old motorhead

Shoot, ALL of modding an LS3 (or any engine for that matter) is just a series of trade offs. You get this, but you sacrifice that. On and on.

I'm actually in the same boat as you. My last two Vettes were supercharged and either would stomp the snot out of anything envisioned here. Don't want to go that route this time though. I'm wanting a simple mild cam and bolt ons rig.

Personally, I wouldn't pull off a perfectly good set of LS3 heads. They're pretty good as is. If I had to pull them off, I wouldn't go back with stock heads either though. Probably run them through Tx Speed's shop for a CNC porting and valve job.

For a cam, I'm going with a 226/234 114+3 with lift at .620 on both sides. I've had a similar cam and was happy with the power and manners. Will upgrade the rockers with the bushing style upgrade. If that's not enough cam for you , you can always increase the duration and still not get into high lift cam issues. If someone gave me a .650 lift cam, I'd use it for a trot line weight. No way would it find its way into one of my engines.

I'll add 1.875" long tubes, a rod modded intake mani, and maybe a ported throttle body. I'm calling it good at that point.

How much are you willing to spend to get that last few horsepower? The cost in $ and reliability just doesn't add up for me. If I wanted much more than a cam and bolt ons offered, I'd do another blower setup. With that you get MUCH more power with excellent reliability, good fuel eco, and perfect manners.

xBoostx

Why compromise?

There's always a way to do with out compromising "other" just that you must be willing to remove the limitations that bring compromise to the equation.

I milled my Trick flow heads and bought my choice llsr cam with all and 1.8 ratio rockers and "yes" it didn't work but had a pretty good idea what was needed and was ready to do the work. No compromise above using the stock ls3 block.

I fly cut the pistons .125 done.

The results? consistent 1.5 s/time 10.5 n-a A6 3400 stall.

Looking at the list of supercharged gs with stock block I do better than 60% of them a lot safer for the pistons, a lot simpler lighter and much easier car to work on and may I repeat? consistent.

No one need to school me on boost cause is what I do I made the 4 bolt heads and blocks into 6 bolts when there was no 6 bolt blocks or heads to be had, there again to remove limitations.

All the above to emphasize on the importance on any build however simple to do it with out compromising anything.

A little extra effort can put a big smile in your face every time you start that gem. Is a great sport enjoy it to the fullest.

Bigwebb

Looking more and more at the titan 3. I wonder how it would drive down at low rpms.

old motorhead

In a racing situation, you're only at low RPM just for an instant. If you're worried about buck, surge, and shake at low RPM, have that cam ground on a 115 LSA with another degree or two advance. That gets you a full 3* less overlap. That matters. Your higher compression ratio will cover up nicely for any perceived softness on the bottom end.

Bigwebb

Thanks man. I've been hearing that the bumped compression will help, but I only get subjective comments. Do you think that with a setup like this, my throttle response and low end power will be as good as they are now, way down low? for reference the car only has intake/exhaust/tune at the moment. I don't even have headers. So I think once everything else gets thrown at the car, it should definitely at least "maintain" down around 2k rpm. My main concern is being able to cruise at 1400ish rpms. And f'm reading mixed reviews on the feasibility of that, even with a moderate sized cam with 5-6 degrees overlap. Some people say that 1400 rpm with a 229/239ish cam is perfectly streetable, while others claim that a 227/239ish cam starts to get "moody" at 1800 rpm. I really don't want a car that jerks around at 1700-1800 rpm while trying to cruise. For me, 6th gear at 50 miles per hour is about 1300-1400 rpm I think.



Daniel

KW Baraka

Dan.....The cam in my DAILY DRIVEN, '95 Impala SS with stock cube LS3 is a Lingenfelter GT1-1.....229*/242*, 114* + 0 LSA. It has 7.5* overlap.

Unless your tuner is incompetent, a cam along these lines is what you want.

