44 replies to this topic

[boblhslr]

Hi guys was just wondering what combos guys are useing to run into the 12's. I am running 13.05@106mph in an lx. Just looking at what I can do to run mid 12's. Maybe a cam change or diff. I am running HQ red heads ported and polished to l34 spec, a crow cam #5649, roller rockers, comp is 11:1 static, flat top pistons, stock stroke, 3000 stall, turbo 400 and a 9" with 4.11. My 60foot times were a best of 2.02. for the quest for 12's I changed the converter for a 3800rpm and box to a turbo 350. In doing this change I have actually lost time and mph. 60ft times have dropped to 1.94sec but the rest of the run gets worst. Abest time of 13.40@101mph. My rpm accross the line has increased to by 300rpm but has lost mph. My car wieghs 2820lbs with out me.
Any ideas on getting my car into the 12's. Was thinking on going to a bigger camshaft, maybe a crow #5802.
Thanks guys
P.S
I ran the 13.05 with an performer manifold and have now changed to a redline maxitorker manifold. We ran the maxitorker with the turbo 400 for 1 meet with a best of 13.20@104mph. This was put down to the weather being very humid. Then the box and converter were changed and the car went slower.

Edited by boblhslr, 20 February 2011 - 06:12 PM.

[tor308]

Hi guys was just wondering what combos guys are useing to run into the 12's. I am running 13.05@106mph in an lx. Just looking at what I can do to run mid 12's. Maybe a cam change or diff. I am running HQ red heads ported and polished to l34 spec, a crow cam #5649, roller rockers, comp is 11:1 static, flat top pistons, stock stroke, 3000 stall, turbo 400 and a 9" with 4.11. My 60foot times were a best of 2.02. for the quest for 12's I changed the converter for a 3800rpm and box to a turbo 350. In doing this change I have actually lost time and mph. 60ft times have dropped to 1.94sec but the rest of the run gets worst. Abest time of 13.40@101mph. My rpm accross the line has increased to by 300rpm but has lost mph. My car wieghs 2820lbs with out me.
Any ideas on getting my car into the 12's. Was thinking on going to a bigger camshaft, maybe a crow #5802.
Thanks guys
P.S
I ran the 13.05 with an performer manifold and have now changed to a redline maxitorker manifold. We ran the maxitorker with the turbo 400 for 1 meet with a best of 13.20@104mph. This was put down to the weather being very humid. Then the box and converter were changed and the car went slower.

Hey mate, you didnt mention what carby you are running , or if a spacer is used
Are you running pipes on, pipes off? What tyres are ya using. eg diameter/height

Sounds like the new convertor might have too much slip in it. What rpm are you actually crossing the line at

[Lima31]

Tyres?

Could be something simple like enough fuel and spark under all that load and acceleration. E.g. if carby, getting enough fuel pressure at WOT? Fuel could be sloshing under acceleration.

I'm sure there's a guru with an answer here

[boblhslr]

Hi guys, I am running a 650dp holley carb. I am using a 1" hvh supersucker spacer. The 13.05@106 was with pipes off but only had 2" system. Now have 2.5" system that terminates in front of the diff. I am running 3/8 fuel from a cell to the carby. The tyres I am using are 26x8.5x14 hoosier slicks. The fuel pressure is stable through all rpms but haven't tested it under load. The distributor is electric with a coil and 8mm leads.
Thanks guys any gurus out there?

[Toranamat69]

Traction could be a good place to start looking for some improvement.

I have a manual and a nasty clutch and I can pull pretty consistant 1.67s 60 foot times on street tires with 12.52ET and 114Mph. I have a 9" with 4.11 gears as well - I do have tall rear tires (660mm OD).

I would have thought you would be able to match those 60 foot times with an auto with good tires.

What have you done with your upper trailing arms on the diff? My upper diff mounts are 1.25" higher on the diff housing than std. You can achieve similar by drilling the front mounts 1" lower than std. Might be worth a try. I would say try some softer springs in the back but mine are hard as hell to do the times above.

Could also try some adjustable control arms - I have these too but I havn't adjusted them from std length yet.

I have run a few guys with LX's who have round the 106Mph terminal speed and on drag slicks they are pulling high 11's so I am still leaving a fair bit on the table with my street rubber.

It makes a fair difference with driving style to do the 1.67 - 60 foot times above, you have to roll the power on to get the weight transfer to the rear, then give it full blast. Full blast off the line just results in massive wheelspin.

Your new converter may be to high a stall and you may be loosing some of the meaty bit of your torque curve - it is the torque which accelerates you, not the HP. You don't just need a harder push off the line(quicker to 60ft) you need to push for longer as well - this is what is meant by usable area under the torque curve. Do you have a dyno printout of your engine? or a good idea of the torque band?

