VF1000R

I've been tinkering with this LT1 for about 9 months , and thought it was time to go to the Dyno and see what's up.

In the Impala at Atlanta , had a best of 13.9 @101 NA

Setup
3.73 Auburn posi
28" Street Tires, Drag radials ready for next year.
LT1 stock bottom end ~ 85K on it.
93 Z28 Heads , Worked, 2.02's / 1.60's , 918's , Comp gold 1.6 RR's
Clear image Tri-Y's 1 5/8 , 2.5" , Cat Delete, Borla Muffs, Sounds Good
30 Lb injectors
58 TB, CAI through a snorkel hood
EGR Delete, AIR Delete
LE Bullet Racing Roller Cam with 1.6RR's it's .565 / .570 on 109LSA
BH Tune on a 96 OBDII setup
Mallory 686, fresh OPTI, recent plug wires and plugs, 104's

At the Shop

Dynojet 224X 2wd In-Ground Chassis Dyno

Results , Air Temp 39°F

308HP, 304 TQ

He sent me the files but they are in *.drf format and i can't read them. Supposed to be sending me a PDF, unless somebody knows how to read those files.

Sniffer did show what appears to be excessively rich, like 10 to 1 at 6000

I'll post a pic as soon as I get them. However , I think the output for these mods is low. i would have expected 325 to 350.

I'm wanting to go bigger cam, and even though the springs are rated for .625 I doubt the heads are without machining (again).

Any thoughts ?

OK so the 450 below is with a 150SHOT

VF1000R

Top Run is Current, Bottom is Bone Stock a Year Ago.



Horsepower comparison Stock vs Upgrades



Air Fuel Ratio goes well below 13 ,

getsum27

ive never seen an lt1 make 232 lb ft of torque

VF1000R

Yep, heads were shot. With 85K of fairly hard miles on them the valve train was very weak.

James Montigny

iTrader: (13)

Assuming you don't have a serious leak in the exhaust, fuel pressure is normal and your ignition is working properly....

A) Have the tuner fix the tune
or
B) Find a tuner who can do a MUCH better job on your setup.

Get that done before even considering N20.
You should be making much more power, all you're doing now is washing your cyl walls down with fuel.

PCMFORLESS

at 11 to 1 it isn't washing anything down.... There is something mechanically wrong with this car for sure. It is about 100HP down at the tires, even if God came down to tune this car, leaning the air fuel up is not going to pick up a magic 100HP (15 if he was lucky)...
Also, in this case the air/fuel being rich is an effect, not a cause of the low HP. The car has fuel added for 375 to 400 RWHP in mind, due to mechanical issues it is only making 300 and therefore does not need the fuel that was added and is running on the rich side.
I have sent an email (the owner of the car emailed me and that is how I found this thread) on a few things to look for mechanically (forgot to add to check to make sure there are no dead cylinders from possibly a melted plug wire, opti problem, or bad spark plug as a dead cylinder will drag it down a ton of HP) I just had to comment on the washing the cylinder down thing and the whole kill the tuner style comment. Even a stock tune can't cause a car to lose 100HP at the tire. I'm not bashing or anything, it just always seems to be the first bandwagon everyone wants to jump on is the tune. Maybe I'm just being touchy as the holidays always get me depressed

bowtienut

iTrader: (1)

Yes. You are correct; that configuration should be closer to 350 rwhp than 309. Regarding a cam change: No, that would be huge waste at this point. Regardless of the specs on that Bullet cam, the fact that you got it from LE tells me it's capable of supporting at least a 350 rwhp setup.
It looks like there has been no attempt at a dyno tune; get that done and you will see that motor come alive.

hitmanws6

iTrader: (20)

your numbers should actually be closer to 400 with a cam that big and worked heads. something is seriously wrong. bolt on LT1s make more than that

05HD

Eh... Different dynos read different. All we can tell from this post is

1. It is running richer than optimal according to the dyno wideband (may or may not be accurate).

2. It has gained 109 whp from the previous test. (again may or may not be accurate)

3. A whole bunch of things have been changed on the car in the interim between the tests.

James Montigny

iTrader: (13)

Note the first line of my comment.

05HD

i especially don't buy this. My 1993 Z28 (also automatic) has 112,000 very hard miles on it and it still put down a lot more than the original numbers on this car.

Maybe the dyno you are using reads low? Race weight and trap speed?

Read the plugs? They look rich?

VF1000R

Weight, 4250 with a 290Lb driver
Trap Speed at 1/4 N/A about 99mph in D

if you take a look at the 200HP power curve , you can see that it's erratic above 4500, valve train was tired.

05HD

I assume that trap speed is before this round of mods. Given that assumption:

Going off of those numbers, I'd say the dyno you use reads low. Have you been to the track in the current state of tune?

94Z28rag

iTrader: (10)

You are WAY off. Something is broken or mechanically wrong with that setup.

flame

iTrader: (13)

You say worked heads by who? The motor peaked at 4500 rpm. Even a stock cam LT1 peaks higher than that. Something is causing that and it isn't the tune. Did you degree the cam? Have you asked LE what he thinks given the low peak and low tq?

DroppedM6Z

iTrader: (5)

My 95 LT1 Z28 made 303 /330 with LTs, cat back, CAI and stock tune....

i'd stay you have some bugs to work out

VF1000R

Nope , that trap speed and time is from the current mods. Have heard the same possibility about the dyno from another dyno operator in town.

unfortunately that other dyno is out of business so i can't do a comparison.

VF1000R

Local CH Shop that has prep'd many LT1's for racing.

Well, I'm not sure I follow you, TQ peaked about 4500, HP peaked at 6100.

Installed cam straight up, and did not appear to have any issues. LE has been involved with this line of questions but has not offered any possibilities , yet.

05HD

Nah, with that race weight and those mods, you are down on power. The dyno numbers seem in the ballpark. I'd start off with a compression test and go from there. Check all of the things you haven't changed since your power was low before and after mods.

VF1000R

Went back to my collection of Mag articles, and there is a build on LT1's September of 09 in CC.

They went through 4 stages.

My "setup" comes close their #4 setup , but my HP numbers follow their #3 setup. Just about 50 - 60 HP off.

It's frustrating, to think that

1. The dyno may be reading low, but
2. The engine may be out of adjustment, given the 1/4 mile trap speeds and time.

1/4 data don't lie, so by working back through the formula, the HP , seems to match the dyno.

If anyone has Quarter Jr and can plug the following in to see what they get i would appreciate it.

350 cu in. , 4200 lbs, 3.73 gears, 28" tires, AUTO, 13.99 @ 99.47, .215 RT, 2.15 60 ft.