Randy WS6

iTrader: (69)

My crank and rods will be here tomorrow and I need to know what is the best cam for a 4.100 stroke & 4.030 bore Comp pro mag. adjustable roller rockers 1.75 and should i go solid or hydraulic lifters I have a M6 and 4:30 gears and see track time every now and then but like to stay under .650 lift cam because i have new Patriot Gold spring & titanium retainers. Right now i have a T-REX 242/248-609/614-109 ,The duration looks small on this cam becouse it want keep the valve open long enough for the stroke and bore ,Does this sound right? I would like to get some idea's on the cam before i order the pistons for the valve releaf ,My heads are shaved 0.030 and head gaskits MLS 0.042 i think

Ls1Rx-7

iTrader: (4)

i hope you mean 402 ls2, cause the 6.2 liter block hasnt been released yett and thats the block that u get 418 cubic inches from not the ls2. but if i were to suggest a cam for your (402) i'd say somewhere like a 25x/25x and low lifts (just over 600) since u wont be revving the **** out of it. and i see that your running nitrous on ur 346, you may want to run a splitt duration cam and retard it some.

The Guy in MY 99TA

no he is right with a 4.100 stroke and a 4.030 bore you get 418 or so inches


now I have to ask why did you choose to go with a 4.100 stroke? I personally don't like the idea of it(i'm going 4.00x4.00)... but I'm just asking why you did it or what benefits there are of going with the large stroke.

Josh S.

Randy WS6

iTrader: (69)

There are a few people on here are running the 05 aluminum 6.0 block boring them 0.030 over with no problem at all.you can do a search on here to see and for the stroke is for the cubic inch. 418cid. there are people on here using a 4.125 cranks and 0.030 to get a 422cid. Ive been told that stroke is tork and bore is horse power. A 4.100 crank cost around 950.00 and a 4.125 is around 1700.00 its just to much money for 0.025" and 4 cubic inches. The motor on here that has been bored has been sonic tested and had plenty of meat and the factory suggest not to bore over 0.020" that is 0.010" off each side of the block so if you go 0.030.over your only taking a extra 0.005" off each side and the blocks are simized like the LS7 block with are much stronger than the old LS1 & LS6 blocks I will have it sonic tested and if wont go 0.030 ill go 0.020 over and build a 414cid. Im running a all forged 348cid. with a 250 hp n.o.s. and shifting at 7600 rpms and been doing it for over two years now with no problems at all and ive done a lot of racing in those two years now and its steal running perfecty and after i build 418cid . i will freshen it up my 348cid. and put it up

The Guy in MY 99TA

I have just heard from some people that its just not something to do by going with a larger stroke than the bore. What would the torque curve on this setup look like vs. a 4.00 stroke?

Randy WS6

iTrader: (69)

tobe onist i dont know but Mreracer might ,he's the one that is building these 6.0 aluminum 418's & 422's and racing them. You can pm him ,He's been very helpful to me on my 418 build.

SSblack98

iTrader: (8)

Actually 4.020 bore/4.1" stroke should give you 416.3 CI. I don't understand why more people don't run the 4.1" crank. It is like free cubic inches with no apparent loss of reliability! "Tosto Racing" on here is running what I believe to be a 421 CI with a 4.030 bore/4.125 stroke and shifting it at 8000! He is also the only N/A 6-spd car in the 9's as far as I know so the longer stroke can't be all that bad! I think he is running the iron block but that shouldn't matter for bore/stroke comparison. If the L92 block isn't available sometime next year I will likely build a 416 CI solid roller with an LS2 block 0.020 over w/4.1" stroke and shift about 7500. I am not brave enough to try .030 over on LS2 block but many say it is OK. I'm also not brave enough to shift an undersquare engine at 8k but apparently that can work also! I think you would want a solid roller cam in the high 250's-low 260s duration w/lift in the 650 range. Hydraulic would be slightly lower duration and lift in the low 600s. I am no cam expert however. Anyway, just my 2 cents...

Randy WS6

iTrader: (69)

Thanks

DavidNJ

Reading this reminded me of this exchange in volunteers:

Chung Mee: Opium is my business. The bridge mean more traffic. More traffic mean more money. More money mean more power.
Lawrence Bourne III: Yeah, well, before I commit any of that to memory, would there be anything in this for me?
Chung Mee: Speed is important in business. Time is money.
Lawrence Bourne III: You said opium was money.
Chung Mee: Money is Money.
Lawrence Bourne III: Well then, what is time again?

Increased bore unshrouds the valves for more flow and increases displacement. Torque is increased everywhere from both the displacement increase and the flow efficency increase. Plus there isn't an increase in piston speed.

Increased stroke increases torque, but not flow efficency. Once flow becomes the restrictions there isn't more torque.

Since peak power occurs at higher engine speeds, increased stroke may show a smaller increase in peak power relative to peak torque. It may also lower the engine speed peak power is achieved at. And the increased piston speed may limit maximum safe engine operating sped.

Power is a direct function of torque, you can't increase one without increasing the other. What you can do differently is affect the shape of the power curve.

Your current cam is 242/248 109? And you want more?

Obviously, emissions isn't an issue. Is your idle ok?

You could increase your flow with more lift, Comp Cams LSK lobes. This would be like adding bigger heads, if the heads are the limitation. If there are other flow restrictions (tb, intake), you may want to tighten the lsa or add advance to move the power curve down. If you are ok with your idle now, you could increase duration.

Thunder's TRAK is an LSK cam, so you may want to talk to them. Maybe a T-RexK (I up that name) with 243/248 .653/.630 109. The LSK lobes are listed up to 263, in case you wanted to go bigger. You would need new springs in either case.

Nate_Taufer

iTrader: (1)

A .030" over ls2 block still has more meat on the sleeve than a factory ls1/ls6 block. I don't know why you'd be so scared? It has about .105" of liner material with about .200" of aluminum backing it up. Plenty strong enough to take it .030" over resulting in about a .090" liner.

Nate

Randy WS6

iTrader: (69)

243/248-627/633-109 this is what my T-REX will be with my Comp Pro Mag.1.75 would this work o.k. with my set up

Randy WS6

iTrader: (69)

My LS2 block is going 0.030 over ,If it splits the cylinder ill buy a new block There is no emission laws here in Kentucky and my motor idols fine

red90cobra

iTrader: (36)

yes it'll be okay

DavidNJ

Just noticed your other post that indicated this is really a NOx race car.

Then yes, why are we: 1) talking about street cams, 2) using hydraulic lifters.

Big Block mechanical roller drag race cams in the Comp Cams catalog for 11-12:1 compression and 4:10+ gears all have numbers 260-275 intake and 275-285 exhaust with over .7" lift. Even the oval track cams are 250-260 intake, 260-275 exhaust with .68+ lift.

For reference. My 358cid SBC with cast iron bow tie heads, 12:1 (110 octane) compression, a 2-bbl carb, and little .842" flat tappet lifters (the limiting factor), uses a 248 intake with 1.8 rockers and a 256 exhaust with 1.6 rockers. Others use 256/260 range with 1.5/1.6 rockers.

I don't think you can get there with hydraulic lifters or those springs (or probably any 1.75" high, 1.29" spring. You would need something like a 2" tall 1.58" spring, which is what the new World heads seem to be designed for.