Txboatman

I posted this in tech and didn't get much response. Maybe this will be a better place.

I have read up and done a good bit of research on cams but I would just like to get some feedback on them from people who run them in their c5.
Here is the car build and my intended use and requirements.
99c5 A4 3200lbs with driver
4.10 rear
3600 circle D stall
TSP long tubes and 3' off road pipes. No mufflers
Fast 92 intake 90mm ls2 TB
Vararam. And a dyno tune.
Drs and skinnies up front.
The car is used 80% at the track as a bracket car. I occasionally drive the car to the track or go for a little cruise on the weekends down back roads where I can play. I plan on taking care of all the associated parts when doing the swap ie, ls2 timing chain, new oil pump, electric water pump, lifters, trays, pushrods, springs and trunion upgrade. I will also be adding a set of untouched 243 heads.

This motor has 2 race seasons and 150k miles on it so I don't want to spin a crazy amount of rpm. What cam would the knowledgable members of this forum suggest with my setup that would allow me to keep the shifts around 6200-6300 rpm. Range, work with my stall and keep this thing going till I have a forged motor built with a different set up. Any input is appreciated. I am sure when the time comes I will get with a vendor and have a custom grind done, just wanted to do a little bench racing.

LSOHOLIC

Couple questions to help with your decision making process.....

~what elevation do you run the car at ??
~what fuel will you be running ??
~what head gasket thickness ??
~what bore and stroke (cube) ??
~are you trying to squeeze every last drop of hp ??
~are you wanting/willing to flycut the piston ??


.

Txboatman

I will go down the list.
Sea level.
Pumpgas
Stock or a .40 if I can get away with it
Stock cubes
No. I need something that will shift out at 6200-6300. maybe higher if needed to attain that et.and will work with a 3600 stall and 4.10 gears.
I don't want to mess with the enternals. I plan on running this set up for a season or two while building a forged motor.

I don't need a screamer but I would like to go fast enough to run the 7.0 index classes. Have t ran the car since adding the skinnies but if what everyone says is correct the car should do 11.6xx ish in average conditions. So I need .7-.8 within the parameters given. I am thinking something to the TSP 233/239.

Rob Petyo

The stock (untouched) heads throws me ... why ?

And I'm curious what you are running in the qtr now with the 4:10's in an auto. I would have thought you would have ran out of gear in third with that setup. If you arent now, you probably will be with the added hp.

Tar Heel

I am in the exact same boat. Almost the same set up.with similar goals. I've done a lot of research, here and on the LS1 Tech forum, and think I'm going to call Brian Tooley for his Stage IV cam. For now I'm going to leave the stock 241 heads on and see if we can achieve our goal. Our best ET bolt-on (ok, stock lift stock durwtion cam) is 11.58 so i need about 6 tenths to go 10s and then we are going to spray 150 and try to go 9s. If we need more ET after all is said and done I might have Phil at AI do a set of 243s or even do my stock 241s depending on how close we are.

Scott

Tar Heel

Also, our best 1/8 mile ET is 7.29 and we run the stock LS6 intake so you may be closer to the 7.0 index than you think.

Scott

Txboatman

@ Hotweels. The heads is a money thing. I can pick up some 243s for not a lot of money. If I was just digging into the motor the cost would be fine but have a lot of other stuff that I have to do to the car next off season, mainly a cage and the drive train. I think I can make my goal without aftermarket heads. Car is currently running 11.7x @ 114-115 with a 250-900' DA. I added gto rims that I had polished with a M&H skinny tire last time I was home but haven't been back to the track. Should be in the 11.6x range on average now.
As for RPM I am crossing at 6200 ish now. This will be the last season on my 245/40/18 They are 25.8 tall. Depending on estimated trap speed of 122mph if I ran a 275 on my front rims I should cross at about 6450. I think I will be ok setting my limiter at 6700. Righ? Or is my speed assumption too low? I think at 125 i would still be under 6500. if i had to i could go taller on the 18' rim. Any feedback is appreciated.
The car shouldn't see it much as almost all bracket racing I do is 1/8th mile now. Will only be doing the quarter for testing.

Txboatman

Thanks Tar Heel. That cam set up you have must be helping you out a bit. I saw in another thread you put down 370ish, correct? I put down about 340 on a hot motor, similar mods but I have the older style heads. My 1/8 before the skinnies is 7.46 damn near every pass. I think the 243s and cam should get me 70hp. That should be enough.

Rob Petyo

I actually feel your speed assumption of crossing at 125 is too high - we'll have to see but I can't see picking up another seven MPH. With that much MPH you would be way into the 10's.

Txboatman

Is 120-122 a better estimate. If that is the case I guess I will be able to stay on a 25' tire

Rob Petyo

Sorry, I really don't know & with the gears (4:10's) you are using in the auto, I don't know of anyone else going with that much gear. I may be wrong but I feel in order to get closer to the MPH you need/want, you would have to add more hp to it and less gear but that will affect everything you have now.

