I put psi 1511 springs on my ls6. They seemed to work well. My shift **** came lose and i did the dreaded 3-2 shift one night. It took it with out even a hiccup. I do hope that doesn't happen again.

 

Yeah valve train must be right.
Have had luck with both pac and psi. Talk to them directly about what spring to run. Manton and Jesel for pushrods.
Ill look up a part number for valves spring and pm you.

 

Have you talked with BTR? I believe Brian has done extensive spin tron testing proving the Beehives have little to no advantage over his dual platinum spring.

 

.
I've tried all kinds of funky gear changes, even the 2-1.
That stuff will make for a bad month.

A solution: If you can run a shifter like the Hurst that has centering springs you increase the spring pressure with stronger springs or doubling them up. Then another trick is to bias the spring pressure toward the passenger side with unequal Springs. This way things want to go toward the higher gear. It also works for racers who miss 3rd a lot because the hit the gate between 1 and 3.
Test it out plenty on the street before racing.

 

No I haven't, I know hes got good springs and it may not be worth the switch after I get the right valves back in the heads. I had it to 7200 last year but it didn't seem like it pulled that great up there so I set it back down to 6800. I need to get it on a dyno this year and see what the power curve is honestly. Im putting a msd and 102 tb on and will probably put a gz vacuum pump on. Ive tried to refine the chassis as well with some lighter stuff like drag brakes and lighter clutch assembly.

I juss have that katech spintron test in the back of my mind, I feel the ls7 is alot more tricky to set up bc the big valves and and people always jump to the stainless exhaust valve. Kills me that rob vette will eat up any ls7 I can think off. I want this thing right and running how it should.

 

YES...


Christian

 

I did not see the other post you refer to, can you provide a link please?

 

Posted by robz on Corvette Forum:

Heres some info I posted in another thread that may benefit some of you drag racers by helping establish shift points. There are huge gains to be had if you get this right. Do your PUC calculations and that will get you in the ballpark, then fine tune at the track. A g-meter is one of the best tools to confirm that your putting the power to the ground. If you are confident you have the max power under the curve at the rpm band you will be racing in and don't see much gains in et and mph then you need to optimize your setup for the drag strip and a g-meter can tell you this. The most common cause of this is excessive wheelspin.


Just to drive the point home about power under the curve here's another example for anyone who wants additional info.





This particular dyno pull stops at 7300rpms.
Use all your resources to predict what the car does beyond the dyno max rpm if you don't want to pull any higher.
Assuming this is a well designed and sorted out setup I drew in pencil the estimated power curve beyond 7300rpms up to 8000+ as one possible scenario. (Of course you need have some reliable data and experience to do such an estimation. Some setups drop off hard after 7000rpms due to instability. This one doesn't.)
Now find out how much your car drops in rpm in each gear on the drag strip.

To keep it simple and "on the lines" let's use 1900rpms.

Without even doing the math you can easily see that if you shifted @ 6920rpms (which some people feel is high) you would be giving up a huge amount of power throughout the entire gear.
6920rpms would fall back to 5020rpms and the hp at that recovery rpm is low.

Now pick 8060rpms as a potential shift point. The rpm falls back to 6160rpms. Look how much power under the curve is in this range. We are talking about a difference of an average of ~ 40whp throughout the entire pass. I would say you could be losing several tenths in et if you are shifting @ 6800 vs 8000 rpms in this case. And for those who are infatuated with torque you can also see how the shift recovery rpm is droping back still very close to peak torque, so perhaps an added bonus.
This is the game you must play if you want to run low et's and high mph. This car should be shifted above 8000rpms for maximum potential hp. And if you want to get even more detailed you can do the calculation for each gear and shift according in each individual gear with a variable shift light. Making the power is only part of the equation. Knowing how to apply it to the drag strip is equally as important. Then finally being able to put it to the ground is the final piece of the puzzle.

And of course the entire setup needs to be designed to handle the rpm you plan to race at without exception.
It's also of paramount importance that anything you estimate must be based on a large population of accurate data for all this to work.
Hope this helps.

 

There's a great article in the link below that will answer a few questions asked here regarding lifters, springs, valve size. Obviously the engine in the article is LS7 but information on valvetrain applies to all because the LS7 has 2.2 intakes and any valves discussed in this thread will be smaller limited to bore size.

A quote from below article;

""....while the bulk of the hot rodding world is perfectly content settling for the first 90 percent, only the smartest guys in the room can find the next five percent. The quest to find the last five percent, however, goes down in top secret assembly rooms that exist entirely off the grid....""

http://www.chevyhardcore.com/tech-st...eliminator-ls7

 

Certainly apples and oranges here but they both are fruit and grow on trees.

