30 replies to this topic

[rforet]

O.K. I finally got the Vette running and to the track.

Went 8.98 @ 154 with Motor & a measely 175 n20 shot. 60' was 1.28, with the wheels about a foot off the ground! 5.82 @ 124 in the 1/8. Actually, I think she can go a 1.25 60', 5.75 @ 126 in the 1/8, and 8.80 @ 156 in the 1/4. The air was bad (hot humid South Louisiana air cost me about 60 HP on my motor), and the track was only fair. I shifted @ 7000 but the n20 and the .800 lift cam spins the rpms so fast that I hit the limiter @ 8000 dropping a cylinder for a split second causing a n20 backfire. Not an "ideal" run by any means.

The new American Racing Technologies (ART) 9" with 4.11 Pro Gears worked like a charm, with 100% conversion of the HP to the rear wheels. And I thought a 90% conversion to the rear wheels is the best I could hope for. Not bad for a 3400 lb. car (3225 + me @ 175) leaving @ 2000 rpms, NO transbrake, and a small tire (MT ET Drag 15 x 11.5, stock rear wheel wells)!

If interested in a few action shots, go to www.nitroArt.com, and click on ProMod Madness on Home Page, and go to page 5...I know you'll recognize the infamous Admiral Blue and Arctic White...and oh yea, that obnoxious hood scoop.

Enjoy.

Ronnie "FoFo" Foret
Lafayette, LA.

[GS163]

Gotta love that pic with the wheels off the ground, thats killer.

[GS919]

Awesome pictures! That is one great looking drag machine!

[stgry1]

Ronnie, Great Job. Would be interested on the engine specs and the mods you've done. Those are nice times. Do you experience any body flexing with a launch like that or do you have it reinforced?

[rforet]

O.K. here goes in no certain order...$75M later;

BBC Gen VI 454 bored & stroked to 496, 11.5:1 compression (very mild) .800 lift Comp Cam (very severe) with stud girdle, Edelbrock heads capable of flowing 410 cfm (custom ported and polished), Holley HP 1250 Dominator, Eagle crank & rods, heavy duty valve springs and rocker arms (that can withstand an 8000 rpm spin), Edelbrock Super Victor intake, NOS Big Shot n20 plate on a throttle switch with a measely 175 shot, motor 45 degrees of timing, retarded 7 degrees (38 degrees) with n20, TCI TH400 race tranny with a 9" billet n20 converter (4500 stall, flashing to 5000), ART 9" rearend with Strange axles, Wilwood brakes, 35 spline axles, ProGears 4.11. 3225 lbs just car, and 3400 with driver. Motor 800 HP, with 175 n20 shot, 975 HP. 930 HP to the rear wheels. Shifting @ 6500 / 7200, crossing @ 7800. 1.28 60', 5.82 @ 124 1/8, & 8.98 @ 154 1/4. Footbraking (no transbrake). Doug Rippie coilover shocks in the front. Be Cool radiator with Evans Coolant, Meziere high flow electric water pump. MT ET Drags 15 x 11.5 (relatively small) in stock wheel wells.

Let's just say that it leaves "like it stole a TV"! At least for a 3400 lb car leaving @ 2000 rpms off of a footbrake on a small tire. All of the combos just came together to do this...engine, tranny, gears, converter, rearend, tires, tire pressure, and of course, a lil 175 shot of the "dope" to help out with bottom end torque and launch it better. I'm actually getting 100%+ crank HP to the rear wheels (after adjusting for weather conditions), and that is very rarre for a "street" (yea right!) car.

The full roll cage, a custom built tranny crossmember, and drivshaft loop, and the custom built rearend, all eliminate any body flexing, and as you know, the Vette (even the C4s) are very aerodynamic.

I hope this helps.

Ronnie FoFo Foret
Lafayette, LA.

[stgry1]

Motor 800 HP, with 175 n20 shot, 975 HP.  930 HP to the rear wheels. 
I'm actually getting 100%+ crank HP to the rear wheels (after adjusting for weather conditions), and that is very rarre for a "street" (yea right!) car.

