A racer friend suggested i short shift into high gear, to my way of thinking that should help me reach a higher speed. More time in high alows that to happen. I never got a chance to try it. I raced a 9.60s mustang on one pass. He ran 139 mph to my 133. He also had me by exactly 6 mph at the 1/8 mark. That tells me he never widened the gap in the second half of the track. Our 60' times weren't much different (1.42 to 1.44) this has me thinking that its all about speed. Am i way off base here?
MPH is horsepower.
ET is bite.
If your MPH is slow for your ET you have an HP issue...carb, fuel pump, ignition, header etc.
If your MPH is high for your ET you have a chassis clutch/converter issue.
133 plus mph correlates perfectly with an et of 10.01. Short shifting and dropping below your best power range average will slow you down.
Spinning will show more mph than dead hooking. I don't know how to explain why but it will.
When the air gets better your car will run 9.80's. The bracket cars at our local track are all .06 to a tenth slower than May and the first of June.
The cam is an improvement. It looks like the 60 ft time is a little slower. That may be because of the poor air, or the larger cam may have hurt torque a little at the hit. Try loosening up the valves .004 (both intake and exhaust) and try one run. I would not exceed .032 with the valve lash.
Thanks Old School. I think you are right. It was 30* C at the track on Saturday so i'm sure it will go faster on a better day. I've also been considering what moves to make next. I've considered a t-ram but don't want to spend that kind of money right now. Plus i don't know if i can handle twice as many carb problems! I don't want to dig into the motor any more. Its been treating me good so i'm thankful for that. Next time it is rebuilt it will get 11 CR pistons. That should be worth 50 hp or more. A friend has an 1150 carb maybe he'll let me try. Right now i'm at 1050.
Brian
My guess is that it's still fat jetting wise, high timing needed to complete the rich mixture. The only thing that has shown a clear back to back change was the timing going up.
Few new things to try with this combo. Gonna try and hit the tires harder. I have single adjustable rear shocks. I've been running them fairly stiff to get slower weight transfer for running them on a slippery no prep track. I found that they would weight transfer to fast then unload the tires as soon as they went all the way. That was with a 3000 chip in my 2 step. Now i'm gonna dial them back so they sink faster and i'm gonna try a 5000 chip in the 2 step on a full prep track. I also re-adjusted my valves to .021 int / .025 exh cold. That should put me real close to where this old used Lunati cam want to be hot (.028 / .032). If i can get this car to 60 foot a 1.35 that should make a big difference on my ET. Hopefully next track day is Aug 5 for me.
Brian
How much power would i gain with this motor if i went from 10.0 to about 11.5 CR ? Say if i took it apart this winter and freshened it up and put in some bigger domes. I need to stay with pump gas but i think 11.5 should be ok with the aluminum heads and a big enough cam. Right now i'm guessing it at about 675 RWHP. (3400 pounds 9.99 ET or 134 mph depending on which calculation i use)
Brian
prairiehotrodder wrote:How much power would i gain with this motor if i went from 10.0 to about 11.5 CR ? Say if i took it apart this winter and freshened it up and put in some bigger domes. I need to stay with pump gas but i think 11.5 should be ok with the aluminum heads and a big enough cam. Right now i'm guessing it at about 675 RWHP. (3400 pounds 9.99 ET or 134 mph depending on which calculation i use)
Brian
Changing only the pistons,I'd say around 30HP/30tq+ on a free breathing engine (no intake restriction or exaust )
The 11.5 CR sounds much better with your cam and engine combo.
'71 Z28 street strip car
Pump gas All motor SBC 427
3308 lbs-29x10.5 Hoosiers
NEW BEST ET
1.38 60' / 4.05 330' / 6.32@111.25mph
cstraub wrote:I would not throw anymore parts at this combo. I would take it to a dyno and see what you have and wear it is. I would try both cams in the engine. This will be the best money spent. With data you can make decisions, guessing just brings on more questions.
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Irony. I just replied to a post and used the dyno example, how they spend big money on an engine, but won't dyno it. Then go to the track 6 times to get it dialed in, and are frustrated and have nothing but issues and are never sure if its right or not. Doesn't make sense to me.
A tunnel ram will give you the same power gain
at least. And keep it on pump gas... 11.5 cr is not going to do that..
Advance that cam if you think the cylinder pressure is suffering..
A stationary stall test on the transbrake to find
the cam position that creates the highest rpm stationary stall test
will dial it in. (max torque at stall will give max stall flash)
They should develop and sell a 2 element torque converter that does not multiply torque (a fluid coupling)
That is a "bolt together" design to allow tuning the coupling (stall) rpm range to allow you to test with it in your car.
Set up the coupling for say 6500 rpm for your motor
and use the transbrake to make very brief full throttle
stationary stall rpm +/- tests. Tune the engine to create the highest stall rpm at wot.
Simply swap your torque converter for this test fluid coupling.
A power glide could be modified to be a stall test transmission, for this stall test fluid coupling.
It would be modified so the output shaft is locked full time.
Like a transbrake.
This won't tell you how much horsepower or torque is being produced but will tell yu when the engine is loading the
test fluid coupling the hardest... (highest test rpm @wot)
That test coupling can be adjusted by simple element clearance
adjustment or varried on the fly by feed fluid control on the test trans. to vary the expected stall range +/-.
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