Watch the video and read the article in the link below describing known design advantages that Mercedes engineered within the rules to dominate F1 in 2014-2015.

http://www.enginelabs.com/news/video...s-f1-dominance

 

Rob,

I spent much of my Saturday reading your threads here and on the Corvette forum. I think you're pointing out some hidden advantages to a short stroke, small bore, ss/sb engine. I'm no expert but here are my initial thoughts/possibilities.

1. Plastic intake doesn't hold the ss/sb engine back like it would a big cube engine.

2. Valve train stability at high rpm is easier to maintain with smaller diameter, lighter valves.

3. Your heads will only need 300-325 cfm to achieve your hp goals. Estimated 650fwhp for 575rwhp with a cfm multiplier of 2 to 2.2.

4. Your hp per ci is 1.87. If 650fwhp is correct.

I recently did a short stroke bbc that is currently at 1.7hp per ci. We stopped the dyno pull at 7000. When I get the efi set up installed we'll go to 7500 and I'll be at 1.8. This is a 4.5 x 3.75 engine, 477ci. At 7000, it made 810/669. The same top end placed on a more common bbc 540 would have made 1.5hp per ci. The difference is the 540 would have hit the number at 6000.

Summary opinion. Any top end that supports 650fwhp and fits on the 3.898 bore will get you to 575rwhp. On a 402/408 hp would be around 6000, on the 346 7000++. I hope you get bored and build it.

 

No doubt.

1. Especially if you are only buzzing to 7k or slightly over and it's much easier on a vette to use a manifold that bolts right on. Plus with the SBE you have rpm limits and that's why plastic intake and hydraulic roller don't hurt much

2. And don't stop at valves, make everything lighter and smaller.

3. Any good head could achieve that.

4. I've done the math with rwhp and fwhp based on dyno numbers, track et's, data logs , and other input and it all tells me it's plausible.
Thanks for the input. I'm hoping people take advantage of this stuff and challenge themselves to make better performing setups.

Why can't a lightweight SBE 346 set for the drag strip see low nines? Maybe cause people don't believe it.
Give me another 55 hp and I'll find 3 tenths.

 

I went thru similar skepticism with my baby bbc. I wanted hp but didn't want the tq to go with it. I was hoping the shorter stroke would produce lower tq. When we got the engine together I asked the builder what he thought it would make on the dyno. He said he didn't know if it will make 650 or 850 lol. I think it will eventually make 850 at 7500. The engine is going in a 68 c3 l88 style of car. I have to finish my 65 c2 sbc 427 first. The sbc is running an itb like your 388.

The last car on my bucket list will be a built c6 z06.

 

Sounds good. We are playing around with an n/a c6Z right now.

 

That's cool. A buddy back in my highschool days built a replica l88 and put it in a 70 z28. Kinda what we would consider bolt on these days. But it even had a stock production l88 intake on it. That car went 10.6
Sweet...love some c6z. I have a ls7 rebuilt to stock but wet sump and 24t reluctor for my camaro if i ever get done playing with the ls6.

 

Have any good secrets on that n/a c6z lol?

 

I was thinking the same thing.

 

What's your definition of a stock bottom end? So your saying I could get a wrecking yard 346 and make 500+ HP with it.

I've looked over several years of engine master builds and those guys aren't making the kind of power your talking about with those heads and cubic inches.

The ET's you have run with your builds are very impressive. If everything else on the car is optimized you can run good ET's with less power. Several of the other posters show that.

I'm not drinking the kool aid just yet. If you have this figured out then you should be building engines for the NHRA stock classes and making some $$$, or better yet step up and run those classes.

So not to be a true Richard head and just bash people. I give you a lot of credit for going as far as you have and pushing the boundries. I certainly have not with my builds. Good luck with your quest.

 

YES, and I'm referring to SBE as stock rods, pistons, crank, etc and all the same stock parts(big and small) that comes from the factory for the 346.

I added rod bolts for safety since we are spinning the motor.

I don't have the education or the skill to be building motors for anyone but will admit that I do think like a pro-stock racer when it comes to my drag racing hobby.

 

We do a lot of the same things with the c6Z that we did with the c5Z to make power and to perform well on the drag strip.

Some of the fastest c6's that I help with all take advantage of high rpm and lightweight stuff.


Here 's one way to make power in a C6Z.

https://ls1tech.com/forums/dynamomet...935fwhp-n.html

This setup was originally designed for my car @ 10,000+ rpms but it has found a new home in a C6Z and at a more conservative atmosphere.
A 396ci pushing 1000fwhp in my vette.... One can only dream.