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| flyboy | factory horsepower ratings | ||
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Elite Guru
 
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In 1975 the auto makers went to rear wheel h.p. ratings in part I believe to appease the govt. and insurance (the ratings were around 20% lower and it showed on the corvette 190+250 in 74 to 165+205 in 75. A couple years ago they went back to gross (flywheel) #'s. I really don't see a corresponding jump in corvette ratings, s/b about 20% unless it was 2005 when they went from 350 to 400. Can anyone enlighten me on this?
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Posted on: 2008/11/12 3:01
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| bogus | Re: factory horsepower ratings | ||
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Grand Imperial Pooh-Bah
 
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oh... we need to clarify some stuff.
The SAE ratings have ALWAYS been done at the crank... never at the rear wheels. The change you are referring to occured in 1972, they went from SAE gross to net. The difference was that net includes accessories and a full exhaust system. In addition, emissions started to come into play and compression ratios dropped to deal with the lower octane unleaded fuels. Gross was so lax that the tests included water pumped through the engine by a standalone pump, not the engines belt driven pump. That is what caused the drop. I don't think it was attributed to insurance complaints, but to run-a-way horsepower wars, more or less based on lies. What happened a couple of years ago was a refinement of the SAE procedure. The lowering of power from 1974 to 75 had to do with emissions and such. To put it into perspective, a friend had a 1971 Mustang Mach 1. It had a base 2bbl 302ci V8, which was rated at 210hp. The SAME EXACT engine was rated at 140 in 1972. The only change I am aware of was the addition of hardened valve seals to deal with unleaded fuel. That is what the rating process changed. For the most part, the most recent change resulted in small drops... 5~10hp or so. |
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Posted on: 2008/11/12 3:22
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| CentralCoaster | Re: factory horsepower ratings | ||
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Senior Guru
 
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And it's a good change. But the old farts will still tell you about their 15-second Chevelle that had 400 hp.
The certifications were updated recently to be more accurate, not sure if all the manufacturers are using them though, Corvette is. |
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Posted on: 2008/11/12 4:48
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| bogus | Re: factory horsepower ratings | ||
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Grand Imperial Pooh-Bah
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All US based manufacturers are using it.
When I say that, I mean companies that build here. Which, it seems, excludes the big three anymore... |
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Posted on: 2008/11/12 5:45
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| 88BlackZ51 | Re: factory horsepower ratings | ||
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Senior Guru
 
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My 88 was dynoed bone stock. It made 211rwhp(yeah i know), but it made 318 rwtq. I was suprised that it made that much TQ. In my opinion the L-98, or at least my motor was underrated in the TQ department.
My new motor should be in the area of 460rwhp in the same chassis. Ouch! I find it humerous that the old timers including my father talk about the old days, and how FAST the cars used to be. I admit the odd big block was very fast, but we are living the big HP days right NOW! |
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Posted on: 2008/11/12 7:12
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| bogus | Re: factory horsepower ratings | ||
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Grand Imperial Pooh-Bah
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it's hard to quantify rwhp, vs chp. The best we can do is guess... but it gets worse than that, no 2 dyno's measure the same. There are SO many variables... engine temp, driveline temp, air conditions, when was the last pull? Meaning, dyno conditions/temp.
When the manufacturers test, they use river water to keep the dyno at a constant temp, and the air temp is fixed, too. I don't know all the specs for the SAE standard, but they are there and are there to create a standard. This is why dyno numbers are such a joke... One dynojet might give one 320hp and 375 ft-lbs, but the mustang down the street might give 290hp and 345 ft-lbs... see? There is no standard for those units... I have a very small dyno, it's used for RC car motors. Battery powered, that is. This unit uses a fixed slave and will present a wattage number depending on amp loading and RPM. They suggest three pulls, because that takes coolness out of the equation. I know that the numbers drop with each pull. You then take the averages. The dyno is a Competition Electronics Turbo 30 Dyno. If RifleCoach is paying attention to this thread, CE makes various ballistic measuring devices, too. And yes... only a FEW of the 50s and 60s muscle cars lived up to their inflated numbers. Just about all the Hemi's... The 427 side oiler, high compression 427 chevy BB's... Pontiac SD motors... the GM 302 in the Z28... thats just a few, the rest were bad marketing. |
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Posted on: 2008/11/12 15:40
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| 65Z01 | Re: factory horsepower ratings | ||
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Guru Newb
 
