Texas mile

[WestTexasS2K]

I thought I would type up a quite note of what 7evin did at the Texas Mile event. He posted it under the Ultralite under construction, but most folks who dont care about the Ultralite might not have looked in there.

 

We went down to Goliad Texas to run the Texas Mile on Oct 23 & 24. This event is a standing mile so its like a drag strip run that doesnt end for a mile. We went with the goal of doing 180 mph which is pretty fast in a LSIS type vehicle.

 

7evin is running his new engine and from the previous dyno session we were only able to get 338 rwhp out of the car. We just were not able to build the boost we wanted. So a call was made to Rotrex and they sent us a prototype unit that isnt on the market yet. It is their newest baddest unit they make. It is several sizes larger than the unit we were running. 7evin was a week away from having to go Texas when we found this problem out so we were agianst the wall in getting the new supercharger. It came down to the wire. If it had been anyone other than 7evin and his wife Michelle it might have not gotten done. He wanted the supercharger to ship on Monday overnight and arrive on Tues. It didnt happen. The supercharger was having to machined from billet since the new molds were not done this took alot of time of course which delay the shipping until Wens 2 days before the event. They finally get confirmation that it had shipped to GA. Problem being they were no longer in GA they were headed to Dallas Tx and were going to have it shipped there where it was going to be changed out and retuned. So Michelle had to get in touch with UPS and track down the location and have it diverted to Dallas for delivery Thursday morning. Believe it or not it showed up Thursday morning. (If that were me I would have given up and gone home! ) He got the supercharger changed out at Jotech shop. Which is really nice of Kenny Tran he usually doesnt let customers work on their cars in his shop.

 

Supercharger is changed out and Kenny starts on the new tune. The new supercharger is now making good boost so much so that the fuel pump cant keep up in the upper rpm range. When the car got to 8900rpm it would start to loose fuel pressure. We really need to go to 10k rpm to hit the shift points and to carry boost levels thru gear changes. So it is 8:30 Thursday night and they have no place to get parts and they really need to leave Dallas that night to get it to Goliad and set up for the race. So they had to leave the redline at 8900 where the car made 410rwhp. Still short of the 500rwhp we were shooting for.

 

7evin get setup for the race I arrived late on Friday. Keith Cox who helped us get to this point flys in to assist us for the weekend. He is incredible knowledgeable and was very instrumental in getting the car together.

 

First run Sat morning was done about 10 am and was done just likely we normally run the car on the track. Front and rear wing were left on we put the upper air foils at the lowest angle of attack removed the front fenders and headlight. We did 143 mph the first run.

We came back to the pits removed the upper air elements in both front and rear wings. Taped up the front grill to limit air movement into the engine compartment. Second run we did 162 mph. (those wings created alot of drag) The car was very stable at 162 with just the bottom elements. Third run we removed the rear wing completely and taped the grill up a little more and ran 167.2 mph. At this time we were fighting very stiff winds about 20 mph that were hitting us on the right side of the car. That was all the runs we could get done on Saturday.

 

Sunday we decided to break out the "secret weapon". Keith had made a nose cone that slipped on and extended the front of the car about 2ft and sloped the nose all the way to the ground. We installed skinny drag tires on the front and slicks on the back for more speed out of the hole. The first run we did 167.3 mph but 7evin noticed the fuel pressure dropped at the end of the run and he had to get out of the throttle. When he returned back we had fuel running out of the rear pan. We began to investigate and found that the seal had gone out on the fuel pump. 7evin had a rebuild kit handy so we rebuilt the fuel pump and found that the bearing had also gone out. This allowed the rotor to scuff the wall on the pump. We got the pump rebuilt had to redo it several times before we could get it to stop leaking. Finally no leaks but still low fuel pressure. So off the pump comes again still nothing can be found. So we scrounge up a Pump from another team adapt it to work in the car and still no fuel pressure. Upon further investigation we found the jam nut had vibrated off the fuel pressure regulator and the stem had backed out letting the fuel bypass. So we fixed that and now we have 60 psi again. We make another run and we still have problems with the low fuel pressure. We decided to stack the pumps in series and it seemed to work with keeping fuel pressure up but we were not able to gain in speed. That was our last run for the weekend.

 

We are going to try again next spring. Hopefully we can have a few more test sessions under it some stuff sorted out by then. 7evin put a fuel pump on there that is massive and lights on the city block dim when it turns on but it pumps massive amounts of fuel. Some more tuning were we can get our rpms up and some gearing changes I think we can reach our 180 mph goal.

Edited November 1, 2010 by WestTexasS2K

[slngsht]

last minute changes are always stressful.

