You're exactly right 😉 I put together a few turds myself before I figured all that out lol

 

Thanks for all the feedback.

I am working with TexasSpeed. They're great and helpful. We will eventually figure something out.

I have to plug it up with mediocre exchaust unfortunately, We cant have any visible mods out here,

I dont have a professional tune yet, I got the MAF and VE dialed in reasonably well on LTFT's as i didnt get my wideband till just now. Its being installed today. Im going to be working with someone online who knows his stuff so should be able to get tune issues slquared away.
:
Good idea Ron about the TC lockup. believe it or not that very same idea occurred to me this morning. But If i change that and it works for the dead spots. Hell yes.

I havent as yet done anything with the Torquemgnt in the tune . but will work on that.


Heres the atest tune and a log.

The log isnt from exactly this tune, but on the log in the area of
19:49 youll see where in fourth theres throttle movement from around 1200 rpm and very sluggish rpm change.. also in the same area same thing around 2000 rpm...
I think Rons Right.. TC Locking... will look see..

 

Im in switzerland, We have decent high octane fuel, but very restrictive Regulations. Regular inspections , Cant have anything that they'd notice is not stock. Only approved add ons. I could get away with a look alike intake, like an LS6 or one of the generic looking fast ones.
And could eventually do headers, if I swap them out every two years for inspection.

These will be things to consider for me . If i cant get my decent low end driveability largely back with this combo as it is plus a decent tune.

 

Everyone's already told you what needs to be done. You have very very tall gearing and a tight torque converter and very big ports on your cylinder heads so your engine is stuck all the time in a range it no longer works very well in. You either need to change the camshaft and the cylinder heads or you can leave the camshaft in it and put some small chamber small port truck heads on it 706/862 and have a fun to drive combo with the tall gearing and the tight torque converter or you can leave the engine as it is and replace the torque converter and the gearing or just do gearing none of these things will make the car look any different but it will perform much better You don't have to put headers on it

 

That cam and heads should be just fine with a proper tune

Corvette exhaust is generally pretty good so even though you can't change it, it should be enough for the car to run decent. Although I would do anything I could like straight through mufflers and gutting or deleting the cats and then tuning out the rear 02 sensors so that an inspection machine won't pickup that there are no cats

Stall converter will help, and will make the car a whole lot faster

Before you do anything. Get a proper tune and then evaluate

Really bad low end after a cam swap usually indicates the cam timing is retarded, but we can't really judge anything until a full proper tune is done on it.

 

Beware when a thread is stale for this long there's probably a crappy car for sale with no low end lol

 

Not to worry... it's in Switzerland.

 

Lol lol.. No no. No crappy car for sale... Been going through the tuning process..
​​​​​​As I got a wideband finally.
1. Turns out my ltft tune was not bad. The low end is a big bunch of minuses in volumetric efficiency.
2.it never gets into plusses, but is no longer minuses after about 3500
3. While working on the tune my Harmonic Balancer has worked its way loose.
Crap!!
4. I'm having a guy who knows ls's put in the HB and will have him put in a new cam at the same time. Deciding on the correct cam profile.
5. The ideas :
Texas speed said 212 218 114. 600
My guy is saying he had good experience with similar sized dart heads with:
220 220 115. 560
Or 216 221 116. 560

Hes going to do the work and Will degree it. But won't be able to do it till end of May so I have time to figure out and choose the cam that'll give me the decent overall characteristics I want.
That's where I'm at.

 

Still would drive better with a converter even with a smaller cam.

 

Can you at least throw some LS7 manifolds and midpipes on the thing?

