Thoughts on this TT cam?
Thread Starter
Heel & Toe
Joined: Jun 2019
Posts: 24
Likes: 0
Thoughts on this TT cam?
New cam specs
I have a basic understanding of the attached cam specs but I'd like to know more.
Is this cam meant for high rpm or strong mid range?
I installed it a few weeks ago and just started tuning it the car.
It's in a 1999 C5 (Ls1)
6 speed manual.
STS twin rear mount (T3/T4 highbrid 46mm compressor / .36 A/R exhaust.
65lb injectors.
Everyting else is stock on the motor.
I Haven't gone more than 1/2 throttle yet but so far the idle is nice and Lopey. My low end is a little weaker than before but Its tolerable.
What are your thoughts? What kind of performance change can I expect compared to the stock LS1 cam? (Ex: more mid range or more top end)
Also.. before anyone goes bashing me for going with an STS kit look at my "mustang dyno" sheet. I dynoed it on 93 pump gas with the stock cam. Did all the tuning mysellf with HP tuners (2 bar SD tune) @ 9lbs of boost, 11.0 AFR and 10 degrees of timing the 100,000 mile Ls1 made 580whp / 641wtq.
Thread Starter
Heel & Toe
Joined: Jun 2019
Posts: 24
Likes: 0
I dynoed My truck there a while back. Its got a 5.9L Cummins that's running 60lbs of boost through compound turbos with big injectors, lots of meth, ect and I only made 630 whp through a manual 5-speed. the torque was pretty nice though, lol.
Last edited by USCG MK; Jun 17, 2019 at 02:06 PM.
Burning Brakes
Joined: Sep 2011
Posts: 764
Likes: 19
From: odessa FL
Comp has a series of cams that at least at one time were noted to be for rearmounts- hence the reversed duration pattern. This was for the inherent lag problem.
I have the one that is the next step down [`227 degrees] but not in yet.
I have a stock cam but with bigger turbos
This one may be a bit large for a stock size engine. It would be better for top end or to bleed off some static compression.
How much gear are you running?
An electronic controller may help the spool
One thing nice about a bit of lag on the street is it gets the car to hook before the boost hits.
I have the one that is the next step down [`227 degrees] but not in yet.
I have a stock cam but with bigger turbos
This one may be a bit large for a stock size engine. It would be better for top end or to bleed off some static compression.
How much gear are you running?
An electronic controller may help the spool
One thing nice about a bit of lag on the street is it gets the car to hook before the boost hits.
Thread Starter
Heel & Toe
Joined: Jun 2019
Posts: 24
Likes: 0
Comp has a series of cams that at least at one time were noted to be for rearmounts- hence the reversed duration pattern. This was for the inherent lag problem.
I have the one that is the next step down [`227 degrees] but not in yet.
I have a stock cam but with bigger turbos
This one may be a bit large for a stock size engine. It would be better for top end or to bleed off some static compression.
How much gear are you running?
An electronic controller may help the spool
One thing nice about a bit of lag on the street is it gets the car to hook before the boost hits.
I have the one that is the next step down [`227 degrees] but not in yet.
I have a stock cam but with bigger turbos
This one may be a bit large for a stock size engine. It would be better for top end or to bleed off some static compression.
How much gear are you running?
An electronic controller may help the spool
One thing nice about a bit of lag on the street is it gets the car to hook before the boost hits.
Honestly I'm not sure on the gearing, I believe it's the stock gearing that came in the 1999 C5 base models with the 6 speed. I bought the car used though so I'm not 100% sure. Everything was stock as far as I could tell when I got it.
I'll let you know how it runs when I get it back together, I've got the heads off now to change the lifters. Hopfully it works out well enough for now.
I'm going to build the motor eventually but I don't want to do another cam swap right now. That power steering rack was a bitch..
Last edited by USCG MK; Jun 18, 2019 at 09:25 AM.