 

couple of comments... first, is the nose cone top secret or can we see a picture of it.

 

second, seems like even 500hp is not a crazy amount of power, so there should be plenty of off the shelf pumps capable of supplying enough fuel. Do you know how many gallons per hour you need?

[WestTexasS2K]

He has a new pump on there now to handle the requirments. Remember we are running on e85 so you need to flow 40% more fuel than gasoline.

 

I have a few pictures on my phone but I will need to download to my computer so that I can post them. I havent been at home much for the last week.

[slngsht]

I didn't realize you were running E85. whole different ball game

[jlumba81]

Is the fuel line large enough? If its too small it might be causing a restriction at higher rpms.

[WestTexasS2K]

Jlumba81

 

We have -8an for supply side new pump seems to be working great.

[Mondo]

10,000rpm! I get nervous at 8 grand... know you've done a lot of work to that motor so it can handle it.

[BusaNostra]

In my estimation, you better off using a turbocharger if you are shooting 500hp and

180mph.....in the downside, it's hot. Turbo can deliver a wider power than the supercharger. Your project probably done by now.

 

90 more horespower to go...even changing the pulley might not do it. You will end up going to a bigger size rotrex than the one they sent you.

They have 3 C38 series --61, 71 & 81 Your original rotrex maybe 61 & upgraded to 81 or something new?

Edited November 1, 2010 by BusaNostra

[slngsht]

In my estimation, you better off using a turbocharger if you are shooting 500hp and

180mph.....in the downside, it's hot. Turbo can deliver a wider power than the supercharger. Your project probably done by now.

 

90 more horespower to go...even changing the pulley might not do it. You will end up going to a bigger size rotrex than the one they sent you.

They have 3 C38 series --61, 71 & 81 Your original rotrex maybe 61 & upgraded to 81 or something new?

remember, they're cutting the revs short 1100 rpm right now too.

[WestTexasS2K]

Busanostra

We are running the largest they make 38-91 not even on the market yet. I agree turbo makes more power. We lowered compression ratio to much also so we will bump up compression and spin it a little harder to get the power. We need a lower gear ratio too that we can get by going with 15" wheels to change final drive ratio.

[BusaNostra]

Busanostra

We are running the largest they make 38-91 not even on the market yet. I agree turbo makes more power. We lowered compression ratio to much also so we will bump up compression and spin it a little harder to get the power. We need a lower gear ratio too that we can get by going with 15" wheels to change final drive ratio.

 

How did you lower it? Did you put a thicker head gasket or a sets of piston?

I believed the stock Honda s2000 compression is 11.1 to 1, this is already very high in

forced induction project. How much compression will u bump up?

 

Lowering compression & rely on big boost is far better than raising the compression

and boost...I hope you can control the detonation. No room for a mistake here.

Your problem is just the supercharger who can't deliver the boost....low compression is ideal.

 

If this is turbo and the compression is low say (8.0 or 8.5), you will not have issue making 500hp. Less detonation then bump the boost!!

Edited November 1, 2010 by BusaNostra

[scannon]

Running E85 makes detonation a non issue until you get to really scary boost levels.

[7evin]

You guys are right on the money on several issues.

 

BussaNostra, We lowered the compression with pistons to 9.5. Which is great for a turbo

motor running pump gas, not good for a supercharged motor running E-85. (Tactical Error on our part)

We were producing 387 Rwhp before we toasted the motor (oil pick up issue) with the smaller C38-61 Rotrex.

This allowed us to redline to 9000 in 5th gear (Road Atlanta 2008)

 

Turbo: I agree with you this would be no problem to accomplish with a turbo.

We choose to do the project with a Rotrex for 3 reasons.

1. HEAT.... The Rotrex unit produces very little and makes living in the cockpit for 4000

mile trips much more bearable.

2. The car is set up to be a road racing/ street car, not a drag car 1/4 or mile.

The Rotrex unit provides a very smooth linear power curve that is very controllable.

Very important when road racing a 1500 lbs car.

3. Packaging. It would fit the hole we had. The air conditioning compressor hole....

 

If I was going to build something to do the Texas mile it would most likely not been a

7 type. (Bad aero) But we were thinking one day..... I wonder how fast this thing will go....

I think the last run of the day we would have broken 170 mph but, I did a 2nd gear launch

and smoked the clutch. (167.4 mph)

I will try to get the video posted of that run.

Pulling off this kind of speed in one mile may not sound so hard when you can run 146 in

the 1/4 mile. But, when you shift from 4th to 5th gear at 150 your rate of acceleration

decreases rapidly. We should have been shifting to 5th at 165. Maybe in March.