My transmission is a 4L60E and I have a 3000 stall TC. I get no surge and no bucking at low RPMs. On semi-rural roads, I'm on cruise control at 1500 RPMs......no huss, no fuss! Good low-RPM torque; but would be even better if the cam was advanced maybe 3*. Idle speed set at 800 RPMs. You can only tell it's cam'ed at stop lights; the lope is noticeable but not at all uncomfortable.

Look at more than JUST a cam's duration when you pick a 'performance' cam for streetability.....look at overlap! In the case of a stock cubic-inch LS3, I say anything equal to or LESS than 7* of overlap would be good-to-go!

KW

Navy Blue 210

^^^^^^^^^^Agreed!^^^^^^^^^^

Daniel,
The Cam you want is the Titan 3 with the exhaust reduced to 233-235*
So 227*/233-235* with 114*+3*. 3* Overlap, with a good tune
(at least) and 1 7/8" long tube headers, Rod Mod Ported LS3 Intake,
~11.0:1 Comp, should make 400 LB' @ 3000 RPM & Exceed
500 RWHP between 6200-6500 RPM before starting to roll @ 6800.
on a legitimate DynoJet.

If you look at Jaybee final build and results (which were very
good BTW) he had 375 lb' @ 3000 & 494RWHP @ 6200, before
rolling off hard @ 6500.

I know one shouldn't compare dyne results & flow bench #s
other then for base line comparisons on the same equipment.
But the truth is most of us do, and we can learn from others
builds and plan accordingly.

The big differences are in the Heads, Your TFS Heads with a
12-15 CC Smaller Port size Flow 6-12 More CFM from
.400-.600" That means your 227*Duration & .621" Lift
Intake Cam will flow more total Air Vs 230* & .604",
with much higher velocity,
Thereby being MUCH LESS Sensitive to Overlap.

The MUCH BIGGER DIFFERENCE is on the Exhaust Side!
The TFS Heads flow +17,+29, & +24 CFM @ .400,.500,&.600"
E/I Ratio 73%,72%,& 69% VS 70%,65%, & 65% and those are good
TSP PRC Ported OE LS3 Heads. Factory goes from 65%-60%
even worse. So Why use a cam originally designed for the OE
Heads with poor E/I Ratio and 10-12*, or even larger Exhaust Splits?

Bottom Line a +6*-8* Exhaust split will allow you to have GREAT
Daily Driving Manners with Wicked Throttle Response and
STILL Peak 6200-6500 and carry to 6800.

Its the Heads, Its the Heads, Its the Heads! LOL

"Have your cake and eat it too."


Daniel Also

old motorhead

I'm 100% sure that the 226/234 114+3 cam that I'm going with is going to be exactly what will make me happy. I've had almost that exact same cam and was pleased. We're not trying to make me happy here though. With you upping the static CR a bit, it may not be optimum for your build. Why not invest $40 and bring Pat G into the equation. He's been there, done that, X100. Even if you don't use the cam he recommends, it will be good to get his opinion on things. Settle on exactly what you're doing to the heads and fill out his cam rec sheet. That $40 may be the best bang for your buck that you'll spend on this build.

Bigwebb

paypal sent and form filled out last week. Anxiously waiting to see what he has to say, as he appears to be very well respected around here. As you said, I may or may not go with that cam, but it will be good to see his opinion compared to what I'm narrowing down to in my head.


Daniel

Bigwebb

Wow, that's ultra helpful. What you're describing is exactly what I'm looking for. Is the reduced exhaust duration something that would trade a tiny bit up top and replace it down at the bottom essentially?

Somewhere I heard that a larger exhaust duration makes it "a little hotter on the top end" and a reduced exhaust duration makes it "a little hotter out of the corners"


Daniel

Navy Blue 210

Yes..... but the specs are most influenced by the
Exhaust/Intake Ratio of the Cylinder Heads.
~60% +10-16*
~70% + 8-12*
~80% + 0-6*
Thats just spitballing and for NA.
The closer to ~75-80% the closer to a single
pattern cam profile, depending on RPM (range & application)
Compression, and the rest of your combo, inlet to tail pipe.