Pro
Joined: Feb 2003
Posts: 745
Likes: 136
From: Detroit MI
That's a lot of duration and a lot of overlap. Both of which are not in favor of making good exhaust gas velocity for the turbo. (Even worse transient response when the turbos are more then ten feet from the engine) I wouldn't expect miracles at moderate boost levels with it.
Burning Brakes
Joined: Sep 2011
Posts: 764
Likes: 19
From: odessa FL
I dont see that much overlap- its on 115 LSA- but agree it may be a bit much duration for the application.
Stock gears woould have been 3.42. I run 3.91 and it works great
Looking at both dyno sheets I see a problem with the RPM scale. THe crossover point for torque and RPM is always at 5250 due to the mathematics involved.
Im not that familiar with diesel dyno sheets but the same should apply. Wow... massive torque- someday I want to play with a diesel.
My feeling is that dyno is a little optimistic. Running same setup [maybe bigger turbos], 10#, 11 degrees meth and dead stock engine I got 534/556 and a much flatter torue curve. Also, power didnt start to drop until ~ 6k. Ill see of I can find my sheet
Stock gears woould have been 3.42. I run 3.91 and it works great
Looking at both dyno sheets I see a problem with the RPM scale. THe crossover point for torque and RPM is always at 5250 due to the mathematics involved.
Im not that familiar with diesel dyno sheets but the same should apply. Wow... massive torque- someday I want to play with a diesel.
My feeling is that dyno is a little optimistic. Running same setup [maybe bigger turbos], 10#, 11 degrees meth and dead stock engine I got 534/556 and a much flatter torue curve. Also, power didnt start to drop until ~ 6k. Ill see of I can find my sheet
Last edited by StatmanRN; Jun 18, 2019 at 07:50 PM.
Thread Starter
Heel & Toe
Joined: Jun 2019
Posts: 24
Likes: 0
Finaly got a chance to do some tuning and open it up a bit. Ran it up to 6,200 on 9psi and it was still pulling pretty hard. It builds boost a little bit slower now but It definitely picked up some power towards the upper mid range / top end. Before it would hit verry hard in the mid range (harder than it does now) but it would die out after 5,500.
Over all I'm pretty happy with it. Its got a little more lag now which is not as much fun on the street but ive only just started on the tune.
I know it is a little too fat during transitional throttle to wide open. Hopfully as i dial in the VE more and play with the timing it will help.
Thanks for the responses.
Anybody got expirence with tuning for faster spool up?
Over all I'm pretty happy with it. Its got a little more lag now which is not as much fun on the street but ive only just started on the tune.
I know it is a little too fat during transitional throttle to wide open. Hopfully as i dial in the VE more and play with the timing it will help.
Thanks for the responses.
Anybody got expirence with tuning for faster spool up?
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Pro
Joined: Feb 2003
Posts: 745
Likes: 136
From: Detroit MI
Slightly rich of stoich (lambda = 0.95ish) and retarded spark will put some extra energy in the exhaust to help spooling. There will be a balance between enough spark retard to raise exhaust temps and losing useful work on the piston to make torque right now.
Thread Starter
Heel & Toe
Joined: Jun 2019
Posts: 24
Likes: 0
It's a 6 speed. (T56)
Already got a boost controller on it. Spring / low boost is 5 psi. High boost with controller on is set at 9psi.
I think I'm going to try and tune it like a NA motor untill it gets into boost.
Ill Shoot for 12.8 AFR and between 22 and 26 degrees of timing up to 100kpa and then richen it up from there all the way to 11.2 @ 9psi. That'll be my target afr while spraying a good amount of water meth, 50/50 mix.
Already got a boost controller on it. Spring / low boost is 5 psi. High boost with controller on is set at 9psi.
I think I'm going to try and tune it like a NA motor untill it gets into boost.
Ill Shoot for 12.8 AFR and between 22 and 26 degrees of timing up to 100kpa and then richen it up from there all the way to 11.2 @ 9psi. That'll be my target afr while spraying a good amount of water meth, 50/50 mix.
Last edited by USCG MK; Jun 26, 2019 at 03:16 PM.