The lift is what kills springs. It isn't clear how much you plan to drive this thing. If it's a race car, no problem. If it going to see street time, you want to stay in the 0.600" range or so unless you enjoy checking and changing valve springs. You will need GOOD (= expensive) springs as well as lots of them.

Are we talking about a pure race car? If so, then I have no problem with the cam specs. But it will not be a street friendly valve train.

Ricgh

 

I just watched a vette dyno 440rwhp yesterday with a 383SR and LT4 heads from AI. It was pretty impressive, I also found out that there is no black death at 7200rpm, its basically a rev limiter that cuts fuel off.

 

Yea, well what about the 2012 thing and the Mayan calendar?

 

And what kind of rpm are those circle track cars running?? With a 102 lobe separation the cam isn't streetable at all. You know that. If it's a pure race car towed on a trailer, no problems, but a car that sees the street. No way.

All I'll say is good for you and good for them but mine goes through springs with .630 lift and a moderate Comp grind. Not so sure about the last batch as I need to have them tested as I had other issues like a leaking intake that may be the real culprit mimicking what bad springs look like. New ones are in but not quite ready to throw them away until the fat lady has her final say. Didn't know for sure about the intake leak until this afternoon so it may be a false alarm or maybe not.

 

This is FYI at this point, since I think we're all pretty much on the same page. The SUPR motors make peak power at around 7200 rpm. Streetable? Not at all. But it would turn some heads at the local Sonic. However, for a max effort small block, it'll make power. They also use a 4/7 and 2/3 swap, and were doing it way before Comp introduced them for public consumption. Funny thing is, the rule book states they have to use a stock firing order. They are using a stock firing order. . . for an LSx.

Mike

 

I apologize, let me be more specific, no the car is not a pure race car. I will drive it on the street on a occation, local cruz-ins etc. I see maybee I was wrong about the lift thing, maybee it is too much for a street driven car?. Not a problem, I guess im trying to have my cake and eat it too. Meaning, having a radical setup and being able to drive it on the street as well. Am I asking too much or just being greedy?

 

Probably something else I should mention regarding the springs not lasting with .630 lift is also normally shift the car around 7000 rpm and when I'm trying harder, it gets shifted @ 7200 rpm. The rpm range is also probably a little harder on springs than most. RPM kills springs.

The car makes a little over 480 rwhp peaking around 6600 rpm but makes 470 rwhp at both 6000 rpm and 7000 so it very flat on top. The reason I point this out is it's 398ci with a 245/248 cam and 222cc intakes on the heads. Guess that's why I have to question a 250/260 cam in a smaller 355 as the peak power point would be sky high not counting drivability issues. Unless geared right, it would be a real dog on the street. A stock computer (I have a LT4) is only good for 7000 rpm and that's another factor.

Frankly I'd do as I say and not as I do.......don't reinvent the wheel. Just go with a proven combo instead of being a space monkey shot out into outter space as you may not come back. Lot's of good proven combo's you can copy and save yourself some grief.

 

The circle track guys don't get the respect they deserve. Pretty inventive group and my rotating assembly comes directly from talking with a few. Instead of going with the biggest brand name for bragging rights, went with what works as these guys have it down to a fine science.

 

No problem. I understood what you were getting at which is why I told you to go more conservative on the cam selection than what's been talked about. Engineermike, rskrause, and others know their stuff (more than I do), but there was just a misunderstanding. Listen to them.

I still stand behind my last post. Since you want street time too, shoot for a cam in the high 230 range duration, near .600" of lift or a little less, and 110-112LSA, preferably 110LSA so as to not bleed of as much cylinder pressure. Grind it on Comp XE or even XER lobes. Steeper ramp rates = more power with broader powerband and more engine vacuum. The cost is you'll need some tough springs to handle it.

An important thing to consider is to get as much quench or "squeeze effect" as you can with the combustion chamber. Shaving the block to get the pistons to sit higher in the bore (ie: zero decking the block) and running a thinner head gasket both do this. A tighter quench not only adds compression, but also increases resistance to detonation and creates a more efficient burn, = more power. The only thing to watch out for is P/V clearance, but a piston with generous valve reliefs takes care of that.

I recommend you get TEA Stage 3 LT1 heads built off Trickflow castings. They flow close to 300cfm with 200cc ports and have a bigger 62cc chamber than stock heads. An LT4 manifold would help too. Run .040" head gaskets and zero-deck the block for a good quench. With flattop pistons you will be right at 12:1 compression (12.042:1 by my comp. calculator). IMO this will be the best "have your cake and eat it to" combo for pump gas, decent valve spring life, and great streetability with a dyno tune. You may get maybe 15more hp with a radical cam, but attention to detail and carefully matched parts will get you very close. Shiftpoints would be close to 7000. I would expect ~450rwhp with supporting bolt ons. This is all for a 383.

If I missed some things, I'm sure the experts will chime in.

Jason

 

I ran isky springs(forget part number) for 5 years on my car. Beat the ever living crap out of it and when I changed heads the springs tested to brand new specs. My lift was over 656 intake and 628 exhaust. Shifted at 7000 with stock pcm and 7400 with DFI gen 7. Somewhere in that time before they just got replaced I went to 1.6 RR shaft mount rockers and lift was right 69x/65x. Everything held up great. It wasn't a full time street car...and as time went on it got more and more where I only used it at the track. But when i first built it I would drive it all over the state to go racing and out to cruise nights.

 

I dont quite remember what your cam specs were but how was the driveability(not that I care). Mainly, did you have brakes?.....im getting so many different answers on this subject. Dont get me wrong Im absorbing all this like a sponge and I appreciate EVERYBODY's advise. I think the best thing for me to do is look at and ask the people with these combos what has held up and worked for them. But my main question was answered, I am going stroker. Thanks guys for not turning this into a three page argument. greatly appriciate it.

 

It was streetable but not by any means a daily driver. Of course I will put up with alot. It surged below 1800 rpms...had to give room at a light then "launch" the car..but that was more my on/off switch spec clutch than the cam. When i first built it I took it on a pretty good trip and got around 21 mpg on it. Specs with the 1.6 rr were 694/656 255/263 @ 50 on a 110 LS.

 

You are really not reinventing the wheel here. If you plan to use Lloyd's LE3 heads, perhaps you should consult him on the rest of the package you need to reach your goals. 355 vs 383, SR vs HR, etc. You might be surprised.

To get 130 you might consider a serious weight reduction program for your car. That should help ET also...even if you don't care about being quick.

 

I hear what youe saying and I wil Ask Lloyd when i have time. As far as the trap speed...lol. I say that b/c usually if your in that range espcially with a m6 you have the potensial for 10's.

 

Javier isn't far from the 10s, but he's below 120. That next 10 mph needs a LOT more power.

http://web.camaross.com/forums/showthread.php?t=509880

No offense, but your plan sounds a little like an MLK car.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
MLK = Martin Luther King: "I have a dream."