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I put my C4 on a DynaJet just after some consistent passes at the strip and found that the DT loss with my A4 was 17%. I've read that with a stick shift one could expect around 15% DT loss.
My C4 had been on two DynaJets about 2yrs apart and the pulls were rather close indeed, though the latter power curves had been extended somewhat due to engine mods. I have heard that the Mustang dyno will give substantially different torque/HP values from the DyanJet though. |
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Posted on: 2008/11/12 18:40
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| CentralCoaster | Re: factory horsepower ratings | ||
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Everything I've read says Dynojets are pretty precise because of their simplicity, but not accurate. I would expect more accurate numbers from a Mustang dyno, but it depends more on the operator. Too many bells and whistles to affect the results.
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Posted on: 2008/11/12 18:48
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| CentralCoaster | Re: factory horsepower ratings | ||
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Quote:
How do you figure? You can't measure the flywheel HP and the rear wheels on the same dyno. I think stating % losses for transmissions is a misnomer, I would expect the drivetrain losses to be less than double at 5000 rpm for a motor was making 500hp vs one making 250hp. |
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Posted on: 2008/11/12 18:52
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| Schrade | Re: factory horsepower ratings | ||
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Elite Guru
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NEW motor? A 20 year old L98 that has 211 is VERY good. It is obviously in excellent condition and has a GOOD burn and tune. I would NOT pull that motor. |
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Posted on: 2008/11/13 2:32
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| Schrade | Re: factory horsepower ratings | ||
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Elite Guru
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Quote:
Welcome to the boards 65z01... Get tired of dodgin' all the mud-slingin' in CF? Schrade... |
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Posted on: 2008/11/13 2:36
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LT5, Marc Haibeck ECM module, AUTOMATIC!!!
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| bogus | Re: factory horsepower ratings | ||
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Grand Imperial Pooh-Bah
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So, flyboy, did we answer your question ok?
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Posted on: 2008/11/13 2:39
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| 88BlackZ51 | Re: factory horsepower ratings | ||
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Senior Guru
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Quote:
It's a bone stock motor. My best is a 13.6x@102. I will be selling it next year, or putting it on a engine stand for a conversation piece in my garage. From what I have seen it's a very green running motor. I have't seen very many people run a 13.6 with a stock L-98 with a 1.95 60 foot. |
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Posted on: 2008/11/13 3:01
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| flyboy | Re: factory horsepower ratings | ||
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Elite Guru
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Thanks for the clarification, bogus.
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Posted on: 2008/11/13 3:07
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| 88BlackZ51 | Re: factory horsepower ratings | ||
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Senior Guru
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Quote:
You answered it first. Thanks. |
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Posted on: 2008/11/13 3:09
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| CentralCoaster | Re: factory horsepower ratings | ||
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I don't think that's anything unusual. My conclusion is that most everyone else just can't drive what they have. My best was 13.79@100.4 w/ 2.01 60', SAE corrected to 13.67@101.3. I don't even know what mine is capable of since I have only 6 passes on the 1/4. 99% of my stuff is at the local 1/8th mile. One of these days I'll dyno it. |
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Posted on: 2008/11/13 15:43
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| 88BlackZ51 | Re: factory horsepower ratings | ||
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Senior Guru
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I don't know about you, but I havent seen very many trap 102 with a stock motor. I have 3 friends with L-98, and they had a few other minor mods, and I was always trapping the highest mph when we went to Cayuga Motorsport Track. I have seen a few on the forum trapping in the 104-105 area but they had roller rockers, pulleys etc..... I still thought 102 was good with only mod being exhaust, and the shitty flowmaster 2.25" catback to boot! |
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Posted on: 2008/11/13 15:51
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| CentralCoaster | Re: factory horsepower ratings | ||
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Senior Guru
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Mine's not technically stock as I've ported the plenum and put a cold air intake and new exhaust after the stock Y pipe. The drivetrain is basically all 89 stuff.
65Z01 I think had some killer times on his stock 88. What was your 1/8th mile on that run? Did you put it in the timeslip thread? I like seeing good times on stock engines on there. |
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Posted on: 2008/11/13 15:56
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| 88BlackZ51 | Re: factory horsepower ratings | ||
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Senior Guru
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Quote:
I will have to dig it up. Give me some time! Jim had a few mods as well.......Jim isn't running as strong these days. I think his ole' L98 is getting tired. I thought his car ran a 14.3x or something to that accord when it was stock at 96-97 mph. Not really that good! |
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Posted on: 2008/11/13 17:35
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| CentralCoaster | Re: factory horsepower ratings | ||
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Senior Guru
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He posted a 13.50 at 101 on the timeslip thread, says it was stock. But that was at the magical Etown track that is built in the bottom of a mineshaft.
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Posted on: 2008/11/13 18:22
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| 88BlackZ51 | Re: factory horsepower ratings | ||
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Quote:
If you must: http://www.geocities.com/jgkov/35Anna.html Jim wasnt stock at 101 mph. Auto's dont trap as high from what I have seen in person. |
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Posted on: 2008/11/13 18:31
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| CentralCoaster | Re: factory horsepower ratings | ||
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Senior Guru
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Busted! Maybe I'll banish him from the list.
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Posted on: 2008/11/13 18:32
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