Very impressive list of mods. You sure have a well thought out setup on that rig. I'm not surprised you're achieiving the numbers that you are. I am confused on your statements of 100% HP at the rear wheels tho. Parasitic loss is a factor of life regardless.You can minimize losses but you state 100% + I'm missing how you are not suffering from any driveline loss at all....help me out here

[XGS891]

Holy cow, those are some serious times. I've been over 150 a few times in various vehicles, but it took a lot farther than 1/4 mile to get there. That's an awesome setup. Keep us updated on your times, and get us some video of one of those runs. It would be awesome to see.

I've gotta side with Chris on the how are you not suffering any driveline loss at all? I'm sorry, but my engineering background leaves me a little sceptical sometimes. If you've found the formula for perpetual motion, then you need to let us know about it.

[rforet]

Thanks for the comment on the parasitic driveline loss. You are correct. It is near impossible to get 100% conversion of crank HP to the rear wheels.

So, what gives?

Fact: @ 3400 lbs @ 154 mph = 950 RWHP;
Fact: Engine dynoed @ 758 HP "motor";
Fact: Sprayed 175 n20 shot;
Fact: Weather conditions cost about 58 HP (temp, humidity, barometric pressure);

So, theoretically, 758-58+175 = 875. 950/875 = 109% conversion.

Well, these are the explanations;

1. ZERO loss due to "air", as n20 makes its own air (O.K., that accounts for 58 HP);
2. Spraying 175 n20 on my set-up (low compression motor, tight converter, huge heads, big camshaft) are all the perfect combo for the n20. In truth, the "lil" 175 shot likely produced a steroid-like effect closer to 275 foot lbs of Torque and 250 HP (O.K., that accounts for another 75 HP);
3. I changed to Royal Purple Race 41 Synthetic Oil (O.K., that accounts for 10 HP);

So, 758 (dyno HP) + 250 (n20 HP) + 10 (Royal Purple 10 HP) = 1018 crank HP.

Therefore, 950/1018 = 93.32% conversion of TRUE crank HP to the rear wheels. With all of the racing parts I have (TCI tranny & converter, custom tranny crossmember, Jerry Bickle Race Cars chromolly driveshaft, custom ART rearend, Strange 35 spline axles, etc.), and the relatively stiff chassis, 93% conversion to the rear wheels sounds just about right.

I hope this long explanation helps. My racing buddies and I had a long discussion on this topic when they saw my mph. It does defy physics at first blush.

Ronnie FoFo Foret
'96 Vette GS Clone
Lafayette, LA.

[GS163]

[AMUZZY]

I'm glad you guys know what that means 'cause I sure don't

[rforet]

Andy, I didn't know if your comment was meant to be a question or what. Let me know if there is a response you want from me. Sorry for the length of the previous post.

FoFo

[GS163]

I think what he was saying, is that he was just as confused as I was after reading that post. I have reread it a couple times since and it is as clear as mud to me now.

[stgry1]

OK Ronnie here we go....I'm having a little confusion on getting the numbers straight first so correct me if I'm wrong. You posted

Motor 800 HP, with 175 n20 shot, 975 HP. 930 HP to the rear wheels

on your orig post. Now considering that MOST, if not all N2O manufacturers rate their kits at RWHP; I’m calculating 704 RWHP motor (I’m factoring ONLY 12% loss for your setup) + 175 spray = 879RWHP. Am I on track so far?? Now we take your last post stating

Fact: @ 3400 lbs @ 154 mph = 950 RWHP;
Fact: Engine dynoed @ 758 HP "motor";
Fact: Sprayed 175 n20 shot;
Fact: Weather conditions cost about 58 HP (temp, humidity, barometric pressure);

Take you FACT RWHP of 950 would equal approx 9.47ET depending on traction of course. You stated 8.94ET. We have approx .5 diff which in this time range is HUGE but achievable. Based on my HP calculations of 879RW..I’m looking at an ET of 9.72. Now were getting close to a full second difference btwn times. You also factored in heat and humidity at your elevation which is smart to do. But consider this…your using an air altering chemical mixture – N2O. I don’t think you would see 58HP loss when spraying (on motor yes). Because at this point you’re cooling and densening the air as it makes its way into the intake.

