xb et 13.10 need help to crack 12s

[falconsmurf]

set up

xb falcon 3700lbs
351ci approx 217rhp 318lbft@5260
2v heads 4v valves
crow 21649 cam 108/234/244
pedders 90/10 front shocks
pedders soft rear shocks
3800rpm stall
3.89gears
funnel web/850 demon
shift kit
275/15/50s 27high
60ft......1.99
330ft.....5.48
660ft.....8.42
1000ft...10.97
et13.10@102.72
i cant hold stall over 2000rpm on line without breaking was thinking of transbrake though may not suit my combo currently redline over finish line,set tis what is just chasing 2 tenths maybee caltracs?carb is big i know also have 150 n20 shot not ran.all ideas welcom.

[falconsmurf]

correction rear tyres 265/50/15 ...215/60/15 front, radials unknown height crager pro stars,
i have a set of pro stock centerlines which are much lighter,275/60/15 rear 27 high.165/4 inch front runners,will try these next meet and remove tow bar spare wheel to see if i can pick up a tenth

[OBW351]

I was in the same boat as you, sat at 13.0 - 13.1 for ages then went down in tyre size from 255/60/14 to 245/50/14 and cracked 12.94 straight away. i effectly lowered the gear ratio in the rear to get a better hole shot which i carried all the down the track. Have you consided doing something like this?

[falconsmurf]

at the moment i am 6500 revs over the line not sure not sure if a lower tyre will make this worse ,maybe if i dont stall on start line at all i might get better traction and try this option

[gcg2503]

Are you sure the car is 217rwhp or is that rwkw?

217hp at the wheels would be 300hp at the flywheel and no way that power would run a low 13 in an XB

[falconsmurf]

was thinking off either electric water pump or thermo fans to gain a little hp or whether it would not make that much time up

[falconsmurf]

on my dyno report all it says as follows
432nm 318ft/lb
162kw 217 hp
148kmh 5260rpm

[prasac]

caltracs would help a little. set the chassis up as best as u can first see if that is the best time you can get and then go for more power. ur running pretty much on the money, so don't get too stressed, if ur making around 300hp@engine ur going to be running 12.8-13.2's if the *** end is setup good and how good ur shifts are.

try and get ur launch rpm better i'd say the car is bogging down off the lights. pick up a tenth on the 60 and ur into the 12's.

[gcg2503]

I am shocked to say the least. I know 3.89s would make a difference but 380hp in a phase 3 would only run low-mid 14s

I guess my 470hp @ Engine Landau with 3500 stall and 3.5 should crack a 12 then!

[falconsmurf]

and with gas
3 degrees base
710nm 523ft/lb
236kw 318hp
131kmh 5470rpm
et was at heathcoate 3 weeks ago with no gas

[prasac]

Originally Posted by gcg2503

I am shocked to say the least. I know 3.89s would make a difference but 380hp in a phase 3 would only run low-mid 14s

I guess my 470hp @ Engine Landau with 3500 stall and 3.5 should crack a 12 then!

i have tried a few calculators for power to 1/4 mile. this is probably the best online 1/4 claculator i have seen. it's pretty spot on with the Moroso also http://www.rx7.com/accel_calculator.html

[nugget378]

get the 60' down to 1.89 and you will be there, Id try a 750 holley if you have one you could borrow.

[nugget378]

Originally Posted by gcg2503

I am shocked to say the least. I know 3.89s would make a difference but 380hp in a phase 3 would only run low-mid 14s

I guess my 470hp @ Engine Landau with 3500 stall and 3.5 should crack a 12 then!

They measured power differently back then, also tyres are much better now, 400hp will run a mid 12 easily in an XA sedan.

[falconsmurf]

my shift points and take offs are all over the place my 3rd run
was 13.39 105mph 8.60 at half track @82mph
my 13.10 run had same mph at half track,
my 13.32 run had 72 mph at half track 8.63

[falconsmurf]

my brother has a 650 hp i can borrow, my carb 83 size jets in primaries set on rich side,more efficent carb would be better what time gains could i hope for at best if any?my dyno was done 2005,i used 10 litres of av gas to 50 litres of fuel on my runs.

[nugget378]

Try the 650, you might find it improves your short times enough to get that 12, as your not far off.

I use an 850 on mine and it has a 750 on it now, and its a 700hp engine, a conservatively sized carb will usually accelerate well where as a larger one is more difficult to get spot on.

Whats the comp ratio?
You shouldnt need the avgas unless its fairly high, try it on straight unleaded, when you use more octane than needed it will usually make less hp.