I Agree with getting Pat Gs input, $40.00 very well spent.

Again not an expert just my .02

Bigwebb

so I just found out that the stainless works headers I bought from a forum member, that I thought were 1 7/8 are actually 1 3/4. I know there is some debate about how much this matters on a naturally aspirated application, and even some people that say 1.75 may offer more throttle response and low end while sacrificing virtually nothing up top.

My question is, in this case, with throwing everything I can at this to make it an air pumping machine, am I going to notice/feel/regret 1.75" headers? My gut is saying it's perfectly fine, but wanted to get some feedback.

Navy Blue 210

My opinion,
As long as you have a good X pipe and everything after you won't
See or feel a difference. Tony's first 454" LS "Darth Vader"
~700 @ Flywheel only made 8 more with 1 7/8" VS 1 3/4" IIRC.

@~620 Flywheel, -6 at most..., + maybe a little more torque
Idle to 3000 RPM .....maybe.

Definitely +8* VS +6* LOL.

KW Baraka

For the very small extra cost of 1 7/8", they would be a preferred purchase. BUT.....the 1 3/4" headers won't hurt you much at all.

Bottom line.....you got 'em.....use 'em!

And if you ever meet the seller down the line.....deal with him at that point; but don't sweat it for right now!

KW

Bigwebb

yeah, just a mix up, but I think the mid range will benefit from the 1.75" over the slightly larger anyway. I'm not terribly concerned with 2-3 horsepower on the top end.

jstewart

My 08 LS3 uses AFE ported/Trick Flow 255 heads. I have used the stock rockers with Trunion upgrade for 4 years with no problems. The cam is Spins 230/234 which has been in the car since 2010. Block & rotating assembly is all stock. With Fast intake, ported TB and other common upgrades the car makes 530 RWHP. Unless I put a lot more cam in car I see no need to go to aftermarket rockers.

Bigwebb

If the cam you are speaking of here is much less sensitive to overlap, would it make sense to go with a 113LSA? That would put me right at 5 degrees of overlap, if I go with the 227/235, or 4 degrees if I went with the 227/233. Am I correct in thinking that the lower exhaust duration should correlate to more low end and mid range? Would the 233 start to fall off more quickly after 6500rpm?




Thanks,


Daniel

Bigwebb

Nice man! How many miles do you have on the setup? Wondering if you've changed springs or anything yet. I think his cam is supposed to be reasonable on the valve train. Did you mill your heads?

Bigwebb

how is the wear on the springs with 1.8 ratio rockers vs 1.7? My understanding is that I'll have to upgrade the springs that came in the TFS 255 heads, but I'm more concerned about whether or not this will cause me to have to refresh the heads (springs) more frequently. I was told I should be able to go 25,000 miles between spring changes. I don't love that, but I'm willing to live with it. Anything more frequent than that is going to be a turn off for me.


Daniel

KW Baraka

Daniel......cams are not sensitive to overlap, the cam (specs) is what creates the overlap.

As far as exhaust duration goes, the amout of duration determines how well your air-pump....urr....uhh....I mean your engine is able to exhale.

More exhaust duration will create more overlap, but it will also aid your engine as it carries power into the higher RPM range.

In other words, the 227*/235* cam and the 227*/233* will have about the same low end and midrange....but the 227"/335* should carry a bit more power up top and should give you a few more RPMs up top as well.

With your power goals, I would go with at least 240" on the exhaust lobes.

A higher ratio rocker arm increase the lift of your cam lobes. My cam (229*/242*) is spec'ed at .631" lift with 1.7 rockers.

With the 1.8 rockers that I have, my lift increases to .667".

As a result, I use springs rated to .700".

The benefit for me is that my heads flow more air at .667" lift than at .631" lift. So the 1.8 rockers allow me to tap in to that additional airflow and as a result.......helps my engine generate an additional 10-15 whp.

KW