I agree with you on the 930 at the wheels to be able to achieve your ETs but I'm having trouble figuring out how you're getting there.


True, a motor set up for NOS will definately benefit from it but 75 HP worth
and a 10 HP gain from synthetic oil?? Man, thats a selling point!!

I'm not trying to argue with you here...just trying to comprehend. I can see with your setup, minimizing rear wheel loss but I can't see these other factors making up the difference in HP gains (in this case 'lack of HP loss').

Have you gotten a dyno run with the motor and spray?? That might help clear things up a bit.

[AMUZZY]

Ronnie, like JP I don't really understand the technical aspects of what your car can do. All I know is that it sounds like it is fast.
Sorry for the confusion

[rforet]

Hey guys, great posts. It is hard to explain the results we're seeing at the rear wheels, but the simplest way to determine RWHP is by the MPH, which, IMHO is more accurate than ET, as the latter is more affected by track conditions, traction, gearing, tire size, etc. MPH is pure HP.

3400 lbs going 154 mph = 950 RWHP, straight from the Moroso power guide that measures such things.

How did we get there is a function of all the factors I mentioned in the previous posts, plus one more key element that I forgot to mention...custom built 2.25" open headers. We figured from the dyno results that this added about 50 HP vs. the previous Hedman Tight Tube Headers. Again, this is on a motor producing almost 800 HP, so this is a gain of about 7%. Not bad for about $1,250.

Basically, 758 dyno-proven "Motor" HP + a 175 n20 shot equals 933 HP at the crank, with no air or other HP adjustments. Assume "no air" adjustment, as the n20 makes its own atmosphere. That saved about 58 HP on the day I ran. Assume a gain of about 10 HP due to the Royal Purple Race 41 synthetic oil ($100). Now assume a gain of about 20 HP "post dyno" due to a larger Holley 1250 Dominator ($1,000) vs. a smaller 1150. Finally, assume the 175 n2o shot produced exactly 175 RWHP, as advertised. That gets us to about 963 HP at the crank (758+10+20+175). That would equate to a RWHP loss of 1.35%, or a RWHP conversion of 98.7%. Even with all the fine chassis pieces I have (and the headers), that seems unlikely. So, what gives?

The answer is in the effect of the n20 in producing tremendous low end torque, and the multiplier effect the TCI torque converter is experiencing. Most likely, due to my set-up, but particularly the "tight" converter, the 175 n20 shot is really producing about 250-275 HP (and likely 300 lb. ft. of Torque). Due to the big lift on the solid camshaft (.800), the n20 is really needed on the low end to launch the car. Note the motor pass reflects a 60' of about 1.55 (10.15 @ 136) vs. a 175 n20 pass 60' foot of 1.35 (best 1.28), a huge difference.

The conclusion is that about 1038-1050 HP is being produced at the motor (758+10+20+250). Based on 950 RWHP, this converts to a RWHP rate of 92%. This is more likely, and exactly what I expected (our goal was a conservatinve 90% to the rear wheels).

The engine has been dynoed several times under different configurations. The Larry Meaux dyno used is very very conservative, but accurate (other area dynos would likely show HP of 825 vs. 758). We call 'em "ego dynos" around here. The bottomline is what is the MPH for the vehicles weight? That is the true RWHP.

I wasted about $250 one time on a chassis dyno while spraying n20, when I was making less power. The dyno never would register an accurate # due to tire spin caused by the excessive torque of the n20.

BTW, we added some new goodies this week, and are anxious to see the new results once some tnt is done. A TCI transbrake was added, as well as an MSD RPM window switch. The former will allow us to leave at an RPM closer to the converter stall speed (4500-5000), and hopefully still have traction. Relative to leaving off idle @ 2000 RPMs, this should help the 60' & ET...IF we get traction. We feel a 3000 RPM chip is the maximum the tires can take w/o losing traction. The window switch will set the n20 "on" @ 4000 RPMs (after the transbrake is released @ 3000 RPMs), and will shut the n20 "off" @ 7800, just before hitting the rev limiter @ 8000 (to avoid the dreaded n20 backfire).

