PontiacBonnevilleClub.com

radomirthegreat wrote:I'm a wuss. Only 111mph according to the HUD.

I wish I could tell how fast for sure I was going.... over 100 but thats as high as the speedo goes on the '89. Only 85 on the '88 :(

147 on a closed track

it got a lil shaky so i let off :sad5:

deffenatly could've gone for more tho,
it was only at 4k in 4th gear when i let off

Same as Bill at 156 mph. Yes it got a bit floaty.......really needs to be lowered an inch or two to help with high speed aerodynamics.
The fastest I've seen posted is Shadd when he took his 00 SSEi to 162 mph on a deserted country highway.

Keep in mind, I've made runs to various speeds (I have a favorite old deserted highway in Eastern Oregon that is no longer used, which has a 10-mile long flat stretch).

I make slow passes to inspect the road before I make my run and to scare off any critters from the edge of the road. Even a rabbit at 150 can do great damage.

I've made several changes to the car over the years to improve the high speed handling, and it's far better now than it was when I hit my 156. Tire sidewall strength is a huge issue. In general, having the proper rating will fix this. Unrated or older tires will actually increase in diameter as the sidewall stretches from centrifugal force, lifting the front of the car and causing it to 'float'. This over-sensitizes the steering.

When I did my new rear struts, I deliberately adjusted the ELC before my alignment to ride 3/8" to 1/2" higher in the rear (not really noticable sitting there) to hold the nose down. Further improvements to my suspension, and far better tires (ZR rated) have improved it to the point that I have beautiful handling up to 150mph now, and probably well beyond.

Simply changing my tires from the originals (Dunlop D60 H-rated) improved stability by about 10mph. What I mean by that is that the car on the dunlops would start to become light on the front at about 125mph with the Dunlops. When I got my first set of Toyo Proxes TPT's, that instability 'moved up' to about 135-140mph with the tire change alone. Further improvements through the years and FAR better tires (Toyo T1R's) have pretty much pinned the car down to any speed I care to take it to.

I've tempted fate and danced with the devil. I know where the devil lives, and while I know the car now has more in it, I'm not concerned about it enough to feel the need to see where it is. 150 is plenty.

Just remember, each 10mph faster you go takes more and more hp to achieve, as you 'hit the wall' between aero drag/frontal area, and enough horsepower to push through it.

The drag coeffiecient of a 92-99 Bonneville (no distinction made between the different front bumpers) is .360, and the frontal area is 24.3 Sq/Ft. At 140mph, aero drag is costing me 160hp. This doesn't seem bad, but I'm assuming that's costing me 160 wheel horesepower, which is about 200 crank hp.

You have to remember to calculate 20-25% loss from the crank to the wheels through the trans (25% typical, 20% possible on performance/race built fresh transmissions). Assuming the 25%, here are some examples of what it takes:

Drag Coefficient (CD) 0.360
Frontal Area (sq. ft.) 24.3
Weight (for all comparisons) 3800 lbs

Vary speeds......

100mph requires 70hp at the wheels, or 87.5hp crank.
110 mph requires 91hp at the wheels, or 114hp crank. (26.5hp more than 100mph)
120 mph requires 116hp at the wheels, or 145hp crank. (31hp more than 110mph)
130 mph requires 145hp at the wheels, or 181hp crank. (36 more)
140 mph requires 180hp at the wheels, or 225hp crank. +44
150 mph requires 219hp at the wheels, or 274hp crank. +49
160 mph requires 264hp at the wheels, or 330hp crank. +56
170 mph requires 314hp at the wheels, or 393hp crank. +63
180 mph requires 371hp at the wheels, or 464hp crank. +71
190 mph requires 435hp at the wheels, or 544hp crank. +80
200 mph requires 506hp at the wheels, or 633hp crank. +89

See how each 10mph increase requires more hp than the 10mph increase before it?

Look up the Spirit of Bonneville and you'll now see why they built it for 600hp to achieve their 200mph record in a FWD Bonneville on the Salt Flats. Keep in mind these numbers are close, but don't take into account temperature, humidity, barometric pressure, frontal lift, drag from the tires, or other small factors. But it's a good comparison to see how the aero drag takes more and more work to overcome as speed increases.

Intense's goal of hitting +200 mph with the new twin turbo'd G8 should be achieveable.
My guess is that they will get about 700 hp out of it.

willwren wrote:My HUD is within 1mph of my GPS over 140.

Yes, aero drag plays a huge factor the faster you go. Weight of the car and hp/tq/gearing mean less and less the faster you go, and it's a logarithmic function.

i thought GPSs were notorious for being off for mph?
i know for a fact you can't used them to fight speeding tickets because of their inaccuracy...

also your trannies gearing wouldn't let you ever hit 200mph...Spirit of Bonneville hit it with modified gears right? that tranny they used wouldn't be very useful in a 1/4 mile or on the street...

