*mods* if this needs to be moved to regular tech, please do so, but to me i consider it "advanced"


i would like some suggestions on a custom cam design for the following LT1 setup.

i want the best mid-top end i can get........im willing to sacrifice some low end. i just want really high trap speeds. most of my driving is done on the highway, and i want to get the best pull from 50-150mph.

car is an M6 95 lt1, other than the cam, and 1.6rr etc etc, i will have fully ported heads (lloyd elliot) with 2.02 and 1.60 valves, long tube headers, and the basic boltons. i will probably stay with the 3.42 rear gears, unless advised otherwise.

flow numbers will be similar to the following +- a few :

200 - 130/120
300 - 190/150
400 - 250/180
500 - 280/190
600 - 290/200

 

no suggestions?

 

You need a solid roller. Is that what you want or do you plan to stay with a HR?

Rich Krause

 

do i NEED a solid?

i was planning on staying with a hydaulic, since i daily drive it, and heard that there is a ton of maintenance to do with a solid roller.
if this isnt true, i would definetly consider it for more power.

also, i have no concern for emissions, and i dont care about drivability.

i just care about utilizing the max top end with the given setup.

 

Some thoughts:

1) With 275/40-17 tires and a 3.42 a buck-fifty is 6700 in 4th or 5000 in 5th (give or take a few rpm). Changing to a 4.10 gives you 6000 @ 150.

2) Let's assume your power peak will be closer to 6700 than 5000, and that the car will have more than a 150 max speed (in 5th), it would seem logical to change to the 4.10. However, with the 3.42, 50 is the bottom of second, and 150 is the top of 4th, and IF you really race from 50 to 150, you'll probably be quicker with the 3.42 and the stock M6. At least my software program says so.

3) Asuming you are making some power, traction will be a problem, and gear isn't going to change the 1/4 mile trap speed a lot. Again, stay with the 3.42.

4) Using a 6700 shift, the engine never gets below 4500 or so after launch. Build for 4500-6500 power band. That's pretty easy to cam, as others, like Rich will tell you.

5) To actually spec a cam, I'd want to know a little more info like exhaust from the headers back, inlet plumbing, LT1 or LT4 intake, compression ratio.

5) To win the money, you can't run over your crank and rods. You are going to be above 6000 longer in a 50-150 pull than a 1/4 mile drag. IMO, rod and rod bolt strength would be a concern. At least look at better rod bolts.

6) Watch out for those old (gray haired) farts in a Impala SS. They might just smoke you.

 

As usual OldSStroker is on target. As implied, you have to think of the whole combo. Do you already have a motor, or are you in the planning stages? To get what you want, you should pick the cam as the next step (since you already know what heads you are going to use) and build the motor (wrt compression ratio) to match the cam. Besides what OldSStroker asked, what fuel do you plan to run?

Rich Krause

 

thanks, that why i was asking.

i have the motor, its stock. i plan on buying then installing the headers, cam, heads, and valvetrain all at once, then renting a dyno for the proper tuning with all components in place.

i get 93 octane at the pump, so the compression needs to be able to run on that.



as for what oldss said about the other info,

exhaust will be JetHot longtubes for the headers.
then i was going to run true duals, but a friend offered me a good deal on his setup hes getting rid of which is a 3" ypipe, to 3.5" intermediate pipe, 3.5" bullit racing muffler, 3.5" over the axle w/bolt together flange, dual out, for about $125.
i figure that is worth getting, since a y-pipe alone cost more than that. think that will be sufficient?

i was going to use the lt1 intake, ive heard this outflows the heads anyway. should i bother getting an lt4?



also, you didnt mention anything about why i NEED a solid roller, or if its feasible for a daily driver.

 

The exhaust sounds pretty good for your power range.

If you are really running to 150, consider lowering the front an inch or so. It will help you above 120 or so by reducing drag. Don't raise the rear to get the same rake.

After you build the engine, work on getting the correct shift point, especially the 3-4 shift. This won't be easy to do on the road, but it's important to optimize it.

BTW, I strongly urge you not to race on the road to a buck-fifty.

Rich, had to LOL at "Owner" of Buddy and Pee-Wee, the "weapons of mouse destruction". I missed that up until now. We're canine people here.

 

yeah, was gonna lower it all around, but wanted to see if i could find a 1 inch drop for the rear, and maybe a 1.5-1.75 for the front.


by looking at the dyno graph, im guessing i would be able to pick the best shift point, then install a shift light, right?


well, im sure everyone here is guilty of the occasional street race.

i just choose to do mine on an empty highway at high speeds.

i never race at stoplights, or in the city, like the average racer does. theres just too much chance for an accident.

 

First off, not to rain on anyone's parade, and not to say someone elses experience might be different; but I've had 3 friends die and another seriously injured while traveling @ speeds over 100mph. As for friends street racing from light to light....heard of a few wrecks but NONE w/ injuries. Then there was one event that got national news that happened 5 miles from my high school stomping grounds where a guy in a 5.0 was racing another mustang @ appx. 95 in a 35 and managed to rear end his own mom and kill her and her passenger.

Now, as for the solid roller, if you get poly-locks and are willing to pop off the valve covers and make slight adjustments about every oil change or so, you will be rewarded w/ power throughout the rpms that a hydraulic couldn't achieve, at least wouldn't achieve w/ any sort of streetable idle and low-end.

 

just did a bunch of reading on solid roller setups.


im not sure if it will really be worth all the money for the setup im doing.

im only looking for about 400 rwhp n/a, and im pretty sure thats attainable with a good hydraulic setup and good heads.

a decent solid setup im estimating will cost me about $1g just for the valvetrain/cam right?

 

A HR cam can certainly make 400rwhp. The only concern I have is that if I am understanding your posts correctly, you have a stock bottom end? If this is tru, there are two issues. With stock CR you need to be careful not to use a cam with to late an intake closing (typically, a long duration cam with narrow LSA). This will lead to a dynamic CR which is too low with the consequnece being degraded throttle response and gas mileage along with lower hp. Second, all other things being equal, a key to NA power is revs. And the stock bottom end will not be tolerant of very high revs.

If I were designing a heads/cam combo to use with a stock bottom end, I would try to put the peak power not higher than the 6,200-6,400 range and emphasize midrange torque.

Rich Krause

 

On spray that combo would work with a low dynamic CR nicely. I know of one board member who has been sucessfully running a mirror combo on a stock bottom end touching 10's...so it is possible as long as you don't go lean on the spray...
The stock bottom end is a lot stronger that everyone thinks...and can sucessfully handle some higher rpms if detonation is eliminated....

 

We were spinning the old cast crank/pink rod engines to ~7200 rpm every weekend. Pretty consistent too, considering these were "budget" bracket-race engines. I agree a bolt upgrade is needed but the new PM rods are supposedly stronger than the ol pinks, so I'd feel pretty confident in running n/a at ~7000 rpm as long as you aint gonna make a career out of it and have a good oiling system.

-Mindgame

 

wrt to the cam question... everyone likes to make guesses at this stuff but I don't see how you can come to such conclusions without extensive resources. A PV diagram would be tops on that list... which I'm most certain the pros (the guys who grind cams or design them in-shop) have access to.... ie, a software robust enough to simulate such a thing accurately.
All this other fluff is bench racing at its finest IMO.

-Mindgame