[GTP owner]

Some things don't add up.
The power is waaaay too low for the times.
The carby is way too big for the engine (600holley would be better)

Are you having a loss of traction on the start line? If so, a set of slicks is needed. If not, then the caltracs are not needed. The caltracs are required once you start to get axle hop and diff wind-up.

The 60 foot is really slow. Are you bogging off the line, or is it due to wheel spin?

Are you sure about the diff ratio - you should not be hitting 6,500rpm on the finish line with those numbers.

Finally, a trans brake will drop a significant amount of time off.

[prasac]

it doesn't matter what the dyno shows, its track hp that counts. at that weight and mph the engine shows to be making 300hp.

[GTP owner]

Originally Posted by prasac

it doesn't matter what the dyno shows, its track hp that counts. at that weight and mph the engine shows to be making 300hp.

Agree fully.
Makes me wonder if the tune is right given the inaccuracy of the dyno number.

[OBW351]

Originally Posted by falconsmurf

at the moment i am 6500 revs over the line not sure not sure if a lower tyre will make this worse ,maybe if i dont stall on start line at all i might get better traction and try this option

i will check this out in a tick but i was running same gears as you with much smaller tyres running a higher mph and crossing line at just over 6200rpm

something doesn't add up

I worked it out should be around 5500rpm at 102mph with 265/50/15 tyres

[prasac]

if u can get your hands on a Air Fuel meter and check them it wouldn't be too bad. im guessing your located in Vic as u took it down to Heathcote? wouldn't hurt to take it down to someone who specialises in carbies, im not from Vic but i have heard good things about Dandy Engines, if u ask around im sure u can find someone good. i know Melbourne has some good carby guys, some of the fastest carbied cars come out of VIC.

[falconsmurf]

I have not drag raced for 15 years so i will eventully get the car and myself to do consistant times so changes can be made only had 5 passes, 1 st had real bad axle hop, 2 nd spun all way to 2nd gear,3 rd took off at 1000rpm then stepped out as i hit 2nd;4th cant remember cause i was staging and trying to put my long sleeved shirt on at the same time which i forgot 5th felt like i hooked up 1 sec after launch.My 60 ft times were 1.99 to 2.19 , diff is 3.89 mini spool

[GTP owner]

Alright then. The biggest improvement will come from a set of slicks or drag radials on a cheap set of steel rims

[smally289]

Agreed, a set of ET Streets will show a big improvement.
http://www.vpw.com.au/product.asp?Ca...3&ProdID=99869
27 x 10.5 would be my choice. A big baggy tyre will give better traction than a low profile like you have now.

[Giant]

Originally Posted by falconsmurf

correction rear tyres 265/50/15 ...215/60/15 front, radials unknown height crager pro stars,
i have a set of pro stock centerlines which are much lighter,275/60/15 rear 27 high.165/4 inch front runners,will try these next meet and remove tow bar spare wheel to see if i can pick up a tenth

Would use the front runners for sure pump them up hard. Sticky tyres for the rear what ever you prefer. Have you remove the front swaybar if not give that a try.

Battery moved to the boot more weight where you want it over the rear wheels.

If you don't get sticky tyres removing the tow bar and spare will just result in more wheel spin and slow times.

Adding more fuel can add enff weight over the rears to help you hook up worked for me last round actually i hooked up too good and got a red light lol.

Are you running thermo fans they are a good upgade to belt driven fans. Install a switch to stop your alternator charging when you got to burn out box.

[falconsmurf]

got a thermo fan today,battery is in boot,tried to find caltracs but ran out off time having trouble finding some now,transmission gets a better oil cooler and service next week,not sure if i look into engine oil cooler temp goes up to 220-230 at the moment thermos will help,thanx for help as im learning all over again

[landau_jon]

351ci approx 217rhp 318lbft@5260

you will probably find this is 217kW or 290rwhp

[Giant]

Try a better oil and play with spark plug gaps and types and make sure your air filter is high flow. Are you using a fuel pressure regulator? What fuel are you running you could try BP 98 with Nulon Pro octane booster it will get you up to around 100 octane which would allow you to advance the timing a little more.

If you using street radials after the first burn and run try good way to clean them and get some track compound on the tyres. Try driving around the burn box / water as the water tends to make the street style rubber slippery and most burn outs don't create enff heat to dry them and you just end up with a slippery tyre.

check the tyre pressures after each run when the tyres have cooled to make sure they are at the correct psi try 24 psi in the rears.

[Giant]

No sure what style thremos you picked up but the work best with some sort of cowling. A lot people seem to be fitting the BA twin style fan setup about $50 from the wreckers these move 3000cfm per fan.

[Parfrey]

As others said, you need some decent tyres!
No point going to a transbrake if you not even using close to your 3800 stall.. if you have traction issue's good tyres will get you straight into 12s