Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
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My friend has Vortec heads and a HSR on his L98 stock bottom end ans has the older SLP cam that is kinda small 208/216 .480/.490 or something like that. What would be a good cam to go with? I'm planning on tuning it with my Ostrich then burn a chip for it after it is set good. Stock 3.27 gears for now and a S10 converter with a rebuilt 700R4. Would this work decent? Maybe with a 112 lobe sep. ?
do you want a flat tappet hydraulic or hydraulic roller cam?
whats your converter stall speed?
whats the true compression ratio?
do you need to pass emission testing?
whats your spring bind height?
any other info you can supply?
keep in mind those vortec heads (even ported) will become restrictive even when matched to a HSR by about 6000rpm,and your transmission generally shifts before you hit 6000rpm, so theres no sence in selecting a cam that makes most of its power well above that rpm point.
most vortec heads are restricted to either a .480 lift or with better springs installed on some heads to a .520 lift, so verify your clearance issues before installing a larger cam, STOCK rods and rod bolts generally cause clearance problems unless you use a small base circle cam once both the durration exceeds about 225 deg. and the lift exceeds .520 in a stock short block
Last edited by grumpyvette; 01-09-2009 at 11:01 AM.
They have different springs and 4 angle valve job. It's a roller cam stock '90 block short block, stock pistons, etc. I think compression is around 9:1 with the Vortec heads I can't remember what we figured it out to.
Keep the power where the rest of the engine wants to run. The HSR might support big revs, but the stock bottom end isn't gonna like going to 6000rpm +. You've got a +/- 2100rpm stall and a pretty middle of the road gear, the e-bay cam probably wouldn't be the best match. I don't think I'd venture into the 230*+ duration stuff without the bottom end and drivetrain to work with lots of rpm. That SLP cam doesn't acutally sound too bad, but you could probably get away with a little more lift and duration to take advantage of the HSR, if the heads are setup to tolerate .520" or so.
I got the specs off here before I'll have to find them. What about a ZZ4 take-out cam? Worth the time/effort? I didn't realize the stock bottom end was that delicate with revs.
YOU DO REALIZE thats an LT1/LT4 cam thats linked too, don,t you?
and while its possiable to use it in a L98 it would be far better to have the GEN1 version in the engine.
LT4 hotcam if your heads can handle the lift. Best bang for the buck cam available as you can find it used fairly cheap. Peak by 5800 or so, shift by 6K. That car will put down good numbers and be driveable. Works well with HSR
YOU DO REALIZE thats an LT1/LT4 cam thats linked too, don,t you?
and while its possiable to use it in a L98 it would be far better to have the GEN1 version in the engine.
Yea, I just ballparked a reasonable lift/duration for the combo, as you say the GEN I cam specs almost identical and presents less issue, fair call.
What do you guys feel about the stock bottom-end shifting at 6k on a regular basis. It was my understanding much over 5500rpm or so on a stock SBC bottom is asking for a rod bolt to punch out for early retirement.
stock rods will hold up to 6000 rpm,in most cases simply because your at 6000 rpm for only a few seconds at a time, but if your serious youll build a better bottom end rotating assembly with forged 4340 rods with 7/16" arp bolts.
because at 6000 rpm a standard piston weights or more correctly the connecting rod sees a 10,000-12,000 lb PLUS load as it changes dirrection from TDC to bdc on the exhaust stroke where its not compressing much to slow it down as it plays crack the whip on the small end of the rod.
but if your going to replace rods, bearings, pistons ETC, you may as well build a 383 or 396 stroker with forged components in the lower end to maximize the strength and hp potential.
the problem with this hobby is theres ALWAYS just a bit more you can do to boost hp or add relieability,and it always seems to cost more money than most of us have to spend.
Last edited by grumpyvette; 01-10-2009 at 08:37 AM.
LT4 hotcam if your heads can handle the lift. Best bang for the buck cam available as you can find it used fairly cheap. Peak by 5800 or so, shift by 6K. That car will put down good numbers and be driveable. Works well with HSR
I was just looking at that yesterday, lol. What is needed to use it in a L98? Just shorten the pin?
I would still argue that stock rod-bolts may give you trouble with lots of 6000rpm+ running. Here is the thread I had in mind when I mentioned keep the bottom end together for regular duty over 5500rpm...
