, 09:25 PM

Doc, my AFR is also rich at WOT 11.5.
You can see it in my dyno sheet in my sig.
The back of my car is always spotted in black.

Tom