DAPSUPRSLO

iTrader: (14)

First I orignally ordered this cam with a 110icl but changed it to a 108icl to help with my exhaust valve clearence. I am worried about p to v clearence so if any of you have had experience with similarly sized cams on stock heads let me know.

I just ordered my cam after crunching some numbers comparing other popular cams (i.e. TSP 231/237 cam and the G5X-2 cam).

I campared the four parameters of EO (Exhaust Opening), EC (Exhaust Closing), IO (Intake Opening), IC (Intake Closing). All numbers were compared at .050 tappet lift, which all of the duration numbers of the cam are listed.

Campared to the 231/237 my cam does the following:
My EO occurs 4.5 degrees later (excellent torque)
My EC occurs 3.5 degrees later (excellent scavenging, p to v may be a concern)
My IO occurs 0.5 degrees later (combined with the EC this should create some nice scavenging)
My IC occurs 0.5 degrees earlier (closed the Intake Valve 45 degress ABDC {after bottom dead center}

Compared to the G5-X2
My EO occurs 7 degrees later (deffinately more torque)
My EC occurs 3 degrees later (see 231/237 comparison)
My IO occurs 2 degrees later (see 231/237 comparison)
My IC occurs at the same point

It must be noted that the G5-X2 numbers were based on an ICL of 109 and not 108 like it is ground un so adjust all numbers accordingly.

I will surely have my hands full with ls1 edit on this cam. However, I think it will make some big power but only dynos and mph will tell. Also, the intake valve will be ground on the very aggressive thunder 230 lobe but will only have 570ish lift. The exhaust will be a comp xe lobe with around 570 ish lift. I am siked. The only thing I am worried about is p to v contact but with stock heads I think I will be alright.


__________________
01 Pewter Hurst M6 (I'm not 70 yet, ha ha) SS #1215
SLP Options: Chrome 10 Spoke Wheels, Dual Dual, SS Grill
My Options: Wheels: 17x9.5 17x11 zr1 replicas with nitto 555 fronts and 555 extreme drags
Mods: Every bolton plus a thumpn' 224/224 565/565 106icl 110lsa comp xe cam
Wheels: ZR1s with nittos (315 in the back)
Dyno: uncorrected rwhp/rwtq, 415/417, corrected 405/406
Moser 12bolt, 33 spline, eaton posi, 4.11s
230/236 108lsa 108icl Cam on the Way

JoSeY

108...plannin on idling @ 1300 huh?

DAPSUPRSLO

iTrader: (14)

Why not?

CHRISPY

Looking forward to hearing how the cam works for you!

How much vac do you think you'll pull?

Damian

iTrader: (89)

Sounds like a sweet stick, I was going to run something similar a while back...

BTW, lower the ICL gives you less PV clearance. The 110LSA/110ICL would have given you more clearance than the 108/108 just FYI..

Josh

DAPSUPRSLO

iTrader: (14)

Yeah, I know. The lower lsa closes the exhaust valve later, two degrees when comparing 108lsa vs. a 110lsa given the same icl.

DAPSUPRSLO

iTrader: (14)

Anybody with any p to v knowledge of a similar cam.

bodhi

I see flycutting in your near future...

DAPSUPRSLO

iTrader: (14)

Because of a guess or because you have knowledge of a similar sized cam on stock heads?

Bad Habit Bird

iTrader: (12)

Damn your car makes some serious tq! Definatly keep us posted on how this new cam works out for you.

MysticZ28

The model I have disagrees with your calculation on the EC ... I have that at 7.5 degrees later the 231/237, at 10* ATDC. It's my understanding that is rather beyond what is considered safe for PV clearance for EVC ... 4-5*ATDC ...

I've modeled a lot of the more popular cams and nobody is more than 4* ATDC on the EVC ...

My take is not only are you going to be fly cutting, you're going to be fly cutting deep ...

