I know that this has been over 100 times before but I had nothing better to do this morning and was going over stock L98 numbers (1992).

How could a car with an auto trans be making 245 hp at the flywheel and still be putting down 210-215 hp at the wheels? If you go by stock flywheel numbers and stock wheel numbers, it only comes to about a 13% power loss. At the accepted % loss of 18%, to make that power at the wheels, it would need about 260 hp and 365 torque at the flywheel to come up with 212 hp and 303 torque at the wheels.

Or if you use 20%, 265 hp and 378.5 fp torque at the flywheel.

Not to mention the dual cat option adds a little more on top of that.

 

easiest question of the day...
because of the vette
camaro ratings are always underrated
it's the same engine in the vette, and i forget what power the vette was making by then
save for the aluminum vs. iron heads, all of it was the same i believe
so, in short, the vette made the ratings get lowered
also, the ratings may be lower too, even for the vette, because of insurance companies charging higher rates for higher hp cars

 

How did you come up with the 210/215 RWHP numbers?????
They should be about 196 RWHP on a stock L98 in 1992.

 

From what I have seen, a pure stock L98 in 92 will dyno 210-215 hp and 300-305 fp torque.

 

I remember a guy on here dyno'd his stock L98 and put down 212 rwhp. I think his name was stanghunter211 or something. Anyway, from what I've read, the L98's are underrated. There's long thread about it, just search for L98 underrated.

-Corey

 

I know there was a thread on that - I started it. The only thing that I really got out of it was a bunch of guys with LT1's that came over and all they did was bash the L98 to make their engines look better.

 

Whoops.

 

I did look back on that thread. If i use the RW numbers that were supplied, 214 RWHP and 315 RWTQ, using a 18% drivetrain loss, I came up with 261 HP and 384 TQ at the flywheel.

Now, the HP numbers are believable considering the only difference between this engine and the C4 engine were the heads. The only difference there were the materials used. On the other hand, I have a hard time believing the TQ numbers.

I might believe, at the most, 370 TQ.

 

I don't believe the drivetrain losses are as severe as most think, I've seen numbers of LS1's even that suggest losses are nearly half of accepted rates. I've seen documented losses of only 15HP! thru the Drivetrain...
Plus, as I and others have long stated they underrate our cars to pass govt guidelines. Our ET's and traps are not far off LT1's which puts us closer to their power rating than listed 245hp...Our biggest trouble with slightly slower ET's is our ability to "Hook-up".
There's less chance of dissapointment too by underrating a product..

 

Hey Rippin92RS, thanks for remembering me. My #'s are from my bone stock car, the weekend I bought it. Paper airfilters, not running the best. I mean it was stock. I was surprised myself, a 14 year old car throwing down 312 torque, thats LS1 level. Its entirely possible. I think the 196 rwhp #'s mentioned sound like my friends 92 Z28 LB9.

 

Agreed. I've talked to a few of the more advanced members here who did buildups that included engine dynos and dyno jets. Believe it or not the T56 only looses about 12-13% while the autos are closer to the 18% mark. It's hard to judge the exact numbers for the autos since many have them built with heavy-duty parts and loose convertors.

Anybody have any stock or bolt-on L98 dyno graphs?

 

Take it to another dyno and have it tested. Not all operators know what they are doing.

The couple of stock L98's I've seen dyno were in the 190-200 range.

Also, the exhaust is quite a bit different for the 'Vette. And also the air intake is different. More air in, more air out, more power.

 

when i dynoed my 91 G92 LB9 i got 210/280 at the wheels...

only mods were a K&N, flowmaster and the EGR walls ground down

thats about 250 crank HP and 320-330 ft pounds...not to bad for a little 305 eh?

 

I've seen some dyno sheets that show some F-Body set ups actually out flowed the Vette's, the Vettes trannys had better servo's and more heavy duty parts that help their RW numbers.

From what I've seen about the LT1's, most of the improvements were aimed at moving the Peak Power numbers higher in the RPM band. Such as "shorter intake runners", "taller intake ports", "Swirled combustion chambers", and cam timing to help support it. It makes the power band more "Peaky" tho, killing off some low end torque, which isn't a really bad thing in the "traction department".
Some "improvements" tho have been a thorn in the LT1's side, such as the shorter wheel base, engine location, "Optispark, other than the "Blue-Death", it has been know to self-destruct if it spends too much time above 6000 rpm...
The TPI as it's designed maintains a broader more usable power band/torque curve, and that is what I believe accounts for it's ability to compete effectively with LT1's. It's the "Average" power numbers that really moves the car down the road...
I'd love to be able to plug in a Power Programmer to my ROC and mess with fuel, spark and shift parameters tho.

 

don't we all lmao. it would save us a lot of time and money