Anybody have RW dyno figures on L98?

[marine1975]

I was just looking at another thread on the horsepower ratings for the L98's and was wondering if anybody has put their L98 on a Rear Wheel Dyno? My reason for asking is the same that someone mentioned in that other thread - my 87 seems to have quite a bit more than the rated 240hp. I am sure there is someone out there that has dyno'ed a basically stock L98......So what are the numbers?

 

[Vettefan87]

Mad-Mic put his 87 on the dyno with a few mods, he blew his EGR out and I think he pulled somewhere around 250 RWHP, and 345ft pounds of torque. Do a search and you might find exactly what he said, but they are close. Hope this helps.

 

[Mad-Mic]

I was just looking at another thread on the horsepower ratings for the L98's and was wondering if anybody has put their L98 on a Rear Wheel Dyno? My reason for asking is the same that someone mentioned in that other thread - my 87 seems to have quite a bit more than the rated 240hp. I am sure there is someone out there that has dyno'ed a basically stock L98......So what are the numbers?

*Posted on another thread but here *

Mods listed at the time of Dyno run on a Heffners Dynojet

http://www.heffnersperformance.com

K&N open air box, MAF descreened, TB Bypassed, 160* T-Stat, Accel Super Coil, 12* degree advance timing, TPiS Long Tube Headers, airfoil, !EGR, and dumps off the rear Y pipe. Hayden Tranny cooler. Stock 1600 rpm stall, 2.59 rear gear on 275/40/17" BF Goodrich Drag Radials.

the car made 40 more hp and 58 lbs of torque at the fly wheel if you go by a 17% loss but i believe with the 4 additional u-joints its more like 20% which would be 47 HP and 69 toque at the flywheel. this was on only 1 pull due to a blown EGR connection on #8 cylinder and over 220 degrees water temp. with these problems the car still pulled the 235 rwhp and 345 lbs of torque. i'm sure the car could of pulled atleast 20-25+ more hp and torque if the car was cooled down and the egr connection didn't blow and lose all back pressure on #8 cylinder. i think thats a conservative guess due to loosing .2 at the track between cool 140-160 water temp and anything above the 180 range thats what i lose when i've hot lapped the car numerous times.

with these same mods with out the headers and with a catless front Y pipe, the car ran a best of 13.26 @ 103 mph with a 1.83 60' time. best 60' with out the headers was a 1.81 on street tires. this setup was maxed out as far as i'm concerned so there is potential to run some pretty good numbers with just some basic mods with out sinking money into headers. with true duels you might see another tenth or 2 with out headers. the primaries on the stock manifolds is 1 1/8". on my TPiS it's 1 3/4". Big difference when it comes to making HP.

haven't had alot of track time to back up the header install and a few more additional mods like DR's, crank pulley, air elim pulley, and cut back plugs but with just the headers alone i picked up close to 3 mph at 1000' more DA. this would equate to another mph if i was at the same DA i ran the 13.26 with out the headers if every 1000' of DA is .1 and 1 mph which = 10 rwhp on 12.0 and slower cars.

will be dynoing the car again soon to get some better #'s but as you can see a good free flow exhaust can pick up a good bit. 3 mph is = to 30 rwhp from the headers only. i seen many dyno runs from LS1 cars and headers alone average 22 rwhp so this is pretty consistant from what i hear about L98's

 

[Heavy Duty]

I too have often wondered about the HP rating on the early C-4s. Last March i took the tour of the Corvette plant and I asked the BIG question to the tour guide. He seemed to know what he was talking about. The story is that back in the early eighties Corvette was advertising the low HP numbers to make EPA happy. But in reality they where putting out more than advertised. He said that from '85 on up, the L98 to should around 300HP at the flywheel. That would come close to the seat of the pants guess.

I know that my '99 Rustang is suppo to be 260 horses but the '86 (230 advertised) will run rings around it. So...either Ferd has seriously over rated the HP of the stang or Corvette is seriously under rating the L98. Someone isn't telling the truth . What do you guys think. Was the tour guide blowing smoke or on some drugs?

H.D.

