Cam is solid, 640 lift, 236/236, 112 lsa. Valves are 2.08/1.60 in a LS6 head. T&D shaft rockers, dual springs, Flycut pistons 100/1000ths. LS6 intake, 30#svo injectors, TPIS headers, Vararam. FLP-4 tranny.I run a 3:73 gear with a PI 3800 stall. Dynoed 390 rwhp at TEA last week and ran 11:70's at 117mph all night with a 1.70 60 ft. I should be running at least 11:30's. What could be the problem? My programming was done at TEA and seems fine, I do have LS1-edit. I've been told I have to much lift and my valves are too big for a stock bottom end. Anyone have any insite?
(Edited-bad fuel pump) thanks

David

 

Do you have any flow numbers on the heads? That lift does seem high, I think the LS6 intake would be huge bottleneck in a combo like that. Do you have a dyno graph you could post?

 

I've been told I have to much lift and my valves are too big for a stock bottom end. Anyone have any insite? thanks

i would say that is a true statement. everything have to match. your heads should be able to flow at least 320+ inorder for that cam to work properly and i would say atleast go with an all bore motor for best results.

 

ARE never sent the flowsheet on the heads, but said they flowed 320. I've been offered a deal on a 427 block and crank from a friend, I just want to figure out what Nic at ARE was thinking when he suggested this package for me to begin with. You would think a $6200 solid roller H/C package would have more hp than this.

 

gomer, I'm still waiting on the dynograph from total Engine Airflow from last week, but the graph show me making power (390rwhp) to about 6700 and leveling out, but not falling off, even past 7100rpm.

 

You're on a (shudder) stock bottom end?

Did you guys check PtoV?

My cam's only slightly bigger (242/242 .65/.65 114), and with the slightly goofy heads I have (they got over-machined along the way), I put down 442 (with 2.02" valve, and less than 320 cfm flow). So yeah, I'd think that your valves are too big for a 346 (velocity is down), and you may have P-V issues.

Have you done a compression check to see if you've ever tapped the valves to the pistons? If you've got slightly bent valves, the motor will still run, but it'll tend to be weaker. A compression check will show this.

-Andrew (edit: RTFP )

 

You need to have your heads flowed up to .650 lift to see how they do. Make sure this is done on a stock size test bore, to get accurate numbers with your valve size relative to bore diameter.

3800 stall is somewhat mild for a solid roller setup. Most guys running solids are in the 4500 rpm range on stalls.

LS6 intake should be borderline acceptable for a stock cube SR setup. I don't see that as your main problem.

Any dyno graphs to post? How does that higher rpm range look? What are your shift points?

Tony

 

After you get you're power sorted out (and you're way off for a solid lift heads/cam package, IMO), you really need more gearing and especially, more converter to fully take advantage of that high revving cam.

I'm willing to bet that your heads don't flow 320.

 

I, ummm...bought almost that same package.

"Good luck with that".

The head exhaust ports flowed very poorly, and there were a number of other issues.

In my current setup the only thing left form that whole fiasco is the actual head castings. They have been re-ported of course for huge flow gains.

chris

 

im with andrew on this one, and 390 HP is WAAAY low for a solid setup. something isint right. either it's cyllinder pressure (bent valves, HG, rings) or it's the heads themselves. i'd definately get them flow checked. whats your CR, timing, and AFR? whats your lash set at? i'd hope that it's up there, but at those numbers, something's definately off to the tune of 50-60 HP.

 

screamin...
PM a member by the name of IMKMFAST and ask him what his ARE Stage III heads off his 422 motor flowed when he took them to an independent bench.. I saw the numbers and the heads, but he has the exact figures.

 

*cough*

 

Those were my Nick-Gen LS6 Stage 3 LS6 heads wiht 2.08 valves before and after MTI's work on them.

 

Thanks for all the replies. Now for an update. We Autotaped the car tonite and I'm still going through the #'s. However, we hooked up a fuel pressure gauge, and fuel pressure drops to 25psi under load at about 6500rpm. Now that really sucks! I had noticed at the track once I got in 3rd it seemed to fall on it's face. I remember looking down to see if someone cut my ignition off!!!-haha
Why can't this be evident on a dyno? Wouldn't my fuel ratio show a fall or something? I don't see why this got missed. Anyway, I'm borrowing a slightly used stock one for the track thursday, and shopping for an upgrade.

 

"and fuel pressure drops to 25psi under load at about 6500rpm."

NOT GOOD!!!

You're under more of a load when not on the dyno...that makes a diff but it shouldn't make that much of a diff.

 

That's probably your problem.

Fix the fuel system. If your WOT fuel pressure drops more than 10 psi from base (58) then you will lose power.

Make sure also to try different shift points to find where the car should be shifted.

I'd try 6400 for both shifts and go from there.

I like to keep an eye on the 1/8th readings, you want to be going 98 mph or faster IMO for the parts you have. Anything in the 7.20 or less range is nice.

 

Installing a newer stock pump now, and ordering LPE's. My 1/8th averaged 7.49 at 93mph. Here's my best slip #'s on motor:
R/T .055
60' 1.707
330 4.868
1/8 7.496
mph 93.04
1000 9.780
1/4 11.701
mph 117.54

 

was the 390 locked or unlocked? 390 unlocked through an A4 is a bit low not not as bad as it looks although your mph isn't great for a vette. what was the DA?

More stall would definitely help in the ET dept.

 

I bet the fuel system and a retune will help.

Be sure to always run a FP gauge when tuning so you can watch the pressure.

I think you should be running 98+ in the 1/8th as well. I am a hyd/2.02/1.57 valved setup and went 7.1@98.8mph in the 1/8th at 35XX pounds raceweight. (I am 360ci though)

Cheers,
Chris

 

ScreaminDemon classy move editing your thread.Good to see you found the problem and it was'nt engine related.Please post your track results after the fix.I have a nagging thought about a solid-roller LS6.