Here's a dyno graph from my 1991 L98, Jonecap's hot cammed 1996 LT4, and a heads and cam LT1 car.



The green line is my L98. My car is a ZF6 with minor mods: 4.10 gears, dyno tune, headers, no cats, and magnaflow mufflers. I have since added 1.6 roller rockers, but they aren't reflected in this graph.

The red line is Jonecap's LT4. It's a ZF6 with minor mods: 4.10 gears, hot cam, exotic muscle headers, high flow cats, magnaflow mufflers, and a dyno tune.

The blue line is a 1995 LT1 ZF6 Corvette. It's got Lloyd Elliot heads, the cam recommended by Lloyd Elliot, long tubes, stock 3.45 gears, and a dyno tune.

The LT1 car has made over 400 RWHP in the past, and it certainly would of made more power had it been revved higher on the dyno.

 

Nice comparison!!

 

Neat! That LT4 is pretty stout.

What I find interesting is the L98 curve. Man they really fall off fast. The power curve looks more like a typical torque curve, peaking a little past 4k and then slowly curving off. The L98's A/F curve seems weird too, the leanest by far at 3,000 rpm, and the richest by 4,000 rpm.

 

That is a great mix all in one shot. Thanks. Here is my L98/TPI/Hotcam and ported Heads Dyno chart. (My upgrades are similar to the LT1 and LT4's above for a better comparison between generations)

 

I thought it was interesting how the LT4 with stock heads and LT1 with aftermarket heads had almost identical graphs up until about 6,000.

 

darned near 14.0 , WOT AFR??? wow....great results, and nice post

 

It's pretty close to 14.0 on the LT4 and the L98. The LT1 is a tad richer, but I didn't do the tune on that one. Our sniffer at the shop goes in the tailpipe, and when compared to readings taken at the header, it always reads about .5 points leaner than the A/F ratio at the header. If you add half a point to A/F graph, it should fall in line with what most people look for A/F wise. mrc24x's dyno equipment may be the same way, but I can't say for sure.

The L98 is a speed density car, so leveling out the A/F ratio was a bit tougher. It looks like there are some pretty big sways in the fuel ratio in the pic, but the way the fuel ratio graph is scaled makes it look that way. It still wiggles around some, but it probably only wobbles about .4 of a point.

 

"Our sniffer at the shop goes in the tailpipe, and when compared to readings taken at the header, it always reads about .5 points leaner than the A/F ratio at the header. If you add half a point to A/F graph, it should fall in line with what most people look for A/F wise. mrc24x's dyno equipment may be the same way, but I can't say for sure."


Yeah, it uses a tailpipe sniffer. This was with the stock chip also. I am hoping a new chip/tune and some pulleys will get me over the 330 / 400 mark.

The LT1 and LT4 dyno's look pretty close to most stock C5Zo6's. Nice.

 

surprised you did'nt throw my rag into the mix.nice comparison.

 

It almost looks like it could be the same motor up to 5,000 rpm. I guess I should be happy with the power mine is making at 84K miles with only a hotcam and exhaust as the major mods. Now we just need to install the bottle and put it on the dyno again for some really good numbers

The L98 definitely deserves the torque monster nickname!

 

Ive seen layover charts with L98/LT5, and even though it shows similar numbers down low (TQ)the L98 (especially with a little/I.E. gear) will pull away at lower speeds. After having both Ive noticed the difference. Unless you keep revs up and have gears I have a hard time keeping up with one in a tight canyon until I get some speed up.

 

Yeah...my old' '90 ZF bolt on car on a set of drag radials was a stoplight to stoplight killer. It would flat rip out of the hole...however, it ran slower 60 foot times than my LT4 car on the same Nittos...go figure.

 

An intake would really wake the top end of that L98 up and prevent that dramatic falloff. Same graph after you do an intake please. : )

 

What LE package was that? LE1, LE2?

 

I don't really know. The guy is on here, but I don't want to just be posting his dyno numbers. I'll ask the guy if he minds, and if he's cool with it I'll let you know.

I have a modified LT1 intake for my car, I just need to get some time and money freed up so I can install it.

 

I don't mind, but thanks for the consideration. I have the LE2 package.
My other graph that made over 400rwhp is in my pics on the left for comparison, but it doesn't get there until 6500.

Just for clarification, I have ported heads, but they are the stock LT1 castings. I think this shows how good the Lt4 heads are out of the box!

 

That's why I was asking. I was suprised that the LT4 was that close to the LE package. If I remember correctly LT4 stock castings flow about 240-250 at .500-.600 where as the LE2's typically flow in the 270's. Is that a Bauer cam LE1/LE2? It should be better than the hotcam also. I'm guessing your's would have made much more had the graph continued. Do you have the other mods? 58mmTB, ported intake, bigger injectors, ported MAF, etc? Do you think there's more power to be had there with some upgrades and further tunning? I wonder if the LT4 car had any porting done or other mods?

 

If the dyno operator had taken the LE-equipped LT1 to a higher rpm (6500+), you would have seen even more of a difference. You can see the LT1 graph still on the upward climb as the run ends shy of 6000rpm.

Regardless, the hot-cammed LT4 is still very impressive.

 

Yes, I have all the other mods, LE2 cam. The graph ends on my car at about 5750. I made over 400rwhp at CAM the year before in much hotter and more humid weather. I think there are some differences in the dyno setting too, I think this one has a very low humidity % setting, but that would affect the others equally. Also the LT4 is the highest HP I have seen with stock heads, especially with a Hotcam, and it is almost in the 11's in the qtr too. I believe the highest mine got to was 405rwhp at CAM, there may be a few more HP, but probably not much. I have seen some on the F body forums make 42xrwhp with my same set up, variables in dyno's, slight differences in mechanicals, I don't know. The Hotcam is known for it's great low end, and you usually sacrafice low end for top end on a cam, so I think it does very well. My cam only sacrafices a little at the low end, but more than makes up for it at the top, and the difference will grow as the graph extends. Look at my other graph, it is still making power at the top when it hits the 6800 redline(400+ from 6500-6800). I think the only way to get considerably more rwhp from an LT1 is to stroke it, which will happen when the short block dies. Heads flow 280 at .6

 

No...I've not done any porting on the car. The heads are stock, intake is untouched, stock throttle body, etc. Another forum member 96 lt-4 has a very similar setup to mine and he picked up 7rwhp by just changing to a 52mm throttle body. I may try that mod and see if that and pulleys will get me to 365.