DAPSUPRSLO

iTrader: (14)

Thanks for the tech input. However, I don't see how you are getting your numbers. My lobe is 1 degree smaller. Divide that by two for the closing point and you get .5. My cam's icl is 2 degrees advanced compared to the tsp 231/237. This causes the exhaust valve to close later on the tsp cam by 2 + the .5 for the difference in the size of the exhaust lobes. However, my cam pulls the ECL back 4 degrees because of the 108lsa vs the 112lsa. This equates to 1.5 degrees later on my cam. My original number of 3.5 degrees was based on a 110icl but then I changed my mind to a 108icl which subtracts 2 degrees from the difference for 1.5 degrees later EC of my cam. Confusing stuff hugh.

Damian

iTrader: (89)

DASUPRSLO, just curious why you're interested in doing something like this. Lowering the ICL will work for moving your powerband down, but your cam will also run out of breathe faster IMO. If low end TQ is what you want, you can run something with a somewhat higher ICL, lower duration, and make great TQ #'s while still making a good peak #..

FWIW, my cam is on a 114 LSA + 0 = 114 ICL. I make 409 ft lbs of TQ @ 4400 rpm's and made 455 rwhp hitting the limiter @ 6800. My 114 makes great power and it carries, instead of dropping off. If this same exact cam was on a 108, my powerband wouldn't carry nearly as far. I have experiemented with lower LSA/ICL cams, and needless to say I am running a 114 cam now.

josh

DAPSUPRSLO

iTrader: (14)

More overlap means more power, that is why. I made 406rwtq on stock heads with a small 224 cam and 110 lsa. The reason most of these cams fall of quickly is because of the associated advance ground in. Four degrees advance on a 114 equals a 110icl while four degrees advance on a 110lsa equals a 106icl. Look at all the race cams offered by sponsors for sbc's.

I, like the article in GMHTP, believe that there is only one given lsa for the greatest amount of power in a given power band. With a longer stroke a motor will always like a tighter lsa because of the piston speed is increased causing a greater suction affect taking advantage of the overlap period. As you know the ls1 has a greater stroke then the sbc and cams with 106 and 108lsa have been showed to make the greatest power on these setups.

This is also a big reason we don't see the superstrokers making big power compared to the heavy hitting 346 packages. That, and the restrictive ls6 intake. These motors need big cams to take advantage of increase piston speeds of long strokes.

J-Rod

DAP, you are going in the right direction. What you are doing right is looking at your valve events and not getting hung up on LSA. Folks need to stop getting hung up on an arbitrary number for LSA (112 114, etc...), pick goood valve event, and the LSA will be a byproduct, and not the goal.

BTW, a 108 LSA with good VE will idle better, not hunt buck or surge, than a 112 with bad VE's. Just a little food for thought.

On the pistons, depending on lift, with your VE's you may have to flycut. I haven't done all the math, but it is possible. You can have a cam with 1" lift as long as the timing and durration doesn't put the valve at max opening while the piston is at TDC... Last time I checked, in most cases the intake valve is just BEGINNING to open (nowhere near max lift) slightly before the piston reaches TDC and isn't completely open until the piston is near BDC. It's simple folks, max lift means nothing when talking about PTV clearance. If PtV was an issue at max valve lift, all we would do is check for clearance at that point and call it good. This would lead to many engine failures as it would show you have a MILE of room. PtV becomes an issue during the overlap cycle, where the exhaust valve is closing and the intake valve is just opening. Your tighest clearance is going to be roughly 10* BTDC for the exhaust valve and 10* ATDC for the intake valve.

