All the prior runs in my car were done with stock cams ……..
We found that the stock cams were a bottleneck to the package when running turbos the size of sport 700’s.
I had 1mm oversize valves and large ports and I felt that the air the heads would move with the larger ports and valves would be good enough and I was afraid to go to larger cams because I wanted as much bottom end as I could keep with the 700 turbos.
Jim at JWT told me we needed the larger cams and when I finally made the change I could not believe the difference in the overall power. The power actually came in much earlier with the 500 cams and instead of falling off it kept making power past red line.
We also found that we could make the same power at much lower boost levels with the 500 cams.
Another benefit of the larger cams is the intake temps are drastically lower and it is much easier on the engine because of this.Since I installed the sport 700 turbos my best 60 foot was 1.55 and most were 1.57 to 1.60 with the stock cams and our standard 5 bolt long split down pipes…….With the smaller A/R HKS turbos I had run a 1.46 60 ft last year and could make 1.50 60 foot times fairly consistently.
The best I ran with the smaller .64 HKS housing turbos was 10.43 @ 135 with 25 PSI and 100 Shot N20.
As far as the new exhaust parts...........
We need to spend some time on the dyno and move parts around and we still have a few refinements to make that I believe will offer even better results. We will need to get some tooling made to accomplish what I have in mind.
But I will give you all some of the details so far……
We took the car to our high altitude track in Palmdale a couple weeks ago to try out the cams and some new prototype down pipes we are working on……..Rather then go full out, I decided to try the new parts at a slightly lower level and ran 20 psi with a 60 shot of N20. Normally at Palmdale I only get 1.60 60 foot times at best because of the higher altitude.
We were able to get a 1.51 60 foot on the first run with slicks and followed with a 1.45 60 foot…….We were very excited about this!!! On to the runs from yesterday……..
We started out running conservative to determine what some changes would offer before turning the wick up……
The changes we wanted to test at the track were exhaust components.
We started off with a prototype split expansion down pipe that went from 2” to 3” with the wastegate coming back into the down pipe at the bottom of the down pipe and pointing straight down the test pipe after it was already 3”. We also had 3” midpipes that has a reducing cone to gradually bring the size back to 2.5” and we ran our standard 2.5” Cat Back.
We made 2 base runs at 21 PSI with a 80 shot of N20 and the results were as follows. First run Second run
60 foot 1.498 1.492
330 4.258 4.239
1/8 6.569 6.529
1/8 MPH 106.82 108.06
1000 ft 8.539 8.482
1/4 mile 10.203 10.138
¼ MPH 135.74 134.12 We felt that this was close enough for a base line and made a change in the exhaust.
We kept everything the same with the engine settings (Boost N20 Timing)
We changed the mid pipes to full 3” and installed a prototype 3” Hyper style Catback that Fast Intentions Fabricated for us on Saturday the day before the race.
The 3" catback exhaust resulted in the following time slip……. 60 foot 1.52
330 4.284
1/8 6.576
1/8 MPH 108.07
1000 ft 8.527
1/4 mile 10.175
¼ MPH 137.00 The 60 foot time you could not say had anything to do with the set up as being that close it could not be said that the conditions or driver were the cause of the small change. The faster you go in the ¼ the harder it is to go even one mile per hour faster. Because of this you can easily come to the conclusion that a full 3” does in fact make more power in high gear.
For a street car only it is still my opinion that the cat back is still fine at 2.5” and you would not notice any significant difference in driving the car on the street by going to a 3” cat back. Also the sound level of a full 3” exhaust is more then significantly louder and for the street I will be keeping the 2.5” exhaust on my car.
So far it does seem like the expansion down pipe and 3" mid pipe do offer signifcant gains, But we still have more testing to do to really have any accurate information to offer you.
It is possible if you go to power levels beyond this that the 3” cat back would make a even more significant difference. I wanted to make another run at this power level without any changes but I ran into a little problem with the track officials…….
After running 137 MPH I was informed by the officials and warned that going greater than 135 mph or quicker than 9.9 require a full cage and a NHRA driver’s license and a whole lot of other safety equipment.
The officials agreed to let me run if I went slower by removing the N20 Bottle.
WELL…….This really screwed with the idea of testing at this power level and I had to revaluate my plans.
I figured retesting at even lower levels would show even less changes and I decided I would take a chance on running harder to try pull off a 9 second pass. Sooooo I took out the 80 shot jets, Popped in a fresh bottle of N20 with 100 shot jets and bumped the boost up to 25 psi.
We keep the full 3” exhaust on to give it everything we had.
I got in the car and crossed my fingers for the officials not to look for the bottle and hoped for a perfect run………
I had been getting good traction all day launching against the converter at 4000 RPM and engaging the N20 as I let off the brake.
The officials did not check me and I decided to take a chance by launching a little harder………
I did not pay too much attention to the tree lights and waited until I hit 4300 RPM and then I nailed it. I could feel the tire starting to slip and afterwards Danny from Fast Intentions confirmed I was spinning……I stayed in the throttle and fortunately the tires bit after about 10 feet.
When the tires finally hooked I could feel the car was noticeably faster…..The real fun came when it hit 3rd gear ……..The power felt like what I would imagine it would be like to have a jet turbine strapped to the back !!!!!!!!!!AMAZING!!!!!!
When I hit the finish line I could hear the rev limiter that was set to 7800 banging off! Basically the perfect gear with the 4.10’s
I was hitting the rev limiter right at the end of the ¼ in direct. So if anyone wanted to know with a 26” tall tire, the 4.10’s are good for 139 MPH @ 7800 RPM.
The pass felt awesome and I had the AFC set to record peak RPM. So I knew based on the RPM the officials were not going to be happy with me as I slowly made my way to the ticket booth……..When I got there the official came out and said “You have a very fast car, You just ran 9.94 @ 139 and you are DONE!” As he handed me the time slip I just grinned from ear to ear and said THANK YOU SIR!!!!!!! The Final slip read
60 foot 1.483
330 4.204
1/8 6.434
1/8 MPH 111.17
1000 ft 8.334
1/4 mile 9.944
¼ MPH 139.78 I have updated my profile on the mods.
Thanks Again Everyone!!!!!!!!
Greg
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