Tar Heel

Yes, I'm sure that cam helps but I don't know how much and am not convinced that it is anything measurable. I say that because when we put the cam in I also added the 1 & 7/8" ARH LTs, off-road x-pipe, UD pulley and beehive springs. We picked up 50 rwhp from those changes and our tuner said he expected that gain from just the headers, cat-deleted pipe, pulley and fresh springs. When I change cams again I will just do the cam and springs this time so I'll get an accurate HP gain.

Txboatman

I guess I will just have to figure it out. I have a fairly good idea of how it will run. Now I still need to figure out what cam to run win this set up. I plugged all the rpm numbers in and as long as I run under 125 it will be ok on the 25'' tire. You got good gains on your combo. With everything I have done so far I am only at 50whp. Hoping the fast intake really helps the cam I chose make power.

PRE-Z06

Granted I have a manual, but have been 10s with ported 5.3 heads, baby 218* cam and 4.10 gears on a 26" tall tire. I have to shift to 4th(1:1) right before the 1/8, so only went a 7.03@98 on a 1.49 60' in ~600 DA. I went went 7.09@101 before I made the trans gear swap with 404rwhp and confident it would have gone 6s easily. The rule of thumb for .1/1mph gain for 10hp is for the 1/4 and roughly 60% is all you see in the 1/8 from my experience. Not sure of the conditions when you made the previous passes. Here's a calculator to help if you want to play around with tire heights and rpm...
http://www.f-body.org/gears/

Where are you located? BTW my ported 92 FAST was worth 10hp over LS6 intake and ported heads, personally I'd do a TPIS 90mm modified LS6 if running 243 heads. Feel free to give me a call.

RonSSNova

I have to chuckle at your accomplishments with a measly 404hp. Where are the 470 WHP guys? Should be in the mid tens easy, yet most are in the mid 11's.
" What's it puttin down man? "
:-)

Nice job.

Ron

Txboatman

@ Prezo6: I think at this speed your HP to ET gain numbers are spot on.
I looked at pics I have of old time slips and that seems to be what I am getting. By that formula I will need 70hp. Now that is established back to what cam should I be looking at to shift out at 6200-6400 with the limiter to 6700. Am I in the ball park with the 243 heads and Tsp 233/239?
When I bracket I am leaving stalled up to 2k for consistency and I like to hold some time that way. I have only two 1/4 mile passes and I was launching soft like that. With the new front tire/rim combo and bring it up to 2400 I might be able to wring the car out a tenth or two more over my current 11.73. I get off hitch in two weeks and will hopefully get a few good passes in while off. I am determined to take the #3 spot on that bolt on list before I dig into this thing. .

PRE-Z06

Thanks, the 470rwhp guy went 9s lol

Our dyno may not be as generous as others in the area, but we don't sell hype. For comparison we had a customer bring us a CTSV that was bought in the northeast with a dyno from Tune Time and it was within 1rwhp

PRE-Z06

That's not a bad cam, but would spin it to 7k rpm and uses a 4k stall. I'd spec something a little smaller that maximizes DCR and makes better torque personally. I assume you're in Texas and like to fish as well?

LSOHOLIC

To the OP.......IMHO you need to get your drivetrain nailed down before you start looking at camshafts.

Most any 23x/24x, Fast, stock 243 headed, full bolt-on 346" will be in the 440-460rwhp range on a dyno jet and peak tq will happen @ 4600-4800rpm and peak hp will happen @ 6500-6700rpm. Take that info to your convertor guy and nail down your combo.

Things that should be very important to you if you plan on going fast.....(before you pick the cam).
~shift extension (rpm fall back)
~SLR (starting line ratio)
~rollout
~rear gear (based on trap mph & rollout)
~convertor (slip %)
~maximum rpm motor will turn

Now, with this info.....pick your cam based on what the "car wants" and is going to do going down the track.

In a perfect world, rpm drop would fall 400-600rpm after peak tq. This is where it would "pull" the hardest. All of this needs to be tweaked with convertor, rear gear and trans ratios.

And it get a real world grasp of the cam duration numbers.....crunch the cam nubers given to you by your vendor of choice, so you can compare what is really going on with the valve events.

Good luck with your setup.

.

C5 Pete

FWIW,
My 11.0 set up was as follows..

2001 Z06 with a 4L60 conversion 3200 lbs.
Yank SS4000 converter
3.42 rear
GM Hot Cam. Yeh that's right. 219/228 with .525 lift and I think 112 LSA. Look it up.
243 heads milled .030 and a valve job. No port work at all.
FAST 90/90 TB.
Kooks headers/x pipe. No cats. Ti cat back.
Stock push rods.
Stock water pump.
Melling oil pump
Under drive pulley

CCW drag pack. M/T 255/60/16 drag radials

Doug@ECS tuning

11.0@121 with a 1.51 60'. Launching at about 2000

Great consistent bracket car...May she rest in pieces...

Bigger is not always better...

Good luck with your goals.