Valvetrain aside, what do I need to do to safely spin to 7k RPM on a stock bottom end? Double roller timing chain or LS2 timing chain? What else? Thanks.
Reliably? I would say a balanced and blueprinted forged rotating assy.
Ok, how about "somewhat reliably"?
Seriously, I don't want to dump a ton of cash into this motor - I'd rather save it towards a C5R 427. The heads/cam setup I'm looking at is designed to spin up to 7500 so hoping I can go 7k without problems.
Seriously, I don't want to dump a ton of cash into this motor - I'd rather save it towards a C5R 427. The heads/cam setup I'm looking at is designed to spin up to 7500 so hoping I can go 7k without problems.
I'm not an expert but, from everything I've read you're biggest concern at 7000 rpm will be your valve train, valve float, P to V clearance, etc.. Keep it tight and you shouldn't have any problems. I wouldn't spin it faster than that.
I'm not an expert but, from everything I've read you're biggest concern at 7000 rpm will be your valve train, valve float, P to V clearance, etc.. Keep it tight and you shouldn't have any problems. I wouldn't spin it faster than that.
Along with that remember Subdriver's post about his timing chain problems. That to me would be my biggest concern.
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Never argue with an idiot. They drag you down to their level then beat you with experience.
You need to look no further than the specs for the new LS7. As a minimum on an LS6 I would replace the OEM main caps with KaTech Billet Main Caps and the rod bolts with KaTech or ARP rod bolts. And since the engine is apart I would Blueprint and Balance the engine.
I would also consider:
- A gun drilled and aero leading edge forged crank
- Katech, Oliver or Carillo Rods
- Forged Pistons from Ross, Weisco, JE etc.
- Porting, Polishing and reshimming the Oil Pump
However the major impediment to spinning 7,000 RPM is in the valve train.
There is a good article in the March 2005 Corvette Fever, pp. 54-61, "Valvetrain Variations" as a reference.
My recommendations at the very least would be:
- Double Roller Timing Chain OR
- Chevy HD Timing Chain, Part # 88958608 and Timing Chain Damper Part # 88958607 (This is a single roller but has thicker sideplates) OR
- You could also consider a Jesel Belt Drive
You should stregthen and lighten the valvetrain with stronger:
- Roller Tip Rocker Arms (Comp Cams Pro Magnum)
- Push Rods
- Rocker Studs
- Push Rod Guide Plates
- Dual Valve Springs, possibly larger dia.
- Titanium Retainers
- Hydraulic Roller Tappets
You should also consider installing shaft mount rocker arms either from Jesel (J2K), T&D or Comp Cams
Another area frequently overlooked is the OEM plastic Lifter Retainer Box. You should seriously consider a Billet REV Kit from ARE. You can also drill 1/2" holes in the lower face of the Lifter Retainers to provide better oil control.
For 300 more rpms than stock just get a good set of springs, pushtubes and roller chain. You aren't building a 8000 rpm stock car engine.
The bottom end is ok as long as you aren't spraying or blown.
LS1Tech and some post here talk about 7k. Valvetrain will be obvious. Springs with Ti retainers are probably a requirement.
How much spring depends on the rest of your valvetrain. An aggressive aftermarket cam, more substantial rockers, solid core stainless valves, larger valves, etc will all add to the spring requirement.
If pushrods bend then pushrod. Most people who have reported 7k have changed the pushrods with their cam swap.
Some people swear by the stock rockers. Some change them. Just note that the stock pieces are very light reducing valve spring load.
And the double roller chain.
Most people say the stock bottom end is good for 7k. No personal experience here. DJWorm's shopping list would be good above 7k. Many builders sell a prepared bottom end with stock crank, stock or low-end aftermarket rods, and aftermarket pistons. Stock main caps. Around $2500-3000 is I remember correctly.
Again, if you are going to run a 24 hour endurance race or extensive DEs your requirements are different than a street engine which sees 7000 once in a while for a brief moment.
Again, if you are going to run a 24 hour endurance race or extensive DEs your requirements are different than a street engine which sees 7000 once in a while for a brief moment.
Extensive DE's is my intent. I'm likely going to go with the GM Grand Am cam which is low lift, long duration, and the GMPP Lingenfelter CNC LS6 heads. That combo likes to spin up past 7k, but I don't want to sink a bunch of $$'s into this motor - would rather save for a 427.
It'd be nice not to have to shift into 5th before going into turn 17 at Sebring.
AHH....Jesel does have an LS1/LS6 application but on further review I found that it is for dry sump systems and also drives the external oil pump. It's used on the C5R. I knew I had seen it some where.
The cover does not allow for a crankshaft snout mounted Gearotor pump as on the wet sump block. Sorry
BTW Cloyes or Rollmaster would be my choice of double roller chain/sprocket sets.
AHH....Jesel does have an LS1/LS6 application but on further review I found that it is for dry sump systems and also drives the external oil pump. It's used on the C5R. I knew I had seen it some where.
The cover does not allow for a crankshaft snout mounted Gearotor pump as on the wet sump block. Sorry
BTW Cloyes or Rollmaster would be my choice of double roller chain/sprocket sets.
Although I haven't used them with a cam-in-block, I like the sport import style ones that allow you to adjust the cam timing with five bolts. I believe Crane sells one.
Ideally it would be coupled with a 9 slot lower gear to get into the ballpark, and both would be billet.
Extensive DE's is my intent. I'm likely going to go with the GM Grand Am cam which is low lift, long duration, and the GMPP Lingenfelter CNC LS6 heads. That combo likes to spin up past 7k, but I don't want to sink a bunch of $$'s into this motor - would rather save for a 427.
It'd be nice not to have to shift into 5th before going into turn 17 at Sebring.
That Grand Am cam is a bad mutha! Along with the LS6 CNC heads and LS6 springs you won't have a problem. That is exactly what that cam was intended for, high RPM and reliable operation using the stock valve train. The key is in the low lift, long duration.
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