 

[ZumZum]

I think the factory HP numbers are correct or only slightly understated. The thing to consider with the L98 is that the engine puts out gobs of torque at lower rpms (where you do most of your driving and usually need the power). When the motor gets up to the 3500-5000 rpm area (where you do less of your driving) the torque falls off. I believe this is why it feels like more ponies than the factory rating.

 

[OLDCHEV]

I have smoked quite a few late model Mustangs and even the supercharged ones with my stone stock L98 Vert. From a complete stop on dry asphalt, I cannot break my tires loose. They are right on the verge of smoking but, the combination of a superior rear suspension and the large footprint of the tires is what beats them (they cannot get enough tire under the fender wells)!

I can look in my rear mirror and see huges clouds of smoke from the Mustangs! By the time they hook up I am usually at the speed limit and backing off. If they catch me moving at or near the speed limit I do not even try as they can smoke me unless we are on a stretch of road that will support 100 MPH+ which they will usually chicken out at about 125+ as their old style suspension scares the S++T out of them and I can cruise up to 150 easily!

Bye the way, the REV limiter (computer) in the stock Corvette for my year (1990) limited me to 167 MPH on a stretch of flat, clear Nevada highway (it kept shutting off the fuel pump). Will not ever do it again but, I had to check what the limits where with this sweet car!

 

[G Winter]

Bye the way, the REV limiter (computer) in the stock Corvette for my year (1990) limited me to 167 MPH on a stretch of flat, clear Nevada highway (it kept shutting off the fuel pump). Will not ever do it again but, I had to check what the limits where with this sweet car!

The computer has a rev limiter ?? at what rpm ? I have had mine on 5800 and still going.

 

[vetteboy86]

Okay I ran my car on the first G-tech meter I bought. I ran a couple of runs stock, with nothing on the car mod wise. It showed rwhp readings of 258 and 266. I also ran 0-60 however not on the same day. Those times were 5.64 and 5.58. I thought those were pretty good considering my car is almost 20 years old. I am going to run it again this spring and see.

I also raced my buddy in his dads 2001 Mustang GT. I am not sure what those are rated at but is wasnt enough

Craig

 

[Edmond]

Craig,

That comes out to more than 300 at the flywheel if you do the calculations. Just take what you got from the Gtech and divide it by .20 for the 20% loss from flywheel to rearwheels.

That's pretty good!

 

[vetteboy86]

Edmond, I really didn't even think about that. Thanks for bringing that up. I wonder if that is really possible. I haven't heard any disclaimers for those meters. I am pretty sure my bro produced numbers close to those as well, so at least it is accurate.

Craig

 

[Heavy Duty]

Okay I ran my car on the first G-tech meter I bought. I ran a couple of runs stock, with nothing on the car mod wise. It showed rwhp readings of 258 and 266. I also ran 0-60 however not on the same day. Those times were 5.64 and 5.58. I thought those were pretty good considering my car is almost 20 years old. I am going to run it again this spring and see.

I also raced my buddy in his dads 2001 Mustang GT. I am not sure what those are rated at but is wasnt enough

Craig

What is a G-tech meter? So are you saying that the car was bone stock when you did the runs? If it is bone stock all I ave to say is "holy Crap Batman. This Batmobile is really fast". Those are some wild HP numbers.

H.D.

 

[Heavy Duty]

I have smoked quite a few late model Mustangs and even the supercharged ones with my stone stock L98 Vert. From a complete stop on dry asphalt, I cannot break my tires loose. They are right on the verge of smoking but, the combination of a superior rear suspension and the large footprint of the tires is what beats them (they cannot get enough tire under the fender wells)!

I can look in my rear mirror and see huges clouds of smoke from the Mustangs! By the time they hook up I am usually at the speed limit and backing off. If they catch me moving at or near the speed limit I do not even try as they can smoke me unless we are on a stretch of road that will support 100 MPH+ which they will usually chicken out at about 125+ as their old style suspension scares the S++T out of them and I can cruise up to 150 easily!

Bye the way, the REV limiter (computer) in the stock Corvette for my year (1990) limited me to 167 MPH on a stretch of flat, clear Nevada highway (it kept shutting off the fuel pump). Will not ever do it again but, I had to check what the limits where with this sweet car!

