Dyno Baby!!!

[mholhut]

To make a long day and story short, here are the lessons learned:

1. The exhaust dump on my car netted a gain of 10 HP over the normal setup.
2. My nitrous setup netted an SAE Corrected HP of 240.23 to the front wheels (5 below last year)
3. The difference between my old 96 motor and the new 97 motor is 11 HP at the wheels. (new motor is more powerful)
4. 182.64 HP - normal exhaust, no nitrous / 240 HP.23 HP - open exhaust, with nitrous = gain of 57.59 HP from the nitrous and open exhaust.
5. The car is running dangerously lean with the nitrous.

All HP numbers are SAE corrected, and yes, I have the graphs to back them up. Email me for the graphs.

 

[SCOTTDW]

I was wondering about the loss of torque using the dump. Are you racing the car yet using the dump? Also Mike, are the only other exhaust mods the performance muffs and third cat removal?

Scott
98SF
K&N Panel
Magnaflows 3"tips
BFGoodrich KDWS

 

[SHODWN]

removing the third cat and res is the only way to go. as many of us can show proof. anyone that says otherwise should not speak at all.

 

[mholhut]

I agree with Kirk 110% and would add that a less restrictive exhaust is beneficial for top end HP. On the Gen III SHO, this will hurt low end TQ as a result though, but only below 3400 rmp's. When you think about it, how long are you below 3400 rpm's at WOT.... not very long.
My dyno comparison between the modified exhaust and the exhaust dump shows a gain in HP across the board. From 48 mph, there is a 5 HP gain with the dump, and the HP gain from it peaks at about 115 mph with a 10.11 hp increase.

Scott, to help answer your question about racing, it all depends on what kind of racing you're referring to. I've dragged the car with the open exhaust and netted a best time of 14.3 (with nitrous). That was on the old '96 motor in rather hot and humid conditions. If you are interested in dragging with a dump, I'd say there's a benefit (nitrous or not) because at least on my car, there's a gain in HP from 48 mph (where the chart begins) up to 100 mph (where most of us have finished by.) I've autocrossed with the dump as well and have also found it beneficial "because of" the TQ loss. Again the old adage in autocross: "slow down to go faster." I have not had the dump open on a road course however, so I can not comment in that respect.

There was alot of speculation and hearsay about open exhausts loosing power, but I hope that I've put most of that to rest. Any concerns with loss of low end TQ should be compensated with by other mods, like a UDP('s). Best way to get data is to get the car on a dyno.

 

[stephen newberg]

"anyone that says otherwise should not speak at all."

Kirk, do you intentionally phrase your statements from an Olympian viewpoint? Would you speak like that to someone in person?

pax, smn

 

[SCOTTDW]

Thanks for the input Mike. Very good information. I was pretty much asking about the quarter mile performance. Sounds like the way to go.

Scott
98SF
K&N Panel
Magnaflows 3"tips
BFGoodrich KDWS

 

[Mac98SHO]

Mike,

What jet did you have installed?

 

[mholhut]

stephen newberg:
Would you speak like that to someone in person?

No, Stephen, he's much worse in person wink

SCOTTDW:
Thanks for the input Mike. Very good information. I was pretty much asking about the quarter mile performance. Sounds like the way to go.

No problem Scott. Without nitrous, I'd definitely try to have as many power adders to compensate for the loss of low end TQ. At least you wouldn't have to worry about the tire's hooking up on a launch.

Mac98SHO:
Mike,

What jet did you have installed?

The wrong one. wink

I was running a 41 nitrous and a 28 fuel. I might drop it down to a 26 or 25 fuel to try and richen the A/F ratio, but I have to do so without running too rich off the bottle. My A/F curve was excellent when I wasn't running the nitrous, but with my nitrous runs, it leaned the fuel way out.

 

[tomw]

Forget the dyno numbers-you have not lived until you hear Mike Holhuts car with the cut out open. The Gen3 V8 with open pipes is music to my ears!

Tom W

 

[SHODWN]

Its tuff being upon Mt.Olympus.. But sure I would tell you you or anyone in person the same. You may laugh becuse of the way I say it, reading email or Messages on the board can be taken as combative or abbrassive. Its not"Always" my intention to sound like that but then again I cant tell you how to interpuret my writings.

The only thing I can say is I do the stuff that people say wont work and make it work and show proof. The stuff that people say dont work mostly comes from 1 or 2 people that tried stuff on the V8 SHO back in 96, and since then everything that has been said not to work or cause problems is false. even the TQ that you lose supposedly I disagree with. I should have the least amount of TQ according to what has been said bit yesterdays run of 206.9hp and 238.0 ft tq show differently. along with my 15.1 with 2.0 60' times. still waiting to get a higher set of numbers then turning to NOS to finish.

as of today Mikes N02 setup would send me to 264hp, so I need to squeez 11 more HP then I will add nos. I would like 275 to the ground before I sell this car.

and just as a side note, on 11/3 I had 177 to the ground the CHIP and a little polishing of the intake has put me at 205 for 75% of my runs in the last 15 days.

 

[mholhut]

tomw:
Forget the dyno numbers-you have not lived until you hear Mike Holhuts car with the cut out open. The Gen3 V8 with open pipes is music to my ears!

Tom W

Booohahahahahahahahahaha!!!!! Glad you liked it Tom wink

 

[mholhut]

SHODWN:
(snip)...and just as a side note, on 11/3 I had 177 to the ground the CHIP and a little polishing of the intake has put me at 205 for 75% of my runs in the last 15 days.

You forgot that you probably had some help from the UDP as well. I'm accounting that as the difference between your car -vs- my car without nitrous. Gotta see what money I have hidden away to get me one or a set of them wink . . . and figure out why the car is running lean.

 

[stephen newberg]

I will admit I am looking forward to this new chip, Kirk. Do keep me (and everyone else, obviously) informed as to progress on it.

pax, smn

 

[SHODWN]

You think what is the difference? The UDP? thats been on the car for 1.5 yrs, and if you ask me it did zero for me. Most guys say they pick up a tenth or to- I never did. Now I have the other 2 to put on in addition to the crank pully, well see if that made a difference.

Mike my Sept Dyno stock was 177
with the chip it got me into the 190's
now I ported and polished the intake, and im ave around 205. but now since I did that work to the intake im still in the 200 range without the chip. We will do up your spare to double check.

 

[stephen newberg]

Kirk, you have me confused at this point. So initially it looked like the chip was good for 20ish hp on the ground and the port & polish job was good for another 15. But with the chip removed, you are still at 30 hp up on the ground, so the port and polish is providing that now and the chip was providing only 5 hp after the port & polish job? If I have that right, it sounds like the way to go is the port & polish job onthe intake rather than with the chip. Or did I misunderstand something there?

pax, smn

 

[mholhut]

Without knowing what the chip is improving, I'd have to say you are correct with your analysis, Stephen.

Kirk and I will be porting/polishing my other intake to see if the same difference can be noted on my car without a chip. I'm also thinking of eliminating the tuned runners in the surge tank to see if any increase in HP or TQ can be noted on the top end. Man, it's real nice having a spare of everything so you can test this stuff out. I just wish dyno time wasn't so expensive.

 

[stephen newberg]

Thanks Mike. I am very much looking forward to what you and Kirk find out. Are you doing the porting and polishing yourself, or sending it to a shop to be done? If the latter, what kind of cost are we talking about?

pax, smn

PS: Hey Kirk, how about buying these spare tires so I can afford to do some of this?

 

[SHODWN]

how about if it works on his spare motor, I do i for you in trade for the tires