Duration, intake centerline, ramp rates, etc. play a MUCH more important role than max valve lift. It is ALL in the timing events. If you have too much duration then your exhaust valves will be too far open for too long and the piston will smash into them on their way up on the exhaust stroke. If there is too much advance ground into the cam and you have too high of a ramp rate then the intake valves will be too far open too soon and again mr. piston and mr. valve will kiss. These are just two examples of many that could cause problems, and they didn't even take into account many other factors. You only have to worry about PTV when the piston is nearing it's TDC, at TDC, and slightly after TDC, not when the valve is at full lift. And once again, "Duration, intake centerline, ramp rates, etc. play a MUCH more important role than max valve lift. It is ALL in the timing events." Picking a cam for a motor isn't as simple as putting a round peg in a round hole and when it fits, patting yourself on the back and calling it a job well done.

If you want to do what you are talking about, give Ed @ flowtech a call. But, I will tell you that when he looks at your cam specs the first thing he will suggest is that you swap your lobes to a 236/230 maybe a 236/232. Anyhow, you are on the right track with keeping the LSA and ICL in line and not putting additional advance in the cam.... Let us know how it comes out...

Damian

iTrader: (89)

406 rwtq is impressive, but only about 4-6 over a normal 224 112. Most 224's make 395-405 rwtq depending on the combo.

Just curious, where are you getting your data to make these conclusions? I understand your formulas, been there many times. Just wondering if you have any solid info on this? Examples?

Superstrokers make big TQ, and area under the curve. Much more so than a 346, so I believe they're doing their job even with an LS6 intake. For example, take a 382 motor making 450/410, and overlay a graph of a 346 making 450/410. More times than not, the 382 is going to have much more under the curve, and be the faster car assuming conditions are similar in weight, driver, etc...

I disagree on these motors needing big cams to make power. My cam for example is half the size of most popular cams being ran today and I make great power. I've also personally seen some of the biggest cams available for the LS1 tried and tested with somewhat disappointing results. Big cams make a great peak #, but that does not make the car faster.

Cartek for example, made equal power w/ a 224/228 112 cam to LG's 232/240 cam, and their cars run 127+ mph in the 1/4. Cartek doesn't run big cams, and their cars make great power. This isn't meant to flame or talk down upon LG, just stating that it's not always a big honkin stick that's going to produce the best results. The COMBINATION is most important part of building a motor...

Josh

DAPSUPRSLO

iTrader: (14)

The reason you make great power has alot to do with your heads. The ls1 comes with excellent flowing heads that provide excellent port velocity. Also, the intake manifold is a big limiting factor of the power produced by h/c combos. I gaurantee that if you replace your current cam with one with tighter lsa and less duration then you will make more power and more area under the curve to a certain extent. Remember, making a power band peakier is o.k. if that is the band you are in when you race. Talk to Al Corda and I bet he isn't running a cam on a 114lsa.

The sbc has a 3.48" stroke and the ls1 has a 3.625something stroke. As for the articles I will have to get the mags from my friend. The GMHTP article however is contained in the mag with the two SSs, A Black 422 which sprays and a Red 382 all bore which sprays. The article is called something like "A Cam for Optimal LS1 Events".

We can sit hear and theorize all night but the bottom line is that I won't know until I try it. If you can find it you might want to dig up the thread where they compared the G5X2 on three different lsa's, a 114, 112, and 110. The 110 beat the others everywhere except for the extreme top 100-200 rpms, not just peak.

mikemodano9c

what definition do you have for a "aggresive thunder 230 lobe" and a "comp xe lobe"

you can say your cam will have a very aggresive "thunder" lobe, but what exactly is that? is there a certain ramp rate or calculation you are using to conform to this? so you have X lift and and X duration...what is you specification for how steep the lobe is to be considered that? all i see is these terms thrown around and i just want someones answer to these questions...

just being a fast ramp rate isnt good enough for me...i want to learn here

v8 ute

My fly cuts are deep.

Mine idles just under 1100 rpm.

Sometimes it seems there low vaccume and the brakes arn't going to pull you up but that is very rare.



Just put it in tune it and see what you think

JoSeY

How do u like the 234/238...I'm considering swapping my X1 for one but on a 114 LS or 112...depending on Jaysons majical dyno touch....