 

Even if you put a smaller aftermarket cam in it with those heads on it it's still going to have crappier low end than stock because you have a stock torque converter and 2.73 gears see my post above where I talked about port velocity a little bit This is LS1 tech anyway The best combo for a stock torque converter and 2.73 gears with heads with big *** ports on them like that is probably going to want the stock camshaft back in it to keep any low end at all You need a really early intake valve close point no matter what the compression or anything else with those tall gears and stock converter.

again, if you have stock cubic inches of 346 and You want to keep the stock torque converter in 273 gears and improve engine performance across the entire RPM range you should leave the stock camshaft in it and install a set of 706 heads for the most low end you can mill them and get even more compression for more low end or you can do 243 heads with the bigger intake valve which is the same size as yours already on the stock heads and you can mill those for more compression and have a little bit more horsepower up top and pretty good low end as well but the ports on those are bigger than the stock 5/7 heads and so those lose low end as well

 

Just to throw this out there... a good stall converter will make the car faster than any cam will. A small cam will make a small change, a big cam will make the car slower if using a stock stall. So never skip the stall if your goal is to go faster with an auto.

A stall should be the #1 item on a modded auto's parts list. Possibly debatable if you're gonna put a positive displacement blower on it.

 

All the tuning in the world won't fix needing a stall .

 

Maybe because I'm in California I have it easier to make my '01 Z28 quicker because we have strict emissions requirements I have to keep in mind that I must be careful to mod wisely. I made one change at a time. 1st I upgraded to 2.5" y-pipe. Swapped from the stock 241s to a pair of 799s to the current 243s that I ported. My car runs strong for a mildly modded Camaro. Maybe swap out that cam and start with a simpler setup.

 

People always talk about and ignore torque converters in threads like this it's very annoying for people like me who are trying to emphasize the importance of dynamic compression and port volume and such in a low RPM application, You can still have a fairly aggressive cam timing with all that and a tight *** torque converter or even low gears sometimes if you can get most of it right. Op, and everyone else who doesn't understand the stall converter drive any 4-cylinder vehicle with an automatic transmission power break it look how much higher the engine is allowed to rev then your V8 automatic That's because the transmission wants to let that little engine spin up where it makes power That's all everyone is suggesting you do to your transmission by adding a looser torque converter that's all it does it makes it more like a 4-cylinder's transmission where it lets the engine spin up a little bit where it makes better power since you want to add aggressive cam timing or cylinder heads with big ports that work better at high RPM then lower RPM You need such a compromise or you need more compression there's always a trade-off I'm not going to keep rambling all day long I have better things to do but I do love this s*** so enjoy and thank you I hope somebody gets something out of my rambling

 

Sell the heads, sell the cam, and install the stock heads, cam, and tune. You have a bad combo that's going to kill your desire to drive your C5. Then do research to learn what you need and $2500 heads are not needed. Start over.

 

Sorry Dave, but if I could downvote you I would.

Even with changes in dynamic compression every engine has what is basically a hard floor of how much torque it will make. The solution is not to sell his parts for pennies on the dollar. With a tune and some street-ability minded changes like torque converter and gears this car will be a joy.

 

Kawboom, I found his thread on the Corvette forum and they all suggest similar things such as swap the cam/heads/gears/converter. Remember though that he is in Switzerland so there may not be anyone who can tune his C5. He would have to learn to tune himself. It's possible since I did minor mods to the tune on my '01 Camaro.

 

This combo is nothing new I'd wager it can be tuned mail order no problem. Just throw some converter in it, 4.10s and call it good. These things are basically required. You wanna play you pay. Touch one thing and you have to upgrade 4 other things. It's the way of the sport.

 

We need to be talking acceleration goals here more and horsepower less. A 400 hp auto LS car with a stall will absolutely murder a 400 hp auto LS car with a stock stall.

Thing is a good converter with no other mods will make an auto f body faster than any mods discussed in here. Some guys are in here talking about super strict emissions and talking all about cams etc and not talking at all about converters, tires, suspension, weight reduction..... Some of the biggest and by far most important things that help these cars go faster that have ZERO chance of getting you into trouble with emissions.

You can do emission legal bolt ons, stall, weight reduction and tires and tune, and blow any size cam, no stall having, little or no bolt on f body completely off any road any time.

Stalls allow the engine to operate in their power band, and THEY MULTIPLY TORQUE and create shift extension, those things are major game changers. Especially with a 4 speed trans with big ratio changes between gears and a long first gear.