 

Slngsht: Fuel pumps.... It is more of a challenge than one might think to find a fuel pump

for this little beast. A couple of things to consider. It has to be compatible with both Alcohol and gasoline.... That is a challenge just by its self...

Next it has to flow enough GPH @ 80 psi to feed 4-1000cc injectors. Next is Cost.

The pump we were using cost $400..... and kept failing... The new Weldon pump....

We don't want to talk about that... because my wife reads this forum and I would like to keep my limbs....

 

Our goal was to try and keep all the components affordable for the car.

 

Thanks for the interest Guys and all the good input.

 

There are some pics @ http://www.usa7s.com/vb/showthread.php?t=2107&page=17

 

and here is the nose.

[BusaNostra]

"If I was going to build something to do the Texas mile it would most likely not been a

7 type. (Bad aero) But we were thinking one day..... I wonder how fast this thing will go...."

 

Me too, couple of times wondering how much you can push an umbrella like 7 car in Texas mile. Something to prove.

If you are going to do this again next year, why not put the low compression piston back next year. I'm willing to give you a Garrett GT35 with .82 a/r in the turbine and a hybrid .60 a/r at the compressor. With the proper mapping, 550 - 600hp is easily attainable. After 60ft hang on, this turbo in full spool all the way to 9k. Turbo is good

for a hi-reviving engine like S2000.

You will not be able to compete with the big boys using the rotrex. Your issue simply

the lack of volume (force induction issue). Rotrex is good for street.

 

Then maybe I will see you next time at Bonneville !!!!

Edited November 2, 2010 by BusaNostra

[WestTexasS2K]

"If I was going to build something to do the Texas mile it would most likely not been a

7 type. (Bad aero) But we were thinking one day..... I wonder how fast this thing will go...."

 

Me too, couple of times wondering how much you can push an umbrella like 7 car in Texas mile. Something to prove.

If you are going to do this again next year, why not put the low compression piston back next year. I'm willing to give you a Garrett GT35 with .82 a/r in the turbine and a hybrid .60 a/r at the compressor. With the proper mapping, 550 - 600hp is easily attainable. After 60ft hang on, this turbo in full spool all the way to 9k. Turbo is good

for a hi-reviving engine like S2000.

You will not be able to compete with the big boys using the rotrex. Your issue simply

the lack of volume (force induction issue). Rotrex is good for street.

 

Then maybe I will see you next time at Bonneville !!!!

 

Hey Busa I am not sure if 7evin will change to a turbo since everything is built and packaged around the supercharger, but my new car will be turbo charged. So I may need to pick your brain a little on turbo sizing. I was planning a GT30 dual bearing unit but they come in different trims and I am not sure I understand the a/r for the compressor and turbine sizing I will have to get educated on that. I will be running a fully built motor as well so it should be good for about 700hp range. I think I will be happy with 450 range for the most part that is what is nice about the turbo just boost it alittle more if you need some more power.

[BusaNostra]

pm sent!

[Mondo]

When I had my tune done at Bisimoto his recommendation was a turbo due to the tweaking you can do across the powerband at different speeds.

 

Instead of needlessly spinning the tires in low gears you can progressively add boost the faster you go. That sounded pretty interesting to me.

 

The AEM ECU also has a traction control function for us drivers with more power than skill to help keep us from wadding up the car. Another thing that sounded interesting to me;)

 

For some reason, I wasn't much interested in the launch control function.

 

 

 

 

,

Edited November 2, 2010 by Mondo

[WestTexasS2K]

Talked with Richard from TTS engineering in the UK he is distributor for Rotrex in the UK and builds some nice kits mostly for bikes but he does alot with Hondas too. He has done some experimenting with CR on motors running the Rotrex and says that changing from 9.5.1 to 11.5:1 will pick us up at least 100 hp. He has proven it a number of times on the S2000, Hayabusa and Triumph motorcycles he builds. So I guess that is going to be our next step is to put some pistons in. Maybe do some head porting and we should be in the 550 -575 range. That should be enough to get us there.

[Hank]

7evin: I can't quote your post on this damn iPhone correctly, but you trap 146 in the 1/4?!? What's your best time to date?

[rnr]

When I had my tune done at Bisimoto his recommendation was a turbo due to the tweaking you can do across the powerband at different speeds.

 

Instead of needlessly spinning the tires in low gears you can progressively add boost the faster you go. That sounded pretty interesting to me.

 

How about turbo lag though? I would think that when you are doubling hp you would have some significant lag while wont be much fun.