I haven't had the chance to spank a stang yetin the C4. But the C4 does have a few ricers and one Dodge hemi pickup to it's credit. The guy in the Hemi was really funny. As I was leaving him in the dust from the stop light, all I could see was blue tire smoke and the guy beating the dash of the truck:L. Sad thing is he asked for it by calling my vette a fiberglass peice of S***. I showed him what a real peice of s*** it is and the rear tires never broke traction. I try not to break traction because all that torque has got to be hard on the drive train with the extra wide tires. Not to mention I hate buying tires. This last set was unreal expensive.

As I stated earlier, I do own a '99 Mustang GT and my of the seat of the pants tells me that the vette would my the pony car look like it is going backwards. Maybe I've got a sick pony. Both cars are stock and yes the L98 is a torque monster.

H.D.

 

[OLDCHEV]

Not a rev limiter, a SPEED limiter. I have been told they were set at the factory and it varies as to what tires/suspension package was on the car when it left Bowling Green.

My car has the soft ride suspension so, I would guess they limited the top speed lower that other suspension options.

 

[vetteboy86]

H.D. Here is a link to mid america that shows a G tech meter:

http://www.madvet.com/shop?frame=1.35


As I thought more about it those runs were with the Hypertech Thermomaster chip installed. However from what I am told by people it doesn't really matter. I didnt' take the chip out and put the original back in to run it. I figure why bother. Other then that it was stock.

Since then I have done some small stuff: Vortec Ram air, air foil, 160 degree T-stat, dual exhaust, accel super coil, 8mm super stock accel wires, AC delco rapid fire plugs. These things are just mainly bonding time between me and the car. I do plan on doing it again this spring before the hot weather gets here.

Craig

 

[Vettefan87]

I ran mine with my chip and my airfoil, no Ram Air or nothing and i got around 266 or so, which I thought was pretty good. I have not ran it for 0-60. It is nice to leave it up on the window and it shows how many lateral G's you are pulling.


Justin

 

[Mad-Mic]

I ran mine with my chip and my airfoil, no Ram Air or nothing and i got around 266 or so, which I thought was pretty good. I have not ran it for 0-60. It is nice to leave it up on the window and it shows how many lateral G's you are pulling.


Justin

i hate to burst your bubbles here fella's but no way a bone STOCK even chipped 86 and 87 L98 car is producing 260+ rwhp. many dyno sheets reported over the years that i've been on this board and others proves our cars make 190-210 rwhp in bone stock configuration.

only thing a G-Tech is good for is base measurements. if it says your making 266 and you do a few mods and says your making 285 take it as that just numbers that shows that the mods work not actual figures of the RWHP output.

 

[vader86]

The L98 is accurately rated in NET power at the flywheel from the factory, and most will put down roughly 210-215 from 87-91, if they are in stock form.

Bear in mind that it also depends on type of dyno, Mustang and dynojets can read very different numbers.

Beating a 300hp mustang doesnt mean you have more HP than 300, you have to think about your torque advantage down low. I can whip a few of them in my 86. that isnt too heavily modified.

 

[ProEMTPFF]

I've searched the threads for info on the G-Tech. I know I saw a thread that had a link with the G-Tech cheap, like $30-40. Anyone know where to get one cheap??

 

[MoeJr]

I smoked a 96-98 Rustang GT with my 84 and it was bone stock. Only mod it has now is a gutted cat. converter. He was a cool guy though as he gave me the thumbs up sign when I backed off and he caught up to me.

My seat of the pants dyno tells me I am about 20 hp stronger than stock. I know what a 205 hp V8 feels like and this isn't it. This car runs too strong to be 205 hp.

:bar

 

[G Winter]

http://www.softwareandstuff.com/CES10539.html

I've searched the threads for info on the G-Tech. I know I saw a thread that had a link with the G-Tech cheap, like $30-40. Anyone know where to get one cheap??

Httpww.softwareandstuff.com/CES10539.html


there ya go. good people I buy from them now and then .