Bonneville World of Speed MotoIQ Project 240sx spin at 193mph

Bonneville World Of Speed Part II:  200 MPH or Bust!

By Chuck Johnson
Photos by Joe Lu


Bonneville World of Speed MotoIQ Project 240sx spin at 193mph

In our last update, we left off having just set a new Bonneville H/PS land speed record at 184.1 MPH.  (Click here to read about part one of our Bonneville World of Speed adventure) On the second of the two record passes, Project 240SX LSR and its 600 plus horsepower 1.5 L engine, had recorded a fastest speed of 191.9 MPH.  With more than enough power on tap, our goal of pushing the record to over 200 MPH seemed well within reach.


At the staring line at the 2014 Bonneville Salt Flats World of Speed

Since we had pushed the record to over 175 MPH, Project 240SX LSR was now qualified to run on the “long course.”  This meant we had several more miles to work with to achieve our 200 MPH goal.  Before the next pass though, we dialed more toe in into the rear suspension in attempts to tame Project 240SX LSR’s tail happy attitude.

With more toe in dialed into the rear suspension, we headed off to the starting line.  Check out the video below. 

While you’re checking out the video, keep an eye on the mountains in the horizon and use them as a frame of reference.  In doing so, you’ll begin to understand just how much of a handful a high horsepower rear wheel drive car is on moist, traction-less salt.  
Bonneville Salt FLats World of Speed MotoIQ Project 240sx spin at 193mphIf you watched the video carefully, you may have noticed the digital GPS speedometer reading 193 MPH right before the spin.

Just a month before World of Speed, Bonneville was completely covered in water resulting in the cancelation of Speed Week.  Although no longer covered in water, the salt was still super moist and in all around terrible condition.  This made accelerating more of a fine ballet requiring a combination of precise footwork and delicate steering wheel inputs.  Was the poor traction what caused the spin at 193 MPH though?

Bonneville Salt Flats World of Speed MotoIQ Project 240sx time slip

Although we spun the car, we still managed to cross the last set of lights at 184.1 MPH.  If that speed sounds familiar, it’s because it matches the record we just set earlier in the day.  So the question is, did we qualify for a new record?  
Page 1 of 4 Next Page
Bookmark and Share
Wednesday, August 05, 2015 1:37 AM
Obviously, that hood buckling is a huge deal. Is there any way to alleviate that pressure with some vents or panel installation or removal?
Wednesday, August 05, 2015 2:29 AM
That really is both impressive and frustrating.

I would not base anything on slow speed wind tunnels though.

The S13 chassis is known to have lift problems. the rear end feel light, but that is because the front end goes high first, lifting the whole car.

The hood buckle clearly shows there is a huge pressure building up at the front of the car, which then proceeds to lift the whole car. With the car's suspension a ttheir maximum travel, you now have a very open rear end, and the car spins.

i'd say there are 2 approaches there, the first one is reducing front lift.
If it is allowed by the rules, mounting the fenders the further toward the exterior you can will help a lot. The fenders gap at the door junctions will relieve underhood pressure (there are holes used to let cables go around, which air can take to evacuate), and the gaps between hood and fender will do the same. I discovered this to be a great help to manage temps, but i am not going that fast. The cost of this will be drag, of course.
I use that for heat management, my s13 lost 10°C on oil and water temps on track.

You could also close the front opening a bit, if you don't have heat problems. Finally, without going full type X, you could use a mk1 front bumper lip, which is bigger and go lower.

the second approach would be to tune the suspension so it behaves better when nearly fully extended. This would make it harder to drive until the car actually starts to lift, as there will be more toe change front and rear on every bump, but it would reduce toe change at higher speed.

If the car is driving on bump stops at nearly 200mph, it might be difficult to control too... Would you benefit from lifting the car a bit, to try and get more suspension travel ? Or use softer, longer bump stops so they actually work as a damper when the car is lifting ?

Wednesday, August 05, 2015 5:27 AM
@Crousti, I don't think altering the fenders would be allowed in Chuck's class. What about venting the hood and/or sealing the engine bay floor? I know the USCTA rules are pretty strict, so that may not be possible. How about the old JDM back of the hood lift? Just space the hood on its hinges a centimeter or two and that will relieve the pressure very nicely (which I think was the original point of spacing the hood on the home built JDM racers). Getting some of that underbody air going over the car will definitely help keep it on the ground. Any chance of venting the rear bumper too? Or sealing it off to keep air from curling under it?
Wednesday, August 05, 2015 6:36 AM
Can you seal up the underbody some? Specifically a good undertray under the front. The Zenki front bumper with a lip is much better shaped for a high speed run, since it has a much deeper airdam shape. It's probably superior to the Type X stock bumper (which has more opening area, but I don't think you need that). Also, you can probably close up a lot of your front bumper area if that's allowed.

I would try the stock S13 urethane rear spoiler. The Type X wing will probably make a small amount more downforce, at the expense of a lot more drag.
Wednesday, August 05, 2015 9:24 AM
8695: How well does shimming the hood really work? I tried about 1/2-3/4" spacers on my Mitsubishi Starion and found that cowl pressure was high enough to blow a piece of masking tape I folded on the rear edge of the hood into the engine bay. This was at speeds over 40-50 mph.

Granted, in my case I've got an intercooler blocking the majority of the radiator inlet which I know is restricting a fair bit of airflow into the engine bay based on some cooling problems I have. My engine bay pressure may be lower than normal.
Wednesday, August 05, 2015 9:33 AM
@8695Beaters actually no altering is involved. it is just about using OEM front fender builtin clearance to set a bigger gap between them and the chassis. Simple case of loosening fender to chassis fasteners, pull the fenders outwards, then tightening it again. it will not create a massive opening but 2-3 mm opening on both sides of the hood and near the doors will help relieve the pressure. This can be done without modifying the panels.

From memory, the oem urethane spoiler makes the scx better by 0.01.

i think the spinning problem is caused by huge toe change rate once the car is lifted on its suspension... time to play with traction arm length.
Wednesday, August 05, 2015 9:36 AM
Lifting the hood out back doesn't let air out because it's a high pressure area at the base of the windshield which is why that masking tape blew in and not out. I like Crousti's approach, I haven't heard any of that mentioned in the buildup so there may be some merit. Lowering the front lets less air under the car in the first place so may help out some. It's why the C5 Corvettes (and others) run a rake and the rake is factory specified when setting the ride height.
Dusty Duster
Dusty Dusterlink
Wednesday, August 05, 2015 11:45 AM
Can you get a hood somewhat like this to put on the 240'?


Would that be class-legal?
1nvisib1e Sadd1e
1nvisib1e Sadd1elink
Saturday, August 08, 2015 3:05 AM
Are you looking for the old oem style spoiler such as this

I have the other version of this similar oem spoiler that has the rear stanchions allowing the spoiler to be bolted from the top and the rear of the hatch.

Are you able to use helicopter tape along the edges of the hood and fenders??

Does SCTA allow the use of rear underbody channeling of air. Not necessarily constructing something elaborate like in time attack. More or less something to close up the rear fenders, bumper, and suspension components from adding to the turbulent air at the back of the car.

Looking at the wind tunnel video and comparing the silhouette of the FC, having a rear element wing that trails 2-3 inches further back of the hatch could help in high speed stability. It might also encourage in generating a vortice of air underneath the wing and directly behind the bumper.
Post Comment Login or register to post a comment.

MotoIQ Proudly Presents Our Partners:

© 2018 MotoIQ.com