Big end power vs lower power & 1/4 mile.

**Stav** · 10-11-2007, 04:47 PM

Playing with the wagon as usual and decided to advance the cam a few degrees to get some more low down vacuum. It worked. The throttle response is alot better and it feels as if it accelerates faster.What is better to have 5 rwkws more up top or 5rwkws across a broaded rpm down low? What will get me down the 1/4 quicker?

SIKSIX · 10-11-2007, 05:00 PM

Stav, we are in the same boat.
Personally i think that top end power will benift because on the strip most cars sit from 4500 onwards for 90% of the run.

I am going to heathcote tomorow and i will bring a few tools and want to run my car as is and then retard my cam and see how i go, im just worried about it running lean, and how much i should retard it.

FS5 · 10-11-2007, 05:35 PM

stav,this is something i've been doing a lot of thinking about lately to.
advancing the cam makes the car so much better to drive on the street,wich is definately a plus.

i think where you set your cam has a lot to do with what rpm its making its peak power and what your rpm limit is set at.
i have found with my cam the best results i have achieved is with the cam advanced 5*.with the cam advanced you may loose a couple of kws up top but you pick them back up down the rev range.
my car as is with the cam set @ 0* makes its peak power 150.6rwk @ 5600 rpm (rpm limit is @5900rpm)but its only making 137rwk @ 4500rpmwhere it ends up starting from when i change gear.when you advance the cam you will loose some of that topend power but pick up more than enough to cover it down lower in the rev range.so when you change gears you have a more usable spread of power.
but in saying that ,increasing your rpm limit will have the same effect.you will just have more usable topend power.
as for wich works best i'm still working on it

FS5 · 10-11-2007, 05:38 PM

Quote:

Originally Posted by SIKSIX

Stav, we are in the same boat.
Personally i think that top end power will benift because on the strip most cars sit from 4500 onwards for 90% of the run.

I am going to heathcote tomorow and i will bring a few tools and want to run my car as is and then retard my cam and see how i go, im just worried about it running lean, and how much i should retard it.

when i had my unichip ,i played with the cam timing and tried everywhere from 5* advanced to 5* retarded.without any probs.just make sure your got good fuel in it

**Stav** · 10-11-2007, 06:09 PM

I remember talking to you via pm some time ago.in the end I put the cam timing at 0 and the car pulled its 14.7 with the dev 4 cam . Now with the headwork and big cam I have advanced the cam in the past few days and its going somewhat better on the street. It is revving harder. I have o say though that the power feels a bit down. After so much playing with the car I can by the seat of my pants know when the car has more power. The car has less but the drive is a lot more torquier. I suppose it goes hand in hand with the theory. I am seriously thinking of a 4000 stall converter and retard this puppy.I hope its streetable..lol.

If I retard this setup then peak torque should move up the rev range and I should have more available. This is a big decision . I can stick with what I have got and keep it very drivable and use the available torque or retard this get more power /torque and stall it higher. I have to think what I want to happen to this car. A ball tearer street car or quarter mile killer.I also have a third option. I can retard this cam and run it at the track as is and hope it gets into the power band.

SIKSIX · 10-11-2007, 06:33 PM

just to make sure retarding the cam means moving the cam anti-clockwise, cause i got some spare time and might do it soon.

**Stav** · 10-11-2007, 10:52 PM

If you do it make sure you have a socket that will turn the whole engine via the crankshaft once your done.Take out the plugs and rotate the engine several times so the pistons and valves don't hit. I learnt this the hard way when I blew my first engine.

**Mechan1k** · 11-11-2007, 08:16 AM

Quote:

Originally Posted by Stav

Playing with the wagon as usual and decided to advance the cam a few degrees to get some more low down vacuum. It worked. The throttle response is alot better and it feels as if it accelerates faster.What is better to have 5 rwkws more up top or 5rwkws across a broaded rpm down low? What will get me down the 1/4 quicker?

I have had mine adjusted to bring more power back down the rev range ... into a more usable area ... and also bring on the torque MUCH lower as well. Aids in drivability as well. Also seeing as I don't rev the guts out of the work ute and being on the road for work loaded up ... this helped considerably for me ... bringing peak torque on around 1700-1800rpm made a huge difference.

Joe has been doing this with a few of the E-series he has been working on ... and dropping a about 5-6rwkw from the top end ... it actually aided in better launching and more torque off the line as well .... and there was a drop in 1/4 times due to this as well.

**Stav** · 11-11-2007, 08:51 AM

This is interesting.there are 2 theories to the story.You have just introduced rock hard proof. Last night after alot of reading I was of the idea that more power and higher rev limit should see an even quicker time. However the facts seem as plain as bread and butter. Its about getting in front staying in front firstly and then if you have a bit more top end power down the straight then thats a bonus.

**Mechan1k** · 11-11-2007, 09:01 AM

Also makes for the more streetable vehicle too.

**Stav** · 11-11-2007, 09:05 AM

I am going to gtech the car soon to see what works better.

**Mechan1k** · 11-11-2007, 09:31 AM

give it a go ... no harm in trying really.

Mr_4.0 · 11-11-2007, 01:25 PM

with an auto, an advanced cam is probably the way to go. with my 1521a cam, and an auto, i had the cam set at 1 degree retarded and it was a slug to get moving but pulled hard to the limiter. now with it set at 4 degrees advanced, the take off is great, and power only drops off a little bit from 5000rpm onwards. much more usuable and i think would work better over a whole 1/4 mile.

FS5 · 11-11-2007, 04:02 PM

Quote:

Originally Posted by Stav

This is interesting.there are 2 theories to the story.You have just introduced rock hard proof. Last night after alot of reading I was of the idea that more power and higher rev limit should see an even quicker time. However the facts seem as plain as bread and butter. Its about getting in front staying in front firstly and then if you have a bit more top end power down the straight then thats a bonus.

this is where it gets a bit tricky in working out which way to go is best.
my theory is ,if you have short diff gears fitted and stally to match where your power is starting to come on....this is the big part ,providing you can get it to hook up off the line ,running the higher rpm powercurve should produce better results at the track.
i'l post some timeslips and see what you can work out.
the slips i ran as car 576 was with the cam advanced 2* and the slips with 762 are with the cam advanced 5*,these were run the same night as my pb.
the 897 one is with the cam set @ 0*.i'm realy only posting this one for the 60ty ,on this run the 1st for the night the car picked up a knock sensor and went down hill from there.
all these runs were done with the car setup exactly the same.only difference being the cam timing.except the 897 one this was before i had chiptorque take some timing out .

FS5 · 11-11-2007, 04:07 PM

heres the rest
http://i220.photobucket.com/albums/d...carbits061.jpg
http://i220.photobucket.com/albums/d...carbits060.jpg

**Stav** · 11-11-2007, 09:07 PM

The gtech and then the track will sort out the truth.