I want MORE on pump fuel some engine options for the pro's

[SPEED]

a7, I am taking my sled to the dyno on the 21st. of Nov. I have an attak with the mpi s/c with 26/24 pulley set-up. Am running this thru the Excell exhaust, so I will be able to give you some real time results when I am done. Jim at Dyno-Tech will be tuning it.
I can forward the results to you when finished, Hope it will help you out.
Art

 

[TurboJamie]

I would GREATLY appreacite that sincerely. That would save me a ton of time. We were going to dyno mine at the end of November as well but if you are already booked then I'll forget about it. If I have my whiteknuckle by then any interest in dynoing it as well if I mail it to dynotech or yourself?

 

[SPEED]

I don,t know that I will have time for the switch,my son is taking his mach z and has the afternoon all tied up allready. but I will be glad to send the results to you or you could join us at the dyno .I know Jim wouln't mind.

 

[TurboJamie]

Humm another possibility let me play with my schedule and see if I can get down there that would be awesome.


For those following along am I doing this right for the speed calculator

Engine RPM 10,800
Gear Reduction 1.23
Clutch RPM 8700
Pitch 2.52
Clutch Ratio 1:1
Gearing 25/38
= Top Speed of 122 MPH

Now my clutch isn't cut im just using and aftermarket helix this must mean Im getting past a 1:1 shift ratio then.

My next question would be wouldn't it be better for me to get my clutches cut for OD and go back to say a 24t top gear?

 

[grader]

mph formula is teeth top sprocket x track pitch x teeth drive sprocket x 60 divided by teeth btm. sprocket x 5280 x 12 x clutch ratio. this works out to 124.42 mph with your gears assuming 9 tooth drivers and 1:1 clutch ratio.

 

[TurboJamie]

That means I must be seeing about a .95:1 ratio to turn the MPH I was last year so these do have a slight overdrive stock. I wonder how much I can get from cutting em a .90 would be nice.

 

[rxrider]

According to my measurements and math bone stock clutches have a ratio of 0.977:1 at full shift with a new broken in drive belt with 20-30 miles on it. If your tackometer is spot on running 10800 your primary clutch spins at 8757 rpms giving a theoretical top speed of 126.6 MPH. You are very close to running out of gear running 122 mph. If you have a machined/aftermarket helix your clutch ratio is close to 0.93:1. If you can raise the drive belt to the top of your primary your clutch ratio will be close to 0.85:1 - Clutches are most efficient running at a clutch ratio of 1:1 tho.

 

[TurboJamie]

Thanks for the reply. I understand the 1:1 ratio being more efficient however to hit my top speed, I cannot change the gears that much more or I will start to loose accelleration. I am already at a 26-38 and I am running BIG mph but I want to step back to say 24-38 gain accelleration but still be able to to run 130's keep in mind with a machined clutch how often are you going to be running at the top anyways? Its only for the odd lake race of 2000' not day in and day our radar running.

I have done some calclations and come out to about the same Jan about a 3-5% overdrive in these clutches if I could hit 10% I would be happy. Afterall the doo clutches are .83:1 and we have run them for years without problems of being that inefficient I figure I have the power to turn em!

 

[rxrider]

Yes I know them machz's, brother-in-law had a 1999 lt until a few years ago. It ran great top end but it blew belts quite often vs the SRX700, the 8DN is quite strong tho, it will hold up. You'll get great bottom end pull and fast accel and still get a desent top end going with a machined primary/secondary combo. I did run OD clutches in my piped 2001 SX700R with good results. With both primary and secondary clutches prepared for OD you will get close to 0.84:1, and yes you have the power to run it into OD Running 24/38 for gearing, the theoretical top speed will be close to 140 MPH, but due to clutches beeing less efficient at OD your top speed will more likely stay closer to 130 MPH than 140 MPH. Keep us posted

 

[TurboJamie]

If I can bust 135 mph in 2000' I was only 2 off last year I will do this dance out on the lake.

 

[rxrider]

Good luck, I hope you can break that barrier, you're close.