My theoretical top speed at 6000 rpm in 4th gear is 205 mph.

Paul's post above is based on GEARING, but doesn't take into account aero drag, or all the other smaller factors. Paul's car in actuality is in the 160/170mph range.

GonneVille wrote:then at 110, it felt like the car "settled" on the shocks and just sucked down on the road....

Mine felt exactly the same at 112 MPH...4AM on E-way...no traffic...it felt like it had alot more to give.

Slowed down to 95 ( in a 55) and a cop pulled me over 5 miles down the road...only got a warning...

Yeah, I've seen 110 before passing a line of cars. It got there so quick, I had to let off before I passed them all.

I've hit 160 late at night on an empty road. That was quick enough for me and the car proved it could've hit its mid 170ish gear limited top speed. Those speeds ruined my front air dam (nearly ripped it off and buckled it in the middle) which would have been a disaster at the time...never doing an absolute top speed run in this car again.

My GPS has gotten me at 124 on a couple mile long straight middle-of-nowhere road. My tires are only H rated (130 MPH), so I would never think about going any faster than that. It was still gaining speed when I let off... but I'm not sure if I could hit 130 MPH... nor would I want to try.

And for the record, I don't typically go faster than 80. If I want to go FAST, I hit 105 and slow back down. I just don't trust how many different things could go wrong on an 11 year old car. Given it is maintained and inspected... but you never know.

EDIT: This is an SLE, not a boosted or 2 extra cylinder car lol. Should have read thoroughly... perhaps I'll start my own thread lol.

i hit the limiter in my '88 (108? i dunno, my speedo only went to 85) but i backed off quickly as i was afraid the doors were about to fall off (literally)

2000Silverbullet wrote:Same as Bill at 156 mph. Yes it got a bit floaty.......really needs to be lowered an inch or two to help with high speed aerodynamics.
The fastest I've seen posted is Shadd when he took his 00 SSEi to 162 mph on a deserted country highway.

And not something I'd recommend trying again. I tried some runs in O/D, but was afraid of the tranny comin' apart, so that was maxed out in 3rd at somewhere north of 6 grand. Someday I'll have an SSEi again, and I want to hit 170, this time down at Bonneville.

I had the front end of my car up on jack stands, ran it through the gears with the wheels in the air, I know the HUD tops out at 199 MPH. I was a little afraid of my tires comin' apart, but they held.

DaBlackPearl wrote:My best is 125mph both on HUD and Garmin Nuvi GPS.
I don't feel the car is stable at all over 105mph.
This is probably the tires.
The other thing is once I get over 85 the car really falls flat on climbing into the 100's.
This may be because the Boost solenoid is turned all the way down to give the boost sooner. This may be affecting top end.
Without question though, my car runs out of A$$ at around 120mph and is much stronger in the 0-90 zone.

This is all kind of odd to me. My 95 with just a pulley and FWI pulled hard all the way up to 128, when it ran into the brick-wall speed limiter.
It also felt steady at all times, only getting a little light between 95 and 110, then settling down rock solid up to 128.


Also, I've run a 92-95 SE up over a hundred, and it will never happen again. I didn't stay there long, as the car was so floaty that it had no feel at all in the steering. All in all, a bad experience, and one I WON'T be repeating...the splitter on the SSE/i makes a HUGE difference in behavior...

With my 97, i hit 140mph once, and that was it.
Enough to scare me.
my hud hit 199km/h then started reading 00,01,02, and so on...pretty neat, it also flashes, and the check gauges light comes on lol

2000Silverbullet wrote:Same as Bill at 156 mph. Yes it got a bit floaty.......really needs to be lowered an inch or two to help with high speed aerodynamics.
The fastest I've seen posted is Shadd when he took his 00 SSEi to 162 mph on a deserted country highway.

Bummer -I got him beat by 1 mph according to my HUD in my current SSEi.
My old 1995 SLE SC could have gone higher than the 129 or 130 mph I topped it out at, but like has been mentioned previously -aerodinamics really are a big factor. The SLE SC was starting to feel unstable over 125 so instead of seeing what it was capable of I just decided to out do a stock pcm SSEi as my SLE's original e-prom was governing the car at 105.
My SSEi felt stable pretty much all along up to 15x and when I let off at 163 I was getting a little bit uneasy, but not like in the SLE at 129-130.

There's a big difference in stability due to FE1 or FE2 suspension, and SE/SLE body as opposed to SSE/SSEi body. While both of my cars have FE2, the SLE doesn't have the good front end to apply front downforce at high speeds. It's obvious.

128 in my old 95 SSEi and I don't remember how fast I had the SLE up to....Maybe 115?