[wot179]

You blokes are making it sound complicated.

You changed manifolds,and ran less mph.

Change it back and see what happens.

107mph should run a 12 without too much trouble.

You are losing most of your time in your 60.

That is usually traction ,gears,or the way you are stalling it up

.I reckon your gears are spot on,so that leaves traction and stall.

There are two schools of thought on stalling it up.

One says hold it a bit over idle and mash it,letting the converter flash and pull you out of the hole hard.

The other says hold it as high as you can rev it without sliding the tyres,and mash it.

I know people who have suceeded with both methods,so try both and see what works best for you.Personally,letting it flash from 2500 worked great for me.I was using a glide and a 5000 converter.


OK,Traction.

90/10 shocks up front,50/50s in the rear

6 cylinder springs in the front.

Remove your front sway bar.

Then start playing with tyre pressures.

If you are running radials,you wont do much better than the minimum reccomended tyre pressure.If you drop them heaps the rim will just spin in the tyre.

Slicks or McCreary type street tyres,start at about 14 psi and work your way down 1 psi at a time till your 60s start getting worse,then go back to where they were best.I doubt you will ever need less than 9psi.

The trick is to only ever change ONE thing at a time,or you never know what made you go quicker.

Thats my 2 cents,hope it helps.

[Struggler]

OK, here is my take on it.

First refit the Performer with the HVH.

The new converter may be a bit loose but don't change it back just yet.

Your 106 is enough MPH for a mid to high 12 so you are losing something down low, look at timing and fuel (get as much initial timing as possible).

Get a baseline and go from there, one change at a time.

[unclefestal34s]

like wot179 said one change at a time 106mph is 12s numbers and your pretty much on the mark at 13 zero perhaps thats all that has left in it..

[boblhslr]

Hi guys thanks for the reply's. I am running crossply slicks and I am not having any problem with traction atm. I have tryed many different ways to stall but nothing seems to work. Always 1.9? with the new converter.
I never had the chance to run the hvh with the performer manifold. I might give that a go. As for timeing I am running 15deg intial and 32 total. 32deg by 3000rpm.
As for carby I am useing a 650dp with 37 squirters, 65 mains in the front and 74 mains in the back. It also has 4.5 power valve.

[boblhslr]

like wot179 said one change at a time 106mph is 12s numbers and your pretty much on the mark at 13 zero perhaps thats all that has left in it..

Yeah thats what we were afraid of and thats why we were thinking maybe a bigger camshaft maybe in order.

[boblhslr]

Hi guys.
At the moment I am crossing the finish line at about 5600rpm. Going to put the old performer manifold on first and see where that leads with the bigger stall.
Thanks guys

[boblhslr]

Hi guys,
Went racing last night and have a new pb for this combo. Ran [email protected]. Only miner changes so far, changed the front squiter in the holley from a 37 to 31, left the rear squiter at 37 and add a funnel in the air cleaner to direct air down through the carby. I was going to change the manifold back to the performer now but it looks like we are going to remove the gearbox and converter to get it checked due to some strange noises coming from the box in the brakeing area when slowing down. It is also making strange noises when stalling up on the start line. So gearbox first I think.
Thanks Mitchell

[jlkass1]

As a few others have said - you have the mph...its the take off...I have a similar combo, HQ headed 308, precision dual plane manifold with a 2in spacer and 650 DP...stage 3 trimatic w 2500 stall & 9in 4.11s...PB to date is 12.6 @ 107mph, crossing the line @5800rpm on 225/75/15 street tyres...& full exhaust - twin 2 1/2 inch all the way thru....sounds like you have it there - just need to sort it out...I'd try a 1 or 2inch spacer, they're good for torque off the line. Good luck with it anyway.

[boblhslr]

Hi guys thanks for the replies. I haven't removed the box yet. I am deciding whether to pull the motor at the same time and replace the cam at the same time. Also have a holley hp street 750 I might try once it is back together. Will let you guys know how it goes.
Thanks Mitchell

Edited by boblhslr, 07 March 2011 - 09:07 PM.

[boblhslr]

Hi guys
Have found the source of my gearbox noises. Turns out the turbo 350 has a crack from the bell houseing down around the side to the pump. As my block is a trimatic pattern we have decided to go back to a trimatic box. While the box is out we have decided to pull the motor and check it out. We've had the heads flowed. Intake flowed 201cfm and the exhaust flowed 80% of the intake. What is everybody thoughts on camshaft choice to put in it. Red heads, stock stroke, trimatic, 4.11 ratio and a stripmaster manifold.
Thanks any thoughts.

[warrenm]

Bad luck with the tranny. Take all your specs to a cam manufacturer, as they will give you a cam to suit needs, not one that someone has used for their application.