Thread: Drag racing secrets ?
11-02-2007, 09:42 AM #1
Drag racing secrets ?
More and more I see threads about drag racing and I am wondering how GPR set ups are changing (vs top speed). I would gladly give up 3-5mph to have violent acceleration.
Anyonme care to comment on the must haves ?
I am thinking....
Sealed & properly set pump shoe
Getting the pipe hotter (#3 overboard)
Extended tabs (quicker planing ?)
Leos Holeshot piece for the rear
05 Pump w/extension
I dont know
More timing or higher compression ?
Would a different style of porting apply ?
Are the Non PV 13r motors softer on the bottom ?
Is the GroupK 1390 soft on the bottom because of no Valves ?
To EXPENSIVE for me = Tripples and Skat Pump.
Last edited by mrbtd; 11-02-2007 at 02:18 PM.
11-02-2007, 10:20 AM #2
Single pipe setup
Engine setup: Big bore, Porting, highest compression and tighest squish your fuel choose will allow. Increased static timing with means to retard timing curve at higher RPM's and last VF3 reeds/spacer/matched manifold and BIG carbs!(Novi's!)
Pump setup: `05 pump, DF setback, 85mm exit and 1200 grate
Ski on the fuel busser..................................
11-02-2007, 10:31 AM #3
11-02-2007, 11:03 AM #4
With the larger nozzle and smaller prop I see where RPM's could get higher than 7350....How is that controlled if not with the nozzle combination ?
I.E. Dynafly 14/20 vs 14/24
11-02-2007, 11:04 AM #5
A skat swirl empellor of lower pitch will improve hook-up and excelleration,without the cost of the entire pump.Imho the old style pumps would work just fine for drag racing,the smaller hub allows more water to pass thru for initial take off.A 13/19 would be like a 3:55 ratio in a car where a 12/18 would be like 4:88's,and yes 87mm nozzle!
11-02-2007, 02:49 PM #6
- Join Date
- Feb 2007
- Cape Town, South Africa
Ive been tailoring my setup for leathal acceleration and handling.
Please look at my signature for my current setup.
My future mods will be an efi controller, 170psi head, Custom made Stainless Freeflow and branches (header pipes). Dump #3 overboard. Race Filter with Airbox mods and vf3 reeds. Custom holeshot kit (pity leo;s is soo expensive to ship)
I have the old style pump, that has been blue printed, i dont think you can get a nicer setup once its combined with the Skat type R swirl impellor.
Ive done allot of polishing and filing to the inside of the 85mm nozzle (removing the raised area around the old visibility spout and syphon holes) and its been bored to exactly 86.8mm. the extended R&D trim tabs (old style) allow of quicker plaining, at the expensive of top end speed.
I had a custom jetworks gasket made out of 3mm thick aluminium plate. I let my jetworks valve open at +/- 3700rpm.
Electronic powervalves give a better bottom end, at the expense of reliablity. (im actually debating if its worth keeping them).
Last edited by spaceman; 11-02-2007 at 02:59 PM.
11-02-2007, 03:12 PM #7
11-02-2007, 03:14 PM #8
11-02-2007, 03:56 PM #9
I'm surprised Billy hasn't responded to this thread yet. He is the undisputed holeshot king, and probably has the most info on this.
11-02-2007, 03:57 PM #10
87mm exit nozzle holeshots better than the 85mm?????
Either my unported 1200 makes a hell of a lot more power than the BB on this site or I'm missing something?
I run a stock 14/20 DF and spin it to the moon with a 87mm nozzle. Throw on the 85mm nozzle and it hooks up pretty good. Even with the 85mm nozzle, I have to run the 1200 grate or it spins hard. The only combo that works for me is 85mm nozzle and 1200 grate. And believe me, I know I'm not making much power!
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