ericcer

Well I got 297.3 HP and 305.6 ft/lbs TQ with Ed Wright programming and cut airlid plus K&N (pretty average) What is interesting is comparing this graph against my LS1 car I had before. I am suprised that the LT4 HP peak is at 6000 rpm and the LS1 is at 5500 rpm. I thought it would have been the reverse. Also the LS1 graph is steeper. Maybe that is the difference I feel between the two. You arrive at max HP quicker in the LS1.

LT4 graph http://temp.corvetteforum.net/c4/eri...vettedyno1.jpg

LS1 graph http://temp.corvetteforum.net/c4/eri...yno_duals2.jpg

Ok, I fixed the links.


[Modified by ericcer, 1:49 PM 11/24/2001]

Charles Klein

I'd really like to see those graphs, but neither of the links work.

Gatorac

Here's a little help.

LT-4



LS-1





[Modified by Gatorac, 5:50 PM 11/24/2001]

ericcer

Shame on you for making me consume so much bandwidth! :)


[Modified by ericcer, 5:57 PM 11/24/2001]

NotSlo

Here is my LT4 dyno run. Very Similar.

Charles Klein

Mine is also similar. Here is the link to graph posted in the performance registry:
http://www.corvetteforum.cc/performa...ages/Dyno1.jpg

The two sets of curves are before/after Ed Wright's programming.

GS Ragtop

Here's my LT4 - very similar to yours and Doug's. Only mods on mine are Corsa and open lid (highest HP run was with air filter completely pulled).



Brad

BubbleHead

Great numbers! Looks like the LT4 is running a bit lean. Any plans for an adjustable fuel pressure regulator?

ericcer

No plan for a regulater for me. The dyno guy thought my air/fuel looked good. It is good to be a little lean for max power anyway.

Ed Ut

I forget. What is the calculation to obtain your horsepower rating based upon your rear wheel hp? Just curious since I also have an LT4. Thanks

Charles Klein

The most common, and conservative, figure is 15% loss through the drivetrain. So you divide RWHP by .85 -- that put's erricer's flywheel hp at 350. I posted a question about this recently and someone replied that Lingenfelter use 17% reduction factor. He also uses chasis dyno on the cars that he works on, so the large this factor the more fwhp he can claim to have added. For all I know he established this with tests, I just want to point out a tuner's interest in stretching the number downward.





[Modified by Charles Klein, 6:03 PM 11/26/2001]

Nathan Plemons

85% loss, wow!!! :D

Just for comparison if anybody wants it, here are my dyno's with stock LT1 vs. Hot Cam.




Looks like the LT1 and LT4 have identical stock curves, without the numbers you wouldn't be able to tell them apart. The LT4 just pulls a little harder a little longer.

Charles Klein

Thanks, Nathan. I edited my reply. I was not quite awake when I wrote that.

ericcer

Nathan. Are you saying that you got a 44 RWHP gain with the LT4 hot cam and that was the only difference?


[Modified by ericcer, 3:25 PM 11/26/2001]

BubbleHead

That's weird, when we went to the dyno this year, the shop owner recommended pumping the fuel pressure to compensate for lean conditions. I always heard you are better off running rich than lean and the shop owner confirmed that.

:confused:

Nathan Plemons

It was probably more like 30 something. I added an electric water pump at the same time, that's usually good for about 9 on the upper end.

While I was into the engine I did the cam, 1.6 roller rockers, real guideplates, hardened pushrods, valve seals, dual springs & lifters. I didn't really need the lifters, I just figured while I was into it, it wouldn't hurt, I got the comp cams pro magnum's, they are supposed to do very well in the upper RPM's.

All of this is in addition to basic tune up things like MSD coil, MSD wires, NGK plugs, etc.

To answer your question as honestly as possible, the cam and everything required to go with it probably gave me about 35, the water pump probably gave the rest.

Hutch

Just FYI, you can view several LT4 dyno results on my Hashmarks.com website at:

http://www.hashmarks.com/dyno_page.htm

There are a number of combinations here from pure stock to multiple mods. Our experience has show most bone-stock LT4's range from 295-305 RWHP.