I'll keep all posted.

P.S. People just rave about that Admiral Blue paint color, with those wild Arctic White stripes! And, of course, I get asked ALL THE TIME why I forgot to put the Red hash stripes on the right side! Go figure.

Ronnie "FoFo" Foret
Lafayette, La
'96 Corvette Grand Sport "Clone" (actually titled as a 1984)

[rforet]

Continuing this discussion of RWHP, here's some updated data on my Vette to mull over, from this weekend. The Vette ran 139 seven times over the last two days, so it was not a fluke. The passes were all "motor" only, no n20 to distort the results (i.e. discussed possiblilty that more HP is being produced than the advertised n20 pill rating of 175).

3400 lbs., 139 mph, temp 100 degrees, humid as h*** (south Louisiana), track temp hit 140. Let's assume a conservative LOSS of 70 HP on the motor (dynoed @ 758).

139 MPH @ 3400 lbs indicates 680 RWHP.

Hmmm, 758 less 70 HP Loss due to weather in 688 crank HP.

680 RWHP divided by 688 crank HP = 98.8% conversion to the rear wheels.
Seems like nothing but math to me.

By the way, NHRA Pro Stock cars (ala Greg Anderson) produce well over 100% conversion to the rear wheels. Again, just do the math and figure how much RWHP it takes to run 204 mph in a Pro Stock car.

FoFo.

[rforet]

Update 7/6/05: Ran the Vette a week or so ago, and in the worst of the south Louisiana summer humidity, the Vette ran a consistent "motor" MPH @ 139 over and over...the best yet. The engine is really strong, and consistent. I went to the Finals in the Footbrake Bracket Class BOTH Saturday and Sunday. Lost Saturday due to the Battery running down, causing the MSD to fail. Lost Sunday on a (.016) redlight...damn, that was close to real good! Best "motor" ET was 10.21 due to converter being too tight and not enough gear (4.11), and leaving off idle @ 2000 rpms (weak 1.55 60'). It really is hard to have it both ways...a "motor" car and a "N20" car. The specs (especially tranny converter and gearing) are built for n20.

Made one n20 pass, however, the n20 bottle had more air than n20 for some reason...still went 150 MPH with a dismal 1.45 60'.

New mods: New high torque Powermaster Starter, so the Battery won't get so run down from starting over and over (despite using a charger after every pass), new Tach capable of playing back every detail up to 80 seconds of each pass (including the burnout, and all shift points). Also, refilled all 3 n20 bottles with fresh n20.

Hope to run next Wednesday night, and wanting to get in the 8.8's @ 155 with a 1.27 or better 60'...the transbrake and 3000 rpm chip should help vs. leaving at idle of 2000 rpms.

Engine internals all look real clean with springs, rockers, oil...all looking perfect, with no fluid leaks whatsoever. All bolts snugged up, and ready to rumble...

Ronnie "FoFo" Foret
Lafayette, LA
1996 Grand Sport "Clone" (titled as 1984)

[HUTCH]

In a word... AWESOME! You do us all proud, FoFo!

[rforet]

Ran the Vette again tonight to complete my License passes.

N20 Pass # 1 spraying just 175: Missed and stumbled due to n20 purge not working and bottle pressure too low at 890 psi, 60' a dismal 1.675, sprinted from there to a 9.287 @ 156 mph. The mph was my best yet. The air is terrible in Louisiana this time of year, even if the n20 makes its own atmosphere.

N20 Pass #2 spraying the same 175: Better, but still stumbled due to purge not working, low bottle pressure. 1.39 60' 5.79 @ 124 1/8, and 8.94 @ 155 mph 1/4. Best ET to date.

Gotta believe the Vette has a 8.75 @ 160 in her in some good air in the Fall.

What a rush!

Ronnie "FoFo" Foret
1996 Corvette GS "Clone"
Lafayette, LA.
496 c.i., 780 naturally aspirated HP, about 1000-1100 with 175 n20 shot (990 RWHP @ 3400 lbs)

[84 GRANDSPORT]

That thing is fast!